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3D MODEL OF A PNEUMATIC DISTRIBUTOR
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
R. de Giorgi and E. Bideaux and N. Boisson,
2006, August 2006
view abstract
The performance and life time of pneumatic components, such as valves, are strongly a ected by the inside
air
ow circulation in stationary and dynamic conditions. Component global behavior is also a ected by local
phenomena generated by di erent positioning of the component moving parts.
For example in a pneumatic distributor, some spool or poppet positions might result in recirculations that
generate pulsed jets. The following vibration will a ect not only on the component performance at that position
but also on its life time. Experimental analysis can detect an odd behavior, but usually cannot show clearly its
real causes. Furthermore experimental analysis can be performed only on an existing component and cannot be
used as aid tool in the early design phase.
The use of Computational Fluid Dynamic (CFD) appear to be an interesting approach in this context. In this
paper is presented an air
ow 3-Dimensional model of a pneumatic distributor for di erent spool positions. The
aims of this paper are to show how a simulation can detect local phenomena generally difficult to identify and
study using experimental analysis. In order to appreciate the simulation quality, the comparison of the simulation
results with experimental data are based here on the pneumatic distributor mass
ow rate characteristic.
A 2ND – ORDER ROBUST ADAPTIVE DIFFERENTIATOR – CONTROLLER DESIGN FOR AN ELECTROPNEUMATIC SYSTEM
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
L. Sidhom and M. Smaoui and M. Di Loreto,
2008,
pp. 186-197,
Juli 2008
view abstract
We propose in this paper to develop and to use a 2nd-order robust adaptive differentiator. From the only measure of the
position, we are be able to accurately estimate the velocity and the acceleration of a servo drive system. Initially developed by Levant, this differentiator is based on high-order sliding mode. The adaptive feature has been added to the 2nd classic robust differentiator in order to overcome the specific drawback of parameters tuning. The aim is to show the effectiveness of this adaptive differentiator design on the control of an electropneumatic system. Furthermore, the choice of the differentiator design is an important task for the control system. A comparative study is made between the robust adaptive differentiator based on sliding mode and a classic digital differentiation algorithm, in order to show the effectiveness and the influence of the structure differentiation algorithm on the control of the electropneumatic system.
A 4 d.o.f. Upper-Limb Orthosis driven by Pneumatic Muscles
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
F. Durante and T. Raparelli and P. B. Zobel,
2004,
pp. 123-130,
Juni 2004
view abstract
A powered orthosis can be used to help people with disabilities to improve their motion capability. The primary goal is to grow the degree of independence of the user in a certain number of daily living tasks. In this paper the design and the manufacture of a 4 d.o.f. (degrees of freedom) powered upper-limb orthosis is presented. The orthosis is an exoskeleton worn on one arm by the user. The design process of the orthosis is described: mechanical design and manufacturing are described, the estimation of the range of movement related to daily-living activities is presented. Considerations on the control system, not yet implemented, to manage the motion of the orthosis are also included. Some preliminary tests to verify the functionality of the design show encouraging results.
A 7-Axis Hybrid Hydraulic-Electric Manipulator for an Underwater Robotic Vehicle
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
M. W. S. Lau and G. Seet and A. Thondiyath and D. Liew and E. Low,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 281-288,
November 2003
view abstract
Current manipulators on URV are tele-operated and hydraulically actuated. They have a
simple remote control capability (master-and-slave configuration) but they lack dexterity for
fine work. They hard to control and have poorer positioning accuracy compared with electric
motors, but has very good load-to-power advantage. A 7-axis hybrid hydraulic-electric power
manipulator that combines the power of hydraulic and the dexterity of the electric motor
system has been designed. Such systems are not well exploited in current URV systems. The
first stage uses hydraulic power for posing the second stage. It requires less positional
accuracy, but higher torque. The second stage has a shorter reach, needs higher positional
accuracy and requires lower torque. It can use smaller electric motors. A mock up of the
manipulator has been deployed in a swimming pool test to study the vehicle stability. The
design and simulation would be presented. Simulation results and experiments of the electric
stage have demonstrated its viability.
About Calibration of Light Extinction Automatic Particle Counters
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
C. Peuchot and N. Petillon,
2007,
volume 2,
pp. 445-453,
Mai 2007
view abstract
Light Extension Automatic Particle Counters are the favourite instruments used in independent and industrial laboratories to measure the particulate contamination level of hydraulic fluids, fuels and in some cases, lubricants. As well, they are the only reliable instruments to count particles upstream and downstream filters to measure their instantaneous efficiency at various sizes. These two families of applications are detailed
in several international standards.
As all measuring instruments, they have to be regularly calibrated. Because oil has chemical and optical properties different from that of water, the size calibration material
cannot be made of latex spheres as recommended in USP 28. ISO 11171 defines SRM 2806 certified by NIST as the APC calibration suspension. It is made of classified silica sand in a standard mineral oil.
The authors describe the way the new batches of SRM 2806b shall be prepared and certified. They make some proposals to make ISO 11171 and ISO 11943 easier to understand and apply for not expert end users. Some results of international round robin
tests performed these last years within few ISO expert groups are presented and interpreted from the point of view of APCs calibration.
About the Prediction of Pressure Variation in the Inter-Teeth Volumes of External Gear Pumps
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
B. Zardin and F. Paltrinieri and M. Borghi and M. Milani,
2004,
pp. 607-621,
Juni 2004
view abstract
The paper deals with the analysis of the inter-teeth pressure transients during gears meshing cycle of
external gear pumps. A lumped parameter model, tailored for the prediction of pressures in the meshing
zone, is firstly presented. The numerical model, based on the integration of the continuity equation, is
applied to the inter-teeth volumes, communicating with the neighbouring ambient through geometry
dependent orifices. A comparison between numerical results, obtained considering both constant and
variable discharge coefficients, is illustrated. Successively, the dependency of pressure transients on gear
pump operating conditions, mainly in terms of delivery pressure and rotational speed, is investigated. The
effect of some geometric parameters is also discussed, mainly considering different gears widths and
interaxial distances, and high-pressure recess positioning. Finally, in order to highlight the influence of the
cavitation modelling on low pressure transition, the results coming from the application of two simplified
approaches are shown and compared.
A CASCADE STRATEGY USING NONLINEAR CONTROL TECHNIQUES APPLIED TO A HYDRAULIC ACTUATOR
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
M. A. B. Cunha and R. Guenther and E. R. De Pieri and V. J. De Negri,
2000,
pp. 57-70,
September 2000
view abstract
This paper presents an analysis of the controllers using a cascade strategy applied to hydraulic actuators
proposed by this work’s authors. The cascade control strategy consists in dividing the whole model of a
hydraulic actuator into two subsystems: a mechanical subsystem and a hydraulic one. From this interpretation
control laws are proposed to each subsystem based on different control techniques. Then, the stability of the
whole system is analysed for the interconnected systems using the Lyapunov approach. Experimental results
illustrate the main features of the proposed controllers.
A Cavitation Avoidance Strategy in Hydraulic Switching Control Based on a Nonlinear Oscillator
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
R. Scheidl and H. Kogler and B. Manhartsgruber,
2007,
volume 1,
pp. 197-210,
Mai 2007
view abstract
In hydraulic switching control a cavitation critical phase is the switching from the pressure to tank line. A high tank line pressure can generate a fast onset of the flow from the tank line into the system and can avoid cavitation in this way. But for energetic reasons the tank pressure should be kept low. In this paper a method to boost the tank pressure considerably by applying a nonlinear oscillator is presented. Its performance is studied in combination with a `Hydraulic Buck Converter`. The mechanisms of generating cavitation are explained and rules for a proper dimensioning are derived by simplified mathematical models. Due to the nonlinearity a complex system behaviour may occur, like for instance a non periodic response of the oscillator.
Acceleration Characteristics of Servo-Controlled Pneumatic Cylinder
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
J. Pu and C. B. Wong and P. R. Moore,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 119-130,
November 1996
view abstract
Knowledge concerning the acceleration characteristics of pneumatic drives is useful in the design, control, and tuning of servo-pneumatic systems. In this paper the force/speed characteristics of an asymmetric actuator are outlined and verified. The paper then considers the rate at which a pressure differential can be established. This then leads to the concept of meter-in and meter-out control zones. The results reported in this paper should promote interests in pneumatic servos for certain profile following applications.
Accounting for Elastic Energy Storage in McKibben Artificial Muscle Actuators
Glenn K. Klute and Blake Hannaford,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 386-388,
Juni 2000
view abstract
The McKibben artificial muscle is a pneumatic actuator whose properties include a very high force to weight ratio. This characteristic makes it very attractive for a wide range of applications such as mobile robots and prosthetic appliances for the disabled. In this paper, we present a model that includes a nonlinear, Mooney–Rivlin mathematical description of the actuator's internal bladder. Experimental results show that the model provides improvement in the ability to predict the actuator's output force. However, a discrepancy between model and experiment, albeit smaller than previous models, still exists. A number of factors are identified that may be responsible for this discrepancy.
ACCURATE TRAJECTORY TRACKING CONTROL OF WATER HYDRAULIC CYLINDER WITH NON-IDEAL ON/OFF VALVES
M. Linjama and K. T. Koskinen and M. Vilenius,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 7-16,
April 2003
view abstract
The aim of the work is to develop an on/off valve based trajectory tracking control solution without fast and/or continuous switching of valves. The pulse code modulation method is used to realise stepwise control of inflow and outflow of the actuator. Both inflow and outflow paths have five parallel-connected two-way solenoid valves, each having
different flow capacity according to binary series, and a four-way on/off valve is used for changing direction of movement.
Cost function based open-loop and closed-loop control solutions are developed and it is demonstrated how the
cost function weights can be used to find a reasonable trade-off between tracking performance and pressure surges.
Closed-loop results show accurate and reasonably smooth position tracking and simultaneous pressure level control.
Achieved control performance is close to that of water hydraulic servo systems.
A Closed-Form Full-State Feedback Controller for Stabilization of 3D Magnetohydrodynamic Channel Flow
Rafael Vazquez and Eugenio Schuster and Miroslav Krstic,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
Juli 2009
view abstract
We present a boundary feedback law that stabilizes the velocity, pressure, and electromagnetic fields in a magnetohydrodynamic (MHD) channel flow. The MHD channel flow, also known as Hartmann flow, is a benchmark for applications such as cooling, hypersonic flight, and propulsion. It involves an electrically conducting fluid moving between parallel plates in the presence of an externally imposed transverse magnetic field. The system is described by the inductionless MHD equations, a combination of the Navier–Stokes equations and a Poisson equation for the electric potential under the MHD approximation in a low magnetic Reynolds number regime. This model is unstable for large Reynolds numbers and is stabilized by actuation of velocity and the electric potential at only one of the walls. The backstepping method for stabilization of parabolic partial differential equations (PDEs) is applied to the velocity field system written in appropriate coordinates. Control gains are computed by solving a set of linear hyperbolic PDEs. Stabilization of nondiscretized 3D MHD channel flow has so far been an open problem.
A Combined Scheme for Identification and Robust Torque Control of Hydraulic Actuators
Mehrzad Namvar and Farhad Aghili,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 595-606,
Dezember 2003
view abstract
This paper presents a combined scheme of identification and robust torque control for rotary hydraulic actuators. The composite controller consists of a dynamic feedback linearizing inner loop cascaded with an optimal l1-H[infinity] feedback outer loop. The proposed controller allows the actuator to generate desired torque irrespective of the actuator motion. In fact, the controller reduces significantly the impedance of the actuator as seen by its external load, making the system an ideal source of torque suitable for many robotics and automation applications. The stability analysis of internal unobservable dynamics is presented. An identification method to extract the parameters of nonlinear model of actuator dynamics and to estimate a bound for modeling uncertainty, used for synthesis of the outer optimal controller, is also presented. The theoretical results of the paper are illustrated experimentally on pitch actuator of the Schilling industrial robot.
A Compact Hydraulic Switching Converter for Robotic Applications
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Kogler, Helmut and Scheidl, Rudolf and Ehrentraut, Michael and Guglielmino, Emanuele and Semini, Claudio and Caldwell, Darwin G.,
2010,
pp. 55-68,
September 2010
view abstract
This paper is concerned with the application of switching technology to hydraulic actuation. Classical proportional flow control employing servo/proportional valves is dissipative and inefficient. By analogy it can be seen as the equivalent of resistive (rheostatic) motor control.
In mobile outdoor robotic applications where high power density, ruggedness and reliability are key requirements, the low efficiency of proportional control can be a limitation and it is necessary to go beyond the paradigm of proportional flow/pressure control.
One response to this challenge is to revisit traditional on-off hydraulic technology and develop systems and devices that behave in analogous manner to their power electronic counterparts. A prototype hydraulic switching converter, inspired by the electric DC-DC Buck converter, is presented. Its design, sizing and performance relative to a classical proportional valve-controlled system are assessed in the different operation modes. Pros and cons of the current design are identified.
A Comparison of a PID Controller to a Neural Net Controller in a Hydraulic System with Nonlinear Friction
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
W. Qian and R. Burton and G. Schoenau and P. Ukrainetz,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 91-98,
November 1998
view abstract
Neural networks have been applied to a wide spectrum of applications in the last decade, including the fluid power area. The popularity of neural networks can be attributed, in part, to their ability to deal with nonlinear systems. Their use as a controller, however, poses many interesting
problems, especially when trying to apply them to practical systems. In hydraulics, PID controllers have been used with some degree of success; however, when it comes to highly nonlinear systems, this established method encounters some difficulties.
This paper considers the applied problem of a hydraulic servovalve controlling a actuator with nonlinear friction characteristics. A neural net controller is pre-trained to the performance of a special PID controller which has been tuned to a specific waveform. The plant is a model of a
hydraulic servovalve and a linear actuator with slip-stick friction characteristics. The neural net controller replaces the PID controller and shows superior performance for waveforms that it was not trained for. The addition of a "kicker" signal reduced the distortion of velocity (a consequence of nonlinear friction) when the velocity was near zero. It is concluded that in certain applications, a
neural net controller does show potential for use in nonlinear systems, but many other issues such as stability, reliability, and adaptability must be addressed in the future.
A Computational Tool for Failure Modes and Effects Analysis of Hydraulic Systems
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
D. R. Bull and C. R. Burrows and K. A. Edge et al.,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 113-118,
November 1996
view abstract
Failure Modes and Effects Analysis is widely used in engineering for the assessment of reliability. With the current practice, the length of time involved in the analysis is prohibitive and therefore its full potential cannot be used in the design process. This paper proposes a computational tool, GNOME, which, when fully implemented, will provide a faster method. This paper discuss its application to an FMEA of a simple hydrostatic transmission.
A Computer Aided Conceptual Design Method for Hydraulic Components
Power Transmission and Motion Control (PTMC 2005)
B. Steiner and R. Scheidl,
John Wiley & Sons,
ed. D.N. Johnston and C. R. Burrows and K. A. Edge,
2005,
pp. 209-221,
view abstract
In this paper a method for supporting conceptual design work of hydraulic components is presented. It links together the graphical domain of sketches/drawings with the symbol domain for reflecting the physical effects and the domain of mathematical models for their quantification. The graphical domain is realised with a standard CAD program. The designer specifies his/her concepts by drawings. The functional roles of drawing entities are declared by predefined symbols associated to these entities. In this way, the designer declares his/her physical understanding and generates automatically a mathematical description. The mathematical model for each effect is stored in a database in a notation used by the symbolic manipulation program Maple. The geometrical and material design parameters of these individual effects can be linked to parameters given by some design entities. The models of each effect are combined to a set of equations describing the whole system. Currently, the database symbols and the application are developed for hydraulic components. To exemplify the method and the capacity of the software the conceptual design of a fast hydraulic 2/2-way-switching valve with a positive feedback metering edge is modelled.
A Conservative High-Resolution Scheme for the Study of Gases and Liquids Homentropic Flows
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
M. Borghi and C. Bussi and M. Milani and F. Paltrinieri,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 187-199,
November 2003
view abstract
In this paper a high-resolution explicit integration scheme is introduced and adopted to study
the one-dimensional homentropic flow of a generic fluid, applicable to gaseous and liquid
phase. The generally valid governing equations for one-dimensional homentropic flows are
firstly introduced and, without forcing any assumption in relation to the nature of the fluid, an
investigation of mathematical properties of the system of equations is given in order to derive
the characteristic matrix and the system eigenvalue. Then, the Maxwell differential
formulation of the fluid constitutive equations is introduced, with the purpose of providing a
general state equation which retains its validity for both gases and liquids, and with the aim of
expressing and explicitly calculating pressure, pressure derivative with respect to density and
sound speed as functions of fluid bulk modulus. Starting from the differential formulation of
the state equation, a high-resolution explicit integration scheme, based on conservative
formulation of the governing equations for fluid flows, is then introduced and discussed.
Finally, the well-known shock tube test is employed to study both liquid and gaseous flows,
and the forthcoming numerical vs. analytical results comparison is used to assess the accuracy
and the stability of the integration scheme.
A CONTRIBUTION TO THE DESIGN OF HYDRAULIC LUBE PUMPS
S. Mancò and N. Nervegna and M. Rundo,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 21-31,
April 2002
view abstract
With special reference to gerotor lube pumps the paper details how a simulation environment can be instrumental in
design development. The relevance of testing is stressed as an essential counterpart to simulation. Original modelling
techniques are also proposed that provide a unified approach to volumetric pumps studies.
Acoustic Comfort in Heavy Duty Machines Operator's Cab
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
B. Stolarski,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 365-380,
view abstract
No abstract available
Active Health Monitoring of Hydraulic Hoses
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
Z. Holland and A. Deckard and G. Krutz,
2010,
volume 2,
pp. 657-664,
Juni 2010
view abstract
Hydraulic hoses, with their many layers and long runs, are often difficult to test for potential breaks or tears that will
diminish the life of the hose. Because of this, a life-sensing capability to determine structural failures or possible leaks
in hoses would be beneficial. Active health monitoring of hydraulic hoses can be accomplished with a capacitive
control circuit when integrated into the layers of the hose material. Testing of this method has shown positive results in
noticing changes to the hose structure before complete integrity is lost. Recent developments in the control circuit when
used in other applications indicate that the capacitive health monitoring can be adapted for a number of different
polymers and structural arrangements.
Active Logics as Components in Safety-related Circuits
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
J. Barg and G. Homann,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 113-124,
März 2010
view abstract
This paper shows that by using active logics, a higher degree of safety can be guaranteed. As opposed to passive logic valves, the safety behavior is only determined by the control of the valve or the pilot valve. Estimation of the diagnostic coverage is less difficult. Systematic errors are reduced. In two case studies, circuits with passive logic valves and active logics are presented and their safety behavior is explained and compared.
ACTIVE LUBRICATION FOR REDUCING WEAR AND VIBRATION – A COMBINATION OF FLUID POWER CONTROL AND TRIBOLOGY
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
R. Nicoletti and I. Ferreira Santos,
2002, Juli 2002
view abstract
The use of fluid power to reduce and control rotor vibration in rotating machines is investigated. An
active hybrid bearing is studied, whose main objective is to reduce wear and vibration between rotating
and stationary machinery parts. By injecting pressurised oil into the oil film, through orifices machined in
the bearing pads, one can alter the machine dynamic characteristics, thus enhancing its operational range.
A mathematical model of the rotor-bearing system, as well as of the hydraulic system, is presented.
Numerical results of the system frequency response show good agreement with experiment, and
simulations show the feasibility of controlling shaft vibration through this active device.
Active Regeneration Load Sensing: A Simulated Comparison with Traditional Load Sensing System in Excavators Working Cycle
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
E. Leati and P. Marani and G. Ansaloni and R. Paoluzzi,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 103-115,
März 2010
view abstract
Load sensing with Active Regeneration System is a patented technology that can be applied to multiactuator hydraulic systems, in particular mobile machinery such excavators, loaders and tractors. This hydraulic system can achieve considerable energy saving in different working situations compared with traditional Load Sensing System, by mean of an optimized flow regeneration between actuators.
Regeneration in fact permits to actively use pressure drops usually wasted in local compensator (in case of multiple actuation) or dissipated over control valves (in case of overrunning loads). The system is supervised by an electronic unit that controls regeneration through electro-hydraulic valves. To evaluate benefits and drawbacks of the Active Regeneration System, AMESim™ based modeling and simulation of the two mentioned systems has been performed. The aim of this simulation is to compare the performance of a simplified version of Active Regeneration System, applied to boom and slew actuators, with traditional Load Sensing both in terms of control and energy use. Numerical testing procedure consists on inverse dynamic simulation of the excavator applied to a typical trench digging cycle.
Active Spindle Bearing Device for Chatter Control within Milling Machines
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
T. Kohmäscher and H. Murrenhoff,
2004,
pp. 281-289,
Juni 2004
view abstract
machine structure. These vibrations are called chattering and lead to a poor machined surface and an
additional load for all machine components. To prevent the machine from chattering either the cutting depth
or the cutting speed is reduced, which also lowers the efficiency of the cutting process.
Within the collaborative research center 368 “Autonomous Production Cells”, IFAS is involved in the
development of an actively supported spindle-unit to damp chattering. The cell should be capable of
performing complex machining operations faultlessly and reliably over a longer period of time with a
maximum degree of independence [SFB368, 1999].
The special layout of the hydraulic actuator results in a high dynamic and stiffness, little need for space and
a possible displacement of five tenth of a millimeter. Using this principle should reduce the disturbing
vibrations without reducing the cutting speed or the cutting depth in order to maintain a high metal removal
rate.
Active Structural Control of Hydraulically Supported Machinery
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
K. Heiskanen and J. Juhala and M. Pietola,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 289-301,
November 2003
view abstract
In this paper the effect of uncertainty on modeling and control of flexible structure using hydraulic actuator is discussed. Variations between the natural frequencies of the structure and the nominal model are determined experimentally and the resulting uncertainty measures are used as a guideline for robust vibration control of the structure.
To guarantee the closed loop robustness and performance despite of the uncertainty in the controlled modes and to reduce the risk of spillover instability of the high frequency modes a nonparametric multiplicative uncertainty description is used in the control design.
Controllers are synthesized for varying levels of multiplicative uncertainty and the resulting closed loop robustness is analyzed using structured singular value and D-K iteration. Results show significant vibration attenuation in the frequency range of interest.
Active systems for noise reduction and efficiency improvement of axial piston pumps
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
T. Nafz and H. Murrenhoff and R. Rudik,
2008,
pp. 327-340,
September 2008
view abstract
The development of hydraulic pumps will more and more focus on fuel efficiency and noise emissions. Nowadays, common methods to reduce noise and flow ripple in axial piston pumps are to use grooves or boreholes in the valve plate, and more recently, the use of pre-compression volumes (PCV). Whenever operating parameters such as speed, delivery pressure and pump displacement change, those geometrically fixed methods no longer achieve the optimum in noise and flow ripple reduction. Therefore adjustable systems, such as variable valve plate timing or check valves have been investigated in the past, but none of these systems made it into series production. In this paper, formerly investigated adjustable systems are presented and their advantages and disadvantages are discussed. From a current point of view, systems using control valves combined with the recently available high speed measurement and control devices provide the most promising systems. Using AMESim, detailed simulations of such systems were made. Changes in flow ripple, axial forces, swash plate torque and efficiency are presented and discussed at different operating points.
Active Vibration Damping for Off-Road Vehicles using Valveless Linear Actuators
SAE Conference 2004, Chicago, IL, USA
R. Rahmfeld, M. Ivantysynova, B. Eggers,
2004,
view abstract
This paper deals with the use of a displacement controlled
linear actuator for active oscillation damping of
off-road machine structure. Aim is the development of
system solutions and control concepts for the simultaneous
use of displacement controlled (valveless) hydraulic
actuators basing on single rod cylinder for the active oscillation damping of off-road machine structure and for
the control of the working hydraulics movement. Thereby,
the productivity of the machine and the operator
comfort will be improved.
Actuation Force Control of Ca.U.M.Ha. Robotic Hand through PWM Modulated Pneumatic Digital Valves
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. Figliolini and P. Rea,
2004,
pp. 149-156,
Juni 2004
view abstract
This paper deals with a preliminary design of an actuation force control system of Ca.U.M.Ha.
(Cassino -Underactuated-Multifinger-Hand) robotic hand through PWM (Pulse-Width-
Modulation) modulated pneumatic digital valves. In particular, Ca.U.M.Ha. is provided of four
underactuated finger mechanisms and a simplified contrasting thumb, where each of them is
actuated through a pneumatic cylinder. A first lay-out of the electro-pneumatic circuit for
controlling the actuation force of Ca.U.M.Ha. is proposed, while particular attention is devoted to
the design and test of a closed- loop pressure control, which is obtained by using two PWM
modulated pneumatic digital valves. Some experimental results are shown.
Adaptive active attenuation of narrow-band fluid borne noise in a simple hydraulic system
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
Lin Wang and Nigel Johnston,
2008,
pp. 355-368,
September 2008
view abstract
This paper describes the active cancellation of fluid bome noise for several harmomc orders caused by a pump in a simple hydraulic system. A servo valve is applied as an actuator, which generates an anti-noise signal in real time. The filtered reference least mean square (FXLMS) adaptive control method with a notch adaptive filter is used. It was found that ripple reflection from both ends of the hydraulic circuit affected the performance and stability of the cancellation method. In order to execute the cancellation without any prior information about the dynamics of the hydraulic system, the online secondary path identification method was used. For efficiency and robustness, a fast block LMS (FBLMS) online secondary path identification algorithm was applied to give fast adaptive performance. However, an auxiliary white-noise signal applied to the system for this on-line method may increase residual noise.
In addition to the experiments, simulations of the active cancellation system were performed. The dynamic behaviour of the system was modelled using the method of characteristics (MOC). It was found experimentally that selected harmonics of fluid-borne noise could be attenuated by about 20dB under normal working conditions.
Adaptive Continuously Variable Compression Braking Control for Heavy-Duty Vehicles
Maria Druzhinina and Anna Stefanopoulou and Lasse Moklegaard,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 406-414,
September 2002
view abstract
Modern heavy-duty vehicles are equipped with compression braking mechanisms that augment their braking capability and reduce wear of the conventional friction brakes. In this paper we consider a heavy-duty vehicle equipped with a continuously variable compression braking mechanism. The variability of the compression braking torque is achieved through controlling a secondary opening of the exhaust valve of the vehicle's turbocharged diesel engine using a variable valve timing actuator. A model reference adaptive controller is designed to ensure good vehicle speed tracking performance in brake-by-wire driving scenarios in presence of large payload and road grade variations. The adaptive controller is integrated with backstepping procedure to account for compression braking actuator dynamics, with observers for various unmeasured quantities and with compensation schemes for actuator saturation. In addition to speed tracking, the vehicle mass and road grade are simultaneously estimated if persistence of excitation-type conditions hold. The final version of the controller is successfully evaluated on a high order crank angle model of a vehicle with a six-cylinder engine.
Adaptive Control for Improved Efficiency of Hydraulic Systems for High Speed Tilting Trains
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
G. Jacazio and D. Risso and M. Sorli and L. Tomassini,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 485-496,
März 2010
view abstract
Tilting trains are equipped with an actuation system that allows them to increase the service speed in curves and thus to optimize their running times without any need to upgrade existing infrastructures. The hydraulic tilting system in use today has an unnecessary power dissipation during 95 % of its service time since the pressure of the supply line is kept at a constant value that must be high enough to guarantee the performances required on the most severe track at very low temperature when the pressure drops are greater. In this paper is shown an innovative adaptive pressure system where the pump compensation pressure varies as a function of the required tilt angle, known in advance, and the outside temperature. A dynamic model of the hydraulic tilting system and the control unit has been developed and a significant energy saving on two specific tracks has been demonstrated.
Adaptive control of an electrohydraulic servo system utilizing online estimate of its natural frequency
H. Yanada and K. Furuta,
In Mechatronics,
2007,
volume 17,
pp. 337-343,
view abstract
This paper deals with online parameter estimation of an electrohydraulic servo (EHS) system and with adaptive control of the EHS system utilizing the parameter estimated online. In this study, the natural frequency of the EHS system is estimated using pressure sensors based on the equation of motion and equation of continuity, and the estimate of the natural frequency ist utilized to enhance the robustness of the EHS system combined with a parallel feedforward compensator (PFC). The optimal value of one of the PFC parameters is strongly influenced by the natural frequency of the EHS system and is adaptivley varied using the estimate of the natural frequency. It is shown that the natural frequency of the EHS system can be estimated relativley accurately using the method proposed, and that the robustness of the EHS system to the plant parameter variations can be enhanced by adaptively varying the PFC parameter.
Adaptive Control of Mechanical Gas Face Seals With Rotor Runout and Static Stator Misalignment
Haojiong Zhang and Robert G. Landers and Brad A. Miller,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
Juli 2010
view abstract
This paper presents a control methodology that utilizes a robust model reference adaptive control technique to regulate the dynamic behavior of a coned mechanical gas face seal system in a flexibly mounted stator configuration. Individual adaptive controllers are designed for the three stator rigid body degrees of freedom based on the linear portions of their respective equations of motion. The force and moments generated within the gas film are estimated using Kalman filter-based estimators and directly cancelled in the control algorithm using offset control signals. The estimation errors are considered as bounded disturbances to the seal system and are taken into account by the robust adaptive controllers. Simulation results show that the controllers effectively stabilize the stator motion and control the stator tilts to synchronously track the rotor runout with near-zero relative misalignment magnitude and phase shift, thus, minimizing gas leakage.
Adaptive Control of Water Hydraulic Servo Motor System –Rotational Angle and Speed Control–
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
K. Ito and H. Takahashi and S. Ikeo,
2007,
volume 1,
pp. 77-88,
Mai 2007
view abstract
With the recently increased concerns on global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic and pneumatic drive systems. However,
the main problems for precise control of a water hydraulic servo motor system are steady state errors and overshoot due to its large friction torque in the low speed range.
These accounts for the development of a strategy to compensate for uncertainties in the system and to ensure a closed-loop system maintain its specified performance.
In this paper, a model reference adaptive control (MRAC) was applied to a water hydraulic servo motor system. The MRAC system can admit parameter uncertainties by tuning the controller parameters depending on the error between a plant output and the reference signal given by the designer. The experimental results show that while the MRAC proved not to be applicable to the rotational angle control, this controller achieves good speed control performance.
Adaptive Control With Asymptotic Tracking Performance and Its Application to an Electro-Hydraulic Servo System
Zongxuan Sun and Tsu-Chin Tsao,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 188-195,
März 2000
view abstract
This paper presents a discrete-time adaptive controller, which incorporates internal model principle for asymptotic tracking performance of systems with parametric uncertainties, unmodeled dynamics and disturbances. Global stability and tracking performance of the adaptive system are derived under conditions on the system's stabilizability and bounds of noise and unmodeled dynamics. It is shown that asymptotic tracking can be achieved while the unmodeled dynamics and disturbances exist. The adaptive algorithm is applied to an electrohydraulic servo system for periodic trajectory tracking and disturbance rejection. Experimental results based on an eighth-order adaptive system updated at 2560 Hz demonstrate the adaptive system's ability in high bandwidth tracking performance under effects of system variations and finite word length real-time computation.
Adaptive Output Force Tracking Control of Hydraulic Cylinders With Applications to Robot Manipulators
Wen-Hong Zhu and Jean-Claude Piedboeuf,
In Journal of Dynamic Systems, Measurement, and Control,
2005,
volume 127,
pp. 206-217,
Juni 2005
view abstract
An adaptive output force control scheme for hydraulic cylinders is proposed by using direct output force measurement through loadcells. Due to the large and somewhat uncertain piston friction force, cylinder chamber pressure control with Coulomb-viscous friction prediction may not be sufficient enough to achieve a precise output force control. In the proposed approach, the output force error resulting from direct measurement is used not only for feedback control, but also to update the parameters of an appropriate friction model which includes the Coulomb-viscous friction force in sliding motion and the output force dependent friction force in presliding motion. The L2 and L[infinity] stability is guaranteed for both the pressure force error and the output force error. Under bounded desired output force and its derivative, asymptotic stability of both the pressure force error and the output force error is also guaranteed. The experimental results demonstrate that a good pressure force control system does not necessarily guarantee a good output force control, and that adaptive friction compensation is superior to fixed-parameter friction compensation. The output force control transfer functions of a robot joint driven by two hydraulic cylinders in pull–pull configuration are limited by ±1.5 dB up to 20 Hz, tested in free motion and in rigid constraint. The excellent output force (joint torque) control performance implies the dynamic equivalency between a hydraulic cylinder and an electrically-driven motor within the prespecified bandwidth. This allows to emulate an electrically-driven robot by a hydraulic robot.
Adaptive Repetitive Control Design with Application to an Electrohydraulic Servo
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
Z. Sun and T.-C. Tsao,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 39-53,
November 1997
view abstract
This paper addresses the discrete-time adaptive control design which incorporates internal model principle for asymptotic tracking performance of systems with parametric uncertainties, unmodeled dynamics and noise. The indirect adaptive control system applies projection or least squares parameter adaptation algorithm with dead zone, and frozen time stabilizing control. The global stability of the system is ensured under certain assumptions. The adaptive algorithm is applied to an electrohydraulic servo with periodic disturbances and reference trajectory. A frozen time stabilizing repetitive control is applied in parallel to the parameter adaptation algorithm. Experimental results show that the adaptive systems can tolerate parameter mismatch and unmodeled dynamics while maintaining stability and asymptotic tracking performance.
Adaptive Robust Control of Variable Displacement Pumps
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
L. Wang and W. J. Book,
2010,
volume 1,
pp. 165-175,
Juni 2010
view abstract
In this paper, we propose a control approach, which combine singular perturbation theory with recursive least square
method, applied to displacement controlled actuators. By this approach, the hydraulic system is simplified and control
algorithm is robust to variations in the bulk modulus, thus it is feasible for the engineering practise. The scheme shows
robustness when the system suffers from measurement noise and has a fast parameter convergence rate.
A Develop of Hydraulic Controlling Device of Working Portion in Laser Leveling Machine
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Mingliang and M. Enrong and T. Yu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 158-162,
April 2005
view abstract
The leveling precision of the laser land leveling machine mainly depends on the hydraulic controlling device. The optimized power matching and perfect work characteristics of the hydraulic system are of great importance in practical application. Based on the hydraulic system study on the machines at present in the world, according to the style, the characteristics of middle power tractor hydraulic system often used in our country, a hydraulic controlling device with simple structure for the laser land leveling machine is developed. It has been testified through experiment that it has perfect static and dynamic properties as well as high efficiency, less power consumption and better working stability without static spade drop.
A DRIVING DYNAMICS MODEL FOR OFF-ROAD VEHICLES WITH HYDROSTATIC DRIVETRAIN
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
A. Schumacher,
2006,
volume 2,
pp. 345-356,
Juni 2006
view abstract
Hydrostatic drivetrains are often used in off-road machinery like construction, building and agricultural machines.
The usage of complete vehicle simulation for agricultural machines is getting more and more important. But the
complete vehicle simulation of agricultural machines causes special problems compared to standard vehicle
simulations (e.g. car, truck…). For off-road vehicles the interaction between the tyre and the ground is important and
the knowledge about tyre parameters is very slight.
To examine the potential and the quality of a driving dynamics simulation for off-road vehicles with hydrostatic
drivetrain a computer simulation model of a self-propelled sprayer has been programmed at the Institute of
Agricultural Machinery and Fluid Power (ILF). Key point of the simulation is the driving dynamic of the vehicle on
different surfaces. With this simulation new features for the vehicle can be tested (e.g. a traction control system for
the hydrostatic drivetrain).
First results of the verification show a very good quality. Therefore it can be assumed that the model will be a
powerful tool for the developing process of hydraulic systems and electronic control units.
Advanced Modeling of Hydro-Mechanical Powersplit Transmissions
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
T. Kohmäscher and H. Murrenhoff,
2010,
volume 1,
pp. 23-33,
Juni 2010
view abstract
The market for mobile hydraulic applications clearly indicates the increasing importance of energy and fuel efficiency.
Both became important characteristics of components, sub-systems, and machines and are considered an important
argument during sales and negotiations. This trend was greatly pushed by increasing fuel prices and tightened
emission regulations, e.g. Tier IV. Drive line efficiency can be greatly improved by application of hydro-mechanical
power split transmissions (HMTs) in comparison to power shift transmissions (with or without torque converter) or
hydrostatic transmission solutions. Increased system complexity requires simulation to become an essential part of the development process. This paper introduces a simulation approach for power split transmissions and focuses on the
modeling of compound planetary gears which are an essential component for HMTs. Adequate modeling of the
mechanical and hydrostatic power branches requires both the accurate prediction of functionality and power losses.
Advanced Sealing Systems for Modern Commercial Aircraft Hydraulic Systems
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
T. Andersen,
2007,
volume 1,
pp. 135-151,
Mai 2007
view abstract
This paper describes the evolution of hydraulic flight control systems for military and civil aircraft as well as the influence of this development on the sealing systems applied in the hydraulic actuators. Introduction of Fly-By-Wire, and unstable aircraft designs, controlled via a flight computer, has increased the stroke frequency, while the demands for long maintenance free service life of new aircraft has increased the expected service
life of the sealing system. The corresponding evolution in the sealing systems for military and civil aircraft is discussed.
ADVANTAGES IN USING LS AND LUDV SYSTEMS TO CONTROL THE CRAWLER DOZER BLADE
Developments in Fluid Power Control of Machinery and Manipulators - 2nd International Scientific Forum, Cracow, Poland
ISBN: 83-86219-71-8,
M. Markowski,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 209-215,
Juni 2000
view abstract
Crawler dozers are intended to make shallow excavations, to trans-mould the ground surfaces, to trans-locate over minor distances. The dozer is composed of the crawler dozer and of the blade. Controlling of blade movements in crawler
dozers is performed by means of the hydraulic system. The main blade movements are: lifting, lowering, lowering with the "floating" function and tilting. The "floating" function is free lowering of the blade, thus uniting the
piston-rod space and non-rod space of blade lifting cylinders. It is used in smoothing of the ground surface during the dozer ride-back and to quick lowering
of the blade from its carrying position to the ground line at the Start of the working cycle, thus shortening its time.
The improvement of hydraulic parameters of the blade control hydraulic system in reduction of its energy consumptivity and advancement of the controlling exactitude are obtained after application of the LS system.
Advantages of Parallel Hydraulic Hybrid Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
V. Duray and C. Arneson and R. Isaacs and M. Stoner,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 421-432,
März 2010
view abstract
This paper discusses technical advantages of parallel hydraulic hybrid systems. These advantages are best leveraged in severe duty applications such as refuse trucks which are characterized by heavy gross vehicle weights and frequent stop-and-go duty cycles. Hydraulics offers a distinct advantage in the hybrid landscape due to superior power density as compared to competing technologies. Power density enables more energy to be captured and released during a vehicle braking event. When a hydraulic hybrid is a parallel system that supplements a conventional drive train, a fleet owner realizes additional advantages over a series hybrid system that replaces the drive train. These advantages include customization of performance characteristics, the opportunity to retrofit the hybrid onto an existing vehicle, and increased mission reliability. Examples and test data for this paper were taken from the recent development of Eaton’s Hydraulic Launch Assist™, or HLA® system, a parallel hydraulic hybrid system for the refuse industry.
A Dynamic Model of an Electropneumatic Valve Actuator for Internal Combustion Engines
Jia Ma and Guoming G. Zhu and Harold Schock,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
März 2010
view abstract
This paper presents a detailed model of a novel electropneumatic valve actuator for both engine intake and exhaust valves. The valve actuator's main function is to provide variable valve timing and variable lift capabilities in an internal combustion engine. The pneumatic actuation is used to open the valve and the hydraulic latch mechanism is used to hold the valve open and to reduce valve seating velocity. This combination of pneumatic and hydraulic mechanisms allows the system to operate under low pressure with an energy saving mode. It extracts the full pneumatic energy to open the valve and use the hydraulic latch that consumes almost no energy to hold the valve open. A system dynamics analysis is provided and followed by mathematical modeling. This dynamic model is based on Newton's law, mass conservation, and thermodynamic principles. The air compressibility and liquid compressibility in the hydraulic latch are modeled, and the discontinuous nonlinearity of the compressible flow due to choking is carefully considered. Provision is made for the nonlinear motion of the mechanical components due to the physical constraints. Validation experiments were performed on a Ford 4.6 l four-valve V8 engine head with different air supply pressures and different solenoid pulse inputs. The simulation responses agreed with the experimental results at different engine speeds and supply air pressures.
A dynamic study of an air cylinder for load positioning control
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
S. C. Fok and Y. P. Leow,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 143-149,
November 1997
view abstract
This paper analyses the linearised dynamic characteristics of an air cylinder system for continuous load positioning control. First, the mathematical model of the cylinder system is derived based on a typical electropneumatic valve whose flow characteristics are dependent on both the applied voltage and pressure. Next, the mathematical model associated with a servovalve whose mass flow rate is proportional to the applied voltage is developed. From the mathematical models, the paper discusses the effects of the valves and the load positions on the air cylinder system dynamics. Some simulation and experimental results are given to illustrate the analysis for the control of different start/stop load positioning.
A FINITE VOLUME CENTRAL DIFFERENCING SCHEME FOR SIMULATION OF THE SHUT DOWN PROCEDURE OF A HYDRAULIC SYSTEM
K. Mazaheri and R. H. Farahani,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 17-27,
August 2002
view abstract
A new central differencing finite volume scheme is investigated for solution of unsteady hydraulic problems as water
hammer in pipe systems. Special time stepping procedure similar to Runge-Kutta algorithm is used to stabilize this
second order scheme. It is monotonized by adding dissipative terms including second and fourth derivatives of the conserved
variables, with coefficients proportional to derivatives of pressure or volumetric flow, which keeps the second
order of accuracy in smooth flow regions. The one-dimensional unsteady incompressible equations are solved for a water
hammer situation, and results are compared to existing analytical solutions. Results are also compared with numerical
results of classical characteristic method, which is proved to be fairly accurate. The scheme could easily be generalized
to two-dimensional case. Finally this procedure is used for analysis of the shut down procedure of a hydraulic system.
Components of the system are modeled and effects of important parameters on the performance are studied.
A Fourier-Galerkin-Newten method for nonlinear transmission line problems
Power Transmission and Motion Control, Bath, UK, 12-14 September 2007
ISBN: 978-0-86197-140-4,
H. Kogler, B. Manhartsgruber and R. Haas,
PTMC Bath,
ed. Dr D N Johnston and Professor A R Plummer,
2007,
volume 1,
pp. 217-227,
September 2007
view abstract
The problem of pressure and flow-rate oscillations in periodically excited transmission line
systems arises in a number of fluid power applications. The fluid-borne noise problem in
the suction and delivery lines of pumps has been studied by a large number of authors in
the past. More recent applications can be found in the simulation of common-rail diesel
injection and hydraulic valve actuation systems in the automotive industry. In the case of
laminar flow with small pressure oscillations around a stationary operating point, a linear
model can be used and the system answer to periodic excitations can be computed efficiently
in the frequency domain. Even in the case of nonlinear boundary conditions, e.g. a valve
with a quadratic pressure drop, combined time and frequency domain methods have been
used by a number of authors in order to maintain the benefits of frequency domain modelling
of transmission lines. A much harder problem arises if the nonlinearity is distributed along
the transmission line. In this paper, a Fourier-Galerkin-Newton method is applied to laminar
transmission line flow with a nonlinear compressibility law. The viscous effects are modelled
by the linear, frequency dependent friction model in the form due to Kagawa et al. For the
spatial discretisation a Galerkin approach with a staggered grid is taken from literature. In
order to treat periodic problems efficiently, the solution is parameterised by Fourier series.
The approach results in a large scale, nonlinear system of equations to be solved for the
periodic system response to periodic excitations.
A FULL FOUR-QUADRANT HYDRAULIC STEERING ACTUATOR APPLIED TO A FULLY AUTOMATIC PASSENGER VEHICLE PARKING SYSTEM
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
P. Degerman and M. Rösth and J.-O. Palmberg,
2006,
volume 2,
pp. 387-396,
Juni 2006
view abstract
This project describes how the Active Pinion hydraulic steering system can be used to replace a electric power steering actuator in the Parking Pilot automatic parking system. Customer demand for fully or semi automatic parking systems in passenger cars, are getting higher with increased cost of parking related body damage repair coupled with restricted rearward sight and the larger dimensions of modern cars. This, however, puts new demands on the steering actuator. An automatic parking system requires full control of the steering servo, which is not possible with current hydraulic actuators. Instead these systems have to rely on electric servos which allow for the needed controllability. All current electric steering servos have the drawback that it is impossible to use them on anything but small or medium sized cars. Since a parking system can be seen as a premium accessory, which is more likely to attract customers who buy larger cars, this is a major hindrance for the success of automatic parking systems. A solution to the problem is to construct a controllable variant of the hydraulic steering servo, the Active Pinion. In this concept a small electric pilot motor is added to the traditional hydraulic valve, which adds one additional degree of freedom to the servo, accomplishing full four-quadrant operations. The project discusses how the Active Pinion concept is introduced in the Parking Pilot parking system and how different demands on the parking system relates to the performance of the actuator. The parking system is installed in a prototype car and simulation of the Active Pinion concept is accomplished with HWIL simulation in a load simulator.
A fully-coupled thermo-elastic model for the rotating kit of axial piston machines
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Pelosi and M. Zecchi and M. Ivantysynova,
2010,
pp. 217-233,
September 2010
view abstract
The lubricating gaps of piston machines represent the main source of energy dissipation, fulfilling simultaneously a sealing and bearing function. The goal of the authors’ research is to predict with a high level of confidence the fluid film thickness, the gap flow, the load carrying ability and the energy dissipation in those lubricating gaps. The paper presents a fully coupled fluid-structure and thermal model connecting the piston/cylinder and the cylinder block/valve plate gaps. The lubricating gaps numerical model considers the squeeze film effect due to the micro-motion of the moveable parts and simultaneously the change of fluid film thickness due to the pressure and thermal deformation of the solid parts. Heat transfer models allow obtaining the fully non-isothermal solution of the fluid flow, based on finite volume models of the mechanical bodies. The model is composed of two fully coupled modules. The first module integrates the energy equation in both cylinder block/valve plate and piston/cylinder gaps, calculating the heat fluxes generated by the viscous dissipation. These heat fluxes are then used by the second module for solving the entire temperature field in the cylinder block, bushings and pistons. A new set of surface temperature boundary conditions is thus generated for a further and more precise integration of the energy equation. Therefore, a complete thermal analysis and three dimensional temperature distribution of the entire rotating kit is obtained considering the simultaneous contribution to the heat transferred through the solid part from the cylinder block/valve plate gap and all the piston/cylinder gaps. The temperature distribution information is further used to calculate thermal stresses and the consequent thermal expansion of the bodies, predicting the impact on piston/cylinder and cylinder block/valve plate fluid film thickness.
A FUZZY NEURAL NETWORK APPROACH TO MODEL HYDRAULIC COMPONENT FROM INPUT/OUTPUT DATA
W. Xiang and S. C. Fok and F. F. Yap,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 37-47,
März 2001
view abstract
The knowledge of dynamics of hydraulic components are vital for the virtual prototyping of fluid power systems.
This paper proposes a fuzzy neural network approach to model the behavior of a hydraulic component from its inputoutput
data. The main advantage of this approach is that the network structure can be determined based on the analysis
of the input variables to output response, without trial and error, network pruning or network growing techniques. The
process involves resolving the significant inputs through an analysis of their effects with respect to the output. The
number of fuzzy rules is determined based on partitioning of the input-output space. The number of significant inputs
and the number of fuzzy rules together define the fuzzy neural network structure. A hydraulic pressure relief valve is
used to demonstrate the proposed approach. The results indicate that the structure of the fuzzy neural network determined
based on the proposed approach can effectively model the dynamics of the relief valve. This work constitutes
initial effort towards determining the structure of neural networks based on the analysis of input-output data.
A Hardware-in-the-Loop Spacecraft Docking Simulation System and Its Stability Analysis
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Q. Huang and S. Zhang and J. Hun and H. Jiang and Z. Ye,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 799-802,
April 2005
view abstract
A ground-base simulation system for the spacecraft docking by using the hardware-in-the loop simulation with electro-hydraulic driven parallel platform is introduced. In particular, simulation of on-orbit docking process of a chaser and target vehicles to test the capability of the docking mechanisms is targeted. Principle and components of the simulation system are presented in detail. The relative motion during the buffering process after docking contact of two vehicles is
simplified and modeled in decoupled degree. The stability of the simulation system on one degree is analyzed. Some beneficial conclusions, which can be used in designing docking mechanisms, are obtained.
A High-Order Large Eddy Simulation Method for Fluid-Power Components
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
D. Shetty and K. Anupindi and S. H. Frankel,
2010,
volume 1,
pp. 215-226,
Juni 2010
view abstract
A high-order large eddy simulation (LES) approach for numerical integration of the incompressible Navier-Stokes
equations is combined with the fictitious domain method to handle complex geometries, while maintaining the
computational simplicity of structured Cartesian grids, and applied to several benchmark and industrially inspired
cases to demonstrate the ability of the approach for modeling flow through fluid power devices. Spatial discretization
is based on the finite-difference method and combines the use of the 5th-order weighted essentially non-oscillatory
(WENO) scheme for convection with 4th-order summation-by-parts centered differences operators for diffusion. A
projection method is employed to handle pressure-velocity coupling and the MUDPACK multigrid solver is used to
solve the resulting Poisson equation. Time discretization is achieved via high-order strongly stability preserving
Runge-Kutta methods. The code is written in Fortran90 and parallelized using OpenMP. The subgrid-scale turbulence
model is based on the non-dynamic and dynamic versions of the Vreman model and is hence applicable to fully nonhomogeneous
turbulent flows. Results are presented to demonstrate that the code, hereafter WenoHydro, is shown to
be able to reasonably accurately predict flows ranging from steady laminar flow through a curved pipe, to twodimensional
and three-dimensional lid-driven cavity flows, to steady pipe flow through an orifice, to turbulent flow
through a model valve, and flow over moving bodies. Extensions of the code to include cavitation and application of the code to industrial valves are also discussed.
A High Output-Power Piezoelectric Micropump Using Inertia of Pipe
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
K. Yoshida and Y.-O. Jung and T. Seto,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 394-397,
April 2005
view abstract
For fluid microactuators and microfactories, we had proposed a novel high output-power micropump using inertia of pipe which has an outlet pipe in place of an outlet check valve and verified the effectiveness with a fabricated micropump. To increase the output power in small size, the paper proposed a simple nonlinear mathematical model with lumped parameters and verified the effectiveness comparing the simulation and experimental results. Then, the pump structure for higher output-power was obtained through the simulations with different sizes of the pipe. Finally, micropumps were fabricated and, the validity of the pump structure was experimentally confirmed.
A High Performance Planar ECF Pump for Liquid Cooling of High Power Electronic Chips
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Yokota and W.-S. Seo and K. Yoshida and K. Edamura,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 234-237,
April 2005
view abstract
This paper presents a novel liquid cooling concept for heat rejection of high power electronic chips existing in notebook computers etc. In order to realize a liquid cooling system for the electronic chips, such as notebook CPUs, a simple planar pump using electro-conjugate fluid (ECF) is proposed, fabricated, and experimentally investigated. The ECF is a kind of dielectric and functional fluids, which generates jet flows (ECF-jets) by applying static electric field through a pair of rod-like electrodes. The ECF pump has a parallel rod-like electrode array attached on a substrate and generates ECF flows by ECF-jet in each pair of electrodes. The proposed planar ECF pump achieves no-load flow rate of 5.5 cm³/s and maximum output pressure of 7.1 kPa at an applied voltage of 2.0 kV.
A High Performance Pneumatic Force Actuator System: Part II—Nonlinear Controller Design
Edmond Richer and Yildirim Hurmuzlu,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 426-434,
September 2000
view abstract
In this article we present two nonlinear force controllers based on the sliding mode control theory. For this purpose we use the detailed mathematical model of the pneumatic system developed in the first part of the paper. The first controller is based on the complete model, and exhibits superior performance both in the numerical simulation and experiments, but requires complex online computations for the control law. The second controller neglects the valve dynamics and the time delay due to connecting tubes. The performance of this controller exhibits slight degradation for configurations with relatively short tubes, and at frequencies up to 20 Hz. At higher frequencies or when long connecting tubes are used, however, the performance exhibits significant degradation compared to the one provided by the full order controller.
A High Performance Pneumatic Force Actuator System: Part I—Nonlinear Mathematical Model
Edmond Richer and Yildirim Hurmuzlu,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 416-425,
September 2000
view abstract
In this paper, we developed a detailed mathematical model of dual action pneumatic actuators controlled with proportional spool valves. Effects of nonlinear flow through the valve, air compressibility in cylinder chambers, leakage between chambers, end of stroke inactive volume, and time delay and attenuation in the pneumatic lines were carefully considered. We performed system identification, numerical simulation, and model validation experiments for two types of air cylinders and different connecting tubes length. The mathematical model of the present article is used in a sequel article to develop high performance nonlinear pneumatic force controllers.
A Hydraulic Control Valve for PWM Actuation at 400 Hz
Power Transmission and Motion Control - PTMC 2006
B. Manhartsgruber,
2006,
pp. 373-385,
September 2006
view abstract
The concept of switching converters known from the control of electrical drives can also be applied to hydraulic control systems. A number of such concepts relies upon the pulse width modulation (PWM) of an actuator pressure by a periodically switching valve. In order to keep the good dynamic properties of valve controlled drives, the PWM frequency has to be much higher than the typical eigenfrequency of the driven mechanical system. Therefore, two major problems arise. Firstly, the pressure variations induced by the periodic switching of the consumer ports between the high and the low system pressure port have to be decoupled both at the supply side and at the consumer side to prevent excessive noise propagation and high frequency actuation of the driven mechanical system. And secondly, the switching valve has to be very fast compared to commercially available products. Furthermore, the power available for the actuation of this valve is limited in order to keep the energetic benefits provided by the switching control. In this paper, a novel valve design is presented. A prototype with a flow rating of 100 l/min at 5 bar pressure drop has been built and successfully tested. The basic design is that of a 3/3 directional control valve, with a constant high pressure supply port and a constant low pressure supply port both equipped with hydraulic accumulators. The third port is pulse width modulated between the low and the high pressure port at a frequency of approximately 400 Hz. The so called duty-cycle, i. e. the relative connection time to high pressure within one PWM period is controllable between 0 and 100 % during the PWM operation allowing for the control of a connected consumer. Besides some details on the design of this valve, the paper shows simulation results regarding the use of the prototype in a hydraulic switching converter.
A Hydraulic Energy Efficient Fast Positioning Actuator Exploiting a Hydraulic Spring Concept
Proceedings of The Eighth Scandinavian International Conference on Fluid Power, SICFP'03, Tampere, Finland
A. Plöckinger and N. Krimbacher and R. Scheidl,
2003,
volume 2,
Mai 2003
view abstract
For some applications industry is searching for very fast, powerful and energy efficient actuators. Fast positioning actuators can be used, e.g. for a punching process or for operating large and fast hydraulic switching valves. One system which is based on a fast switching actuator is Hoerbigerss so called HydroCom [4], which opens and closes suction valves of huge compressors. In contrast to classical non return valve concepts, these active suction valves provide additional control which can be utilised in several ways. In this paper a novel actuation concept is discussed (see Figure 3), the basic idea of which was already presented by N. Krimbacher [2,3]. Functionally, it features a mass spring oscillator with a latch. The spring is realised by the compressibility of hydraulic fluid in a cavity, the latch by a fast hydraulic switching main valve 1V1. We will report about the examination of the concept by a test rig (see Figure 6). It comprises the main components as shown in Figure 3 and additional valves for replenishing leakage and for energy supply, additional pressure and displacement transducers, and flow rate sensors. Control and data recording is provided by a digital signal processing system. The measurement results affirm the basic functioning and the robustness of the system. The effect of several imperfections of the system, such as leakage, fluid friction, parasitic hydraulic capacities in control lines on the system performance will be discussed. The experimental results will be compared with those of extensive simulation studies. All numerical computations have been carried out with MATLAB/SIMULINK and we have used MAPLEV for deriving analytical results. To control and monitor the test rig a digital signal processor unit (dSPACE) was used.
A Hydraulic Proportional Valve Identification Using Computational Fluid Dynamics and ARX Model
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
S. M. Hashemi and S. P. A. Tabrizi and M. Rezaee,
2006,
volume 2,
pp. 455-463,
Juni 2006
view abstract
A new method for modelling the flow through electrohydraulic proportional valve ports is described in this paper.
Single stage proportional valves are cheaper and more reliable than high accuracy multistage servo valves. However,
their use is restricted to low bandwidth applications. Better performance can be obtained if an accurate model of
proportional valves is used in electrohydraulic control system design and simulation. In the proposed method, CFD
analysis is used to solve viscous turbulent flow field through valve orifices in steady state condition. Velocity field,
pressure distribution and flow rate are obtained for different boundary conditions and orifice openings which cover all
possible states. An auto-regressive exogenous (ARX) model is employed as the system identification method. Orifice
opening and pressure difference are used as the inputs to the model and the resulting flow rate from CFD analysis is
counted as the output of the model. Considering the ARX method ability to simulate the transient processes, the
obtained model is a more accurate alternative to orifice nonlinear equation in both steady state and unsteady state
regimes. Simulation results show that ARX model output coincides with the CFD analysis results.
Air centrifugal compressors and antisurge control
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
J. Oldřich,
2008,
pp. 160-167,
September 2008
view abstract
The contribution deals with experience with development of antisurge protection algorithm for centrifuga compressor.
Company ČKD NOVÉ ENERGO produces centrifugal compressors that compress various kinds of gases like a for example air, mixtures of hydrocarbons, natural gas or hydrogen. Capacity of compressors varies at very broad boundaries. These machines are usually part of some bigger plants and so they must be very reliable. First part of this requirement is fulfilled by high-quality design and second part has to be ensured by failure-free operation.
Surge is a dangerous phenomenon, which can occur in compressor when, due to flow separation in flow part of the compressor, happens to periodic changes in its direction and consequently to pulsation which may harm the machine. Surge causes noise, vibration of machine and, consequently, surge may reduce the lifetime of the machine or in extreme case surge can cause the accident. Method described in this contribution is based on isentropic model of compression, the generalisation of all operating characteristics and their transformation into one reference dimensionless characteristic. This method is suitable both for compressor working with air and also for compressors working with various gases and its mixtures
Aircraft Hydraulic Fluid Diagnostics (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
P. Heřmánek and J. Král and J. Mašek,
2008,
pp. 214-221,
September 2008
view abstract
The main subject of this article is diagnostic of hydraulics fluids. Diagnostics is a part of maintenance which is responsible for monitoring of capacity, durability, working parameters and predicted next situations in technical life of mechanism. Diagnostics of hydraulic fluids is compare parameters on new oil with oil used in hydraulics system. Important is monitoring of limited parameters according to statement of oil producers or producers of machines. It means that manufacturer recommends the higher level of parameters for safety using of hydraulic oil. By measurement we can recognize actuality of oil. It is possible to recognize kind of attrition, situation in oil and expected technical life of oil or take decision for changing the oil.
We choose following methods for diagnostics of EXXON HyJet IV fluid:
• Appearance of hydraulic fluid
Simple and easy is color and appearance of fluid. This test can easy find big parts and content of water and other pollutions. New fluid is violet. The color is going to the dark due to attrition. From our point of view is this observation enough.
• Neutralization number
Neutralization number by clean fluid has to be lower than 0.15 mg KOH.g-1. We measured neutralization number 0.41 mg KOH.g-1. It was demonstrate decline of number by refilling of fluid. Other hydraulic fluids can have the neutralization number higher and during using the number is increasing.
• Kinematics viscosity measurement (by 40°C)
There is an influence of other fluids and adulterants or higher water contain. Average value of kinematics viscosity was 6.67 mm2.s-1. Viscosity was more in lower level of scale. It is good for pump ability, low resistance by system start, good tightness and satisfactory lubrication.
• Density measurement
Average value of density was 1004 kg.m-3. Clean fluid has tolerant range between 993 and 1066 kg.m-3. So measured value is OK.
• Water contain and conductivity measurement
Water is undesirable due to oxidations and bubbles production. For water contain measurement is it possible to use FTIR analyze. The FITR accuracy is high and shows true rate of Al, Cr, Cu, Fe, Pb, Sn, N and part of oil additives (Mg, Mo, Ca, Zn, P) and components of oil pollution Si, B, Na, K. Minimum value for hydraulics fluids is 0,3 μS. Average value of all samples was 0,78 μS.
• Automatic measurement of purity code by NAS 1638 and ISO 4406 and total impurities
Probably the most important parameter is purity code. It is observed in all measurement of different fluids. Measurement of total impurities is important for nomogram of attritions construction. Together with aggregate of code by ISO 4406 was nomogram constructed. The ISO is more suitable for nomogram construction because there is descending reduction of impurities for 1 ml of hydraulic fluid.
Output of this work is evaluation and setting of the trend observation of hydraulic fluid. Modification and compare of observed limits and suggestion of pilot project of full hydraulic system observation was the most important part of the output.
Air Release Properties of Hydraulic Fluids, Dynamic Air Release Behaviour
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
W. Bock and J. Braun and N. Puhl and H. Heinemann,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 327-340,
März 2010
view abstract
The paper shows test results of the dynamic air release behaviour of hydraulic fluids. The tests were run in a modified test equipment according to DIN ISO 9120. Test results of standard, so-called Group I mineral oil-based fluids are compared with semi-synthetic, Group III-based oils (hydrotreated base oils) and other fully synthetic hydraulic fluids. A comparison with the behaviour of lubricating and gear oils and the dynamic air release properties are shown.
A Kind of Adaptive Fuzzy-based PI AQM Algorithm
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S.-h. Xiang and B.-g. Xu and D.-z. Peng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 784-789,
April 2005
view abstract
In this paper, a kind of fuzzy adaptive PI AQM algorithm is designed by using the advantage of fuzzy theory in uncertain conditions. It is illustrated by simulations that the proposed algorithm, which robustly accommodates to various loop conditions and diversified traffic flows, can ensure the stability of package queue, accelerate the convergent velocity and decrease the overshoot of queue.
A Linearized Electrohydraulic Servovalve Model for Valve Dynamics Sensitivity Analysis and Control System Design
Dean H. Kim and Tsu-Chin Tsao,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 179-187,
März 2000
view abstract
This paper presents the derivation of a linearized model for flapper-nozzle type two-stage electrohydraulic servovalves from the nonlinear state equations. The coefficients of the linearized model are derived in terms of the valve physical parameters and fluid properties explicitly, and are useful for valve design and sensitivity analysis. When using this model structure to fit experimental frequency response data, the results render closer agreement than when using existing low order linear models. This model also suggests important servovalve dynamic properties such as the nonminimum phase zero and the transfer function relative degree, and how they relate to the valve component arrangement. Because of the small modeling errors over a wide frequency range, a high bandwidth control system can be designed. A robust performance controller is designed and implemented to demonstrate the utility of the model.
Alternating Pump Control for a Load-Sensing System
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
B. Grösbrink and T. Stamm von Baumgarten and H.-H. Harms,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 139-150,
März 2010
view abstract
The paper shows a hydraulic system suitable for mobile machines which is based on the setup of the conventional hydraulic-mechanic Load-Sensing (hm-LS). In addition to the hm-LS system, the new system possesses an electro-hydraulic (eh) pump swash plate angle controller and a hydraulic-mechanic pressure difference sensor for the measurement of the difference between pump pressure and maximum load pressure. In operating ranges with small swash plate angles the new system is controlled by the hm volume flow controller with the necessary precision. At large volume flow and hence large power demand, the system is controlled by the eh pump controller with an improved energetic and dynamic behaviour. In this contribution the dynamic system transfer behaviour, in particular during a changing pump controller and a comparison of the energetic behaviour between the hm-LS and the system with alternating pump controllers is shown by means of measurements with a test rig.
Alternative Two Valves Control Concept For Hydraulic Drive (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
P. Koňařík,
2008,
pp. 90-97,
September 2008
view abstract
Paper presents alternative two valves control concept for hydraulic drive as a
functional exchange of a classical three-position four-way valve for two 3/3-way valves.
Presented concept practically solves problem of dynamic calculation of two independent
action control values on control valves by the help of real behavior knowledge of each valves.
These behaviors are generally described by static flow characteristics that can be measured
on each of valves via simple measuring routines using approximation and interpolation
methods.
Independent control of each control valve allows realizing a range of control concepts
focusing on specific hydraulic drive control requirements. For example one of possible
hydraulic drive control concept allows bringing hydraulic circuit behavior and its
unsymmetrical pressure and flow characteristics of circuit realization with one side piston of
hydromotor to behavior of hydraulic circuit with symmetrical piston of hydromotor with
respect to symmetrical pressure and flow characteristics. The others benefits are higher
operability of hydromotor, protection from cavitations effects or potential energy savings.
Nonlinearities and unsymmetrical behavior can be compensated by suitable control due to
another degree of freedom in control of hydraulic drive and due to new possibilities in control
then. Found control concepts and approximated valves characteristics can be economy
described through coefficients and consequently for practical realization used in
microprocessor unit to control of whole hydraulic drive system under user required criteria.
All measurements, simulations, verification and theirs comparisons as well as parameters
tuning and design of control concepts of hydraulic drive were designed and made in
Matlab/Simulink environment connected with I/O real-time simulator dSPACE system.
A Mathematical Model of Movable Component in Single Screw Compressor
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Zhenyu and T. Guoliang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 276-279,
April 2005
view abstract
A general mathematical model of movable component in single screw compressor is established in this paper. The method considers that the mathematical of compressor is determined by the profile of tooth gate which is one of the two key movable components in the single screw compressor. The screw rotor's surface can be obtained by an envelop of the one Parameter family of gate tooth. Based on the method, the solid model of the compressor is achieved by matlab language and Pro/E Software. The mathematical model not only provide the data code for rapid Prototype, but also is the foundation of the CFD analysis.
A METHOD FOR NOISE REDUCTION IN HYDRAULIC LINES
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
J. Wang and M. Paidoussis, L. Mongeau,
2008,
pp. 52-62,
Juli 2008
view abstract
Sound transmission in hydraulic lines is of great importance in many engineering applications. Sound produced from
hydraulic pumps may be radiated to the environment, and transmitted between components through flexible hoses, often
modelled as shell-type structures. Noise in hydraulic lines filled with flowing fluid is generated through complex fluidstructure interactions. In this project, a conceptual muffler configuration consisting of a set of alternating shell
segments was investigated. By varying parameters such as material properties and the hose dimensions, both sound
and structural waves in the hoses were attenuated through the creation of stop bands at the operating frequency.
In this paper, thick- and thin-shell theories were investigated. It was found that for low frequency or long wavelengths, consistent results were obtained by the two theories. The transfer matrix method in conjunction with Floquet theory was used in analyzing the periodic shell system. Preliminary results showed that numerous stop bands appear and
substantial attenuation can be achieved. The first two natural frequencies of a shell with and without fluid loading were
computed. Their values agree with similar results from other researchers.
A Method to the Forward Solution of the General 6-DOF Parallel Platform Based on Generalized Force Principle
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Li Qiang and W. Xuanyin and L. Rong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 836-839,
April 2005
view abstract
In this paper, a method to the forward solution of the general 6-dof parallel platform is studied based on generalized force principle. By this method, we can get the expression of the real-time forward solution of the general 6-dof parallel platform. At last, the paper puts forward a preliminary plan for test. The plan based on the principle also is a new plan to test the position/force closed-loop control of the platform.
A Modified Orifice Flow Formula for Numerical Simulation of Fluid Power Systems
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
A. Ellman and R. Piché,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 59-63,
November 1996
view abstract
The conventional turbulent orifice flow formula has an infinite derivative when the pressure drop is zero. This can cause ODE solvers to crash during numerical simulation of fluid power circuits. A two-regime orifice flow formula is proposed in which an empirical polynomial laminar flow formula is used for small pressure differences. The proposed formula has a smooth transition between laminar and turbulent regimes and does not have a singular derivative, and so is well-suited for accurate and trouble-free simulation.
A Modular Design Scheme for Servo-Drives Control, with Application to Pneumatic System
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
S. Refaat and P. Dransfield,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 137-141,
November 1997
view abstract
A unified approach for control system design of single input-single output (SISO) mechatronic systems is presented. The approach is based on combining off-line identification, pole placement, composite adaptive control, sliding control, static
nonlinearity compensation, gain scheduling, and plant on-line parameter estimation, each as a module. The approach is presented as modules added one after the other. Consequently, the effect of each of the modules and its integration
with the other modules are demonstrated. The automation and plant-independence of these design steps are also shown. A nonlinear pneumatic long cylinder servo-system
is used to test the approach experimentally. The approach is equally suitable for electric or hydraulic servo-drive technologies, in both position control and force control applications.
A Multiplicative-recursive Filter and Linearization Scheme
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
U. Walter,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 471-484,
März 2010
view abstract
The control of hydraulic systems requires not only good theoretical knowledge in the field of hydraulics and the associated dynamic processes, but also often a generous portion of improvisation talent. When one is working under time pressure such as is typically found in industry, then the optimum closed-loop controller is not the "best and most dynamic controller", but that which quickly provides a satisfactory result.
This is the point where this alternative control structure comes into its own. The MR closed-loop controller described here offers an approach which also enables a less experienced specialist to optimise the control loop and to achieve satisfactory results. The approach breaks new ground in generating the manipulated variable. In short, the command value is divided by the actual value (command and actual value are no longer subtracted). This non-dimensional result is multiplied by the actual control variable using a recursive filter. The simple structure of this kind of adaptive controller makes it ideally suited to self-parameterisation.
A multi-sensor for monitoring the oil condition of mobile working machines in operation
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
H.-H. Harms and J. Krallmann,
2006,
pp. 81-94,
September 2006
view abstract
The main target for a development of a monitoring-system, which detects the oil condition reliably, is to extend the lifetime of the hydraulic oil, to avoid breakdowns and unplanned shutdowns, to minimize shutdowns because of maintenance and repairs, to accelerate the use of biodegradable hydraulic fluids and to compensate the higher costs by a longer lifetime. The oil sensor can measure different characteristics of oil reliably. In this case, the selection fell into two values, which can be measured with comparatively weighted averages. In a lot cases especially on agricultural tractors there is a very big problem with oil mixing by using various attachments. This mixing overlays the effect of oil ageing so that a valuation of the data could only be achieved by a human expert analysing the processes.
A MULTIVARIABLE PASSIVITY BASED CONTROL FOR AN ELECTROPNEUMATIC ACTUATOR
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
K. Turki Saied and M. Smaoui and X. Brun and D. Thomasset,
2008,
pp. 174-185,
Juli 2008
view abstract
This paper develops a systematic methodology for the control of a class of nonlinear systems and applies it to
electropneumatic system. It deals with multiple input – multiple ouput (MIMO) systems in the strict feedback form. The
approach is conceptually similar to previously developed integrator backstepping methodologies. However, unlike
some previous investigations which have relied exclusively on a Lyapunov analysis, this work presents a stability
analysis using a passivity formulation. First, the nonlinear model of the electropneumatic system is presented. A class
of modeling error is introduced and compensated for with the resulting control able to guarantee specified boundary
layer tracking. Then, the control algorithm is implemented on the pneumatic system. Finally, experimental results are
presented and discussed.
AN ACCURATE TRACKING CONTROL OF AN ELECTROPNEUMATIC ACTUATOR
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
X. Brun and D. Thomasset and E. Bideaux and S. Scavarda,
2000,
pp. 215-226,
September 2000
view abstract
Synopsis: Due to low cost, clean working environments, linear power transfer facilities and good performance, pneumatic
systems play a significant role in industrial processes. During the last twenty years, the parallel development of
pneumatic systems and control theory has lead to the implementation of modern control laws in pneumatic devices
[Edge 1997]. The aim of this paper is to present and to compare experimental results for an electropneumatic positioning
system. A classical linear control law with scheduling gains, established with the tangent linearized model, is
compared with a more sophisticated nonlinear control law based on input-output linearization [Isidori 1989].
The tests are realised with two different admissible trajectories. The first one is a trajectory with a constant stage,
which is usually used in robotic, to control painting system for example. The second one is a trajectory with constant
acceleration and deceleration stages, often used for positioning systems which carry delicate loads or dangerous liquids
in containers (as in the chemical industry). This choice of the trajectories has also to be related to a problem of
sizing. The experimental results are presented in terms of repeatability for each control law implemented on the same
device: an in line electropneumatic servo-drive. The statistical comparisons between nonlinear and linear control laws are shown in terms of static error: mean value, standard deviation value, minimum and maximum values. The precision
and the repeatability are deduced from these results. All these indicators are also processed during the dynamical
stage. The customer for choosing an appropriate control law for its desired specifications may use all these results.
An Active Suspension with Reduced Complexity
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
T. Bedarff and P. Pelz,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 393-404,
März 2010
view abstract
This paper introduces a new active hydro pneumatic suspension system (HFD) and examines the dynamic behavior of the system. The HFD is developed at the Technische Universität Darmstadt within the Collaborative Research Centre (SFB) 805, supported by Deutsche Forschungsgemeinschaft (DFG). Unlike other active suspension systems, this system is characterized by a reduced complexity. This reduced complexity is succeeded by the integration of the actuator inside the system. Hence, pumps,
hoses, filters or tanks can be omitted. Thereby a control of uncertainties is intended by the reduction of components fraught with uncertainty. In addition to this research focus the design of the HFD leads to new functions like active vibration control, stiffness control and the separation of hardware and function. The latter one means that it is possible to adapt the HFD to varying customer demands (such as sport or comfort set up) without any modifications of the hardware.
An Active Vibration Isolation Method Based on CMAC Network
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Zhang and Y. Liu and Y. Fu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 700-703,
April 2005
view abstract
Considering the nonlinearities in active vibration isolation system and the deficiencies of existing control methods, a novel method based on CMAC neural network is proposed. In the control structure, the CMAC network is adopted as controller, and the filtered-X concept is extended for use with the controller parameters update; a MLP network with taped line input is used to model the secondary path off line, thus parameters of the MLP network are combined with the error signal to jointly update the controller weights based on the stochastic gradient descent algorithm. Simulation results show the proposed method has good isolation performance for system with some nonlinearities.
An adaptive learning algorithm for controlling a two-degree-of-freedom serial ball-and-socket actuator
H. M. A. A. Al-Assadi and A. M. S. Hamouda et al.,
In Journal of Systems and Control Engineering,
2007,
volume 221,
pp. 1001-1006,
November 2007
view abstract
This article presents the development and implementation of an artificial neural network (ANN) for controlling a new two-degree-of-freedom (2DOF) serial ball-and-socket actuator. The ANN is a well-known algorithm for simulating the ability of the human brain to learn and predict sets of information. In this approach, ANN will learn the control parameters to obtain the angular displacement, angular velocity, and angular acceleration of the end-effector without any prior knowledge of the actuator. The ball-and-socket actuator has been proposed as an alternative actuator to the conventional one-degree-of freedom (1DOF) revolute actuator. The actuator was fabricated from a ball-and-socket joint powered by two electrohydraulic cylinders. Experimental control data had been collected manually and provided for ANN to learn in off-line mode. The training process was carried out to build control knowledge. Thus, the adaptive learning algorithm adopts any modification in the actuator mechanism and hydraulic power system through updating the control knowledge. The results of implementing the build control knowledge for on-line operation of the ball-and-socket actuator shows a fully compliant actuator end-effector to the desired dynamic behavior within the workspace.
AN ADVANCED GAP FLOW MODEL CONSIDERING PISTON MICRO MOTION AND ELASTOHYDRODYNAMIC EFFECT
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
C. Huang and M. Ivantysynova,
2006,
volume 1,
pp. 181-196,
Juni 2006
view abstract
The paper presents a new approach to consider the hydrodynamic pressure generation in the gap between piston and
cylinder due to the piston micro movement and elastic surface deformation of the piston and cylinder. Both effects are
essential to achieve full lubrication in the gap and can be used to reduce energy dissipation due to the gap flow. The
improved simulation model and its numerical implementation in CASPAR are introduced. The elastic surface
deformation is determined using constant influence matrix with fixed boundary. To eliminate the influence of the fixed
boundary condition on the surface deformation, a special coordinate system correction is introduced. The calculated
transient pressure field in the gap between piston and cylinder is compared with measured pressure field using a
special test rig.
An Agent-based framework for the Virtual Prototyping of Fluid Power Systems
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
G. Thimm and X. Wei and F. S. Cheong,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 49-57,
November 2003
view abstract
Interactions among the different standard virtual components during the virtual prototyping of
fluid power systems are modelled using an agent-based framework. The approach taken
represents each virtual hydraulic component by a domain agent. The agents are then gathered into
a multi-agent system, which models the hydraulic system as a whole. An additional agent, called
control agent, is used to co-ordinate the interactions in the multi-agent system. The feasibility of
the proposed agent-based framework is demonstrated by comparing the predicted pressure with
the measured pressure of a simple test rig. Simulation results demonstrate the potential of the
proposed framework for the assembly of a virtual fluid power system prototype using standard
virtual hydraulic components. A 3D tool facilitating the assembly and implicit construction of the
network of agents complements the system.
Analysis and Control of Multi-Mode Axial Flow Compression System Models
MingQing Xiao and Tamer Basar,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 393-401,
September 2000
view abstract
The paper studies the behavior of multi-mode systems of the Moore-Greitzer model. Its main result is the existence of a parameterized nonlinear state feedback controller which stabilizes the system to the right of the peak of the compressor characteristic. In this process, a rotating stall envelope surface is discovered, and it is shown that the controller design achieves the tasks of preventing the closed-loop system from entering either rotating stall or surge, and making the closed-loop pressure rise coefficient be able to approach its maximum. Numerical simulations of the open-loop and closed-loop models are presented to illustrate the analysis and the results.
Analysis and optimisation of the pressure reversing process of external gear pumps
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Petzold and W. Wustmann and S. Helduser and J. Weber,
2010,
pp. 235-247,
September 2010
view abstract
External gear pumps are widely used in Fluid Power applications. Despite their relatively simple design, their volumetric and hydro mechanical efficiency is rather high. On the other hand, the rates of pressure decrease during tooth engagement are very high, causing highly dynamic force alterations and increased pressure pulsations at the low- and high-pressure ports. During the enlarging of the displacement volumes the occurrence of cavitation on the low-pressure side is very likely. High noise emissions for this pump design are typical.
The paper presents investigations of the pressure changes in external gear pumps using Computational Fluid Dynamics (CFD). The CFD method can be used for the spatial resolution of fluid mechanical details without analytical assumptions to describe flow resistances. These benefits are outweighed by the time needed for the generation of dynamic flow grids. The commercial software ANSYS FLUENT is used to develop a 3D-CFD pump model. Comparisons are being made with experimental testing. Noise reduction potential is analysed by developing several variants of the pressure reversing geometry. As outstanding result of the investigation, the noise emission (acoustic power) of the pump could be reduced by 2 - 7 dB(A), whereas the pressure pulsations at the suction and delivery port of the pump were also decreased by up to 50 %. The investigations were funded by the German Research Foundation (Deutsche Forschungsgemeinschaft DFG).
Analysis of a Hydraulic Port, Plug, and Flow Through Fitting Subjected to Medium Pressure Shock Pulses
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
J. L. Bitant,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 371-385,
November 2003
view abstract
The purpose of this project was to analyze a hydraulic connection under the influence of medium pressure shock pulses. In hydraulic circuits, fittings with o-rings are used to connect hoses and tubing at junctions as well as to hydraulic components. The fittings use straight threads and are designed with an elastomeric seal, called an o-ring, which is used as the primary fluid sealing mechanism. The shape of the o-ring is toroidal, and to form an effective seal, the ring is compressed from 10-40% in a static application. From this author’s experience working in a test lab and in field service, many hydraulic leaks encountered in circuits are attributed to the failure of the o-ring. This project will examine the damage to fittings when subjected to cyclic test pressures between 21 and 55 MPa. The failure strength of the fitting’s thread and o-ring will be determined both experimentally as well as empirically. The major goal of this project is to determine the failure mechanism of a standard straight thread style fittings with o-rings used as the primary sealing mechanism. Results from calculations, modeling and testing concluded that o-rings do show effects from pressure pulses. Threads, ports and fittings showed no adverse effects in pressure ranges tested. Fatigue/impulse testing was performed on three sizes of fittings: SAE sizes –4, -6, and –8, and two different o-ring hardness values of 90 and 70 durometer. Impulse testing of the softer o-rings showed more damage and a permanent set. The harder (90 durometer) showed a set pattern but to a smaller degree. The movement of the o-ring under low pressure pulses predicted by finite element analysis were verified by using a high-speed video camera to view an assembly subjected to pressure pulses. The findings show the o-ring being forced up and conforming to the shape of the cavity when subjected to the pressure pulse.
Analysis of a Hydraulic Valve by Means of a Transient Multidimensional CFD Approach
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
D. Bottazzi and F. Franzoni and M. Milani and L. Montorsi,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 409-421,
März 2010
view abstract
In this paper the flow through a pressure compensator for a load – sensing system is studied by means of a CFD analysis under both steady state and transient operating conditions. For the transient simulations, the mesh motion is resolved on a time basis as a function of the external actuation system. In the analysis, an open source fluid-dynamics code is used and turbulence is accounted for in the modelling.
The analysis determines the trade off between the results accuracy and the computational efforts when comparing the steady state and transient approaches. In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated and confronted.
Analysis of a Pressure-Compensated Flow Control Valve
D. Wu and R. Burton and G. Schoenau and D. Bitner,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 203-211,
März 2007
view abstract
A pressure-compensated valve (PC valve) is a type of flow control device that is a combination of a control orifice and a compensator (often called a hydrostat). The compensator orifice modulates its opening to maintain a constant pressure drop across the control orifice. In other words, the PC valve is so designed that the flow rate through the valve is governed only by the opening of the control orifice and is independent of the total pressure drop across the valve. Because of the high nonlinearities associated with this type of valve, it is impossible, in practice, to design such a valve where the flow rate is completely unaffected by the pressure drop across the valve. In this paper, the effect of the nonlinearities on the performance of the PC valve is investigated. First, a generic nonlinear model of a PC valve is developed. Using this model, all possible operating conditions can be determined. Then a linearized model is developed and used to analyze the dynamic behavior of the PC valve. The model can then be used to evaluate and improve the design and operation of the valve for specific applications.
Analysis of a Tractor Rear Hitch Control System
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
A. Anthony and P. Casoli and A. Vacca,
2010,
volume 2,
pp. 589-602,
Juni 2010
view abstract
The paper describes the modelling, simulation and experimental verification of a tractor hydraulic circuit for control of the rear hitch. A numerical non linear and linearized model has been developed to detail the Hydraulic system pertaining to the subject valve. By use of the non linear model, all possible operating conditions can be determined. The simulation results have been verified with those obtained from experimental tests in steady-state conditions. A particular region of instability has been numerically identified at an operating condition. This region of instability is analysed at its operating point using the linearized model and the frequency response is studied using the bode plot to improve the functioning of the valve in this region. The objective was to improve the response of the system without altering the casting dimensions of the tractor rear hitch control valve.
Analysis of Capability for Manufacturing Pneumatic Cylinder Made from Polymers
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
P. Kot and E. Lisowski,
2010,
volume 2,
pp. 749-755,
Juni 2010
view abstract
In this paper, we present one of the possible approaches to a design process for pneumatic cylinder made from polymer
materials. Thanks to utilization of Moldflow Plastic Adviser software package, methodology for simulating plastic
material injection process was presented, with the consideration for all issues related with optimum selection of
injection points. Due to substantial differences in properties of the injected material depending on the fiber directivity,
the main focus was placed on simulations, providing at the output the probable distribution of glass fibers in the
designed molding. Based on the results generated by Moldflow system, the given components were divided into regions
with various glass fiber directivity with the use of CAD systems. The areas created this way were then imported into one
of the most popular CAE system i.e. Abaqus. In this particular application, with the use of available functionality,
proper dependencies and links were defined between individual regions. Based on the created geometry, a uniform
model a pneumatic cylinder was created, with the defined orthotropic material model. The created model was subjected
to a series of resistance simulations, the results of which were compiled in the final section of the paper, together with
the appropriate simulations carried out on an isotropic model.
Analysis of Electromagnetic Nonlinearities in Stage Control of a Stepper Motor and Spool Valve
Rich Burton and Jian Ruan and Paul Ukrainetz,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 405-412,
September 2003
view abstract
In digital valves, stepper motors are often used as the electro-to-mechanical interface. To sustain both high speed of response and good quantitative accuracy, a special algorithm has been designed to control the stepper motor to produce a continuous rotary displacement. Since in this algorithm the current to each coil is cyclic as the rotor tooth advances, several cycles can be used to achieve the desired angular displacement of the motor. This process can result in a reduction or "scaling down" of magnetic nonlinearities such as hysteresis and saturation. This cyclic algorithm has been defined as "stage control" because the algorithm need only be developed for one stage and then repeated when applied to subsequent stages. Critical to the development and understanding of the algorithm is an accurate model of the electromagnetic saturation and hysteresis which exist between the input current and output torque. In this paper, a special mathematical formulation is developed to simulate magnetic saturation and hysteresis which can be applied to a more generic situation. The mathematical formulation derived is one in which hysteresis and saturation parameters are established; an error rate of both saturation and hysteresis is defined from this. Since the error rates are easily determined experimentally or through manufacturers' specifications, the parameters can be found from these mathematical formulations. The parameters can then be used to predict the hysteresis and saturation characteristics. Special experiments are designed to obtain the input-output characteristics of a stepper motor/valve system under single and multistage control. The model follows the experimental results reasonably well and can be used with confidence to model any system with hysteresis and saturation. The model also predicts very well the effects of using stage control in reducing hysteresis and saturation in a practical valve.
Analysis of Flow Force in Valve with Notches on Spool
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Ryu and M. Ochiai and K. Ueno and F. Xin and J. Hong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 435-438,
April 2005
view abstract
To obtain satisfactory operation performance, the spool with notches is often used in the valve of construction machinery, such as excavator or crane. Since the structure of notches has large influence on the flow direction in the valve, the flow force on the spool is quite difficult to be predicted by the conventional calculation method. For example, the flow force in ordinary valve is considered to act in direction of closing the valve opening, but for the spool with notches, the flow force is possible to act in inverse direction in some conditions.
Authors used CFD to simulate the velocity, pressure distribution and flow force in the valve with notches. Experiment was also carried out in same condition of the CFD. Results show that the simulated flow force on spool fits quite well with that of experiment. And the inversion of flow force phenomenon can also be explained according to the distribution characteristics of pressure and velocity in valve obtained from CFD analysis results.
Analysis of Multiphase MultiComponents Internal Flow Fields
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
F. Franzoni and M. Milani and L. Montorsi,
2010,
volume 1,
pp. 177-190,
Juni 2010
view abstract
This paper is focused on the analysis of the internal flow-field in hydraulic component, carried on considering two
different approaches. On one hand an experimental methodology which enables the use of direct visualization
techniques to fluid power components has been adopted, on the other hand a properly tailored open source multidimensional
CFD code has been used to simulate hydraulic components subjected to high pressure gradient.
More in detail a test rig aimed at visualizing the internal flow field of transparent components reproducing the
geometrical shapes of actual interest for fluid power applications has been designed. In particular both a low pressure
power supply unit and different transparent prototypes hosting some concentrated and distributed pressure losses have
been designed. In order to force the fluid efflux to assume the fully turbulent condition also for the lowest hydraulic
power addressed to the prototypes the equivalent hydraulic diameter has been designed to be about 5 mm. Afterward,
the set-up methodology in using the fast image processing is considered, and some of the results obtained using a
progressive, mid resolution, high frame rate and monochrome digital camera are shown. Among others, the internal
flow evolution is studied to highlight the digital technique capability both to capture qualitatively the fluid efflux
characteristics, and to support the quantitative definition of their average values. Finally, for some relevant cases, the
digital information are compared with the internal flow-field as depicted by a multi-dimensional CFD code, to evidence
both similarities and differences.
Moreover the incompressible flow through a closed center directional control valve for load –sensing application is
studied by means of a multidimensional open source fluid-dynamics code. The effects of turbulence are accounted for in
the analysis by means of a two equation approach.
Both direct and inverse flows through the metering section of the control valve are investigated, and the differences in
terms of fluid – dynamics behavior are addressed. In particular, the comparison between the results obtained by a
steady state approach and a full transient approach in the numerical analysis are compared in terms of discharge
coefficient, recirculating regions, flow acceleration angle and pressure and velocity fields
Analysis of Robust Electrohydraulic Force Control
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
C. P.G. Lamming and A. R. Plummer and A. J. Hillis,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 355-366,
März 2010
view abstract
Force control is widely used, for example to simulate in-service loads in structural and component test rigs. Simulating downforce on a F1 racing car is an example. Electrohydraulic force control systems, in common use for high performance structural tests, suffer from the effects of specimen motion, which must be compensated for using velocity feedforward. The necessary inverse model of the valve and actuator will be an approximation to the true, non-linear system and so model error results. This paper provides an analysis on the effect of link stiffness on the system stability, given an error in the inverse model. It is found that reduced link stiffness can improve stability margins significantly but that the system will be intolerant to excessive feedforward gain, whatever link stiffness is chosen.
Analysis of spool rotation and hydraulic lock in directional control valves
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
D. Borchers and E. Englberth,
2008,
pp. 144-151,
September 2008
view abstract
Two undesired phenomena occur in some hydraulic directional control valves:
A rotation of the spool inside the valve and the so called „hydraulic lock”.
The rotation is induced by a tangential net force which may be the result of an asymmetric
incoming flow. The hydraulic lock is the result of a radial net force, acting on the spool.
Based on this force a high friction occurs in the metal-metal contact between spool and
housing. Reasons for this force are unbalanced pressure fields around the spool, or flow
forces.
• The disadvantage of the rotation is the friction between the rotating spool and
stationary parts of the valve. This may cause an abrasion of the tappet at the end face
of the spool.
• The disadvantage of the hydraulic lock is a less sensitive shifting of the spool, which
makes proper proportional control impossible and if switching valves are used, a
higher actuating force is required.
One of these undesired phenomena can be suppressed by the other. They cannot appear at the
same time.
This paper presents proposals to suppress the spool rotation. The investigations are realized
by CFD simulated design modifications of the housing. The solutions are based on a
symmetrically piped flow to the spool for equalizing the tangential flow components.
The problem of most of these solutions is an increase of the radial flow force which may
cause the hydraulic lock. In not modified housings the hydraulic lock has been analyzed for
special flow and spool combinations on a test bench.
Analysis of the Dynamics of a Proportional Valve Operated by an Electronic Controller
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
D. Cristofori and A. Vacca,
2010,
volume 1,
pp. 199-214,
Juni 2010
view abstract
The purpose of this work is to describe a numerical methodology for the analysis of the dynamic behavior of a
proportional relief valve operated by an electronic controller. The main purpose of the research is to create a
predictive tool able to correlate the performance of the valve to the logic implemented in the electronic controller. The
analysis is based both on a numerical and experimental approach.
A numerical model for the proportional valve and for the electronic controller has been implemented, according to the
lumped parameter approach, using the AMESim® simulation platform. Regarding the proportional valve, a nonlinear
model has been developed. The model is basically given by three sub-models: the first one performs the evaluation of
the fluid flow characteristics; the second one evaluates the motion of the moving element; the third one models the
electrical transient and the forces exerted by the electromagnetic actuator. In particular, the electromagnetic sub-model
is based on the results of a FEA model of the proportional electromagnet. Regarding the electronic controller, its
control logic has been implemented in order to evaluate the PWM output voltage as the results of two PI controllers:
the pressure loop (that relates the set-point pressure and the feedback pressure) and the current loop (that relates the
set-point current and the feedback current).
To validate the model and analyze the interactions between the two models (valve and controller), a proper hydraulic
test rig was set up. The test apparatus allows detecting the dynamics of the controlled valve, isolating its dynamics from
the rest of the hydraulic circuit of the test rig. The experiments performed in this work allow the control of the
proportional valve through a PI closed loop in order to maintain a constant pressure in a section of the hydraulic test rig in presence of an external disturbance.
The apparatus used to perform the test was reproduced in the AMESim® simulation environment and the resulting
model were connected to the proportional valve and the electronic controller models. In the final part of the paper,
numerical results are compared with experimental ones, highlighting the potentials of the modeling approach
developed in this research.
Analysis of the Suction Performance of Axial Piston Pumps by Means of Computational Fluid Dynamics (CFD)
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
N. Bügener and S. Helduser,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 641-654,
März 2010
view abstract
The paper deals with measures to improve the suction behaviour of hydraulic pumps. With the Helmholtz resonator and the revolution oriented suction line two possibilities are analysed. The resonator constitutes a possibility to reduce pulsation and so the inlet pressure losses. Both experimental and numerical analyses are done. The commercial software FLUENT is used for Computational Fluid Dynamics – CFD. The revolution oriented suction line is also investigated with the help of that tool. In the article it is shown that the cavitation intensity can be reduced at the beginning of the suction stroke by using the presented measure.
Analysis on Dynamic Characteristic of a High-pressure Water Generator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Li and F. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 532-536,
April 2005
view abstract
This paper establishes and analyzes a dynamic model in power bond graph of a high-pressure water generator. The power train is visualized, in which the power is transmitted, transferred, stored and consumed. The structure characteristics of the system and various factors are represented accurately. Having interosculated impinging jet's parameters to influence dynamic characteristic of the system, The status equation group is established, which is logically contacted to mathematic model of status variations based on modem control theory. By simulation, dynamic response curves of operating pressure and generator plunger velocity are obtained under various conditions. All fruits here give out the theoretical ground and design guide for the exploiture and application of the high-pressure fluid generator.
Analysis on Dynamic Characteristic of a High-pressure Water Generator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Li and F. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 532-536,
April 2005
view abstract
This paper establishes and analyzes a dynamic model in power bond graph of a high-pressure water generator. The power train is visualized, in which the power is transmitted, transferred, stored and consumed. The structure characteristics of the system and various factors are represented accurately. Having interosculated impinging jet's parameters to influence dynamic characteristic of the system, The status equation group is established, which is logically contacted to mathematic model of status variations based on modem control theory. By simulation, dynamic response curves of operating pressure and generator plunger velocity are obtained under various conditions. All fruits here give out the theoretical ground and design guide for the exploiture and application of the high-pressure fluid generator.
Analysis, simulation and experiments on a proportional flow control valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Roccatello,
2004,
pp. 481-488,
Juni 2004
view abstract
This study is focused on the formulation and experimental validation of the mathematical model of a
servo-proportional valve with closed loop spool position control. The model, based on a lumped
parameters approach, makes use of geometric measurements on the real hardware to proceed to the
evaluation of valve’s hydraulic characteristics (e.g flow areas, variable volume chambers etc); model
validation rests on experimental studies of flow and solenoid forces that bear evidence of hysteretic
phenomena.
Analytical Coupled Modeling and Model Validation of Hydraulic On/Off Valves
John Mahrenholz and John Lumkes, Jr.,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
Januar 2010
view abstract
The goal of this paper is to describe a method for modeling high speed on/off valves. This model focuses on the nonlinearities of the electromagnetic, fluidic, and mechanical domains, specifically within solenoid driven poppet style valves. By including these nonlinearities, the model accurately predicts valve transition time for different driving voltages and valve strokes. The model also predicts fluid transients such as pressure ripple. Unique attributes of the model are the inclusion of the effect of eddy currents and fringing while still being fully coupled with the fluid and mechanical domains. A prototype was constructed and used to experimentally validate the model. By developing accurate lumped parameter models, valve dynamics can be applied to hydraulic systems to accurately capture their dynamics.
Analytical Solution of Filling and Exhausting Process in a Pneumatic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J. Yingzi and Y. Qingjun and W. Zuwen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 320-324,
April 2005
view abstract
The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that: 1) Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and 2) the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and 3) the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and had nothing to do with the length of the tube.
Analytic Formulas for Hydrogenerator Efficiency (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
G. Koreisová and J. Koreis,
2008,
pp. 338-345,
September 2008
view abstract
The contribution describes the possible way of analytical expression of the hydrogenerator
efficiency curves. It is based on the knowledge of the efficiency curves, obtained
through measurement. The efficiency curves can be found in catalogue documentation from
producers of hydro-static convertors. Catalogue documentation is usually very concise. For
hydro-generators with variable displacement, the efficiency curves are stated only for the
maximum displacement and constant pressure of two selected levels, most frequently for the
maximum pressure and one constant reduced pressure. As examples of regulation hydrogenerators
for closed hydraulic circuits, regulation hydro-generators fy Sauer – Danfoss
Serie 90 were selected. In Fig 1 and 2, the efficiency curves from measurement evaluation are
shown, obtained from the information source [3]. To determine the efficiency curves in other work modes, it is convenient to know their
analytical expression. The efficiency is a function of three input values of a hydro-generator
displacement, revolutions and pressure. All sizes of hydro-generators of one type have the
same maximum work pressure. In catalogue documentation from producers, the revolutions
of hydro-generators are specified in diagrams in a dimensionless form. With constant
displacement, the dependence of the efficiency on dimensionless revolutions and pressure is
the same for all sizes of hydro-generator of a specific type. To keep this quality, dimensionless
content will be used for analytical relations as well. The goal of the contribution is to find
analytical expression of the dependence of the efficiency on all three input values of hydrogenerators.
AN ANALYSIS OF A HYDRAULIC CYLINDER SEALING BY THE USE OF FINITE ELEMENT METHOD
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Hawryluk and E. Lisowski,
2008,
pp. 472-478,
Juli 2008
view abstract
Hydraulic cylinders are one of the basic components in the drives of heavy duty machines. In machines which are
equipped with hydraulic drive, usually occurs several or even a dozen or so cylinders which are working in a different
systems. Due to this fact, research and development works which are carried out on solutions regarding sealing of the
cylinders, are focused on elimination of oil leakage into the environment, reduction of friction and extension of an
operation time. The paper presents a nonlinear FEM analysis of various solutions of elastomeric seals used in
hydraulic cylinders of heavy duty machines. To conduct FEM analyses ANSYS system has been used. Achieved
information such stresses, contact pressure plots for various types of seals, allows to predict and improve operational
sealing capabilities and can be also useful on works regarding wearing processes. The geometry of the FEM model was
parametrized, so that to be easily modified or used in an optimization process. Performed models and achieved results
may be used in further, more developed analyses covering instroke and outstroke of piston rod, different thermal
conditions and also the use of FSI method (Fluid Solid Interaction).
AN ANALYTICAL AND EXPERIMENTAL STUDY OF CHAOTIC OSCILLATION IN A PNEUMATIC CYLINDER
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
T. Kosaki and M. Sano,
2000,
pp. 303-310,
September 2000
view abstract
Seal friction of pneumatic cylinders possesses uncertain properties due to the interference of various factors,
and it causes random oscillation or stick-slip when the piston is driven at extremely low speed. A deeper understanding
of the friction force is required for avoiding this oscillation phenomenon, which results in a deterioration
of performance. This paper focuses on analyzing the oscillation phenomenon appearing in time responses of
the driving velocity of the piston. In order to investigate aspects of velocity responses in a meter-in and meterout
circuit, we first use an analytical approach with a mathematical model including the friction force under
some assumptions. An experimental study is then performed, showing the relationship between an effective sectional
area of control valves and oscillatory behavior. It also shows by using some chaos indices, such as
Lyapunov exponents, that the behavior of piston velocity turns chaotic under certain conditions in actual situations.
In addition, the effects of changes in both supply pressure and load are examined. Based on both theoretical
and experimental results, we confirm that the oscillation is caused by the nonlinear friction force.
AN APPLICATION OF DELEGATED COMPUTATION: THE CORPORATE MULTI AGENTS INFORMATION RETRIEVAL SYSTEM OF CHINA HYDRAULICS PNEUMATICS AND SEALS WEB SITE (CHINAHPS).
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
M. Sangare and C. Yang and Y. Chen,
2000,
pp. 485-492,
September 2000
view abstract
What does a member of our corporation search for on the Web? Technical data, product characteristics and
recommendations of the manufacturer of a component or device he wants to use in machine building or maintenance
task. These types of data are not stored in HTML pages only, but in text files and databases too. On the
other hand, the traditional binary search is not adapted to industrial corporations information need. In manufacturers’
catalogue, it is rare to find a product that matches exactly the mathematical model of a project draft.
It is often necessary to choose one with the closer characteristics to those of the model. The HPSBot is a multi
agents search system, a project initiated by the State Key Laboratory of Fluid Power (SKLoFP) that aims to
organize data coming from multiple heterogeneous sources in easily accessible structures. All the information
sources are selected by the system from fluid power companies or in the whole Internet on a domain context
basis. In this paper we describe the structure of the system. We emphasize on the harvesting agent’s algorithm to
show and efficient way of domain based multi languages information sources selection.
An Automatic Shut-off Valve for Hydraulic Accumulators
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
J. Song and S. Zhou,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 55-57,
November 1996
view abstract
This paper introduces an automatic shut-off valve device used in conjunction with a hydraulic accumulator that compensates for leakage in hydraulic accumulator circuits. This device shuts off automatically to prevent the pressurized oil inside the accumulator from draining out whenever the pressure of the circuit drops to zero. Therefore, it saves the time and energy of recharging the accumulators.
An electrohydraulic vibration exciter using a two-dimensional valve
J. Ruan and R. Burton,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2009,
volume 223,
pp. 135-147,
März 2009
view abstract
A scheme for an electrohydraulic vibrator excited by a two-dimensional valve is proposed, which significantly extends the frequency range compared to that of vibrators
excited by conventional servo valves. In the two-dimensional valve, the rotary motion of the spool coordinates the relative motion of the grooves on the spools area with respect to the windows on the sleeve which in turn, alternates the oil flowrate into and out of the chambers of
the hydraulic cylinder (motor) and subsequently excites the piston (rotor) to vibrate. The linear motion of the two-dimensional valve spool is used to vary the peak flowrate and thus the amplitude of the output vibration. The frequency of the vibration excited by the two-dimensional
valve is related to the rotary speed of the spool and the number of the grooves on the spool area (windows on the sleeve). This configuration extends the frequency of the
hydraulic vibrator by increasing the number of the grooves on the spool area (windows on the sleeve) and the rotary speed of the spool which are in the perfect lubrication of oil.
A model of the two-dimensional vibrator is developed and compared to its experimental counterpart. The vibration excited by the two-dimensional valve is influenced by pressure
saturation, the elastic force, and the hydraulic resonance. There is a critical valve linear opening, beyond which the output force (torque) reaches a saturation value in both a positive and negative sense. Both simulation and experimental results show that at lower frequencies the ascent and descent slopes of the output force show some inconsistency which becomes more significant above the critical valve linear opening but drops off with a reduction in the valve linear opening. In a higher frequency range, the vibration excited by the two-dimensional valve is mainly influenced by hydraulic resonance. As the input frequency approaches the
hydraulic resonant frequency, the output excited vibration essentially becomes the hydraulic resonance. Therefore, the effective frequency range of the hydraulic vibration is not only decided by the frequency bandwidth of the two-dimensional valve, but is influenced by the hydraulic resonance. Nevertheless, the study does provide an access to the high-frequency excitation of the hydraulic vibration.
An electropneumatic control and actuation system for the vanes of the variable geometry turbine of a turbocharged diesel engine
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
A. Almondo and G. Jacazio,
2007,
pp. 269-280,
September 2007
view abstract
The study of an electropneumatic control and actuation system is herein presented, that performs a closed loop control of the boost pressure of a turbocharged diesel engine using electrical signalling and pneumatic actuation. The pneumatic actuator force is controlled by modulating the vacuum pressure generated by a camshaft driven pump. A proportional solenoid valve accepts the control signals from an electronic controller, thereby varying the pressure on one side of a spring loaded pneumatic actuator; the resulting force balance determines the actuator piston position, which in turn drives the turbine vanes. The modulation of the turbine vanes permits to control the turbocharger power, thus varying the engine boost pressure. This is measured by a sensor, and a pressure control loop is closed with a law using a combination of PID and feed-forward control.
The development of both linear and non Linear models describing the interaction between engine, turbocharger and control strategy can be instrumental in assessing the system performance both in steady-state and transient conditions, determining the optimal control, establishing the maximum acceptable tolerances of the system components to meet the pressure control accuracy, and in evaluating the merits of adding an internal position control loop for the actuator position. Interesting applications of this model based approach have been proposed in literature by Rask and Sellnau [1], Moskwa and Hedrick [2] and Filipi et al. [3].
The paper first outlines the boost pressure control system architecture and characteristics, then it describes the system model and presents the most significant results and lessons learned during the control system study by means of linear and non linear models.
AN EMPIRICAL DISCHARGE COEFFICIENT MODEL FOR ORIFICE FLOW
D. Wu and R. Burton and G. Schoenau,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 13-18,
Dezember 2002
view abstract
In fluid power systems, flow control is mainly achieved by throttling the flow across valve orifices. Lumped parameter
models are generally used to model the flow in these systems. The basic orifice flow equation, derived from
Bernoulli’s equation of flow, is proportional to the orifice sectional area and the square root of the pressure drop and
is used to model the orifice coefficient of proportionality. The discharge coefficient, Cd, is often modeled as being
constant in value, independent of Reynolds number.
However, for very small orifice openings, Cd varies significantly and can result in substantial error if assumed
constant. In this situation, modelers usually revert to graphs or look–up tables to determine Cd. This paper provides a
closed form model for Cd as a function of the Reynolds number which can be applied to different types of orifices.
Based on this model, a technique to evaluate flow given an orifice area and pressure drop without having to use iteration
is introduced.
AN ENERGETIC COMPARISON BETWEEN VALVELESS AND VALVE CONTROLLED ACTIVE VIBRATION DAMPING FOR OFF-ROAD VEHICLES
Proc. JFPS2005, Tsukuba, Japan
B. Eggers, R. Rahmfeld, M. Ivantysynova,
2005,
view abstract
This paper presents a comparison of the energetic consumption of a valveless and a valve controlled active oscillation damping system for off-road machinery. Today only passive oscillation damping systems are subject to off-road machine series production.
These systems offer the advantage of no additional primary energy use for damping. However, the disadvantages are the high costs and no adaptation possibility to the operating parameters. The recent developments where valve controlled linear actuators have been used for active damping had to face several problems with too low dynamics of today’s implemented control valves and the high additional energy need. These disadvantages can be avoided by using valveless linear actuators for working functions and for active damping. In fact, throttling losses are omitted and, energy recovery is possible. It will be shown based on measurement and simulation results that a suitable damping quality can be achieved with valveless linear actuators. Therefore, some aspects of the controller design will be given. Hereby, a simple acceleration sensor and standard control hardware are used. The main part will describe the energetic modelling, whereby especially precise pump loss models have been developed. The energy consumption of both systems performing active damping is compared in detail.
KEYWORDS
Mobile hydraulics, Displacement control, Valveless, Valve control, Active Oscillation Damping, Energy Saving, Linear Actuators
An Energetic Control Methodology for Exploiting the Passive Dynamics of Pneumatically Actuated Hopping
Yong Zhu and Eric J. Barth,
In Journal of Dynamic Systems, Measurement, and Control,
2008,
volume 130,
Juli 2008
view abstract
This paper presents an energetically derived control methodology to specify and regulate the oscillatory motion of a pneumatic hopping robot. An ideal lossless pneumatic actuation system with an inertia is shown to represent an oscillator with a stiffness, and hence frequency, related to the equilibrium pressures in the actuator. Following from an analysis of the conservative energy storage elements in the system, a control methodology is derived to sustain a specified frequency of oscillation in the presence of energy dissipation. The basic control strategy is to control the pressure in the upper chamber of the pneumatic cylinder to specify the contact time of the piston, while controlling the total conservative energy stored in the system to specify the flight time and corresponding flight height of the cylinder. The control strategy takes advantage of the natural passive dynamics of the upper chamber to provide much of the required actuation forces and natural stiffness, while the remaining forces needed to overcome the energy dissipation present in a nonideal system with losses are provided by a nonlinear control law for the charging and discharging of the lower chamber of the cylinder. Efficient hopping motion, relative to a traditional nonconservative actuator, is achieved by allowing the energy storing capability of a pneumatic actuator to store and return energy to the system at a controlled specifiable frequency. The control methodology is demonstrated through simulation and experimental results to provide accurate and repeatable hopping motion for pneumatically actuated robots in the presence of dissipative forces.
A Neuro-Fuzzy Control of an Electro-Hydraulic Fin Position Servo System
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
S. Y. Lee and Y. J. Park and H. S. Cho,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 101-106,
November 1996
view abstract
The electro-hydraulic servo systems have been frequently used in the fin position servo system of a missile because of their
high power and good positioning capabilities. This paper presents a neuro-fuzzy control scheme for an electro-hydraulic fin position servo system. In this paper, we have explained
a fuzzy control scheme which has multi-dimensional and
asymmetrical membership functions, and we have designed a neuro-fuzzy controller which include parameters of the fuzzy logic controller. The effectiveness of this control scheme is verified by comparison with the conventional control algorithm through a series of simulation studies.
A new acceleration feedback design method for electrohydraulic motion control systems
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
A. R. Plummer,
2006,
pp. 277-290,
September 2006
view abstract
For at least four decades, the use of acceleration feedback has been known to be an effective tool for improving the transient response of electrohydraulic servosystems with inertia-dominant loads. However, in practice, the choice of acceleration feedback gain is still typically a matter of trial and error. Analyses which are available do not account for the valve dynamics in a sufficiently realistic (yet simple) way to be of use in many practical situations. In this paper a design method is proposed, and applied to a validated simulation of a seismic table. It is suggested that, in this case, differential pressure feedback (although
nominally equivalent to acceleration feedback) is superior, as the sensitivity to mass variation is reduced.
A new approach for modelling and identification of the pneumatic artificial muscle manipulator based on recurrent neural networks
K. K. Ahn and H. P. H. Anhn,
In Journal of Systems and Control Engineering,
2007,
volume 221,
pp. 1101-1121,
Dezember 2007
view abstract
Pneumatic artificial muscles (PAMs) are widely used in the various fields of medical robots and other industrial applications. As a powerful tool of intelligent control, neural networks nowadays are applied effectively to model, identify, and control highly non-linear systems, including the PAM manipulator. In the current paper a prototype PAM manipulator is modelled through recurrent neural networks (NN) modelling and identification based on experimental input-output training data. The proposed incremental back-propagation (INCBP) algorithm, which yields faster convergence than a conventional back-propagation (BP) algorithm, is applied to train the neural networks. The realization of the INCBP algorithm is given. An evaluation is carried out for different non-linear NN auto-regressive with exogenous input (NNARX) models of a PAM manipulator, using recurrent NN with various input nodes as well as various hidden layer nodes. For the first time, the non-linear NNARX model scheme of the prototype PAM manipulator has been investigated. The results show that the non-linear NNARX model trained by INCBP yields better performance and higher accuracy than the traditional linear ARX model. These results can be applied in modelling, identifying, and controlling not only the PAM manipulator, but also other highly non-linear systems.
A New Electrostatic Oil Filter Utilizing AC and DC Electric Fields
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Yanada and Y. Yoshida and T. Imaizumi and F. Ohkubo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 41-44,
April 2005
view abstract
In order to lengthen the lives of hydraulic fluids and lubricating oils and to decrease the failures of machines including hydraulic systems, it is essential to remove submicrometer-sized contaminants such as the oxidation products of oil from those liquids. An electrostatic oil filter (ES filter) can remove such minute contaminants, which cannot be removed by usual mechanical filters, from liquids. However, the size of conventional ES filters is rather large compared to its filtration speed; in addition, the conventional ES filters use disposable filter elements that will become waste after a certain period of time in use.
Yanada et.al have proposed a new type of ES filter that utilizes both AC and DC electric fields and of which filter elements are made of stainless steel mesh for semipermanent use. However, the usefulness of the ES filter has not fully been verified yet. In this investigation, two types of the ES filter utilizing AC and DC electric fields are made on an experimental basis. The two ES filters are cylindrical in shape and consist of a coagulating part, in which an AC electric field is applied to make minute contaminant particles become coagulated, and of a capturing part, in which the particles are captured by the action of a DC electric field. The coagulating and capturing parts are arranged on the outer part and in the middle part of the cylinder, respectively. The sole difference in the two types of ES filter is in the flow direction in the coagulating part: one is in the axial direction and another in the circumferential direction; the difference leads to different magnitudes of the velocity gradient in the passage of the coagulating part.
It is shown that the filtration speed is relatively largely increased by utilizing both the AC and DC electric fields compared to the case where only the DC electric field is applied, and the usefulness of the ES film proposed is demonstrated. Comparison between the performance of the two types of ES filter shows that the magnitude of the velocity gradient in the passage of the coagulating part strongly affects the filter performance.
A NEW EXPERIMENTAL ALGORITHM FOR THE EVALUATION OF THE TRUE SONIC CONDUCTANCE OF PNEUMATIC COMPONENTS USING THE CHARACTERISTIC UNLOADING TIME
S. de las Heras,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 17-24,
März 2001
view abstract
In this paper an alternative method for obtaining the sonic conductance of pneumatic valves, C, is presented. The
method uses the characteristic unloading time defined in a transitory discharge process and supposes an experimental
cost lower than the ISO 6358 procedure. With this method the test rig needed is not so large and a precise measure of
the variables involved in the discharge, pressure, mean temperature or specific volume, is not required either. Furthermore, the author has found out experimentally that C depends on the geometric factor L/D of the chamber that impulses the mass flow rate and not only on the effective section A of the valve element. The sonic conductance obtained by the characteristic unloading time method is smaller than the one obtained by the ISO 6358, and finally explains some experimental points. Firstly, the effective mass flow through some valves is significantly inferior to the one expected
when considering the C ISO estimation. And secondly, it looks like if the valve would conduce a different mass flow
depending on the system to which it is connected.
A NEW FLUID - STRUCTURE INTERACTION MODEL FOR THE SLIPPER – SWASH PLATE INTERFACE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Pelosi and M. Ivantysynova,
2008,
pp. 219-236,
Juli 2008
view abstract
The objective of this research is to develop a fully coupled fluid-structure simulation tool to investigate the impact of
local surface deformation on the gap height of sealing and bearing slipper gap in axial piston machines. The gap height
represents one of the most important design parameters for axial piston machines and its determination is a difficult
problem when considering fluid-structure interaction, involving a complex coupling between fluid forces and external
forces exerted on moving parts. Local surface deformation due to the high pressure load associated with these
machines takes place, affecting the gap height value as well. A precise finite element model of the slipper has been
developed and implemented inside the simulation tool CASPAR (Calculation of swash plate type axial piston pump and
motor). The slipper finite element model, based on eight node solid elements, will allow the study of
elastohydrodynamic effects on slipper surface, thus the calculation of the local surface elastic deformation due to the
pressure field within the gap. The results of this research will improve the knowledge on fluid structure interaction in
axial piston machines and will outline new methodologies for the design of slipper/swash plate bearing and sealing
gaps.
A New Generation, High Performance, Water Soluble, Polyalkylene Glycols and their Use in Hydraulic Equipment for Environmentally Sensitive Areas
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
K. Kovanda, M. Greaves, R. Schulze,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 89-102,
März 2010
view abstract
Natural and synthetic ester based lubricants have traditionally been the preferred choice for use in equipment where the risk of spills and leaks to the environment is a concern. In the class of “environmentally-friendly” hydraulic fluids the better alternative choice is the use of polyalkylene glycols (PAG) which can offer excellent equipment reliability and long life for mobile and stationary equipment used in extreme climates and conditions and have very favorable environmental profiles.
This paper will discuss the chemical design of PAG’s as a very versatile process and by carefully controlling the weight ratio and degree of polymerization of ethylene oxide and propylene oxide, a wide variety of polymers can be designed offering different functional performance. PAG’s can be chemically engineered to be fully water-soluble. This allows PAG’s to be used to formulate a lubricant that does not form a sheen per 40 CFR 435 NA. This is a key benefit in applications where fluids can leak into waterways, lakes or open fields as they are non-toxic and readily bio-degradable. Their non-sheening performance differentiates them from hydrocarbon oils and ester lubricants. Several benefits of PAG’s are highlighted including their excellent hydrolytic stability, film forming properties and their ability to minimize deposit build-up in equipment.
Successful field experiences in using such PAG lubricants in tunnel boring equipment and in mobile and marine equipment used on and off-shore are especially highlighted.
A New Generation of Pneumatic Flexible Actuators Based on Innovative Textile Products
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
G. Belforte and G. Eula and A. Ivanov and R. Grassi and S. Appendino,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 155-166,
März 2010
view abstract
This work presents a set of results obtained by investigating the possibility of constructing textile based pneumatic muscles by applying some of the most widespread bonding techniques. The work refers to a set of experimental feasibility tests that are in progress in the attempt of joining airtight fabrics with the same technologies in use for conventional waterproof or windproof junctions. In particular, laser welding, ultrasonic welding and adhesive bonding have been investigated. The paper concentrates on presenting the results obtained by applying continuous ultrasonic welding techniques to a couple of innovative multilayered fabrics which properties are suitable for the realization of artificial muscles.
A New Mechanism of Coolant Spray for Improving Strip Shape in Hot Rolling Mills
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Gao and X. Kong and Y. Hou and Q. Zhang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 252-256,
April 2005
view abstract
Based on analyzing the cooling mechanisms and methods which are widely used in modern hot rolling mills, a new type of continuous wide adjustable cooling mechanism is presented to improve the localized defects in the strip such as middle ridges, edge ridges. Not similar with traditional cooling sprays, the new cooling set provides a 'water screen' along the entire strip width instead of 'water streams' impacting on the meta1 surface and both the width and height of screen are adjustable by hydraulic cylinders for adaptive to strip width changes. The numerical model of heat transfer within the contact area is developed and various issues associated with effective use of cooling sprays to control shape are investigated. The experiment results show the method developed in this paper is feasibility and can be used in real industry application for improving strip shape control even there are rapid changes of rolling rhythm and strip width.
A new method for power steering hose assembly design and acoustic optimisation by means of time domain hydraulic line simulation models
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
H. Baum and M. Hofmann,
2007,
pp. 367-382,
September 2007
view abstract
A known source of noise within the interior of a vehicle is from the hydraulically-assisted power steering system. Up to now the design and optimization of power steering hoses is mainly done by costly hardware tests. The method of power steering hose design and optimization presented in this paper implements a flexible wall model into distributed parameter time domain simulation models. During simulation significant design parameters such as tuner cable length and position or restriction dimension and position are automatically modified by a parameter variation algorithms.
This way the new method effectively evaluating various design alternatives at earlier stages in the development process and represents a key step in implementing innovative simulation methods that further increase the quality and performance of NVH development process.
A NEW METHOD FOR TESTING THE FOAMING REACTION OF LUBRICANTS AND HYDRAULIC OILS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
J. Leichnitz,
2006,
volume 1,
pp. 161-170,
Juni 2006
view abstract
Free air in oil can have a negative effect on the performance of hydraulic or lubrication systems. Apart from
constructional preventive methods to reduce oil foaming there is the possibility of introducing foam inhibiting additives.
But even with foam inhibitors it is difficult to predict the foaming behavior of oil. With the aid of a simple test rig it is
shown how different oils react when free air is in the system. Furthermore several boundary conditions to characterize
an oil in a proper way are presented. When this backgrounds are taken into account, empirical test are useful to
analyze the foaming and air release properties of oil in order to facilitate the selection of appropriate foam inhibitors.
For the professional testing of lubricants a new process has been developed at the Institute of Agricultural Machinery
and Fluid Power (ILF) at the Technical University of Brunswick in cooperation with the Volkswagen AG Wolfsburg.
This new testing process, which is distinguished not only by its close adherence to practical usage, but also by its
extensive utilisation of automation, will be explained.
A new pneumatic vanes motor
J. Naranjo and E. Kussul and G. Ascanio,
In Mechatronics,
2010,
volume 20,
pp. 424-427,
April 2010
view abstract
A small pneumatic motor has been developed as an alternative to electric motors for machining processes at small dimensions with potential use in micromachines and microfactories. The novelty of the present design is based mainly on the use of vanes made of self-lubricating material and pressurized air supplied through a series of holes of a rotating hollow shaft for keeping the vanes in contact with the inner wall of the stator avoiding the use of springs. The pneumatic prototype was extensively characterized in terms of the locked rotor torque, brake power, no-load speed and the volumetric efficiency.
A New Simulation Platform for Mechanical and Hydraulic Hybrid System --- Especially for Hydraulic Manipulators
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
W. Sun and M. Linjama and T. Virvalo,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 271-280,
November 2003
view abstract
In this paper, a set of models based on SimMechanics and Simulink in Matlab are introduced
as a new control system simulation platform for hydraulic booms or manipulators. Using the
new features of SimMechanics and Simulink, a mechanical structure can be "assembled" in
the Simulink environment. Even more, the operation and movements can be animated on the
screen during the simulation time. Actuators and sensors can be added at user's pleasure, so
that any information of the system can be obtained easily. Simulink models of hydraulics are
available in this platform, such as cylinders, valves, and orifice. The parameters can be set to
fit the real products for each of them. A hydraulic crane is shown as example model in this
paper. Using this platform, system/component designers can setup their models much faster;
may get simulation result with much higher accuracy and better view of visualized simulation.
A New Type of Continuously Variable Displacement Mechanism Used for Camshaft Connecting-rod Low Speed High Torque Hydraulic Motors
ISBN: 01-0125-06,
Li Yong and Shi Guanglin and Chen Zhaoneng,
In Journal of Shanghai Jiaotong University (Science),
2007,
volume E-12,
pp. 125-130,
Februar 2007
view abstract
On the base of traditional camshaft connecting-rod low speed high torque (LSHT) hydraulic motor with dual displacement, a continuously variable displacement mechanism, which is composed of a hydraulic control valve with mechanical-positional feedback to camshaft, is designed for changing the displacement of the traditional LSHT hydraulic motor continuously. So the cam ring on camshaft of the traditional LSHT hydraulic motor can stop at any position between minimum and maximum eccentricity, according to an input fluid pressure signal. And it can also stay anywhere stably through self-adjusting. The new type of continuously variable displacement mechanism is simple and easy to be made. Besides, it can work stabilized when load impact or oil leakage exists.
Firstly, the structure and principle of the continuously variable displacement mechanism is introduced in this paper. Secondly, the mathematic model of the continuously variable displacement mechanism is set up and its static and dynamic characteristics are analyzed with the help of computer simulation.
A New Type of Digital Electrohydraulic Speed Governor for Hydraulic Turbines
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
N. Vasiliu and C. Calinoiu and D. Vasiliu,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 625-628,
November 2003
view abstract
The paper contains a report on a long series of theoretical and experimental activities aiming
to create a new type of electrohydraulic digital speed governor for hydraulic turbines.
Computational methods, control software, design problems, and experimental validation are
shortly presented.
A New Versatile Tube Bending Machine with Hydraulic Parallel Kinematics
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
H. Goto and Y. Tanaka,
2010,
volume 2,
pp. 529-536,
Juni 2010
view abstract
This research presents a new versatile bending machine and its practical applications. The proposed machine uses a
new method. When tubes are fed into the fixed and mobile dies, they are bent by shifting the relative position of the
mobile die .The bending radius is controlled by the relative distance and orientation between the mobile die and the
tube. The bending angle is controlled by the length of the fed tube. This forming process has a big advantage. A change
of the expected bending shape will need no change in the tooling system but only a new definition of the motion of the
active die and the length of the fed tube. The active die movements are controlled by a 6-DOF parallel kinematics
mechanism (PKM) with hydraulic servo drive. Making use of the PKM serves not only to achieve a complete motion
along six axes but also to obtain a high dynamic motion of the bending machine. Application examples show that the
bending machine can be applied to designer's furniture and universal designed products. Until now these processes
have been difficult to achieve using a conventional bending machine.
A New Yaw Dynamic Model for Improved High Speed Control of a Farm Tractor
David M. Bevly and J. Christian Gerdes and Bradford W. Parkinson,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 659-667,
Dezember 2002
view abstract
This paper presents the system identification of a new model for the farm tractor's yaw dynamics in order to improve automatic control at higher speeds and understand controller limitations from neglecting these dynamics. As speed increases, higher order models are required to maintain accurate lateral control of the vehicle. Neglecting these dynamics can cause the controller to become unstable at the bandwidths required for accurate control at higher speeds. The yaw dynamic model, which is found to be dominated by a second order response, is identified for multiple speeds to determine the effect of velocity on the model. The second order yaw dynamics cannot be represented by the traditional bicycle model. An analytical derivation shows that the model characteristics can, however, be captured by a model consisting of a significant (non-negligible) relaxation length in the front tire. Experimental results are presented showing that the new yaw dynamic model can provide lateral control of the tractor to within 4 cm (1sigma) at speeds up to 8 m/s. These results are shown to be an improvement, at high speeds, over controllers based on models (such as a kinematic model) previously used for control of farm equipment.
An Experimental Investigation of Energy Saving Hydraulic Control System Using Switching Type Closed Loop CPS
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
K.-K. Ahn and B.-S. Oh,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 153-157,
April 2005
view abstract
It is strongly requested to reduce fuel consumption because of high oil price and exhaust gases of road vehicles for
environmental preservation. To solve these problems, several types of hybrid vehicles have been developed. Among them,
flywheel hybrid vehicle using variable displacement pump/motor was already proposed as one of the feasible hybrid
systems in place of hybrid vehicle by the conventional Storage battery. The proposed flywheel hybrid vehicle is to keep constant pressure of high pressure line by control of swash plate angle of flywheel pump/motor as pressure compensator. The efficiency of the overall system depends severely on the efficiency of hydraulic pump/motor in the energy saving hydraulic control system. According to the control methods of swash plate angle of piston pump/motor, there remain several problems to be solved.
In this paper, a switching type closed loop CPS is newly proposed in order to improve the energy efficiency and working
condition of hydraulic pump/motor. Newly proposed switching type CPS is a closed loop system and switches the high pressure line according to the operating conditions of the vehicle. The proposed switching type closed loop CPS was verified experimentally to be effective in the energy saving and reduction of pressure fluctuations in the high pressure line, particularly between acceleration and deceleration.
AN EXPERIMENTAL INVESTIGATION OF THE FLOW INSIDE A HYDRAULIC VALVE BY MEANS OF LASER MEASUREMENT TECHNOLOGIES
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
S. Bruno and G. Del Vescovo and A. Lippolis,
2006,
volume 2,
pp. 445-454,
Juni 2006
view abstract
In recent years, the analysis of the fluid dynamic phenomena inside the hydraulic valves has become very important in
order to optimize the spool shapes and to obtain the desired flow metering characteristics.
The Fluid-Power research unit from Polytechnics of Bari has realized many works dealing with the CFD
(Computational Fluid Dynamics) analysis applied to the fluid dynamic behaviour inside directional control valves.
Besides, experimental measurements have been performed in order to validate the numerical results, but the validation
is limited only to the global values as the flow rate discharged by the metering section and the flow force acting on the
spool.
Obviously, more accurate measurement systems are needed to investigate the local flow conditions inside the valve.
To this aim, laser anemometry systems (PIV: particle image velocimetry and LDA: Laser Doppler Anemometry ) have
been purchased.
A valve model, equipped with a great optical access has been realized. The scaled model has been created according to
fluid dynamic similarity laws in order to use a fluid different from the oil (water) and to increase the dimensions of the
valve.
In particular, this model has a circumferential development useful to acquire important data about the circumferential
flows and their effects on the global flow rate crossing the valve. In the past, these flows were studied by means of CFD
codes. The experimental measurements will provide in the future a correct validation of the numerical results.
An Experimental Investigation on the Contamination Sensitivity of an Automotive Fuel Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J.-C. Lee and H.-M. Shin,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 139-144,
April 2005
view abstract
This study addresses the contamination sensitivity test of a typical fuel pump for automotive vehicle. The objective of the study is to find the contamination sensitivity coefficient of fuel pump on specific contaminant particle sizes so that optimal fuel filter could be selected. To achieve the objective, the degradation of discharge flow rate of fuel pump was measured under the experiments of various contaminants size ranges of ISO test dust up to 80um. The fundamental theory of contamination sensitivity was introduced and the contamination sensitivity coefficients were estimated using the experimental data. Maximum contamination sensitivity coefficient of 5 x 10^-6 l/min. Ea was found on the contaminant size range of 40um~50um. The magnified picture of the surface of vane disc revealed that the abrasive wear was the principal cause of discharge flow rate degradation. Hence, this study revealed that high efficiency filter on the contaminant particle size range of 30um~70um especially should be used to maintain the service life of the fuel filter.
An experimental, numerical and theoretical study on valve chatter
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
C. Bazsó and C. Hős,
2010,
pp. 493-504,
September 2010
view abstract
Pressure relief valves tend to become unstable even under steady-state system conditions. The amplitude of the oscillation is usually so large that the valve body hits the seat, which results not only in high noise level but also in severe damage of the elements. This paper presents a theoretical, numerical and experimental study on relief valve chatter. Experiments were performed with an especially simple direct-operated relief valve. The acceleration of the valve body and pressure time histories at the two ends of the transmission line were recorded and it was found that in the range of low flow rates a relatively constant frequency is present due to the oscillations of the valve body. Several series of measurements were performed with different set pressures, the results are interpreted in terms of waterfall diagrams, with flow rate as the parameter being varied. In
the mathematical modeling, the valve body was considered as a one-degree-of-freedom oscillating system. The fluid model was linearly compressible, its inertia, the friction and the unsteady wave effects were neglected. The discharge coefficient was considered as constant. Linear stability analysis was performed on the model yielding an analytical estimation of the onset of self-excited oscillations. Numerical simulations were also performed on this model, with a measurement-based discharge coefficient model. The stability limit was also located numerically. A reasonable agreement was found between the numerical, theoretical and analytical stability borders.
An Experimental Result on the Measurement of Concentrated Flow Resistances
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2005
B. Manhartsgruber,
John Wiley & Sons,
ed. D. N. Johnston and C. R. Burrows and K. A. Edge,
2005,
pp. 427-436,
view abstract
Current developments in fuel injection, variable engine valve actuation systems, and related fields of technology result in an increasing demand for accurate and fast simulation methods for fluid flow in networks of small pipelines or bores within valve manifolds. Besides the description of the flow in straight pipes, the understanding of the influence of elbow fittings, branch connections, intersecting bores, and the like is crucial for an accurate prediction of the dynamic behaviour. While there is a vast literature on the steady state pressure drop of hydraulic components, the dynamic case is poorly understood even for pulsatile laminar flow. The paper gives experimental results on the input output behaviour of test case including a single pipeline with a concentrated flow resistance at the connection between the pipe and a cavity of comparatively large diameter as well as minor concentrated losses due to the mounting points of pressure sensor. Results are given in the form of frequency response functions up to 2 kHz for the test case with a pipe length in the order of one metre.
AN IMPROVED DYNAMIC MODEL OF PNEUMATIC ACTUATORS
J.-C. Maré and O. Geider and S. Colin,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 37-47,
Oktober 2000
view abstract
An improved predictive model of pneumatic jacks is introduced in order to develop a component oriented model library
for the numerical prototyping of pneumatic actuators. First, the valve orifices model is derived from the ISO standard
as a function of the orifice opening. Then the gas chamber behaviour is modelled using a rigorous theoretical development
of conservation laws. Consequently, no assumption is required concerning the evolution of the gas only being
considered as ideal. A fix parameter convective model is found acceptable to define the heat exchange between the gas
and the jack environment. Finally, a representation model of the internal jack friction is proposed including the influence
of pressure and working quadrant on viscous and Coulomb effects. The simulation structure is then presented and the
model is validated using a step by step procedure.
An Improved Mathematical Model For Torque Losses in a Low Speed Hydraulic Motor
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
X. Dong,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 591-594,
November 2003
view abstract
Modeling the torque losses in low speed high torque (LSHT) hydraulic motors has been a
challenging problem for researchers due to the existence of strong nonlinearity and
performance instability at low speed (500 rpm and less). In this paper, an improved
mathematical model is proposed to evaluate the stationary characteristic data of a gerotor orbit
motor. The proposed model incorporates the effect of complicate interaction between pressure
differential and input flow. Subsequently, a new coefficient model is formulated and can be
utilized to analyze the hydraulic performance of the gerotor orbit motor and estimate its
torque output over its wide range of the operation. The new nonlinear model is applied to a
Parker TF0240 gerotor orbit motor. Based on experimental results, all coefficients of a
mathematical model are identified and the model is validated to estimate the torque output of
the motor over its entire operating range.
An innovative pneumatic mini-valve actuated by SMA Ni-Ti wires: design and analysis
M. Tiboni and A. Borboni and M. Mor and D. Pomi,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2011,
volume 225,
pp. 443-451,
Mai 2011
view abstract
This paper presents a proof of concept study on an innovative pneumatic mini-valve. The novelty aspect lie in the creation of an actuation device based on wires formed from the shape memory alloy (SMA) Ni-Ti and in the shape of the body of the valve, with its very limited dimensions being made possible by its construction using mouldable polymeric materials. The proposed device has the following advantages: easy assembly, compactness, silent functioning, bio-compatibility, low power activation, and it is cheap to produce. Extensive static and dynamic characterizations of the valve are performed using a dedicated test rig. Several different valves were measured to ensure measurement reproducibility. The static characteristics of the SMA-based valve are equivalent to those of commercially available valves. A 10ms activation time and a 90ms settling time are obtained at a 30 per cent duty cycle and a 1.5Hz frequency.
An Integrated Approach to the Design and Maintenance of Pneumatic Power Systems
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
K. K. Kong and C. W. Chuen and T. T. Wong,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 151-156,
November 1997
view abstract
An integrated knowledge representation for the design, diagnosis and maintenance of physical systems has been developed. This approach can minimize the redundancy of represented knowledge in building expert systems
for the design and maintenance of physical systems. In the knowledge of human beings, the design knowledge, diagnosis knowledge and maintenance knowledge of the physical systems are integrated and can be retrieved as required. A thorough analysis on the knowledge of human beings has been
carried out in order to determine the critical points which enable the human beings to design, diagnose and maintain physical systems. "Change Theory" is developed to explain the natures of knowledge and the relations among
design, diagnosis and maintenance knowledge of physical systems. The natures of knowledge consist of sensation-state-change identification and sensation-state-change initiation. The clustering of the state changes gives rise to different types of knowledge. An integrated knowledge representation
for building expert systems is developed with features that keep the redundancy of represented knowledge to a minimum. These features are: i) the knowledge base of the expert system is separated into the knowledge of entities and the knowledge of manipulating the entities; and ii) the inference
engine of the expert system is context dependence, which retrieves the corresponding knowledge by checking the preference and non-preference status of the states of the entities. The developed methodology is implemented
on an expert system which exhibits design, diagnosis and maintenance of pneumatic power systems.
An Integrated Fluid Concept - Delivering a Machine that Requires No Oil Change
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
M. Krstić,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 103-116,
März 2010
view abstract
Before being able to reply directly to the question of whether it is possible for a machine not to need an oil change, one must consider which types of oil are generally required in the operation of a machine. Viewing machines in their entirety, i.e. earthmovers, vehicles as well as production machinery in industry, and taking into account importance and quantity, we rank oils in the following order: Motor oils, Hydraulic oils, Gear oils
The integrated fluid concept as developed by KLEENOIL PANOLIN AG covers applications where all three of the above oils are in use. All other oil types and lubricants tend to be lesser in quantity and/or similar in type to the above oils.
AN INVESTIGATION INTO EFFECT OF GROOVE LENGTH AND BUFFER VOLUME ON PRESSURE AND FLOW RIPPLES OF AN AXIAL PISTON PUMP
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. K. Seeniraj and R. S. Chandran,
2004,
pp. 519-529,
Juni 2004
view abstract
Hydraulic systems are commonly employed in industrial and mobile applications due to their power density, quick response and reliability. One of the main components in a hydraulic system is the pump. For robust applications requiring high operating pressure and high flow rate, axial piston swash plate pump is the commonly used variety. Axial piston pumps are complex in design, but can provide a range of pressure and flow characteristics. One of the important factors (currently) impacting the use of hydraulic systems is the noise generated by the pumps. Noise generation in an axial piston pump can be attributed to two main causes – ‘fluid causes’ and ‘mechanical causes’. The mechanism of pumping action and pressure variation inside each piston are the main reasons for pump noise. They relate to fluid causes through flow and pressure pulsation, which propagate through the system and to mechanical causes by inducing cyclic strain causing the pump components to vibrate. The above said problem has been investigated by a number of researchers in their unique way. The general methodology adopted for noise reduction in pumps was providing relief grooves, precompression, and ideal timing of valve ports. The work presented in this paper attempts to investigate noise reduction by combining two well known strategies – providing relief grooves and varying port opening. Also a discussion on the effect of varying the outlet buffer volume of a pump on pressure pulsation was also included.
AN INVESTIGATION INTO MICRO- AND MACROGEOMETRIC DESIGN OF PISTON/CYLINDER ASSEMBLY OF SWASH PLATE MACHINES
M. Ivantysynova and R. Lasaar,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 23-36,
März 2004
view abstract
This paper presents main results of an investigation of the tribological system formed by the piston/cylinder assembly
of swash plate axial piston machines. Main focus has been given to the influence of a piston macro and micro geometry
variation on energy dissipation generated by piston/cylinder assembly. Using the simulation tool CASPAR, which
has been developed at the Institute for Aircraft Systems Engineering, an optimization of the piston shape has been realized to achieve minimum energy dissipation in a wide range of operating parameters of the axial piston machine. Micro
geometry stands for surface roughness here. Its influence has been investigated within a second task especially in the
area of low speed, where full lubrication is not achievable and therefore mixed friction occurs. For the investigation a
special friction force measurement test rig has been developed, which has also been used for verification of the simulation
tool CASPAR.
An Investigation Into the Characteristics of a Two Dimensional "2D" Flow Control Valve
J. Ruan and R. Burton and P. Ukrainetz,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 214-220,
März 2002
view abstract
In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli's forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve (defined as a two dimensional or "2D" flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve's static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.
An Investigation of a Roll Control Suspension Hydraulic Actuation System
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
J. Darling and L. R. Hickson,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 49-54,
November 1998
view abstract
It is recognised that roll control suspensions offer a partial
solution to the well known compromise between ride and
handling. In this paper a simulation and experimental study
of a vehicle with a roll control hydraulic actuation system is
presented in which a variety of ways to reduce power
consumption and cost are investigated. The introduction of
dead-band into the control system can reduce power
consumption while a proportional valve with a spool
configuration which interconnects the load and tank ports
when in the null position is shown to improve ride comfort
and raise the system damping during conditions when the
vehicle is subjected to aerodynamic lateral side loads. In the
prototype vehicle it is argued that the system pressure could
be reduced to levels similar to those of existing power steering systems, if the actuation system control gains are chosen appropriately.
An Investigation of Hydraulic Fluid Properties and Low-speed Motor Efficiency
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
P. Michael and K. Burgess and E. Radle and T. Wanke and M. Devlinand K. Hux,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 341-353,
März 2010
view abstract
This paper presents an investigation of the fluid properties that affect low-speed efficiency in hydraulic motors. Low speed motor efficiency is important because it often determines the pump displacement and operating pressure requirements of mobile hydraulic systems. The boundary friction, mixed-film lubrication, and pressure-viscosity properties of prototype fluids have been characterized. These hydraulic fluids have been evaluated in geroler, axial piston, and radial piston motors under low-speed high-torque conditions in accordance with the ISO 4392-1 standard test method. Correlations between motor efficiency and fluid boundary friction, traction, and pressure-viscosity coefficients were observed. The results indicate that properties other than viscosity can have a profound effect upon low speed hydraulic motor efficiency.
A Nonlinear Control Concept for Hydraulic Servo-Drives Based on a Singular Perturbation Analysis
Proceedings of the International Scientific Forum on Developments in Fluid Power Control of Machinery, Cracow, Poland
B. Manhartsgruber,
1998,
pp. 116-118,
Juni 1998
view abstract
This paper deals with the development of a nonlinear control concept for a hydraulic servo-drive consisting of a heavy mass in translatory motion, actuated by a hydraulic piston and a fast control valve. The load consists of known position and velocity dependent forces and of unknown disturbances. Friction forces of the hydraulic cylinder up to 10 % of the available hydrostatic force are considered.
An open-source Modelica library of fluid power models
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
C. J. J. Paredis,
2008,
pp. 77-90,
September 2008
view abstract
In this paper, a new open-source library of fluid power models is introduced. The intent of the library is to formally collect knowledge about fluid power components and systems, and to share and communicate this knowledge openly among the members of the fluid power community. The library takes advantage of the object-oriented features of the Modelica language to formulate the models in a formal, modular and reusable fashion. The models range from low-level fluid models and models for physical flow phenomena to models for specific fluid power components and systems. In this paper, the key features of the library are highlighted and illustrated with examples.
An Optimum design method of new types of multiple volume resonators for hydraulic pulsation attenuation in real hydraulic systems
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
T. Ichiyanagi,
2004,
pp. 247-254,
Juni 2004
view abstract
The new multiple volume resonators have been developed in the previous paper. These devices can make
up the desired plural resonance modes freely with a single closed-end tube configuration. This paper
presents the optimum design method of the present silencer for a real hydraulic system. In order to
attenuate the pressure pulsation effectively in a real hydraulic system, the insertion loss or the peak
amplitude of pressure pulsation, which are both dependent on the wave propagation characteristics of all
the circuit elements including the silencer, is used as the constraint condition in the optimum design
method. The appropriateness of the present optimum design method and the pulsation attenuation
capability of the present silencer are examined by the fundamental experiments in the test hydraulic
systems equipped with every key circuit design factors of practical hydraulic systems.
A Novel Antioxidants-System for Ester Based Lubricants
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
X. Zhang and H. Murrenhoff,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 477-480,
April 2005
view abstract
In this work, a novel environmentally friendly antioxidants-system composed of two antioxidants, 2,6-di-tert-butyl-4-methyl phenol (BHT) and natrium ascorbate (NaVc), was developed, and the oxidative inhibition for trimethylolpropane-tri-oleate (TMPO) was evaluated by using Rotary Oxygen Bomb Test (ROBT). The results show that this antioxidants-system can obviously extend the oxidation life of TMPO because of a synergistic effect between these two antioxidants. Moreover, this synergistic effect can be improved by metal ion catalysis with the existence of water to some degree. That reduces the accelerating effect of metal ions and water on the oxidation process of ester based lubricants. This novel antioxidants-system makes it possible that the contradiction between the biodegradability and technical requirements can be gradually solved with the development of additives for environmentally friendly biodegradable lubricants.
A Novel, Compact Compensator to Reduce Pressure Pulsations in Hydraulic Systems
Proceedings of ICANOV - International Conference on Noise, Acoustics and Vibration, Ottawa, Canada
J. Mikota,
2001, August 2001
A Novel Concept for a Fast Switching Positioning Actuator
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
R. Scheidl and N. Krimbacher,
2002, Juli 2002
view abstract
Several specific drive problems ask for an actuation characterised by moving a device a certain distance within
very short time. In such case inertia forces become dominant and drive principles are to be preferred which make
use of the conservative character of inertia losses for saving energy. The application we bear in mind are huge
hydraulic switching valves where the spool has to be moved the switching distance within one millisecond or
less. The inertia forces that have to be overcome increase quadratic with the switching frequency and the
required average actuation power with the third order of the switching frequency if the kinetic energy of the
spool is not recovered in the deceleration phase of the spool motion. The presented actuator which is based on
the idea of a hydraulic spring by exploiting the fluid compressibility, firstly is fitting the requirements for energy
recuperation and, secondly renders a very compact design possible due to the well known high specific force and
high specific power of hydraulic actuation.
A novel high efficiency electro-hydrostatic flight simulator motion system
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
K. Cleasby and A. Plummer,
2008,
pp. 437-449,
September 2008
view abstract
Modem flight training simulators must be equipped with long stroke six degree-of-freedom motion systems that have high dynamic response. For many years electro-hydraulic actuators in a Stewart platform configuration have been found to best meet the performance requirements. However, valve-controlled actuators are very inefficient leading to a large power consumption, and also the need for a substantial cooling system to remove waste energy (heat) From the hydraulic oil. This paper describes a new design of motion system that uses a controlled brushless motor for each actuator, with power transmission via directly driven pumps to conventional simulator hydraulic cylinders. Accumulators are used to store and later recycle high pressure oil when actuators retract. In this way, power consumption has been dramatically reduced (for example From 45kW to 5kW during one representative motion waveform), while retaining the proven characteristics of the cylinder drive. Power consumption is lower, by a factor of between 2 and 4, than an equivalent all-electric solution. The motion system will be supplied for the first time with Boeing 787 simulators to be delivered in 2008. Design details are given in this paper, together with predicted and measured power consumption during a variety of representative cyclic motions.
A Novel Linear Motor with Movable Integrated Permanent Magnets
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
J.-C. Renn and B.-J. Liao and C.-Y. Cheng,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 343-354,
März 2010
view abstract
In this paper, a novel linear motor for fluid power valve technology is proposed and realized. The most significant feature of the newly developed linear motor is the movable pair of permanent magnets that is directly integrated into the output plunger of armature. Compared to the commonly used linear motor, in which the pair of permanent magnets is generally merged into the stator and hence is not movable, this novel design enables the linear output force/stroke characteristic. In this paper, the electro-magnetic software FLUX2D is utilized to develop this new linear motor. Finally, experimental results show that the effective linear stroke of the novel linear motor is around +/-1 mm and the maximal output force reaches +/-16 N for the rated excitation current of +/-1 A. It is expected that such a new linear motor may find some potential application fields in fluid power valve technology in the future.
A Novel Piezoelectric Hybrid Solid-liquid Actuator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: 7-5062-7402-7,
L. Shuli and W. Baichang and J. Zongxia,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 385-388,
April 2005
view abstract
The paper describes a smart hybrid solid-liquid actuator that makes use of a novel piezoelectric driven hydraulic pump. Normally it also involves other components such as an output hydraulic actuator, check valves and an accumulator etc.. The paper reviews basic concepts in hybrid solid-liquid actuation. In order to get a higher performance, a novel smart hybrid solid-liquid actuator is put forward. Subsequently, the structure design, modeling and simulation work are carried out. Furthermore, the system prototype and control performance are analyzed. The simulation results verify the correctness of the novel actuation system. Consequently, the potential applications and future work are discussed.
A Novel Piezoelectric Hybrid Solid-liquid Actuator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Shuli and W. Baichang and J. Zongxia,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 385-388,
April 2005
view abstract
The paper describes a smart hybrid solid-liquid actuator that makes use of a novel piezoelectric driven hydraulic pump. Normally it also involves other components such as an output hydraulic actuator, check valves and an accumulator etc.. The paper reviews basic concepts in hybrid solid-liquid actuation. In order to get a higher performance, a novel smart hybrid solid-liquid actuator is put forward. Subsequently, the structure design, modeling and simulation work are carried out. Furthermore, the system prototype and control performance are analyzed. The simulation results verify the correctness of the novel actuation system. Consequently, the potential applications and future work are discussed.
A Novel Piezoelectric Hydraulic Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Shuli and M. Xianghua and J. Zongxia and Y. Zhigang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 5-8,
April 2005
view abstract
In order to get higher frequency response property, a novel piezoelectric pump is designed. It can be utilized to reduce the pulsation through connecting with noise pump bypass to reduce the flow pulsation by active control, which fluctuation frequency is up to 1000Hz. It also can be used in the integrated actuator, to drive the cylinder directly. Although piezoelectric stack actuators are capable of producing large forces at higher bandwidth, the conventional check valves that operate at relatively low frequencies of less than 200 Hz, and prevent full exploitation of the bandwidth of piezoelectric pumps. The novel piezoelectric hydraulic pump designed excludes any check valves. It produces a pulsating flow according to the voltages exerted on each piezoelectric stack and can function at very high frequencies. The paper focuses on the design, analysis, modeling and simulation of the new pump. An analytical model is developed for the pump, and simulation results, potential applications and future work are discussed.
A novel seat valve with reduced axial forces
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
T. Lauttamus and M. Linjama and M. Nurmia and M. Vilenius,
2006,
pp. 415-427,
September 2006
view abstract
Seat type valves have many benefits but because of unbalanced poppet a big force is required to keep the valve open. Also, they tend to close spontaneously when the pressure difference over the valve increases. Some research has been made to compensate the forces in seat valves, but they have required internal seals which increase friction and make valves less durable. A different approach to compensate static forces is studied in this paper. In this simple valve full pressure forces are present in closed position, but vanish when valve starts to open. Experimental results show that the novel structure has great potential.
A novel system layout for extended functionality of mobile machines
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
T. Stamm von Baumgarten and B. Grösbrink and T. Lang and H. H. Harms,
2008,
pp. 13-25,
September 2008
view abstract
Since the introduction of electronic actuated valves, the demands for application-oriented machine functions in the field of agricultural and construction machinery has continuously grown. As a result of this, the automation of mobile hydraulic systems has gained relevancy. This paper presents steps towards automation of mobile machines such as closed-loop velocity control, adjustable end position damping and flexible workspace zoning with help of integrated position and velocity sensors as well as software-based control. The performance of automation functions such as velocity control depends amongst other things on the dynamic behaviour of the hydraulic power supply. For this reason, this paper will present a hydraulic system which had been developed and implemented at the Institute of Agricultural Machinery and Fluid Power. Consecutively, a new approach for a hydraulic system which is part of a current follow-up project will be presented und discussed.
A Novel Valve Concept Including The Valvistor Poppet Valve
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
B. Eriksson and J. Larsson and J.-O. Palmberg,
2007,
volume 3,
pp. 355-364,
Mai 2007
view abstract
These days, energy efficient mobile fluid power systems are of great interest. A mobile system containing several different cylinder drives supplied with a single load sensing pump (LS−pump) has a number of advantages as well as disadvantages. One of the main advantages is the need only one system pump. This makes the fluid power system compact and cost−effective. A challenge is to keep the hydraulic losses at a low level, especially losses at smaller loads. This paper introduces a fail−safe proportional valve element that is based on the Valvistor poppet valve. Due to the demands of flexibility the poppet valve is bi−directional.
The valve has an innovative hydro−mechanical layout that makes it fail−safe, unwanted lowering loads, for example, never occur. The new valve includes simple sensors that are suitable for identification of mode switches, e.g. between normal, differential and regenerative modes. It is also possible to manoeuvre the system with maintained velocity control in the case of sensor failure. In a less complex system the concept
has benefits as well. For example in systems where fail−safe bi−directional on/off valve are needed, then without mode sensing capabilities.
AN OVERVIEW ABOUT ACTIVE OSCILLATION DAMPING OF MOBILE MACHINE STRUCTURE
R. Rahmfeld and M. Ivantysynova,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 5-24,
August 2004
view abstract
One main current demand for mobile machinery development is the improvement of operator comfort and productivity
in order to be competitive on the global market in the future. Actual trends towards cost effective actuator systems in
offroad vehicles and thereby the use of electrohydraulic actuators reflects also the task of active oscillation damping of the machine structure. In the past several concepts, which differ in hydraulic system, control and sensor strategy, have
been developed. However, the practical use is still minor as in most cases passive oscillation systems, which base upon
high pressure hydro-pneumatic accumulators, are widely used although the component costs and frequent check intervals
are problematic for this technology. This paper presents an overview of research work done in the area of active
oscillation damping technologies for offroad vehicles.
AN OVERVIEW ABOUT ACTIVE OSCILLATION DAMPING OF MOBILE MACHINE STRUCTURE
R. Rahmfeld, M. Ivantysynova,
In Int. Journal of Fluid Power,
2004,
volume 5,
pp. 5-24,
August 2004
view abstract
One main current demand for mobile machinery development is the improvement of operator comfort and productiv-ity in order to be competitive on the global market in the future. Actual trends towards cost effective actuator systems in offroad vehicles and thereby the use of electrohydraulic actuators reflects also the task of active oscillation damping of the machine structure. In the past several concepts, which differ in hydraulic system, control and sensor strategy, have been developed. However, the practical use is still minor as in most cases passive oscillation systems, which base upon high pressure hydro-pneumatic accumulators, are widely used although the component costs and frequent check inter-vals are problematic for this technology. This paper presents an overview of research work done in the area of active oscillation damping technologies for offroad vehicles.
AN OVERVIEW OF MAGNETO- AND ELECTRO-RHEOLOGICAL FLUIDS AND THEIR APPLICATIONS IN FLUID POWER SYSTEMS
A. Agrawal and P. Kulkarni and S. L. Vieira and N. G. Naganathan,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 5-36,
August 2001
view abstract
The rapid change in viscosity of magnetorheological (MR) and electrorheological (ER) fluids subjected to a magnetic
or an electric field, respectively, has attracted the attention of many researchers. However, as MR fluids show
higher yield stress than ER fluids, they have merited more attention during the last few years. In this paper we present an
overview of magneto- and electrorheological fluids, their basic properties, behaviour under different flow types and their
uses in fluid power systems, among others.
ANTI-CAVITATION ANALYSIS IN A FOUR-VALVE INDEPENDENT METERING CONFIGURATION CONTROLLING A HYDRAULIC CYLINDER
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
A. Shenouda and W. Book,
2006,
volume 2,
pp. 433-443,
Juni 2006
view abstract
Conventional hydraulic control systems are controlled by proportional directional spool valve. The construction of the
spool valve is such that a given position of the spool determines the flow in and the flow out restriction sizes. Thus,
metering in and metering out are dependent or coupled. A certain restriction size on the inlet corresponds to a certain
restriction size on the outlet. Therefore, we have one degree of freedom. It can provide for good motion control but it
cannot achieve energy saving potential at the same time.
In this paper, the concept of 'independent meter in / meter out' will be emphasized. Decoupling of meter in from meter
out provides for more controllability and potential for energy saving in overrunning load cases when compared with a
conventional spool valve controlled hydraulic system. A four-valve configuration controlling a hydraulic cylinder is
stressed. The four-valve configuration can operate in several modes because each of the four valves is controlled
separately from the others. Five of these metering modes will be pointed out and analyzed.
An anti-cavitation analysis for the four-valve independent metering configuration is presented. The load that would
cause cavitation depends on the metering mode in which the valve configuration is operating and on the inlet to outlet
valve openings ratio. An expression that determines the cavitation-causing load as a function of valve coefficients ratio
is derived for each of the five modes. That expression can be used by the controller to determine dynamically how to
change the valve openings ratio to prevent cavitation as the load changes.
A numerical model for the simulation of a special poppet valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. Franzoni and A. Vacca and P. Casoli,
2004,
pp. 165-174,
Juni 2004
view abstract
This paper describes the simulation model of a special poppet pressure control valve developed in
cooperation with Casappa S.p.a. The model is based on a lumped parameter framework, in this way it
complies with the requirements of simplicity, simulation swiftness and versatility. The model has been
validated by experimental investigations; the tests were performed in different steps and, on the basis of
the experience achieved by means of both experiments and simulations, several prototypes were
manufactured and tested in order to make the validity range of the model wider. The model calibration
was also aided with some CFD simulations. The paper highlights the large versatility of the model by
comparing test results with numerical outputs; namely the model permits to study the influence of several
geometric parameters on the flow characteristics, thereby enhancing its potentials as a design tool for this
kind of valve.
A numerical model for the simulation of flow in hydraulic external gear machines
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
P. Casoli and A. Vacca and G. L. Berta,
2006,
pp. 147-165,
September 2006
view abstract
The present paper describes a numerical model, developed by the authors, for the simulation of external gear pumps. The model has been implemented in AMESim® environment, developing new in-house C++ models.
The fluid dynamic model is based on a finite volume framework. The pump is described with a geometrical sub-model, which yields the actual values of the variable volumes (defined by teeth, housing, and side wear plates) and of the throat areas, as functions of shaft position. The model allows to predict the pressure evolution inside each tooth space, while considering cavitation and leakages in a simple manner. After pressure inside each tooth space is known, the forces suffered by the gears and the torque required to drive the pump are determined. The results have been verified through comparisons with some experimental data.
A Parameter Study of a Digital Pump
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Jaurola and K. Huhtala,
2010,
pp. 203-215,
September 2010
view abstract
The studied digital pump differs from traditional hydraulic pumps in its flow control method. Instead of using a valve plate or hydraulically operated check valves, the direction
of the flow in a reciprocating element of a pump or motor can be governed with electronically controlled ON/OFF valves. Active ON/OFF valve control allows programmability which in this case means that each reciprocating element can act as a
pumping, motoring or an idling element. Therefore hydraulic power can be transferred from one outlet to another. Another benefit compared to a traditional valve plate is that the precompression and decompression of the fluid during the work cycle can be adjusted independent of the pressure at the outlet. This feature allows the optimization of the flow
ripple at the pump outlet.
A simulation model of a digital pump was built with a commercial software GT-Suite 7.0 and the model was verified with cylinder pressure measurements of a digital pump. Besides
concentrating on detailed modeling of the flow paths in cylinder head blocks, also the characteristics of the active control valves are verified for the pump model. The model is
then used to study the pressure ripple behavior inside pump cylinder and in pump outlet when active control valve parameters (e.g. nominal flow rate, response time) are varied.
In this paper the simulated results of the pressure ripple study are presented. Also the verifying results comparing the measured and simulated results are included. The results of
the study will be used in the future studies of the digital pump-motor transformer (e.g. controller studies and optimizing the components).
A Piezoelectric Micropump Using Resonance Drive: Proposal of resonance drive and basic experiments on pump characteristics
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
J.-H. Park and K. Yoshida and S. Yokota,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 77-82,
November 1997
view abstract
In this study, a piezoelectric micropump using resonance drive is proposed and fabricated. Fabricated piezoelectric micropump basically consists of a bellows acting as a reciprocating pump chamber, a multilayered PZT actuator for oscillating the bellows and normally closed cantilever type of two check valves. Frequency characteristics of flow rate and pressure are investigated with different amount of additional mass. Furthermore, output characteristics of the pump are investigated when a bellows is attached to the outlet as a varying load. Through those experiments, it is ascertained that the maximum flow rate with no load pressure is about 100mm³/s, the maximum output pressure is about 0.25MPa and the maximum output power of the fabricated pump is about 4mW. As a result, the feasibility of the piezoelectric micropump with resonance drive is confirmed.
A Pneumatic Climbing Robot for Inspection Tasks
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
E. Ravina,
2007,
volume 2,
pp. 25-34,
Mai 2007
view abstract
The paper refers on an application research oriented to the design and realisation of climbing robots able to automously move their selves using pneumatic devices. The purpose is the design implementation of low cost service robots, conceived for inspection tasks on different kind of surfaces. The main characteristics and potentialities of original prototypes designed, realised and tested are focussed and discussed, showing application advantages and operation limits.
A Pneumatic Force Reflector in Bilateral Control System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
X. Li and Y. Chen and J. Zhang and J. Gao,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 849-853,
April 2005
view abstract
Force reflector is widely used in bilateral control systems as a force feedback tool. In this paper a pneumatic force reflector has been put forward, based on the analysis of the Internet based bilateral control system. This paper has adopted a passive force generation mechanism, so that the valve controlled cylinder positioning system can be used as both the force reflector and the transducer of the operator's response. Another advantage of this force reflector is that it avoids modeling the human operator and thus keeps system stable and easy to operate due to the passivity of it. The mechanism on how to generate required feedback force using the pneumatic cylinder has been discussed, together with its control model and implementation. Several experiments have been conducted based on a teleoperation use case: the human operator using this force reflector to control a pneumatic robot through the Internet. The experimental results are provided in this paper, followed by a detailed discussion.
A Pneumatic Library for AMESim
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
E. Bideaux and S. Scavarda,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 185-195,
November 1998
view abstract
The present development of the simulation and virtual prototyping actually has lead to the development of specialized software packages to industries using fluid power based components as the truck, railway or car industry. These specialized packages such as AMESim (Advanced Modeling
Environment for performing Simulations), consist of a robust solver and multidisciplinary libraries of models, since the solving method is strongly linked to the simulation aim and the modeling step itself.
AMESim has already proposed hydraulic and one-dimensional mechanical components and some useful tools for the study of fluid power systems. As strong links exist between hydraulic and pneumatic technology, we have implemented a library of pneumatic components that could be used in connection with the other existing libraries. The models arise directly from our pseudo bond graph knowledge and our experience of measuring existing pneumatic components. The first library (the Basic Elements Library) contains the basic elements: sources, modulated dissipative elements, modulated transformers, capacitive elements, sensors, which allow the simulation of any pneumatic based system. In the second library called the Elementary Component Library, we propose a
selection of standard components such as relief valves, distributors, servo-valves and spools. The third and last library is the Advanced Component Library and it consists of models for specialists such as pipes, variable volume chambers, and more complex components.
In this paper, we propose an overview of this library of pneumatic components and we show its possibilities by simulating of an existing pneumatic systems.
A PORTABLE FLUID POWER SIMULATION MODEL LIBRARY AND ITS APPLICATION
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
J. Larsson,
2006, August 2006
view abstract
The paper presents a fluid power model library in the equation-based modelling language Modelica and shortly
shows how the library can be used in simulation software such as Matlab. The library is built such that valves and actuators
can be built by engineers rather than simulation specialists and so that it is possible to compile into executable code
with as little effort as possible.
APPLICABILITY OF A LAMINAR FLOW BASED MODEL IN PIPEFLOW MODELLING OF WATER HYDRAULIC SYSTEMS
T. Leino and M. Linjama and K. T. Koskinen and M. J. Vilenius,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 37-46,
August 2001
view abstract
Turbulent flow in pipes is usually avoided in traditional oil hydraulics. However, using water as a hydraulic
fluid, the flow can be regarded as turbulent and the Reynolds number is usually between 10000 and 200000. Most
of the pipe models are formed assuming the flow to be as laminar. One pipe model has been developed using a
variational method and modal approximation. In this research the applicability of this model to simulate strongly
turbulent pipe flow has been studied. The comparison between the simulated and measured results is made in time
domain. These results show that this pipe model can be used in practical designing also when the flow is turbulent.
Applicability of servopneumatic positioning systems for high loads
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
Y. E. A. Mendoza and L. G. de Oliveira and V. J. De Negri,
2008,
pp. 219-232,
September 2008
view abstract
This paper analyzes the applicability of a servo-pneumatic positioning system in the presence of high loads. The model of the servo-valve which includes the non-linear relationship between the mass flow with pressure and electric voltage is presented. Regarding the cylinder modeling, the friction is successfully described with the use of a variable viscous friction model. Based on the model, the system design from the static and dynamic viewpoints is discussed and the theoretical-experimental analysis of a system aimed at the position control of hydraulic turbine blades with 12000N of loading is performed. A classic PID controller with dead-zone compensation of the servo-valve enabled fully satisfactory performance in relation to the settling time and position error established by international standards for power plant control. Thus, the applicability of servo-pneumatic technology with high load was verified and an alternative solution to the hydraulic technology currently used in electrical power plants is proposed.
APPLICATION OF A COMBINED SLIDING MODE CONTROLLER AND FILTER (SMCF) TO AN ELECTROHYDRAULIC ACTUATOR (EHA) SYSTEM
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
S. Wang and R. Burton and S. Habibi,
2006,
volume 1,
pp. 101-116,
Juni 2006
view abstract
This paper deals with energy efficient mobile valves with cylinder loads. In recent years, the need for energy efficient
fluid power systems has increased. The reason is the increasing price of oil as well as tougher environmental
regulations. One way of achieving an energy efficient directional valve is to use individually controlled meter-in and
meter-out orifices and transfer functionality from hardware to the software controller. This type of solution makes it
possible to keep metering losses low. Energy recovery is also made possible since both speed and lowest cylinder
chamber pressure can be controlled. The challenge in such a controller is to decouple the chamber pressures in the
MIMO (multi-input-multi-output) hydraulic system into independent SISO (single-input-single-output) systems. In this
paper, a decoupling based on a linear analysis of the physical system has been implemented and tested in a cylinder
position control application. The controller is evaluated in terms of performance and robustness. In the near future, this
project will continue with other approaches as well, as there are several interesting control approaches available.
Application of a Neural Network in a Hydraulic Servo Systemwith a Flexible Load
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
Y. Liu and T. Nishiumi and H. Handroos,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 523-533,
November 2003
view abstract
The paper presented an application using neural network for a hydraulic servo system with a flexible load. With the capability of mapping all kinds of nonlinear elements from artificial neural network, the neural network acceleration feedback control with constant gain characteristic is embedded with the inner loop line of the position control for the nonlinear dynamic system. A model reference control approach is used for adapting the control system. The proposed controller, which is a combination of a proportional controller and neural network is firstly trained on-line by simulation and secondly it is applied the hydraulic servo system with a flexible load. Some results of the system performance are given.
Application of an Optimal Control Synthesis Strategy to an Electro-Hydraulic Positioning System
Richard D. Abbott and Timothy W. McLain and Randal W. Beard,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 377-384,
September 2001
view abstract
Successive Galerkin Approximation (SGA) provides a means for approximating solutions to the Hamilton-Jacobi-Bellman (HJB) equation. The SGA strategy is applied to the development of optimal control laws for an electro-hydraulic positioning system (EHPS) having nonlinear dynamics. The theory underlying the SGA strategy is developed. Equations of motion for an EHPS are presented and simulation results are compared with those obtained experimentally. Results demonstrating the experimental application of the SGA synthesis strategy to an EHPS under a variety of operating conditions are presented. These results are compared to those obtained from a linear quadratic regulator developed from linearized model equations.
Application of Bond Graph Notation in Modelling of Nonstationary Temperature Field
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
W. Cichocki,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 209-226,
view abstract
No abstract available
Application Of CFD To Design A Power-Saving Hydraulic Directional Two-Land-Four-Way Valve
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
J.-C. Renn and T.-C. Kao,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 83-94,
November 2003
view abstract
In this paper, a simple hydraulic two-land-four-way directional solenoid valve is chosen for
the study of the possibilities to compensate the flow force as well as to reduce its energy
consumption. Because the flow force acts against the driving magnetic force and tends to
close the opening orifices inside the valve, a portion of the solenoid’s output force is wasted
to overcome this reverse action of the flow force. Consequently, the design of an energysaving
directional solenoid valve is possible, if the flow force is reduced or even eliminated in
the design process. Therefore, the flow force in the tested valve is formulated and a newly
designed spool is fabricated. A simplified analytical model using CFD-analysis is also
developed, which shows that the total flow force in the tested valve with the new spool is
reduced by 27 %. Finally, a series of experimentals are carried out and the results show that
the tested solenoid valve with the proposed new spool can be operated at a lower supply
voltage, which means that the energy consumption is successfully reduced.
Application of dc Servomotor on Airflow Measurement
Thananchai Leephakpreeda,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
März 2010
view abstract
The aim of this research paper is to systematically present an optimal control of a dc servomotor for the airflow measurement in both the magnitude and the direction. During measuring airflow, the dc servomotor drives a paddle around the rotor axis in a field. The torsional load of the dc servomotor is caused from resistance of the airflow over the moving paddle normal to the flow. The variations on the torsional load in one revolution of rotation can be characterized from the magnitude and direction of the airflow. In other words, the magnitude and direction of airflow cause a periodic function of the torsional load with respect to the angular position of the paddle. By using Fourier analysis, it is found that the magnitude and direction of the airflow can be determined from the coefficients of the Fourier series. Typically, the torsional load of the dc servomotor, unlike the rotor speed, cannot be measured by the built-in device. In this work, it is determined by applying the extended Luenberger observer method. A state-feedback controller with the observer based on H2 control design is implemented to regulate the dc servomotor. The experimental results on the measurement of airflow show the viability of the proposed methodology.
Application of Differential Evolution in system identification of a servo-hydraulic system with a flexible load
H. Yousefi and H. Handroos and A. Soleymani,
In Mechatronics,
2008,
volume 18,
pp. 513-528,
November 2008
view abstract
Electro Hydraulic Servo Systems (EHSS) are commonly used in industry. The systems are non-linear in nature and their dynamic equations have several unknown parameters. System identification is a prerequisite to analysis of a dynamic system. One of the most promising novel evolutionary algorithm for solving global optimization problems is the Differential Evolution (DE) algorithm. The DE algorithm is proposed for handling non-linear constraint functions with boundary limits of variables to find the best values for the unknown parameters of a servo-hydraulic system with a flexible load. The DE algorithm guarantees fast speed convergence and accurate solutions regardless of the initial conditions of parameters. Several tests are carried out to validate the accuracy of selected unknown parameters. The results indicate good agreements between the related simulated and measured states.
Application of Electrohydraulic Direct Digital Servo in Metal Extension Test Machine
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
R. Jian and Y. Zheqing and R. Burton and P. Ukrainetz,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 89-93,
April 2005
view abstract
Fine controls of stress rate, strain rate and elongation speed are demanded in the extension test of metallic material to correspond to three distinct elongation stages: elastic, yielding and reinforcing. For the hydraulic extension test machine, the loading to the specimens is carried out by an electrohydraulic servo control system, in which the extension of the material is controlled and automatically switched to the different control modes by a control valve. Since the valve plays a key role of both power amplification and electro-to-mechanical transformation in an electrohydraulic servo system, it dominates to a large extent the performance of the whole control system. On the other hand, being a test device or equipment, the extension test machine is demanded to possess high-accuracy for its electrohydraulic servo control system. According to the Chinese National Standard, the error rate for constant force control should be less than 0.2% and that of the force rate less 0.2%. The demand of the electrohydraulic valve is even higher. For this reason a special electrohydraulic digital valve has been developed and applied in the electrohydraulic servo loading system of the material testing machine to meet the requirement of the National Standard. The strategy for the digital control of the valve is discussed and a comparison between the conventional servo/proportional valve and the digital valve is presented. It is pointed out that the superior of the digital valve to the servo/proportional valve is owed to its characteristics of stage control. The nonlinear error of the digital valve can be lowered to 0.1% by appropriate selection to the stage number of the digital valve to meet the National Standard requirement on control accuracy of the extension test machine.
Application of Fluid Power Devices in Active Vibro-control Systems
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
St. Michalowski,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 281-328,
view abstract
No abstract available
Application of Hydraulic Power Unit and Accumulator Charging Circuit for Electricity Generation and Storage and Distribution
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. N . Okoye and J. H. Jiang and Z. D. Hu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 224-227,
April 2005
view abstract
It is the purpose of the present paper to investigate the level of electricity generation, storage and transmission of hydraulic power unit with charging accumulator circuit in order to achieve fluctuation free power generation, cost reduction and power reutilization. The study derives a mathematical model suited to the simulation of the hydraulic accumulator both in an open- or close-loop system. Through the application of the geometrical data and the thermodynamic principle, the model of an ideal hydraulic accumulator emerged. The research was occasioned as a result of lower energy capacity storage and saving/reutilization of the conventional accumulator resulting in the short cycle time usage of hydraulic accumulators both in domestic and industrial purposes.
The basic components are variable displacement pumps driven by electric motors, hydraulic accumulator, hydraulic tank, hydraulic turbine, piezoelectric coated piston cylinder, different type of hydraulic valves including charging valve, control/measuring devices and the main supply and return manifolds. The arrangement enables the pumps to switch from free circulation into accumulator charging function if a specified minimum load pressure in the accumulator fails to be attained. At the end of the closing and charging period, the upper accumulator load pressure is attained and the variable displacement pump switches back into free circulation. This system, which could be called hydraulic pressure power mini net station (HPPNS), could supply the entire electricity demand to a localized group of customers thereby avoiding the cost of transmitting electricity from a distant central-plant power station (CPPS). The system stores hydraulic fluid in a high-pressure storage tanks for electricity generation, which is transmitted to the users when needed. The electricity, which is produced through piezoelectric coated cylinder piston and hydroelectric devices powered by high pressurized hydraulic fluid, is also used to pressurize more hydraulic fluid that is supplied to the high-pressure storage tanks for future use. This method proved that the excess electrical energy generated from the pressurized hydraulic fluid is recycled and stored in high-pressure tank for future use. The research work appears to be very efficient method for generating fluctuation free electricity, power quality and reliability, energy saving/reutilization and system noise reduction.
Application of Hydraulic Power Unit/Flywheel Power for Electricity Generation and Storage and Distribution
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. N. Okoye and J. H. Jiang and Z.D. Hu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 790-793,
April 2005
view abstract
The primary focus of this paper is to develop a new renewable distributed generation (DG) technology by integrating two latent prospective mechanical energy sources (hydraulic power unit with hydraulic charging circuit and flywheel power) for lower emissions, high power density, greater efficiency, improvement of power quality/system cycle life, power storage, reutilization and more stable energy price. The research was carried out as a result of inability of other renewable distributed generation such as fuel energy, micro turbine, solar energy, wind energy among others to absorb power when demands drop and deliver it when demand rises hence could not catch up with the load variations. This result in the break down of sensitive electrical equipment. The integration of flywheel with hydraulic power unit will enable this renewable distributed generation system to follow up load fluctuations, rapid charge capability, power reliability and efficient load following without been connected to the central power grid. The research appears to be very efficient method for power generation/distribution reliability, fluctuation smoothening, energy saving and reutilization.
Application of hydraulic sine generator to active vibration control
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
J.Kostamo and E. Kostamo and J. Kajaste and M. Pietola,
2010,
pp. 175-186,
September 2010
view abstract
Vibration frequencies in rotating industrial machines may range up to several hundreds Hertz and in some specific applications the excitation forces can also be relatively high. These facts set demanding requirements for the devices which can be used to suppress the vibrations in most challenging cases. To overcome these problems a simple method for producing sinusoidal pressure fluctuations is presented in this paper and applied to active vibration control task. The method is based on a hydraulic sine generator designed especially for active vibration control solutions and it is suitable for high frequency and high power actuation. Different concepts for technical implementation are discussed and an experimental device based on a rotating gear plate is presented. The applicability of the device in active vibration control task is verified by experiments and it is shown the device is capable of outputting more than 1 kN force at 1 kHz frequency.
APPLICATION OF NEURAL NETWORKS IN HYDRAULIC CONTROL SYSTEMS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
E. Lisowski and G. Filo,
2002, Juli 2002
view abstract
An analysis of a hydraulic system, which the main purpose is to generate required pressure in the system,
is presented in this paper. The analysed system consists of hydraulic cylinder, control valve with the
electromagnetic controller and proportional relief valve. It is controlled by a neural network controller, so as to
achieve required pressure. A multi-layer neural network was used as the controller with triangular and
rectangular standard signals. The simulation process was carried out using the digital simulation method.
APPLICATION OF PARALLEL CONTROL SYSTEM IN MANIPULATOR'S WORK VISUALIZATION PROCESS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
T. Czyżewski and E. Lisowski,
2008,
pp. 401-408,
Juli 2008
view abstract
The usage of manipulators in industry, medicine and as well in other domains systematically grows up. It is due to
comfort, general work rationalization and outlay decrease. One of most important issue of manipulator’s application is
equivalent system of visualization and work control. This paper presents a proposal of manipulator's work visualization
system with taking advantage of parallel control. The proposed system allows to synchronically manipulating two
robots: physical object which is doing some specified work and its virtual counterpart in CAD system. Control of both
manipulators is realized by using one control panel. Control process is divided into two stages. In stage one the control
signals are sent from the panel to equivalent drives of real manipulator. In stage two, control signals for virtual object
are generated on the basis of signals acquired from position sensors. Next generated signals are sent to CAD system.
Visualization system exploits program Pro/Engineer with Pro/Toolkit technology. Software for control system for both
manipulators, virtual and real, was written in C++. This lecture presents construction of visualization system and also
result of analysis.
Application of proportional seat valves to a self-energising electro-hydraulic brake
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
J. Ewald and M. Liermann and C. Stammen and H. Murrenhoff,
2008,
pp. 481-494,
September 2008
view abstract
A new hydraulic brake utilising a self-energising effect has been developed at the Institute for Fluid Power Drives and Controls (IFAS). The Self-energising Electro-Hydraulic Brake (SEHB) generates the brake pressure by supporting the brake torque via a hydraulic cylinder and hence doesn’t need an external power supply. Until now, the SEHB has been used with seat-type switching valves for control of its brake torque only. Spool type valves cannot be used for SEHB because of leakage in the closed position due to radial clearance.
For high requirements concerning comfort and dynamics this paper presents a valve concept using 2/2 way proportional seat valves. The major advantage over previous concepts using switching valves is the adjustable closed loop gain. As the result of a simulation study regarding the requirements of the target application, a configuration of eight 2/2 way valves is set up. Measurements of the valve tappet’s position with a laser vibrometer show the dynamics of the used valve-types. A map of the flow is measured to regard the pressure dependency in the SEHB controller. The valves are integrated in a compact unit for the SEHB prototype. The paper finishes with first results of closed loop brake force control.
Application of Singular Perturbation Theory to Hydraulic Servo Drives - System Analysis and Control Design
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
B. Manhartsgruber,
M. Ivantysynova,
ed. ,
2000,
pp. 339-352,
September 2000
Application of the Electro-hydraulic Servo System in the Metallurgical Machinery
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Yiqun and Z. Wei and G. Dianrong and L. Jian,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 66-70,
April 2005
view abstract
Modem metallurgical machinery system is the large-scale, high power, continuous production, high automation, and precision working unit, and the electro-servo system is one of the most important parts of the whole system. The electro-hydraulic servo system run 'through the whole process of the production system and provides the favorable technical condition for making the high-quality product. This article introduces several important electro-hydraulic servo control system: the electric furnace control system, the hydraulic oscillatory system of the continuous casting mold, the hydraulic screw-down system of the rolling mill, the roll-bending system, the looping control system, the jumping control system of the coiler etc. The conclusion is that the electro-hydraulic servo system has the characteristic of quick response, high control precision, high capacity, high loading stiffness, and is easy to realize various kinds of control strategy. Therefore, the electro-hydraulic servo system provides effective technical supports for metallurgical machinery modernization.
Application of the Fourier transform for actuator leakage diagnosis
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Goharrizi, Amin Yazdanpanah and Sepehri, Nariman,
2010,
pp. 383-395,
September 2010
view abstract
Application of the Fourier transform, to detect internal leakage in hydraulic actuators is examined. By analyzing the dynamics of the actuator, it is shown that the internal leakage increases the damping characteristic of the system and decreases the Bode magnitude of pressure signal over valve displacement, around the hydraulic natural frequency. This is further confirmed, by decomposing the original pressure signal, using this method, and identifying the frequency component sensitive to the internal leakage. The root mean square of the processed pressure signal is used as a fault indicator. The effectiveness of the proposed approach is shown through experimental results.
Application of the PIV Method to Optimization of the Internal Channels of Gerotor Pumps
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
Piotr Antoniak,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 501-510,
März 2010
view abstract
The displacement gear pumps are widely used in the hydraulic power systems. The group of the displacement gear pumps includes the gerotor pumps. Their achievements are similar to those of the external and the internal involute gear pumps. Only in the field of working pressure the gerotor pumps are worse. One of the experimental methods used to improve the achievements of the gerotor pumps, also in this field, is the Particle Image Velocimetry (PIV). This method makes possible to visualize the flow processes inside the internal channel of the pumps. On the basis of this observation it is possible to determine the velocity range of the flow. The analysis of the velocity range allows the determination of the dangerous areas of the channels (e.q. the area where the cavitation might occur) which should be redesigned. In this article, the application of the PIV method for the optimization of the internal channels of the gerotor pump is going to be shown.
Application of Wavelet Analysis and Fractal Geometry for Fault Diagnosis of Hydraulic Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. Dongning and J. Wanlu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 628-631,
April 2005
view abstract
In this paper, the method of wavelet analysis and fractal dimension calculation is firstly applied in diagnosis of hydraulic pump with shoe-doffing fault. In recent years, fractal dimension is studied by some researchers and is applied in many fields. But some research has shown that the correlation dimension is easily affected by noise. So in this paper the wavelet analysis is applied in the noise elimination of pressure signal. The initial pressure signal is decomposed, noise eliminated, and reconstructed by use of the wavelet analysis method through selecting wavelet function Daubechies 5. The fault characteristic frequency is extracted correctly in its corresponding high frequency coefficient. Then the correlation dimension of the noise-eliminated data is calculated with the G-P algorithm. When the pump outlet pressure is 3MPa, the correlation dimension of signal in normal condition is 1.68, while in fault condition it is 1.35. The result shows that the correlation dimension of signal in fault state is lower than that in normal state. The combination of wavelet and fractal technology can give us an effective method in condition monitoring and fault diagnosis of equipments.
Applications of Haptic Joystick in Control of Electrohydraulic Drives
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
Andrzej Milecki,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 293-304,
März 2010
view abstract
The advantages of haptic joystick application in control of hydraulic drives and devices with such drives is the main reason of work proposed in the paper. This paper presents the state of the art in control of drives with use of force feedback haptic devices. In the paper, we develop a controller of electrohydraulic drive with haptic joystick, in which magnethoreological rotary (MR) brake was applied. The simulation model of such a system was proposed and investigated. The system and its control strategies have been applied in practice and tested. The made out work has shown that haptic control can improve the human feeling of drive and its environment.
Applications of Modelling and Simulation in Mechatronics and Fluid Power System Design - Education and Research
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
T. O. Andersen and M. R. Hansen,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 491-503,
November 2003
view abstract
The development within the engineering industry is ever more in the direction of an
integration of electronics both on the component level and the system level. This implies
improved and more intelligent components with increased functionality at the same time as
the variant creation is made in the electronics and software. On the system level the
component only constitutes part of the functionality and must be adaptable to different
systems. This makes heavy calls on the specification of the concept. In this context control
engineering plays a central role, whose well-established methods forms very powerful
techniques both in analysis and in synthesis of hydraulic systems. Before control engineering
techniques can be applied it is required that hydraulic components and systems can be
described in terms compatible with the language used in control engineering, thus, modelling
and simulation are needed. The objective of this paper is to show how modelling and
simulation and control can be used for analysis and design of mechatronic systems with fluid
power actuation. The focus is on system aspects and describes several projects from education
and research that utilises the above methods.
APPLYING SELF-ORGANIZING MAPS TO CONDITION MONITORING OF FLUID POWER SYSTEMS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
T. Krogerus and J. Vilenius and J. Liimatainen and K. T. Koskinen,
2006,
volume 1,
pp. 311-323,
Juni 2006
view abstract
The goal of this paper is to study a proactive condition monitoring system for fluid power systems where neural network
is used for fault detection. The neural network discussed here is Self-Organizing Map (SOM). Operation of the
proactive condition monitoring system is tested in a test system where two fault types are used. The test system is run in normal and two different fault situations. Measurement results are used for training and testing the SOM. These results and also the output of the SOM are shown in this paper. When fault situations are known before supervised learning
can be used to train the network. In supervised learning targets are used to train the fault situations to the network. If all the damages are not assumed to be known before diagnostics, ordinary neural network with supervised learning for their detection can not be used. Here supervised learning is used and the possibilities of unsupervised learning are
discussed. After training the SOM it is tested first with data from the measurements and finally with the real system.
APPROACH FOR ENERGY-SAVING OF PNEUMATIC SYSTEMS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
T. Arinaga and Y. Kawakami and Y Terashima and S Kawai,
2000,
pp. 49-56,
September 2000
view abstract
The energy-saving for mechanical systems has become an urgent subject from a viewpoint of the environmental
protection. In the pneumatic systems, we also have to make a plan for energy-saving immediately. Therefore we
examine the energy-saving for the pneumatic cylinder, which is the most typical actuator of the pneumatic systems.
Generally speaking, pneumatic cylinders are often driven by PTP (Point to point) driving. There are
meter-out circuit and meter-in circuit to control the driving speed in PTP driving. As we investigated the
responses of the pneumatic cylinders driven by both circuits, it has been revealed that supplied air is wasted
when the piston reaches the stroke end in meter-in circuit. Therefore, we proposed the method for energy-saving
to cut off the supply air when the piston reached the stroke end in meter-in circuit. As a result, the air consumption
can be curtailed by approximately 70%, applying the method to the system. On the other hand, it is considered
that stick-slip motion occurs more frequently in meter-in circuit than meter-out circuit. But by some
experiments, meter-in circuit is not necessarily inferior to meter-out circuit from the view of the occurrence of
stick-slip motion, depending on the driving conditions. These results suggest the possibility of energy-saving by
adopting meter-in circuit.
A PRECISE STEADY-STATE MODEL OF DISPLACEMENT MACHINES FOR THE APPLICATION IN VIRTUAL PROTOTYPING OF POWER SPLIT DRIVES
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
D. Mikeska,
2002, Juli 2002
view abstract
This paper presents a very precise steady-state mathematical model of displacement machines. The used approach is
a pure mathematical one, based on a special polynomial function fitted to measurement data. However this model is
generally suitable for any kind of displacement machines. The main focus was given on swash plate axial piston pump
and their application in power-split drives.
Further, the paper discusses the physical background of significant loss-sources exemplary for a swash plate axial
piston pump. The test-rig is described, which was used for steady state measurements of losses at both, pumping and
motoring modes for a wide range of operational parameters. Selected measurement results of losses are presented. The
software program POLYMOD for the computation of the new model and a graphical comparison of the computed
model with the measurement data is described. POLYMOD-models of volumetric and torque losses were implemented
into Simulink blocks as S-functions (C-code). Additionally, a model of pump system parameters was implemented.
Presented are models of a hydrostatic transmission. This transmission model incorporates two or more displacement
machines. Simulation of simple manoeuvres were carried out on the transmission model with two displacement machines
operating in a closed circuit.
A PRECISION DRIVING SYSTEM COMPOSED OF A HYDRAULIC CYLINDER AND HIGH-SPEED ON/OFF VALVES
S. Tsuchiya and H. Yamada and T. Muto,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 7-16,
März 2001
view abstract
In manufacturing technology, the predominant tendency in recent years has been for machine tools, for example,
turning-, milling-, and drilling-machines, to employ electrically operated actuators such as a servo-motor
equipped with a ball screw. There are, however, various problems with these electric driving systems; they are
excessively large-sized with complex machinery, and their application is expensive, as seen, for example, in the
case of the NC-machine. In order to solve these problems, this study aims to develop a precision driving system
actuated by a hydraulic cylinder. The hydraulic driving system consists of a cylinder and four ON/OFF solenoid
valves. The valves are the same as those used in a fuel injector of an automobile, which are capable of high speed
switching, as fast as 1.5 ms. It was confirmed in experiments that the developed system had a moving resolution
of 1.2 μm and, as a result, was applicable to a precision driving table for micro-processing.
A proposal to compare electro-pneumatic continuous control valves: required main characteristics
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
S. Sesmat and R. de Giorgi and E. Bideaux and D. Thomasset and D. Hubert,
2007,
pp. 431-447,
September 2007
view abstract
Comparative characteristics of components are required to make the adequate choice according to the desired performances or requirements of the system to be designed. This paper proposes to define a set of characteristics, which constitute the needed data for comparing the performances of electro-pneumatic continuous control valves including pressure or flow control valves. These static and dynamic characteristics correspond to the essential information required by users to make a proper choice at the design stage. The associated experimental test rig and procedures for determining these characteristics are also shortly described.
A QUALITATIVE STUDY OF BIODEGRADABLE HYDRAULIC FLUID USE IN SMALL CONSTRUCTION EQUIPMENT
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
P. Pawelski,
2000,
pp. 129-136,
September 2000
view abstract
The demand for construction equipment utilizing biodegradable hydraulic fluid (bio-oil) is increasing in Europe.
Several municipalities have passed ordinances requiring equipment working within the city limits to use bio-oil.
Most of the equipment used in these areas is of the small or compact variety. In order to pack more power into
these small pieces of equipment, they are often designed with hydraulic systems that run at higher temperatures
and pressures than the systems in larger machines. To reduce cost, many of these machines use vented hydraulic
tanks. Because of these differences, the hydraulic systems of small construction equipment provide a harsher
environment for bio-oils than what is seen in larger machines. The Building Construction Products Division of
Caterpillar Inc. ran a series of qualitative tests on a saturated synthetic ester bio-oil to determine its usability in
the small and compact construction machines manufactured by the division. Testing was conducted using small
wheel loaders and backhoes operated in various environmental conditions in both Europe and North America.
Tracking of various indicators in the oil during the testing and the inspection of selected components from the
machines after the tests showed no problems using this particular bio-oil.
A quasi-single pass test method for fluid power filters
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
E. Urata and K. Suzuki and Y. Kato,
2006,
pp. 95-106,
September 2006
view abstract
This paper discusses methods for measuring and evaluating the filtration performance of hydraulic filters and introduces a quasi-single-pass test method. One well-known method for evaluating filtration characteristics is the multi-pass method. Since the multi-pass test method was specified by the ISO 16889 standard, users believe that the “β (beta)” measured by the standard expresses the filtration characteristic of a filter. However, there have been some suggestions that the beta is not consistent with field experience. Another criticism of the multi-pass test method is that it only deals with steady flow and so is not applicable to practical applications in which unsteady flow is unavoidable. This paper will show that even for steady-state filtration, evaluating filtration performance by the multipass test method is questionable. Instead of the multi-pass test method, we propose a test method that shows a single-pass test condition. Experiments carried out with the proposed method showed that flow rate and contamination levels at the upstream of a filter influence the filtration characteristic.
A Real Time Adaptive Control Algorithm for a VVVF Hydraulic Elevator Using Neural Nets
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
H. Yang and J. Yang and J. Zhang and D. Sha,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 1-5,
November 1997
view abstract
An adaptive algorithm of neural nets with a special perturbation for a real time velocity control system of a VVVF hydraulic elevator has been proposed in this paper. The weight vector of neural network is adaptively adjusted by the LMS with the perturbation, so it is not necessary to know the nonlinear continuous function of the system controlled. The nonlinear velocity control system is considered as the controller output function in an adaptive controller model. The experimental results obtained from the VVVF hydraulic elevator have shown that the neural nets controller using the perturbation algorithm proposed are much stronger in stability and faster in dynamic response compared with the conventional PID controller.
A REDUCED ORDER MODEL FOR A LAMINAR TRANSMISSION LINE FLOW
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
B. Manhartsgruber,
2006, August 2006
view abstract
This paper presents a novel approach towards the input-output oriented modelling of hydraulic transmission lines. If
the Reynolds number is low enough to justify the assumption of laminar flow and if convective terms are negligible, the
governing equations are linear and a very compact description of the input-output behaviour of a transmission line exists
in the frequency domain. For a coupled simulation of networks of transmission lines interacting with other, possibly
nonlinear components such as valves, there are numerous approaches for the approximation of the transcendental transfer
functions arising from the transmission line dynamics by finite dimensional models in the time domain. The proposed
method for the derivation of reduced order models offers a trade-off between the degree of accuracy and the system order.
Important properties like the passivity of the transmission line model and the exact fulfillment of the Joukowsky relation
are guaranteed.
A reduced-order model for a poppet-type relief valve
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
N. D. Manring,
2008,
pp. 199-214,
September 2008
view abstract
In this paper, the dynamics of a poppet-type relief valve are studied for the purposes of generating an accurate reduced order model that may be used in the simulation of hydraulic systems. This study begins by developing a nonlinear model of the valve system including the steady and transient flow forces that act on the poppet. From here, a linearized third order model is produced from which a stability criterion for the system is deduced using the Routh-Hurwitz method. By neglecting the mass of the poppet, a reduced second order model is developed from which the system’s natural frequency and damping ratio are determined. The nonlinear, linearized, and reduced order models are compared using simulation studies and it is shown that the reduced order model correlates well for sufficiently stable systems that are characterized by damping ratios less than 0.718.
A Reliability (Dependability) Analysis and Testing of the Airplane Hydraulic System (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
J. Novák and J. Hlinka,
2006,
pp. 106-114,
Mai 2006
view abstract
The paper deals with reliability requirements of airworthiness regulations on aircraft
hydraulic systems (with a focus on US FAR-23 and European CS-23 regulations). Mentioned
regulations include requirements for the structural design, design of systems, etc. They cover
wide range of airplanes from small sport airplanes to 19-seats transport aircraft. Also options
for predictive reliability analyses and reliability tests are discussed in the paper. Practical
application is expected on small transport airplane (currently in the development). Statistical
estimates from limited tests will be used to validate (at least partially) results of predictive
analyses.
Expected major contribution of the work is selection and practical application of the most
suitable procedures for safety assessment on the field of aircraft hydraulic systems, with a
focus on the small transport aircraft.
A Review of Activities for Automation in Mobile Machines
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
T. Lang and T. Fedde and H.−H. Harms,
2007,
volume 3,
pp. 47-55,
Mai 2007
view abstract
In recent years the use of electronics in mobile hydraulics has grown significantly.
Electronics are the key for the implementation of automated functions in mobile hydraulics to improve the efficiency of the operating processes and to ease the handling of the machine.
Especially at the working hydraulics closed loop controls are in the centre of interest.
The control of several motion drives is a challenge in mobile hydraulics because of the varying load conditions at mobile machines and the dynamic behaviour of the commonly used Load-Sensing systems.
The following paper deals with an review of previous and actual activities for the introduction of automations in mobile hydraulics at the Institute of Agricultural Machinery and Fluid Power. The presentation gives the results of several projects at the institute and picks up newly launched industrial products.
A Robust Hydrostatic Thrust Bearing for Hydrostatic Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
P. Achten and T. van den Brink and G. Vael,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 301-314,
März 2010
view abstract
In axial piston machines, the interface between the barrel and the port plate is one of the most complicated hydrostatic bearings. The gap height is governed by a complex combination of mechanical force and torque balances, which are in the end controlled by elastohydrodynamic and thermal effects. Even small deformations and wear can result in strong variations of the gap height, and consequently can have a significant effect on viscous and non-viscous friction. This paper describes a new design of a bearing geometry, which strongly reduces the effects of deformation and heat transfer and creates a more robust definition of the hydrostatic pressure forces in the sealing gap between the barrels and the port plates. The construction is also applicable for other thrust bearings in hydrostatic machines.
A Self-Tuning Fuzzy Control of an Electro-Hydraulic Fin Position Servo System
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
S. Y. Lee and Y. J. Park and H. S. Cho,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 99-106,
November 1998
view abstract
Electro-hydraulic servo systems have been frequently used in the fin position servo system of a missile because of their high power and good positioning capability. The objective of this paper is to realize a self-tuning fuzzy controller for the position control of an electro-hydraulic fin servo system. In this paper, we propose a new self-tuning fuzzy controller, which can improve the overall performance of the electro-hydraulic fin position servo system. The uniqueness of this self-tuning fuzzy controller is that the performance evaluation of the fin position servo system is carried out in a phase plane mapped to a decision rule table. The effectiveness of this control scheme is verified by comparison with a fixed fuzzy control with initial rules through a series of simulation studies.
A simple model of piston-cylinder gap efficiency in positive-displacement hydraulic pumps and motors
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
K. A. Stelson and F. Wang,
2010,
pp. 417-429,
September 2010
view abstract
This paper describes a simple model of the piston-cylinder gap in positive-displacement hydraulic pumps and motors. Fundamental equations and dimensionless scaling are used to describe flow and mechanical losses and relate these losses to overall pump and motor efficiency. The equations are cast in dimensionless form where it is shown that efficiency depends on three dimensionless groups; the dimensionless viscosity, dimensionless gap height and the fractional displacement. To achieve this simplification, an unconventional definition of dimensionless viscosity is shown to be required. Finally, the dimensionless viscosity that results in the maximum piston-cylinder gap efficiency is derived for both pumping and motoring. Because of the simplicity of the approach it is hoped that it would provide a useful example of one aspect affecting efficiency of hydraulic pumps and motors for both for practicing engineers and students in university fluid power courses.
A Simple Novel Approach to Active Vibration Isolation With Electrohydraulic Actuation
Yisheng Zhang and Andrew Alleyne,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 125-128,
März 2003
view abstract
This paper describes a novel reformulation of a classical active vibration isolation problem, explicitly accounting for the dynamics of the actuator. By utilizing a clever reformulation of the problem rather than the traditional approaches, a very difficult problem can be transformed into a relatively easy one. Subsequently, any reasonable loop closure methodology can be used to achieve the necessary performance. The traditional approaches usually consider a regulation problem, whereas the focus here will be on generating a tracking problem to achieve the same results: reduced transmission of vibration. Experimental results are included to demonstrate the effectiveness and advantages of the proposed problem representation.
A Simulation Study on the Back Thrust of Water Jet
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Yousheng and Z. Yuquan and L. Yinshui and L. Zhuangyun,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 563-568,
April 2005
view abstract
Clear knowledge on the back thrust of water jet is valuable for better design of water jet cutting system and jet propulsion system. In this research, simulation and theoretic analysis are conducted to investigate the back thrust of water jet of different cylindrical nozzles. Effects of pressure, flux as well as dimensions of the nozzle are investigated particularly. The simulation results show that the back thrust has a linear relationship with the product of the nozzle inlet flux and the square root of inlet pressure. And the results also indicate that the length of the nozzle exerts little influence on the thrust, but the nozzle diameter has opposite effect that shows the thrust increases with the nozzle diameter decrease. And the back thrust coefficient decreases with the shortening of the nozzles when l < d0, and it approximates 1.2~1.3 when l ≥d0.
A Simulation Study on the Impact of Material Properties on Piston/Cylinder Lubricating Gap Performance
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
M. Pelosi and M. Ivantysynova,
2010,
volume 1,
pp. 373-386,
Juni 2010
view abstract
The lubricating gaps of axial piston machines represent the main source of energy dissipation. Among them, the
piston/cylinder lubricating gap is one of the most critical interfaces, being a pure hydrodynamic journal bearing, which
requires fulfilling simultaneously a bearing and sealing function under oscillating load conditions. A deep
understanding of the physics characterizing the complex fluid-structure interaction and thermal phenomena taking
place in this lubricating gap is crucial for an effective machine design, allowing an accurate prediction of the gap flow, the load carrying ability and the energy dissipation. The paper presents a unique fully coupled fluid-structure and
thermal multi-body dynamics model for the piston/cylinder interface which considers the simultaneous impact of
mechanical bodies surface elastic deformations and heat transfer phenomena on the non-isothermal gap flow
calculations. In particular, the model considers the squeeze film effect due to the micro-motion of the solid parts and the
change in fluid film thickness due to the elastic deformations caused by the gap fluid pressure and the materials thermal expansion. Since the fluid flow is considered as non-isothermal, the fluid model is also coupled with a heat transfer model of the solid parts predicting the bodies surface temperatures used as a more accurate boundary condition and the bodies temperature distribution used to determine the thermal loading conditions. The effect of the different physical phenomena is discussed and it is shown how thermo-elastohydrodynamic lubrication plays a significant role in this tribological interface. Simulation results are shown for a typical brass-steal pair highlighting how altering material properties of the mechanical bodies would play a dramatic role in lubricating gap performance, influencing due to their characteristics temperature distributions, elastic deformations and ultimately leakage and viscous friction.
A simulation study to reduce noise of compact power-split-drive transmissions
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
R. Klop and K. Williams and D. Dyminski and M. Ivantysynova,
2007,
pp. 83-102,
September 2007
view abstract
The aim of this study is to demonstrate a simulation based approach of reducing noise generation in compact power-split-drive transmissions. A compact output-coupled transmission designed for a passenger car is modeled based on a typical drive cycle for inner-city driving. This study identifies noise sources and discusses various methods of noise reduction techniques in a compact power-split transmission. The influence of valve plate design in regards to noise generation over a complete operating range is the primary focus. This study emphasizes the complexity of optimizing for minimum noise generation over a large operating range.
A STUDY OF GAP FLOW CONDITIONS BETWEEN THE PISTON AND THE CYLINDER OF AN AXIAL PISTON PUMP
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
A. Fredrickson and M. Ivantysynova,
2008,
pp. 273-284,
Juli 2008
view abstract
An EHD model for axial piston machines was compared with a rigid model and with measurement. Both models describe
the micro motion of the piston and solve the Reynolds equation for the resulting gap flow, but the EHD model considers the
surface deformation of the cylinder bore and piston, whereas the rigid model does not. The two models were used to predict
the axial and tangential friction forces exerted on the cylinder of the machine at multiple operating conditions. The results
were compared with friction force measurements obtained from a specially designed pump.
A Study of Pneumatic Pipes Modeling
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
E. Bideaux and S. Scavarda,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 197-205,
November 1998
view abstract
In fluid power system, lines or pipes can have a predominant effect on dynamics. Although many studies have been carried out on hydraulic pipe modeling, there are only a few existing
approaches for such problems in pneumatics. This paper proposes a basic work for modeling of pneumatic pipes. After presenting the stare of the art situation and the nature of this problem, we have proposed two ways of modeling pneumatic pipes. The first one consists of a discretization scheme based on an upwind finite differencing scheme. This method has
advantages but can lead to erroneous results in the case of a predominance of the convection effect when the direction of flow changes rapidly. We propose a method for solving such
difficulties. We also propose a second method which is based on a finite volume approach. This type of model represents the convection effect better and we will prove its robustness through several examples. Before concluding, in order to validate our propositions, we compare experimental trails to the results given by the simulation of the two methods.
A STUDY ON COMPOUND GEAR PUMP
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
L. Zhenhui,
2006,
volume 1,
pp. 197-204,
Juni 2006
view abstract
This paper presents a new gear pump called compound gear pump. Based on the analysis of flow
pulsation, this paper established a mathematical model, with the optimization of the pump. It is shown
that the new pump has a bigger displacement and better flow characteristics.
A STUDY ON TELE-REHABILITATION SHARING SYSTEM FOR WRIST BASED ON INTERNET
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
Z. Xiu and A. Kitagawa,
2006,
volume 2,
pp. 585-594,
Juni 2006
view abstract
This research discusses an Internet-based Tele-rehabilitation system, which is aimed to realize that multiple home-stay
patients in different places can share rehabilitation instruction of one physical therapist at the same time. And after the
introduction of the whole system, the rehabilitation devices developed by Wound-Tube Actuator (WTA) with pneumatic
power are introduced; then the operation method of the whole system with single-master and multi-salve is described;
after that the stability problem of the master-salve system with the variable time-delay which is the biggest problem of
the teleoperation system is described and the control architecture is proposed.
A Study on the Boom Energy Regeneration System for a Hybrid Excavator
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Kang, Byung-il and Oh, Se Boung,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 129-142,
März 2010
view abstract
Recently highlighted hybrid excavators that employ an engine and electric devices as power sources have been studied to reduce energy losses and make the system more efficient through regenerative energy. On an excavator, a lot of energy can be recovered during boom lowering and swing deceleration. This paper presents boom energy regeneration schemes and control methods. After analyzing the experimental data of the conventional excavating mode, two types of regeneration systems were developed to use electric devices as a power source; the stand-alone and the collaborated boom energy
regeneration system. The stand-alone boom energy regeneration system supplies and regenerates the whole power of the boom independently and regardless of the existing hydraulic system. The collaborated system has to be supported by the existing hydraulic system to raise the boom and a certain portion of hydraulic flow is bypassed during boom lowering. Simulation studies of the two systems show that the stand-alone system has higher efficiency than the collaborated system. However, in the component capacity and cost point of view, the collaborated system is advantageous for realization. Further studies on simulation and experimental verifications of the collaborated boom energy regeneration system will be concurrently performed to design an optimal system.
A Study on the Design Parameter of Pressure Control Valve for Continuously Variable Transmission
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J.-S. Jang and Y.-H. Yoon,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 537-542,
April 2005
view abstract
In this paper, pressure control valve (PCV) are investigated by considering the shift dynamics characteristics. However, a highly reliable and inexpensive control system is required for a mid-class passenger car. The control-ability of continuously variable transmission (CVT) system is strongly affected by the performance of pressure control valve from the view part of dynamic response and energy consumption. In this study, we have suggested main design parameters for the optimum design of pressure control valve which plays the most important role in the CVT fluid power system. The mathematical simulation model was derived from the full model for the purpose of analyzing the valve characteristics. The AMESim software has been used for the investigation of valve characteristics. Experiments were performed to confirm the performance of the valve and computations were carried out to ascertain the usefulness of the developed model. The results from computations fairly coincide with those from experiments. The results from experiments and computations show the development process of pressure control valve in the hydraulics system of CVT.
A Study on the Use of Simulation as a Design Tool Applied to a Commercial Proportional Valve Group
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
M. R. Hansen and T. O. Andersen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 606-610,
April 2005
view abstract
This paper examines the use of simulation as a design tool applied to the Sauer-Danfoss proportional valve group PVG32 typically used in mobile hydraulics. A general discussion on the use of simulation in hydraulics design is given and three different studies on simulation applied to the PVG32 are given. The examples include: design of discharge area characteristic of main spool, feasibility study for use in active damping of agricultural tractors, and design of tool point control of an aerial lift.
A Study on Water Hydraulic Unloading Relief Valve
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Yongjun and Z. Hua and Y. Huayong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 213-217,
April 2005
view abstract
Although the use of water is neither new nor innovative, the use of water as a working fluid in hydraulic circuits is receiving an increasing attention by both manufactures and users due to its fire resistance and environmental compatibility.
The water hydraulic components are being developed thoroughly. Materials, machining technology, structures and so on must be examined for whether or not they are compatible with water when the components are designed. The purposed of this paper is to show a water hydraulic unloading relief valve and its principle which is invented by Zhejiang university. From the view of flow control, the method of cavitation resistance of a water hydraulic unloading relief valve are investigated. The computational fluid dynamics approaches are applied to obtain static pressure distributions and cavitation images in the channel of the main stage of the valve with four kinds of structure. These structure consist of one-stage throttle, one-stage with high-pressure induct, two-stage throttle and two-stage throttle with high-pressure induct. The experiments are carried out with different supply pressure, flow rate and the opening on the pilot-operated water hydraulic relief valve. The results show that the method of combined cascading restrictors with high-pressure induct can effectively restrain cavitation.
A Suggestion of Artificial Filter Test Dust
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
E. Urata and K. Tajima and K. Suzuki and T. Suda,
2007,
volume 2,
pp. 203-212,
Mai 2007
view abstract
We made an artificial test dust for a test of fluid power filters because natural sands have some
drawbacks. First of all, particles of test dusts produced from natural sand take irregular shapes and various colours that influence particle size estimation. Second, they are prone to sedimentation because their specific weight is greater than working fluids. Thus, particular characteristics of a natural sand influence measured result of filtration test. Therefore, for reproducibility of filter tests, we are forced to specify the source of the sand as well as its supplier. However, if test dusts are artificially made and their preparation
procedures are specified, we can obtain the following benefits: 1. Everyone in the technological world can produce the test dust with the same quality. 2. Spherical particles are obtained. 3. Particle diameter distribution can be designed. 4. Specific gravity is controlled; sedimentation inherent with a natural dust is avoided. 5. A uniform colour is established. These advantages increase accuracy of filtration experiments
and testing.
However, the problem is whether we can prepare such an artificial dust under reasonable labour and price.
This paper describes our trial for creation of an artificial test dust using a simple apparatus that can be built in
a usual fluid power laboratory. Brief explanation of test dust production The principle we have taken for dust
generation is injection of liquid styrene monomer (LSM) into water with dissolved surfactant. The LSM is extruded through a porous media. The water with dissolved surfactant flows along the surface of the porous media and takes away small portions of LSM; thus small liquid droplets of LSM are formed in the water. Our experimental rig is composed of a cylinder and a piston for LSM extrusion, a tubular porous media made of
sintered bronze, and a water circulating unit. The particles are produced in the following process. Fill the
cylinder with the LSM. Run the pump and circulate the water with the surfactant in the circuit. Then drive the
piston to supply the LSM outside of a sintered bronze porous media tube. In this way the LSM is extruded into the water flowing inside of the porous media tube. The LSM becomes small droplets in water. After extrusion is completed, the water suspending LMS droplets is put on a hot−stirrer and agitated about five hours keeping the temperature 70−80°C. This process polymerises the LMS and the droplets change to polystyrene particles. Result and conclusion Measured result of the produced particle size distribution was similar to those of common natural dust. Observation by an electron microscope proved that the particle shape is spherical. We will show the dimensions and precise procedure of this artificial dust
production. Thus, this paper presents a method to produce the same test dust everywhere in the world. The dust produced in this way will help accurate testing of filtration performance of fluid power filters.
A Survey of Hydraulic Fluid Analysis Methods
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
F. Don Norvelle,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 39-44,
November 1996
view abstract
This paper is intended to provide the reader with a brief overview of the types of analyses that can be used to determine the condition of hydraulic fluids. Several types of contamination are discussed along with their effect on the system and components. Methods of detecting these contaminants are then presented. Finally, recommendations are presented for establishing a fluid analysis program. An appendix is included which lists standards and specifications dealing with hydraulic fluid condition analyses.
A SYSTEMATIC METHODOLOGY FOR OPTIMAL COMPONENT SELECTION OF ELECTROHYDRAULIC SERVOSYSTEMS
E. Papadopoulos and I. Davliakos,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 15-24,
November 2004
view abstract
This paper focuses on optimal hydraulic component selection for electrohydraulic systems used in high performance
servo tasks. Dynamic models of low complexity are proposed that describe the salient dynamics of basic electrohydraulic
equipment. Rigid body equations of motion, the hydraulic dynamics and typical trajectory inputs are used in conjunction
with optimization techniques, to yield an optimal hydraulic servosystem design with respect to a number of
criteria such as cost, weight or power. The optimization procedure employs component databases with real industrial
data, resulting in realizable designs. An example illustrates the developed methodology.
A Systematic Philosophy Consideration on the Fluid Power Driven and Control Technology
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Yongxiang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 1-5,
April 2005
view abstract
In this article the author presents a systematic philosophy consideration on the fluid power driven and control technology. Definite application areas and functions of the technology are described based upon the physical fundamentals of the fluid medium, the functional position of the technology in general engineering systems and the main technical characteristics of the fluid power driven and control technology. Trend predictions on the technology have also been carried out.
A Test Rig for an Adaptive Magneto-Rheological Fluid Bearing and an Analytical Model of its Load Carrying Capacity
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
N. Gstöttenbauer and B. Manhartsgruber and R. Scheidl,
2006,
volume 1,
pp. 129-141,
Juni 2006
view abstract
Magneto-rheological (MR) fluids are suspensions of micron-sized ferromagnetic particles in a non-magnetic carrier fluid. The essential characteristic behaviour is the rapid and reversible transition from the state of a Newtonian-like fluid to the behaviour of a stiff semi-solid by applying a magnetic field of about 0.1-0.4 Tesla. This feature, called the MR-effect, can be understood from the fact that the particles form chain-like structures aligned in field direction. The MR-fluid offers three modes of operation. Either the direct shear motion of two magnetic poles separated by the fluid generates shear forces, or the valve mode restricts the flow through passages. Due to its highly non-linear behaviour, the third mode of operation, the squeeze mode is up to now used for small amplitude vibration damping only. A test rig for the exploration of the MR-fluid behaviour was designed for experimental purposes. Special emphasis was put on the dependence of the MR-fluid response with respect to parameter variations of the applied static magnetic field, the cyclic loading amplitude and frequency values. Thereby attained new perceptions gave reason to design an adaptive magneto-rheological fluid bearing in squeeze mode behaviour for industrial applications. A modification of the existing test rig was accomplished to prove the expected behaviour and benefits of this new concept. The substantial innovation is the rapid control of the radial load carrying capacity using current as control variable. Furthermore, high load carrying capacities at low rotational speed can be accomplished whereby rate dependence is negligible. Particularly for the bearing in squeeze-mode the interrelationship of the radial force and the magnetic flux induction as well as the squeeze gap geometry is of great relevance. For design engineering preferably simple analytical approaches describing the load carrying capacity of such a bearing are of interest and will be discussed in this paper.
A Test-Rig for the Characterisation of Fast Check Valves
Power Transmission and Motion Control - PTMC 2006
A. Plöckinger and B. Manhartsgruber,
2006,
pp. 335-346,
September 2006
view abstract
While the measurement of the dynamic properties of a standard spool valve for directional flow control is a well defined task in the fluid power community, the characterisation of check valves is much less clear. In the first case, the response of the spool position to various inputs like steps or sinusoids is measured. The comparison between the desired spool position (input) and the measured output is shown as a step response plot and/or as a bode diagram in the data sheet. The influence of a flow rate across the metering edges of the valve is often not shown in these figures, yet it is always present due to flow forces acting on the spool. However, the flow forces tend to influence mainly the magnitude of the transfer function between the desired and the actual spool position. The phase lag responsible for stability problems is only marginally affected. Therefore, the interaction between the controlled flow and the spool actuation is often neglected. In the case of a check valve the situation is completely different. The only forces acting on the flow restricting element are the spring load and the forces exerted by the fluid. While it is in principle possible to measure the movement of the flow restricting element there is no demand signal to compare with. In the literature the dynamics of check valves is often characterised by the eigenfrequency of the spring-loaded restricting element not taking into account the interaction with the flow. This paper shows that there is a significant influence of the surrounding hydraulic fluid. Furthermore, details on a test rig and a measurement procedure for the dynamic characterisation of check valves are given.
A TIME ENCODED SIGNAL PROCESSING/NEURAL NETWORK APPROACH TO FAULT CLASSIFICATION OF AN ELECTROHYDRAULIC CONTROL SYSTEM
J. Watton and N. Freebody,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 59-66,
Oktober 2000
view abstract
A fault classification approach is presented which considers the advantages of Time Encoded Signal Processing
(TESP) of dynamic signals combined with the ability of Artificial Neural Networks (ANNs) to classify changes in TESP
codes. This is demonstrated using a new TESP code approach applied to a pressure control system exhibiting both leakage
at the actuator and a servovalve fault. It was found that the use of both pressure transducer voltage and servovalve
drive voltage, when entered into the ANN in a parallel data structure manner, resulted in an excellent fault classification
capability. In addition the inherent classification approach gave very good leakage discrimination for arbitrarily-set, and
low, levels of 0, 2, 4, 6 l/min. A range of 16 different ANNs were investigated and the classification results indicate a
preferred topology for this application.
A Two Regime Orifice Flow Formula for Numerical Simulation
A. Ellman and R. Piche,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 721-724,
view abstract
Because the conventional formula for turbulent orifice flow rate has an infinite derivative when the pressure difference is zero, ODE solvers may fail during numerical simulation of fluid power circuits. To remedy this, a two-regime orifice flow formula is proposed in which an empirical polynomial laminar flow function is used for small pressure differences. The proposed formula has a smooth transition between laminar and turbulent regimes, and its derivative does not have any singularities.
A Unified Force Controller for a Proportional-Injector Direct-Injection Monopropellant-Powered Actuator
Kevin B. Fite and Jason E. Mitchell and Eric J. Barth and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 159-164,
März 2006
view abstract
This paper describes the modeling and control of a proportional-injector direct-injection monopropellant-powered actuator for use in power-autonomous human-scale mobile robots. The development and use of proportional (as opposed to solenoid) injection valves enables a continuous and unified input/output description of the device, and therefore enables the development and implementation of a sliding-mode-type controller for the force control of the proposed actuator, which provides the stability guarantees characteristic of a sliding-mode control approach. Specifically, a three-input, single-output model of the actuation system behavior is developed, which takes a nonlinear non-control-canonical form. In order to implement a nonlinear controller, a constraint structure is developed that effectively renders the system single input, single output, and control canonical, and, thus, of appropriate form for the implementation of a sliding-mode controller. A sliding-mode controller is then developed and experimentally implemented on the proposed actuator. Experimental results demonstrate closed-loop force tracking with a saturation-limited bandwidth of approximately 6 Hz.
Auto-Loopshaping Control of Electro-hydraulic Servo Fatigue Testing Machine
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Chang-chun and L. Xiaodong and Z. Jinying and L. Dejun and S. Jian and L. Zhan ,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 243-246,
April 2005
view abstract
There are so many work conditions for fatigue test to overhead connect line parts with fatigue testing machine. In order to satisfy the requirements of design, a new control scheme is applied. Based on the mathematical model of system, the method is theoretically studied, and then a new controller design idea - Auto-Loopshaping is presented.
Automatic Derivation of Symbolic State Equations for Mechatronic Systems
Proc. 2nd European Nonlinear Oscillations Conference, Sept. 9-13, 1996, Prague
W. Fuchs and R. Kickinger and W. Meindl and R. Scheidl and K. Schlacher,
1996, November 1996
view abstract
A MAPLEV based program system METRONIC is presented which derives state equations for mechatronic systems in a symbolic form. Symbolic versions od state equations are prerequisites for certain analysis methods and for the derivation of control algorithms. By two examples we will demonstrate how symbolic state equations can be automatically nondimensionalised, prepared for perturbation analysis, or how nonlinear control algorithms can be derived automatically.
Automatic Design of Proportional Valve Spools
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
M. R. Hansen and T. O. Andersen,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 475-489,
November 2003
view abstract
The current paper presents an implemented design procedure that automatically generates the
metering geometry of a spool valve based on a desired discharge flow and return pressure
characteristics. The cutter radius as well as the actual paths to be traveled by the cutter are the
design parameters used to compute the discharge area characteristic of the resulting slot
arrangement that in turn is used in a static simulation to evaluate the design. The design
parameters are determined by means of a classical minimization technique, Davidon-Fletcher-
Powell, and the objective function is simply computed as the deviation between actual and
desired discharge flow. The design procedure may either be carried out semi-automatically
with the user supplying an initial design, or it may be done full-automatically with the
program choosing the most promising designs among already existing ones.
Automatic Generation of Simplified Models
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
L. Mikelsons and O. Lenord and H. Ji,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 509-522,
März 2010
view abstract
This paper is concerned with model reduction techniques and their application to real-time simulations of hydromechanical systems. The aim of this work is to minimize the modeling effort by reusing detailed system models in later stages of the system engineering process. Starting point for this consideration is the object-oriented modeling of the physical system using acausal equation-based formalisms (i.e. Modelica™) that lead to symbolic representations of the mathematical model. The presented reduction method allows for the automatic reduction of symbolic DAE systems according to their number of terms and states until a given error bound, or respectively a required cycle time of a defined real-time target, is achieved. The paper describes the ranking strategy and reduction technique involved. Furthermore, the effectiveness of the methodology is demonstrated by a relevant industrial application. A detailed model of a hydromechanical mobile construction machine is derived and subsequently reduced for the purpose of real-time simulation. A physical interpretation of the reduced model is given. The outlook describes future work on remaining deficiencies and the potential for future applications.
Automatic Level Control in Agricultural Machinery
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
B. Winkler and R. Scheidl,
2002, Juli 2002
view abstract
Mainly for rationalization of agricultural work speed of operation and quality requirements are steadily increasing. As a consequence, operational performance characteristics of many tractor implements have to be improved with respect to speed, response time, failure probability and accuracy. In some cases state of the art solutions do not meet this requirements. In particular, mechanical distance devices in grass harvesting machines, such as simple wheels, rollers or vats do not fit to operating speeds required in near future. The method of resolution presented in this paper is an automatic level control unit of the pick-up device of a harvester. The presented concept replacing common distance devices is able to fulfil the mentioned requirements of increasing speed of operation and avoidance of damage. The most challenging aims to be achieved was scanning the very rough agricultural working surface, realizing short reaction times by means of hydraulic actuators and to develop a proper control unit. Besides the technical realization of these functions it is essential to keep costs low according to limitations in agricultural machinery.
AUTOMATIC RECOGNITION OF HYDRAULIC COMPONENT SYMBOLS IN TECHNICAL DRAWINGS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Ciężobka,
2008,
pp. 365-370,
Juli 2008
view abstract
This report presents the results of the research on the ways of detecting hydraulic objects such us pumps, valves with
flow control, return valves, pressure valves, valve and slide controlled distributors, proportional elements and cartridge
hydraulics, present on technical drawings prepared using the AutoCAD software. The recognition as well as precise
description of the objects will find its way to business applications, where the appropriate presentation of the given
project can provide an explanation and assist comprehension to both laymen as well as company directors and other
people responsible for marketing, thus increasing the chances for good sales for such products.
AUTOMATION OF A MECHANICAL CHILDBIRTH SIMULATOR USING ELECTROPNEUMATIC COMPONENTS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
O. Olaby and X. Brun and T. Redarce and R. Moreau and O. Dupuis,
2006,
volume 2,
pp. 543-555,
Juni 2006
view abstract
This paper presents some new automatic procedures for a mechanical childbirth simulator BirthSIM. BirthSIM is a
complete training system for simulating labor during childbirth. This simulator also tests new techniques for obstetric
practice. BirthSIM consists of a dynamic pelvic model which simulates a pregnant human female and in which the
newborn’s head is located in the vaginal canal. The newborn’s head is connected to a linear pneumatic actuator driven
by two five-port proportional valves.
A global characterization of the static flow stage of the electropneumatic proportional valve Festo has been carried out.
An analytical model has been obtained using characteristic 3D graphs where a set of curves gives the output mass flow
rate as a function of the electrical input for different values of the pressure ratio (upstream/downstream). This model is
useful for carrying out the synthesis of linear control laws for feedback control in position, velocity or force tracking
according to the desired trajectories. The medical conditions are translated into an automation problem by the
synthesis of input trajectories for the electropneumatic system. Position feedback control is necessary to position the
head of the newborn on a horizontal axis. Also, position or force control is important in order to produce the movement
of the head, the mother’s natural contractions and the mother’s pushing action.
In this study some control procedures has been proposed. Different childbirth cases can be simulated by the
electropneumatic system. The validity of the proposed control method for simulating childbirth modes has been
evaluated by means of experiments with an expert obstetrician.
Automotive Design for Electro−Hydraulic Proportional Valves in Mobile Applications
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
H. Geis and J. Krallmann and M. Lutz,
2007,
volume 2,
pp. 193-202,
Mai 2007
view abstract
The developments in the field of mobile working machines during the last years were characterised by a continuing trend to applications with a higher complexity, progressive
processes of automation and uprated requirements on ergonomics and efficiency.
To give consideration to the risen demands, the OEMs are using electro-hydraulic valves to an increasing degree. Especially because of the increasing automation in the use of electro-hydraulic applications there is a need of high precision in the range of micro controlling of the actuators, repeat accuracy, hysteresis and valve-to-valve accuracy. By designing the solenoids in a compact construction, the preciseness of the valves can be increased significantly. Due to the fixed assembly of solenoid and hydraulic part this valves have less variability than systems with removable coils.
The paper shows the advantages and strengths of compact electro-hydraulic valves and shows possibilities to ensure the variability, which is necessary for applications in
mobile hydraulics. Because of the design of defined interfaces between electrical and hydraulic part of the valve it is feasible to build up different types of valves from a
modular system. Beside valves with different working pressures it is possible to realise valves with different volume flows as well.
Autonomous Cleaning Robot Working in Unstructured Environment
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Liu and S. Zhu and Y. Liu and Z. Pang and F. Zhao,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 831-835,
April 2005
view abstract
This paper describes a delicately designed autonomous cleaning robot (ACR) working in unstructured environment without prior knowledge of the environment and global self-localization ability. To do so, we first discuss the state-of-art, the key technique and the open problems of the research on ACR system, then focus on the sensor-based navigation, the intelligent behavior and the task-based working of our HSR2000. Although global self-localization and accurate environment modeling still remain unsolved in the research on mobile robots, experiments show that HSR2000 can effectively learn the environment, cutely avoid obstacles, automatically recharge itself and intelligently plan its cleaning strategy by taking advantage of its local self-localization ability.
A Validated Modular Model for Hydraulic Actuation in a Pushbelt Continuously Variable Transmission
Stan van der Meulen and Rokus van Iperen and Bram de Jager and Frans Veldpaus and Francis van der Sluis and Maarten Steinbuch,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Juli 2011
view abstract
A reduction in the fuel consumption of a passenger car with a pushbelt continuously variable transmission (CVT) can be established via optimization of the hydraulic actuation system. This requires a model of the dynamic characteristics with low complexity and high accuracy, e.g., for closed-loop control design, for closed-loop simulation, and for optimization of design parameters. The hydraulic actuation system includes a large number of hydraulic components and a model of the dynamic characteristics is scarce, which is caused by the complexity, the nonlinearity, and the necessity of a large number of physical parameters that are uncertain or unknown. In this paper, a modular model for the hydraulic actuation system on the basis of first principles is constructed and validated, which is characterized by a relatively low complexity and a reasonably high accuracy. A modular approach is pursued with respect to the first principles models of the hydraulic components, i.e., a hydraulic pump, spool valves, proportional solenoid valves, channels, and hydraulic cylinders, which reduces complexity and improves transparency. The model parameters are either directly provided, directly measured, or identified. The model of the hydraulic actuation system is composed of the models of the hydraulic components and is experimentally validated by means of measurements that are obtained from a production pushbelt CVT. Several experiment types are considered. The correspondence between the measured and simulated responses is fairly good.
A Variable-Speed Pump-Controlled Hydraulic Servo System for a Novel Pitch Control System of Wind Turbines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
M.-H. Chiang and Y.-N. Chen and H.-T. Lin and Y.-Y. Chang,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 405-416,
März 2010
view abstract
The paper aims to develop a novel pitch control system of a large wind turbines driven by variable-speed pump-controlled hydraulic servo system. First, the nonlinear mathematic models of a 2MW wind turbine, including aerodynamic of blade, hydraulic pitch control system, gear box, generator and yaw system…etc., are derived in detail and solved by MATLAB/SIMULINK for realizing nonlinear dynamic simulation of the overall wind turbine systems. Next, the full-scale test rig of the hydraulic pitch control system of wind turbine blades, including a novel mechanism of pitch control, a variable-speed pump-controlled hydraulic servo system, a disturbance system and a PC-Based control system, were designed and set up. The variable-speed pump-controlled hydraulic servo system contains an AC servo motor and a constant displacement hydraulic piston pump. Through the simulations of the overall wind turbine system, the pitch angle of the blades and the resultant load torque of the blade under the random input of wind speed can be solved and given to the test rig of the hydraulic pitch control system for realizing the pitch control experimentally, and thus the hardware in the loop analysis can be implemented for the large wind turbine. Finally, the developed variable-speed pump-controlled hydraulic servo system for the path tracking control of the pitch control of the wind turbines has been realized and verified by both simulations and practical experiments in the full-scale test rig.
A Visco-Elasto-Plastic Material Law for Magneto-Rheological Liquids
Proceedings of the 2nd International Workshop on Computer Software for Design, Analysis and Control of Fluid Power Systems
B. Winkler and B. Manhartsgruber and R. Scheidl,
2001,
pp. 175-182,
view abstract
Magneto-rheologic (MR) liquids are fluids, whose rheologic behaviour can be changed by the attachment and variation of magnetic fields. Within a few milliseconds the internal “friction behaviour” of the MR liquid can be changed continuously over a large scale.
At the micromechanical level, MR fluids feature a complicated behaviour. For example, the spatial distribution of the fluid viscosity depends on the magnetic field density which in turn is influenced by the position and the spatial concentration of the particles. Existing work [1] considers the positioning behaviour of individual particles depending on the characteristics of the carrier medium and the magnetic vector field. Available micromechanical models are derived under the assumption of spherical particles sharing the same diameter. These models can accurately predict the behaviour of MR-fluids, yet are not suitable for use in macroscopic simulations since the model complexity is far too high. Simulations using these types of models would require today’s fastest computers and a lot of CPU-time.
As a result of this paper, we propose the possibilities of simulating MR-fluid-based hydraulic systems using the finite element program ABAQUS and existing (not MR-fluid specific) material models. In particular this method should also be able to describe the behaviour of the medium in the squeeze mode if we can expect isotropic material behaviour.
This paper shows that the squeezing mode is poorly understood compared to the shear and valve mode, therefore, this operational case represents a special challenge and offers most space for new further developments and basic scientific work.
To verify our calculations we build up some experimental setups to measure the behaviour of MR-fluids in all three possible modes (direct shear mode, valve mode and squeeze mode).
Axial Clearance Compensation in Gear Displacement Machines
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
S. Bednarczyk and J. Stryczek ,
2004,
pp. 25-32,
Juni 2004
view abstract
In the paper, two ways of realizing axial clearance compensation have been described: with the use of
slidable compensation plates as well as with the use of deformable compensation plates. They have been
compared to each other and the possible applications have been enumerated. Either of the modes of the
axial clearance compensation has been verified in a different way. The axial clearance compensation
realized by means of the slidable compensation plates has been verified experimentally and the efficiency
of a gerotor pump has been determined. The efficiency characteristics have been provided. The axial
clearance compensation realized as the effect of elastic straining of the compensation plates has been
numerically verified on the example of the satellite low-speed motor. The results of the numerical
simulation of deformations of the motor compensation plates have also been provided.
Axial clearance compensation in the gerotor pump
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
S. Bednarczyk and J. Stryczek,
2008,
pp. 152-159,
September 2008
view abstract
Design and operation principle of the gerotor pump has been discussed in the article. A mathematical model of volumetric losses in the axial clearance of the gerotor pump has been presented. Basic geometrical parameters of the pump, which influence the losses have been specified. The result of the analysis is a statement that the pump’s bodies axial direction deformations determine the volumetric losses. Therefore, application of the axial clearance compensation has been suggested. Presented have been the theoretical bases of the axial clearance compensation as well as the design of the pump featuring the axial clearance compensation. Findings of the research on the axial clearance compensation gerotor pump have been presented.
Axial Piston Pump and -Motor Optimization by Means of CFD
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
M. Heinz and R. Fidler and W. Dittrich and M. Krätschmer,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 605-615,
März 2010
view abstract
The paper shows a procedural method to simulate the three-dimensional fluid flow behavior in piston pumps and -motors by means of CFD. The piston motion is taken into account by using a deforming mesh algorithm as well as the compressibility of the hydraulic fluid and cavitations. Additionally semiautomatic procedures to optimize the port timing were implemented. As in the beginning the piston motion was described by dedicated profiles generated from theoretical calculations in the meantime it is controlled by coupling the CFD-model with one-dimensional simulations which can take into account additionally effects like piston shoe clearance or swash plate oscillation. The use of this procedure in several projects have shown that it is a useful method to optimize piston pumps and -motors with respect to pressure ripple and cavitations as well as to investigate failure scenarios by coupling to structural dynamics simulation.
Backstepping sliding-mode control for a pneumatic control system
C.-H. Lu and Y.-R. Hwang and Y.-T. Shen,
In Proc. of the Institution of Mechanical Engineers Part I, Journal of Systems and Control Engineering,
2010,
volume 224,
pp. 763-770,
view abstract
In general, air motors have been applied for automation in industry. There are many kinds of air motors used in automation equipment, such as vane air motors, piston air motors, etc. The advantage of the piston air motor is that it is able to provide larger torque at low speed the air vane motors. The aim of the present study was to analyse the behaviour of such a motor, a radial piston air motor mounted on a ball screw table, and to accomplish accurate desired positioning utilizing a backstepping sliding-mode controller. Variation due to compressibility of the air and friction in the mechanism make the overall system non-linear Two methods were applied to overcome the chattering phenomenon and control the system: the proportional-integral-derivative controller and the backstepping sliding-mode controller. Experimental results showed that the proposed backstepping sliding-mode controller apparently suppresses overshoot and provides accurate positioning performance.
Basic Characteristics of a Silicon Outer Fence Mold Actuator with Human Compatibility
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
Y. Hayakawa and M. Aichi and K. Morishita,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 595-602,
November 2003
view abstract
In this paper, we propose a new type of soft actuator (Pneumatic Silicon Outer Fence Mold
Actuator) that sponge is covered with silicon rubber. Since the stiffness of the actuator is
controlled by pressure in sponge chamber, it is possible to realize a soft mechanism by using
pressure compressibility. In this paper, the structure of the proposed actuator is explained.
Furthermore, it is clarified that the characteristics of the actuator are influenced by the number
of sponge layer and sponge materials. Moreover, we propose a new structure that the number
of outside layer is one and the inside layer has two layers whose one side layer is clipped.
From some experimental results, the differences of these actuators are cleared.
Basic Problems in Fast Hydraulic Switching Valve Technology
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Hangzhou, China
R. Scheidl and B. Steiner and B. Winkler and G. Mikota,
2005,
pp. 53-57,
April 2005
view abstract
Fast and high flow rate switching valves are an upcoming research topic in hydraulics. Requirements for such valves stem from novel fast actuation systems, from emergency handling devices, or from switching control hydraulic systems. New design concepts for such valves are necessary to achieve high flow rates with light weight spools and with short strokes. A basic feature of such valve concepts is to provide multiple metering edges. Inertia not only of the spool but also of the armature of the solenoid for the valves actuation and of eventual intermediate gears are relevant and have to be minimized to reduce the effort of the actuator. Solenoids with a flat armature seem to be the best fitting magnetic actuator type for fast switching. Their force characteristics provides high forces only for small armature strokes. This has to be compensated by a properly tuned gear and repelling spring. Spools with tiny land shapes may cause spool sticking problems which can be prohibited by a proper spool and sleeve design. Fast switching has to be accompanied by measures to avoid harmful pressure oscillations, cavitation, and too high flow rate peaks. Such measures interact with the valve design.
Basics for the Energy Efficient Control of Hydraulic Drives by Switching Techniques
Proceedings of the Third Conference on Mechatronics and Robotics
R. Scheidl and D. Schindler and G. Riha and W. Leitner,
Teubner,
ed. Lückel, J.,
1995,
pp. 118-131,
Oktober 1995
Basics for the Energy Efficient Control of Hydraulic Drives by Switching Techniques
Proceedings of the 3rd Conference on Mechatronics and Robotics, Oct. 4-6, Paderborn, Germany
ISBN: 3-519-02625-2,
W. Leitner and G. Riha and R. Scheidl and D. Schindler,
Teubner, Stuttgart,
ed. J. Lückel,
1995,
pp. 118-131,
März 1995
view abstract
Hydraulic drives currently are under strong pressure by the upcoming electric servo-drives. A main reason for this is the poor energy efficiency of many hydraulic drive systems. Switching techniques which are state of the art for electric drives are now also considered for application in hydraulics. This paper reports about a new principle of switching control of hydrostatic drives which is based on periodic wave propagation in a so called resonator. The need for such a resonator is demonstrated by some simple mechanical arguments first. Then a mathematical model in form of a damped wave equation is used to assess its basic performance characteristics and to derive criteria for optimum design. This system turns out to be a pressure converter which controls the output pressure by the pulse-width of the periodic switching between high and low pressure line. Further features to improve the system are described and discussed.
BEARING LOAD ON CIRCULAR SLIPPERS: HYDRODYNAMIC AND HYDROSTATIC ASPECTS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
G. Carbone and L. Soria,
2002, Juli 2002
view abstract
Slippers sliding on the swash plate of axial piston hydraulic pumps are loaded by a total bearing force on one side
due to the oil flow leaking from the cylinder, that has hydrostatic nature, on the other due to relative motion between
slippers and plate that produces an hydrodynamic kind of lift. In the paper, a circular slipper of geometry commonly
adopted in axial piston pumps is considered sliding on a plane in a straight direction. By a restrictor hole, made at
slipper centre, a mass flow is thought injected between the two members of the couple. By using the Reynolds equation,
pressure distribution is evaluated, once injected flow pressure, slipper-plane relative velocity and slipper slope are fixed.
Fluid-slipper interaction is thoroughly described for the considered geometry, showing how hydrodynamic effect,
related to relative motion, modifies pure hydrostatic pressure distribution and slipper bearing behaviours. Generally,
indeed, the effects due to slipper-plate relative motion are not considered when bearing force is evaluated. In the paper
it’s even shown how, in some cases, sliding motion could produce cavitation under the slipper. Designing
considerations are, then, carried out for evaluating the optimal load-carrying capacity, avoiding that cavitation takes
place. Future developments of the model will include the influence of the actual curved path of the slippers with respect to the swash plate.
Behaviour of MR fluids in squeeze mode
S. L. Vieira and C. Ciocanel and P. Kulkarni and A. Agrawal and N. Naganathan,
In International Journal of Vehicle Design,
2003,
volume Vol. 33, No.1/2/3,
pp. 36 - 49,
view abstract
The behaviour of three types of magnetorheological fluids under squeeze mode was investigated. A special device was designed and fabricated to perform these experiments which were carried out on an Instron Multiaxial Testing Machine. The hysteresis loops of the MR fluids were studied for different intensities of magnetic field, frequency, strain amplitude and angular amplitude. The results showed that the damping force and the area of the hysteresis loop of MR fluids increase with the magnetic field (or electric current i) and displacement amplitude (x0). Changes to the frequency (f) produced different behaviour of the various MR fluids. The peak compressive force was found to increase with the increase in number of cycles (N).
Benefit of the Asymmetrical Half Bridge on Proportional Valve Electronic Control
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
M. Ruggeri and S. Gardenghi,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 419-430,
März 2010
view abstract
Electronically controlled proportional valves are widely used in hydraulic controls both in mobile and industrial applications. Standards for earthmoving machines and for agricultural machines are considered in order to increase safety in mobile applications. In order to increase safety, the classic proportional valves control method is modified. A double control using both high side and low side driver in "asymmetrical half bridge" configuration is used. The solution increases valve control performance: by actuating a PWM control simultaneously in both drivers, the electric coil charge and discharge time are strongly reduced and the electrical effects due to continuous switch of electrical power increase the differential voltage on coil terminals, allowing current recirculation from power source. A simulation is performed and a real control stage is designed, a board is realized and tested both on bench for electric performance evaluation and on a real valve, comparing performance and verifying stage safety.
Big power hydraulic central loading system on board product and chemical tankers
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
A. Banaszek,
2006,
pp. 52-59,
Mai 2006
view abstract
The paper presents a big power hydraulic central loading system mounted on board
modern product and chemical tankers. The concept of typical structure with main parts of
a/m systems are described. High reliability, durability and elasticity of hydraulic drive and
control system in action on board tankers, where is dangerous and explosion area and
important is the safety status, are shown. The problems with powering the so great number of
hydraulic big power devices , especially with start-up the system and long line effect in main
supply lines, are presented. Remote control of hydraulic drives cargo pumps are discussed.
Some examples of solutions on board product and chemical tankers built in Szczecińska
Shipyard are presented. As summary , advantages and disadvantages a/m systems are given.
Biogenous Hydraulic Fluids - Influences of Operations on the Filterability
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
H. Karl and T. Fischer,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 117-126,
März 2010
view abstract
Biogenous hydraulic fluids are used in environmentally sensitive applications because of their environmentally relevant properties/characteristics. The potential to save energy led to a reassessment and gradual promotion of their use in industrial hydraulic systems. Mostly, highly efficient filter materials are installed to meet the high cleanliness standards of these systems. Therefore a good filterability of the hydraulic fluid is needed. This article is supposed to show the results of filterability tests according to DIN ISO 13357/2. Data of biogenous fresh and used oils are presented in comparison to the data of mineral oils.
Biohydraulics − True Alternatives
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
M. Lämsä and K. Kosonen,
2007,
volume 2,
pp. 361-370,
Mai 2007
view abstract
Biohydraulic fluids today have already their third generation raw materials developed. How this huge development has been possible in only two decades is demonstrated. As well the latest laboratory and field test results from longlife, EU Ecolabel approved biohydraulic oils are shown. Also the development work of additives in biolubricants is touched. A testrig solution between laboratory and real life is demonstrated.
Bond Graph Based Approach to Passive Teleoperation of a Hydraulic Backhoe
Kailash Krishnaswamy and Perry Y. Li,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 176-185 ,
März 2006
view abstract
Human operated, hydraulic actuated machines are widely used in many high-power applications. Improving productivity, safety and task quality (e.g., haptic feedback in a teleoperated scenario) has been the focus of past research. For robotic systems that interact with the physical environments, passivity is a useful property for ensuring safety and interaction stability. While passivity is a well utilized concept in electromechanical robotic systems, investigation of electrohydraulic control systems that enforce this passivity property are rare. This paper proposes and experimentally demonstrates a teleoperation control algorithm that renders a hydraulic backhoe/force feedback joystick system as a two-port, coordinated, passive machine. By fully accounting for the fluid compressibility, inertia dynamics and nonlinearity, coordination performance is much improved over a previous scheme in which the coordination control approximates the hydraulic system by its kinematic behavior. This is accomplished by a novel bond graph based three step design methodology: (1) energetically invariant transformation of the system into a pair of "shape" and "locked" subsystems; (2) inversion of the shape system bond graph to derive the coordination control law; (3) use of the locked system bond graph to derive an appropriate control law to achieve a target locked system dynamics while ensuring the passivity property of the coordinated system. The proposed passive control law has been experimentally verified for its bilateral energy transfer ability and performance enhancements.
Bond Graph Modeling and Simulation of Stick-slip Characteristics of a Pneumatic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
B. Zhang and H. Cheng and Y. Ma and G. Peng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 569-572,
April 2005
view abstract
Pneumatic cylinders can not usually achieve steady motion in low speed driving. In this paper, the dynamic model of a pneumatic cylinder system is built by using bond graph method. Bond graphs are extended to deal with non-linearities and multiports in the form of equations by using the language SIDOPS+. Simulations are carried out with different working parameters such as the effective area of the outlet speed control valve and load mass. Finally, the influence of the parameters is derived by running multiple simulations.
Bosch Rexroth Pneumatic System for Automation: Easy-2-Combine (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
T. Bořril,
2006,
pp. 181-185,
Mai 2006
view abstract
Directly combinable individual components simplify handling tasks with small
parts. Providing customers with modular solutions for common handling processes is the
central idea of the new Easy-2-Combine automation system.
Easy-2-Combine is the solution for multi-axis automation tasks with individual
components that can be combined in simple, time-saving assembly steps. This means that the
most common applications in assembly technology can now be done with standardized
interfaces. Centering elements are used for interlocking mounting and connections for
sensors and the air supply are provided at several positions throughout the system, making
complicated and expensive connection kits unnecessary. Rexroth has Easy-2-Combine
components that can perform linear movements, pneumatically driven rotation movements, as
well as gripper functions. Connection kits to flexibly assemble additional components will
also remain in the Rexroth program. As a result of all this, the system Easy-2-Combine is
already equipped for expansion. Rexroth's goal is to integrate additional components and
sizes in the system Easy-2-Combine for handling technology.
Brake System Modeling for Simulation and Control
J. C. Gerdes and J. K. Hedrick,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 496-503,
September 1999
view abstract
This paper presents reduced-order models of brake system dynamics derived from a physical modeling perspective. The vacuum booster model combines a static control valve with dynamic air flows, resulting in the ability to easily reproduce both static hysteresis effects and rapid transients. Following the assumption of incompressible flow, a four-state model of the brake hydraulics is presented and, subsequently, reduced to one or two states for certain applications. Experimental results support the simplifying assumptions made during the modeling process by demonstrating better agreement with the response from pedal force to brake pressure than previously displayed in the literature. These models are intended for use in the design and analysis of vehicle control systems and the evaluation of driver/vehicle interactions through dynamic simulation.
Bubble Elimination Device in Hydraulic Systems
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
R. Suzuki and Y. Tanaka and S. Yokota,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 131-135,
November 1997
view abstract
Bubbles in working fluids have much influence on the performance of hydraulic systems and cause some troubles. In this paper, the performance of the developed bubble elimination device concerning the effect of reducing the oil temperature rise is experimentally investigated. From a view point of energy balance in hydraulic systems, a simple mathematical model is proposed and validity of the model is studied.
BUBBLE ELIMINATION FOR HYDRAULIC SYSTEMS - NEW DESIGN OF HYDRAULIC SYSTEM FOR ENVIRONMENTAL COMPATIBILITY
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
K. Nagaishi and Y. Tanaka and R. Suzuki,
2008,
pp. 254-262,
Juli 2008
view abstract
In view point of environmental compatibility, energy saving, cost saving, high performance and high efficiency, one
trend in fluid power systems is to be designed in a more compact fashion and requiring less fluid in the reservoir. Air
entrainment in working fluids have greatly detrimental effects on function and lifetime of the fluid power components
and systems. Our project research supporter, Suzuki, R. has developed a newly device using swirl flow for bubble
elimination capable of eliminating bubbles and of decreasing dissolved gases. In this research project, we focus on the
technical issue for the air bubbles and aging behaviour of hydraulic oils with various conditions by using of the air
bubble removal device. To investigate processes of the oil degradation, a colour and a total acid number are selected as
analytical items and their two procedures. The test results show clearly that the air bubbles accelerate oil degradation
and shortens the life of the oil. The new design of hydraulic system including the bubble eliminator is necessary for
environmental compatibility of fluid power systems.
CAD of Hydraulic Manifold Blocks Using an Object-oriented Approach
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
P. K. Wong and C. W. Chuen and T. P. Leung,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 183-189,
November 1997
view abstract
In a hydraulic power system, the manifold blocks are usually tailor-made. Computer-aided design of these manifold blocks will facilitate the production
of these systems. An object-oriented approach in the design of these blocks has advantages that modifications of the component physical dimensions can easily be incorporated into the scheme without difficulties.
An object-oriented model to represent the behaviour and the design knowledge of hydraulic power circuits and components is used in this design methodology. The class reconstruction principle enables the class structures of fluid power sub-circuits and components to be defined and expanded in
a rigorous manner. With the aid of object-oriented modelling philosophy, it is extended to manifold block design, which can be viewed both as an object placing problem and as a routing-design problem. In order to provide a
computer-aided engineering solution to these problems, some design rules and algorithms have been proposed and implemented in designing hydraulic manifold blocks. This approach can be used to construct a 3D path
connection algorithm for manifold block design and to support many other design activities.
CALCULATION METHOD FOR THERMAL-HYDRAULIC SYSTEM SIMULATION
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
L. Chenggong and J. Zongxia,
2006, August 2006
view abstract
This paper presents the fundamental approaches of modeling thermal-hydraulic component briefly. A set of lumped
parameter mathematical models are developed which are based on conservation of mass and energy. Subsequently the
connection rule for basic thermal-hydraulic components and the method to automatically generate the complete thermal-
hydraulic system model are put forward. The integration methods for solving the cross-coupling thermal-hydraulic
equations are also discussed for a position-controlled thermal-hydraulic system. Simulation results show the interaction
between pressure and temperature. The simplified representations of thermal-hydraulic differential equations are also
proposed in the paper which can reduce simulation time. The validity of the simplified representations is judged by
simulation.
Calculation of the energy efficiency of a modern hydraulic injection moulding machine
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
J. Weingart and S. Helduser,
2006,
pp. 3-14,
September 2006
view abstract
The paper deals with the energetic behaviour of hydraulic plants. A concept is introduced whereby one can calculate the energy efficiency of hydraulic systems right whilst the conception and dimensioning phase. The quality of the calculations is documented by the comparison with an experimental energy measured hydraulic system, in this case a injection moulding machine.
Calculation on the Critical Back Pressure of Pneumatic Ejector Circuit
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
Z. Guo and X. Li and X. Li and T. Kagawa,
2010,
volume 2,
pp. 741-748,
Juni 2010
view abstract
Ejector is one of the most important vacuum sources in pneumatic systems. When it is applied in pneumatic circuit, the
suction flow rate is influenced by the back pressure of exhaust port. While the back pressure increases, the suction flow
rate remains constant firstly and then decreases once the back pressure is above the critical value. Therefore, it is
important to know the critical back pressure value for designing such circuit. The critical back pressure is calculated in
this paper on basis of one dimensional fluid model of the ejector. For 5 types of ejector, the calculation result is
compared with the experimental data. It is verified that the calculation approach can provide reference to the design of
pneumatic ejector circuits. The back pressure of the ejector applications is recommended to be controlled below the
critical value for the best performance of suction effect.
CASCADE NONLINEAR CONTROL OF PNEUMATIC ACTUATORS WITH APPLICATION TO THE AEROMOVEL TRANSPORT SYSTEM
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Sobczyk and J. Britto and E. Perondi,
2008,
pp. 198-208,
Juli 2008
view abstract
This paper describes a nonlinear control strategy to be applied to a class of pneumatic positioning systems. The
operation principle of such systems is presented, and the elaboration of their mathematical model is outlined. The
proposed controller is based on the cascade methodology, which consists of dividing the whole system model into two
subsystems - mechanical and pneumatic – so that different control structures can be applied to each one. The properties
of the proposed controller are illustrated with an application to the Aeromovel Transport System, which is a nonconventional
urban transport vehicle that runs above rails and is propelled by the pressurized air inside of an elevated
guide. Also, it is provided a description of the current developments in the research of the proposed control system,
which are focused on designing an adaptive friction compensator so that the effectiveness of that controller could be
enhanced when applied to small robotic actuators. From the control algorithm standpoint, the Aeromovel is treated as
a large scale actuator of the same general class as the small ones. Simulation results illustrate the expected
performance of the Aeromovel system when controlled by means of the proposed scheme.
CASPAR Based Slipper Performance Prediction in Axial Piston Pumps
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
C. Huang,
2004,
pp. 229-238,
Juni 2004
view abstract
This paper introduces a new method to predict the dynamic performance of slippers in axial piston pumps.
For the first time also surface deformation of the solid structure of the slipper and the swash plate caused
by the dynamic pressure fieled in the gap are taken into account. The paper shows that the
elastohydrodynamic effect, i.e. the interaction effect between fluid dynamic and surface deformation leads
to different gap flow parameters compared to the rigid model. The program Caspar (Calculation of Swash
plate type axial piston pump and motor) has been modified to allow the appropriate model extension. In
this paper, non-isothermal laminar flow is modled to calculate gap flow and viscous friction as result of
dynamic pressure field and velocity distributiones between slipper and swash plate. in the gap. The lift and
tilt behaviour of slipper is calculated by comparing the balance between all external forces exerted on the
slipper and load bearing capacity of the lubricating film for each time step.
Cavitation Driven Impact in a Hydraulic Piston Pump
Proceedings of DETC'97, ASME Design Engineering Technical Conferences, Sept. 14-17, 1997, Sacramento, California
B. Manhartsgruber and R. Scheidl,
1997, September 1997
view abstract
The occurrence of cavitation in a huge hydraulic supply system of a rolling mill which caused a severe defect in an axial piston pump is investigatet by a mathematical model of the complex suction system. It comprises wave propagation in pipes and hoses, a detailed model of the pump including each of its nine cylinders, cavitation therein, the charge and discharge processes of these cylinders with the intake duct, and several accessories influencing the hydraulic processes. Results obtained by this model are compared with on-site experiments. Countermeasures which have been proposed are evaluated by our model and their practical examination is reported. Due to the strong nonlinearity of cavitation the dynamical system shows two attracting limit sets, one with and one without cavitation. The operating conditions of the original supply system cause startup conditions which do not lie in the basin of attraction of the non-cavitating attractor.
Cavitation Driven Impact in a Hydraulic Piston Pump. - A Theoretical and Experimental Investigation.
Proceedings of ASME Design Engineering Technical Conferences, September 14-17, 1997, Sacramento
B. Manhartsgruber and R. Scheidl,
1997, September 1997
CDIO-CONCEPT FOR ENGINERING EDUCATION IN FLUID POWER, MOTION CONTROL AND MECHATRONIC DESIGN
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
Finn Conrad and T. O. Andersen and M. R. Hansen and T. Sørensen,
2006, August 2006
view abstract
The paper presents significant Danish experiment results of a developed CDIO-Concept and approach for active and integrated learning in today’s engineering education of MSc Degree students, and research results from using IT-Tools for CAE/CAD and dynamic modelling, simulation, analysis, and design of mechatronics solutions with fluid power actuators for motion control of machines and robots. The idea of CDIO-Concept is to take care of that the students are learning by doing and learning while doing when the students are active to generate new products and solutions by going through the phases from to Conceive, Design, Implement and Operate related to en product design by them self in competition with others. The idea is based on the Danish implementation of a CDIO-Concept. A curriculum at Aalborg University, and Technical University of Denmark, offers courses for Motion Control, Fluid Power within mechatronics design, and advantages as well as challenges are identified and discussed. An IT-tool concept for modelling, simulation and design of mechatronic products and systems is proposed.
Centrifugal Compressor Dynamics and Software System for Surge Control
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
J. Nevrlý and J. Marek and L. Vargovčík and J. Oldřich,
2008,
pp. 33-40,
September 2008
view abstract
Centrifugal compressor surge dynamics and software system for centrifugal compressors surge control inside the safe working area but in the near proximity of control (or backup- or surge) line based upon ČKD Nové Energo research are described in the paper.
At small mass flows the performance of a compression system is limited by the occurrence aerodynamic flow instabilities, which can lead to catastrophic failure of the compressor due to mechanical and thermal loads. Recent innovations in control technology have made it possible to supply surge control systems which are capable of coping with rapid flow fluctuations and process gas variations.
A compression system model developed by Greitzer is mentioned in the paper. The oscillations in the system are modeled in a manner analogous to those in a Helmholtz resonator. It is supposed that all the kinetic energy of the oscillations is associated with the motion of the fluid in the compressor and ducts.
The suggested system of radial compressors surge control consists of parts of
- measuring of technical data of the compressor (compressor operating point)
- computation of a distance of the operating point from the “anti-surge” action
- control parameter setting
- setting of approximation parameters for calculation of the “anti surge” action (input of all approximation parameters of approximating polynomials and correcting relations)
- computation of a working space of the compressor (a row of arranged couples – values of flow and pressure in the compressor outlet)
- computation of a working characteristic of the compressor (a row of arranged couples – values of flow and pressure in the compressor outlet for a given compressor operating point)
– depicting of the compressor working regime
Suggested software for surge control systems provides protection against surge together with more efficient compressor operation, especially in process applications that involve variations in the gas mixture and temperature.
CFD ANALYSIS AND OPTIMIZATION OF A COMPENSATED SPOOL VALVE GEOMETRY
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
G. Del Vescovo and A. Lippolis,
2006, August 2006
view abstract
In the past few years the use of computational techniques in the study of the hydraulic valves has become very
widespread. In fact, these techniques allow the study of the spool and sleeve geometry before the building of a
prototype thus allowing a geometrical optimization without expensive experiments. In this paper a detailed analysis of
the different fluid dynamic effects produced by a compensation profile on a hydraulic directional control valve will be
presented. In particular, a procedure based on the successive corrections of two different initial theoretical hypotheses
will be presented. Moreover, the “saturation curves” method will be used to investigate the effects produced in the valve
fluid dynamic behaviour due to different body valve lengths and compensation profile angles. The proposed method can
be considered of general validity and should represent a new powerful tool for valve designers using CFD
(Computational Fluid Dynamics ) techniques.
CFD ANALYSIS OF A FLOW CONTROL VALVE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Domagała,
2008,
pp. 445-450,
Juli 2008
view abstract
The paper presents a CFD analysis of three ways flow control valve, which was aimed at investigation of valve
behaviour during operation. To investigate the flow phenomena during valve operation an FSI simulations was used.
This type of CFD analysis requires preparing model in a specific way with specific boundary conditions, as well as
preparing equation of motion for valve components. During this simulation grid of the model is deforming what allowed
to capture dynamic behaviour of the valve. There was presented in the paper exemplary results for FSI simulations of
the flow control valve. The FSI simulation was carried out in Ansys CFX code.
CFD Analysis of a Novel High Speed Rotary On/Off Valve
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
M. Wang and H. Tu and M. Rannow and P. Y. Li and T. Chase,
2010,
volume 1,
pp. 283-294,
Juni 2010
view abstract
In this paper, the flow inside a novel type of high speed rotary on/off valve is analyzed using CFD
(Computational Fluid Dynamics). The valve fluid domain contains three sections: inlet toroidial pressure
rail with nozzles, center PWM section, and outlet turbine. A CFD model is created for each section, and then
verified. The equations that predict the valve performance has been validated for the inlet rail with nozzles
and the outlet turbine. For the center PWM section, a semi-empirical formula predicting the pressure drop
as a function of spool geometry and flow rate is developed. This is used for optimization of the valve
geometry to minimize overall loss. The CFD tool is also used to minimize the valve compressible volume.
CFD ANALYSIS OF A PNEUMATIC VALVE METERING SECTION
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
G. Del Vescovo and A. Lippolis,
2006,
volume 2,
pp. 557-569,
Juni 2006
view abstract
In this paper, a detailed fluid dynamic analysis of a pneumatic directional control valve metering section will be
presented exploiting the numerical results provided by the commercial CFD (Computational Fluid Dynamics) code
Fluent ™.
In fact it is well known, in the industrial field, the necessity to know with sufficient accuracy, the fluid dynamic
characteristics of the pneumatic valves, and in particular the behaviour in presence of the critical conditions, because
of the very important effects produced on the control systems performance.
In this work the pressure, Mach number and density fields provided by the code at a middle valve opening will be
analyzed when the critical conditions occur.
The analysis will be carried out exploiting the topics of the bidimensional gas-dynamics in order to test the accuracy
and the physical validity of the obtained results.
Moreover the global results regarding the flow rate and the flow force values will be presented, considering cases at
different pressure drop values and different valve openings.
In particular the deep differences between a pneumatic valve and a hydraulic valve, extensively analyzed by the authors
in the past, will be highlighted.
CFD ANALYSIS OF A TORQUE DETECTED TYPE FLOW METER
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
T. Ichiyanagi and T. Nishiumi and T. Kuramoto,
2006, August 2006
view abstract
A unique flow meter has been already proposed by the authors. It utilizes a lateral flow force generated on the
pressure sensing plate, which is placed in the divided rectangular flow channel. In the previous works, the mathematical
model based on the laminar viscous flow analysis was described and the design criterion was established by examining
the fundamental characteristics. This paper addresses the theoretical analysis of the present flow meter using the
computational fluid dynamics (CFD) approach to examine the flow behavior and the pressure distribution inside the
flow meter. CFD analysis is carried out under the various dimensional configurations and boundary conditions. The
flow versus torque characteristics is derived from the obtained pressure distribution results and then compared with the
analytical model that is used for the design evaluation of the flow meter.
CFD Analysis of Flow Forces on Direct Acting Relief Minivalves
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
D. Huguet and E. Codina,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 201-210,
November 2003
view abstract
The change of momentum due to the high flow velocity and change in the jet angle across the valve creates a variation of the flow forces and sometimes the instability of the component. Different jet configurations and flow patterns can appear separated or reattached configuration, different vortical structure, etc. CFD analysis can aid to fluid power researchers to study these flow forces in different geometries to treat all these aspects. In this paper, a Direct Acting Relief Minivalve is analysed by the use of the CFD package Fluent ®. There is a connected phenomenon between the fluid mechanics and the mechanical multi body component behaviour.
CFD Analysis of Flow Forces on Spool Valves
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
G. Del Vescovo and A. Lippolis,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 315-331,
November 2003
view abstract
This study deals with the analysis of the fluid dynamic effects produced by a variable slope
chamfer realized on the spool edges of a traditional directional control valve. The main
purpose is the comparison between the results deriving from a theoretical approach and the
numerical results provided by the commercial CFD code “Fluent”. In particular, the two
possible flow directions have been analyzed in order to simulate the flow conditions of the
two metering sections opened by the axial spool travel. The paper puts in evidence the
difference between the theoretical flow conditions and the actual ones pointing out the
advantageous or disadvantageous effects produced by the chamfer at the different valve
opening values.
CFD ANALYSIS OF PILOT OPERATED RELIEF VALVE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
H. Momeni and E. Lisowski,
2008,
pp. 493-500,
Juli 2008
view abstract
Pilot operated relief valves are very often used in hydraulic drive and control systems. The aim of the valve is to secure
hydraulic system against pressure increase during operation, also in low ambient temperature. One of the most
important features of hydraulic valves is a pressure drop that occurs during fluid flow. Analytical formulas do not allow
estimating pressure drop very precisely due to complex geometry of flow paths. More accurate results might be
obtained by using CFD analysis. Therefore, in the paper was presented application of Ansys CFX code to estimate flow
resistance for pilot operated relief valve. CFD analysis was also used to evaluate an influence of flow path geometry on
value of pressure drop. CFD analysis was also used to investigate flow phenomena during flow of fluid with very high
viscosity.
CFD Analysis of the Intake Manifold of a Hydraulic Circuit
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
R. Paoluzzi and E. Sedoni,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 29-48,
November 2003
view abstract
The paper deals with an application of CFD tools to investigate the overall pressure losses
encountered in the intake manifold of a hydraulic circuit used in an agricultural tractor. The
investigation technique focused on the trial of available tools for actual geometry transfer from
CAD to CFD programs, in order to get an effective design loop for industrial application.
Many features of the procedure will be highlighted, and a full investigation of the internal flow
field presented. The industrial application allowed an improved placement of the pressure
ports with respect to the initial design and a better shaping on internal surfaces according to
expected flow conditions.
CFD Simulation of Compressible Fluid Flows Using Conservation Element Method
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Changzheng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 439-442,
April 2005
view abstract
The space-time conservation element and solution element (CESE) method is applied to solve compressible fluid flow problems. In this method, the flow variables and their first order spatial derivatives, i.e., solution slopes, are treated as independent unknowns. A staggered space-time grid stencil is used to construct explicit and efficient time marching schemes. The flow variables are determined by enforcing the governing conservation laws in a conservation element surrounding a solution node. The solution slopes are evaluated with a procedure of weighted averaging the biased spatial derivatives of flow variables. This procedure usually requires the use of a user-defined weighting parameter. In this paper, we propose a parameter-free approach that combines an aggressive evaluator for the biased derivatives with a slope limiter of the minimal module function. We tested our scheme by solving the Euler equations for a benchmark wind tunnel problem. It is showed that the scheme is able to capture shocks and other discontinuous solutions sharply and accurately.
CFX/Simulink co-simulation of a wave energy converter
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
A. Roberts and M. Schlotter and A. Plummer and D. Tilley,
2010,
pp. 277-291,
September 2010
view abstract
This paper describes a CFX/ Simulink co-simulation strategy for wave energy converters, which comprise of a floating buoy and a hydraulic power take-off (PTO). ANSYS CFX computational fluid dynamics (CFD) code is used for the hydrodynamics model of a free-surface ocean wave, and the Matlab/ Simulink SimHydraulics toolbox is used to simulate the hydraulic PTO system. Two indirectly coupled hydrodynamics-body-hydraulics interaction simulations are performed with this detailed model, and results are compared to an uncoupled simulation with an idealised representation of the PTO system. In the simplified model, the hydraulic system has a damper characteristic, so that the dynamics of the buoy can be treated as a forced mass-damper system with a constant damping coefficient. The forcing term comes from the fluids model, the damper appears in the hydraulics model, and the mass is included in the equation of motion for the system. It is found that this simplification works well for rough initial studies. However, certain PTO control methods are responsible for oscillations in the buoy velocity and hence in the power output of the system. If this effect is to be analysed, full co-simulation must be performed.
Challenges for the International Fluid Power Community
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
R. Burton,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 26-31,
April 2005
view abstract
This discourse is about the international fluid power community and its challenges to remain one in the future.
I will talk a little about the size of our international community, benefits to the fluid power industry from internationalization, and some challenges and solutions thereof.
Changing the Paradigm
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
P. Achten,
2007,
volume 3,
pp. 233-24,
Mai 2007
view abstract
The stronghold of the hydraulic industry is the cylinder. Nothing beats a hydraulic cylinder if it comes to compactness, durability, stiffness, or costs. In the field of
rotational power however, hydrostatic drives have a strong competition from mechanical and electrical transmissions. Whereas hydrostatic transmissions are favoured for their power density and variable transmission ratios, the lower efficiency
(especially at part load and break away conditions), higher noise levels and higher costs offset these strengths. As a result the mobile hydraulic industry is locked in the (albeit
large) market niche of excavators, loaders and other off-road machines where hydraulic cylinders are a must.
The floating cup principle for hydrostatic pumps, motors and transformers can change this situation. Its high efficiency and starting torque, the low pressure and torque variations, the high power density and the low cost design enable the realization of a full hydrostatic drive train with in-wheel hydraulic hub units in all wheels. The floating cup principle also allows the realization of the Innas Hydraulic Transformer. Finally, the combination of in-wheel hydrostatic motors and hydraulic transformers creates the opportunity for making a ‘hydrid’: a hydrostatic hybrid vehicle having all the
advantages of hybrid electric vehicles but without the cost increase of these vehicles.
Characteristics Analysis of Suspending System in Static Balancing Machine for Marine Propeller
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. Wang and E. Yang and J. Zhang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 803-807,
April 2005
view abstract
The paper deals with a fully hydraulic static balance machine for huge marine propeller, which uses large-scale hydraulic spherical bearing to suspend propeller measured. The mathematics model of suspending system in static balance machine is set up, the nonlinear differential equations of the system is derived. Two kinds of situations of the supporting collet are considered for the elasticity deformation and no elasticity deformation. Then, analysis of the dynamic characteristics is done with the changes of the supply pressure, load, structural parameters of spherical hydrostatic bearing and the effective bulk modulus of oil. Finally, some conclusions are drawn, which has an important significance to the design of fully hydraulic static balance machine.
Characteristics of digital hydraulic pressure reducing valve
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
T. Lähteenmäki and M. Ijas and E. Mäkinen,
2010,
pp. 69-82,
September 2010
view abstract
Development in the field of digital hydraulics has been very fast lately. Some of the main focuses of the research have been in developing faster acting valves, more energy efficient systems and developing digital actuators. However the area of pressure control is still relatively uncharted territory.
In this study a digital hydraulic pressure reducing valve system was developed and its characteristics were measured and compared to a high-quality analog pressure reducing valve. The goal was to improve linearity, hysteresis and to reduce dependence of the pressure on the volume flow, which typically are disadvantages of normal analog pressure reducing valves.
The studied digital hydraulic pressure reducing valve system consists of two six-valve DFCUs (Digital Flow Control Units) and a controller with a separate pressure feedback sensor of the control volume. Common, rather slow, on/off -cartridge valves were used with a separate fixed orifice plates to get binary coded nominal flow rates. For controller a basic PID -controller was chosen in order to make it easy to tune and with low demand for computing power. The controller was realized with a dSPACE real-time system. The study introduces a few ways to improve the performance of the digital hydraulic pressure reducing valve system. Delay compensation can be used to reduce pressure peaks in state changing situations, antiwindup -system was adopted to ease problems in flow saturation situations and booster circuits was used for faster valve actuation. Measured results are shown and some still remaining problems and the need for the future research are discussed.
Characteristics of Proportional Control Valve Using Tap Water
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
F. Yoshida and S. Miykawa,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 445-456,
März 2010
view abstract
A water hydraulic proportional control valve using tap water as working fluid is a fluid control device combining high hygiene and environmental friendliness. In this valve, a spool is driven by a proportional solenoid while floating in a sleeve with hydraulic bearings to prevent friction with the sleeve. Previous studies reported the characteristics of the valve at a low supply pressure of 7 MPa. In the fields of semiconductor, molding, medicine, and cosmetics production, driving such valves with higher accuracy in higher pressure ranges will be required for improved hygiene, safety, and environmental friendliness. This paper describes the pressure and flow characteristics of this valve at a high supply pressure of 14 MPa and clarifies how various parameters related to the hydraulic bearings and the clearance between the spool and the sleeve affect the characteristics of the valve.
Characteristics of Teleoperated Skid Steered Mobile Machine
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
J. Vilenius and A. Raneda and K. Huhtala,
2004,
pp. 587-597,
Juni 2004
view abstract
This paper deals with the development work of the skid steered mobile machine. The goal of this paper is to describe the teleoperation control of a small hydraulic mobile machine and compare its properties to a manually controlled small hydraulic mobile machine.
The teleoperation changes the construction of the mobile machine and gives some technical demands for example some safety issues. The differences and similarities of the teleoperated and manually controlled mobile machine are investigated.
The first prototype of the teleoperated mobile machine is introduced. The teleoperation system developed is devided in three major areas: local control of the mobile machine, the design of the user interface in the remote control station and the wireless transmission of data.
The advantages of the computer control such as the concept of virtual gears are introduced to manage the hydraulic power. The future visions of the next prototype of the teleoperated mobile machine are also introduced.
Characterization and Attenuation of Sandwiched Deadband Problem Using Describing Function Analysis and Application to Electrohydraulic Systems Controlled by Closed-Center Valves
Song Liu and Bin Yao,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
Mai 2009
view abstract
Unlike input deadband, the sandwiched deadband between actuator and plant dynamics is very difficult to be explicitly compensated for due to the proceeding actuator dynamics whose effect may not be negligible. The paper presents a practical way to overcome the design conservativeness of existing methods in dealing with sandwiched deadband. Specifically, a describing function based nonlinear analysis method is proposed to characterize the effect of the sandwiched deadband on the stability and performance of the overall closed-loop system. The analysis results can be used to determine the highest closed-loop bandwidth that can be achieved without inducing residual limit cycles and instability. Optimal controller parameters can then be found to maximize the achievable closed-loop control performance. The technique is applied to an electrohydraulic system controlled by closed-center valves and a nonlinear feedback controller. Simulation results showed severe oscillations as the feedback control gains are increased to the predicted threshold values. Comparative experimental results also showed the effectiveness of the proposed method in reducing the conservativeness of traditional design and the improved closed-loop control performance in implementation.
Combined Controller for Test System of High Capacity Hydraulic Pump
Wenjun Meng and Jeffrey C. Suhling,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
September 2010
view abstract
A combined controller (CT-PBC) by contact task control (CTC) with passivity based controller (PBC) is introduced to control test system of high capacity hydraulic pump (HCHP) to measure its properties. It is compared with a vector controller; a torque feedback based combined controller, and two neural network controllers. The results gained from comparing and analyzing these controllers show that under different outlet pressures of HCHP, CT-PBC has good stability and robustness, which meet the requirements to test HCHP. CT-PBC is also simpler and better than other controllers in general.
Combined Heat and Air Generation – A Technical Study
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
P. Eret and C. Harris and C. Meskell and G. O'Donnell,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 235-245,
März 2010
view abstract
Compressed air generation represents one of the most significant hidden costs in manufacturing plants. While it has been shown that centralized compressed air generation may not be the most cost effective or energy efficient configuration, centralized air generation is most common in large scale facilities. Thus, from a total cost viewpoint, generating compressed air in a single or at most in a small number, of installations within a factory is accepted as the standard, if not the best, practice. This concentrating of plant offers the possibility of generating compressed air by directly coupling the compressor shaft to a heat engine, in an approach similar to combined heat and power. Currently the compressor is typically driven by an electric motor, which is typically supplied by a grid connection to a thermal generating plant; thus in this combined heat and air (CHA) scenario, the electricity generation and transmission stage is removed. This is not a new proposal. This approach of generating compressed air is commonly used in small scale applications where the point of use is far removed from an electricity supply (e.g. in the agricultural sector, or in civil engineering construction) and increasingly even in manufacturing environments. It is shown here that using a gas turbine, with regeneration, will yield a 43% improvement in operating efficiency. This does not require a balanced heat load demand, as the waste heat is reused in the generation of shaft power, although in principle, the total energy efficiency could be improved further by utilization of the low grade heat, in space heating, for example. It is concluded that a Combined Heat and Air (CHA) approach deserves further study.
Combining Leakage and Orifice Flows in a Hydraulic Servovalve Model
Bora Eryilmaz and Bruce H. Wilson,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 576-579,
September 2000
view abstract
Experiments indicate that at small servovalve spool displacements, leakage flow between the valve spool and body dominates the orifice flow through the valve. In precision positioning applications, where the servovalve operates within the null region, this flow, if ignored, may severely degrade the performance of a conventional servohydraulic design. We have developed an improved servovalve model that combines both leakage and orifice flow. The model was developed by reviewing experimental leakage flow data and identifying a simple mathematical form that (1) made physical sense and (2) replicated experimental data. When combined with orifice relations, the model extends the accuracy and region of applicability of existing servovalve models. Furthermore, the combined model is easily parameterized using available manufacturer data.
COMPARASION OF PISTON AND BLADDER HYDRO-PNEUMATIC ACCUMULATORS PROPERTIES
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
P. Kucybala and J. Pobedza,
2006,
volume 2,
pp. 623-630,
Juni 2006
view abstract
This paper presents results of stand tests, performed to determine phenomena occurring during charging and
discharging of hydro-pneumatic accumulator. Two types of similar size (about 5 litres) accumulators were tested:
piston one and bladder one. Investigations have determined the influence of such parameters as: pre-charge pressure,
pressure ratio, lay time, and thermal conditions on accumulator efficiency. Also these analyze allowed to compare
energy storage and recuperation properties for two tested types of hydro-pneumatic accumulators.
COMPARATIVE TESTS OF MICROPROCESSOR CONTROLLED LOW SPEED HYDRAULIC MOTORS IN THE RANGE OF LOW ROTATION SPEEDS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
A. Skrocki and J. Szlagowski,
2008,
pp. 124-134,
Juli 2008
view abstract
This study is devoted to modelling and comparative test of hydraulic motors: radial piston motor type MR160 and
orbital motor type GMSW320 in the range of low rotation speeds. Catalogue technical specification of examined low
speed rotation motors: radial piston and orbital type, gives corresponding values of 1 rpm and 10 rpm, but the
requirements of a manipulator are higher and amount to approx. 0,02 – 0,03 rpm, at required rotation speed span of
approx. 1500. In order to fulfil functional requirements for modern rotation gear, microprocessor control has been
applied in above motors operating regulation system. Applied method allowed for significant reduction of stable
rotation speed of examined motors, at the same time extending application range of the motors.
Comparative Tribological Investigations of Continuous Control Valves for Water Hydraulics
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
F. Majdic and J. Pezdirnik and M. Kalin,
2007,
volume 3,
pp. 419-430,
Mai 2007
view abstract
Reduction of oil usage and its almost daily increasing price is directing world development in the field of hydraulic fluids towards alternative sources. One possible alternative source is water, which is environmentally blameless, low-cost and
nonflammable.
Taking into consideration the body accessible information about water power-control hydraulics (PCH), we constructed a simple hydraulic test rig to investigate the basic tribological and hydraulic behaviour of such systems under pressures up to 150 bar and flows up to 30 L/min. With that aim we designed and constructed a proportional 4/3 directional continuous acting spool type sliding valve, a simplified model but still with
the shape and working parameters resembling real valves. Tribological properties and static as well as dynamic behaviour can be investigated on this model by employing
components of different materials. All other applied components of this test rig were taken from normal serial production, meaning that these components are available on the market. In this work, a design of the test rig and testing schemes are presented, while the real-scale preparation and testing procedures are on-going.
However, in order to ensure a satisfactory useful life time of the proportional 4/3 directional control valve, an optimal tribological pair is required in the valve. With this
aim in mind, we carried out preliminary tribological tests of different material-pairs lubricated with additive-free distilled water. The tested materials were stainless steel,
PI, PEEK and Al2O3. The results of the preliminary tribological tests of different material pairs are described in this paper. The best material pair considering low wear and a low coefficient of friction was obtained with graphite-modified PEEK composite against Al2O3.
Comparing Control Methods of Feed Force
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Virvalo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 134-138,
April 2005
view abstract
Hydraulic cylinders are typical actuators in feed force control for instance in rock drilling and wood sawing applications. Quite fast responses in both directions (increasing and decreasing force) are required in both drilling and sawing applications. The penetration speed, quality of drilled hole and cut wood surface, efficiency, and jamming depend strongly on the feed force control. Different method to realize feed force control in order to maximize penetration rate and avoiding jamming are discussed. Constant torque control proves to be a good method. Results of simulation with well verified models are shown and discussed.
Comparing Hybrid Power Transmission Systems of Work Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
H. Hänninen and J. Juhala and A. Sinkkonen and A. Hentunen and M. Pietola,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 189-200,
März 2010
view abstract
Work machines perform a variety of work cycles of which many are theoretically zero energy processes (lifting/lowering, acceleration/deceleration). This feature offers a possibility to recover at least some of the released potential/kinetic energy during the lowering/deceleration phase and reuse it in order to reduce the need for external energy. The recovered energy can be stored in several ways, in mechanical components (e.g. flywheel), in hydraulic components (hydraulic accumulator) or in electric components (e.g. battery) which all have their advantages and disadvantages. When comparing the characteristics of these components one must also keep in mind that every energy conversion induces losses and therefore the number of conversions should be minimized. This paper presents four different energy setups for a hypothetical hydraulically operated truck and compares them by means of simulations. The reductions in energy consumption with regenerative systems compared to the original system were found to be from 10 to 30 percent, depending on system configuration.
Comparison of Cavitation Erosion Test Results Between Vibratory and Cavitating Jet Methods
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
A. Yamaguchi and K. Inoue and T. Kazama and J. Onoue,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 125-130,
November 1997
view abstract
The relationship of the test results between the vibratory and cavitating jet methods was clarified experimentally. Six types of metallic specimens which were made of aluminum alloy, superduralumin, high-strength brass, stainless steel, carbon steel and chrome-molybdenum steel were tested. The ratio of eroded volume by the vibratory to cavitating jet methods became constant as the time proceeded. The eroded volume of aluminum alloy was the largest, and that of superduralumin, that of high-strength brass, that of steel, in order. The order agreed well with both test methods. Striation, plastic deformation and fatigue fracture were observed.
COMPARISON OF CAVITATION EROSION TEST RESULTS BETWEEN VIBRATORY AND CAVITATING JET METHODS
A. Yamaguchi and T. Kazama and K. Inoue and J. Onoue,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 25-30,
März 2001
view abstract
The relationship between the vibratory and cavitating jet test methods was determined experimentally. Six metallic
specimens were made of aluminum alloy, superduralumin, high-strength brass, stainless steel, carbon steel and chromium-molybdenum steel. The specimen surface was eroded as fine and uniform pattern with the vibratory method, but
was rough and ring-shaped with the jet method. Striation and plastic deformation were clearly observed in the specimens
eroded by jet cavitation. The volume loss was the largest for aluminum alloy, followed by superduralumin, highstrength
brass and steel. Both test methods yielded the same descending order for the volume loss. The ratio of volume
loss by the vibratory method compared to the cavitating jet method became constant as the time proceeded.
Comparison of Digital Hydraulic and Traditional Servo System in Demanding Water Hydraulic Tracking Control
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
M. Linjama and J. Seppälä and J. Mattila and M. Vilenius,
2008,
pp. 393-403,
September 2008
view abstract
The remote maintenance of the ITER fusion reactor will be based on pure water hydraulics. Reliability and accuracy requirements are high because of narrow space, high radiation and extreme costs. Digital hydraulics is a potential solution because it uses robust on/off valves and is fault tolerant. In this paper, the performance of the traditional and digital hydraulic servo system is compared in a 1-DOF mockup. The traditional servo system consists of a servo valve and state feedback controller. The digital hydraulic servo system has 4x5 on/off valves and model based feedforward controller together with P-controller. Experimental results show similar tracking performance in both systems.
Comparison of EMA and HA performance for dynamic load simulators
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
W. Karam and J.-C. Mare,
2006,
pp. 211-224,
September 2006
view abstract
The performance of electro-mechanical actuators is evaluated in comparison with hydraulic actuators for dynamic loading applications. The first part is dedicated to the analysis of mechanical architectures with respect to integration and mechanical reduction. In the second part, a design methodology is proposed to optimise the selection of the motor-screw combination. The third part concerns the modelling of the actuator with special consideration to the nut-screw transmission. In the last part, the natural open loop dynamics of both kinds of actuators are compared to identify key design criteria.
Comparison of Linear, Nonlinear, Hysteretic, and Probabilistic Models for Magnetorheological Fluid Dampers
Corina Sandu and Steve Southward and Russell Richards,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
November 2010
view abstract
Magnetorheological (MR) fluid dampers have a semicontrollable damping force output that is dependent on the current input to the damper, as well as the relative velocity. The mechanical construction, fluid properties, and embedded electromagnet result in a dynamic damper response. This study evaluates four modeling approaches with respect to predicting the multi-input single-output behavior of an experimental MR damper when the inputs are band-limited random signals typically encountered in primary suspension applications. The first two models in this study are static in the sense that there is a unique output for any given set of inputs and no dynamics is present in either model. The third model incorporates a dynamic filter with the nonlinear model to exhibit hysteretic effects, which are known to exist in actual MR dampers. The fourth model is probabilistic and illustrates the dynamic nature of an actual MR damper. The results of this study clearly show the importance of nonlinear and dynamic effects in magnetorheological damper response. This study also highlights the importance of characterizing magnetorheological dampers using excitation signals that are representative of an actual implementation.
Comparison of Present Methods of Hydraulic Oils Filtration Technology (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
B. Pavlok,
2006,
pp. 83-88,
Mai 2006
view abstract
Comparison of Present Methods of Hydraulic Oils Filtration Technology.
In this paper the comparison of the most widely used methods of the oil filtration, i.e.
mechanical filtration and electrostatic cleaning of oil are presented. The confrontation is
made not only from the aspect of quality of filtration technology, but also from the economical
aspect especially the aspect of operating costs.
The operating costs include especially: costs of filter elements exchange, costs of oil
exchange, costs of leasing facility for electrostatic liquid cleaning (further only ELC), power
consumption costs (up to running of ELC or negotiation of pressure losses on filter), idle time
and the connected costs including, fall-out loss (of production), diagnostics of machine
failure, reparation or exchange of damaged hydraulic component.
The comparison of operating costs connected with the classical mechanical filtration and the
use of ELC was done within the Bachelor thesis at the Department of Hydromechanics and
Hydraulic Equipment. The bachelor focused his work on the determination of the optimal
working time and the working intervals of the ELC application.
It was the hydraulic system of machine with the proportional control and the oil filling of
1500 dm3. This hydraulic system works in a very dusty environment.
In 2001 the periodical monitoring of the hydraulic oil contamination was started and the
application of ELC was set to 5 times, always after a breakdown (see Fig. 1). The trend was
evaluated after one year and time of ELC application was extended – see Fig. 2. As the trend
was still increasing, time of ELC application was extended again. In 2003 the trend turned
down (Fig. 3) and no perturbation breakdown occurred.
From the described results it can be concluded that the optimal intervals and application time
of ELC can set properly only in operating conditions by periodical long-time monitoring of
contamination trend and adaptation of intervals and application time of ELC.
Comparison of Slipper Structures in Water Hydraulic Axial Piston Pump
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
M. Rokala and K. T. Koskinen,
2010,
volume 2,
pp. 827-836,
Juni 2010
view abstract
Hydrostatic slipper bearing is an effective way to maintain bearing between slipper and swashplate in water hydraulic
axial piston pumps. The objectives in this paper are to compare the deformations, properties and load carrying
capacities of five different slipper structures without hydrodynamic effect. In this paper two of the slippers are made from PEEK, one is made from stainless steel and other two of the slippers are machined from combination of PEEK
and stainless steel. The deformations of each slipper structures are calculated with the finite element method (FEM). The experimental results of the deformation and friction values of two of the slippers are compared. Because at the moment the pressure level in axial piston units in water hydraulics is rather low, calculations are made covering a wide pressure range to get information for possible future adaption for higher pressures. Based on the calculations, measurements and water properties guidelines of the slipper design are presented and constraints of different structures are shown.
Comparison of software for simulation of fluid power systems
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
H. Mann and S. Willing and M. Holfeld,
2006,
pp. 265-275,
Mai 2006
view abstract
In the past, the efficiency of simulation software used to be evaluated mainly
according to the computer time required for executing it. As the cost of computer time
dropped down dramatically since then, the cost of computing is dominated by the human
factor nowadays. In other words, any evaluation of software efficiency should take into
account the time and qualification required from its users. Therefore, efficient software
should be as much as possible user friendly and computationally robust. There is nothing like
the best software, however. We must always ask “Best for what?”
This paper gives a survey of different approaches to modeling and simulation of fluid power
systems and assesses their suitability to the conceptual, functional and physical phases of the
design and diagnostics of these systems. Model descriptions in the form of equations, block
diagrams, bond graphs and multipole diagrams are considered. Also examples of software
packages exploiting these approaches are given. Among these are AutomationStudio,
AmeSim, Dymola, Dynast, FluidSim, SimulationX, Simulink/Matlab and 20-Sim. Besides this,
computational robustness of the algorithms used in some of these packages is considered in
the paper. Unfortunately, a robustness comparison of the packages using benchmark
examples was not possible without buying a full version of the packages. A demo version is
available for only few of the packages, and if it exists it allows usually submitting very trivial
problems only.
The user-friendliness of some of the packages is degraded by a complicated input language,
and by the necessity to compile the input data after their each minor modification. The
component models are usually closed so that the users cannot modify or even see them. Also
the output data are often accessible in plotted, but not in the numerical form, which makes
troubleshooting of computational problems difficult, or even impossible. The number of
demonstration examples is usually very limited.
In contrast to most of the existing simulation packages, the Dynast software system, which is
briefly presented in the paper, is very user friendly and robust, yet it is freely accessible
across the Internet at http://virtual.cvut.cz/dynast/. Its usage is very easy and intuitive as it is
supported by graphical dialogs and there is no need to learn its input language. Algebrodifferential
equations can be submitted in a natural textual form. For physical-level models in
the graphical form representing the real system configuration, these equations are formed
automatically. The submitted data is continuously checked for eventual errors the occurrence
of which is indicated and their reason explained. The Dynast libraries, that contain a large
number of component submodels from various engineering disciplines, are fully open. Thus
the users can easily add their own submodels. Publishing of simulated problems and new
models is supported by automated documentation systems. If used in or outside a class-room,
students’ activities can be monitored and corrected by their tutor across the Internet. Also
across the Internet, Dynast can ‘power’ virtual experiments, or to communicate with the
Matlab toolboxes when used for control design.
comparing the simulation packages both from the point of view of their user friendliness and
robustness. A seed of such a collection of benchmark examples is already available at
http://virtual.cvut.cz/dyn/examples/toc-examples-fluid-power.html. The examples can be
modified and re-solved interactively across the Internet by Dynast installed on the server of
the Czech Technical University. Members of the fluid-power community are encouraged to
contribute to the collection the problems they found difficult to solve.
Comparison of Three Different Concepts for a Variable Valvetrain for Huge Combustion Engines
Proceedings of the 3rd FPNI-PhD Symposium on Fluid Power, Terrassa, Spain
A. Plöckinger,
2004,
pp. 453-462,
Juli 2004
view abstract
Emissions reduction and performance improvements of combustion engines is a permanent topic in R&D not only for engines of passenger cars but also for huge engines for trucks, locomotives, or for power generation. One decisive step forward in this respect is the realization of variable valvetrains for engine valves. Such systems offer much higher flexibility to adopt the inflow of air and the outflow of the exhaust gases in order to reduce throttling losses, improve the mixing of air with the fuel, or to handle specific modes of operation, like the Miller Cycle. Thus, a high potential exists to increase power density and the combustion cycle efficiency. We will compare several electrohydraulic systems with respect to power consumption, flexibility, and reliability for valvetrain systems found in patent or other literature and a system developed by the authors. The latter is a novel energy saving system exploiting a hydraulic spring concept. Detailed experimental results obtained from a functioning test rig of the authors' system allow to tune the simulation models and yielded a good insight in the main technical difficulties with electrohydraulic variable valvetrains.
Comparison of Three Different Concepts for a Variable Valvetrain for Huge Combustion Engines
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Plöckinger,
2004,
pp. 453-462,
Juni 2004
view abstract
Emissions reduction and performance improvements of combustion engines is a permanent topic in R&D
not only for engines of passenger cars but also for huge engines for trucks, locomotives, or for power
generation. One decisive step forward in this respect is the realization of variable valvetrains for engine
valves. Such systems offer much higher flexibility to adopt the inflow of air and the outflow of the
exhaust gases in order to reduce throttling losses, improve the mixing of air with the fuel, or to handle
specific modes of operation, like the Miller Cycle. Thus, a high potential exists to increase power density
and the combustion cycle efficiency.
We will compare several electrohydraulic systems with respect to power consumption, flexibility, and
reliability for valvetrain systems found in patent or other literature and a system developed by the authors.
The latter is a novel energy saving system exploiting a hydraulic spring concept. Detailed experimental
results obtained from a functioning test rig of the authors' system allow to tune the simulation models and
yielded a good insight in the main technical difficulties with electrohydraulic variable valvetrains
COMPARISON OF VARIOUS DESIGNS OF SOLID BODY COMPENSATORS FOR THE FILTERING OF FLUID FLOW PULSATIONS IN HYDRAULIC SYSTEMS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
J. Mikota,
2000,
pp. 291-301,
September 2000
view abstract
Numerous hydraulic sources create significant flow- and pressure pulsations. Common measures to reduce these
unpleasant effects include accumulators, in particular featuring a 'Pulse-Tone' design, shock absorbers in various
arrangements and novel multiple-volume resonators. In this paper I will compare conventional devices to 3
novel concepts of solid-body compensators, i.e. compensators based on a multi-degree of freedom mass-spring
system, compact l/4 side branch resonators and compensators based on various arrangements of plate/shell
elements. For this comparison, I will use criteria, such as the adjustment of the resonance frequency, mechanical
stresses in the resonator, the ability to compensate frequencies which are integer multiples of a base frequency
as well as compact and cheap design.
Comparison of Various Forms of Oscillators for the Compensation of Fluid Flow Pulsations in Hydraulic Systems
Proceedings of XXVIII Summer School: Advanced Problems in Mechanics 2000, St. Petersburg, Russia
J. Mikota and R. Scheidl,
2001, Juni 2001
view abstract
Numerous hydraulic sources create significant flow- and pressure pulsations. Common measures to reduce these unpleasant effects include accumulators, in particular featuring a 'Pulse-Tone' design, shock absorbers in various arrangements and novel multiple-volume resonators. In this paper we will compare conventional devices to 3 novel concepts of solid-body compensators, i.e. compensators based on a multi-degree of freedom mass-spring system, compact lambda/4 side branch resonators and compensators based on various arrangements of plate/shell elements. For this comparison, we will use criteria, such as the adjustment of the resonance frequency, mechanical stresses in the resonator, the ability to compensate frequencies which are integer multiples of a base frequency as well as compact and cheap design.
Compensation of Variable System Dynamics to Enhance Condition Monitoring for Hydraulic Pumps
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
C. Stammen,
2007,
volume 2,
pp. 433-443,
Mai 2007
view abstract
The paper presents the influences of different hydraulic systems on dynamic pressure signals on an axial piston pump. Due to these influences, pump condition monitoring for a certain application by means of pressure pulsation measurement is not easily applicable to other cases. Focus of the work is the development of a compensation method for variable system dynamics to ease the application of condition monitoring for pumps. The experimental verification was taken out for a variety of operating points. As an outlook, the application of the method on mechanical vibration signal is proposed.
Compositional modelling of fluid power systems using predictive tradeoff models
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
R. Malak and L. Tucker and C. Paredis,
2008,
pp. 423-436,
September 2008
view abstract
System-level decisions can have a large impact on the success of any design project, including those in the fluid power domain. Regardless of efforts by designers to optimize individual fluid power components, poor decisions at the systems level can lead to poor system performance and unsatisfied design requirements. In this paper, we apply the principles of system-level decision making to the design of fluid power systems. We describe a methodology for modeling fluid power component technology using predictive modeling and data mining techniques in a way that facilitates system-level modeling and decision making. We demonstrate the approach on the design of a hydraulic log splitter.
Comprehensive Compensation for the Disturbance Torque of Electro-hydraulic Load Simulator
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
S. Donghai and L. Qinghe and W. Shenglin,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 107-111,
November 1998
view abstract
Electro-hydraulic load simulator is testing equipment used to simulate the actual torque exerted by air on the steering axle of flying object flying over through air. It belongs to the typical passive loading system, in which, in dynamic loading process, the disturbance torque generated by the rotation of steering axle will decrease loading accuracy and influence control performances of loading system. Because the highest rotation frequency of the steering axle may
reach 20Hz, the loading system can not work normally with simple compensation. According to the characteristics of electro-hydraulic simulator, this paper presents a comprehensive compensation method to eliminate the disturbance torque and improve the control performances.
Based on the synchro-compensation, this comprehensive compensation feeds the velocity difference between loading motor and synchronous motor forwards to realize the second
discharge of disturbance torque coupling to the loading system. After founding mathematics model, the performances of the compensated system is analyzed through computer simulation.
The correctness and effectiveness of the comprehensive compensation for eliminating disturbance torque are proved by experimental results.
Compressibility Measurements of Hydraulic Fluids in the Low Pressure Range
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
R. Haas and B. Manhartsgruber,
2010,
volume 2,
pp. 681-690,
Juni 2010
view abstract
This paper presents a test rig for compressibility measurements of hydraulic fluids. Today a lot of effort is put on
simulation of low pressure lines in hydraulic systems. These simulations are important for increasing efficiency of fast
switching applications like hydraulic buck converters or for the reduction of pressure pulsations in suction pipes of
pumps.
Simulation of high pressure systems is quite straight forward. The fluid parameters like density and bulk modulus can
be assumed to be constant and as a result of this the flow equations are very simple e.g. the wave speed in a pipe is
constant. For low pressure simulations these assumptions are not true any more. For example, air release in low
pressure regions generates small air bubbles which cause dramatic changes in the fluid parameters like density and
compressibility. As a result, simulations are only accurate for a special operating point with small variations. In the
more general case of large pressure variations around a low pressure operating point, wave speed and the shape of the
pressure pulses change as the previously discussed parameters do.
The aim of this paper is to present a test rig and first measurements for compressibility identification of hydraulic oil in
the low pressure range. Because of the importance of the initial oil-air ratio, the test rig has the capability to evacuate
the fluid chamber and a device to incorporate an exactly defined volume of air. As a result pressure dependent
compressibility graphs, for a defined value of incorporated air, can be recorded. Finally all problems and results are
discussed; applications for simulations and further measurements will be stated.
Compressible bench flow adaptations to the experimental characterization of pneumatic components. Application to the determination of flow-rate characteristics of a MPYE- 5-3/8-010-B proportional valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Fernández Jiménez and J. Pérez García,
2004,
pp. 193-148,
Juni 2004
view abstract
This paper describes the operating and basic characteristics of a general purpose compressible flow bench
facility developed to accomplish experimental test in fluid dynamics, as well as the required adaptations
according to ISO 6358 for pneumatic fluid power components characterization such as, valves,
regulators, filters, filter-regulators, cylinders,…etc, are described. The experimental characterization of
pneumatic fluid power components, especially proportional valves and servo-valves are required
when their performance must be modelled. The technical characteristics from suppliers are, in
general, insufficient. The sonic conductance, critical pressure ratio, coefficient of compressibility
effect, and effective area, must be specified according to ISO 6358. In addition, the corrected mass
flow rate as function of the absolute inlet pressure and pressure ratio must be calculated.
In this work, the experimental flow-rate characteristics of a Festo MPYE-5-3/8-010-B pneumatic
fluid power proportional valve operating in open-loop circuit control, is obtained. The actual and
corrected mass flow rates, sonic conductance and effective area at different absolute inlet pressures
versus excitation voltage are shown. The corrected mass flow rate has been obtained, departing from
raw data of coriolis effect mass flow meter, in both, with upstream and downstream measuring tubes,
and exhausting directly to atmosphere for different spool positions. This allows to obtain a very
useful experimental correlation between effective area and excitation voltage. Also the hysteresis
effects have been studied. In conclusion, a closed loop circuit control operating is recommended,
since for high excitation voltage these effects are significant.
Computational Fluid Dynamics Analysis of Rotary Blood Pump with Hydrodynamic Bearings
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Q. Han and J. Zou and X. Ruan and H.-Y. Yang,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 373-381,
März 2010
view abstract
A blood pump with hydrodynamic bearings is designed, which can provide a flow of 2-7 L/min against a head pressure of 80-120 mmHg. The impeller is completely levitated by hydrodynamic bearings and driven by a brushless DC motor. In this study, computational fluid dynamics (CFD) analysis is performed to predict flow patterns of hydrodynamic bearings. The effects of bearing clearances on shear stress distribution, as well as the axial and radial force of the bearings, are analyzed in detail.
Computationally Efficient Time Domain Modelling of Fluid Transmission Lines
Proceedings of the ASME Design Engineering Technical Conferences, September 9-12, 2001, Pittsburgh, PA
B. Manhartsgruber,
2001, September 2001
COMPUTATIONAL MODELS FOR EFFECTIVE BULK MODULUS OF HYDRAULIC FLUID
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
J. Kajaste and H. Kauranne and A. Ellman and M. Pietola,
2006, August 2006
view abstract
This paper presents a study of experimental validation of two models for effective bulk modulus of hydraulic fluid. These models include the effect of the compressibility of free air on the gross bulk modulus of the fluid. The model by Nykänen et al. is studied along with the model by the authors. The experimental test system consists of a heavy-duty hydraulic cylinder in which the piston rod is used to introduce fluid volume changes and pressurize the fluid. The measured volume changes are compared with those predicted by the models. The results indicate that both of the mod-els can represent the basic free gas related phenomena with accuracy that is feasible for normal engineering practices. The model by the authors gives the best fit but it has an additional parameter compared with the Nykänen-model. With large volumes of free air in the fluid the pressure histories during compression and expansion phases differ from each other to some extent. At very low pressures the ability of the presented models to predict the measured phenomena is also found insufficient. However the use of the presented models compared with the constant bulk modulus assumption improves the accuracy of the simulation considerably especially in cases where the amount of free air is significant.
Computational Study of the Influence of Roughness on the Friction Behaviour of Step Seals
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
A. Wohlers and O. Heipl and H. Murrenhoff,
2010,
volume 1,
pp. 363-372,
Juni 2010
view abstract
Seals are important machine elements used to ensure the functionality of hydrostatic devices like cylinder applications.
The failure of seals usually results in expensive and time-consuming replacement procedures. At present there is no
established calculation method to predict the dynamic seal process. In Wohlers (2009) a physically based simulation
approach was introduced. Using a steady-state structural mechanics Finite Element Analysis (FEA) the contact
pressure between the seal and the rod is calculated. The contact pressure profile is applied as a starting condition for the subsequent dynamic simulation, which is based on a Fluid-Structure Interaction (FSI). Hydrodynamic pressures
and dynamic contact pressures are considered as well as the seal deformation. In Wohlers (2009) a validation has been
done using dynamic o-ring seals. In Heipl (2010) the simulation model has been extended to step seals. Using the
extended simulation model this paper shows a computational study of the effect of surface roughness on the friction
behaviour of step seals. The simulations are carried out for a non pressurised sealing system.
Computation of Hydrostatic Guideway of Vertical Lathe Ram and Test Equipment Design (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
J. Nevrlý,
2006,
pp. 165-174,
Mai 2006
view abstract
This article will focus on a computation of a hydrostatic guideway of a vertical lathe ram.
Basic data of the solved problem are introduced as well as basic considerations concerning
governing equations describing mutual relations between hydraulic and mechanic quantities.
The equations of Reynolds, Laplace and Hagen-Poiseuille are mentioned. Computations
carried out by means of Excel and Maple are discussed and some schemas and computation
results are shown.
The main goal of the computation and the design of the hydrostatic guideway of an vertical
lathe ram was to prepare the basic documentation of a prototype for the ram maximum load
of Fz=50 000 N, Fx=Fy=22 500 N whereas the maximum ram shift is 550 mm. The course of
the ram load can be seen in Figure 1.
The results of the computation of the hydrostatic guideway of the vertical lathe ram are
introduced and the design of the hydraulic circuit is shown.
Computer Aided Conceptual Design, a Concept Study of Fast Hydraulic 2/2-Way Seat Valves
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
B. Steiner and R. Scheidl,
2006,
volume 2,
pp. 409-420,
Juni 2006
view abstract
In this paper a concept study of 2/2-way seat valves is presented, using a new developed software tool for conceptual design and some computer based methods for assessing model consistency, computational allowability, and model complexity. The conceptual design software helps the designer to declare his/her physical understanding and generates automatically a mathematical description of the model. It links together the graphical domain of sketches/drawings with the symbol domain for reflecting the physical effects and the domain of basic mathematical models for their quantification. It also calculates the constraint matrix from the mathematical model, which maps the functional requirements (FR) from the functional domain to the design parameter (DP) from the physical domain. According to Nam, P. Suh (1990), certain features of this map gives valuable information on the complexity of a design. The constraint matrix can be transformed into a bipartite graph. A bipartite graph is the companion to the constraint matrix and shows exactly the same information. Theses two models are basic principles of constraint theory, which is a powerful tool for evaluating mathematical model consistency and computational allowability. If a mathematical model is consistent and the computation is allowable, the model will be well-posed. Finding the best solution for a technical product is rather difficult. Model complexity gives the designer a tool for evaluating different well-posed mathematical models. To demonstrate this approach a comparative evaluation of three different principles of a 2/2-way seat valve is discussed. These principles are a 2/2-way cartridge valve, a 2/2-way check valve, which are state of the art and a new leakage free2/2-way ball valve with an integrated deformable disk.
Computer Aided Design and Optimization of a Test Rig for Magneto-Rheological Fluid Behaviour
Proceedings of the 1st International Conference on Computational Methods in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
B. Manhartsgruber and A. Kainz and R. Scheidl,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 401-412,
November 2003
view abstract
Magneto-rheological (MR) fluids are liquids whose rheological properties can be controlled by the application of an external magnetic field. Commercial applications of MR fluids can be found in vibration dampers and brakes. The MR fluid offers three modes of operation. Only two of them are frequently used in applications: Either the direct shear mode, where the relative motion of two magnetic poles separated by the fluid generates shear forces, or the valve mode, where the magnetorheologial effect is used to restrict the flow through passages and the resulting pressure difference is used for hydrostatic force generation. Because of its non-linear behaviour, the third mode of operation, the so called squeeze mode is up to now used for small amplitude vibration damping only. A better insight into the behaviour of MR fluids in the squeeze mode is expected to give rise to new applications. The present paper describes the design of a test rig for the exploration of the fluid behaviour in the squeeze mode. While the basic task of squeezing the MR fluid out of a narrowing gap can easily be accomplished, the measurement of hydrostatic pressure and shear stress at the boundary of the MR fluid film is very demanding. Finite element analysis is used for the design and optimization of both the mechanical and electromagnetical properties of the shear stress sensor.
Computer Aided Development of a New Bernoulli Gripper
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
W. Gauchel and M. Zindl and E. Bürk,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 279-290,
März 2010
view abstract
The paper describes the development of a low-contact gripper which utilizes the Bernoulli Effect to produce its gripping force. After explaining the principle function of the gripper, the article presents results obtained from CFD simulation to demonstrate flow conditions inside the gripper as well as the layout of the main elements. The paper goes on to describe the test bench used to test the Bernoulli gripper and explains the information gained. It concludes by comparing practical test results with simulation results.
COMPUTER AIDED OPTIMIZATION OF BEARING AND SEALING GAPS IN HYDROSTATIC MACHINES - THE SIMULATION TOOL CASPAR
U. Wieczorek and M. Ivantysynova,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 7-20,
April 2002
view abstract
The simulation tool CASPAR (Calculation of swash plate type axial piston pump and motor) is presented in this pa-per. Based on the simulation of the flow through the lubricating gaps in swash plate type axial piston machines the pres-sure, velocity and temperature fields in the considered gaps can be determined. This allows the calculation of the main losses generated in the machine due to viscous friction and gap flow. The individual gaps are connected in a complex way to each other. The calculation of the gap flow requires the determination of the instantaneous gap heights for all considered gaps. This is realized by solving the motion equation for all moveable parts of the rotating group. For deter-mination of pressure dependent external forces the instantaneous pressure in the displacement chamber is calculated simultaneously. The program further calculates the instantaneous inlet and outlet flow of the swash plate machine for pumping and motoring mode as well as internal volumetric losses.
COMPUTERIZED GENERATION OF NOVEL GEARINGS FOR INTERNAL COMBUSTION ENGINES LUBRICATING PUMPS
G. Mancò and S. Mancò and M. Rundo and N. Nervegna,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 49-58,
März 2000
view abstract
The paper presents a general procedure for the computerized design of gerotor lubricating pumps for internal combustion
engines. The approach is applied to gerotor gearings with circular arc profiles, nowadays the most used, but also
to pumps featuring novel parabola arc profiles. Obtained results allow, on one hand, to guide the designer in selecting
gerotor (circular arc) prototypes best suited for a given application and, on the other hand, to scrutinize novel profiles by the same generalized approach.
Computer Program for Mathematical Modeling and Identification of Hydrodynamic Processes of a Radial Piston Pump
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
Z. Glavcic and R. Petrovic,
2010,
volume 1,
pp. 191-198,
Juni 2010
view abstract
Fundamental basis in developing the radial piston pump presents an experimental research and mathematical modeling
of non stationary high dynamic hydraulic processes in the pump cylinder, discharge space and intake and discharge
pipe line in the function of the action angle of the shaft. Based on the experimental research results and the results of
the mathematical modeling, developing and application of the identification method of unknown parameters of a
mathematical model, the computer program has been developed which enables sufficiently exact determination of some
parameters of working processes of radial piston pumps.
Computer Program for the Design of Hydraulic Machines’ Pumping Set with Internal Involute Gearing
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
D. Slodczyk and J. Stryczek,
2010,
volume 2,
pp. 795-805,
Juni 2010
view abstract
The paper presents an original computer program to aid the design process of hydraulic machines pumping set with
internal involute gearing. The pumping set comprises gears with internal involute gearing which work with
compensation elements. The paper also presents a prototype pumping set designed with the aid of the described
program.
Computer Simulation of the Performance of Digital-Displacement Pump-Motors
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
M. Ehsan and W. H. S. Rampen and S. H. Salter,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 19-24,
November 1996
view abstract
The digital-displacement pump-motor is a hybrid device, which combines reciprocating hydraulics with micro-processor control, creating a highly integrated machine capable of producing variable flow and power. It is based
on the conventional hydraulic piston pump but with actively controlled poppet valves for each cylinder. This allows enabling or disabling on a stroke-by-stroke
basis in any desired sequence. Time-domain modelling of the pump-motor system predicts the performance under variable-demand, variable-speed as well as different control-modes. The advantages of this approach over conventional variable-swash hydraulic machines lie with both the
response speed and the inherent energy efficiency.
CONCEPTION OF MOBILE ROBOT WITH HYDROSTATIC DRIVE STEERING BY PLUS+1 MODULE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
A. Guzowski and A. Sobczyk,
2008,
pp. 466-471,
Juli 2008
view abstract
In the paper concept of remote controlled, mobile robot has been presented. Main goal to solve within project is remote
control of drive system and robot end effectors, taking into consideration position, velocity and force. All mechanisms
of the robot will be driven by high pressure hydraulic system. It will allow using, smaller than electric components for
the same level of power. As a control system for electro hydraulic components, which has been chosen to drive
particular mechanisms, Sauer Danfoss PLUS+1 system will be applied, as a system based on CANBus technology,
suitable to create control system of mobile, and, in next step, autonomous machine. Such thought control system will
enable to test and to use different control algorithms. At the beginning, technical documentation, hydraulic system
scheme and electric control scheme have been elaborated.
CONCEPT OF ACTIVE COUNTERWEIGHT SYSTEM FOR MEDIUM EXCAVATOR
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
A. Gawlik and S. Michałowski,
2008,
pp. 462-465,
Juli 2008
view abstract
The paper presents the concept of kinematics structure and hydraulic system of active counterweight for medium
excavators. Research work is oriented towards saving energy of earth movers which have extra movable counterweight.
This counterweight is used to unload the excavator linkage. The suggested solution is that the hydraulic system of active
counterweight should be connected with the boom standard hydraulic system. The counterweight mechanism is
homothetic to linkage mechanism of the excavator. The homothetic transformation applies to kinematics structure and
the center of mass positions. The conservation of the homothetic transformation provides full static unloading of boom cylinder by the counterweight cylinder pressure. Presented hydraulic system does not change functional properties of
the excavator and allows the operator to shut down the movable counterweight system when it is necessary.
Concerning: Research and Development in Fluid Power Technology
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
W. Backé,
2000,
pp. 9-21,
September 2000
view abstract
As introduction the multidisciplinarity of Fluid Power is pointed out. An evaluation of the topics of
presentations given at six International Conferences on Fluidpower represents an overview of the current
Research and Development activities. Three examples should demonstrate how improvements in Fluidpower
progress slowly but steadily.
Condition monitoring and fault diagnosis for vane pumps using flow ripple measurement
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
M. Yang and K. A. Edge and D. N. Johnston,
2008,
pp. 41-54,
September 2008
view abstract
Vane pumps are simple in principle and can be mass produced inexpensively, making them Well suited to the automotive industry. They also have many other applications, such as in the chemical industry and food industry. A common type of damage to a vane pump is cavitation erosion on the side plates. If this damage is not detected in time, it could cause failure of the pump, which depending on the type of system may have safety implications, and in some cases a high cost from lost production Whilst the system is shut down. This kind of damage is common on other types of pumps such as gear pumps and piston pumps. So a practical method for fault diagnosis of hydraulic pumps is required which does not necessitate removal of a pump from the Working system.
This paper presents a method of detecting and identifying cavitation damage on pump side plates via pump flow ripple. Power steering vane pumps are used for this study, although the principles may also be applicable to other types of vane pump, and indeed to piston and gear pumps. The investigation has been done through measurement and simulation. A numerical model of a vane pump is described, and simulated cavitation damage is introduced into the model. This damage is shown to have a clear effect on the simulated flow ripple. The pump flow ripple has also been measured experimentally using the Secondary Source Method, and artificial damage has been introduced into the pump. The damage is shown to have a clear effect on the measured flow ripple, consistent with the simulation results.
Whilst the secondary source enables the measurement of flow ripple in laboratory conditions, it is generally impracticable for in-situ measurement for condition monitoring. A simplified method for calculation of pump flow ripple from in-situ pump pressure ripple measurements and system impedance is discussed.
Condition Monitoring for Hydraulic and Lubricating Fluids
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
H. Mannebach,
2007,
volume 3,
pp. 317-326,
Mai 2007
view abstract
Friction, wear, leakage and excessive temperatures all leave their impact on hydraulic and lubricating fluids. This impact can manifest itself in the form of particulate or fluid
contamination or fluid degradation as a result of thermal oxidation. In this sense the fluid constitutes a fingerprint of the condition of the complete system. Consequently, the
on-line monitoring of fluid parameters presents an efficient way to predict component failure, achieve longer fluid service life and to implement condition-based or predictive
maintenance procedures. Today, robust and cost effective on-line sensors to measure various fluid properties are available. This paper summarizes sensor principles and
technologies and provides suggestions for sensor installation in hydraulic and lubricating systems.
Condition monitoring of aircraft fuel pumps using pressure ripple measurements
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
N. Johnston and C. Todd,
2010,
pp. 161-174,
September 2010
view abstract
A novel method for estimation of unsteady flowrate using pressure at two or three points along a pipeline is described in this paper. The pressure data are processed using a wave propagation model to determine the unsteady flow. Computer simulations show that the proposed method is effective for unsteady flowrate measurement to a high bandwidth. However, if the pressure values from two transducers are used, inaccuracies exist at certain frequencies when the transducer spacing coincides with multiples of half a wavelength. The accuracy can be improved by adding a third transducer with unequal spacing. The comparison and analysis of two-transducer and three-transducer techniques are investigated through simulation. This method may be applied to real time flowrate measurement, control systems or active noise cancellation systems.
Condition Monitoring of Pneumatic Systems Using Self−Organising Maps
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
A. Zachrison and M. Sethson,
2007,
volume 2,
pp. 407-421,
Mai 2007
view abstract
Automated monitoring of systems is growing in importance as systems become increasingly autonomous and intelligent control is being used to a growing extent. At the same time, component manufacturers’ desire to offer components with embedded condition monitoring systems is also increasing.
This paper discusses one general, adaptive method – the self-organising map, SOM– suitable for such an application. It concerns how to improve interpretation of the fault
classification process by using a combination of outputs from the SOM. The simultaneous detection of both known and unknown faults is discussed.
CONDITION – MONITORING – SYSTEM FOR HYDRAULIC FLUIDS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
C. Riedel,
2008,
pp. 211-218,
Juli 2008
view abstract
This paper illustrates the current findings of the project „Condition-Monitoring-System for hydraulic and transmission
fluids”. Different oil parameters such as humidity, conductivity, dielectricity, viscosity and temperature can be
measured online with a multi-sensor approach that permits a description of the oil condition. By measuring the particle
contamination the fluid can serve as a mirror for the system condition.
At first it is illustrated how the fault diagnosis system pre-processes the sensor signals. Furthermore it evaluates the
current fluid condition on basis of this information automatically and deduces to certain fault scenarios of the system.
Beyond a prediction of fluid ageing by means of limit values and trends of specific physical fluid characteristics the
development of a new approach for improved oil ageing models for the prediction of the life span is conducted.
Data from both test stand experiments and industrial plants is used for validation and verification. Furthermore it is
described how the gathered information can be made available for the operator. For this purpose a human-machine
interface is being developed that displays the information about the system condition in different levels of complexity
with miscellaneous visualisation methods ranging from a simple condition indicator to detailed information.
Construction Machines and Manipulators - Modern Designs and Research Problems
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
A. Sobczyk,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 345-364,
view abstract
No abstract available
Construction of On-Line Monitoring and Fault Diagnosis System for Large Scale Complicated Hydraulic Equipment
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
Z. Jiancheng and Z. Entao and C. Jianwen et al.,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 177-181,
November 1997
view abstract
The working process of a large scale complicated hydraulic equipment is analysed from the function and the principle by means of the method of the bridge of fluid resistance. On this basis, the design of an on-line monitoring and fault diagnosis system for the equipment is introduced in detail. In combination with a practical example of fault diagnosis, the usage of the system is shown. The selection of monitoring signal, learning mechanism and the cooperation between person and computer. These problems related the construction of the on-line monitoring and fault diagnosis system, are also discussed.
Contact Mechanics for Randomly Rough Surfaces with Applications
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
B.N.J. Persson and B. Lorenz,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 315-325,
März 2010
view abstract
When two solids are squeezed together they will in general not make atomic contact everywhere within the nominal (or apparent) contact area. This fact has huge practical implications and must be considered in many technological applications. In this paper we briefly review basic theories of contact mechanics, and consider in detail a recently developed contact mechanics theory.
Containing the cup in the floating cup axial piston machine
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
T. L. van den Brink and P. A. J. Achten,
2006,
pp. 131-145,
September 2006
view abstract
In a floating cup axial piston machine, each piston has its own cuplike cylinder, floating on a barrel plate. A hold down spring prevents these cups from tilting off the barrel plate but allows them to slide over it, along a very small track. This paper will focus on the design of a hold down spring. Friction between the cup and its adjoining parts is studied and found to influence the optimal design of the hold down spring. However, on the machine efficiency the effect of this friction is negligible.
Continuous CMAC and its Application in Identification of Electrohydraulic Servo System
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
S. Wei and H. Hong,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 113-117,
November 1998
view abstract
Based on finite element interpolation method a continuous CMAC (CCMAC) is proposed in this paper, the output of the network can change with its input continuously, the generalization of network is improved, the training speed and identification precision are also improved. The continuous CMAC is used in the system identification of electrohydraulic velocity servo control system, many simulation and experiment results are satisfactory.
Contrapropagating Ultrasonic Flowmeter Using Clad Buffer Rods for High Temperature Measurements
D. R. França and C.-K. Jen, and Y. Ono,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Januar 2011
view abstract
This work proposes clad buffer rods driven by shear transducers as the main building block of contrapropagating ultrasonic flowmeters for high temperature application. It is demonstrated that the superior signal-to-noise ratio exhibited by clad buffer rods (compared with the reported nonclad counterparts) improves precision in transit time measurements, leading to more accurate flow speed determination. In addition, it is shown that clad buffer rods generate specific ultrasonic signals for temperature calibration of flowmeters, allowing temperature variation while still measuring accurately the flow speed. On the basis of these experimental results, a contrapropagating ultrasonic flowmeter was designed and installed in a heater machine for flow speed measurements of hot oil at temperatures near 130°C. For a temperature variation of 3°C, the difference between upstream and downstream ultrasonic transit times, which is proportional to the flow speed at a given temperature, was measured within 1 ns accuracy.
Control and Identification of Vortex Wakes
C. R. Anderson and Y.-C. Chen and J. S. Gibson,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 298-305,
Juni 2000
view abstract
In this paper, control and identification methods for vortex wakes are investigated. The particular problem studied concerns the stabilization of vortices behind a flat plate, using backside suction as an actuator. The flow dynamics are modeled with a discrete vortex method. Feedback control results for a linear PI controller are presented as well as identification results for a class of input/output models that can be used to design more sophisticated controllers.
CONTROL BASED ON NEURAL NETWORK STRATEGY FOR A HYDRAULICALLY DRIVEN PARALLEL MANIPULATOR
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
Y. Liu and H. Handroos,
2006, August 2006
view abstract
The study presents an application of adaptive control to achieve tracking performance of MULTIPOD using neural network. MULTIPOD is a robotic manipulator based on two parallel 3-DOF mechanisms in serial connection. With the capability of mapping all kinds of nonlinear elements from artificial neural network, the neural network acceleration feedback control with constant gain characteristic is embedded with the inner loop line of the position control for the nonlinear dynamic system. The proposed neural network controller is a combination of a proportional controller and a neural network. The neural network is trained on-line. Some results of the performance for the controlled system are given.
Control Concept for Hysteresis Free Behaviour of Proportional Solenoid
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
A. Gadyuchko and F. Bussinger and E. Kallenbach and O. Radler,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 509-522,
März 2010
view abstract
The global aim of the work is a proportional solenoid with an anhysteretic distinct transfer function. This paper shows how the magnetic function Y(i,d) describes the processes in the proportional solenoid considering the influence of the load. Due to a new sensorless measuring approach this function can be used to define the reversal and positioning errors appearing while operation of proportional valves. This measuring information allows to adapt hysteresis compensation algorithms and as a result to improve the control quality.
Control Design for Relative Stability in a PWM-Controlled Pneumatic System
Eric J. Barth and Jianlong Zhang and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 504-508,
September 2003
view abstract
This paper presents a control design methodology that provides a prescribed degree of stability robustness for plants characterized by discontinuous (i.e., switching) dynamics. The proposed control methodology transforms a discontinuous switching model into a linear continuous equivalent model, so that loop-shaping methods may be utilized to provide a prescribed degree of stability robustness. The approach is specifically targeted at pneumatically actuated servo systems that are controlled by solenoid valves and do not incorporate pressure sensors. Experimental demonstration of the approach validates model equivalence and demonstrates good tracking performance.
Controllability and Observability Analysis of the Liquid Water Distribution Inside the Gas Diffusion Layer of a Unit Fuel Cell Model
Buz A. McCain and Anna G. Stefanopoulou and Jason B. Siegel,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
November 2010
view abstract
We analyze the controllability and observability (C/O) of the liquid water distribution in the gas diffusion layer (GDL) of a polymer electrolyte membrane fuel cell (PEMFC) using a one-dimensional channel-to-channel unit fuel cell model. This modeling domain is sufficient to illustrate the control objectives and analysis techniques but requires further development for stack level modeling. A comparison is made between first-principles-based numeric and reduced-order semi-analytic models with emphasis on the effects of model reduction on their analyses. The numeric model is a partial differential equation based model approximated by difference equations, including both channels and both GDLs of a PEMFC. The reduced model uses a semi-analytic solution method, which is a combination of analytic and numeric solutions, gaining physical intuition at lower computational cost. The C/O analysis is based on linearizations around three critical operating points. The results indicate that stabilizability of the anode liquid water states and, hence, management of anode water flooding is possible. If the channel water mass can be controlled to a constant value, then the GDL liquid distribution will be stable (McCain et al., 2007, “A Multi-Component Spatially-Distributed Model of Two-Phase Flow for Estimation and Control of Fuel Cell Water Dynamics,” Proceedings of the 46th IEEE Conference on Decision and Control, pp. 584–589). Further, it will be shown that if the channel liquid water mass can be brought to zero, controllability of the GDL liquid modes will be obtained. Additionally, this study will indicate the input(s) best suited to obtain this control objective and the output(s) required.
CONTROLLED VALVE PLATE IN BENT AXIS HYDRAULIC MOTORS
A. V. Khrapak,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 65-74,
August 2001
view abstract
The research object of the given work is the bent axis hydraulic motor (BAHM). In this paper the interaction of the
rotating cylinder block and motionless valve plate (VP) is investigated. The research aims are focused on evaluation of
the experimental and theoretical data of the VP friction torque and hydraulic fluid leakages. The up-to-date technologies
require the BAHM components to be more reliable and durable. On the way of BAHM design improvement, the new
VP is introduced in this paper. The new design features provide more reliable fluid lubrication in the gap between VP
and cylinder block and increase the durability of the piston cylinder assembly in heavy operation modes. The laboratory
tests proved the efficiency of the new VP design.
Controlling a conventional LS-pump based on electrically measured LS-pressure
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
T. O. Andersen and H. C. Pedersen and M. R. Hansen,
2008,
pp. 529-542,
September 2008
view abstract
As a result of the increasing use of sensors in mobile hydraulic equipment, the need for hydraulic pilot lines is decreasing, being replaced by electrical wiring and electrically controllable components. For controlling some of the existing hydraulic components there are, however, still a need for being able to generate a hydraulic pilot pressure. In this paper controlling a hydraulic variable pump is considered. The LS-pressure is measured electrically and the hydraulic pilot pressure is generated using a small spool valve. From a control point of view there are two approaches for controlling this system, by either generating a copy of the LS-pressure, the LS-pressure being the output, or letting the output be the pump pressure. The focus of the current paper is on the controller design based on the first approach. Specifically a controlled leakage flow is used to avoid the need for a switching control structure.
CONTROL OF A PNEUMATIC SERVOSYSTEM USING FUZZY LOGIC
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
H. Moreno Llagostera,
2000,
pp. 189-201,
September 2000
view abstract
The servodrive analyzed here consists on a large stroke actuator of 2 meters, activated by a flow proportional
valve. The aim of the Ph.D. is to achieve a successful control of the actuator despite it having big chambers,
which has a big influence on the system response, owing to the air compressibility. For the experimental study, a
test bench has been built and a magnetorrestrictive sensor of displacement is used in order to close the loop.
Before starting the control of the system and in order to know how the pneumatic servo drive reacts, the interaction
of the actuator and valve set has been studied by means of Bond Graph technique.
At first, the PID control was applied in pneumatic servodrives, after seeing its several problems, state control
algorithm started to be applied. The state loop control algorithm reaches a good result, however in cases where
a system parameter changes it is necessary to retune the state variable gains (position, velocity and acceleration),
above all in this particular case. It is here where Fuzzy Logic reasoning could be used.
CONTROL OF A SERVOPNEUMATIC DRIVE WITH FRICTION COMPENSATION
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
E. A. Perondi and R. Guenther,
2000,
pp. 117-127,
September 2000
view abstract
In this paper the problem of pneumatic positioning system in presence of friction is addressed. The
standard controllers deficiencies when applied to a servopneumatic drive were verified. The main detected
problems consist of gains tuning difficulties, robustness lack to payload variations and great sensibility to the
friction effects. To overcome the problems of the robustness lack and gains tuning difficulties it was designed
and implemented a variable structure controller. Besides, to deal with the friction effects, a compensation
scheme was implemented based on a nonlinear friction force states observer. The given results were considered
promising, with precision of ±0,2 mm for positioning problems and of ±2,5 mm for path tracking tasks.
Control of Deep-Hysteresis Aeroengine Compressors
Hsin-Hsiung Wang and Miroslav Krstic and Michael Larsen,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 140-152,
März 2000
view abstract
Frequencies of higher-order modes of fluid dynamic phenomena participating in aeroengine compressor instabilities far exceed the bandwidth of available (affordable) actuators. For this reason, most of the heretofore experimentally validated control designs for aeroengine compressors have been via low-order models—specifically, via the famous Moore-Greitzer cubic model (MG3). While MG3 provides a good qualitative description of open-loop dynamic behavior, it does not capture the main difficulties for control design. In particular, it fails to exhibit the so-called "right-skew" property which distinguishes the deep hysteresis observed on high-performance axial compressors from a small hysteresis present in the MG3 model. In this paper we study fundamental feedback control problems associated with deep-hysteresis compressors. We first derive a parametrization of the MG3 model which exhibits the right skew property. Our approach is based on representing the compressor characteristic as a convex combination of a usual cubic polynomial and a nonpolynomial term carefully chosen so that an entire family of right-skew compressors can be spanned using a single parameter epsilon. Then we develop a family of controllers which are applicable not only to the particular parametrization, but to general Moore-Greitzer type models with arbitrary compressor characteristics. For each of our controllers we show that it achieves a supercritical (soft) bifurcation, that is, instead of an abrupt drop into rotating stall, it guarantees a gentle descent with a small stall amplitude. Two of the controllers have novel, simple, sensing requirements: one employs only the measurement of pressure rise and rotating stall amplitude, while the other uses only pressure rise and the mass flow rate (1D sensing). Some of the controllers which show excellent results for the MG3 model fail on the deep-hysteresis compressor model, thus justifying our focus on deep-hysteresis compressors. Our results also confirm experimentally observed difficulties for control of compressors that have a high value of Greitzer's B parameter. We address another key issue for control of rotating stall and surge—the limited actuator bandwidth—which is critical because even the fastest control valves are often too slow compared to the rates of compressor instabilities. Our conditions show an interesting trade-off: as the actuator bandwidth decreases, the sensing requirements become more demanding. Finally, we go on to disprove a general conjecture in the compressor control community that the feedback of mass flow rate, known to be beneficial for shallow-hysteresis compressors, is also beneficial for deep-hysteresis compressors.
CONTROL OF HYDROSTATIC MULTISOURCES POWER SYSTEMS IN TERM OF SELECTED CRITERIA
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
H. Chrostowski and K. Kedzia,
2002, Juli 2002
view abstract
The analysis of working performance parameter of the multisource hydrostatic system was assumed. The system
consists of: a diesel engine Perkins AD3 152 UR, multi-piston axial hydrostatic machines having varied pump,
a hydrostatic motor unitary volume, an electro-hydraulic amplifier (AW- 10)- which is used to transform electric
control signal from computer, to mechanical signal, which is used to steering the hydrostatic motor and pump IT3, and
a gas-hydraulic accumulator- filled with nitrogen.
Kinetostatic method, which was used to calculate controlling functions of the multisources system, it gives
opportunity to steer the system taking into account the selected conditions such as: minimal fuel consumption Ge (highways,
country side zones) or exhaust gasses emission: CO, NOx, range of smokiness to atmosphere (towns, mines). As
a result of the kinetostatic method we received:
• the point of the stable work of the IC engine (primary source of energy),
• establishing controlling functions of the hydrostatic units (εp, εsh) in given load cyclorama,
• determining the initial parameters (capacity v0 and energy EA) of hydraulic accumulator (secondary source of
energy)
Control of Interface of HIL Simulator for Hydromechanical Machines
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Eskola and P. Pedersen and H. Handroos,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 18-22,
April 2005
view abstract
The study deals with control of interface of hardware-in-the-loop-simulator for hydro-mechanical machines. In the proposed form a real-time simulator of hydraulic system can be connected with a mechanical hardware by flow-pressure interface realized by high-bandwidth Servo or proportional valves with flow feedback control. A flow control method based on inverse valve model and flow feedback with PI-controller is proposed and studied in z-domain. Model in z-domain for a simple complete HIL-simulator is derived and utilized in analyzing the properties of the proposed controller.
CONTROL OF MOBILE HYDRAULIC CRANES
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
M. E. Münzer,
2000,
pp. 475-483,
September 2000
view abstract
The goal of the thesis described in this paper is to improve the control of mobile hydraulic cranes. The thesis is
split into five parts: a requirements analysis, an analysis of the current systems and their problems, an analysis
of different possibilities for system topologies, development of a new control system for the near future based on
electro-hydraulic separate meter in / separate meter out valves, and finally an analysis of more advanced and
complex solutions which can be applied in the more distant future. The work of the thesis will be done in cooperation
with industry so the thesis will have more of an industrial focus than a purely theoretical focus.
Control of vane pump delivery by the deadbeat controller
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
W. Czyzycki and E. Lisowski,
2004,
pp. 67-75,
Juni 2004
view abstract
In the paper will be presented results of theoretical research of controller deadbeat type in application to
control vane pump delivery. These controllers might be realized in digital control technology. This paper will
also present designing of such regulator by the use of computer simulation software. Simulations of the
deadbeat controller will also be carried out so as to assess controller parameters. This subject is a part of
the work dealt with vane pump delivery control. As it is known main features of vane pumps are: silent
running, short time of adjusting, relatively low cost and small dimensions. Application of microprocessor
control increase possibilities of those pumps in area of adopting pump delivery to actual system demand at
minimal energy losses. Main expected advantageous of new controller generation are: quick change of
delivery and pressure and stable operation. Results of simulations will show what possibilities deadbeat
controller has.
Control of Water Turbine Guide Apparatus by Use of Water Hydraulic Actuator
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
P. Walczak and A. Sobczyk,
2010,
volume 2,
pp. 819-826,
Juni 2010
view abstract
This article presents development work on creating the model of the water hydraulic control system for water turbine
guide apparatus control. Complete was added to hydraulic system model of relief valve and piston pump. Also some
data from typical water turbine control system was taken into account. Therefore presented model
of control system is closer to reality for small water-power plant.
The test of describing the mass of cylinder - guide apparatus - blade was conducted. Reduced mass of such mechanism
is a function of cylinder position. Paper shows proposal to implement turbine rpm control which will be responsible for
increasing or decreasing of water flow on turbine blades to keep its set velocity. It should allow omitting electronic
system i.e. based on PID or fuzzy logic controller which are used today to steering and monitoring turbines of waterpower
plant. This research has big meaning in development of small water turbine
Control-Oriented Modeling of Transcritical Vapor Compression Systems
Bryan P. Rasmussen and Andrew G. Alleyne,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 54-64,
März 2004
view abstract
This paper presents a methodology for developing a low order dynamic model of a transcritical air-conditioning system, specifically suited for multivariable controller design. An 11th-order nonlinear dynamic model of the system is derived using first principles. Analysis indicates that the system exhibits multiple time scale behavior, and that model reduction is appropriate. Model reduction using singular perturbation techniques yields physical insight as to which physical phenomena are relatively fast/slow, and a 5th-order dynamic model appropriate for multivariable controller design. Although all results shown are for a transcritical cycle, the methodology presented can easily be extended to subcritical cycles.
Control Strategies for Load-Sensing in Mobile Machinery
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Helduser and M. Djurovic,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 32-42,
April 2005
view abstract
The paper deals with design and investigation of improved electrohydraulic Load-Sensing systems. They combine the advantages of the conventional hydromechanical system with good controllability and high user-friendliness of electrohydraulic systems. Standard mobile components can be used in practice.
Design and optimization of control algorithms have been performed for the system solutions with the highest grade of energy saving potential. The results of investigation by means of simulation and on a test rig prove the expected increase of system efficiency, independent of the operating point, as well as improved dynamic characteristics of the new systems compared to the conventional Load-Sensing concept.
Control Strategy for Water Hydraulic Driven Hybrid Parallel Robot
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
H. Wu and H. Handroos,
2010,
pp. 339-351,
September 2010
view abstract
This paper presents a novel mobile parallel robot, which is able to carry out the welding and machining processes from inside the international thermonuclear experimental reactor
(ITER) vacuum vessel. The kinematic design of the robot has been optimized for the ITER access. To improve the performance of the robot, a hybrid control system is designed and an advanced controller has been developed, master-slave control for tracking motion is used to avoid un-synchronous motion of two drive motors, and the pressure feedback together with a high-pass filter is applied to reduce vibration in the machining process.
Control System Development for the Water Hydraulic 6−DOF Motion Platform
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
M. Rokala and T. Palonen and H. Sairiala and K. T. Koskinen,
2007,
volume 1,
pp. 89-102,
Mai 2007
view abstract
Stewart platform is commonly used 6-DOF (Degree Of Freedom) motion platform in the driving and flight simulators. There is a research going on for using water hydraulic actuators in Stewart platform in Institute of Hydraulics and Automation. This paper describes the control system of the first water hydraulic Stewart platform.
The motion platform has six water hydraulic cylinders which are controlled by proportional directional valves. The valves are controlled by MathWorks xPC Target real-time software. The measurement and control is realized with standard PC with two
analogue input cards and one analogue output card. Control signal is calculated from measured information and from the reference position of the cylinders. Cylinder position, spool position and cylinder pressures are measured. Reference position for the cylinders is calculated through inverse parallel kinematics when the desired position and orientation of the top plate is known.
The real-time simulator with the motion platform requires fast and accurate response from the motion platform. The controlling of the valves is the most important part of the tuning because of the valves is the slowest part of the system. In this paper the measurement results of the platform responses is presented.
CONTROL SYSTEM OF DOUBLE ACTING SINGLE ENDED CYLINDER SIMULATION – CONCEPT OF WATER TURBINE GUIDE APPARATUS CONTROL
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Walczak and A. Sobczyk,
2008,
pp. 524-533,
Juli 2008
view abstract
This article is introductory elaboration of the theoretical model of the hydraulic control system of water turbine guide
apparatus control. Main goal of proposed hydraulic system configuration is control, in future, increasing or decreasing
of water flow on water turbine blades, to keep its constants velocity by pressure feedback, which will control position of
directional control valve slider .
Coordinated Position Control of Five Hydraulic Cylinders Based on High Speed On/Off Valves
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
J. Pan and G. Shi and P. Yang,
2010,
volume 1,
pp. 115-125,
Juni 2010
view abstract
In this paper, a platform with five hydraulic cylinders employing high speed on/off valves for the position control is
introduced. The high speed on/off valve is used more and more during the recent years for their merits compared to the
servo-valve. The valve which is a typical nonlinear system including electro-magnetic, mechanical and fluid subsystems
can be cheated as black-box to which the frequency and duty cycle of the input PWM (Pulse Width Modulation) signal
are main parameters. Therefore, a radical basis functions (RBF) network which has two inputs and one output is
developed to identify the model of the valve. Because of the nonlinear of the system, the adaptive PID control method is
adopted to achieve desired performance. In order to validate the model and the control strategy of the system, the
simulation and the experiments are carried out. From the simulation and the experimental results, the coordinated
position control system can do well with the identified model.
Coupled Simulation for the Virtual Product Development of Electro-Hydraulic Valves
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
M. Fiedler and S. Helduser and D. Wehner,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 431-444,
März 2010
view abstract
Holistic numerical simulation is an important tool for designing and testing mechatronic systems. Coupling the programs for system simulation and the calculation of fields allows utilisation of the benefits of both simulation strategies. These are the high resolution of physical effects in the field simulator, on the one hand, and the fast dynamic simulation of various domains in the system simulator on the other hand. This allows a virtual conceptual design of valves which only uses mathematical-physical relations, geometric dimensions and material data. These virtual prototypes can be used to investigate the interactions between subsystems and for static and dynamic performance estimates.
Coupling Simulations of Hydraulic Systems with Characteristic Method and CFD
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Q. Chen and B. Stoffel and L. Quan,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 543-547,
April 2005
view abstract
In recent years, with the development of personal computers of the large-capacity and rapid computation, numerical simulation with CFD (Computational Fluid Dynamics) has been becoming broadly applied to analyze the inside flow processes of the hydraulic components in fluid technology. The main aim of this paper is the investigation of coupling simulation of hydraulic systems, which mainly consist of hydraulic pipelines, pressure limiting valve, throttle, etc., including offline and online coupling. To do so, two methods are used: one of the simplified simulation methods for hydraulic systems, namely, characteristic method, and flow simulation method - CFD. The simulations of the inside flow of a measuring orifice and specially the investigations of cavitation phenomenon in a pressure limiting valve, as well as the oscillation of the cone of this valve are complemented with CFD code FLUENT, the other parts of computation for the studied systems are carried out through Matlab/Simulink by means of one-dimensional characteristic method. The online coupling simulation is realized using two personal computers and the necessary transfer of the signal files is accomplished per TCP/IP. The simulation results of offline coupling represent that the averaged flow velocity at the outlet of the measuring orifice from Fluent is 8.58 % larger than the value from Matlab/Simulink, and there is a phase difference of 80° between these simulation results. The study of online coupling simulation shows that vapor volume fraction changes dynamically during the motion of the cone. When the gap between the seat and the cone of the pressure limiting valve equals 1.8e-4 m, the value of vapor volume fraction reaches 65 %, whereas, when the gap increases to 2.4e-4 m, the value of vapor volume fraction reduces to 0.26. The calculation results of coupling simulation prove sufficiently the validity of the applied coupling principle.
Cross utilizing degree of freedoms of boom in energy saving concept
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
T. Virvalo and J. Seppälä,
2006,
pp. 31-43,
September 2006
view abstract
An important topic in R&D of mobile machines, for instance forest machines, is the improving of energy utilization. The efficiency or energy utilization is still very poor. Possibilities to utilize the gravitational force influencing one or two degree of freedom in some other degree of freedom are studied in a forward loader case. The basic idea studied is to use the outflow of the lift cylinder to drive the telescope cylinder. The outflow is used directly or via the accumulator. According to simulation quite remarkable reduce of energy consumption can be achieved.
Current Trends and New Applications in Motion and Positioning Control Solutions for Earthmoving and Construction Equipment
Developments in Fluid Power Control of Machinery and Manipulators - 2nd International Scientific Forum, Cracow, Poland
ISBN: 83-86219-71-8,
S. Michalowski and M. Skibniewski and A. Sobczyk,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 216-221,
Juni 2000
view abstract
Contemporary construction works frequently require application of machines and equipment performing more complex operations to produce the designed shape of excavation or surface profile. In construction works, precise
operation and positioning of the manipulator end-effector is important. An example of automation is the positioning of a concrete or asphalt paver deck in road works. Manual control of such works is difficult and requires highly skilled
operators. Modern machines are equipped with tool position control Systems, which allow automation of the machine operation [6,7,8]. In most cases hydraulic actuators are implemented in the control system. Practically, position of an
operating tool is defined in a local system of co-ordinates connected with the machine chassis. However, taking into consideration the work being perfornied or
positioning motions it is more important to refer the tool position to the global system of co-ordinates connected, for instance, with the terrain.
'CYCLOIDAL GEAR MACHINES' OPTIMAL DESIGNING OF INNER CHANNELS IN GEROTOR PUMPS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Antoniak and J. Stryczek,
2008,
pp. 135-142,
Juli 2008
view abstract
The authors of the paper present application of the theoretical model of the flow processes in the gerotor pump for
optimization of the gerotor pumps' channels and clearances. To do this, they developed and used a special computer
program, called 'Cycloidal Gear Machines', implementing the model.
DAMPING AUGMENTATION OF FLEXIBLE STRUCTURES — A ROBUST STATE SPACE APPROACH—
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
U. B. Carl and M. H. Gojny,
2000,
pp. 417-434,
September 2000
view abstract
The present paper addresses the regulation of weakly damped aeroelastic wing structures by means of the primary
flight controls (PFC). Synthesizing a sufficient low–order linear multi model system of the aggregate aeroservoelastic
plant requires the design of a robust state feedback. This ensures a remarkably augmented damping ratio in
comparison with the original aeroelastic system. Moreover, the influence of the actuation system performance on
the aeroservoelastic damping augmentation feedback is investigated. The suitability of the resulting controller is
verified by simulation as well as validated by real tests.
DATA MINING ENHANCEMENT IN MODEL BASED FAULT CLASSIFIERS OF A HYDRAULIC CYLINDER DRIVE
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
V. Vidqvist and M. Hiirsalmi,
2006,
volume 1,
pp. 325-330,
Juni 2006
view abstract
This paper covers a subject how to create better classifiers to detect different failures of a hydraulic cylinder drive.
Fault models with variation are added to the system model and output of combined models is used to train different
classifiers. Classifier efficiency can be enhanced if a compact set of feature extractors is discovered to identify key
differences between the time series prevailing during the different fault conditions. In an example case feature
extractors and classifiers were created for a test case by using visual data mining to learn about the measurements and
to discover the differences between the measurement signals. The results show a clear improvement on the
classification results previously achieved by using a different set of feature extractors called statistical window.
Decentralized Coordinated Motion Control of Two Hydraulic Actuators Handling a Common Object
Mark Karpenko and Nariman Sepehri and John Anderson,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 729-741,
September 2007
view abstract
In this paper, reinforcement learning is applied to coordinate, in a decentralized fashion, the motions of a pair of hydraulic actuators whose task is to firmly hold and move an object along a specified trajectory under conventional position control. The learning goal is to reduce the interaction forces acting on the object that arise due to inevitable positioning errors resulting from the imperfect closed-loop actuator dynamics. Each actuator is therefore outfitted with a reinforcement learning neural network that modifies a centrally planned formation constrained position trajectory in response to the locally measured interaction force. It is shown that the actuators, which form a multiagent learning system, can learn decentralized control strategies that reduce the object interaction forces and thus greatly improve their coordination on the manipulation task. However, the problem of credit assignment, a common difficulty in multiagent learning systems, prevents the actuators from learning control strategies where each actuator contributes equally to reducing the interaction force. This problem is resolved in this paper via the periodic communication of limited local state information between the reinforcement learning actuators. Using both simulations and experiments, this paper examines some of the issues pertaining to learning in dynamic multiagent environments and establishes reinforcement learning as a potential technique for coordinating several nonlinear hydraulic manipulators performing a common task.
DERIVATION OF DESIGN REQUIREMENTS FOR OPTIMIZATION OF A HIGH PERFORMANCE HYDROSTATIC ACTUATION SYSTEM
S. R. Habibi and G. Singh,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 11-27,
Oktober 2000
view abstract
The competitive global market dictates greater quality of product models produced at lower cost and in shorter duration.
During the past two decades, the efficiency of production processes and the quality of products have been differentiating
factors in establishing competitive advantage in mature industries such as fluid power. The survival of such industries
is increasingly dependent on their ability of optimizing their component characteristics as well as integrating
these in complex subsystems. Reduction of cost of poor quality is thus critical. This cost often originates from inadequate
or sub-optimal design requirements. Mature industries involved in the design and production of complex systems,
have recognized the importance of design requirements definition in reducing cost and increasing profitability.
This paper considers linking of system requirements to design parameters for a high performance actuation system
referred to as the Electro Hydraulic Actuator (EHA). EHA is based on the hydrostatic actuation concept. It has been
prototyped and has demonstrated a very high level of performance. The mathematical model of EHA is reviewed and
used for linking its performance to its design parameters through a set of mathematical functions. The actual and expected performances of the prototype are compared in order to validate the proposed mathematical functions and an
improved design is proposed.
Design and Analysis of a New Underwater Robot for Autonomous Cleaning Water Pool
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Li and K. M. Lo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 869-872,
April 2005
view abstract
An underwater robot is developed for cleaning the water pool of Macau Water Company. A prototype of underwater robot is designed to meet the needs of cleaning job. The cleaning job can be classified into two main parts: bottom cleaning and side-wall cleaning. Most of the pool cleaning robots available in the market is typically a mobile robot. But a mobile robot alone cannot cleanse up some areas inside the water pool, such as the comer areas and the surface above the water level. Hence an underwater vehicle-manipulator system (UVMS) developed in this paper can tackle the cleaning issues efficiently.
Design and Control of Chemomuscle: A Liquid-Propellant-Powered Muscle Actuation System
Xiangrong Shen and Daniel Christ,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
März 2011
view abstract
This paper describes the design and control of a new chemomuscle actuation system for robotic systems, especially the mobile systems inspired by biological principles. Developed based on the pneumatic artificial muscle, a chemomuscle actuation system features a high power density, as well as similar characteristics to the biological muscles. Furthermore, by introducing monopropellant (a special type of liquid fuel) as the energy storage media, the chemomuscle system leverages the high energy density of liquid fuel and provides a compact form of high-pressure gas supply with a simple structure. The introduction of monopropellant addresses the limitation of pneumatic supply on mobile devices and thus is expected to facilitate the future application of artificial muscle on biorobotic systems. In this paper, the design of a chemomuscle actuation system is presented, as well as a robust controller design that provides effective control for this highly nonlinear system. To demonstrate the proposed chemomuscle actuation system, an experimental prototype is constructed, on which the proposed control algorithm provides good tracking performance.
Design and Dynamic Analysis of High Speed on/off Poppet Valves for Digital Pump/Motors
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
G. J. Wilfong and M. A. Batdorff and J. H. Lumkes,
2010,
volume 1,
pp. 259-269,
Juni 2010
view abstract
High speed on/off valves are an important part of new technology within fluid power. An improved modeling tool has
been developed to quickly and accurately simulate nearly any axisymmetric seat type valve having electromagnetic
actuators. The developed model uses a lumped parameter coupled multi domain solving method to simulate fluidic,
electromagnetic, and mechanical interactions. By varying parameters within the model, the dynamics and response of
the valve can be optimized and the results used to design and fabricate prototype valves. This is demonstrated by
simultaneously varying poppet and armature spring pretensions with the objective of minimizing valve transition time.
Future work toward improving the model will be to add equation sets that accurately capture magnetic fringing and
leakage.
DESIGN AND EXPERIMENTAL EVALUATION OF POSITION CONTROLLERS FOR HYDRAULIC ACTUATORS: BACKSTEPPING AND LQR-2DOF CONTROLLERS
A. L. D. Franco and E. R. De Pieri and E. B. Castelan et al.,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 39-48,
November 2004
view abstract
In this paper the problem of experimental control of hydraulic actuators is considered. To deal with mechanical and
hydraulic uncertainties two different controllers are synthesized: a backstepping controller and a LQR-2DOF controller.
Experimental results of both implementations are analyzed in the context of practical difficulties, mainly the measurement
of acceleration. These results illustrate the main features of these controllers when applied on a hydraulic actuator.
Design and Fabrication of Actuation System Using Functional Fluid
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
Y. Tanaka and J. Ziegelheim and S. Yokota,
2006,
pp. 218-228,
Mai 2006
view abstract
Our research aims at the establishment of design and fabrication to perform
miniaturization, high accumulation and high densification by integrating micro fluid power
system. Fluid power actuation system has a great potential to realize large output power
density comparing to the conventional actuation system under the microscopic environment.
In difficult assembly of mechanical elements, a stereolithography method is used to form the
entire micro fluid power systems in all-in-one design including actuators, pumps and valves.
Our final goal is to develop a new micro fluid power system fabricated by the
stereolithography. In this report, prototype models based on a bourdon type actuator of micro
fluid power devices are fabricated and experimentally investigated. Functional fluid ECF
(Electro-Conjugate Fluid) is also used to be pumping function for the pump module of the
fluid power actuation system. The ECF occurs the jet flow that is impressed high electrical
voltage of direct from a positive electrode to a negative electrode inserted into the fluid. The
fluid power source using the ECF can be embedded in the main body of the fluid power
systems and can be effective as driving source of the actuator. These fabricated parts such as
actuators and pumps are able to contribute on one single-chip, it may realize to the
simplification of the assembly process. Some problems regarding design, fabrication and
assembly of micro fluid power system are discussed.
It is experimentally verified that the actuator has performed by using the functional fluid
power. Moreover the ECF pump is a powerful source to supply necessary power to the
actuator for the fluid power system. The stereolithography method to fabricate the actuator is
the unique technique to integrate and miniaturize some complex parts under the microscopic
environment. It is suitable principle for the actuator to deform elastically materials without
mechanical moving parts. It is clarified for all-in-one design unit consisting of the actuators
and the pump module to use the stereolithography for fabrication.
Design and hybrid control of the pneumatic force-feedback systems for Arm-Exoskeleton by using on/off valve
C. Ying and Z. Jia-fan and Y. Can-jun and N. Bin,
In Mechatronics,
2007,
volume 17,
pp. 325-335,
view abstract
This article models a pneumatic force-feedback system consisting of the double-acting cylinder and a set of high-speed on-off valves, and its fuzzy controller in order to provide an insight into pneumatic system design and force-feedback control requirements of the Arm-Exoskeleton, which is applied in robot-teleoperation and robotics. In modeling, effects of nonlinear flow through the valves, air compressibility in cylinder chambers, and time delay and attenuation of the pressure input in the connecting tubes are considered. Based on this mathematical model, the hybrid fuzzy control method for the precise force-feedback control is proposed and the fuzzy controllers are realized with the Mega8 MCUs as the units of the distributed control system in the Arm-Exoskeleton. At last a series of experiments validated the models and control method.
Design and implementation of a water hydraulic 6-DOF motion platform for real-time simulators
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
T. Palonen and M. Rokala and H. Sairiala and J. Uusi-Heikkilä and M. Hyvönen and K. T. Koskinen,
2006,
pp. 251-264,
September 2006
view abstract
This paper indicates the design and implementation of 6-DOF water hydraulic Stewart platform. It deals with adapting the motion platform to water hydraulics and control of the platform, specifying parts to be studied in more detail.
Four different washout filters for creating motion are studied in simulation model and validated with a test bench with one valve-cylinder pair. Mechanical construction of the platform has been started. Real-time simulators with motion platform demand fast and accurate response for valves and a good controller, since phase delays and fluctuations in the platform motion can cause motion sickness.
Design and Implementation of Energy Saving Digital Hydraulic Control System
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
M. Linjama and M. Huova and P. Boström and A. Laamanen and L. Siivonen,
2007,
volume 2,
pp. 341-359,
Mai 2007
view abstract
Digital Hydraulics is a recently developed alternative for traditional control with servo or proportional valves. The key principle is to use parallel-connected two-way on/off
valves together with intelligent control. This paper studies the energy efficiency of a high inertia cylinder drive. A valve manifold with 4×5 two-way screw-in cartridge valves is used to implement digital hydraulic control of the cylinder. A cost function based control solution is used for online minimization of power losses. Different loading conditions are analyzed and it is shown that the differential connection is essential in reduction of power losses. Switching logic between different flow modes is also studied. Implementation of these ideas requires complex control system. In order to ensure that control system functions as intended, modern techniques for software design and validation (Simulink/Stateflow) are used. The main result of the paper is that energy efficient, cavitation free and high-quality motion control is possible with rather slow response on/off valves. Experimental results with different loads demonstrate 36 percent energy saving in lift-and-lower movements, when compared to traditional loadsensing system.
Design and Mathematical Modelling of High Frequency Hydraulic Switching Valves Driven by Parametrically Excited Structures
Extended Abstracts of Developments in Fluid Power Control of Machinery and Manipulators, Cracow, Poland
M. Garstenauer and R. Scheidl,
1998,
pp. 92-95,
Juni 1998
view abstract
The operating principle of a new type of switching valve is presented. A mathematical model and design issues for first prototypes are discussed.
Design and optimisation of a novel hydraulic free piston engine with liquid-propellant-power
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
H. Ren and H. Xie and H. Yang,
2008,
pp. 341-353,
September 2008
view abstract
This paper describes a new design of a hydraulic free piston engine for human scale power systems. The piston assembly is driven by the energy released by the decomposition of the high test hydrogen peroxide (HTP) through the catalyst. The elimination of the starter, air/fuel mixing and ignition enables a compact and reliable design. Incorporating two 2/2 exhaust valves to discharge the exhaust gas after the power process allows a higher and stable performance. This paper discusses the effect of the design and structural parameters’ on the output and the conversion efficiency of the HTP. Especially, the performance of the 2/2 exhaust valve plays an important role on the frequency, output and gas pressure of the engine. The ragone plot is used to evaluate the engine with the exhaust valves and without the valves (natural exhaust system). The theoretical analysis and the simulation results prove that the engine with the exhaust valves has higher output and stable performance.
Design and Optimization of a Hydraulic Hybrid System Using Multistroke Radial Piston Pump/Motor
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
Y. Brunel and M. Bonis and P. Breitkopf and C. Vayssade and G. Lemaire,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 89-101,
März 2010
view abstract
This paper focuses on the optimization of a parallel hydraulic hybrid system with energy regeneration through fixed or discrete variable displacement motors. First, an optimal path for the main transmission is found. Then, the activation of the energy regeneration system is managed to minimize the global fuel consumption of the vehicle. The components’ models are presented in the first section, and the optimization process is then discussed.
Design and Performance Characterization of a Vane Motor Hydraulic Pump
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
J. Mitchell and M. Goldfarb,
2010,
volume 1,
pp. 331-338,
Juni 2010
view abstract
This paper describes progress towards the development of a compact hydraulic power supply for self-powered humanscale
and sub-human-scale hydraulically actuated machines. The proposed power supply consists of a hydrogen
peroxide powered vane motor coupled to a fixed-displacement piston pump. Current progress includes design,
fabrication, and testing of the hydrogen peroxide powered vane motor. This paper describes the design and
performance characterization of that motor. Future work involves coupling the motor with a small-scale piston pump.
Design of the motor/pump combination is described also.
DESIGN AND SENSITIVITY ANALYSIS OF A SINGLE-STAGE ELECTRO-HYDRAULIC SERVOVALVE
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
S. Mookherjee,
2000,
pp. 71-88,
September 2000
view abstract
An Electro-Hydraulic Servovalve is an essential item of servomechanism where fast speed of response, high
power output and working fidelity are necessary. Two major components of the present single-stage valve are a
spool valve and a linear force-motor. The present work includes lumped and chiefly one-dimensional, non-linear
field modelling of hydraulic fluid in the spool valve and magnetic flux in the motor. Computer aided design and
sensitivity analyses of static performance have been carried out. In the sensitivity analysis, effects of radial
clearance, port lap conditions, mismatch in the areas of the tractive air-gaps and port geometry on valve performance
have been studied.
Design and Simulation Study of the Measuring Device for Hydraulic Oil Bulk Modulus
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
J. Wang and G. Gong and H. Yang,
2007,
volume 2,
pp. 401-406,
Mai 2007
view abstract
In order to get the bulk modulus of hydraulic oil, a bulk-modulus measuring device has been designed according to the definition of the bulk modulus. The measuring is on-line and automatic operation. Some previous problems of the measurement of bulk modulus have been resolved in this design. The simulation study has been carried out using the simulator of AMESim. The results show that the structure parameters of the device and the hydraulic parameters of the testing system are set properly. The measured value of the bulk modulus of hydraulic oil is nearly equal to the theoretical value.
Design and Validation of Digital Controllers for Hydraulics Systems
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
P. Boström and M. Linjama and L. Morel and L. Siivonen and M. Waldén,
2007,
volume 1,
pp. 227-241,
Mai 2007
view abstract
In order to increase the flexibility and performance of hydraulically actuated machines there is a demand for more intelligent controllers. This leads to a rapid increase in
complexity of the control systems. To manage the complexity and to ensure reliability of these systems, adequate software development methods are needed. In this work, we propose a methodology for structured design of digital hydraulics controllers in Simulink/Stateflow. A model architecture based on mode-automata is introduced to separate control and data processing. Furthermore, design by contract is advocated as
a method for system development. The contracts can be used to mathematically reason about correctness of Simulink/Stateflow models and thereby increase the safety and reliability of the developed systems. The usefulness of these concepts are demonstrated on a larger case study from the area of digital hydraulics.
DESIGNING THE CHANNELS AND THE INNER CLEARANCES IN GEROTOR PUMPS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
P. Antoniak and J. Stryczek,
2006,
volume 1,
pp. 219-234,
Juni 2006
view abstract
The authors of the paper present research on the question of influence of the plate directional control valve design
parameters and of the operational parameters on the pressure characteristics inside the displacement chamber of the
gerotor pump. The research was carried out in two stages. At the first stage, as a result of the theoretical investigation,
the qualitative influence of the parameters in question on the pressure characteristics was specified. At the second
stage, with the use of an experimental gerotor pump, verifying research was carried out. In the final part of this article,
using the verified theoretical model, the optimum design of the inner channels for gerotor pumps is presented.
DESIGN METHODOLOGY FOR FLUID POWER SYSTEMS AND PRODUCTS SYNERGY, INTEGRATION AND BALANCE
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
T. O. Andersen and M. R. Hansen,
2006, August 2006
view abstract
The envisaged objective of this paper project is to extend the current state of the art regarding the design of complex
fluid power mechatronic systems utilizing an optimisation approach.
We propose to investigate a novel framework for mechatronic system design. The novelty and originality being the
use of optimisation techniques. The methods used to optimise/design within the classical disciplines will be identified
and extended to mechatronic system design.
DESIGN OF A HYDRAULIC SERVO SYSTEM FOR ROBOTIC MANIPULATION
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Choux and G. Hovland,
2008,
pp. 391-400,
Juli 2008
view abstract
In this document the design, control and simulation of a hydraulic model for grasping an object is presented. The
principal equations that constraint such a system are first investigated through the presentation of the hydraulic
components which constitute the model. Their intrinsic characteristics are discussed as well as their interactions with each other. The controller that best fit this application is found to be a hybrid position/force control where the external forces are considered as a disturbance. In the last part of this document the model is simulated with more realistic component parameters including Stribeck effect friction, leakage and nonlinear valve characteristics. The results found with this simplified model show good correlation with the more realistic simulated environment.
Design of a Hydraulic System for Liquid Packaging
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
S. Castagnetti and M. Milani and F. Franzoni and F. Grasselli,
2010,
volume 2,
pp. 709-716,
Juni 2010
view abstract
The paper analyzes the dynamic behavior of a hydraulic system devoted to the industrial automated packaging of
beverages. More in detail, a lumped and distributed numerical approach is used to build the model of the multiactuators
hydraulic system, produced by Tetra Pak® to fill up and close the Tetra-Brik®. In particular, both the jaw
actuators and the cutting cylinders, as well as the hydraulic power unit used to feed the actuation system, are included
in the numerical model. The model reliability and accuracy are addressed by comparing the time-history experimental
and numerical results of the main hydraulic and mechanical quantities for the actual production rate. Afterwards, the
system architecture is studied for production-rates different from the reference one, and the effects of the hydraulic
behavior variation on the efficiency are highlighted. Finally, some of the main design parameters (such as the pump
displacement, the pump-shaft speed, the accumulator volume or the pressure relief valve pressure gradient) are
changed and combined, in order to determine the circuit dimensions that maximize the system efficiency in the
production-rate range.
Design of a Hydrogen Production and Power Generation System Based on the Reaction of Aluminum with Water
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
S. Mercati and M. Milani and F. Franzoni and L. Montorsi,
2010,
volume 2,
pp. 765-774,
Juni 2010
view abstract
This paper shows the preliminary results obtained in the design of a new cogeneration system based on the combustion
of aluminum particles with water. The fluid power machine, which is aimed to produce continuously high temperature
steam and hydrogen, is based on a new concept which offers important advantages when compared to the traditional
hydrogen production systems, such as no pollutant and GHGs emissions produced during the system operation.
Moreover, the high temperature hydrogen steam mixture produced during the combustion can be converted into
mechanical work, or eventually used in a co-generation system by means of heat-exchanger.
A simplified model of the aluminum – water reaction is included into a lumped and a distributed parameters numerical
model of the combustion chamber, to estimate the performance of the ‘core’ of the co-generation system. The modeling
is carried out by using the multi phase and gas mixture combustion theoretical principles, to relate the thermo-fluid
dynamics characteristics of hydrogen and steam to the control system parameters: the water pressure, the water
temperature, the water mass flow, the aluminum temperature and the aluminum mass flow.
Therefore, the behavior of the combustion chamber is simulated, and the influence of main design and operating
parameters on flame temperature and phase concentration is stated.
Finally, the effects of the main fluid power operating parameters and the structural combustion chamber parameters on
the energy conversion efficiency and power output are investigated.
Design of a Lyapunov Controller for an Electro-hydraulic Actuator During Contact Tasks
Navid Niksefat and Christine Q. Wu and Nariman Sepehri,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 299-307,
Juni 2001
view abstract
In this paper, an algorithm is developed for contact task control of electro-hydraulic actuators. The goal is to design and experimentally evaluate a robust controller that allows a hydraulic actuator to follow a free space trajectory and then make and maintain contact with the environment for exerting a desired force. First, the dynamic model of a hydraulic actuator interacting with an environment is described. Then, a Lyapunov-based controller is designed, which regulates the actuator's position and upon contact with the environment switches to a force controller. Extended Lyapunov's second method is used for stability analysis of the developed control system, which consists of nonsmooth dynamics. The stability of the system is guaranteed by using a smooth Lyapunov function under the condition of existence and uniqueness of Filippov's solution. The efficacy of the proposed nonlinear controller is verified via experiments. The experiments are performed on an industrial hydraulic actuator equipped with a servovalve and include motion through free space, contact with the environment and the transition between the two.
Design of a New Pressure Regulator with Electronic Control: Friction Forces Analysis
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Belforte and D. Maflodo and L. Mazza and T. Raparelli,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 325-329,
April 2005
view abstract
The paper investigates the friction forces developed between the sliding members of a proportional pressure regulator with a power stage consisting of a poppet-type pressure reducer driven by a piston, and a pilot stage with two MATRIX high frequency digital monostable 2-way valves controlled by the PWM technique. Carried out using a specially developed test bench, the investigation identified lubricants and seal geometries that minimize friction forces. Effects of different greases and seal geometries were evaluated and different solutions were compared.
Design of a Nonlinear Adaptive Controller for an Electrohydraulic Actuator
K. Ziaei and N. Sepehri,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 449-456,
September 2001
view abstract
This paper presents a new implementation of indirect model reference adaptive (MRA) control scheme for positioning of hydraulic actuators that operate by low-cost proportional valves. A proper linear discrete-time plant model is used which has dead-time and no zeros, eliminating the possibility of unstable pole-zero cancellation. The robustness of the parameter adaptation is achieved by employing the recursive least-squares algorithm in combination with a dead-zone in the adaptive law. It is shown that while the controller is adequate for hydraulic valves with linear flow characteristics, it exhibits low performance in the presence of deadband and nonlinear orifice opening characteristics of low-cost proportional valves. The linear plant model is therefore augmented by adding a static nonlinearity. The resulting nonlinear MRA controller is shown to have improved performance over its linear counterpart. Step-by-step experiments are presented to confirm the effectiveness and performance improvement of the proposed method.
Design of an Undulate Foot Robot
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Ma and C. Yang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 163-166,
April 2005
view abstract
Currently, the most majority of robots using their standing legs or revolving mechanism like wheels and screw propeller to move and walk on land or in fluid environment. However, these normal robot locomotion forms may be very difficult to be applied in changeful terrain. Moreover, we have previously neglected the locomotion forms of mollusk like gastropod which may open out new forms of robot locomotion. In this paper, we bring out a new kind of moving form---the undulate form of robot locomotion and propose a new kind of robot ---Undulate Foot Robot(UFR) which moves by the travelling wave its foot generates and can move in viscous fluid environment.' In order to accomplish the two objectives, the mechanical design of the proposed UFR is implemented by a Parallel Array of kinetic unit mechanism(PAM) named Eccentric Cam (EC). The whole mechanism is called PAEC. Each EC mechanism can achieve a detailed sine wave and thus the whole
mechanism can accomplish a travelling wave which results in the UFR's movement in a viscous fluid environment. Furthermore, the kinetic parameters of the UFR can be adjusted in a proper range to fulfill the requirement of different applications.
Design of a Train Separator for Hydraulic Capsule Pipeline Control
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
H. Du and S. S. Nair,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 65-70,
November 1996
view abstract
Design of an important component for reliable functioning of hydraulic capsule pipelines [1-3] is discussed. A method for sizing the separator and predicting the spacing between capsules after the capsule train passes through the separator is developed. The proposed design has been implemented in hardware. Limited experimental results show that the capsules were separated as expected and the observed spacing between capsules matches the calculated values predicted by analytical methods.
Design of a vibration-isolated cushion to reduce the noise and vibration of a hydraulic breaker
B.-S. Kim and M.-G. Kim and S.-H. Lee and M. G. Lee,
In Proc. of the Institution of Mechanical Engineers Part I, Journal of Systems and Control Engineering,
2010,
volume 224,
pp. 1-9,
view abstract
The objective of this research is to develop a low-noise and low-vibration hydraulic breaker that is able to meet the proposed strict noise certification and environmental regulations on construction equipment. Noise and vibration characteristics of a conventional hydraulic breaker are examined using a noise test and acoustic analysis. A dynamic absorption mechanism is applied to the current upper cushion to lower the noise energy and vibration force transmitted by the operating mechanism. The high effectiveness of the developed hydraulic breaker system on the noise and vibration problem is verified using a noise test and acoustic analysis.
DESIGN OF CASCADE CONTROLLERS FOR A HYDRAULIC ACTUATOR
M. A. B. Cunha and R. Guenther and E. R. De Pieri et al.,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 35-46,
August 2002
view abstract
This paper addresses the design of the cascade controllers for the position trajectory tracking control in hydraulic
actuators. The cascade strategy consists in interpreting the hydraulic actuator mathematical model as two interconnected
subsystems: a mechanical subsystem driven by a hydraulic one. From this interpretation, cascade controllers
with suitable properties were proposed. In this paper, in order to state the design guidelines for the cascade controllers
gains, a theoretical analysis focusing on the relations between controllers gains and performance is presented. Implementation
aspects required to obtain an optimised performance are also discussed. Experimental results support the
design guidelines and the implementation aspects approached in this work.
Design of Electro-hydraulic Control System for Walking Beam Mill Furnace
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Chengyu and Z. Jingyi and C. Dongning,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 713-716,
April 2005
view abstract
Walking beam mill furnace, a type of advanced furnace used in rolling plant of metallurgical industry, has the advantage of powerful heating capacity, good heating quality, short heating cycle and good longevity. However, the design of electro-hydraulic control system is comparatively perplexing. The bed of walking beam mill furnace consists of fixed beam and walking beam driven by cylinders. There are critical movement requirements for walking beam such as acceleration and deceleration control, corresponding measures to decrease mechanical shock, which bring high demands for the electro- hydraulic control system.
The functions of walking beam mill furnace controlled by PLC (Programmable Logical Controller) are presented in the article. Reliability design of PLC control system and principle of the control procedure are introduced. Cartridge valves are adopted in the hydraulic system for the furnace. Modular design of PLC control system, multipoint operation, such as local and remote operation, and multiple operator schema, namely, the system can operate in either manual or autonomous mode, good anti-jamming capability and favourable configuration are main features of the PLC control system. It is convenient to installation and connection of components owing to modular structure. Touch screen, a friendly MMI (Man Machine Interface), including operation panel and condition monitoring, can lighten labor intensity to a considerable degree.
Design of Fluid Chambers in Control Unit of Variable-displacement Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
X. Kong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 594-596,
April 2005
view abstract
The fluid chambers and orifices in the control unit of variable-displacement pump will make great influences on the control performance of variable-displacement pump. Some works (Huang et al., 1988; Li et al, 2001; Wu et al, 1992) have been done on the optimum design of the orifices. However, the influences of fluid chambers were neglected in these research efforts. It is well know that the volume of fluid chambers should be as small as possible so that its influences could be neglected. In order to quantify the condition, the mathematic model of the load sensing control unit of variable-displacement pump is established and represented as a form of system block diagram. Based on it, the design problems of the fluid chambers and damping orifices are discussed. A few of simple and practical design formulas are put forward, which are valuable to the design of load-sensing variable-displacement pump.
Design of Hydraulic Systems for Automotive Applications
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
M. Ernetti and M. Milani and D. Bottazzi and S. Simonini,
2010,
volume 2,
pp. 717-726,
Juni 2010
view abstract
The paper deals with the analysis and the design of “secondary” hydraulic systems for high performance cars. In
particular, the lumped and distributed parameters approach is combined with the 3D CFD analysis to describe the
behavior of hydraulic systems of the power transmission unit and the gear selection of a Ferrari California. First, the
steps followed to model both mechanical actuators and hydraulic components are highlighted. Then, the hydraulic
subsystems are operated with reference duty-cycles, and the on/off and proportional valves are controlled in order to
obtain a power metering that reproduces the actual sub-system dynamic behavior. Finally, the modelling reliability and
accuracy are addressed by comparing numerical and experimental data, and the dependency of the power supply unit
operating characteristics on reference duty-cycles is evidenced.
Design of integrated pressure,-flow and temperature sensor for hydraulic systems
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
C. W. Groepper and P. Y. Li and T. Cui and K. A. Stelson,
2006,
pp. 321-334,
September 2006
view abstract
The pressure difference between the inner and outer radii of an elbow is evaluated for suitability for flow measurement in fluid power systems. This pressure difference will be measured with a MEMS sensor, which also can measure the system pressure and temperature. Design tools used in the analysis include computational fluid dynamics (CFD) simulation and experimental measurement. Two alternative calibration methods are presented. When the first method is used for calibration, the elbow flow meter exhibits a linearity of 1.7%, an average accuracy of 1.5%, and a repeatability of 1.1% over a turndown range of 12:1. Slightly less accuracy and less sensitivity to viscosity variation was noted when the second calibration method was used.
Design of Modern Hydraulic Tank Using Fluid Flow Simulation
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
V. Tič and D. Lovrec,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 469-482,
März 2010
view abstract
The aim of the paper is to present the issue of hydraulic tank design. Hydraulic tanks are an often neglected part of the hydraulic system, although they perform many important roles besides storing hydraulic fluid.
The main focus of the presented work is on the proper design of commonly-used square hydraulic tanks. The theoretical background is presented at the beginning of the work. Both, steady-state and transient simulations of fluid-flow were performed using the Ansys Workbench, in regard to the theoretical knowledge. The base model was an industrial 400 litre hydraulic tank. The obtained results were then used for designing a new tank and a full scale hydraulic power unit was
built.
Design of Objective Functions for Optimization of Multi-Domain Systems
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
J. Andersson and P. Krus and J. Pohl,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 41-47,
November 1998
view abstract
Engineering problems are often characterized by many conflicting objectives which span over several engineering domains. In this paper an approach to design of objective functions for engineering problems is presented.
Multi-domain systems can be characterized as
complex systems which combine different fields of
engineering. Here an aircraft landing gear is studied
which is a true example of a multi-domain simulation
problem due to the presence of mechanical, electrical
and hydraulic sub systems. On this simulation model a
non-gradient optimization strategy is applied where the
formulation of the objective function is supported by the
House of Quality method. The design of an objective
function for optimization is in many cases a complex
procedure involving a great amount of expertise. The
House of Quality method is used here both to facilitate
team activities and to elucidate the relation between
system characteristics and system parameters.
Design of Proportional Anti-Saturative Load-Sensing Control Blocks
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
M. Scolari and M. Milani and D. Bottazzi and G. Cagni,
2010,
volume 2,
pp. 783-793,
Juni 2010
view abstract
The paper highlights the main steps followed to develop a new generation of proportional control blocks for flowsharing
load-sensing applications. More in detail, the multi-dimensional CAE design is extensively used to design and
improve the performance of both proportional control valve sections, and different configuration of anti-saturative
pressure compensators. In particular, the lumped and distributed parameter modeling has been applied in order to
determine the influence of notch shape, number and geometrical characteristics on metering properties.
The numerical models of the different parts are grouped in a customized library. Moreover these models are properly
combined in order to obtain a second library containing the different elements needed to build a complete proportional
load sensing control block.
Finally, the control blocks more suitable for load-sensing anti-saturative applications (i. e. telehandler) are selected.
Both steady and dynamic conditions are considered during the analysis.
Design of Single Stage Pressure Relief Valve Using Time Domain Simulation and CFD Analysis
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. O. Andersen and M. R. Hansen and H. L. Sørensen and F. Conrad,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 472-476,
April 2005
view abstract
In this paper an approach to the dimensioning of a single stage pressure relief valve is presented. The valve in question is a pressure relief valve that is designed based on a set of typical design criteria: crack pressure, maximum flow, maximum slope of pressure flow characteristic, available space and dynamically stable. The design variables include the dimensions of the spool the shaping of the rim at and the valve spring. The performance criteria as used to formulate a set of allowable intervals for the design variables. This formulation is carried out based on a mathematical analysis of the valve including time domain simulation and CFD analysis. The latter was necessary in order to link the geometrical design variables with the flow force and flow discharge characteristics. A prototype was designed from the computed data and experimental testing verifies that the design performance, including stability, was reached.
Design of the Pneumatic Servo-actuators of a 3 d.o.f. Motion Simulator
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
S. Pastorelli and M. Sorli,
2004,
pp. 433-440,
Juni 2004
view abstract
This paper presents the development of the pneumatic servo-system used to drive a 3 d.o.f. motion
simulator for single-user virtual reality applications. In particular the static and dynamic performances of
the matching of the elements regulating the fluid power and the element transforming the fluid power in
mechanical power are analysed. A linear model is assumed and the main parameters of the transfer
functions between input reference, output position and force disturbance are discussed. The methodology
presented has general effectiveness and it may be extended in designing similar actuation systems.
Design optimization of a special relief valve with response surface methodology
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
P. Casoli and A. Vacca,
2007,
pp. 413-429,
September 2007
view abstract
This paper describes the utilize of a numerical procedure for the analysis and the optimization of an hydraulic component, namely a particular direct acting relief and anticavitation cartridge valve. The element taken as reference is usually connected to a hydraulic line with the aim of keeping the circuit pressure between two different set values; moreover it can work as anti-shock valve, avoiding pressure peaks.
The developed procedure is based on Response Surface Methodology techniques, adopting the path search method known as Steepest Descent. For this purpose, the valve behaviour is analytically described by means of a properly defined objective function. The procedure approximates this objective function with a simple model whose coefficients are evaluated using the predictions performed by a AMESim® model of the valve, developed in C++ language by the authors. The sets of simulations for the fitting model are planned according to Design Of Experiments techniques. The entire optimization algorithm has been developed with MATLAB® scripts, which are able to plan the simulation with the AMESim® model of the valve, automatically execute the simulations, post process the results and finally establish the optimal configuration of the component taken as reference.
The considered starting point for the optimization process is given by a stock configurations of the valve, considered also for the experimental validation of the AMESIM® model in previous works. Three different optimal configurations of the valve, for different values of the preset pressure, have been proposed, and prototypes of the new designs have been realized. Experimental investigations point out the improved performance of the proposed designs, highlighting the potentials of the developed optimization methodology.
Design Optimization of Harvester Head and Actuation System of Forest Harvester
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. O. Andersen and M. R. Hansen and O. O. Mountsen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 297-301,
April 2005
view abstract
This paper is on the analysis and subsequent efficiency optimization of a forest harvester. As basis for the optimization the existing machine has undergone substantial experimental testing with a view to determine the loading that the harvester head is subjected to and also the corresponding efficiency of the hydraulic actuation system during a typical working cycle.
Based on the results a redesign is put forward both of the mechanical design of the harvester head yielding a weight reduction of about 10% but also of the hydraulic actuation system where the use of an extra low cost pump yields an increase in efficiency from 0.4 to 0.5 for the crane and from 0.45 to 0.5 for the harvester head.
Design Optimization of the Sliding Elements of External Gear Machines
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
A. Vassena and A. Vacca,
2010,
volume 2,
pp. 561-577,
Juni 2010
view abstract
This paper describes a numerical methodology for the design optimization of sliding bearing blocks of external gear
pumps. In these machines, the sliding elements facing the gears need to be carefully designed in order to achieve high
performance and reliability. This work describes how the design of the mentioned elements can be obtained as a
solution of a particular multi-objective optimization problem, defined by proper objective functions, variable inputs and
constraints.
For the evaluation of the objective functions the simulation tool HYGESim (HYdraulic GEar machines Simulator) has
been utilized. This tool, working in co-simulation with a proper CAD-3D geometrical model, is able to calculate the
main fluid dynamic features related to the operation of external gear pumps or motors. These tools are used within a
proper optimization flow-chart developed in the modeFrontier® optimization environment. By using proper optimization
strategies, like Genetic Algorithms and Response Surface Methodology, it has been possible to define and iterates the
values of the input variables in order to reach the optimal configuration.
The validity of the optimization methodology is confirmed experimentally by the high volumetric efficiency and the
reduced pressure ripple pulsations of the prototypes realized on the basis of the results achieved using the presented
optimization procedure, respect to the standard, not-optimized design of bearing blocks.
Design Principles for Proportional Pressure Reducing Valves in Mobile Applications
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
D. Linden,
2007,
volume 2,
pp. 147-159,
Mai 2007
view abstract
Proportional pressure reducing valves are an important element in modern hydraulics. The applications and their requirements are many and diverse.
Not surprisingly, today there are many different design principles available on the market which frequently leave the user helpless in view of this huge diversity.
The paper introduces the different design principles, analyses them systematically in detail and points out their advantages and drawbacks with respect to the application demands. For some widespread applications typical requirement profiles are elaborated. Application requirements as well as
the typical performance of a design are graphically represented. By systematically matching these graphs, it is possible to select the optimum valve
design for a given application.
Design, virtual prototyping and test of a regenerative shock absorber for race cars
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Mare, Jean-Charles and Berthe, Paul-Etienne,
2010,
pp. 447-460,
September 2010
view abstract
This communication deals with energy regenerative damping. A two quadrants electrohydrostatic damper is designed, simulated, manufactured and tested. The proposed damper
involves a single rod linear jack, a charging accumulator, a manifold block with four check valves mounted as a full hydraulic rectifier and a hydraulic motor connected to an electrical generator. The proposed top level modelling is performed in order to point out in a simple and efficient way the contribution of both functional and parasitic effects such as inertia, friction, valves cracking pressure and flow rate pressure gradient. On basis these results, the initial design is modified to reduce the motor flow and to admit more conventional components for the demonstrator. A design exploration is run for the components sizing with special consideration to off-the-shelf references. Then, a virtual prototype is built within the LMS-AMESim simulation environment to verify the preliminary design and to assess the damper transient behaviour. Finally, the experimental results measured from the individual test of the first prototype are displayed and analyzed.
Detecting and influence of cylinder mounting backlash in a hydraulic position servo
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
E. Mäkinen and T. Virvalo,
2006,
pp. 305-317,
September 2006
view abstract
Studies with a pneumatic position servo have shown that it is difficult to detect mounting backlash by only monitoring the position error. Is the situation different or the same in hydraulics? In this paper, the detection and influence of cylinder mounting backlash in a hydraulic position servo is studied. A high performance position control system is realized by using a State Controller. The methods to detect the backlash and the influence of the backlash on the system performance are presented. The influence and the detection of the backlash are discussed and the results are enlarged based on the simulations.
Detection of Cylinder and Valve Leakage in Hydraulic Position Servo
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
E. Mäkinen and T. Virvalo,
2007,
pp. 53-66,
September 2007
view abstract
Leakage in a cylinder or in a valve increases damping and position error of hydraulic position servo systems, especially under external load. During the operation of servo systems some wear might occur both in servo valves and cylinders causing increasing leakages in control notches of servo valves or in seals of cylinders. Experimental and simulated results show that individual leakage paths can be detected based on their influence on the position error without any extra sensors. If more than one of leakage paths takes places simultaneously, only some of them can be separated. Leakage has only slight influence on the other performance of the system than the steady state position error.
Detect of piston seal leakage in pneumatic position servo cylinder drive
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
T. Virvalo and E. Mäkinen,
2006,
pp. 186-194,
Mai 2006
view abstract
Condition Control and Monitoring have strongly increasing role also in fluid
power field. Detecting different malfunctions is the main task in both Condition Control and
Monitoring. In principle, a malfunction can exist in any part of a pneumatic servo system; i.e.
cylinder and load, servo valve, position sensor, controller, and power supply. Problems are
how to detect a right kind of malfunction and what to do after that. Some malfunctions are not
so critical but their influence increases little by little and deteriorates the performance of the
system little by little like a leakage.
In this study the influences of increased leakages in the valve control notches as well as in the
piston seal on the performance of the position servo system are studied. The positioning of an
inertia load under a reasonable gravitational force is realized with a pneumatic control
system. The individual influence of different leakages on the performance is firstly studied by
simulation. Then attempts are made to detect the individual leakages when their combination
varies randomly. Experimental test are also carried out with animated leakages.
According this study, both leakages, in a cylinder or in a valve, influence in the same kind the
performance of position servo systems. They increase damping and position error. In the
initial tuning the leakage of the servo valve can most often be compensated by suitable tuning
of valve zero point. Servo valve leakage causes always at least low frequency hunting in
position servo applications, but it may be hard to detect, before it is remarkably high. The
best ways to detect piston seal leakage are increased steady state position error while there is
a good dynamic behavior without hunting incipient.
Determination of flow forces in hydraulic valves
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
M. Domagala and E. Lisowski,
2004,
pp. 115-122,
Juni 2004
view abstract
This paper deal with computer methods employed in modeling hydraulic components. Among many
available methods, the most suitable to modeling complex objects such as hydraulic systems and
components seems to be numerical methods, particularly CFD methods. This paper presents the way of
using these methods together with optimization in order to improve relief valve characteristics. As known
flow forces have significant influence on valve characteristics. Besides, authors researches show that
geometry of valve components influence on flow forces. Therefore an attempt of looking for geometry of
valve components to improve its characteristics has been undertaken. By mathematical description of
valve geometry and CFD analysis we may find relation between flow forces and valve geometry. Such
description is presented in this paper. Also optimization problem has been defined and presented. After
solving this task we may find geometry of the valve which allows to improve vlave characteristics.
Determination of Flow Rate Characteristics of Pneumatic Solenoid Valves Using an Isothermal Chamber
K. Kawashima and Y. Ishii and T. Funaki and T. Kagawa,
In Journal of Fluids Engineering,
2004,
volume 126,
pp. 273-279,
März 2004
view abstract
In this paper, two new methods for obtaining the sonic conductance and the critical pressure ratio of pneumatic valves are proposed. Both methods use a chamber that can approximate isothermal conditions. This was achieved by filling the chamber with metal wire, which creates a larger heat transfer area and heat transfer coefficient. The sonic conductance and the critical pressure ratio are obtained by measuring the pressure in the chamber during charging and discharging. These methods take only seconds to perform and require less energy than the ISO 6358 procedure. The major factor in the error for the pressure response during the charging of the isothermal chamber is the upstream pressure change. Nevertheless, the sonic conductance can be determined within a 3% uncertainty. In addition, the sonic conductance calculated from the pressure response during the discharging of the chamber can be determined within a 1,2% uncertainty.
DETERMINATION OF K COEFFICIENTS FOR IRREGULAR FLOW PASSAGES IN HYDRAULIC MANIFOLDS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
A. Borja and S. Weber,
2006,
volume 2,
pp. 609-621,
Juni 2006
view abstract
Pressure drop and flow measurements were made on the internal flow passages of a hydraulic manifold manufactured
using drills to create complex connections. The data obtained was used to calculate the loss or K coefficient. Complex
connections for the purpose of this paper include non-standard angles between drillings and connections made when
centerlines of the drills are not perpendicular. Measurements were taken from the laminar to the turbulent flow regime and
the experimental set-up was optimized to concentrate measurements on the immediate area between flow passage
connections. Collected data such as differential pressure and volumetric flow rate are used to calculate the K coefficient for
each of the passages tested.
The purpose of this study is to improve the knowledge base on calculating pressure drop. This will enable manifolds to be
optimized in the design stage to minimize pressure drops to improve overall system efficiency. In order to validate the
experimental procedure, tests were conducted on 45° and 90° elbow fittings with inside diameters of 9.5mm (0.375 inch),
12.7mm (0.500 inch) and 19.1mm (0.750 inch), the results were compared with tabulated coefficients for consistency. The
study has revealed that the experimental process is consistent with other experiments performed to achieve the same
coefficients found in literature. Analysis of the experimental results have led to the development of a few simple design
guidelines to minimize pressure drop in hydraulic manifolds.
Determination of Optimal Lifetime for Hydraulically Equipped Sappers Machines (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
M. Musil,
2006,
pp. 101-105,
Mai 2006
view abstract
systems. The main criterion is economic life of machinery. In Czech army there are KN-251,
UDS 110a etc.
Topical problems of logistic in Czech army are big costs during their service life. Total costs
are multiply then purchase costs. Knowledge in technical conditions is necessary for
economically and functionally useful maintenance system. Army technics is divided into two
categories – operational technics and stored technics. Especially deterioration of sealing
rubbers and corrosion in hydraulics of saved technics are big problems.
The major goal is analyse of costs of the identical machinery during their service life and
classification of optimal duration of usage in Czech army.
Determination of Relief Valve Characteristics by the Use of CAD System and CFD Tools
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
E. Lisowski and M. Domagala,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 211-220,
November 2003
view abstract
This paper presents the way of determination of direct relief valve characteristics by the use of
CAD system (SolidWorks) and CFD tool (Fluent). Two relief valves, which slightly differ,
were analyzed to see what influence has geometry of valve components on its characteristics.
Conducted CFD analysis was aimed at receiving flow forces which appears at valve
components during fluid flow. Obtained values were next used in mathematical model to
determine valves characteristics. It showed that even small changes in valve geometry have
influence on valve characteristics. Theoretical research were also verified on the built tests
stand.
Determination of the Operational Point for the Pneumatic System Sizing
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
M. D. Hené and Y. E. A. Mendoza and L. G. de Oliveira and V. J. De Negri,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 343-354,
März 2010
view abstract
This paper presents a theoretical-experimental study aiming to determine operational points of pneumatic systems according to the choice of the directional valve or proportional directional-valve and the pneumatic actuator. This study is valid for on-off systems or closed loop positioning systems. In the last case there is a period of time where the speed is approximately constant so that the operational condition of interest can be observed. The proposed mathematical model establishes intersection points between curves associated to the valve and cylinder models determining an operational condition where the speed is constant. The mathematical model is validated by experimental data obtained on a test bench. The results presented show to be promising for the developing of a new conception and sizing methodology for pneumatic systems.
Determining the probability of performance and stability for a metering poppet valve
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
R. Carpenter and R. Fales,
2010,
pp. 505-522,
September 2010
view abstract
A method is developed for determining the probability of achieving stability and achieving a performance objective of a metering poppet valve. The Work is an application of a probability stability/performance analysis technique being developed by the authors. Using statistical information such as the probability density function of the system parameters, the goal is to determine the probability of a metering poppet valve system achieving or not achieving a frequency domain performance specification. An H-infinity control system is applied to the valve. A performance specification is given for the valve and converted into a performance Weight transfer function for the analysis. The metering poppet valve is an example of realistic higher order system With uncertain parameters. The valve has spring feedback integrated into a pilot control system. The spring rate, valve component masses, and viscous friction are considered to be random variables with normal distributions. In this Work, a prediction is made of the percentage of valve systems that would not achieve the given frequency domain performance requirement. The prediction applies if the valve were manufactured in a series production With component parameters that have known statistical qualities.
Deterministic Surface Texturing for the Tribologic Contacts in Hydrostatic Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
L. Leonhard, H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 49-59,
März 2010
view abstract
In times of decreasing energy resources and increasing energy costs the demand for highly energyefficient propulsion technologies increases as well. Hydrostatic drives are known for their poor efficiency compared to mechanical solutions. Nevertheless, they are used in many technical applications because of their inherent advantages such as good dynamic behaviour, good and flexible controllability and an unsurpassed power to size ratio. To secure the wide-spread application of hydrostatic propulsion technology in the future, the impact of deterministic surface texturing on the energy efficiency of the tribologic contacts in hydrostatic machines is discussed. The paper introduces a simulation approach based on similitude theory to identify optimal texture geometry by means of CFD-Simulation.
Developement of Multi−Machine Remote Control Platform
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
J. Saarinen and M. Hyvönen and J. Suomela and J. Vilenius and A. Halme and K. Huhtala,
2007,
volume 2,
pp. 9-23,
Mai 2007
view abstract
The paper describes the components of a multi-machine teleoperation system. The main components of the system are: work site, work machines, teleoperation/control station
and a simulator. The components are joined together with a software architecture that enables the flexible implementation of distributed systems. The control of the system is done via the Internet. As a result the system presents a full featured test platform for multi work machine teleoperation with real work machines at a real work site.
The system acts as a development platform for the Finnish center of excellence in Generic Intelligent Machines research (GIM). The GIM goals are to study the multimachine
teleoperation and develop the future work site concept.
DEVELOPING AND TAILORING A CFD CODE FOR MULTIPHASE MULTICOMPONENTS FLOWS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
F. Franzoni and M. Milani L. Montorsi,
2008,
pp. 348-364,
Juli 2008
view abstract
This paper focuses on the development and the tailoring of a open source multidimensional CFD code to the analysis of
the internal flow-field in hydraulic components. A preliminary study of two basic geometries is carried out by
simulating the efflux of an incompressible fluid through circular pipes and through an abrupt section change
determined by a small sharp-edged cylindrical orifice. A qualitative description of the internal flow-field distribution, and a quantitative comparison of pressure and velocity profiles along the pipe axis are used to asses the
multidimensional open-source code capabilities. For the circular pipe the results are compared with experiments and
with theoretical trends coming from literature fundamentals (Hagen-Poiseuille theory and Nikuradse interpolation),
while for the abrupt section change experimental measurements available in literature are taken as a reference for the
numerical accuracy determination. Furthermore, the influence of grid resolution and of turbulence models on the vena
contracta on the characteristics recirculating regions, on the reattachment point and on the pressure and velocity fields
is addressed. Afterwards, to investigate the mixing of different fluids, a preliminary analysis of a reference test case is carried out. The modified VOF approach, used for modeling the fluid-fluid mixing process, is tailored in order to account for turbulence. Different grid resolutions and turbulence models are adopted and results are compared with
experiments in order to asses their influence on the interface and on the fluids distribution inside the reference
geometrical domain. In particular, two different turbulence models (k-ε – SST) are implemented in the original code to
address their effect on actual fluids mixing. Finally, the dynamic behavior of a low pressure fuel rail is investigated
and the fuels distribution history within the rail is determined for different operating conditions to assess both the fuel mixture at injectors’ inlet, and to highlight the differences among the cylinders in terms of injected fuel blend.
Developing Fluid Technical Mechatronic Systems with Increased Efficiency Using the Principles of Lean Innovation
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
G. Schuh and M. Lenders and J. Müller,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 391-404,
März 2010
view abstract
An integrated development environment for fluid technical mechatronic systems has a significant relevance due to the collaboration of different disciplines and the resulting complex system structures. Therefore, such an integrated development environment for fluid technical mechatronic systems using the principles of Lean Innovation was developed and implemented within the BMBF Project Fluidtronic.
Developing intelligent hydraulic excavator
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
O. Karhu and J. Vilenius and J. Uusisalo and K. Huhtala,
2006,
pp. 265-274,
September 2006
view abstract
In this work the objective is to make a hydraulic excavator attachment more comfortable, accurate, and safer to operate. A commercial hydraulic excavator with four cylinders and mechanically activated on/off-valves was chosen as a platform. The valves were replaced with electronically activated proportional mobile valves and a microcontroller unit was designed and built to control the valves. In this research the intelligent properties related to the control valve are added to the microcontroller unit of the excavator. Among these properties are dead zone compensation, spool offset adjustment, ramped control signals, diverse control curves, and safety features for fault situations.
DEVELOPMENT AND CONTROL OF ENERGY SAVING HYDRAULIC SERVO DRIVES
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
R. Rahmfeld,
2000,
pp. 167-180,
September 2000
view abstract
This paper introduces a new hydraulic circuit for a pump controlled actuator with differential cylinder which
allows the replacement of today's valve controlled actuators. The actuator uses a constant low pressure source
and pilot operated check valves to compensate the difference between the in- and outgoing flow of the cylinder
chambers. Two developed control concepts with a servo pump as final control element are presented, one concept
is based on LQG/LTR method. The pump controlled actuator allows an improved utilization of primary
energy due to the omitted valves especially when taking recovery of potential load and brake energy and use for
other drives into account. Proof of function and verification of low energy consumption was done at a test rig for
linear actuators. Several measurement results are shown and briefly discussed.
DEVELOPMENT AND CONTROL OF ENERGY SAVING HYDRAULIC SERVO DRIVES
1st FPNI PhD Symposium Hamburg 2000
ISBN: FPNI,
Robert Rahmfeld,
2000,
volume 1,
pp. 167-180,
view abstract
This paper introduces a new hydraulic circuit for a pump controlled actuator with differential cylinder which
allows the replacement of today's valve controlled actuators. The actuator uses a constant low pressure source
and pilot operated check valves to compensate the difference between the in- and outgoing flow of the cylinder
chambers. Two developed control concepts with a servo pump as final control element are presented, one concept
is based on LQG/LTR method. The pump controlled actuator allows an improved utilization of primary
energy due to the omitted valves especially when taking recovery of potential load and brake energy and use for
other drives into account. Proof of function and verification of low energy consumption was done at a test rig for
linear actuators. Several measurement results are shown and briefly discussed.
Development and Implementation of an Advanced Power Management Algorithm for Electronic Load Sensing on a Telehandler
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Hansen, Rico H. and Andersen, Torben O. and Pedersen, Henrik C. ,
2010,
pp. 537-550,
September 2010
view abstract
The relevance of electronic control of mobile hydraulic systems is increasing as hydraulic components are implemented with more electrical sensors and actuators. This paper presents how the traditional Hydro-mechanical Load Sensing (HLS) control of a specific mobile hydraulic application, a telehandler, can be replaced with electronic control, i.e. Electronic Load Sensing (ELS). The motivation is the potential of improved dynamic performance and power utilization, along with reducing the mechanical complexity by moving traditional hydro-mechanical implemented features such as pressure control, flow-sharing, prioritization of steering, anti-stall and high pressure protection into electronics. In order to implement these features, the paper presents and tests a general power management algorithm for a telehandler. The algorithm is capable of implementing the above features, while also handling the dynamics of the system, taking into account saturation phenomena as flow limitation and cylinder endstops. The development of control for a variable-displacement axial piston pump using a three-way servo valve is also treated.
Development and Investigation of High-Speed Pneumatic Jet Valves by Lumped Parameter Modeling
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Z. Xiang and H. Liu and G. Tao,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 261-272,
März 2010
view abstract
Pneumatic jet valves were developed and manufactured for high-speed optical food sorting machine. A three-dimensional lumped parameter model (3D-LPM) is developed to evaluate the dynamic behavior of the developed high speed pneumatic ejector valve. The model accounts for the effects of flux fringing,
leakage, and material saturation through a nonlinear reluctance-element network. The model presented here is primarily aimed for use in design optimization. Results from the model are validated experimentally.
Development and Laboratory Tests of a Cheap, Robust, and Fast Check Valve for Industrial Applications
Proc. Ninth Scandinavian International Conference on Fluid Power, SICFP'05, Linköping, Sweden
A. Plöckinger and R. Scheidl,
2005, Juni 2005
view abstract
Although there is a need for cheap and very fast check valves in industry such components are not available on the market. Fast check valves designed for aeronautical applications have a very high price. Such fast valves would be utmost valuable components in many hydraulic systems where fast switching processes are going on. Quite often, some of the switching valve functions much easier could be replaced by check valves which basically should be much cheaper than active switching valves and, furthermore, need no external control. One very prominent example which highlights the enormous impact of such fast check valves is hydraulic variable valve train technology for combustion engines. Some patents [1,2] for instance rely on very fast check valves and experts in this field lament the missing of such. Having such cheap valves at ones disposal could turn systems with a considerable energy loss quite easily in one with lower energy consumption. Also shock absorbers at the stroke end of linear actuators performing very fast motion need fast check valves.
Development and Simulation of Lubrication Test System for Port Plate/Cylinder Block in Axial Piston Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
A. Qinglin and Z. Hua and Y. Huayong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 589-593,
April 2005
view abstract
The composition and schematic of the lubrication test system for port plate/cylinder block friction pair in axial piston pump is described. The subsystem and functions of the test system are introduced. The lubrication characteristics of port plate/cylinder block such as film thickness, bearing support capability and leakage can be measured. And the influence of working pressure, temperature, rotating speed and structure on the lubrication can be tested as well. The measurement. error is guaranteed to be less than 1μm by the high-accuracy electric eddy displacement sensors. The thickness of micron dimension lubricating film is feedback controlled with PID algorithm. The precise displacement feedback control system is simulated in dynamic with SIMULINK tool of MATLAB software, and it is significant to select the value of v0/βe Kce and PID for the design of precise displacement feedback control system.
Development Environment for Fluid-Power-Mechatronic Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
F. Engler and H. Baum and R. von Dombrowski,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 655-668,
März 2010
view abstract
Fluid-power-mechatronic systems are characterized by close networking among all the participating technical disciplines and through complex interactions between the subsystems required to attain the overall functionality. In view of this close interconnectedness of the development disciplines and the variety of companies involved as well as the resulting complex process structures, the development process for fluid-power-mechatronic systems is becoming increasingly difficult and the elimination of inadequacies in the product reliability is often realized using iterative problem solutions at a much later moment in the development process. Within the "Fluidtronic" joint project, which is funded by the German Federal Ministry of Education and Research, work is therefore being carried out by a consortium consisting of nine industrial companies and two research institutes on the creation of an adapted development environment in the form of a PLM (product lifecycle management) solution. The handling of data and information as well as the integration of simulation tools within this PLM concept form the core of this article.
DEVELOPMENT OF ACCURATE AND PRACTICAL SIMULATION TECHNIQUE BASED ON THE MODAL APPROXIMATIONS FOR FLUID TRANSIENTS IN COMPOUND FLUID-LINE SYSTEMS
E. Kojima and M. Shinada and J. Yu,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 5-15,
August 2002
view abstract
New simulation technique called the “system modal approximation” method for fluid transients in compound
fluid-line systems is developed and presented. Unlike existing approaches based on the modal approximation of the
input/output causality relationship of individual line element, this new method is based on the modal approximation of the
frequency transfer function itself of the output (wanted variable) to the input (source) considering the dynamic characteristics of total system. This simulation technique also has the feature that only the numerical data of the frequency
response of transfer matrix parameters of individual line element, which may be obtained from either theoretical model or
experimental measurements, is needed and that the wanted output variable alone can be calculated selectively in the time
domain by a simple algebraic expression in the form of recurrence formula. For complex fluid-line systems, the advantages of this technique over other existing modal approximation-based methods in accuracy, applicability, flexibility, computation time, etc. are discussed with experimental comparisons.
DEVELOPMENT OF ACCURATE AND PRACTICAL SIMULATION TECHNIQUE BASED ON THE MODAL APPROXIMATIONS FOR FLUID TRANSIENTS IN COMPOUND FLUID-LINE SYSTEMS (2ND REPORT: ENHANCEMENT OF ANALYTICAL FUNCTIONS FOR GENERALIZATION)
E. Kojima and M. Shinada,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 35-45,
November 2003
view abstract
In the previous paper, the authors proposed a new simulation technique called the "system modal approximation"
method (SMA method) for fluid transients in compound fluid-line systems. This technique was able to predict the behaviour
fast and accurately, and its superiority to other existing methods was verified by simulation and experimental
analysis. However, detailed considerations were limited to the cases whose transfer functions of output/input could be
approximated by the second order modes alone. This paper enhances the analytical functions of the SMA method so as
to be widely applicable to compound fluid-line systems with various kinds of system compositions and boundary conditions.
Specifically, the calculation methods of time response of the required output variable at any points are newly proposed
for case (A) whose transfer functions of output/input have to be approximated by the first order modes and derivative
element besides second order modes, and (B) whose boundary conditions are given by the relation between
pressure and flow-rate. Fluid transients in three kinds of compound fluid-line systems under the several different
boundary conditions including the occurrence of column separation are considered. Simulation results based on the
methods mentioned above are compared with both the solutions from the method of characteristics and experimental
results, and then the usefulness of the generalized SMA method is verified.
DEVELOPMENT OF A COMPACT AND TUNEABLE VIBRATION COMPENSATOR FOR HYDRAULIC SYSTEMS
J. Mikota and H. Reiter,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 17-30,
April 2003
view abstract
This publication is about vibration compensators for the attenuation of fluid flow pulsations in hydraulic systems.
After a problem definition and an overview of conventional devices, a compact and adjustable mass-spring resonator
featuring a hydraulic spring will be presented. The main advantages of this design are: simple and compact design,
excellent noise attenuation characteristics, suitability for all pressure levels through mean pressure compensation and
the possibility to alter the resonance frequency of the device in both a semi-active and active manner.
Besides the description of the working principle, the discussion of some phenomena occurring at high frequencies,
the treatment of some design aspects, such as the optimisation of the sealing gap geometry, dimensioning etc. and a
section devoted to compactness of vibration compensators, experimental results will be presented which prove the usefulness of the concept.
DEVELOPMENT OF A CONTROL CONCEPT FOR A HYDROSTATIC DRIVE WITH OPTIMIZED PRIMARY POWER CONSUMPTION
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
J.-C. Ossyra,
2002, Juli 2002
view abstract
This paper will discuss a new approach of reducing the fuel consumption of the combustion engine without limiting
the vehicles driving power. Therefore a new control concept based on a closed loop control of the hydrostatic drive and
the consideration of the losses within the hydrostatic transmission will be proposed. Since this approach uses very precise
loss models of the displacement machines applied in the hydrostatic transmission the model of plant will be presented
in detail. For a closed loop control for the angular velocity of the hydrostatic motor a nonlinear PID-control was
developed and tested in simulation by an acceleration maneuver. For experimental investigation a hardware-in-the-loop
test rig was designed using a variable displacement machine as a load simulator for the hydrostatic transmission. To
prove the sufficiency of the developed PID-control the command response will be investigated in simulation and experiment
for an acceleration maneuver.
Development of a direct pressure-sensing pressure-reducing valve for water hydraulics
K. Suzuki and E. Urata,
In Journal of Systems and Control Engineering: Proceedings of the Institution of Mechanical Engineers,
2008,
volume 222,
pp. 787-797,
Dezember 2008
view abstract
This paper submits a new design for a pilot-operated pressure-reducing valve for water hydraulics. The developed valve operates with a primary pressure of up to 14 MPa, secondary pressure range of down to 3.5 MPa, and a flow range of 2.7 to 15 l/min. The major features of the designed valve are: the main valve has two serial throttles to prevent cavitation, the pilot valve detects the secondary pressure directly, seepage from inlet port to pilot chamber is removed, and a viscous damper stabilizes the motion of the valve. A valve was produced whose dimensions were determined according to dynamic and static analyses. Experimental studies were carried out on the produced valve. No cavitation noise was observed for primary pressure up to 14 MPa. The steady state characteristics of the produced valve agreed well with the prediction by simulation. The measured secondary pressure variation was about 0.2 MPa at the maximum for the primary pressure of up to 14 MPa, and about 0.5 MPa for the flowrate up to 15 l/min.
Development of a Fast Low-Cost Switching Valve for Big Flow Rates
Proceedings of the 3rd FPNI-PhD Symposium on Fluid Power, Terrassa, Spain
B. Winkler,
2004,
pp. 599-606,
Juli 2004
view abstract
Advancements of hydraulic systems are necessary to keep them competitive with other drive systems. Two major topics for further improvements in hydraulics are energy efficiency and cost reduction. High accuracy and fast systems, for instance for fast and precise positioning tasks, mostly can only be realized by the use of servo valves. Such valves are costly and, moreover, their working is based on the resistance principle, which causes considerable losses. A promising method to achieve the mentioned goals is the use of fast, high flow rate and low-cost switching valves. Former investigations showed that switching valves with flow rates of about 100 l/min at 5 bar, switching times of 1ms and a price of about 100 in fullproduction run can meet these requirements. Commercial switching valves do not fulfill such demands. We developed a switching valve which fulfills the mentioned requirements on switching time, flow rate, and which has the potential to achieve a low price in full-production run. The valve spool is driven by a solenoid via a special transmission. The high flow rate was realized by a simple arrangement of several metering edges. In the course of its development we solved problems of unstable centered spool position. Its quite simple configuration is the main ingredient for a low prize in full-production run.
Development of a Fast Operating Clutch for Linear Movements
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
H.-J. Dennig and H. Binz,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 429-440,
März 2010
view abstract
Clutches for linear movements activating within milliseconds and having a high axial rigidity are not represented on the market so far. The Institute for Engineering Design and Industrial Design developed a clutch for linear movements focusing on these requirements by using the example of an overload system for spindle nut drives in machine tools. The clutch is hydraulically ventilated by a fast activating piezoactuator.
Development of a Fast Seat Type Switching Valve for Big Flow Rates
The Tenth Scandinavian International Conference on Fluid Power
B. Winkler,
In the Proceedings of the SICFP07,
ed. ,
2007, Mai 2007
view abstract
Highly accurate and fast response drives, for instance for fast and precise positioning, currently rely on big servo or proportional valves. Such valves are costly and are applied to resistance control with its inevitable energetic losses. A promising method to get rid of such losses and to reduce the valve costs is to use appropriate switching valves in combination with switching control. Former investigations showed that switching valves with flow rates of about 100 l/min at 5 bar and switching times of 1 to 2 ms can cover a reasonable range of applications. Commercial switching valves don’t meet such requirements. In this paper, a novel, hydraulically piloted, seat type switching valve which approximately fulfils the mentioned requirements on switching time and flow rate is presented. The high flow rate is accomplished by multiple metering edges in a plate type valve, just like the well known Hörbiger compressor valve. The fastest switching time which is strongly pressure dependent is about 1.5 ms. Its seat valve properties make it highly suitable for emergency applications and mobile hydraulic applications were absence of leakage is required.
Development of a Fault Simulator for Proportional Spool Valves
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
A. Bhojkar and R. Burton and G. Schoenau and D. Bitner,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 221-231,
November 2003
view abstract
Failure in a Single Stage Electro-Hydraulic Proportional Direction Control Valve (SS-EHPDCV) is
caused mainly by the spool sticking in the valve body. When the friction (stiction) gets large enough,
the solenoid is unable to generate enough force to move the spool making the valve inoperable. In
this research, a non-destructive fault simulator is developed which can introduce user defined friction
faults into the EHPDCV. By employing a closed loop position control scheme, one of the two
solenoids is used to generate a desired spool movement. The other solenoid is used to generate a
desired friction force. A closed loop control strategy, which uses feedback from a force transducer,
allows for the introduction of friction characteristics like stiction, coulomb and viscous friction.
This type of fault simulator can be used for testing and validation of a Condition Monitoring Scheme
(CMS), where typical friction characteristics in spool valves are used to predict the health of a valve.
(This paper is concerned with the first phase of experimental validation of a CMS, by developing a
fault simulator to artificially introduce the desired faults in the valve.)
DEVELOPMENT OF A HIGH-SPEED ON/OFF DIGITAL VALVE FOR HYDRAULIC CONTROL SYSTEMS USING A MULTILAYERED PZT ACTUATOR
H. Yamada and G. Wennmacher and T. Muto and Y. Suematsu,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 5-10,
Oktober 2000
view abstract
In this study, a high-speed on/off digital valve was developed for use in a hydraulic control system. The device basically
consists of a poppet valve acting as the main valve, and a multilayered piezoelectric (PZT) actuator for driving the
poppet valve. A hydraulic amplifier was adopted to increase the actuation of the PZT actuator to the poppet valve. A
compensation mechanism was set up to reduce this temperature effect in the hydraulic actuation of the PZT actuator.
This problem arises when the oil temperature increases and causes the valve displacement to fluctuate slightly.
The static and dynamic characteristics of the device were investigated by experiment and computer simulation. As a
result, it was found that the switching time of the valve is less than 0.7 ms. Moreover, the valve can be driven by a
PWM carrier wave using frequencies of up to 500 Hz. Additionally, the validity of the temperature compensation
mechanism was confirmed. Hence, this valve may be determined as feasible device to be used in hydraulic systems.
DEVELOPMENT OF A HYDRAULIC MASTER-SLAVE SYSTEM FOR TELEROBOTICS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
S. Kudomi and H. Yamada and T. Muto,
2000,
pp. 467-474,
September 2000
view abstract
In this study, we deal with a bilateral master-slave system for tele-robotics composed of electro-hydraulic servosystems.
In a teleoperated master-slave system, the master has to play two roles, firstly as a reference input
device to the slave and secondly as a haptic display device. The term “haptic display” indicates a function by
which the operator can feel a force fed back from the slave. In order to produce a haptic display composed of
hydraulic servo-systems, we must solve a problem called back-drivability, in which an actuator in a hydraulic
servo-system cannot be operated freely by manual means. As a practical solution to this problem, we propose a
driving method of actuator that uses a force sensor attached to the actuator. Furthermore, as an application of
the haptic display proposed, we construct a bilateral master-slave system composed of electro-hydraulic servosystems.
Experimental results of the manipulating motion of the system are given.
DEVELOPMENT OF A HYDRAULIC TELE-OPERATED CONSTRUCTION ROBOT USING VIRTUAL REALITY - NEW MASTER-SLAVE CONTROL METHOD AND AN EVALUATION OF A VISUAL FEEDBACK SYSTEM
H. Yamada and T. Muto,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 35-42,
Juli 2003
view abstract
In this study, we have developed a bilateral telerobotics system for a construction robot using virtual reality. The
system consists of a servo-controlled construction robot, two joysticks for operation of the robot from a remote place,
and a three degrees of freedom motion base. The operator of the robot sits on the motion base and controls the robot
bilaterally from a remote place. The role of the motion base is to realistically simulate the motion of the construction
robot. In this study, firstly, we propose a new method of master-slave control in order to make better feedback feeling
of the reaction force to the joystick for the tele-operated construction robot. Secondly, we tested the visual feedback
system for the construction robot using CCD video camera and computer graphics. For tele-operations, a video image
of the operation field is normally projected onto a screen to assist the operator. In this study, an additional computer
graphics (CG) was generated as a virtual robot to the real video image in order to present the end condition of the robot
arm. The usefulness of the system is confirmed by the experiments in this study.
Development of a Hydrostatic Transmission for Wind Turbines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
J. Schmitz and N. Vatheuer and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 477-488,
März 2010
view abstract
Within the scope of a current research project a hydrostatic transmission for wind turbines is being developed. In this paper the course of generating a first concept from known applications to be tested in simulation and on a test bench is described. Boundary conditions for the dimensioning are derived by analysis of the rotor forces and a morphological matrix is used to assemble concepts from various transmission modules. Finally, the chosen concept including the transmission controller and first simulation results are presented.
Development of a Miniature Air Compressor Driven with a Linear Electromagnetic Actuator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Jianhai and T. Noritsugu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 377-380,
April 2005
view abstract
This paper deals with a new type of miniature air compressor that it mainly consists of a linear electromagnetic actuator, electronic drive circuit, rubber cylinders intake and exhaust valves. The characteristics of the developed compressor are experimentally investigated. Only driven with the resonant frequency the compressor can offer good performances were proven. Furthermore, by means of modulating the duty ratio of the driving signal, charging pressure control is possibly carried out and its possibility was tested by experiment results.
Development of an Accelerated Ageing Test for Hydraulic Spool and Poppet Valves
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
O. Reinertz and K. Schlemmer and J. Schumacher and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 457-469,
März 2010
view abstract
Although proof of component reliability is compulsory for safety-related parts of control systems and essential in assessing the suitability for a particular application, no prediction models for hydraulic valves are available. Since operating conditions in field use very often fall short of manufacturer specifications, a correlation between operating conditions and valve wear is required to allow general reliability predictions. The research efforts presented in this paper thus aim at developing a mathematical model of wear in hydraulic directional spool and poppet valves and to provide valve manufacturers with a standardised short-time test set-up and procedure for accelerated ageing. Firstly, the relevant wear mechanisms and parameters are identified and discussed. An accelerated ageing test design is proposed that encompasses a hybrid multi-pass concept for contamination control as well as an optimised valve loading concept for increased efficiency and flexibility of the test procedure, and an approach for evaluation of wear dependent valve characteristics. Principles, design, and implementation of an experimental set-up are presented.
DEVELOPMENT OF AN AUTOMATED CAMBER CONTROL SYSTEM FOR THE ROUGHING STANDS OF A HOT STRIP MILL
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
R. Montague and J. Watton and K. Brown,
2002, Juli 2002
view abstract
This paper outlines the research activities carried out during the first eighteen months of a four-year Engineering
Doctorate programme in the field of fluid power control. It describes the approach taken towards the control of
camber during hot rolling of steel slabs. The project builds on previous academic and industrial research into camber
that has demonstrated tilting the rolls in the stand can counteract camber. A major contribution to advance
understanding, prediction and control of this phenomenon is data arising from a novel Slab Geometry Measurement
System. This system, recently commissioned in the hot mill at Corus - Port Talbot (UK), enables a full
quantification of slab geometry. This paper describes how production of a straight bar is to be achieved, involving
feeding forward slab geometry measurements into a model of camber generation, from which appropriate corrective
actions can be determined. A suitable control arrangement for this method of camber suppression is introduced.
Development of an expert system for electrohydraulic motion control design
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
K. Schlemmer and H. Murrenhoff,
2008,
pp. 259-268,
September 2008
view abstract
Electrohydraulic motion control is capable of delivering superior performance in many applications. Yet, it suffers from a high degree of complexity and strong demands on the designer’s expertise, often resulting in suboptimal solutions or avoidance. The approach presented in this paper aims to counteract the problem by providing necessary assistance to engineers not being sufficiently familiar with fluid power technology.
With respect to the large extent of complexity, uncertainty, and heuristic knowledge contained in servohydraulic systems design, a knowledge-based approach is adopted. In this context, four types of knowledge are distinguished: First, the structural representation of hydraulic motion control systems in general, including components and concepts as well as their functional properties and relations. Second, the knowledge about the information that is required to define and solve a given motion control problem. Third, procedural knowledge about routine tasks performed to solve partial problems. Fourth, ‘if–then’ rules linking logical conditions with decisions, selections, and actions, such as specification of a suitable control strategy depending on system and load characteristics.
The paper demonstrates how these knowledge types are incorporated into a software framework aiming to provide two results: a flexible expert system framework, which can easily be extended and adapted to specific needs, and a standard knowledge base for designing position-controlled hydraulic linear drives.
The first objective is achieved by means of three separate software tools: Protégé, an open-source ontology editor for structural knowledge acquisition, GraCE (Graphical Construct Editor), a custom-made rule and routine editor for heuristic and procedural knowledge acquisition, and HyDDAs (Hydraulic Drive Design Assistant), an expert system framework for knowledge processing and interactive performance of the design task.
The second objective encompasses acquisition of technical expertise on servohydraulic cylinder drives from literature, expert interviews, and theoretical or practical analyses.
Development of a Novel High Pressure Electronic Pneumatic Pressure Reducing Valve
Xu Zhipeng and Wang Xuanyin,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Januar 2011
view abstract
Pressure reducing valve (PRV) is one of the critical components in high pressure pneumatic systems. Nowadays, manually operated PRVs have been widely used, but there is still no universal electronic PRV. Thus, we proposed a novel high pressure electronic pneumatic pressure reducing valve (EPPRV) whose inlet pressure (pi) is up to 31.5 MPa. The EPPRV mainly consists of a poppet structured pilot valve and a piston structured main valve. A proportional electromagnet was used as the command element, and a pressure closed loop, rather than a force closed loop controller, was designed. First, the mechanical design and functionality of the EPPRV are carefully analyzed. Then, a mathematical model is built up, and the working characteristics of pressure, flow rate, and frequency response are simulated. Finally, the test bench is introduced, and detailed experiments are carried out. Simulated and experimental results are highly consistent within output pressure (po) ranging from 8 MPa to 25 MPa and load flow rate (qld) ranging from 60 g/s to 650 g/s, which verifies the feasibility of the novel structure and the validity of the mathematic model.
Development of an Ultra Fast Emergency Stop Valve
Proceedings of the 18th International Conference on Hydraulics and Pneumatics
B. Steiner and R. Scheidl and G. Hametner,
2003,
volume 1,
pp. 214-223,
view abstract
The paper describes the conceptual design, simulation, and experimental results of a 2/2-way-poppet-valve with an integrated pilot valve and an additional metering edge in the cartridge element. The principal requirements for the valve are: High flow rate and a response time less than 2 ms. The basic idea is to use a 2/2-way-cartridge-valve for the main stage and a closely integrated pilot valve, in order to reduce the hydraulic capacitance. Standard 2/2-way-cartridge-valves have a very high nominal flow rate, but they are too slow. The pilot valve is a normally open 2/2-way-seat-valve with a solenoid actuation. The nominal flow rate of the pilot valve is very small, due to the short stroke of the solenoid. The actuation force of the solenoid will be controlled by a pulse width modulated voltage signal. This technology allows to switch off the current of the solenoid very quickly. In this combination the cartridge valve and the pilot valve do not meet the required response dynamics. Therefore, an additional positive feedback metering edge was integrated in the poppet of the cartridge element. The flow rate of this edge is very high. If the poppet opens, the positive feedback edge opens as well and the oil from the back side of the cartridge valve deflates very quickly. As a result of the fast pressure reduction at its back side the poppet opens in a very short time. The emergency stop valve is used to immediately release the pressure of a hydraulic cylinder. It is directly mounted on the top of this cylinder and the outlet port is directly connected to a low pressure reservoir. The advantage of this design is the minimised hydraulic inductivity, a prerequisite for the intended fast pressure release. This valve provides much faster response than conventional cartridge valves at the cost of an increased leakage at the positive feedback metering edge. Keywords: 2/2-way-poppet-valve, integrated pilot valve, positive feedback metering edge
Development of a Picking Device of an Orange Harvesting Machine
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Raparelli and P. B. Zobel and F. Durante,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 335-339,
April 2005
view abstract
This paper presents the development of an innovative machine to harvest oranges. The starting idea is to pick the orange without a system to know its position on the tree. The architecture of the machine as well as the design and the construction of the first prototype, pneumatically driven, are shown. The first experimental tests carried out in laboratory with the prototype are described, jointly with the cutting tests on the stalk of oranges.
DEVELOPMENT OF A PNEUMATIC FORCE-DISPLAY (APPLICATION TO A MASTER-SLAVE SYSTEM)
H. Yamada and S. Kudomi and T. Muto,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 41-48,
April 2003
view abstract
In this study we deal with a bilateral master-slave system composed of a pneumatic force-display as the master and
a hydraulic servo system as the slave. In such systems the force-display must play two roles as master: first as a reference input device to the slave and second as a force-display device. The first purpose of this study is to develop a pneumatic force-display that consists of a pneumatic servo system. To achieve this, it is necessary to solve a problem called back-drivability, a characteristic of pneumatic servo systems. The second purpose is to investigate the compatibility of our thusly developed force-display with some representative methods of bilateral master-slave control systems in conventional use. In experiments to confirm such compatibility, the sensibility of load forces is estimated based on a master-slave system equipped with a spring to serve as a load. The experiments confirm that the developed forcedisplay would be applicable to conventional methods of bilateral master-slave systems.
Development of a Pressure−compensated Flow Control Valve for Water Hydraulics
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
K. Suzuki and E. Urata,
2007,
volume 2,
pp. 47-60,
Mai 2007
view abstract
This paper describes development of a pressure-compensated flow control valve for water hydraulics. A pressure-compensation valve with two throttles in series was installed to suppress cavitation. The pressure-compensation valve has hydrostatic
supports to reduce the wear of sliding parts and has a viscous damper to suppress vibration of the valve. The developed flow control valve has adjustable flowrate range of 2.5-20 L/min within the pressure range of 2-14 MPa. Although the leakage through the hydrostatic supports exists, discharge flowrate is almost constant. Flowrate variation to the average flowrate is about 5 % in the experimental results. The static characteristics show no hysteresis. In addition, the valve does not radiate cavitation noise in the range of experiment.
DEVELOPMENT OF A QUIETER VARIABLE-DISPLACEMENT VANE PUMP FOR AUTOMOTIVE HYDRAULIC POWER STEERING SYSTEM
E. Kojima,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 5-14,
Juli 2003
view abstract
In an automotive hydraulic power steering system a variable-displacement vane pump that is equipped with a control
device for adjusting the eccentricity of the cam ring and thus pump delivery flow rate according to the pump rotational
speed (i.e. vehicle speed) is gradually being used for energy saving in place of a fixed-displacement vane pump. However,
fluid-borne noise radiating into the passenger compartment has greatly increased following this replacement, and,
therefore, countermeasures to reduce pump source flow ripple have been required more than anything else to further
spread its usage. This paper reports on development research of a quieter (low fluid-borne noise level) variable-
displacement vane pump for HPS systems. First, it is indicated based on both experimental measurements and
simulation analysis of pump source flow ripple that the excessive increase of fluid-borne noise produced by existing
variable-displacement vane pumps equipped with a cylindrical cam ring is mainly caused by vane bounce occurring in the
trapping sections near the bottom dead center, which is difficult to prevent when a conventional cylindrical (completely round profile) cam ring is used. Next, a new cam ring profile for preventing vane bounce called a “modified profile cam ring” is proposed and its effectiveness is examined by noise tests in the passenger compartment of a real car as well as measurements of pump source flow ripple in a bench test circuit. The proposed cam ring is found to be successful in
reducing fluid-borne noise to at least the level of a fixed pump. The newly developed types of pumps have already been
put into practice in several kinds of automobiles.
DEVELOPMENT OF A ROBUST CONTROLLER FOR A PRESSURE CONTROL UNIT
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
A. Bootz and B. Stoffel,
2002, Juli 2002
view abstract
The design of controllers for fluid power systems is often difficult to configure due to the non-linear
effects of the components. The objective is not only stability but also the achievement of a defined control
performance. The presented paper describes the controller-design for a non-linear system with help of
the μ-Synthesis. Described is how a non-linear behaviour, e.g. dead-time, variable amplification and
pressure dependant natural frequencies, is implemented into the control design. This is achieved by
linearly modelling the parametric uncertainty with the help of Linear Fractional Transformation.
Presented is also the H∞-Method, which is needed to comprehend the μ-Synthesis. Also the μ-Analysis is
described which is a necessary tool for understanding robust stability and robust performance. Finally,
the D-K iteration is introduced, and it is shown how this computational method leads to an optimal
controller for the non-linear system.
Development of A Self−energising Electro−Hydraulic Brake (SEHB) for Rail Vehicles
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
M. Liermann and C. Stammen,
2007,
volume 3,
pp. 9-23,
Mai 2007
view abstract
This paper presents the innovative concept of a Self-energising Electro-Hydraulic Brake (SEHB) which is developed at IFAS for a railway application. Its advantages over conventional air brakes are high dynamics, the possibility to control the actual
retarding torque, more compact design, higher braking forces and higher efficiency compared to conventionally used air brakes. Due to the concept of self-energisation
only low electric power is required for brake actuation and no central hydraulic power supply is needed, thus significantly reducing design interfaces to the bogie. After
introducing the working principle of the innovative SEHB system, some safety features are presented that allow load adaptive braking and braking for long periods.
The non-linear system simulation gives insight into potential brake performance and supports the development process of the first brake prototype on the basis of an automotive
brake calliper. The paper closes with an outlook on the further development of SEHB, including a full-size prototype for tests on a brake test rig for heavy rail vehicles.
Development of a Servomotor Driven Proportional Valve
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
M. Wiegandt,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 631-639,
März 2010
view abstract
This paper describes the development of a direct operated NG 16 (ISO 4401-07-07-0-05) proportional valve. The valve is driven by a high-performance brushless servomotor which required the development of a completely new transfer mechanism to convert the rotary movement of the motor into a translational movement of the spool. After explaining the motivation and the requirements for the development, the paper describes the evolution of the new transfer mechanism as well as the customized design of the motor that was necessary to fulfill the requirements. Finally, measurement results of the prototype valve are given to show the dynamic performance of the valve.
Development of a Simulation Model of the Main Hydraulic Components and System for Metal Diaphragm Type Hydrogen Compressor
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Y.-B. Ham and S.-N. Yun and K.-Y. Ahn and D.-M. Kim and B.-S. Kwon,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 483-493,
März 2010
view abstract
The hydrogen compressor system with metal diaphragm is operated by oil hydraulic system. The oil hydraulic system of metal diaphragm type hydrogen compressor is consists of gas head, metal diaphragm, oil head, oil compensating pump, relief valve and plunger piston, etc. In this study, a dynamic simulation model of the hydraulic system and main components are developed using commercial software AMESim tool, such as a radial piston type oil compensating pump model, a high speed and a high pressure relief valve model and crank shaft driven plunger piston model. Also a dynamic simulation results are presented the operating characteristics of main hydraulic components and hydraulic system.
Development of a Test Method to Examine the Fuel Characteristic Influences on Reliability of Commercial Burner Pumps with a Tribological Test Apparatus
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
J. Lukito and O. van Rheinberg and K. Lucka and H. Köhne and S. Seehack and L. Lucks,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 493-499,
März 2010
view abstract
A tribological test apparatus was constructed to verify the reliability of fuels in commercial oil burner pumps within 24 h. In the apparatus the normal condition in a pump such as tribology and thermal stresses are simulated. The main components of the apparatus are three test specimens, which perform an axial stress test and a radial stress test as well as a combination of both. The variables such as the contact pressure, temperature, revolutions per minute, operating cycle and the form of the specimen can be adjusted to meet the expectation of the experiment. To classify a critical fuel, the torque is recorded during the whole test, especially before and after a 16 h intermittent operation. The difference between the both start-up torque values is the main criteria to determine the fuel as a critical one. The apparatus has to be cleaned thoroughly in a cleaning procedure with a special dissolver before each experiment. Deposits formed during the test on the surface of the test specimen can lead to an increase in start-up torque value. Only one litre of test fuel is required to detect reproducible results within a short time frame of 24 h and in comparison to other methods these advantages are interesting for establishing an in-house test method for burner and additive manufacturers.
Development of a Virtual Prototype of Piston Pump for Hydrostatic Transmission
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Zhang and L. Kasper and R. Kimpel,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 485-489,
April 2005
view abstract
An increasing demand for hydraulic pumps to provide high power density and reliability, higher efficiency, and more complicated control functions has challenged design engineers to come up with innovative design ideas which optimize the pump structures, effectively utilize material capacities, to meet the customer requirements. To minimize the risk of component failure and reduce the cost for prototype testing in this challenging process, an intensive analysis utilizing a comprehensive pump model is thus critical to evaluate the pump loading and stress characteristics, and predict its dynamic performance under various operation conditions before the physical prototype is ever made.
In this paper, the dynamic performance of a closed circuit hydrostatic pump was examined under various operating speeds and system pressures. Advanced modeling and analysis tools such as Pro/Engineer, ADAMS, and NASTRAN were used to evaluate load condition and stress level of critical components. These load and stress information were used in turn to construct a flexible body pump model, in conjunction with the hydraulic modeling of the pump using EASY5 software, to represent a virtual prototype of the pump. The analysis of the virtual pump provided an accurate estimation of the piston/shaft loading, hydraulic flow and leakage, port plate timing, torque loss, and control forces information. It addressed some potential problems which otherwise would have been overlooked in pump design, resulted in an optimized design of high efficiency piston pump and saving of the pump development and testing time.
Development of CNC bending machine using Parallel Kinematics Mechanism (PKM)
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
T. Shirayama and K. Ichiryu and Y. Terauchi and K. Fujita,
2004,
pp. 543-549,
Juni 2004
view abstract
In recent years, push forward (MOS) bending method was proposed(1. It is suitable for high-mix
low-volume production such as trial manufacture. We built new MOS bending machine because present
machines are insufficient to produce three-dimensional shape. Our new machine uses 6-axes PKM in
bending head. This mechanism has superior rigidity and more freedom of motion to the other MOS bending
machine. In short, this bending machine has simple and flexible structure. We studied the relationship
between bending parameter and workability until now. This paper clarified the relationship between
bending force and workability.
Development of Demining Vehicle
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
K. Hamad and I. Ken,
2004,
pp. 275-279,
Juni 2004
view abstract
Since the WWI landmines have been a major problem, and civilians have been suffering landmine leftovers.
Victims increase each year all around the world, adults, children even animals cannot avoid them. At present
time people who look for the mines and defuse them, know as de-miners, volunteer to help poor countries.
Nevertheless accidents happen, and de-miners become victims due to delicate mistakes. Briefly speaking, our
project is to develop a smart vehicle that undergoes landmine clearing process with the ability to detect, dig
and defuse landmines.
DEVELOPMENT OF FIELD ROBOT (VEHICLE DEVELOPMENT AND FUNDAMENTAL RUNNING CHARACTERISTICS ANALYSIS)
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
H. Karki and K. Ichiryu and T. Yamaura,
2006,
volume 2,
pp. 379-385,
Juni 2006
view abstract
This paper describes the features of the developed field robot vehicle. This field robot could be applied in many fields
such as rescue missions, landmine clearance, exploration, agriculture, constructions and many other tasks. With a
unique steering mechanism the vehicle could steer in all directions. Steering dynamics and hydraulic properties are
observed and discussed. A new mechanism that tilts the rubber crawler has been developed. It gives the vehicle the
ability to run over obstacles such as rocks and stairs. Basic running experiments were held to observe the hydraulic
characteristic due to the load on hydraulic motors.
Development of Hybrid Control of Electrohydraulic Torque Load Simulator
Li Yunhua,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 415-419,
September 2002
view abstract
This paper carries out the thorough analysis and research on torque load simulator using electrohydraulic servo control. Aiming at the problems that existed in loading system, such as the extraneous torque, multi-channels cross coupling and parameter variation, an exact dynamic mathematical model is established, and a new kind of compound control law is proposed. The control law consists of compensation to disturbance, internal loop robust PID control, and generalized proportion-integral control to forward error. By means of this kind of control law, the robustness and tracking performance of loading system can be greatly improved, and the extraneous torque can be effectively decreased.
DEVELOPMENT OF INTELLIGENT EXCAVATOR
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
O. Karhu and J. Vilenius and J. Uusisalo and K. Huhtala,
2006,
volume 2,
pp. 369-377,
Juni 2006
view abstract
Intelligent teleoperated mobile machines have been researched at Institute of Hydraulics and Automation since 2001.
Lately attention has been paid to distribute intelligence to the attachments of the mobile machines. The objective is to
make an excavator attachment more comfortable, accurate, and safe to operate. Since an excavator with several
hydraulic cylinders is one of the most complicated hydraulic attachments, the results could be applicable to many other
types of construction machines and hydraulic attachments. A commercial hydraulic excavator with four cylinders and
mechanically activated on/off-valves was chosen as a platform. The valves were replaced with electronically activated
proportional mobile valves and a microcontroller unit was designed and built to control the valves. In previous
research the microcontroller unit was used as a simple CAN interface. In this research the intelligent properties related
to the control valve were added to the microcontroller unit. Among these properties there are dead zone compensation,
spool offset adjustment, saturation, and safety features for fault situations. Intelligent functions are described,
implemented, and tested. Future applications with closed loop control are debated.
Development of New Spiral Robot
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
R. Horiuchi and K. Ichiryu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 690-694,
April 2005
view abstract
Recently, many manipulators which are active in various industries adopt serial-link mechanism. The mechanism enables a good range of mobility, but incompatible with compact size design, The combination of both conflicting features is needed for developing a good manipulator in the future.
Therefore, in this study, we aim to produce robot arm that solves both those conflicting features.
We thought this manipulator can apply to assistant agricultural robot, and we produced the manipulator and is mating operating system.
DEVELOPMENT OF NUMERICAL MODEL FOR A SELF-LEVELING SHOCK ABSORBER
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
J. Park and J. Kwon and I. Lee and J. Park and M. Jin and T. Kim,
2006,
volume 1,
pp. 265-274,
Juni 2006
view abstract
A load sensitive self-leveling shock absorber(SLSA) for recreational vehicles is designed and manufactured.
A mathematical model for the SLSA is developed by describing equations on oil flow in the SLSA components.
Empirical equations for describing flow through piston valve assembly and the spiral groove in pump rod are
suggested. The shock absorbing performances of the SLSA, and the pumping performance of the SLSA for self-leveling
a vehicle are simulated using the developed mathematical model, and compared with experimental results. Good
agreements between the simulation results and the experimental results were shown, thereby it was ascertained that a
highly reliable mathematical model for the SLSA was established.
Development of Riding Simulator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Tsubota and K. Ichiryu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 686-689,
April 2005
view abstract
The purpose of an existing motorcycle simulator (Riding Simulator) was safe driving experience and master of the risk-aversion procedure. Therefore, it was not able to apply to the improvement and the entertainment of the driving skill. Then, we are developing the riding simulator to be able to experience a motorcycle control actually.
This research divides into the motion system and the visual system.
In the motion system, bicycle body is supported by two axes in the upper part of the parallel link motion base. Motion base input system comes from signal of bicycle body. In the input device, the load cell is installed in the seat part of the motorcycle mounted on the motion base. By this arrangement, moment balance of center of gravity is achieved. Moreover, in the steering wheel control, angle sensor was installed. For the acceleration operation, encoder was installed to sense the angle. The acceleration, deceleration and steering feeling of the motorcycle are expressed by the combination of motion base, and motorcycle body.
The head mount display is used for the visual system. The virtual space can be freely looked about with this device.
The riding simulator with real feeling is achieved by using these devices.
Development of the Energy Efficient Electro-Hydraulic System for Excavator
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
Y.-L. Cho and D.-S. Jang and K.-Y. Kim,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 127-138,
März 2010
view abstract
To meet the VOC to reduce the total operational cost, improvement of the energy efficiency is becoming more important in the mobile construction machine. But system inflexibility of the traditional hydraulic system of an excavator hinders to find out the effective solution. EPC system is proposed to change the hydraulic system into the electro-hydraulic system. This system is designed to improve the energy efficiency, while advantages of the current open-center system such as good maneuverability and quick respond are remain. With the help of new spool design process and the flow matching, pressure drop and by-pass flow rate are to be reduced. The newly developed EPC system is installed into the Doosan 22 ton class excavator and evaluated with 11.6 % improvement of the system energy efficiency.
Development of Water Hydraulic Manipulator for the Remote Handling of Heavy Duty Components
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
A. Muhammad and P. Valkama and M. Siuko and J. Mattila and M. Vilenius,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 325-336,
März 2010
view abstract
To carry out the remote handling operations in the divertor of ITER, a manipulator driven by water hydraulic actuators has been developed at the Department of Intelligent Hydraulic and Automation of Tampere University of Technology. The ITER remote handling operations impose stringent demands on the design and control of remote handling manipulators and related equipment. This paper describes the main requirements and characteristics of this Water Hydraulic MANipulator (WHMAN). The demands of safety, reliability and recoverability are addressed in the design. Additionally, the features such as load capacity and dexterity to manipulate the heavy and large components in the constricted space of the
divertor maintenance tunnel have been considered. The ongoing improvements in the manipulator to meet further requirements are also presented. In the end paper also explores the other application areas where these developments can be useful.
Development of Wearable Power Assist Device Using Curved Pneumatic Artificial Rubber Muscle
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Gao and T. Noritsugu and M. Takaiwa and D. Sasaki,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 330-334,
April 2005
view abstract
As a power assist system, this device can be directly put on like a coat because of its lightweight and soft texture. With artificial muscle as an actuator, the device is safe to human and can greatly mitigate human body's burden. With the analysis of the experimental data, this paper makes an evaluation on the support efficiency of power assistance device.
Diagnostics and Visualization in Hydraulic Press
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
S. Stormi and J. Rinkinen,
2007,
volume 3,
pp. 293-305,
Mai 2007
view abstract
Troubleshooting and adjusting of hydraulic system of plywood press lines has been problematic in plywood mills according to service reports of Raute Oyj. The knowhow of operators and service personnel has significant role in this. In this article different ways that were tested in improving the current situation are discussed. User interface of press line was used to visualize the actuation of the hydraulic system of press line and
also diagnostics was developed. In the development of diagnostics the idea has been to exploit already existing information that electrical control of press lines provides.
Differential PWM Operated Solenoid Valves in the Pilot Stage of Mini Excavators: Modeling and Identification
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
S. Tafazoli and P. Peussa and P. D. Lawrence et al.,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 93-99,
November 1996
view abstract
For computer control of the link movements in a mini excavator, the original pilot stage has to be modified. In our previous work (Peussa et al., 1995), switching on/off valves were used in the pilot stage, as an interface between the main valve and electronics. It was investigated that Differential Pulse Width Modulation (DPWM) can be used to generate the required pilot pressure. Modeling and identification of the proposed DPWM operated pilot stage is studied in this paper. Both parametric and non-parametric approaches are employed for identification. An estimated linear model is obtained for the new pilot system and its validity is checked via various tests. According to the results, the modified pilot stage has linear dynamics and is quite reliable.
Digital Clay: User Interaction Model for Control of a Fluidically Actuated Haptics Device
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
S. A. Askins and W. J. Book,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 15-28,
November 2003
view abstract
Digital Clay is a novel haptics device the purpose which is to form a continuously variable
surface that can be used to display shape data or accept shape input. It will be composed of a
large number of small fluidic actuators and an array of MEMS micro-valves. Teams are
investigating the kinematic architecture, the human interface, the control, the fluidics, and the
valve design for this device. This paper describes the development of a computer model to
simulate the device as well as human interaction with it via a simulated fingertip. The model
is developed for a conceptual architecture design that could be used in a future prototype
wherein the surface is defined by a close-packed array of slender fluidic actuators, however
other architectures are also discussed. A key element of controlling this device will be
interpreting user input. Therefore the simulations presented attempt to validate algorithms
for tracking the user’s finger and producing variable height bosses and creases in the surface.
Digital control design and simulation in hydraulics. An integrated approach
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
M. Martelli and M. Ruggeri,
2004,
pp. 349-356,
Juni 2004
view abstract
The traditional approach to control systems design with assistance of numerical simulation is usually
oriented towards the definition of an optimal control strategy in an idealized mathematical environment,
amended with a few real system elements such as input/output quantization, input sampling and time
delays.
On the contrary, some characteristic elements of the final implementation on a target industrial
application, specially in the range of low-cost microcontroller-based control systems, are neglected in
simulation, leading to a separated re-coding of the control strategy for the target application before the
beginning of the testing phase and therefore creating a gap between the concept and implementation sides
of the problem.
The proposed approach implies a more comprehensive evaluation of the real system in the simulation
environment, by means of a direct usage of the final microcontroller ANSI-C code in the simulated model;
it has been successfully applied to the EASY5 simulation environment to develop and verify an
automotive electronic control unit, based on an 8-bit RISC microcontroller, for a hydrostatic transmission.
Digital Hydraulics – Towards Perfect Valve Technology
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
M. Linjama and M. Vilenius,
2007,
volume 1,
pp. 181-196,
Mai 2007
view abstract
Digital Hydraulics is a recently developed alternative for traditional control with servo or proportional valves. The key principle is to use parallel-connected two-way on/off
valves together with intelligent control. This paper analyses characteristics of different digital valve systems. It is shown that valve system having equally sized valves is in
many senses optimal solution. The feasibility and achievable performance of this approach is discussed. It is shown that the technology has potential for ten times faster response than existing valves and good fault tolerance. Miniaturization is shown to be essential method in implementation of this kind of valve systems.
Digital Hydraulic Transformer – Efficiency of Natural Design
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Bishop, Elton,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 349-360,
März 2010
view abstract
The Digital Hydraulic Transformer (DHT) is a recently developed alternative for energy efficient hydraulic drives. Biologically inspired by the natural design of animal muscle, the DHT allows a wide range of discrete transform ratios, fast response times and high overall efficiencies. The DHT is digital at the hardware level and allows efficient, secondary controlled, four-quadrant operation. This paper discusses the technology, and summarizes main results and the current status of research and development.
DIGITAL ROBUST CONTROL OF THROTTLED VARIABLE DISPLACEMENT HYDRAULIC MOTORS IN AIRCRAFT POWER DRIVE UNITS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
O. Biedermann,
2000,
pp. 271-289,
September 2000
view abstract
The introduction of variable displacement hydraulic motors to secondary and primary flight actuation offers a
considerable potential for power optimization and saving in aircraft hydraulic systems. The application in aircraft
systems requires high safety, reliability and availability at the smallest expense possible. Therefore the
combination of a variable displacement hydraulic motor with a fixed orifice guarantees fail-passive system
behavior. The integration in fly-by-wire flight control architecture leads to digital control structures. Robust
controller design is forced because of the influence of several uncertain physical parameters during flight mission.
Moreover the significant nonlinear characteristic of the throttled VDHM affects dynamic behavior. An
integral discrete-time robust controller design methodology is presented considering specified requirements as
dynamic bandwidth, static position accuracy and stationary power drive performance. Here the parameter space
approach is used for direct sampled-data controller synthesis. A static linear state feedback controller is chosen.
All combinations of uncertain and linearized parameters leads to a multi-model problem which is solved by
simultaneous stabilization. Finally simulated and experimental results show typical operation cases and verify
expected system dynamics in time- and frequency-domain.
DISPLACEMENT CONTROLLED LINEAR ACTUATOR WITH DIFFERENTIAL CYLINDER - A WAY TO SAVE PRIMARY ENERGY IN MOBILE MACHINES
ICFP2001 Hangzhou
R. Rahmfeld, M. Ivantysynova,
2001,
view abstract
ABSTRACT
The paper introduces a new hydraulic circuit for a pump
controlled actuator with differential cylinder. The actuator
uses a constant low pressure source for the compensation
of the difference between the in- and outgoing
flow of the cylinder chambers. The pump controlled
actuator allows an improved utilization of primary energy
due to the omitted valves especially when taking
into account recovery of potential load and brake energy
and its use for other drives. The possible amount of
saved primary energy compared to today’s valve controlled
systems for general mobile machines is to be
estimated in this paper with the help of a typical working
cycle of a reference system.
KEYWORDS
Linear Actuator, Displacement Control, Energy Saving
INTRODUCTION
Considering the developments in the field of construction,
agricultural, mining and earth-moving machines, a
strong trend towards more automation of working cycles
and support of the user can be obtained. Taking the
state of the art into account then it is obvious that there
is a high demand for new electro hydraulic servo drives
which are suitable for mobile machines. This technology
demands intelligent actuators which work in a
closed control loop. Not only continuously rising fuel
costs but also increasing pollution of the environment
claim for a higher energy efficiency of the actuators
used in these machines. Today’s mobile machines
mostly contain hydraulic valve controlled drives using
an open loop control. For energy saving purpose the
constant pressure controlled pumps are very often replaced
by load-sensing controlled pumps, and consequently
load-sensing valve technology is used today.
The use of load-sensing technology for hydraulic actuators
in close loop motion control, as needed for machines
with automatic motion control, requires very
complex multi-variable control concepts. Additionally,
a greater expenditure according to sensors and signals is
necessary. An alternative concept is shown in this paper.
Distance Education MS In Engineering: Fluid Power Engineering
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
G. W. Krutz,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 579-589,
November 2003
view abstract
Purdue University’s system today is a vital educational, research and outreach enterprise. More
than 38,000 students from all 50 states and about 100 countries study at the West Lafayette
Campus and more then 29,000 are enrolled at other campuses and locations. The University
attracts more international students than any other public research university in America. Highly
regarded in national surveys, Purdue is ranked among the top public universities in the nation,
according to U.S. News & World Report.
Using Purdue’s resources and a endowment by Otto Maha, three departments at Purdue
University, Agricultural & Biological Engineering, Mechanical Engineering, and Mechanical
Engineering Technology are combining their expertise and experience to bring distance education
delivery of fluid power curriculum to allow engineering graduates in industry to learn at their
own pace and in their own settings. This knowledge dissemination and information transfer is
possible with the Maha Fluid Power Center—Distance Learning facility. Education is becoming
global via the internet and will be the future in the development of fluid power human capital.
Distributed Control Structure of Rolling Mill Based on Fieldbus
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Wang and Y. Wang and D. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 722-725,
April 2005
view abstract
With the development of rolling process, the control structure of rolling mill is improved. After summarizing the development of its relevant control theory, control technology and control instrument, analyzing the characters of distributed control system and fieldbus control system and considering the characters of rolling process, a new distributed control structure of rolling mill based on fieldbus is presented. By mean of analyzing the control structure based on fieldbus, the sketch of distributed structure of rolling mill based on fieldbus is presented, it is meet with the request of expansion, maintenance and manipulation of the rolling control structure.
DLM/FD Simulation on the Motion of a Charged Particle in a Micro-channel
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
X. Shao and Y. Zhang and Y. Liu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 389-393,
April 2005
view abstract
A distributed Lagrange multiplier/fictitious domain (DLMIFD) method for the fluid-solid interaction simulations are briefly described. And then the sedimentation of a charged particle in a micro-channel is simulated by using DLM/FD method. The results show that, when the dielectric constant of the liquid is smaller than that of the walls, there exists a metastable state in addition to the stable state on centerline for charged particle with critical charge density. At this metastable state, the particle settle vertically at an off center position.
Double Acting Hydraulic Shock Absorber at Wheel Suspension Vehicles (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
G. Koreisová and J. Koreis,
2006,
pp. 142-149,
Mai 2006
view abstract
The paper investigates the time course of the vibrations of the wheel and the vehicle body
during crossing a wedge-shaped obstacle. The tyre is modelled as a pneumatic spring with
nonlinear characteristics and non-zero coefficient of damping. The system contains a doubleacting
hydraulic shock absorber.
The wheel suspension in a vehicle consists of two levers forming a parallelogram, a spiral
spring, double-acting hydraulic shock absorber, and a wheel with a tyre.
The response for a single-acting and double-acting hydraulic absorber is compared, and the
influence studied of the vehicle velocity on the time course of vibrations of the car body above
the wheel. The hydraulic damper exerts a damping force, which has two components. The first
component is due to viscous friction of a piston in the cylinder. It is directly proportional to
the piston velocity, but is independent of the direction of the movement. The second
component is caused by the damping valves in the piston. These valves are single-acting.
Inside the damping valve there is an orifice, causing a pressure difference, which is used for
damping. This pressure difference is proportional to the square of the flow rate. The damping
force caused by the orifice is proportional to the square of piston velocity, and depends on the
direction of its movement. If the piston rod moves into the damper, the damping force is
bigger, and when it moves out, it is smaller.
The arrangement is shown in Fig. 1. The dimensions of the hydraulic damper, needed for the
calculation of the coefficients of linear and quadratic damping, are given in Fig. 2. The
dimensions of the mechanical helical spring according to ČSN 02 0601 are in Fig. 3, and its
linear characteristics is depicted in Fig. 4. The actual local deformation of the tyre in contact
with the road is tri-dimensional. For simplification, however, only the deformation in radial
direction is considered, and the tyre is modelled as a simple pneumatic spring (Fig. 5). The
properties of this spring were calculated assuming a polytrophic change of pressure and
volume. The nonlinear (progressive) static characteristics show the dependence of the force
on the tyre deformation (Fig. 6). The arrangement of the complete wheel suspension and its
simplified mechanical scheme is in Fig. 7. The wedge-shape of the obstacle and its
description by means of a ramp function are shown in Fig. 8.
Two mutually dependent equations were derived for the description of vibrations of the wheel
and the vehicle body above it. Equation (15) for body vibrations includes the influence of the
linear and quadratic damping by the double-acting damper. The influence of nonlinear
characteristics of the tyre is included in the equation for wheel vibrations. Using these
equations, a simulation model in Matlab-Simulink was created (Fig. 9). The results of
simulations are shown in Fig. 10. With increasing ride velocity, the ramp function converges
to the step function, and the response to the ramp input converges to the transient curve. The
wheel suspension with the double-action damper leads to smaller amplitudes of car body
vibrations than the suspension with a single-action damper. The influence of quadratic
damping is obvious especially on the deformation of the first amplitude of wheel vibrations.
Driving Feel Generation of the Mobile Machine Simulator with the Water Hydraulic 6-DOF Motion Platform
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
M. Rokala and H. Sairiala and K. T. Koskinen,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 367-378,
März 2010
view abstract
In this research the use of water hydraulic Stewart platform in mobile machine driving simulator is studied. The motion platform has six water hydraulic cylinders which are controlled by proportional directional valves. In previous studies problems with the movements of actuators have been noticed. This paper presents some improvements of the controllers of the water hydraulic motion platform. Because the realistic trajectory is the only way to test the suitability of water hydraulic platform, first part of this paper considers the simulation model of the mobile machine and the realization of the connection between water hydraulic 6-DOF motion platform and the simulation model. Different types of trajectories are generated according to the simulation model of the mobile machine and tested with the water hydraulic platform. In this paper it is shown that it is possible to use water hydraulic motion platform to realize driving feel for slow mobile machine.
Dual Electrohydraulic Servo Motors Synchrodrive System Using Adaptive Neural Control Strategy
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
F. Xingwu and Z. Keding and L. Qinghe,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 143-147,
November 1998
view abstract
The adaptive neural control strategy is employed for the characteristics and specifications of the middle gimbals synchrodriven by the dual electrohydraulic servo motors in the simulator with three axes, the decoupling is implemented. Simulation results show that this strategy, because of it's self-learning and inherent nonlinear, etc., makes the system present superior dynamic performance and adaptability. The superior synchromotion performance of the system has been obtained.
Dynamical performance of a fast magnetorheological (MR) valve
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
J. Kostamo and E. Kostamo and J. Kajaste and M. Pietola,
2007,
pp. 399-412,
September 2007
view abstract
Magnetorheological (MR) fluid belongs to the group of smart materials whose rheological properties can be varied by application of a magnetic field. The response time of magnetorheological technology is generally considered fast. In a recent study the response time of the MR fluid was estimated to be approximately 0.5 milliseconds. However, there is remarkable variation in measured response times of magnetorheological devices in different studies. ln this paper some design considerations of a fast magnetorheological valve are discussed and a response time of less than 1 millisecond is demonstrated with an experimental valve.
Dynamic Analysis of an Electro-hydraulic Proportional Speed Control System with a Single-rod Hydraulic Actuator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J. Yang and B. Xu and H. Yang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 808-813,
April 2005
view abstract
A PID control algorithm is used to study the dynamics of an electro-hydraulic proportional speed control system (EHPSCS) with a single-rod hydraulic actuator, because the PID control algorithm is simple in operation, is characteristics of good computer real-time control, and possesses the good adaptability of changing parameters of control system and it is easily implemented in engineering applications. Experimental research on the speed control under the conditions of the different temperatures of hydraulic oil is carried out for an EHPSCS. Furthermore, the performance of the EHPSCS is analyzed through measuring the inlet pressure, the outlet pressure of the proportional valve and the pressure difference between the inlet pressure and the outlet pressure of the proportional valve. Experimental results show that the PID controller has good dynamics.
Dynamic Analysis of a Pneumatic Digital Valve through Ansys/Matlab-Simulink Cosimulation
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
M. Sorli and S. Pastorelli and A. Almondo,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 175-186,
November 2003
view abstract
In this paper an analysis of the electromechanical behavior of a pneumatic two-way poppet
digital valve controlled with PWM technique is presented. The aim is to predict the effects of
the input signal frequency and duty cycle on the valve dynamics. The magnetic circuit has
been analyzed using both a lumped-parameters model and a finite elements software. In both
cases, such results have been used to simulate the behavior of the system in the time domain,
integrating the electric and mechanical differential equations in Matlab-Simulink
environment. Simulated values of current and position of the poppet have been compared with
the experimental data measured on the valve. These comparisons show the different
approximations in lumped-parameters and finite elements models.
DYNAMIC ANALYSIS OF HYDRAULIC RECEIVERS CONTROLLED IN THE PROPORTIONAL TECHNIQUE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
I. Burszczan and E. Tomasiak,
2008,
pp. 435-444,
Juli 2008
view abstract
In the article analyses concerning the problem of decide of transitional hydraulic receivers were discussed (of the
hydraulic servomotor and the rotational engine hydraulic) steered in the proportional technique. The start-up and
braking will be dependent from the power supply and from straining receivers.
Dynamic behavior of an electrohydraulic valve: Typology of characteristic curves
F. Rovira-Más and Q. Zhang and A. C. Hansen,
In Mechatronics,
2007,
volume 17,
pp. 551-561,
Dezember 2007
view abstract
The majority of off-road vehicles employed in agriculture are equipped with a hydraulic steering. An efficient way of automating the steering mechanism of these vehicles is by controlling the electrohydraulic valve that operates the steering cylinder. Electronically-controlled hydraulic valves often behave nonlinearly and, consequently, they introduce certain complexities in the analysis of the hydraulic system. Therefore, it is necessary to understand their behavior before designing a control system that is able to auto-steer an agricultural machine safely and efficiently. The objective of this work was to characterize the performance of an electrohydraulic valve with the aid of a set of experiments conducted on a hardware-in-the-loop electrohydraulic simulator. The operation of the valve was classified in four types (I, II, III, and IV) according to the valve characteristic curves and the properties of the input signal. The phenomena of deadband, hysteresis, and saturation helped to discriminate between types. The input signal, especially its frequency, was crucial in studying the functioning of the valve. The hardware-in-the-loop simulator was fed with signals that imitated the auto-steering action. The outcomes obtained from this research provide some critically supporting information for designing high performance steering controllers for agricultural vehicles.
Dynamic Behavior of Complex Fluid-Filled Tubing Systems—Part 1: Tubing Analysis
Forbes T. Brown and Stephen C. Tentarelli,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 71-77,
März 2001
view abstract
A general transmission-matrix approach is given for finding the frequency response of linearized long-wavelength models for the vibration in systems with straight and curved fluid-filled tubes. Couplings between the fluid and wall motions include the Bourdon effect, frequency-dependent wall shear, the Poisson coupling and the effect of discontinuities. The introduction of a global transmission matrix allows nonplanar tubing systems of virtually any complexity to be analyzed, overcoming the round-off error problem that plagues the basic transmission-matrix approach for this and analogous system models. Corroborating experiments focus on the Poisson and Bourdon effects.
Dynamic Behavior of Complex Fluid-Filled Tubing Systems—Part 2: System Analysis
Stephen C. Tentarelli and Forbes T. Brown,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 78-84,
März 2001
view abstract
The pipe segments modeled in Part 1 are incorporated into a larger scheme permitting branching, fittings, valves, added masses, rigid, flexible and dissipative mechanical constraints, accumulators and various boundary conditions. The concept of the global matrix also is extended to systems with junctions and closed loops, permitting practical solution for frequency responses without round-off error problems. The procedure can be generalized to handle a broad class of systems comprising a combination of lumped elements and quasi one-dimensional distributed-parameter elements. A complex example with experimental corroboration is given.
Dynamic Constraint-Based Energy-Saving Control of Pneumatic Servo Systems
Khalid A. Al-Dakkan and Eric J. Barth and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 655-662,
September 2006
view abstract
This paper proposes a control approach that can provide significant energy savings for the control of pneumatic servo systems. The control methodology is formulated by decoupling the standard four-way spool valve used for pneumatic servo control into two three-way valves, then using the resulting two control degrees of freedom to simultaneously satisfy a performance constraint (which for this paper is based on the sliding mode sliding condition), and an energy-saving dynamic constraint that minimizes cylinder pressures. The control formulation is presented, followed by experimental results that indicate significant energy savings with essentially no compromise in tracking performance relative to control with a standard four-way spool valve.
Dynamic Effects in Mobile Manipulators with Hydraulic Systems
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
S. Michalowski and A. Sobczyk,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 349-357,
November 2003
view abstract
As an experience shows, the presence of hydraulic driving systems is the major determinant
of large-scale stationary and mobile manipulators' flexibility. Hence, especially in terms of
dynamics, the major problem is control of natural vibrations during transient state motion
because of machine's stability or during its ride to provide the required precision of position
control. The results presented in paper suggest that while modelling hydraulic drive and
steering systems for such machines, it is necessary to develop and analyse more complex
mathematical models which would include also such effects as an internal structure of the
hydraulic system on manipulator dynamic behaviour. To illustrate the problem and for the
purpose of studies, a model of a wheeled, construction manipulator carrier was taken into
consideration and analysed.
Dynamic mesh modelling of a direct acting relief valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
D. Huguet,
2004,
pp. 239-245,
Juni 2004
view abstract
The most important aspect to have account in the modelling of a pressure relief valve is the time position
dependence. This paper introduces a new test rig which is possible to get the position of the plug over the
time as well as the pressure fluctuations at the inlet. The utilization of CFD modelling is getting more
importance every time, nowadays with the use of the dynamic mesh modelling is possible to obtain the
simulated velocity contours and pressure distribution as function of boundary conditions and plug
position. Several simulations of conical plugs with chamfer or non, are presented and the results
discussed. It is also presented the reattached or separated flow configuration depending on plug position,
which is an important factor of the vibrational behaviour of these kinds of components.
Dynamic Model for a Dome-Loaded Pressure Regulator
A. Nabi and E. Wacholder and J. Dayan,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 290-297,
Juni 2000
view abstract
A generalized physical model describing dynamic behavior of a fast-acting, dome-loaded, gas pressure regulator was developed. The regulator is designed to respond quickly to command changes, and to operate over a wide range of flow rates and pressures. The analytical lumped-parameter model developed consists of a set of nonlinear, first-order, ordinary differential equations with respect to time, accounting for mass and energy conservation at regulator outlet, command dome and internal feedback compartments. It also accounts for the equation-of-motion for the poppet and the control piston-assembly. The numerical solution, based on a Runge–Kutta method, is amenable to an extensive parametric study of regulator performance, and serves as a useful analytical tool for designing new pressure regulators. Several tests were performed on a fast-acting regulator to verify the physical model. Good agreement between predictions and measurements was obtained. The effect of several parameters, geometrical and operational, on regulator performance was studied.
Dynamic Modeling of a Magnetorheological Rotation Rheometer
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
E. Kostamo and J. Kostamo and J. Kajaste and M. Pietola,
2010,
pp. 27-37,
September 2010
view abstract
Magnetorheological (MR) fluids are widely utilized in applications requiring good dynamic performance. When striving to apply the magnetorheological technology in high frequency devices and to define the dynamic range of the MR fluids there is a need to develop new methods to study the response time of MR fluids. Although the dynamics of the MR fluids has been proven to be fast, the precise measurement of the fluid's response time has turned out to be a challenging task. To achieve more reliable results, attention needs to be paid to the selection of the measurement method and all the functional components of the measurement set-up need to be modeled.
The contribution of this study is to publish a new construction and simulation model of a magnetorheological rotation rheometer. The reserch device is designed to be used in the study of the response time of the MR fluid and in the fluid model development. The constitutive idea of the designed rotation rheometer is to be able to directly detect the change in the fluids apparent yield stress by measuring the transmitted torque between the rotor and stator of the rheometer. To eliminate the influence of the mechanical construction of the rheometer a simulation model will be developed based on a CAD-model and validated by impulse measurements. Applicability of the developed rheometer in response time measurements of the MR fluid will be discussed and the procedure of the future measurements will be outlined.
Dynamic Modeling of a Monopropellant-Based Chemofluidic Actuation System
Navneet Gulati and Eric J. Barth,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 435-445 ,
Juli 2007
view abstract
This paper presents a dynamic model of a monopropellant-based chemofluidic power supply and actuation system. The proposed power supply and actuation system, as presented in prior works, is motivated by the current lack of a viable system that can provide adequate energetic autonomy to human-scale power-comparable untethered robotic systems. As such, the dynamic modeling presented herein is from an energetic standpoint by considering the power and energy exchanged and stored in the basic constituents of the system. Two design configurations of the actuation system are presented and both are modeled. A first-principle based lumped-parameter model characterizing reaction dynamics, hydraulic flow dynamics, pneumatic flow dynamics, and compressible gas dynamics is developed for purposes of control design. Experimental results are presented that validate the model.
Dynamic Modeling of a Piezoelectric Actuated Fuel Injector
Chris A. Satkoski and Gregory M. Shaver and Ranjit More and Peter Meckl and Douglas Memering and Shankar Venkataraman and Jalal Syed and Jesus Carmona-Valdes,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
September 2011
view abstract
As engine designers look for ways to improve efficiency and reduce emissions, piezoelectric actuated fuel injectors for common rail diesel engines have shown to have improved response characteristics over solenoid actuated injectors and may allow for enhanced control of combustion through multipulse, closely spaced injections or rate shaping. This paper outlines the development of an 11 state simulation model for a piezoelectric fuel injector and associated driver that can be used for injector design and control system verification. Nonmeasureable states of the model are plotted and analyzed, while measurable quantities including injection rate, piezo stack voltage, and piezo stack current are validated against experimental injector rig data for two different rail pressures.
Dynamic Modeling of Capsule Separator for Control of Hydraulic Capsule Pipelines
Hongliu Du and Satish S. Nair,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 233-241,
Juni 1999
view abstract
Hydraulic capsule pipelines concepts are novel as compared to existing commercial pipeline systems. The complexity of such novel systems places greater demands on sensing, automation, and control strategy design for such systems as compared to existing commercial pipeline systems. These issues, as well as hydraulic design automation and control strategies, are reported. A novel capsule separator design has also been proposed to ensure reliable functioning of `booster' stations for such pipelines. Detailed dynamic modeling of the proposed capsule separator is performed for generating design and control guidelines. Validation of the overall hydraulic capsule pipeline design and control, and limited validation of the proposed capsule separator subsystem, are provided using a prototype hardware computer controlled pipeline model.
DYNAMIC MODELLING AND PARAMETRIC STUDIES OF AN INDEXING VALVE PLATE PUMP
J. Cho and X. Zhang and N. D. Manring and S. S. Nair,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 37-48,
Dezember 2002
view abstract
The swash-plate in a variable displacement pump experiences very large forces and moments that try to dislocate its
position; therefore, a large device is required for adequate control. In this paper, the dynamics of an alternative pump
design using an indexing valve plate to position the swash-plate are reported. The indexing valve plate design is aimed at controlling the pressure transition for a piston, which is moving from a high-pressure port to a low-pressure port. In this paper, the governing equations for the pump are derived and the detailed open-loop and parametric studies, which are necessary for understanding the overall dynamic characteristics of the pump, are reported. Also, full nonlinear and simplified modelling approaches for the system are compared.
Dynamic Modelling of CVT Power Train
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: ISBN: 978-952-15-1758-7,
M. Erkkilä,
2007,
volume 1,
pp. 19-37,
Mai 2007
view abstract
The paper presents a simulation model for a CVT Power train, consisting of sub models for diesel engine, hydrostatic, CVT gearbox and clutches, wheel-road-connection and vehicle. The main design features and verification of the sub models are presented. The model is designed for virtual design and testing of the CVT control unit. The main control function requirements are presented. The power rain model can also be used in “Hardware in the Loop” simulation for testing the designed CVT control unit. The Hardware in the Loop special requirements for simulation model is briefly mentioned.
Simulation examples are presented and analysed in the paper.
Dynamic Model of CVT Power Train
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
M. Erkkilä,
2007,
volume 1,
pp. 19-37,
Mai 2007
view abstract
Dynamic modelling of CVT Powertrain. The paper presents a simulation model for a CVT Powertrain, consisting of submodels for diesel engine, hydrostatic, CVT gearbox and clutches, wheel−road−connection and vehicle. The main design features and verification of the submodels are presented. The model is
designed for virtual design and testing of the CVT control unit. The main control function requirements are presented. The powertrain model is also used in "Hardware in the Loop" simulation for testing the designed CVT conrol unit. The HIL special requirements for simulation model are briefly mentioned. Some simulation examples are shown.
Dynamic Performance of Excavator Joystick Driven by Pneumatic Cylinder (Basic Study of Robot for Excavator)
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
Y. Kaneko and K. Ichiryu,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 255-260,
November 2003
view abstract
Hydraulic excavator is universal construction machine for versatile works. Automation or
unmanned operation of hydraulic excavator is desired for dangerous work at hazardous area.
For one measure of automation of excavator, we are planning to mount automatic pneumatic
robot on existing standard machine. By this method rapid change from human operator to the
automated robot operator becomes possible in case of disaster without using special machine.
Concerning excavator operation combined maneuvering of multi joysticks is necessary. Also,
fine movement of joystick is indispensable for robot operation, too. Considering above
situation, as a first step to develop automatic robot we are evaluating travel lever actuating
system by pneumatic cylinder. To achieve accurate positioning of joystick we tested two kinds
of typical pneumatic servo valves of linear and rotary construction with different control
method such as PID and I-SAC.
Dynamic Redesign of a Flow Control Servovalve Using a Pressure Control Pilot
Perry Y. Li,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 428-434,
September 2002
view abstract
In this paper, the dynamic performance of an unconventional two-spool flow control servovalve using a pressure control pilot is analyzed. Such valves are less expensive than typical servovalves but also tend to be limited in their dynamic performance. Based on a previously developed eight state nonlinear model, we develop a simplified linear model which is able to capture the essential dynamics of the valve. Using root locus analysis method, the limitation in dynamic performance is shown to be due to a "zero" introduced by the structure of the interconnection of the subsystems. Design parameters that move the zero further to the left half plane, and do not adversely affect other steady-state criteria are identified. The effectiveness of these parameters to improve the dynamic performance is demonstrated. This analysis demonstrates how the structure of the interactions between subsystems in a dynamic component, such as a hydraulic valve, can critically limit the dynamic performance of the component.
Dynamic response of a hydraulic servo-valve torque motor with magnetic fluids
S. Li and Y. Song,
In Mechatronics,
2007,
volume 17,
pp. 442-447,
view abstract
As magnetic fluids (MF) show higher saturation magnetization and larger viscosity when exposed to a magnetic field, large damping forces or resistance will be exerted on the armature of a hydraulic servo-valve torque motor by magnetic fluids if they are filled into the working gaps of the motor. This paper focuses on the application of magnetic fluids in a hydraulic servo-valve torque motor, especially the influence of magnetic fluids on the dynamic response of the motor. After introducing the working principle of the torque motor with magnetic fluids, the dynamic mathematical models of the torque motor and magnetic fluids are presented. The torque working on the armature introduced by magnetic fluids is analyzed. In order to study the influence of magnetic fluids, dynamic response of the torque motor is simulated and tested when magnetic fluids are applied or not in the motor. Simulation and experimental results show an obvious influence of magnetic fluids on the dynamic response of the hydraulic servo-valve torque motor.
Dynamic Simulation of a Large Hydraulic Capsule Pipeline System
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
H. Du and S. S. Nair,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 61-66,
November 1997
view abstract
A booster station in a long distance hydraulic capsule pipeline is simulated mathematically to study the hydraulic transients caused by the periodic closing and opening of the valves present in the pipeline design (Du and Nair, 1995, 1996). The Method of Characteristics is used for the dynamic simulation studies, performed to help design and size part of the booster station subsystem. Several modifications to the pump bypass station configuration of the booster station have been studied. Under the criterion of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber are found to be optimal. A valve stroking method is designed to eliminate column separation and the design results in an acceptable flow reversal in the main pipe. The simulation results match in general behavioural terms with limited experimental studies performed on a small scale experimental capsule pipeline system.
DYNAMIC SIMULATION WITH TEST VERIFICATION FOR SOLVING AND UNDERSTANDING FLUID POWER SYSTEM PROBLEMS
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
R. Rahmfeld and O. Meincke,
2006, August 2006
view abstract
This paper presents how Sauer-Danfoss Propel is using the method of dynamic simulation and advanced testing for
verification. It is used as well for understanding of fluid power systems during the development phase as solving problems
in customer applications. For this purpose, the main components of a transmission are modelled, whereby special
attention is paid to rotating kit losses in order to ensure a suitable comparison to measurement results from the machine.
The final simulation model allows the testing of different operating conditions, and by this ensuring a robust design, and
much more important, the physics behind the model can be understood in an effective way.
Dynamics of a Large Scale Hydraulic Capsule Pipeline System
Hongliu Du and Satish S. Nair,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 191-195,
März 2002
view abstract
The dynamics of a booster station, which is critical for the control of a novel, long distance, hydraulic capsule pipeline, is simulated mathematically for design studies and control of the hydraulic transients caused by the valve actuators in the system. Several modifications to the pump bypass station configuration of the booster station have been studied. With the objective of eliminating column separation and reducing flow reversals, a configuration with several centrifugal pumps connected in series, and a carefully sized air chamber is found to be a viable design. A valve control method is designed to eliminate column separation and the design results in acceptable flow reversal levels in the main pipe. The simulation results match with trends in limited experimental studies performed on a small scale experimental capsule pipeline system.
Dynamics of Cilia-Based Microfluidic Devices
J. Kongthon and J.-H. Chung and J. J. Riley and S. Devasia,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
September 2011
view abstract
This article models the dynamics of cilia-based devices (soft cantilever-type, vibrating devices that are excited by external vibrations) for mixing and manipulating liquids in microfluidic applications. The main contribution of this article is to develop a model, which shows that liquid sloshing and the added-mass effect play substantial roles in generating large-amplitude motion of the cilia. Additionally, experimental mixing results, with and without cilia, are comparatively evaluated to show more than one order-of-magnitude reduction in the mixing time with the use of cilia.
Dynamics of Mechanical Hydraulic Junctures of Aircraft Controls (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
M. Vyskočil and K. Třetina,
2006,
pp. 115-120,
Mai 2006
view abstract
The use of the hydraulic boosters in the modern aircraft control systems has become very
popular at present time. The extreme requirements to the aircraft flight characteristic and to
the rigidity of the airframe also reflect on the extreme requirements to the properties of the
hydraulic boosters controlling the rudder. The hydraulic booster is built into the proper part
of the airframe and the piston rod motion is transmitted through the leverage to the rudder.
The dynamic properties of the control system are given first of all by constructional and
operational parameters of the booster structure and by linking the rudder with the booster.
Due to the elasticity of the airframe and the booster some undesirable aeroelastic phenomena
may occur and their effects may impair the aircraft controllability and also result in the
airframe fatigue damage. This article focuses on the influence analysis of some booster
operational and constructional parameters over the change of its dynamic properties. The
analysis is carried out by means of the physical-analytic method of describing the booster
operation and is aided by computer modelling. The whole analysis takes into account the
parameters of the booster that is a part of the longitudinal control system of an aircraft. The
knowledge of how the changes of the constructional and operational parameters influences
the dynamic properties of the booster enables the dimensions of its individual parts to be
tailored corrective. It also enables the operational and maintenance instructions to be
specified. The computer modelling is a suitable way to determine the quantitative dependence
of the booster dynamic properties on the constructional and operational parameters.
DYNAMIC STABILITY OF A PIPE SUBJECTED TO A PULSATING FLOW
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
G. Catellani and M. Milani and F. Pellicano,
2002, Juli 2002
view abstract
Power transmission pipes are widely present in industrial applications. Moreover, the physical and mathematical model
describing the dynamics of a pipe is similar to that of many mechanical systems such as heat exchangers high-speed
magnetic tapes, band saw blades, aerial cable threadlines, and sheet production processes. All previous systems are
axially moving systems. The dynamic behaviour of an axially moving system is greatly influenced from the presence of
the internal flowing fluid, which affects the pipes dynamics and stability. When a critical value of the axial speed is
reached, the first linear natural frequency vanishes; the straight equilibrium position loses stability and bifurcates into new equilibrium states. In the sub-critical speed range, all natural frequencies decrease as the axial speed increases and the vibration modes are complex. In actual operating conditions, pipe lines are subjected to many external disturbances, such as external excitations or dynamic disturbances exerted by the flow fluctuations induced by a volumetric pump.
Some example of pump-pipes interactions can be found in literature, that highlight the great influence of pump
irregularity on lines stability and system noising. When an oscillating external excitation causes a resonance, very
dangerous conditions can be met and the axially moving continuum can undergo to catastrophic failures. The presence
of an internal flow can cause divergence and flutter type instabilities. The fluid structures interaction analysis requires a deep investigation of the internal velocity field
Dynamic Testing of Servohydraulic Equipment
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
P. Drumea and M. Comes and I. Dutu,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 485-492,
März 2010
view abstract
In modern electro-hydraulic automation systems it is often used as control equipment one or more servovalves, a type of hydraulic equipment that has a proportional dependency between the driving current and the hydraulic flow, at constant pressure loads. The paper will describe an informatics platform used in laboratory testing for identifying an equivalent transfer function of a two-stage servo-valve. The results of the laboratory tests will be compared, for accuracy, with the data given by the manufacturer of the servovalve.
DYNAMIC THERMAL MODEL OF A DISCHARGING PROCESS OF A PNEUMATIC CHAMBER
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
R. De Giorgi and E. Bideaux and S. Sesmat,
2006,
volume 2,
pp. 571-583,
Juni 2006
view abstract
The purpose of this paper is to propose a thermal model for the discharging process of a pneumatic chamber that
enables the average pressure and temperature in the tank to be obtained accurately in simulation. The heat transfer
takes place by the combining effect of three different mechanisms: combined free-forced convection between the gas
and the inside tank wall, heat conduction and storage in the wall, free external convection between the outside tank wall
and the environment. By using the adequate thermal exchange models, based on empirical dimensionless laws, the heat
transferred power can be computed accurately.
Ecological Fluid Power Units-Ekoextrem (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
O. Ožana and M. Ožana and M. Kirnig,
2006,
pp. 75-82,
Mai 2006
view abstract
The target of EUREKA – EKOEXTREM project solution in the years 2004 ÷ 2005, called
„Ecological power unit for extreme climate conditions“ was the result of industrial research
and development enclosed in below-mentioned stages of solution.
1. Industrial research and development of ecological power units
2. Fabrication and experimental verification of the prototypes
In the framework of the solution stages there were proposed electro-hydraulic power units
with ecological medium, pneumatic power units and control electronic regulation system for
alternative execution of power units.
Based on prepared production and design documentation this equipment has been fabricated
and completed at the workplace VCPA (Research Center of Industrial Applications) of BIC
Ostrava – see picture 1, where the prototypes have been experimentally verified.
Experimental measuring has been performed in accordance with proposed methods of
measuring at extreme climate conditions–40 °C ÷ +80 °C that were simulated in conditioning
chamber, where the actuators of fluid power units have been situated.
On the basis of the results estimation of measuring and dynamic and regulation parameters
of experimental equipment, criteria assessment of usability limits and application of separate
power units has been performed.
In the finishing year of the project EUREKA solution, i.e. 2006, it will be solved a partial
stage called „The selection of optimal alternative, product line“ with concretization of the
project and design solution of fluid power units for concrete industrial applications.
EFFECT OF CAVITATION IN WATER HYDRAULIC POPPET VALVES
S. Oshima and T. Leino and M. Linjama et al.,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 5-13,
November 2001
view abstract
In this paper, cavitation in water hydraulic poppet valves is investigated by an experimental method with a half cut
test model. The situation of cavitation appearance, the effects of cavitation on the characteristics of flow rate, noise
level, pressure distributions and the boundary of inception of the cavitation are investigated. Comparison between a
poppet valve with sharp edged seat and another, which has a length on the seat, is made. The effects of change in the
shape of the seat are discussed as well as the effect of cavitation appearance. As a result, it is revealed that the sharp
edged seat valve is less influenced by the cavitation on its characteristics.
EFFECT OF CONTROLLER IN REDUCING STEADY-STATE ERROR DUE TO FLOW AND FORCE DISTURBANCES IN THE ELECTROHYDRAULIC ACTUATOR SYSTEM
E. Sampson and S. Habibi and R. Burton and Y. Chinniah,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 57-66,
August 2004
view abstract
This paper pertains to the nonlinear control of a high-precision hydrostatic actuation system known as the Electro-Hydraulic Actuator (EHA). It describes the action of the controller in reducing the steady state error resulting from flow and force disturbances. The EHA uses inner-loop pump velocity feedback to achieve an unprecedented level of accuracy
for a hydrostatic system. A published mathematical model of the EHA is reviewed and expanded to produce an equation that predicts the response of the EHA to both desired inputs as well as flow and force disturbances. This equation suggests that the use of a proportional outer-loop controller should result in steady-state error as a result of these disturbances, but that a PI outer-loop controller should eliminate the steady-state error. Experimental results from a prototype of the EHA demonstrate that due to the nonlinear friction present in the actuator, the use of a conventional proportional or PI controller is not sufficient to effectively deal with these disturbances. However, a nonlinear proportional
outer-loop controller does result in a substantial performance improvement in regards to disturbance rejection for positional
accuracy. Experiments conducted on the prototype using the nonlinear controller reveal that it is capable of a positional
accuracy of 1 μm for a load of 20 kg.
Effect of Fiber Additives on Flow in Journal Bearings
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Zhanhong and L. Jianzhong and W. Fenghui and L. Bingru,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 284-291,
April 2005
view abstract
The flow with semi-concentration fiber additives in journal bearings is investigated numerically based on the self-consistent continuum theory. A special treatment of the stress aroused by the fibers is combined with the iteration scheme to solve the equations of the fiber suspensions. The results show that the role of the stress aroused from the fiber vanishes near the inner cylinder because the fibers tend to align with the wall, however, the anisotropic characteristics of the stress field are obviously observed near the outer cylinder. The influence of the fiber additives on the vortex in the flow is related to the parameters in the flow and the characteristic parameters of the fiber such as the aspect ratio and volume fraction.
Effect of Fluid Inertia on Stability of Hydrodynamic Bearings
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
B. C. Majumdar and S. K. Kakoty,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 39-57,
November 2003
view abstract
Owing to high speed of present day machinery, such as I.C. Engines, turbo-machines, pumps,
and increasing trend of using low viscosity lubricants e.g., synthetic lubricants and water,
there may be certain situations when fluid inertia forces are of the same order that of viscous
forces. In such a situation classical approach of negligible fluid inertia may not be applicable.
On the other hand, stability, especially for lightly loaded bearings, is a concern. In this
context a fresh look to the problem considering the influence of fluid inertia on the steady
state and stability characteristics of the abovementioned machines supported on
hydrodynamic journal bearings is necessary.
The governing equations are derived from Navier-Stokes equations considering that the
velocity profiles across the film remain parabolic even when fluid inertia is not negligible.
Here the momentum equations are not linearized and therefore, can be applied for any value
of inertia parameter (modified Reynolds number).
A non-linear transient analysis incorporating the film history has been performed to study the
sub-synchronous whirl instability of these bearings. Journal centre trajectories have been
obtained to find the status (stable or unstable) of the rotor-bearing system. Using this
approach the threshold of instability is determined for different operating conditions.
The study provides a better understanding of the performance of hydrodynamic bearings used
in high speed fluid machinery.
EFFECTS OF GEOMETRIC IMPERFECTIONS AND PERIPHERAL GROOVING ON GAP FLOW IN PROPORTIONAL SPOOL VALVES
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
K. Schlemmer and H. Murrenhoff,
2006,
volume 2,
pp. 421-431,
Juni 2006
view abstract
The flow fields in the annular sealing gaps of proportional spool valves are subject to the actual geometrical form of
the gap. Thus, the characteristics of gap flow can be influenced by deviations from ideal gap geometry as defined by
roundness, straightness and coaxiality of the components. Resultant forces and moments may tend to change the spool
position until, reacting on the gap geometry, an equilibrium is attained. Knowledge of the manner in which the gap flow
is affected by such variations in gap geometry is essential for the purpose of optimising pressure distribution, resulting
transverse load and leakage. To this end, a simulation model of the annular gap flow based on the 2-dimensional
Reynolds equation is presented, which is employed to analyse the aforementioned interdependencies. Peripheral
balancing grooves on the spool lands are integrated into the model as hydraulic capacities. The results are used to
evaluate the effectiveness of a particular design feature as a means of optimisation. Through parameter variation,
relevant relations are identified and design recommendations are given. An experimental verification of the simulation
model will ultimately enable valve designers to optimise the groove configuration on a sound basis according to given
boundary conditions.
Effects of Temperature on Proportional Valve Dynamics and Reliability
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
H. Hänninen and H. Kauranne and M. Pietola,
2007,
volume 3,
pp. 365-377,
Mai 2007
view abstract
In this article, two proportional pressure control valves are studied in terms of temperature dependencies in their performance and reliability. The valves used in this
study are both directly operated, spool type proportional valves of nominal size 6. These mechanically almost identical valves differ from each other by their electronics. One of
the valves is equipped with traditional analogical electronics and the other with digital electronics. Both of the valves can be controlled with analogical signals and in addition
the one with digital electronics can be controlled, set up and monitored with dedicated software via CAN interface. The valves are tested under different ambient temperatures and results from measurements are analyzed. In addition to finding out their behavior in high temperatures the results of these tests were hoped to show some pre fault indicator for the valves.
Both of the valves were found to exhibit negligible change in dynamics under thermal load. They were also found to be extremely reliable even in high temperatures: neither
of the valves was permanently damaged during the tests. Even though the highest test temperatures were higher than in the real system, the duration of the tests however was
relatively short compared to the time span in which the valves have been found to break.
This means that the mechanism that leads to failure is most likely not so dependant of maximum temperature than long exposures to relatively high temperatures.
Effects of the Variation of Torque Motor Parameters on Servovalve Performance
D. Gordić and M. Babić and N. Jovičić amd D. Milovanović,
In Strojniški vestnik - Journal of Mechanical Engineering,
2008,
volume 54,
pp. 866-873,
Dezember 2008
view abstract
An electrohydraulic servovalve is an essential item of fluid power servomechanism where fast
response, high power output and working fidelity are necessary. Based on detailed and experimentally
verified mathematical model of two-stage spool position mechanical feedback electrohydraulic
servovalves sensitivity analysis has been performed. The effects of variation of few torque motor
electromagnetic parameters (air-gap length (thickness) at null, residual magnetic flux density (magnetic
inductivity) of permanent magnet and number of turns of each coil) on dynamic performance of
B.31.210.12.1000.U2V PPT servovalve have been studied. Obtained results are in accordance with
servovalve engineering design practice.
Efficiency Analysis of a Digital Pump/Motor as Compared to a Valve Plate Design
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
K. J. Merrill and M. A. Holland and J. H. Lumkes Jr.,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 313-324,
März 2010
view abstract
One advantage of hydraulic pump/motors is that they can transmit large amounts of power with respect to their size and weight. An increase in pump/motor efficiency will increase the efficiency of the whole hydraulic system. Current variable displacement pump/motors are very efficient, greater than 90 %, at maximum displacement. However, when at 20 % displacement the efficiency drops drastically to 60-80 %.This work investigates replacing the valve plate in a variable displacement pump/motor with highspeed, actively controlled on/off valves. Due to recent research, high speed actively controlled on/off valves have become an enabling technology. Removing the valve plate eliminates the friction and leakage losses at the valve plate and cylinder barrel interface. Decoupling the pump/motor porting allows each piston to operate independent of the others. One advantage is a decrease in the losses due to leakage at high pressures. A simulation study of the efficiency of both pump types is performed showing the advantages of a digital pump/motor. More efficient pump/motors would have an enormous impact on the industries that need an efficient and reliable power transmission system with high power density.
Efficiency Improvement of Fluid Power Components Focusing on Tribological Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
H. Murrenhoff and C. Enekes and S. Gels and O. Heipl and L. Leonhard and J. Schumacher and A. Wohlers,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 215-248,
März 2010
view abstract
The paper provides an overview of methods to increase the efficiency of hydraulic components with a special focus on axial-piston machines. For this reason it is necessary to focus on tribological systems where parts slide on each other separated by a hydraulic fluid. Losses in these systems are addressed by looking at micro- and macrogeometry. The first ones are microstructures in the material surfaces and an example of the latter is a contoured piston or bore. Between those sliding surfaces the fluid needs to be addressed and some recent research results will highlight current developments of environmentally friendly fluids. Finally, the paper will also address hard-soft tribological contacts given by an elastomer seal sliding against a metal counterpart. Here the simulation approach incorporating a new contact model is treated and some results are introduced.
Efficiency Measurement and Modeling - Essential for Optimizing Hydrostatic Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
R. Rahmfeld and E. Skirde,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 53-66,
März 2010
view abstract
In the mobile machine market it becomes obvious that energy efficiency and fuel consumption are getting more and more important, also as a main sales argument according to hydraulic components and systems. This trend will for sure grow strongly with unavoidable increasing fuel costs in the future. Legislations like TIER4 are accelerating this change in the development and design of mobile machines. This paper describes the fundamentals of efficiency measurement and loss modeling of hydrostatic units, which are the main loss sources in hydraulic drivelines. It is shown that the way from the measurement until a calculation or simulation result according to performance and fuel consumption is complex and offers many traps, what may lead to faulty comparisons and conclusions. Only a precise measurement in combination with a reliable modeling will lead to a useful database for designing hydrostatic systems in a competitive market. Finally, some results are presented, which prove that the efficiency advantage and loss difference can be quite high, depending on the design of the unit. Furthermore, resulting efficiency maps of state-of-the-art wide angle bent axis units used in high efficient power split drives will be depicted – these characteristics show a clear advantage compared to electric motors with power electronics suitable for this type of application.
EFFICIENCY OF UV-IRRADIATION AND FILTRATION IN CONTROLLING MICROBIAL GROWTH IN WATER HYDRAULIC SYSTEMS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
S. M. Soini and K. T. Koskinen and M.J. Vilenius and J. A. Puhakka,
2002, Juli 2002
view abstract
Water hydraulic systems use water as a pressure medium and, thus, do not pose such adverse
environmental impacts as oil hydraulics. Microbial deterioration of the pressure medium and biofouling
of the surfaces restrict the applicability of the technology. UV-irradiation and filtration were used to
control microbial growth in a pilot-scale water hydraulic system. The UV-irradiation (25 mWs/cm2) of
the pressure medium reduced the viable counts of bacteria by 1-2 log10 cfu/ml, whereas the total cell
numbers and the surface attached cell densities remained unaffected. Prefiltration of the pressure
medium (1.2μm, absolute) decreased the total cell number in the water phase by 15% and retarded the
attachment of bacteria. The filtration during the operation (2μm, absolute) decreased the total and the
viable cell numbers in the pressure medium and the cell densities on the surfaces by 52, 28 and 17%,
respectively. Microbial attachment was not prevented by filtration. The microbial water quality
obtained by pre- and on-line filtration of the pressure medium was sufficient to ensure the long-term
operation of the water hydraulic system taken that clean work practises are complied with in assembly
and during the operation.
Efficiency Optimisation of Tracked Vehicles Using Secondary Control in a Single-Circuit Load Sensing System
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
P. Dengler and L. Völker and W. Kauß and M. Geimer,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 115-126,
März 2010
view abstract
The paper describes a concept of a secondary controlled traction drive integrated in a common Load Sensing system. When used in a single circuit system, a secondary controlled drive for tracked vehicles shows a big efficiency optimisation potential compared to other drives. The high losses at turns can be avoided if two secondary controlled units are connected to a single Load Sensing valve. The traction drive is still supplied in a traditional way using Load Sensing. For steering, the secondary controlled units are integrated in a control loop where the steering ratio is used as command value.
Efficiency study of an excavator hydraulic system based on displacement-controlled actuators
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
C. Williamson and J. Zimmerman and M. Ivantysynova,
2008,
pp. 291-307,
September 2008
view abstract
One proposed solution for improving the energy efficiency of mobile hydraulic machinery is displacement controlled actuation, in which cylinders and motors are controlled hydrostatically via variable displacement pumps. This paper compares pump displacement control to traditional load-sensing valve control for a mini-excavator application. Detailed dynamic models of the excavator with both hydraulic systems were constructed, and a trench digging cycle was simulated. The displacement controlled excavator consumed 39% less total energy than the LS excavator for the simulated operation. In this study, the efficiency improvement was almost entirely due to the elimination of valve metering losses rather than energy recovery.
EFFICIENT COLLABORATIVE MODELLING AND SIMULATION WITH APPLICATION TO WHEEL LOADER DESIGN
J. Larsson and P. Krus and J.-O. Palmberg,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 5-13,
November 2004
view abstract
Technical systems are becoming increasingly integrated, partly because of the intensive use of software due to demands
for energy efficiency, performance and customizability. This leads to complicated interactions among the subsystems
during operation. The dynamic behaviour of such a system is hard to predict since every sub-system needs to
be taken into account. Also, the sub-systems often differ in characteristics between engineering domains, and engineers
therefore need to collaborate to make the prediction. A validated model is needed to predict how a change to a system
will affect its behaviour. The paper investigates how the modelling, simulation and validation processes can be organized
in the described case where several engineers from different disciplines are involved. The application studied is a
wheel loader that is complex and represents a large family of machines. In the resulting approach, teams of engineers
from the different disciplines create one general-purpose model, each team using the most appropriate modelling environment.
The system simulation is realized through coupled simulation, where accurate results are achieved by connecting
the simulation environments by so-called bilateral delay lines.
Efficient Hydraulics in Mobile Machines - Very Competitive Technologies
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
Eckhard Skirde,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 23-35,
März 2010
view abstract
The paper is intended to provide an overview about hydraulics for Mobile machines, with emphasis on efficiency and power losses. It is shown that improvements have been made with recent developments and there is still room for improvement with new concepts in development, one of those being presented here. Emphasis is put on component as well as on system solutions. Electric drives will have to provide similar performance to be competitive from technical aspects, given that Reliability and Durability in harsh operating environment can be proven.
Efficient Methods for Numerical Modeling of Laminar Friction in Fluid Lines
D. Nigel Johnston,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 829-834,
Dezember 2006
view abstract
An improved method for simulating frequency-dependent friction in laminar pipe flow using the method of characteristics is proposed. It has a higher computational efficiency than previous methods while retaining a high accuracy. By lumping the frequency-dependent friction at the ends of the pipeline, the computational efficiency can be improved further, at the expense of a slight reduction in accuracy. The technique is also applied to the transmission line method and found to give a significant improvement in accuracy over previous methods, while retaining a very high computational efficiency.
Efficient Regeneration
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
H. Kolvenbach,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 153-164,
März 2010
view abstract
The majority of industrial motion is linear motion, either provided by electromechanical drives or hydraulic differential cylinders, depending on the force density required. This paper deals with the intelligent integration of system’s functionality into hydraulic directional control valves to make them competitive to or even better than electromechanical drives with regards to controllability and energy consumption. Contrasting arrangements of regenerative circuits are discussed and energy saving potentials are described.
Efficient, Safe and Reliable Recuperation: Regenerative Accumulator in Honeycomb Receiver
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
A. Stroganov and L. Sheshin,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 177-187,
März 2010
view abstract
The paper presents new solution for a fluid power storage device with reduced thermal losses and improved safety and configurability. Presented compressible metal regenerator embedded into accumulator provides nearly isothermal character of gas compression and expansion. This increases accumulator efficiency at various operational modes including long storage. Presented honeycomb receiver designed as the accumulator shell reduces by several orders of magnitude the potential gas energy, which can be released at the storage device damage. A hydraulic test rig for the measurement of energy recuperation efficiency is described and shown in the pictures. The visualized results of computer safety factor analysis for partly damaged storage device are presented in the pictures. Presented experimental data demonstrate a noticeable increase of the energy recuperation efficiency in all tested regimes. Computer evaluation corroborates substantial danger reduction when using honeycomb receiver as accumulator shell.
Elastic Beams with Identical Buckling and Vibration Mode Shape
M. Garstenauer and R. Scheidl,
In Zeitschrift für Angewandte Mathematik und Mechanik (ZAMM),
1998,
volume 79,
pp. 341-342,
August 1998
view abstract
In this paper we discuss the problem of determining the shape of simply supported beams with added masses to achieve identical buckling and vibration mode shapes. Motivation for this work stems from the design of a new type of hydraulic switching valve utilizing a parametrically excited beam as actuation element. An analytical expression for the necessary thickness of the beam is developed, ths shape of the buckling mode and the eigenvalues (i.e. buckling force and vibration frequency) are determined by solving a Sturm-Liouville Eigenvalue Problem numerically.
Electric hydrostatic drive – a concept for the clamping unit of a high-speed injection moulding machine
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
S. Räcklebe and S. Helduser,
2007,
pp. 245-254,
September 2007
view abstract
The paper deals with modelling, simulation and performance improvements of an electric hydrostatic driven clamping unit of a high-speed injection moulding machine. Main objective is to demonstrate the use of coupled simulation in the development of drive systems. Special attention is given to the modelling of components and subsystems of the hydrostatic drive concept but also on energy efficiency. Simulation results are validated by measurements.
ELECTROHYDRAULIC CONTROLLER AS A HYDROTRONIC ELEMENT OF DRIVING SYSTEM
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
H. Chrostowski and K. Kędzia,
2006,
volume 2,
pp. 523-532,
Juni 2006
view abstract
In the article there have been presented the tasks executed in a driving system by an electrohydraulic controller of a
hydrostatic unit. For a given mathematical model of a selected controller the simulation research has been conducted
defining its dynamic characteristic. The examples of result from optimisation research of hydrostatic driving system,
consisting of hydrostatic transmission, hydropneumatic accumulator and IC Engine as a primary source of energy have
been presented.
Electro-hydraulic Control System of Shield Tunnel Boring Machine for Simulator Stand
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Guoliang and G. Guofang and Y. Huayong and X. Tong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 94-99,
April 2005
view abstract
Aimed at the design requirements of shield tunnel boring machine (hereinafter refer to as shield) for simulator stand, electro-hydraulic control systems of shield were designed and manufactured by applying electro-hydraulic proportional control technology, which included thrust electro-hydraulic control system, screw conveyor electro-hydraulic control system and cutting wheel drive electro-hydraulic control system. Experimental analysis was also carried out. The experimental results showed that the designed electro-hydraulic control systems could meet the tunnelling requirements in ail kinds of geological conditions. The earth pressures could also be controlled in the range of set value by adjusting the thrust speed, screw conveyor revolving speed and cutting wheel revolving speed, which led to reduce ground deformation.
Electro-Hydraulic Dual-Circuit System to Improve the Energy Efficiency of Mobile Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
R. Finzel and S. Helduser and D.-S. Jang,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 151-163,
März 2010
view abstract
This paper deals with the enlargement of a one-pump electro-hydraulic control system in to a flexible dualcircuit system to increase the energy efficiency reducing the throttle losses on the valves to the lower loaded actuators. They combine the advantages of a valve control system regarding the machine space, the dynamic and the flexibility with the advantages of the pump-controlled system regarding the minimized throttle losses. The dynamic and steady state response of the new system have been investigated by means of measurements and simulations. The energy consumption of an excavator can be reduced by about 30% in comparison to a state of the art hydraulic-mechanical one-pump-Load-Sensing system.
Electrohydraulic Fully Flexible Valve Actuation System With Internal Feedback
Zongxuan Sun,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
März 2009
view abstract
Fully flexible valve actuation (FFVA) system, often referred to as camless valvetrain, employs electronically controlled actuators in place of the camshaft to drive the intake or exhaust valves for internal combustion engines (ICEs). This system offers significant fuel economy benefits, emissions reduction, and better torque output performance for the ICE. It could also enable a number of advanced combustion concepts, such as homogeneous charge compression ignition. It further provides a common platform that incorporates the functions of cam phasing, two/three step cam or continuously variable lift, cylinder deactivation, port deactivation, etc. Therefore it is desirable to develop FFVA systems for future engines. In this paper, we first outline the technical barriers for developing production-viable FFVA systems. To address those challenges, a new electrohydraulic valve actuation concept with the “internal feedback” mechanism is presented. Key technical issues, such as dynamic range capability, valve motion performance, and energy consumption, are analyzed. Experimental results based on a prototype system are shown to demonstrate the capabilities and performance of the proposed system.
Electro-Hydraulics of the Stage Tables of the Lower Theater Scene (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
P. Jasiok and R. Rojek,
2008,
pp. 105-111,
September 2008
view abstract
Small built-up dimensions with big performance, precision of positioning and synchronization and limitation of acoustic emissions, these are the main advantages of electro-hydraulic systems of the tables of main stage of the lower scene of the Chamber Theater in Martin.
3D-design of the table with electro-hydraulics is shown at the picture. Control of separate hydraulic cylinders that are situated in the space of lifted tables is realized by means of the control units that are furnished with the applicable control and regulation elements, where the actuating element is one-rate regulating valve. These control units are placed also in the room of lifted tables approximately in the half of the table. They are connected with hydraulic cylinders with rigid piping distribution and pressure hoses.
Two double-acting hydraulic cylinders 125/90 –2450 that are controlled with control units assure hoisting for each table. Electro-hydraulic system with SYB 2000 – control system Bosch Rexroth is solved in a way that makes possible a synchronous run of 2-axis (i.e. 2 HC) and a precise set-up on chosen position by reading the table position by a couple of the absolute encoder units with interface SSI ( always one for 1 HC).
Control system assures also the group regulated control of 4 tables in parallel run.
In functional and playing or entrance positions the table is arrested with four linear electric drives.
Hydraulic circuits are solved as open with a source of constant pressure. Main hydraulic circuit is made of not regulating pumps with the possibility to set up pressure on safety valves and the accumulator station 280 dm3 with pressure range 12-15 MPa and charged with the pumps of the drive units. The auxiliary hydraulic circuit consists of the sliding-vane pump with constant flow rate for circulating tank filtration.
The pumps are mounted on a joint frame, and suction from 2000 liter tank is solved for each pump separately. On the outlet they are furnished with pressure, remote control proportional valves that enable start-up of electric motors in pressure-free mode. Input for three electric motors is 3x37kW.
During putting into operation there were verified all the project parameters, the scenic states and the system safety in accordance with the risks analysis including control system SYB 2000 that shows the safety category SIL3 –according to ČSN EN 61508.
The certification has been performed by the Technical Inspection of the Slovak Republic according to the by-law 718/2002 SR.
Electro-hydraulic Technique Based Obstacle-avoidance System of Multi-DOF Complicated Mechanical Arms
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Baihai and Z. Dapeng and Y. Zhanwu and X. Tibing,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 763-766,
April 2005
view abstract
Ultrasonic sensors and infrared ray sensors are combined to detect obstacles and measure the information between arms and obstacles. A position/velocity self-adaptation fuzzy controller is designed to realize obstacle-avoidance control. The electro-hydraulic proportional technique is used to realize arms' prompt and exact movement at one speed of three kinds which are full speed, fast speed and slow speed.
ELECTRONICALLY CONTROLLED HYDRAULIC BUCKET STABILIZER FOR MOBILE MACHINE
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
J. Uusisalo and J. Vilenius and O. Karhu and M. Hyvönen and K. Huhtala,
2006,
volume 2,
pp. 357-367,
Juni 2006
view abstract
A small general-purpose teleoperated hydraulic mobile machine has been studied at Institute of Hydraulics and
Automation at Tampere University of Technology since 2001. One goal of the research work is to produce autonomous
operations to help the operator to control the machine and so eventually develop fully autonomous machine.
Electronically controlled automatic hydraulic bucket stabilizer is part of that research work.
The angle of the bucket is measured by means of inclinometer. Control algorithms are carried out with a digital signal
processor. The bucket of the machine is controlled a typical proportional valve, which is designed for mobile purpose.
Characteristics of the valve, which are critical in this application, are discovered. Main structures of the mechanics,
hydraulics, and electronics are introduced.
A verified simulation model is created to help understanding behaviour of the system and also to improve control
algorithms. Implementation of different types of control algorithms, e.g. P-control and feedforward control are
introduced. Simulated results of introduced control algorithms shown. Also, some discovered characteristics of the
valve and spools are enclosed.
Electronically Controlled Hydrostatic Travel Drive of Rubber - Tyred Roller (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
M. Obert,
2006,
pp. 207-217,
Mai 2006
view abstract
The described machine with Rexroth electronics is a new generation of a rubber-tyred
roller with the high comfort for an operator, with up-to-date design, with the “1 x 1 m” visibility
from the operator’s place and with wide range of user adaptation of operation weight. It is
designed for mid and large scale compaction of asphalt or loose and semi-cohesive materials.
The machine is based on a rigid frame with 4 + 4 smooth rubber tired wheels, steerable front
axle and driven rear axle. The machine is equipped with Cummins engine and with the
hydrostatic drive system from Bosch Rexroth. The hydrostatic travel drive and steering system
consists of following parts:
• hydraulic pump A4VG 125EP
• hydraulic motors A6VE80EP
• planetary gearboxes GFT 26T2
• control unit RC 6-9
• steering valve SP08
• angle sensor WS1
• revolution sensor HDD
The drive system is controlled with the Rexroth electronic control unit type RC6-9 which allows
to modify software and reach more „machines“, it means the same machine with different
features based on the customer requirement. Pressure sensor, revolution sensors and angle
sensors create a feed back system which is very important for safe operation of the machine.
The other advantage of the electronic is diagnostic and error analysis by service tool
BODEM. This way handled machine fulfils the requirements of pollutants emission directives and
other customer specific requirements.
Electronic Flow Control Valve (EFCV) with Pressure Compensation Capability
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
Q. Yuan and C. Schottler and J. Y. Lew,
2007,
volume 2,
pp. 179-192,
Mai 2007
view abstract
A new concept for an Electronic Flow Control Valve (EFCV) with pressure compensation capability is introduced. Based on its embedded sensors and micro controller, the EFCV can provide flow control without the need of load/displacement/speed information from the power elements, like hydraulic cylinders
or hydraulic motors. The flow controller inside the EFCV approximates the actual flow rate by the quasi-steady flow rate equation. Experimental studies show that the analytical model is not accurate enough to cover all operating conditions. Therefore, an experiment-based calibration method is suggested so that the electronic flow controller can provide accurate flow control across the working pressure and flow range. Finally, an innovative application of the EFCV, a self-sensing cylinder, is also presented.
Electronic Hybrid Limiter (EHL) for Pump Displacement
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
R. Paoluzzi and L. G. Zarotti and M. Ruggeri and C. Fantuzzi,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 25-32,
November 1996
view abstract
The paper reports upon numerical simulation tests carried out on a variable displacement axial piston pump equipped with multiple automatic controls. The swashplate control circuit includes two classical hydraulic stages with two tandem three way valves (the pressure compensator and the flow limiter) and a servovalve with digital control circuit
acting as a hybrid torque or/and speed limiter. The dynamic
response of the system is evaluated for both separate and combined control functions. The effect of changes in the digital control circuit is discussed with reference to the system response to various load demands with special emphasis devoted to the benefits induced by the use of fuzzy control logic.
Electronics in Mobile Hydraulics (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
K. Selucký,
2008,
pp. 245-250,
September 2008
view abstract
Electronics matched to the hydraulics of mobile machines make things so much easier. Rexroth mobile electronics also make it far simpler to optimize hydraulic systems – parameters are all altered on the PC, so there is no need to keep changing oily throttles. The electronics also include lots of useful features. The consistent and configurable modular architecture saves a lot of development time. Perfectly coordinated hardware and software components reduce costs. For example, electronic joystick settings can be varied according to the application. And, just as importantly, electronic eco-modes reduce fuel consumption considerably.
The Rexroth range of mobile electronics includes all the components for a complete drive system from a single source: programmable controllers and amplifiers, application software and system solutions, sensors, input devices and control panels, programming and parameterization tools. Overall solutions combining driving and working functions are optimally tailored to one another. Mobile electronic components meet all the requirements for harsh use in mobile machines. BODAS controllers are the powerful backbone to the BODAS system. On the one hand they receive and process signals from operator panels and sensors. On the other they calculate and generate the output signals to pumps, motors, valves and auxiliary devices. In the BODAS hardware building set, several robust variations of the controllers and one extension module are available. Main benefits of the controller are sealed die cast aluminum housing free from potting compound, from Bosch automotive development, resistant to salt and dirt, watertight housing and connector, high temperature resistance for use in alpine winter or tropical conditions, integral Bosch watchdog for processor monitoring and potentiometer monitoring to prevent broken lines and short-circuit faults and others functions. Inputs are freely definable as analog, digital or frequency input, all outputs can be used simultaneously and independently. High clock frequency up to 40 MHz for time-critical applications is standard as well CAN-Bus interface. The significantly expanded BODAS sensor family as well as joysticks and displays are perfectly harmonized to the controllers and the Rexroth hydraulic components for the entire spectrum of mobile applications. The following list contains a few examples: fun control for buses and trucks, electronic accelerator pedal, electro-hydraulic header height control for combine harvester, electro-hydraulic hitch control in tractors, speed measurement in transmissions, ASR function and others. Monitoring and parameter assignment functions are realized using displays, e.g. color display DI3 with resolution VGA 640 x 480.
BODAS offers complete software packages that you can configure yourself with very little effort. With the help of BODAS tools and the user-friendly documentation, you can start up your machine step by step. Customizing, in other words the adaption of the basic modules is quick and cost effective. BODAS provides the opportunity to program your own solution completely and independently also. With the BODAS-design graphical programming interface you can develop, simulate and debug your program on a PC and then transfer it onto the controller. The programming interface is based on the standard IEC 6 1131-3 and is comparable to industrial control systems such as PLC. Programming is made easier with BODAS software modules from the software library. And the whole process is carried out in a modern, user-friendly Windows interface.
Electropneumatic Test Bench for Aeronautics Application: Robust Control
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
A. Girin and X. Brun and F. Plestan,
2007,
volume 2,
pp. 249-260,
Mai 2007
view abstract
This paper presents design, modelization and control of an electropneumatic test bench. The test bench was writing for aeronautic application. The model of system is extremely nonlinear, so a nonlinear control based on sliding mode theory is
synthesis and compare with scheduling feedback. Interest of higher order sliding mode controller is the finite time convergence and its robustness with respect to uncertainties and parameters variations.
Enabling Autonomous Functions on Hydraulic Excavator Attachment
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
O. Karhu and J. Moya and J. Uusisalo and K. Huhtala,
2007,
volume 2,
pp. 35-45,
Mai 2007
view abstract
Hydraulic mobile machines are used in various tasks. Many of these are repetitive and boring or even dangerous for human operator. Therefore it would be very convenient if the mobile machine could perform some tasks autonomously. In this work autonomous excavation is discussed. Required control electronics, sensors, and algorithms are studied. Special requirements due to demanding operating conditions and different soil types are considered. An excavator attachment for a hydraulic mobile machine is used to test the ideas. The control system is installed and software is designed. The system is tested. The test system and results are presented and discussed.
End Effectors in the Automation Industries under Energetic Aspects - A Holistic Approach
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
F. Simons and M. Haag,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 271-277,
März 2010
view abstract
Everyone is requested to save energy; also it is practically combined to CO2 emission. For industries all over the world beside the environmental protection it becomes more and more a question of competitiveness. The degree of effectiveness to transform electric energy to pneumatic energy is low, but to a high extend given physically. Automation is advised to deal with that matter intensively, due to the fact that just a global replacement of pneumatics to mechatronics is senseless and technologically just wrong. More and more clients, and to add increasingly, the legislation challenges a serious discussion and strategies have to be developed for saving pneumatic cost apart from just searching leakage (it is estimated that about 20% is lost in pneumatic systems). SCHUNK has defined a holistic approach in a chain from development to production and its operation in an automation of pneumatic components solution.
ENERGY CONSUMPTION ANALYSIS OF AN INNOVATION VVVF CONTROLLED HYDRAULIC ELEVATOR
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
B. Zhang and B. Xu and H. Yang,
2006,
volume 1,
pp. 53-64,
Juni 2006
view abstract
Nowadays, the disadvantages of hydraulic elevator, such as low efficiency and high energy consumption, limit its
application. Therefore, the key interest of hydraulic elevator is aimed at the reduction of energy consumption and
realization of high efficiency. Considering energy-saving and environmental protection, a new VVVF controlled
hydraulic elevator with closed circuits is proposed. A four quadrants drive unit, which can operate both as pump and
motor, is applied in this system. It can drive load when the hydraulic elevator car is fully loaded and recover extra
energy on the contrary condition. The recovered energy is stored in accumulator and can be reused to power load in
the following work cycle, so the total energy consumption is reduced and the system’s efficiency is increased. The
structure of this system is fully expressed in this paper.
Energy consumption characteristic of this system is discussed in detail through theory analyses and experiments
investigate. The energy loss condition is revealed and the system efficiency is showed from the measurement data. There
is also a comparison between several classic hydraulic elevators, including valve controlled system, conventional
VVVF controlled system, an improved VVVF system and the system mentioned above. And the results show the
advantages of this new designed system obviously.
Energy Consumption of the Hydraulic Circuit of a Mid-Size Power Tractor
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Borghi, Massimo and Zardin, Barbara and Mancarella, Francesco and Specchia, Emiliano,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 37-50,
März 2010
view abstract
This work focuses on the hydraulic circuit that feeds the remote actuators of a mid-size power agricultural tractor. First of all, the energy consumption of a traditional load sensing architecture, which uses a single electronically controlled spool valve, is analyzed. For this kind of circuit, the position of the spool generally determines, at the same time, pressure drops both at the inlet and at the outlet section. The consequence is that in the majority of the situations both the meter-in and the meter-out configuration is not optimized in terms of energy consumption. An alternative architecture, with an independent metering configuration, based on a pressure based control strategy is analyzed and modelled. Energy consumption comparisons of the two systems are made, using different duty cycles, involving resistant and overrunning loads.
Energy Dissipation Of The Hydraulic Circuit Of Remote Auxiliary Utilities Of An Agricultural Tractor
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Borghi, Massimo and Mancarella, Francesco and Zardin, Barbara,
2010,
pp. 563-577,
September 2010
view abstract
The aim of this work is to analyze the energy dissipation related to the hydraulic circuit which controls the remote auxiliary utilities of an agricultural tractor. This circuit is a typical hydraulic load sensing multi actuators system. This kind of system provides a good control strategy but it is characterized by quite high energy dissipation, especially when several actuators are working together under different variable loads. In this paper, the traditional load sensing system is modelled using a lumped parameter approach, and the
energy dissipations are evaluated with reference to an actual duty measured on an agricultural tractor. Then, an alternative and more energy saving circuit architecture is
introduced, based on an independent metering concept: in this architecture the single spool auxiliary valve is substituted with two electronically controlled proportional valves. The
system has been also equipped with an electronically controlled variable pump; two strategies to control both the pump and the proportional valves are introduced. The energetic analysis is performed also for the alternative architecture using the same duty cycle, with the aim to identify the advantages, disadvantages and the critical features of this system with respect to the original one. Significant energy saving percentage characterizes
the independent metering architecture, which seems to be a promising alternative to the standard hydraulic load sensing system.
Energy Efficiency Analysis in Pneumatic Plants for Food Processing
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
D. Bottazzi and M. Milani and L. Montorsi,
2010,
volume 2,
pp. 435-450,
Juni 2010
view abstract
This paper focuses on the numerical analysis of pneumatic systems for food processing, in particular for coffee roasting
plants, and it evaluates the energy requirement for batch coffee roasting process. The analysis is performed using a
multi-phase multi-component approach, properly tailored to address the phenomena that are influencing the overall
behavior of complex plants.
First, a lumped and distributed numerical model is used to simulate the pneumatic behavior of a reference plant, which
uses an exhaust gas recirculation technique to improve the system efficiency. Among others, the theoretical models
implemented to detail pipe – ambient heat transfer and thermal sources or sinks, as well as the combustion chamber
behavior or the coffee heating and roasting are presented. Afterward, predicted temperature, pressure and mass flow
rate are compared with experimental measurements (obtained on a real pneumatic plant) to set the reliability and
accuracy of the numerical approach.
Finally, the multi-phase multi-component approach is applied to the analysis of different architectures of coffee
roasting plants, in order to define the influence of the pneumatic layout on the system efficiency.
In particular, the recirculation plant behavior is compared to open cycle scheme and, for both layouts, the effects of
heat recovery from exhaust gases are also evaluated.
ENERGY EFFICIENCY OF HYDRAULIC SYSTEMS WITH HYDRAULIC CYLINDER UNDER PROPORTIONAL CONTROL
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
D. Piatek,
2006,
volume 1,
pp. 41-51,
Juni 2006
view abstract
There are two common opinions about energy behavior of hydraulic systems. The first one is low energy efficiency of
hydraulic system with series throttling and the second one is high efficiency of hydraulic linear motor – hydraulic
cylinder. The results of theoretical and laboratory researches on both opinions are presented in this paper.
Energy Efficiency of Mobile Working Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
S. Sgro and M. Inderelst and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 201-212,
März 2010
view abstract
Decreasing energy resources as well as increasing fuel costs and stricter CO2-regulations are forcing engineers to research energy saving concepts for mobile working machines. Therefore it is not only necessary to optimise the drive train of these machines, but also to improve the working hydraulics with techniques for energy saving and recuperation. A comparatively easy possibility of meeting the named criteria is controlling and supplying hydraulic actuators by hydraulic transformers. This paper deals with the possibility of controlling the working hydraulics of an excavator by using hydraulic transformers and their energy saving potential. Within a simulative research the linear drives, i.e. the two boom cylinders, the arm cylinder and the bucket cylinder, are controlled by hydraulic transformers.
Energy Efficient Control of Multiactuator Digital Hydraulic Mobile Machine
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Huova, Mikko and Karvonen, Matti and Ahola, Ville and Linjama, Matti and Vilenius, Matti,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 25-36,
März 2010
view abstract
The energy efficiency of load sensing working hydraulics of mobile machines should be improved. Digital hydraulics is one approach to decrease the losses of cylinder drives and this
study concentrates on the design of the control mode selection algorithm for multiactuator system. Measurements are done on a 5-ton wheel loader and the energy consumption of a digital valve system is compared to a traditional load sensing system using simulations.
Energy-Efficient Design and Dimensioning of Rolling Bearing Supports in Gearboxes
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
O. Koch and C. Seeberger,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 301-312,
März 2010
view abstract
It is becoming more important to dimension machine elements correctly due to increasing energy costs and the current CO2 debate. This also applies to rolling bearings because they are used almost everywhere and affect the efficiency of machines. The energy efficiency of assemblies can be increased by designing rolling bearing supports correctly.
Schaeffler KG has developed a calculation tool, BEARINX ®, which can be used to calculate the overall bearing power loss of a gearbox and can trace the power loss back to individual bearing positions. This program enables the selection of bearings that are matched to the application, and means that overdimensioning can be avoided. A large number of influences are taken into consideration in the calculation, for example, lubrication, bearing friction and shaft tilting. As an example, an analysis is conducted on a gearbox that achieves higher efficiency due to an intelligent combination of hydrostatics. The bearing locations were designed with BEARINX ®.
Energy Efficient Switching Control by a Hydraulic Resonance Converter
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 1999
R. Scheidl and G. Riha,
1999,
pp. 267-280,
September 1999
view abstract
A so called hydraulic resonance converter which enables the energy efficient switching control of hydraulic drives is presented. The performance characteristics, the role of the main design parameters and basic dimensioning rules are given, based on mathematical models and on experiments performed with a prototype. It is shown that for reasonable practical realisations high speed switching valves are needed.
Energy Losses in Piston Type Hydraulic Accumulator
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
J. Juhala and H. Kauranne and M. Pietola,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 177-188,
März 2010
view abstract
Typical hydraulic systems produce some main action like movement or lifting of a load. These operations usually offer a possibility to recover at least a part of the energy in counteraction. The recovered energy can be stored in various ways, but since every energy conversion induces losses, the number of these should be minimized. Therefore a pressure accumulator seems to be ideal storage component; however, they also have some disadvantages such as energy losses in form of heat transfer. The aim of this study is to validate the simulation model of an accumulator and to study the ability of different thermal insulation solutions to enhance the energy efficiency of the accumulator. The results of this study consist of simulations and experimental measurements. The results showed that the model of accumulator is accurate enough for regeneration simulations and that energy efficiency of accumulator can be improved using thermal insulation.
Energy Management Strategy For a Hydraulic Hybrid Vehicle using Stochastic Dynamic Programming
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
J. J. Meyer and K. A. Stelson and A. G. Alleyne and T. O. Deppen,
2010,
volume 1,
pp. 59-68,
Juni 2010
view abstract
Hydraulic hybrid vehicles can save fuel while maintaining performance due to the high power density of hydraulics.
This paper investigates the best way to control a parallel hydraulic hybrid passenger vehicle to minimize fuel
consumption while maintaining performance by using stochastic dynamic programming. A variety of drive cycles are
used to form a Markov chain with velocity and acceleration as the states. A transition probability matrix is calculated
to determine the probability of being in a future state given the current state. Using these statistics, stochastic dynamic
programming develops a control law that can be implemented in real time without requiring exact knowledge of the
drive cycle. The results show that stochastic dynamic programming increases fuel economy for two drive cycles.
Energy Optimal Open Loop Control of Standard Pneumatic Cylinders
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
M. Doll and O. Sawodny,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 259-270,
März 2010
view abstract
The article proposes an energy optimal open loop control of a special valve connection structure. The valve connection structure includes a by-pass valve to recycle compressed air between the chambers of a cylinder. An open loop energy optimal control strategy is developed with which the energy efficiency of standard on/off controlled pneumatic actuators is increased. The optimisation is done with a genetic algorithm including various constraints and cost functions. It is tested with several constraints used in some scenarios, is validated by measurements and compared to standard pneumatic systems working with exhaust flow control valves.
Energy recovery of hydraulic elevator using accumulator
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
H. Yang and B. Xu and W. Sun and J. Lin,
2006,
pp. 45-64,
September 2006
view abstract
In the conventional valve controlled hydraulic elevator, by-pass throttle is commonly used to control the cabin speed. In this system design, when the cabin moves downwards, the entire potential energy of cabin is wasted and converted into fluid heat by throttling. This is why the energy consumption of a hydraulic elevator is much higher compared to that of the traction elevator. In this paper, some different methods of energy recovery using hydraulic accumulator have been introduced and discussed in detail. Experimental studies on energy-saving have been carried out to compare the energy consumption of different system designs of hydraulic elevator.
Energy Recovery Systems in Small Scale Reverse Osmosis Seawater Desalination Plants
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
W. Parker,
2004,
pp. 425-432,
Juni 2004
view abstract
The majority of the earth’s water is salt water and can be found in the oceans. However, less than three
percent is fresh and most is locked up in glaciers and polar ice caps and is therefore unrecoverable for the
6 thousand million users on the planet. The need for hydrological resources for urban, agricultural and
industrial use is an increasing problem on a world level. For some countries and applications desalination is
the only realistic and practical hydrological solution. For example, the installation of small reverse osmosis
desalination plants on boats, hotels and housing estates could solve the problem of drinking water in tourist
areas. Unfortunately, desalination is a costly process due to the fact that the price per litre of fresh drinking
water is a direct function of the energy needed to carry out the process. This paper aims to give an over
view of a thesis dedicated to reducing this cost by incorporating energy recovery systems into the process.
ENERGY RECUPERATION IN HYDROSTATIC TRANSMISSION SYSTEM
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Kucybała and J. Pobędza,
2008,
pp. 489-492,
Juli 2008
view abstract
The objective of this research is to elaborate simulation model of hydrostatic transmission with energy recuperation
system of fork lift. Mathematical model of the system consists of motion and flow continuity equations as well as
formulas determining hydro-pneumatic piston accumulator behaviour. In accumulator model heat transfer phenomena
was included and Van der Waals real gas low, to calculate gas parameters during its operation. Exemplary simulation
results illustrate hydrostatic transmission system operation for both cases: with energy recuperation and without, what
allow determining possible energy saving.
Energy recuperation in working hydraulics of excavators
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Inderelst and S. Sgro and H. Murrenhoff,
2010,
pp. 551-562,
September 2010
view abstract
Decreasing fuel resources as well as increasing energy costs and stricter CO2 regulations force engineers to research energy saving concepts for mobile working machines, especially for earth-moving machines like excavators. The optimisation of these machines is not only focused onto the drive train. Also, the supplementation of the working hydraulics by techniques for energy saving and recuperation is becoming more and more important. A comparatively easy possibility to meet the named criteria is controlling the hydraulic actuators of an excavator using hydraulic transformers.
Compared to a conventional load-sensing system which deals as the reference system in this study, a hydraulic control system using hydraulic transformers is introduced. After an explanation of both systems, they are analysed by means of hydraulic system simulations.
The energy consumption and losses are visualised by using Sankey Diagrams. Because throttling losses over control valves can be avoided in the transformer-controlled system and potential and kinetic energy can be recuperated easily, it is pointed out that the new system approach is more efficient. Simulated by using the same load and stroke cycles and modelled by the same level of detail, the energy consumption can be reduced by up to 70% of the reference system, using a hydraulic transformer controlled system in an excavator.
Energy Regenerative Actuator for Motion Control With Application to Fluid Power Systems
Donald Margolis,
In Journal of Dynamic Systems, Measurement, and Control,
2005,
volume 127,
pp. 33-40,
März 2005
view abstract
Motion control is principally involved with moving a load along some prescribed trajectory. Flight simulators and numerically controlled machine tools are examples where motion control is required. Actuators for motion control are typically electrohydraulic, electropneumatic, or electromechanical. An electric signal from a controller modulates high-power elements that control motion of a load in some prescribed manner. Since loads are continuously being accelerated and decelerated, actuators absorb energy as frequently as they output energy, but power is required from the supply regardless of the direction of power flow in the actuator. The absorbed power is simply dissipated in the actuator or power supply. An actuator concept is developed here in which energy storage elements become part of the actuator, and absorbed power is recovered while still performing a high level of motion control. The concept is developed for a fluid power application, but is not restricted to fluid-type devices. Practical realizations of this concept will allow downsizing of power supplies as well as reduced power consumption for any particular application.
Energy Saving by Use of an Active Coutnerweight System for Medium Size Excavators
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
A. Gawlik and S. Michalowski,
2010,
volume 2,
pp. 733-740,
Juni 2010
view abstract
Paper describes the concept of kinematic structure and hydraulic system of energy saving by utilize of an active
counterweight, for medium size excavators. The hydraulic system of active counterweight is connected with the boom
standard hydraulic system. The counterweight mechanism is homothetic to linkage mechanism of the excavator. The
homothetic transformation applies to kinematics structure and the center of mass positions. The conservation of the
homothetic transformation provides static unloading of boom cylinder by the counterweight cylinder pressure. The aim
of investigations is saving energy for machines which can use movable counterweight to unload the excavator linkages.
Modelling and simulation tests are performed for selected work cycle to determine the key parameters of hydraulic
system, such as: cylinders velocity, working pressure, oil flow etc. Primary simulation results compare power
consumption for standard and modification system during the same work cycle. Presented solution of hydraulic system
does not change functional properties of the excavator.
Energy saving hydraulic actuators for mobile machines
Proc. 1st Bratislavian FLUID POWER symposium
R. Rahmfeld, M. Ivantysynova,
1999,
view abstract
In order to achieve a complex motion control of a multi-link mobile manipulator the use of servo valve
controlled linear hydraulic actuators is one possible way. The use of servo valves for motion control
leads to an excessive dissipation of primary energy. This paper introduces a circuit design for a pump
controlled actuator with differential cylinder for heavy load manipulators. It is pointed out that because
of the smaller servo pumps and other new components in the pump controlled actuators the result of a
substitute of valve controlled actuators through pump controlled actuators in an overall manipulator
system leads to no decrease in component mass and volume.
Key words: pump controlled actuator, mobile machines, heavy load robots and manipulators
ENERGY SAVING HYDRAULIC DISPLACEMENT CONTROLLED LINEAR ACTUATORS IN INDUSTRY APPLICATIONS AND MOBILE MACHINE SYSTEMS
Proc. of LDIA 2003, Birmingham, UK
R. Rahmfeld, M. Ivantysynova,
2003,
view abstract
This paper presents a new displacement con-trolled linear actuator developed for industry applications and mobile machine systems. The basic circuit solution and the developed control concepts are briefly explained. Fur-thermore, the energy savings and other system advantages are discussed. The actuator has been implemented and tested in a construction machine and is now ready for use in a wide area of applications in automotive, transportation and industry.
Key words — Linear Hydraulic Actuator, Displacement Control, Energy Saving, Single Rod Cylinder.
Energy Saving in Pneumatic Servo Control Utilizing Interchamber Cross-Flow
Xiangrong Shen and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 303-310,
Mai 2007
view abstract
This paper proposes a structure and control approach for the energy saving servo control of a pneumatic servo system. The energy saving approach is enabled by supplementing a standard four-way spool valve controlled pneumatic actuator with an additional two-way valve that enables flow between the cylinder chambers. The “crossflow” valve enables recirculation of pressurized air, and thus enables the extraction of stored energy that would otherwise be exhausted to the atmosphere. A control approach is formulated that supplements, to the extent possible, the mass flow required by a sliding mode controller with the recirculated mass flow provided by the crossflow valve. Following the control formulation, experimental results are presented that indicate energy savings of 25–52%, with essentially no compromise in tracking performance relative to the standard sliding mode control approach (i.e., relative to control via a standard four-way spool valve, without the supplemental flow provided by the crossflow valve).
Energy Saving in Pneumatic Systems; Historical Overview and Current Status
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
J. A. Trujillo,
2004,
pp. 559-565,
Juni 2004
view abstract
Energy conservation is currently commonplace in almost all industrial areas. Day by day the target of
reducing the amount of energy required to carry out certain work as well as the cost associated with any
industrial process has become more and more essential. However, historically, the way this matter has
been treated through the years has not always been the same. Measures were taken in order to reduce the
energy consumption in different industrial sectors and researchers were not blind to that subject either.
Investigations, taking into account in some cases the complexity of the analysis of dynamic systems, were
also trying to support directly or indirectly energy conservation activities.
The industrial growth has brought us to a point in which energy conservation is more than a cost reduction
matter. Worldwide environmental conservation has become one of the most important subjects in our
current society. Global warming has an important impact in our everyday lives and unfortunately is a very
serious problem in the world today.
Pneumatics as a form of energy needs to be also analysed in order to contribute to a reduction in energy
consumption.
This paper will present the strategies and solutions proposed in the past on increasing energy savings in
pneumatic systems as well as the future research to be carried out based on the results obtained until now.
Energy-Saving Method of Pneumatic Servo Position Control System Based on Separate Control of Motion Trajectory and Pressure Trajectory
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
Z. Xiaocong and C. Jian and T. Guoliang and Y. Bin,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 329-342,
März 2010
view abstract
The energy-saving control strategy for the pneumatic servo position control system based on separate control of motion trajectory and pressure trajectory are proposed. An adaptive robust pressure controller is designed to keep the pressure level in chamber of cylinder on an even keel when the pneumatic cylinder is moving, which will result in small variation of cylinder’s friction force and facilitate the precise modeling of friction force. An adaptive robust motion controller is designed to achieve high precision position tracking for the rodless pneumatic cylinder with large time-varying friction force. It is guaranteed by means of velocity-approach-position-modification that the direction of friction force is not reversed. The function and choosing method of desired velocity correction term is analyzed. The air consumption of pneumatic servo system based on separate control of motion trajectory and pressure trajectory is obtained and a new approach to computing air consumption is developed.
Energy storing and recovering in loading and unloading cycles of forward loader
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
T. Virvalo and W. Sun,
2007,
pp. 255-267,
September 2007
view abstract
An important topic in R&D of mobile machines, for instance forest machines, is the improving of energy utilization. Important machines in timber harvesting chains are forward loaders. Booms of these kinds of machines are quite heavy and their reach range is large. The efficiency or energy utilization of these machines is quite poor. Loads under gravitational force are typical in loading and un-loading work cycles of forward loaders. Possibilities to utilize the gravitational force influencing one or two degree of freedom in some other degree of freedom are studied in a forward loader case. The basic idea studied is to use the outflow of the lift and jib cylinders to drive the telescope-cylinder. The outflows of the lift and jib cylinders are used directly or via the accumulator in the telescope-cylinder. Control valve assembly and accumulator are in very important roles in proposed method. The set-up and control strategy of valves are studied. The size of the accumulator is optimized taking care of environment and working condition. The energy consumptions of traditional and proposed systems are compared in different work cycles.
Enhanced control performance of a piezoelectric-hydraulic pump actuator for automotive transmission shift control
G. W. Kim and K. W. Wang,
In Proc. of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering,
2010,
volume 224,
pp. 161-174,
view abstract
In this research, a piezoelectric–hydraulic pump (PHP) actuator is synthesized for an automatic transmission (AT) test bed to demonstrate its potentials as a controllable powerby-wire actuator. This research expands from the previous investigations by enhancing the control performance of the PHP actuator developed for AT and bringing the study to the system level. Actuation force-tracking control using an on-site force transducer is proposed and a fill volume control strategy utilizing the AT turbine acceleration information is explored. The system level evaluation of shift performance is performed to demonstrate the effectiveness of
the proposed enhancements through a hardware-in-the-loop simulation environment.
Enhanced Performance and Stability in Pneumatic Servosystems With Supplemental Mechanical Damping
Keith W. Wait and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
Juli 2010
view abstract
The authors present a model-based analysis of a position-velocity-acceleration-controlled pneumatic actuator that indicates that supplementing the pneumatic actuator with mechanical damping can significantly increase the gain margin, tracking accuracy, and disturbance rejection of a closed-loop-controlled pneumatic servoactuator. In order to validate the model-based analysis and purported performance and stability benefits provided by supplemental damping, experiments were performed on a single-degree-of-freedom pneumatic servosystem. Measurements conducted on the experimental setup, which validate the respective improvements in stability margin, tracking accuracy, and disturbance rejection, are described.
Entropy Generation Reduction in a Rotor -casing Assembly using Inlet and Outlet Fillets
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
B. Abu-Hijleh and J. Tu and A. Subic,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 137-144,
November 2003
view abstract
Rotating machines, such as blowers and superchargers, are used extensively in the aerospace
and automotive industries. The efficiency of such components weight heavily on the overall
efficiency and performance of such engines. The inlet and outlet connections to a rotor’s casing
give rise to significant flow disruptions, which in turn results in significant energy losses from
the rotor assembly. Modifications to the rotor’s casing inlet and outlet are proposed and
optimised using Computational Fluid Dynamics (CFD) simulation. The simulation was carried
out for inlet and outlet fillet radii, inlet flow velocities, and rotor angular speeds. The flow
field results were used to ascertain the changes in quantities that affect the efficiency of a rotorcasing
assembly. This included changes in traditional quantities such as: inlet pressure,
maximum velocity magnitude and maximum recirculation velocity within the assembly, and the
maximum turbulence values. A more fundamental quantity, integrated entropy generation through
out the assembly, was also calculated. Entropy generation is based on the second law of
thermodynamic and accounts for all types of irreversibilties within the assembly. Of the
different traditional quantities reported, only the inlet pressure results were inline with the
entropy generation results. Overall, the results indicate that the properly sized inlet and outlet
fillets have a significant effect on the efficiency of a rotor-casing assembly.
Equalization techniques for dual redundant electrohydraulic servoactuators for flight control systems
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
G. Jacazio and L. Gastaldi,
2008,
pp. 543-557,
September 2008
view abstract
Electrohydraulic servovalves have been the most common device used to control the flow to hydraulic actuators in aircraft fly-by-wire flight control systems. Though servovalves offer several advantages, they present a few drawbacks, among which an unpredictably variable offset between hydraulic null and electrical null. In flight control systems at least two actuators supplied by two independent power sources and independently controlled are connected to the same flight control surface to provide the necessary redundancy; when the flows to the actuators are simultaneously and directly controlled by two servovalves, an unfavourable combination of servovalves offsets can originate a force-fighting condition with negative effects on the overall system stiffness, resolution and frequency response. This paper presents an optimal equalization control strategy capable of minimizing the force fighting between two redundant electrohydraulic servoactuators.
Erosion due to Impingement of Submerged Cavitating Jets in Tap Water, Biodegradable and Mineral Oils
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
T. Kazama and K. Shimizu,
2007,
volume 2,
pp. 91-105,
Mai 2007
view abstract
Using a submerged cavitating jet apparatus, a cavitation erosion experiment was performed. Tap water, synthetic type biodegradable oil, or mineral type hydraulic oils with ISO VG32 and VG46 were alternatively used as test liquids. The liquid temperature was maintained at 40–65°C. The upstream pressure was set at 10–18 MPa and the cavitation number was 0.02–0.04. The standoff distance was varied 10–35 mm. The
15-mm-diameter specimens were made of aluminum alloy. The main conclusions are the following. The mass loss with tap water was markedly greater than losses with any type of oil. The loss with VG32 was larger than the loss with VG 46. As the liquid temperature increased, the mass loss with the biodegradable and mineral oils increased proportionally.
The mass loss was approximately proportional to the fourth power of the upstream pressure. The surfaces were eroded as ring-shaped for all tested liquids. The surfaces
eroded by tap water were noticeably rough: severe damage was distinctly visible in SEM micrographs and photographs. Comparing the mass loss and processed images of
cavitating jets, the correlation between erosion and the jets was partially shown.
ESTABLISHING OPERATING POINTS FOR A LINEARIZED MODEL OF A LOAD SENSING SYSTEM
D. Wu and R. Burton and G. Schoenau and D. Bitner,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 47-54,
August 2002
view abstract
A load sensing system is one in which the pump flow is adjusted to keep pressure across an orifice constant and independent
of any variation in the load pressure. This ensures that the pressure losses across the orifice are kept to a
minimum which increases efficiency substantially. Because the system is closed loop, stability can become a problem.
To establish stability bounds, linearized analysis is often employed. However, to do this, operating points of all linearized
parameters and coefficients must be established as a function of certain parameters such as load pressure. This
can only be done by solving a series of nonlinear algebraic equations. This paper presents a set of equations for three
special conditions. The experimental verification of operating points that are predicted for such a load sensing system is
presented. The three regions are established theoretically and are verified experimentally. It is found that the operating
points undergo a noticeable change when in transition from one region to another (as dictated by variations in load pressure
or orifice area). It was also found that the agreement between the predicted and measured operating points was
quite satisfactory and could be used with confidence in future studies.
Estimation of stresses in components and gap in active contacts of epitrochoid generated floating axis ROPIMA type hydrostatic units- an FEM approach
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
A. Nag and S. Basu and R. Maiti,
2008,
pp. 129-136,
September 2008
view abstract
In earlier investigations by Maiti et. al. [1988-1993, 1999] active contact stresses, deformations and their effects on performances of the epitrochoid generated rotary piston machine (ROPIMA) type Low Speed High Torque (LSHT) hydraulic motors, namely ORBIT motors (Figure-1), were reported. In estimating the different parameters the static balance of rotor was considered by balancing the instantaneous forces and moments which needed a simplified analytical approach and trial and error in computation. In the present investigation we have used FEM to rigorously reinvestigate those results. We have considered total deformation of the rotor instead of only the contact deformation as in earlier case studies. As it was expected there are dissimilarities in results and we have extended our investigation to justify those. Our aim is to find the variation in the starting torque capacities affected by the initial sizes of such geometrically form closed rotor–stator. Variations in load holding torque and thereby the starting torque capacities as well as leakage path, with the variation in amount of interferences in initial fitting of rotor-will also be investigated. It is observed during FEM analyses that the patterns of stresses-deformations vary with the variation in the geometric design parameter set. It demands the redefining of element mesh. We have always tried into arriving in a unified approach. An animated view of ORBIT motor is also developed to study the kinematics and to understand the functional operations. The ultimate aim of this work is to arrive into a balance in reduction in inter chamber leakage in one hand and to increase the starting torque efficiency of the ORBIT motor on the other hand.
EVALUATION AND VALIDATION OF AN AIR SPRING ANALYTICAL MODEL
G. Quaglia and A. Guala,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 43-54,
Juli 2003
view abstract
The present paper responds to the following aim: to define a model, which can predict quite well the static characteristic
of a bellow spring. In detail an analytical non-dimensional model of the bellow spring is obtained. It can describe
the axial force and the effective area apart from its geometric size. The typical parameters of this model are
spring geometrical ratio and number of convolutions. No detailed information about membrane characteristic is required.
Internal volume and spring stiffness equations are then analytically derived.
At last a dynamic model of the spring is developed using the static characteristics previously defined. This tool
would be useful for particular applications that involve dynamics as a keyword, such as vibration isolators, vehicle
suspensions and actuators.
Evaluation of Effective Bulk Modulus of Oil in Hydraulic Dampers - Effects of Cylinder Shell Elastic Deformation
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
Ill-Yeong Lee,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 193-206,
März 2010
view abstract
This paper presents a theoretical model of cylinder shell bulk modulus (Kc) to achieve more accurate modeling of effective bulk modulus of oil (Kc) in hydraulic dampers. The theoretical model of Kc has been derived based on the elastic theory for thick-walled cylinder incorporating not only radial but longitudinal deformation. The new model on Kc was examined through numerical computations. A cylindrical container and a twin-tube type automotive damper were chosen as the objects of numerical computation. Kc itself and Kc in connection with Kc of the objects were computed with the new model and traditional models of Kc. By showing the computational results, the effects of Kc on Kc in automotive hydraulic dampers were explained clearly.
Evaluation of Energetic Possibilities and Ecological Characteristics of IC Engine and Hydrostatics Transmission System for Spectrum Form of Load
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
H. Chrostowski and W. Sradomski,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 569-577,
November 2003
view abstract
In following paper a general model of driving system is presented: IC engine - hydrostatic
transmission - load, in the form of area with specified spectrum of variables: torque and velocity.
Those models enable the analysis of efficiency of hydrostatic driving system and points of work of
IC engine in the field of load characteristics. Mathematical models of the components of the driving
system, for the analysed case, are the results of the experimental examination. The originally
introduced concepts of global efficiency and ecological indexes are suitable to compare the quality
of driving systems working in the same, statistically, load conditions. It allows the evaluation of
value of those parameters in the whole life, functioning, of a machine. It is possible through
determination for each point of load the optimal control of the displacement unitary volume of the
pump and motor.
Evaluation of Linear and Non-Linear Control Schemes Applied to a Hydraulic Servo System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. O. Andersen and M. R. Hansen and H. C. Pedersen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 859-863,
April 2005
view abstract
Due to the innovation of low-cost electronics such as sensors, microcontrollers etc., the focus on high-performance motion control is increasing. This work focuses on position control of single-input single-output hydraulic servo-systems in general. A hydraulically actuated robotic manipulator is used as test facility acting as load for the hydraulic servo system. An experimentally verified non-linear model of the complete system has been developed and used to design a series of both linear and non-linear control schemes. The controllers from each category are compared with respect to design parameters such as performance, robustness and implementation.
Experiences of Fluid Flow Modelling in the Design of Mobile Hydraulic Oil Tanks
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
J. Rinkinen and D. H. Ahlstedt and T. Nurminen,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 123-136,
November 2003
view abstract
The flow field in two mobile hydraulic oil tanks has been analysed using computational fluid
dynamics (CFD). It has been made modifications to the original tank in order to obtain
uniform flow field and better separation of air bubbles and water droplets. Some experiences
are presented and discussed both in area of modelling and oil tank designing.
Experimental Analysis of HIL Simulator with Flow/Pressure Interface
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Eskola and P. Pedersen and H. Handroos,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 14-17,
April 2005
view abstract
The present paper deals with hardware-in-the-loop (HIL) simulation of hydro-mechanical systems. A key sub-system of the proposed simulator is the flow-pressure interface between real and virtual processes.
A robust controller for flow control in the interface System is studied and designed in z-domain. The designed controller is a combination of a feed forwarded inverse servo-valve model and a secondary PI controller, whose gains are depending on the pressure drop over the controlled valve. A computational approach is applied to obtain optimal gains in different operating Points. A gain scheduling algorithm is tested in order to improve the robustness of the transient response. Some test simulations are made in the time domain. Finally the controller is tested in lab with a real HIL simulator.
Experimental and Control Research on Pressure Impact during Spool Shifting of Directional-control Valves
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. Binxiang and C. Guoan and F. Tianjin and Y. Sheng and W. Genmao,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 873-876,
April 2005
view abstract
The main factors affecting pressure impact in open hydraulic circuit during switching of spool-type directional-control valves, and their affecting extent are analyzed theoretically in this paper. Modem electro-control technology is adopted to regulate timely oil pump's displacement to realize optimal matching between the output of the oil pump and the requirement of a hydraulic system. In addition, a hydraulic accumulator is installed in the return line as an assistant measure. The pressure impact resulting from spool shifting is reduced extremely, and the aim that a hydraulic system is energy-saving, environment-protecting, and reliable is realized really. Experimental studying for those measures' validity in the concrete pump model HBTS60 is carried out systematically, and satisfactory effects are acquired.
Experimental and modelling research of load compensated hydrostatic driving systems
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Bartnicki and F. Kuczmarskij,
2004,
pp. 17-23,
Juni 2004
view abstract
In this paper the results of experimental research of static and dynamic properties of hydraulic systems
with load compensation which were done at laboratory stand for research of LOAD SENSING hydraulic
systems are presented. There is also proposal of functional simulation model which is developed in
Simulink programme. The examples of experimental research results are shown. The usefulness of this
model for simulation research of LS systems has been determined.
Experimental and Numerical Analysis of the Flow Forces on an Open-Centre Directional Control Valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. Del Vescovo,
2004,
pp. 83-92,
Juni 2004
view abstract
The aim of the present work is an experimental and numerical analysis of the driving forces acting on
a 4/3 hydraulic open centre directional control valve. The valve is inserted in a closed hydraulic circuit
and it is tested with different pump flow rate values. The valve assembling has been modified to allow
the external control of the spool displacement and the flow force measurement. The results thus
obtained are reliable and show important differences between an open centre valve and a closed centre
valve extensively analyzed in literature [Batoli, 1996; M.Borghi et al, 2000; Del Vescovo et al, 2002,
2003].
A particular trend of the flow forces is obtained in the first part of the sliding spool travel, since, in this
phase, the flow force is advantageous for the spool opening. The paper presents a complete numerical
analysis of the flow inside the valve after a simplified geometrical modelling. The commercial code
“Fluent” has provided good numerical results dealing with the peak flow force value and its position,
the recirculation flow rate distribution and the average fluid dynamic angles in the connection
surfaces.
EXPERIMENTAL AND NUMERICAL INVESTIGATION FOR DOWNSIZING OF OIL RESERVOIR BY BUBBLE ELIMINATOR
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
T. Kobayashi and Y. Tanaka and R. Suzuki and M. Ochiai,
2006,
volume 2,
pp. 397-408,
Juni 2006
view abstract
In mobile hydraulic systems such as commercial vehicles, hydraulic fluids are splashed and agitated in the reservoirs.
To overcome air entrainment in oils, the overall dimensions should enclose a sufficient volume of oil to permit air
bubbles to escape passively during the resident time of the fluid in the reservoir. However, in view point of
environmental compatibility, energy saving, cost saving and safety, one trend in fluid power systems is to be designed in
a more compact fashion and requiring less fluid in the reservoir. Recently a newly device using swirl flow for bubble
elimination capable of eliminating bubbles and of decreasing dissolved gases has been developed. This device is called
the Bubble Eliminator. In our previous study, we have reported that the bubble eliminator is useful for preventing oil
temperature rise caused by the bubbles under low, moderate and high system pressure conditions.
In this paper we focus on the technical issue for the air bubbles and oil temperature rise in the reservoir of test
hydraulic circuit under the filed test of the construction machinery. Performance of the bubble eliminator is
experimentally evaluated by measurement of oil temperature rise in the reservoir of the test hydraulic circuit. Flow
pattern in the bubble eliminator has great influence on the performance of bubble removal. Numerical analysis of the
flow in the bubble eliminator is also carried out to investigate the influence of separating the air to the oil. It is
numerically and experimentally verified that the bubble eliminator can effectively reduce the oil temperature rise.
The bubble eliminator solves many problems concerning the air entrainment in mobile hydraulic systems. Some
advantages of using the bubble eliminator as a design option is also discussed. Use of the bubble eliminator for the
fluid power system may allow the hydraulic designer to reduce the system’s reservoir size.
Experimental and Numerical Investigation of the Squeeze Mode of Magneto-Rheological Fluids
Schriftreihe der Technischen Universität Wien
N. Gstöttenbauer and A. Kainz and B. Manhartsgruber and R. Scheidl,
TU Wien,
ed. R. Flesch and H. Irschik and M. Krommer,
2004,
volume 1,
view abstract
Magneto-rheological (MR) fluids represent a class of smart materials, the rheological properties of which can be controlled by the application of an external magnetic field. The MR-fluid offers three modes of operation. Only two of them are frequently used in applications: Either the direct shear mode, where the relative motion of two magnetic poles separated by the fluid generates shear forces, or the valve mode, where the magneto-rheological effect is used to restrict the flow through passages and the resulting pressure difference is used for hydrostatic force generation. Because of its non-linear behaviour, the third mode of operation, the so called squeeze mode is up to now used for small amplitude vibration damping only. A better insight into the behaviour of MR-fluids in the squeeze mode is expected to give rise to new applications. A test rig for the exploration of the fluid behaviour in the squeeze mode, Ref [1] was used to obtain measurement data. The present paper describes the results of measurements from this test rig in single squeeze as well as periodic squeeze experiments showing the highly complex material properties of MR-fluids. Distinct hysteresis behaviour and cyclic hardening takes place due to the formation and disruption of iron particle chains along the magnetic field lines which is part of further investigations and has to be understood in more detail. Describing this material behaviour numerically is a challenging task. Finding a material law goes far beyond using rather simple elasto-viscoplastic material laws implemented in commercial Finite Element codes. Therefore, highly sophisticated continuum theory techniques have to be applied in principle.
EXPERIMENTAL AND SIMULATION RESULTS OF APPLYING FUZZY GAIN- SCHEDULING IN POSITION CONTROL OF A SERVO HYDRAULIC SYSTEM WITH FLEXIBLE LOAD
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
H. Yousefi and H. Handroos,
2006, August 2006
view abstract
The control of hydraulic servo-systems has been the focus of intense research over the past decades. Hydraulic posi-tion servos with an asymmetrical cylinder are commonly used in industry. These kinds of systems are nonlinear in na-ture and generally difficult to control. Because of changing system parameters using the same gains will cause over-shoot or even loss of system stability. The highly non-linear behavior of these devices makes them idea subjects for applying different types of sophisticated controllers. This paper is concerned with a second order model reference to positioning control of a flexible load servo-hydraulic system using a fuzzy gain scheduling. In present study, to com-pensate the lack of damping in hydraulic system, an acceleration feedback was used. The proposed controller was veri-fied with a common used p-controller. The results of experiments and simulations suggest that using fuzzy controller improves all performance evaluation criteria such as stability, fast response, and accurate reference model tracking in hydraulic systems.
Experimental and theoretical study of the electrical failures in a fault-tolerant direct-drive servovalve for primary flight actuators
G. Di Rito and R. Galatolo,
In Journal of Systems and Control Engineering: Proceedings of the Institution of Mechanical Engineers,
2008,
volume 222,
pp. 757-769,
Dezember 2008
view abstract
The current paper deals with the study of the electrical failures in fault-tolerant flight actuators, with particular reference to the short circuits of the servovalve coils. A highfidelity model of the servovalve of a modern fly-by-wire actuator is developed and validated through experiments, focusing attention on the characterization of the component dynamic in case of partial and total short circuits of the direct-drive motor coils. The servovalve model is then used to simulate a typical on-ground built-in-test procedure to determine the limit condition for the detection of a partial short circuit. Finally, one different possible combinations of short circuits are injected, the degradation of performances of the whole actuator is characterized through experiments, and the servovalve model is used to justify the test results, highlighting and discussing the effects of the failures on the system dynamics.
Experimental assessment of a free elastic-piston engine compressor with separated combustion chamber
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
J. Riofrío and E. Barth,
2008,
pp. 233-244,
September 2008
view abstract
This paper presents the experimental assessment of a free elastic-piston compressor (FEPC) equipped with a separated combustion chamber. The FEPC is a proposed device that utilizes combustion of a hydrocarbon fuel to compress air into a high-pressure supply tank, thus potentially serving as a portable power supply candidate for untethered pneumatic systems of human-scale power output. The design and simulation of the FEPC concept have been shown in previous work, and the device's energetic merit outlined. The free "piston" consists of a custom-molded silicone-rubber membrane, clamped at the circumference, thus providing perfect blow-by sealing and near zero friction. The device is equipped with a custom-built separated combustion chamber, which dynamically channels high-pressure combustion products of a hydrocarbon fuel in order to produce power strokes. Experimental results coupled with high-speed video are presented which verify 1) the operation of the separated combustion chamber including its air/fuel mixture control, 2) the dynamics of the combustion valve in first sealing the pre-combustion gases and then venting the combustion products into an expansion chamber, 3) the dynamics of the free piston in converting pressure energy in the expansion chamber into kinetic energy, and 4) successful pumping of air into a reservoir.
Experimental Based Analysis of the Pressure Control Characteristics of an Oil Hydraulic Three-Way On/Off Solenoid Valve Controlled by PWM Signal
Heon-Sul Jeong and Hyoung-Eui Kim,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 196-205,
März 2002
view abstract
Pressure control characteristics of a three-way high-speed on/off oil hydraulic solenoid valve driven by a PWM signal with a fixed pulse period were theoretically and experimentally analyzed and evaluated. By virtue of its relatively low cost, small size, robustness to contamination, and simplicity of the driving circuit, the three-way on/off solenoid valve is increasingly and widely used for hydraulic pressure or position control applications. In this paper, two formulas are newly derived for the mean and the ripple amplitude of the system pressure that oscillates with the same frequency as that of the PWM driving signal. The formulas indicate that the mean pressure and the pressure ripple amplitude depend on three major system variables that are the on- and the off-times of the valve and a parameter, the system configuration coefficient a, that characterizes the overall feature of the system. The mean pressure and the ripple are then shown to depend on both the duty ratio and the carrier frequency of the PWM driving signal, which disproves Tanaka's claim that a single variable is enough to describe two quantities. Several aspects of the formulas are discussed. The accuracy of the new formulas is verified by comparing the calculation results to corresponding experimental test results. A method is proposed to obtain the system parameters of the opening and closing-case delay times, the time constants of the valve and a. The selection criteria are established for the major design parameters of the driving signal, i.e., the duty ratio and the carrier pulse frequency, and a basic strategy is proposed on how to suppress the undesirable ripple for a hydraulic servo control system using three-way on/off solenoid valve.
Experimental-based Modelling and Simulation of Water Hydraulic Mechatronics Test Facilities for Motion Control and Operation in Environmental Sensitive Applications' Areas
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
F. Conrad and J. Pobedza and A. Sobczyk,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 553-568,
November 2003
view abstract
The paper presents experimental-based modelling, simulation, analysis and design of water
hydraulic actuators for motion control of machines, lifts, cranes and robots. The contributions
includes results from on-going research projects on fluid power and mechatronics based on
tap water hydraulic proportional valves and servo actuators for motion control and power
transmission undertaken in co-operation by Technical University, DTU and Cracow
University of Technology, CUT. The results of this research co-operation include engineering
design and test of simulation models compared with two mechatronic test rig facilities
powered by environmental friendly water hydraulic servo actuator system. Test rigs with
measurement and data acquisition system were designed and build up with tap water
hydraulic components of the Danfoss Nessie® product family. This paper presents selected
experimental and identifying test results for a water hydraulic system.
Experimental Characterization and Gray-Box Modeling of Spool-Type Automotive Variable-Force-Solenoid Valves With Circular Flow Ports and Notches
M. Cao and K. W. Wang and L. DeVries and Y. Fujii and W. E. Tobler and G. M. Pietron,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 636-654,
September 2006
view abstract
In automatic transmission design, electronic control techniques have been adopted through proportional variable-force-solenoid valves, which typically consist of spool-type valves (Christenson, W. A., 2000, SAE Technical Paper Series, 2000-01-0116). This paper presents an experimental investigation and neural network modeling of the fluid force and flow rate for a spool-type hydraulic valve with symmetrically distributed circular ports. Through extensive data analysis, general trends of fluid force and flow rate are derived as functions of pressure drop and valve opening. To further reveal the insights of the spool valve fluid field, equivalent jet angle and discharge coefficient are calculated from the measurements, based on the lumped parameter models. By incorporating physical knowledge with nondimensional artificial neural networks (NDANN), gray-box NDANN-based hydraulic valve system models are also developed through the use of equivalent jet angle and discharge coefficient. The gray-box NDANN models calculate fluid force and flow rate as well as the intermediate variables with useful design implications. The network training and testing demonstrate that the gray-box NDANN fluid field estimators can accurately capture the relationship between the key geometry parameters and discharge coefficient/jet angle. The gray-box NDANN maintains the nondimensional network configuration, and thus possesses good scalability with respect to the geometry parameters and key operating conditions. All of these features make the gray-box NDANN fluid field estimator a valuable tool for hydraulic system design.
Experimental Characterization of Critical Dynamic Model Parameters for a Free Liquid Piston Engine Compressor
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
J. A. Willhite and E. J. Barth,
2010,
volume 2,
pp. 425-433,
Juni 2010
view abstract
The use of a free liquid-piston engine compressor (FLPC) as an on-board pneumatic power supply for untethered
human and sub-human scale autonomous robotic systems is being investigated. The liquid piston’s geometry exploits
fluid inertance to achieve slower overall system dynamics than an equivalent mass solid piston so that efficient
compression and pumping can occur without prohibitively large pump valve size or piston mass. A dynamic analysis,
along with the traditional thermodynamic analysis, of the engine has been developed due to the engine’s dynamically
dominant nature. Within this dynamic model, it is important to accurately characterize the critical subsystems of the
engine. This paper focuses on the measured and experimentally derived parameters of three of these subsystems—liquid
piston diaphragm stiffness, injection valve capacity and dynamic response, and pump check valve dynamics. A
discussion of the implications of these parameters on the overall FLPC design and performance is also presented.
Experimental Evaluation of a Metering Poppet Valve
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
R. Fales and C. Li,
2008,
pp. 495-508,
September 2008
view abstract
In this Work, a model with experimental validation is developed for a unique electro hydraulic flow control valve. The model is intended to be used for control design and simulation of hydraulic systems. The valve is a unique design developed at the University of Missouri with two stages: a pilot stage and a main stage. Both stages employ poppet valves rather than more common spool valves. The dynamic response is analyzed through the use of experiments. The experimental dynamic response is compared to that of a nonlinear and a linear simulation. A linear model is developed to agree with the experimental responses. Since the performance is found to vary based on changes in operating conditions, a model of the error is also determined using frequency domain techniques. The error model can be used in robust stability analysis for future control system designs.
Experimental Evaluation of a Piston-Type Digital Pump-Motor-Transformer with Two Independent Outlets
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Heikkilä and J. Tammisto and M. Huova and K. Huhtala and M. Linjama,
2010,
pp. 83-97,
September 2010
view abstract
The digital pump-motor-transformer is a new energy-efficient alternative to the fluid power system. Based on digital (stroke to stroke) control of each piston of the pumping unit, its functionality consisted of (1) an arbitrary number of independent outlets, (2) service of each outlet at arbitrary pressure levels, (3) energy recovery from each outlet back to the prime mover, (4) power transfer from one outlet to another at arbitrary pressure levels, and (5)
energy storage in and recovery from a hydraulic accumulator independent of pressure.
Theoretical analysis and simulations show that the principle works and is highly efficient.
This paper reports the first experimental results on the principle. The prototype pumpmotor-transformer consisted of a six-piston inline pump, fast on/off control valves, and two
independent outlets. The system was measured for its efficiency, controllability, energy transformation, and flow sharing functionality. The results are encouraging but show also that more pistons are needed for smooth flow rates.
Experimental identification of inertail and friction parameters for electro-hydraulic motion simulators
C.-T. Chen and J.-C. Renn and Z.-Y. Yan,
In Mechatronics,
2011,
volume 21,
pp. 1-10,
Februar 2011
view abstract
The fullness of dynamics equations and the degree of uncertainty in dynamic parameters are important factors in application of the identified models to model-based control strategies. Therefore, in this paper, the experimental identification of inertial parameters and friction coefficients are dealt with for an electro-hydraulic motion simulator, normally consisting of the Stewart platform. The model with arbitrary geometry, inertia distribution and frictions are obtained based on a structured Boltzmann–Hamel–d’Alembert formulation, and then the estimation equations are explicitly expressed in terms of a linear form with respect to the base parameters of minimal dimension to be identified. The identified parameters are obtained through solving the estimation equations by simple least square method. Moreover, exciting trajectories are also designed respectively in the actuating space and task space. Finally, the identified parameters are used to validate the developed model by comparing the predicted forces with respect to the actuating forces for a random trajectory.
Experimental Implementation of a Neural Simulator
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
X. Ping and R. Burton and C. Sargent,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 21-26,
November 1997
view abstract
This study investigates the use of neural networks to identify transient responses of a nonlinear system, with a long term objective of developing neural simulators of actual systems that are to be incorporated into simulation packages. The study focuses on the experimental work of modeling a hydraulic load sensing pump using an established neural net approach. An experimental system is designed and constructed with particular attention to the design and generation of sufficiently rich input signals. The data sampled at an appropriately chosen sampling rate from the testing of the load sensing pump dynamics are used to train and validate the neural models. The study carefully examines the problems and constraints (not revealed by theoretical or simulation studies) imposed by the actual experimental system. The modeling results with two neural model configurations are presented in this paper and establishes, from a practical point of view, the potential of the neural network approach to modeling a real hydraulic component. In addition, it is shown that the training accuracy and the error accumulation are the two most critical factors in examining and interpreting modeling accuracy.
Experimental investigation and theoretical prediction of the lubricity of biofuel components
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
A. Fatemi and K. Masuch and H. Murrenhoff and K. Leonhard,
2010,
pp. 39-51,
September 2010
view abstract
In the design of fuel supply pumps and injection units, the tribological properties of the fuel are an essential concern. This is because the majority of high-pressure injection systems are fuel-lubricated and rely on the lubrication ability of the fuel itself. Therefore the lubricity of biobased pure compounds is investigated via high-frequency reciprocating rig (HFRR). A novel method employing COSMO-RS and theory of adsorption is adopted in order to find a correlation between molecular structure and tribological properties of fuel components. From a more general perspective, this concept can be used for the analysis of the tribological characteristics of components of biodegradable hydraulics fluids.
EXPERIMENTAL INVESTIGATION OF THE DYNAMIC PROCESSES AND PARAMETERS IDENTIFICATION IN ELECTROHYDRAULIC POWER SYSTEM
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
H. N. Hristov,
2002, Juli 2002
view abstract
Processes investigation in electrohydraulic power transmission determinate the performance specification and
qualities statements at steady-state and transient operation. The investigation of linear models almost but not quite
determinate the behaviour of system in different operations rates, because there are many inherent nonlinearities. The
formulation and investigation of nonlinear mathematical model, which involve nonlinear element is of interest. This
paper is shown an mathematical model of nonlinear electrohydraulic power transmission. Influence of the basic
parameters variations of nonlinear system have been investigated. There are shown the dynamic processes in the system
obtained by computer simulation in comparison with experimental results. In this paper is shown an automated test
stand for dynamic processes investigation in electrohydraulic power systems and a method for unknown parameters
identification in electrohydraulic power system. Process control and experimental data collection and preservation are
realised with personal computer in “real time”. The data from experimental investigation is used. The differential
equations of the electrohydraulic system are derived. The uncertain parameters of electrohydraulic system mathematical
model is obtained with a special software in a PC. The experimental and theoretical processes before and after the
identification procedure is shown. The dynamic processes are modelled and simulated in PC for different conditions.
The obtained step time responses are shown in few graphics. This gives opportunity for correct evaluation of to the
accuracy of hydraulic actuator motion in static and in dynamic conditions.
Experimental investigation on a hydraulic special poppet valve
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Vacca and G. Franzoni and P. Casoli,
2004,
pp. 567-577,
Juni 2004
view abstract
This paper describes the experimental investigations carried out on a special relief and anti-cavitation
valve. This component is usually connected to a hydraulic line with the aim of keeping the circuit pressure
between two different set values. The valve works as well as anti-shock valve to avoid pressure peaks; on
the other hand it can work as anti-cavitation when the pressure is too low. In order to realize these
purposes in a small insert cartridge structure, the valve is provided of a stem, shaped as a cone ending with
a cap, that moves inside a sliding seat.
In this work the relief and anti-shock valve was experimentally investigated; the valve behaviour was
identified by pressure drop versus flow rate diagrams. Several tests were first carried out for different
stock valves (differing for valve calibration). It was observed that the particular slider geometry implies a
good behaviour, close to the ideal one: the pressure drop course is rather flat independently of the flow
rate. Afterwards a special prototype was realized, so modified as to permit the slider to be locked in
several given positions. In this way the equivalent discharge coefficient (as a function of the stem
position) of the valve was determined.
Finally different stems were realized (differing in cap diameter) and tested with the aim of understanding
the influence of stem geometry on valve behaviour.
All the experimental tests were performed on a test rig for hydraulic units, located in Casappa S.p.A.
laboratories. The paper reports the most significant experimental results. The work also describes the
experimental apparatus, analyzing the accuracy of the results provided.
Experimental Investigation on Flow Characteristics of Annular Gap Damper in Water Hydraulics
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
N. Songlin and W. Zhengjiang and Z. Yuquan and L. Zhuangyun,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 189-193,
April 2005
view abstract
Owing to large cross-sectional area the annular gap damper can easily ensure its flow rate to be laminar, which is widely used in hydraulic components, especially in water hydraulic control components. The flow-pressure characteristics of the annular gap damper and relationship between the flow-correction coefficient and overlap length are investigated experimentally. For annular gap damper, the water flow is much less than that of oil as working medium under the same pressure difference and overlap length. The flow-correction coefficients for the laminar inceptive phase are approximately constant for different overlap lengths, ranging from about 1.3 to 5 when l = 5 ~ 25 mm. The experimental results indicate that, cavitation in the annular gap damper cause vapor bubbles to collapse and choke, and produce decreased flow. The relevant research on the annular gap damper will be useful to the designs of water servo valve and other water hydraulic control components.
Experimental Investigation on Swash plate - Piston slipper Lubrication in Hydrostatic Units
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
K. Choudhuri and R. Maiti,
2004,
pp. 51-58,
Juni 2004
view abstract
The main objective of this investigation is to estimate the frictional or the viscous drag torque due to the sliding motion of piston slipper pad on swash plate of inline piston hydrostatic units, i.e., hydraulic motors and pumps, at different pressure and speed. Swash plate controlling torque, with respect to the multi-piston behaviour on swash plate, is targeted. However, in the present work loss due to friction between piston slipper pad and swash plate for single piston with Newtonian fluid (mineral based hydraulic oil) is studied both theoretically and experimentally. An experimental set-up is developed for measuring the torque on the swash plate due to piston slipper tribology on swash plate. The measurements of pressure, speed and deflection of a beam, which is holding the reaction torque of a plate performing the role of swash plate, have been carried out. Finally the variation of torque with pressure and speed are calculated. Torque on swash plate due to tribology of slipper pad is estimated. Finally the coefficient of friction with generated oil film has been proposed for different speeds and pressures.
EXPERIMENTAL INVESTIGATIONS OF GUIDE RINGS MADE OF UHMWPE AND PTFE COMPOSITE IN WATER HYDRAULIC SYSTEMS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
W. Okularczyk and A. Sobczyk,
2008,
pp. 501-508,
Juli 2008
view abstract
In the present work two materials of guiding elements were tested in water hydraulic. During investigations of hardness
conducted for stuffing box packings in water hydraulic systems an analysis of proper selection of piston rod guiding
elements has also been carried out. ø 45 f7 (Ra = 0.07÷0.20 μm, Rm ≤ 2.5 μm). Working piston rod has been used for
investigations made of chromium-nickel steel AISI 431 (Cr=16.7%, Ni=2.08%). Some of the guiding elements, after
proper selection of the material, could be still used, despite damaged seal. The tests have been performed maintaining
water pressure on the sealing at a level of p = 8±1 MPa and the average velocity of the piston rod of v ≈ 0.35 m/sec.
Water temperature during investigations was regulated within the range of Tmin = 291 K and Tmax = 305 K. Variable
value of friction coefficient has been obtained for the guide rings made of PTFE composite with the change in piston
rod velocity. Application of guide rings made of UHMWPE has been estimated negatively.
Experimental Measurement and Numerical Simulation of the "Inter-Teeth Space Pressure" in External Gear Pumps
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
M. Greco and A. Vacca and P. Casoli,
2010,
volume 2,
pp. 537-550,
Juni 2010
view abstract
This paper presents the latest advances of an experimental activity performed on an external spur gear pump, using a
telemetry system to carry out a non intrusive measurement of the internal pressure. The experimental apparatus is
based on a prototype derived from a particular gear pump in production and equipped with a miniaturized pressure
transducer fixed inside a single tooth space volume at the root of the driver gear. A particular attention on the sensor
fixation has allowed the isolation of the receptive transducer head from stresses and strains generated by meshing of
gears teeth. A special investigation has been carried out to estimate the influence of torsional deformation of the
meshing gears on the transducer side. A detailed description of the experimental apparatus, as well as the explanation
of the methodology utilized for its calibration, are also provided. Moreover, this work presents a comparison between
the results obtained by the experimental activity with the numerical simulations performed with the tool HYGESim
(HYdraulic GEar machine Simulator). A detailed comparison between the experimental trend and the simulated one is
shown for various operating conditions and the great potentiality of this numerical tool, used also for design purposes, is demonstrated. The developed test rig permits not only to validate the simulation model, but also it allows a clear understanding of the flow through the pump by means of simultaneous acquisition of the pressure inside a tooth space
volume on the driver gear, the gear angular position and of the instantaneous pump pressure at the delivery port.
Experimental Measurements of Static Friction for Line Contacts at High Speed Step Inputs
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
J. Garcia and A. Martini and J. Lumkes,
2010,
volume 1,
pp. 407-416,
Juni 2010
view abstract
The goal of this project was to measure the static friction coefficient in line contacts for dry and lubricated conditions
between metallic surfaces. Two cylinders were fitted in a test apparatus to produce a normal and tangential force for
the determination of the static friction. The experiment used a high resolution laser displacement sensor and an
electronic pressure regulator to enabled fast acting inputs. Both cylinders were fitted with compression load cells to
measure normal and friction forces. The displacement sensor was used to accurately measure the onset of movement as
opposed to the conventional method of using the peak friction force. Test results showed that the static coefficient of
friction is dependent on the contact characteristics and inputs and not the specific materials in contact
Experimental Research for Flowing Characteristics of Liquid in Micro Channels
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Zhiyong and S. Shangwu and Y. Jichang and D. Jianning and F. Zhen and L. Changsheng and Y. Ping,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 403-406,
April 2005
view abstract
With the development of Micro-Electro-Mechanical-Systems (MEMS),the microscale flow characteristics had attracted the great interests of scientific researchers. The key question is whether the macro flow rules are still valid or the micro flow has its own special flow characteristics which can be altered from the macro flow rules or it is a whole new theory. All these questions must be experimented to gain the final result. In this paper, the behavior of liquid was studied in microchannels with diameters ranging from 13pm to 100pm. By using different microtube diameter and length to explore the flow characteristics of microfluids. The results are basically in accordance with macroscale conventional theory; the N-S equation still acts well.
Experimental Studies of Flows Inside Gerotor Pumps with Use of High-speed Digital Camera
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
P. Antoniak,
2010,
volume 2,
pp. 691-698,
Juni 2010
view abstract
The achievements of gerotor pumps are similar, but not the same, to those of the other kinds of the internal involute
gear pumps. One of the most recent experimental methods used to improve the achievements of these pumps is using the
high-speed digital camera which makes possible to visualize the flow processes inside the internal channels of the
pumps. On the basis of this observation it is possible to determine the dangerous areas (e.q. the areas where the
cavitation might occur) of the channels which should be redesigned. In this article, the application of the method, for
investigation of the real fluid flow in the gerotor pump is going to be shown.
Experimental Study of Sealing Capability of Large Diameter Rotary Face Seals for Fluid Power Applications in Process Industry
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
O. Calonius and H. Hänninen and M. Pietola,
2007,
volume 2,
pp. 213-228,
Mai 2007
view abstract
The costs of sealing failure in industrial fluid power systems are likely to be quite high, because costs other than the cost of just replacing the damaged seal are involved. In
addition to economic factors, the quest for reliable solutions is driven by environmental legislation factors. In this study, full scale testing of face seals 531 mm and 534 mm in
diameter made of filled polytetrafluoroethylene was conducted in a new test rig. The seals were tested by varying both the sliding speed, ranging from 8.3 m/s to 19.6 m/s, and the
seal cross-section compression, ranging from 1.2 mm to 2.2 mm. For each set of test variables, three repetitions were made. Leakage values, temperatures near the sealing zone
and values of friction and frictional power are reported. With the test rig the operating conditions could be systematically varied and recorded. It was found that increasing in the
speed of rotation reduced the leakage. This tendency increased with the amount of compression. It was concluded that in the tested sealing system the leakage oil was partly
centrifuged back to the oil side of the sealing lip, such that leakage values represented the equilibrium between flow into and flow out of the sealed space. Least leakage throughout
the sliding speed range is likely to be produced with the seal type having a stiffer spring and greatest compression. However, this combination created a high sealing force resulting
in high frictional power loss and high operating temperature, which emphasizes the need for arranging good lubrication conditions in sealing systems involving high sliding speeds.
Experimental Study on Cavitation Characteristics of Water Hydraulic Orifice
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Yinshui and W. Zhengjiang and Y. Yousheng and L. Zhuangyun,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 204-207,
April 2005
view abstract
In this paper, experimental study is made on cavitation characteristics of water hydraulic orifice. All the orifices are made of transparent materials, so the flow status can be observed nakedly. The test for each orifice is carried out under the two cases of with and without backpressure. Experimental results illustrate that the cavitation characteristics of orifice with larger ratio of length and diameter are less influenced by backpressure. The cavitation occurs at the inlet of orifice at first and shifts to the outlet gradually. When there is cavitation happening at the outlet, flow saturation emerges simultaneously.
Experimental Study on Electrification Phenomena in Dielectric Liquid Flows over Metal Walls
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Takahashi and Z. S. Xin and S. Washio and I. Fujihara and D. Miki,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 130-133,
April 2005
view abstract
The present paper deals with an experimental study of electrification phenomena occurring between a metal wall and a dielectric liquid flowing over it. Measurements were carried out using a hydraulic mineral oil and a fluorocarbon as test liquids and wire meshes made of stainless steel, copper, brass and aluminium. The findings are as follows; the mineral oil was charged negative against stainless steel, copper and brass but positive against aluminium, while the fluorocarbon was charged positive against anyone of these four metals. Electric charges detected as currents out of the wire meshes increased with the Liquid velocity passing through the meshes and differed depending on the metal type even if the velocity was the same. Moreover, it was confirmed that contact of metal with a flowing liquid not only generates but also relaxes electric charges; the amount of charges either generated or relaxed per unit volume of the liquid flowing over metal decreases as the
flow becomes faster.
Experimental Study on Orifice-Liquid Distributor
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J. Zhang and Z. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 845-848,
April 2005
view abstract
The experimental study on 10 types of orifices is carried out to reveal the flow coefficient Cd vs Renault number in this paper. The Experimental results show that when Re is larger than 10000, Cd is almost unchangeable and is in range 0.61- 0.96 and it only varies with the structure of orifice. When Re is less than 10000, Cd changes sharply and complicatedly. Practically for the most liquid distributor, Re is less than 10000. Therefore it's unreasonable to consider flow coefficient as a constant in engineering design. Based on the experiments on the orifice distributing equipment, this paper put forward a more reasonable method to determine the value of the coefficient Cd, and the recommended value of Cd is presented according to the experimental results.
Experimental Study on the Performance of Large Diameter Shaft Seals with Laser Micro-structured Counterface
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
H. Hänninen and O. Calonius and M. Pietola,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 275-286,
März 2010
view abstract
Sealing components are a significant factor in ensuring the operational capacity and reliability of machinery. In order to secure the long-life and reliable operation of seals the lubrication and cooling of them must be ensured. For this study a new laser micro-structured counterface has been devised and implemented in a full scale test rig for large diameter radial lip seals. In special sealing applications involving large diameter rotors there is a demand to be able to cope with sliding speeds as high as 30 m/s to 40 m/s. Micro-structuring has previously been used in bearings and mechanical seals. In this study, the operation of elastomeric seals running against a micro-structured counterface with recesses of dimple and triangle shapes was compared to the operation involving a regular counterface. The results showed that even if leakage rates remained acceptably low, no reduction in seal lip temperatures or friction could be attained and thus no clear justification for using micro-structuring was found.
Experimental study on the use of a dynamic neural network for modelling a variable load sensing pump
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
L. Li and D. Bitner and R. Burton and G. Schoenau,
2007,
pp. 175-188,
September 2007
view abstract
Conventional approaches to modeling use physical knowledge of the system behavior to develop describing equations which can be analytically or numerically solved. The use of input and output data for model identification is also a very powerful modeling technique. The approach used in this study also uses input and output information but makes no attempt to relate the information to any analytical form or physical phenomena. It is a “black box” approach which employs dynamic artificial neural networks as its basis. Such models are particularly useful when the physical relationships, nonlinearities and parameter values of the system are very difficult to measure or quantify.
This study involves a variable displacement pump which does display complex properties and relationships. The intent was to obtain a black box model of the pump which would capture both the steady state and dynamic characteristics of the pump and which then would be integrated into a system model for a load sensing unit. The paper presents a particular modeling form that defines what the input and outputs of the model should be. The paper also introduces dynamic neural units and dynamic neural networks which constitute the “innards” of the black box.
In the first phase of the study, a nonlinear model of a variable displacement pump (verified experimentally in other studies) was used as the “plant” to be modeled. The dynamic neural network could be trained to capture the dynamic properties of the pump but the steady state performance was unsatisfactory. The approach then was to manually develop a modification equation or postprocessor to compensate for the steady state error. This approach was very successful in that the model output could follow the actual plant output in a satisfactory manner for many different input shapes.
In the second phase of the study, the compensation equation was not deemed to be an acceptable or practical way to reduce the steady state error. A static neural network replaced the compensation equation and trained to “learn” the compensation equation. This approach was also very successful with both the static and dynamic characteristics being captured by the neural based black box.
The third phase of the study involved setting up an experimental pump and test facility to obtain input – output data under typical operating conditions. The experimental data was used to first train the dynamic neural network and subsequently the static compensating neural network. The results were considered to be acceptable for modeling purposes and it was concluded that the combination of a Dynamic Neural Network and a Static Neural Network could be used to capture the steady state and dynamic characteristics of a load sensing pump over a wide range of operating conditions.
Experimental Study on the Wear Characteristics of Polyetheretherketone (PEEK) Slipper with Different Swashplates under High Load and High Speed
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Qunguo and X. Donghu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 416-419,
April 2005
view abstract
Friction and wear is one of the most difficult problems that must be tackled properly in the research and development of tap water or sea water hydraulic power transmission and control technology, owing to the strong corrosion and insufficient lubricity of pure water in contrast with mineral oil. Materials that demonstrate excellent anti-wear property can not applied to water hydraulic components since those materials, which in general are carbon steel, aluminium or copper alloys, cannot resist the corrosion by water, especially seawater. Therefore, much attention must be paid to the selection of appropriate materials that can meet the special requirements of the components such as slipper, swashplate, and cylinder bore or lining, flow distribution plate, etc. Since there are quite few experimental results available that can be consulted, some fundamental test should be carried out before some certain materials are adopted in design. Simple comparison of the physical and mechanical properties of some engineering plastics shows that polyetheretherketone, abbreviated as PEEK, possesses superior comprehensive properties such as high stiffness and hardness, low water absorption ratio, prominent anti-wear capability and chemical stability. There is no denying that PEEK is one of the most important candidate materials for frictional components. In this paper, on the test rig that simulates the interaction between slipper and swashplate, piston and cylinder, the tribological features of PEEK as slipper and cylinder bore lining materials were tested. Some detailed experimental results are presented, and further explanation is given with the aid of microstructure analysis of the worn surfaces. The swashplate material includes 2Cr13 which was heat treated, stainless steel whose surface is modified by plasma sprayed ZrO2MgO and laser melted alloy respectively. It is found that the wear of PEEK is the least when its counterpart is laser-melted alloy, and the wear is most when its counterpart is plasma sprayed ZrO2MgO.
Experimental Validation of Mathematical Models of Hydraulic Pipelines with High-Frequency Excitation
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2000
B. Manhartsgruber,
Professional Engineering Publishing,
ed. C.R. Burrows and K.A. Edge,
2000,
pp. 29-42,
September 2000
view abstract
Laminar pipe flow of compressible fluids has been studied by numerous authors in the past. While the one-dimensional wave equation was sufficient for the early work on wave-propagation and waterhammer, the second order effects of viscosity, heat-transfer, etc. were introduced in the early 1930s. This two-dimensional theory leads to the concept of frequency-dependent friction which is crucial for the simulation of fluid power transmission lines. The aim of this paper is to provide reliable experimental results of a hydraulic pipeline using a test rig with simple boundary conditions and a rigid mounting of the pipe.
Experimental Validation of Pipeline Models for Laminar and Turbulent Transient Flow
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
S. E. M. Taylor and D. K. Longmore and D. N. Johnston,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 99-104,
November 1997
view abstract
Work has been carried out on the time domain simulation of hydraulic pipelines. A new method of approximating frequency dependent friction has been developed (Sanada et al., 1993). The new optimised friction model has been incorporated into time domain simulation models. The results are validated by experimental tests. Transient test rigs have been designed for both laminar and turbulent flows. In both cases the levels of damping shown by the simulations corresponded favourably to the experimental results obtained.
Experimental Validation of Theoretical and Numerical Models of a DDV Linear Force Motor
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. Rito,
2004,
pp. 105-114,
Juni 2004
view abstract
The performances of a Direct Drive Valve (DDV) mainly depend on the characteristics of its Linear
Force Motor (LFM) and the availability of accurate models of the LFM plays an important role in the
whole actuation system design. The present work deals with the modelling and the experimental
characterisation of a LFM. By means of a specifically designed test equipment, the force provided by the
LFM of an off-the-shelf DDV is measured as a function of the coil current and of the spool position. The
experimental data are compared with the results of two models: a theoretical one, based on the magnetic
circuit theory, and a numerical one, based on the FEM analysis of the electromagnetic components of the
system. The numerical model provided good results over a wide range of test conditions and it allowed to
evaluate correction factors for the theoretical model, related to the presence of secondary paths in the
magnetic fluxes and to the distortion of the magnetic flux lines.
Experiment Demonstrating of Oil contamination On-line Monitoring System Based on the Filter Membrane and Fill-Up Method Theory
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Qisheng and Z. Jingyi and T. Hao and L. Kan,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 632-636,
April 2005
view abstract
The paper had dissertated the beforehand debugging experiment of oil contamination on-line monitoring system, demarcating experiment using standard contamination level oil. The fact contamination oil on-line monitoring experiment had been done, which had validated the system characters of feasibility, reliability, advantage, etc.
Experimenting with Electrical Load Sensing on a Backhoe Loader
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. O. Andersen and M. R. Hansen and H. C. Pedersen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 171-175,
April 2005
view abstract
Where traditional load sensing is made using hydro-mechanical regulators and load pressure is fed back hydraulically, electrical load sensing employs the usage of electronic sensors and electrically actuated components. This brings forth new possibilities, but also imposes problems concerning dynamic performance and stability.
In this paper the possibilities for implementing electrical load sensing (ELS) on a backhoe loader is investigated. Major components in the system are modelled and verified, and a linear model of the pump is presented, which is used for designing the pump controller. By comparing results from linear analyses performed on both the conventional hydraulic load sensing system (HLS) and the modified electrical load sensing system, it is concluded that system performance closely matching the conventional system is obtainable.
Exploitation of Hydraulic Multifunctional Testing System Based on VC++
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. Kan and X. Kong and Y. Gao,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 754-758,
April 2005
view abstract
The article points out the problems of the traditional methods in testing the existed hydraulic assembled and unassembled test bed, advances the plan of using the technology of modern sensor, the technology of data acquisition and the program computer control to realize a hydraulic multifunctional testing system. Based on the QCS014A a test bed that can be assembled and unassembled, VC++ control program, makes a testing system.
Fast Actuation of Hydraulic Switching Valve by Parametrically Excited Structures
Proceedings of the 6th UK Mechatronics Forum Conference (Mechatronics '98), Skövde, Sweden
M. Garstenauer and R. Scheidl,
1998,
pp. 477-482,
September 1998
view abstract
The mathematical model and several design ideas for a new type of hydraulic switching valve are presented. Design goals are extremely high switching frequencies (in the order of 1 kHz), and robust and simple mechanical components and control electronics. The actual flow control element is driven by a parametrically excited elastic structure, in this case a beam. A method that allows an appropriate design of this beam is developed. A first prototype with hydraulic force control was built and its set-up is presented. Several design ideas for future, high speed versions are discussed focusing on piezoceramic actuators, the elastic structure, and the flow control element as key components.
Fast Development and Rapid Prototyping of a Compact Fast 3/2 Way Switching Valve
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
A. Plöckinger and R. Scheidl and B. Winkler,
2008,
pp. 137-143,
September 2008
view abstract
A fast 3/2 way solenoid actuated spool type switching valve and its fast development and rapid prototyping are presented. The valve features a very compact design for ease of integration, a nominal flow rate of 10 l/min @ 5 bar pressure loss, a switching time of approximately 1 ms, a powerful yet compact solenoid, and an integrated wave spring for spool actuation.
The valve’s switching performance, in particular the magnetic force characteristics, were studied by extensive simulations. For a first feasibility check of the design, the valve was manufactured in ABS (Acrylnitril-Butadien-Styrol) by a 3D printer. To check the achievable switching time, the spool was manufactured in steel and the magnet as a laminated stack with a copper winding. The other valve components, however, were taken from the 3D printer plastic realization. First tests confirmed the concept, but showed that a somewhat larger magnet is required to achieve the intended short switching times.
Fast Hydraulic Switching Valves - Key Components for the Introduction of Switching Techniques in Oil Hydraulic Drives
Proceedings of the 3rd International Heinz Nixdorf Symposium on Mechatronic and Advanced Motion Control, Paderborn, Germany
M. Garstenauer and R. Scheidl,
1999,
pp. 281-294,
Mai 1999
view abstract
Mechatronic systems designers demand compact, high speed, high power and energy efficient actuators for their products. Hydraulics offers many of these properties, but what is missing are control concepts that achieve high dynamics and high energy efficiency at reasonable system costs. The two dominant basic hydraulic control concepts are compared and both concepts show significant weaknesses. Switching type power converters, which are well known in power electronics, show promising features to implement these demands. A new converter type, the so called resonance converter, is investigated both analytically and experimentally. Key component for the commercial implementation of switching type converters are high speed valves. A new valve design well suited decrease switching times by a factor of one hundred compared to existing valves is proposed.
Fast Pointing Control for Systems With Stick-Slip Friction
Ruh-Hua Wu and Pi-Cheng Tung,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 614-626,
September 2004
view abstract
A controller consisting of three schemes, one proportional gain, one pulse, and one ramp, is proposed to achieve precise and fast pointing control under the presence of stick-slip friction. Design of the controller is based on two distinctive features of friction, the varying sticking force and presliding displacement of contacts under static friction. The latter is the main idea behind the ramp scheme to accomplish the fast pointing task. Implementation of this multistage control strategy requires position measurement only. Experimental results demonstrate the effectiveness of the proposed controller for the desired performance.
Fault Classification Based on Self−Organizing Maps in Water Hydraulic Forklift
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
T. Krogerus and H. Sairiala and H. Riipinen and M. Saarinen and K. T. Koskinen,
2007,
volume 1,
pp. 61-76,
Mai 2007
view abstract
The goal of this paper is to study typical fault situations from water hydraulic valves and cylinders where the Self-Organizing Maps (SOM) with unsupervised learning is used to classify measurement data. Before classification feature extraction is performed to extract relevant and discriminating information from the measurement data and also to reduce data dimensionality. This way it is possible to reduce the amount of measurement data points and improve their interpretability. The extracted features are then used for training and testing the SOM. Feature extraction method used in this paper is wavelet analysis. Operation of the fault classifier is tested in a test system of water hydraulic forklift where the lift movement from the forklift is used.
Fault Detection And Diagnosis of Digital Hydraulic Valve System
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
L. Siivonen and M. Linjama and M. Huova and M. Vilenius,
2007,
volume 1,
pp. 211-226,
Mai 2007
view abstract
Fault detection and fault diagnosis is the key into fault tolerance of components. Interest on this area has increased a lot lately when measurement systems have developed and
hydraulic systems have gotten more complex. Although reacting into faults has not been studied so much, research on fault adaptive systems has increased a lot also. The limitation for this has so far been the lack of components that are capable of operation in case of a failure. Previously only possible solution has been doubling of components but in practice this has been used only in extreme applications. Digital hydraulics has some good features concerning fault tolerance. The system is capable for acting in fault situation with only a small degradation in performance without having to add expensive
and troublesome extra components into he hydraulic circuit. This paper concentrates on detecting different kind of valve faults and reacting into them by re-configuring the
controller. The fault detection is done by using control electronics internal diagnostics signals and by measuring voltage differences over the valve coils. The signals are
diagnosed and the control code is then re-configured according to the fault. The detection and reacting into faults is done on-line and the results show that the system is capable of acting without significant degradation in performance even if rather severe faults occur.
Fault Detection of Simulated Servo Hydraulic System by Utilizing Artificial Neural Network (ANN)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
M. Riahi and H. Gholizadeh,
2006,
pp. 229-237,
Mai 2006
view abstract
Maintenance reliability and efficiency in industrial hydraulic systems operation has
become a point of concern for the professionals in maintenance engineering. One practical
approach in this regard is the realization of symptoms of early stage malfunctioning in fluid
power systems after which maintenance planning and preventive means would follow upon a
reasonably accurate and subsequently acceptable determination. Among the highly reliable
sources providing such convenience, Artificial Neural Network (ANN) stands a high chance of
success.
Neural network method has been used to detect faults occurring in most hydraulic systems.
These faults could be related to supply pressure, effective bulk modulus and total leakage. The
simulated system in this study consists of hydraulic servo valve, double acting cylinder and a
spring that resists piston movement. Two main reasons causing this system to have a nonlinear
behavior are hydraulic servo valve and compressibility effect of hydraulic fluid.
The neural network approach in this investigation comprises of an efficient use in nonlinear
systems and requires advance knowledge about the system behavior under faulty conditions and
assumptions about the type and severity of faults likely to occur. Neural networks trained with
different training algorithms are investigated. After training the network, the system was
examined for different inputs and obtained results were compared.
Fault Diagnosis of a Pneumatic Subsystem
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
R. Gutiérrez González and J. Bredau and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 537-548,
März 2010
view abstract
Condition monitoring and diagnostics of fluid power systems are trend topics. The benefit of their implementation is an increase in the availability of machines and systems because of the fast detection of faults. This paper presents different approaches for fault diagnosis of a pneumatic valve-actuator unit by the use of regular sensors in pneumatics. Several approaches with different diagnosis depth, or level of detail, will be proposed and compared.
Fault diagnosis of pneumatic systems
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
S. Fritz and H. Murrenhoff,
2007,
pp. 27-40,
September 2007
view abstract
Online-diagnosis can help to avoid costs by predictable maintenance, using the full lifespan of the pneumatic elements and easy-to-use localization of faults in complex systems in case of damage. Starting from an industrial application –a welding gun of an automobile manufacturer’s welding facility– the paper will show the main forms of wear and their consequences to the pneumatic process. These faults are integrated into a simulation model of the whole pneumatic system based on the DSHplus simulation tool for fluid power systems. Mathematical functions use only the present sensor signals of the system control in specific time ranges and yield so-called features for the fault diagnosis. Classification of these calculated features to faults is done by a weighted feature-fault matrix.
FAULT TOLERANCE OF DIGITAL HYDRAULIC VALVE SYSTEM WITH SEPARATELY CONTROLLED FLOW PATHS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13-17, 2006
ISBN: 1-4243-0500-4,
L. Siivonen and M. Linjama and M. Vilenius,
2006,
volume 2,
pp. 331-343,
Juni 2006
view abstract
Fault tolerance is desired in applications, where stopping or inappropriate acting of the system may cause time and
financial losses, may damage the machine itself or the surroundings, or where even lives are in jeopardy. In hydraulics, where human-machine interface, good power density, fast movements and big masses usually exist, the effect of fault tolerance emphasizes. Digital hydraulic valve system is a proportionally acting direction flow control valve capable for
controlling hydraulic actuators accurately. The valve system is also fault-tolerant and tests showed that if faults are
detected and the re-configuration of the controller is done properly the system is capable for continuing operation
without significant degradation in performance.
Filter and Particle Simulation for Hydraulic Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
K. Wartlick and R. von Dombrowski and A. Schindelin,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 579-591,
März 2010
view abstract
Within the German government-funded research project “Fluidtronic” a commercial system simulation tool for hydraulic systems has been set up for particle simulation. Models for particle transport, particle entrainment and filtration have been developed and implemented. This offers the possibility to simulate the dynamic distribution of particles also in more complex hydraulic systems. It allows efficient filtration design and enables to check the purity levels of sensitive components, such as servo valves. Other advantages are the better planning of maintenance intervals and the possibility to have a look at different operating conditions, e.g. cold starting conditions in mobile hydraulic systems. In this paper, the models for particle and filter simulation are described. Furthermore, first simulations and verifications are shown.
FINITE ELEMENT MODELING AND SIMULATION OF A MAGNETORHEOLOGICAL (MR) VALVE
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
J. Kostamo and J. Kajaste,
2006, August 2006
view abstract
The rheological properties of magnetorheological fluids can be varied by application of a magnetic field. This feature provides interesting possibilities to design novel hydraulic systems. The need of zero moving parts for the valve function makes it possible to construct compact systems with minimum fatigue. MR fluids have been successfully used in shock absorbers for automobiles and other semi-active vibration control tasks.
The device presented in this paper is a cylinder formed valve in which the fluid flows through two annular gaps. The main parts of the actuator are the iron core, the flux return and the coil. In the annular fluid gaps that are formed between the iron core and the flux return, the magnitude of the magnetic field can be controlled by altering the coil current. These control edges replace the traditional orifices and spindles of normal hydraulic valves.
The aim of this research work is to evaluate the performance of MR valve. The finite element modelling process of a MR valve will be presented and various aspects related to magnetic and hydraulic circuit design are considered. The coupled phenomenon between the magnetic circuit and the MR fluid flow will be analyzed and guidelines to design high efficiency MR valves are given. Also future work in the valve development and relations to ongoing projects are briefly introduced.
FLATNESS BASED CONTROL OF A FAST SWITCHING HYDRAULIC DRIVE
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
H. Kogler and B. Winkler and R. Scheidl,
2006, August 2006
view abstract
Hydraulic switching control attempts to transfer concepts from modern electrical drive control to hydraulics. Both,
electrical and hydraulic switching systems allow to increase the efficiency of such drives. But it is more difficult to
realise hydraulic than electrical converter principles. Especially wave propagation in the hydraulic fluid is a serious
problem for the modelling. For evaluating control strategies one needs a compact mathematical model of wave
propagation, preferably of lumped parameter type. In this paper, the flatness based control of the hydraulic equivalent
of the electrical ‘Buck Converter’ is studied. Basically the converter consists, like its electrical pendant, of a hydraulic
inductivity and a hydraulic accumulator for pressure attenuation. The load is realised by a hydraulic cylinder with a
mass and a corresponding dead load. In contrast to the electronic converter the dynamic behaviour of the hydraulic
‘Buck Conveter’ treated here is nonlinear, because of the valve characteristics, the gas spring of the accumulator, and
the variable hydraulic capacity of the piston sided chamber of the cylinder. Furthermore, it is important to avoid
cavitation. Because of the switching the system is discontinuous. To obtain a continuous model, which is essential for
control strategies which rely on a continuous system, averaging of the two systems states into one averaged system
must be performed. Furthermore, the properties of the system allow to observe several states of the system. A properly
designed hydraulic switching drive in combination with a flatness based controller can achieve excellent performance,
satisfactory accuracy, and increased efficiency.
Flexible Pneumatic Actuators for Underwater Robot
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Costamagna and M. Carello and C. Ferraresi and A. M. Bertetto,
2004,
pp. 59-66,
Juni 2004
view abstract
At the Department of Mechanics of the Technical University of Turin (Politecnico di Torino)
a research work has been started, aimed at realising an underwater robot propelled by an
oscillating fin actuated by a flexible actuator. In this frame, several prototypes of flexible fluid
actuators have been designed and realised. All the prototypes have a deformable elastomeric
structure moved by a pressurised fluid supplied in two internal chambers. This type of
actuator appears very suitable to produce a fish-like propulsion, since it is able to take a
biomorphic shape, similar to those of natural fishes.
The paper describes the design methodologies and the technical details adopted to realise the
actuators. Then it describes the way the actuators have been characterised and the special
equipment realised to this aim. Finally two different kind of actuators, one with a cylindrical
geometry and one with a more biomorphic conical shape, have been tested in water in order to
measure the thrust force. The results show a much better effectiveness of the biomorphic
actuator.
Flow Analysis and Modeling of Shock Absorbers
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
F. Herr and T. Mallin and J. Lane and S. Roth,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 69-75,
November 1998
view abstract
A Computational Fluid Dynamics (CFD) method, combined with a dynamic modeling technique were introduced to study the flow and performance of automotive hydraulic damper / shock absorbers. The flow characteristics of component obtained by using CFD was applied to dynamic modeling package to predict the damping force. The component CFD analysis showed unique features as far as flow part tern, discharge coefficients and pressure distribution for various shock absorber components. Dynamic damper model was constructed by using a commercial package Easy5 with flow information provided by CFD. A simple representation of the complicated design of shocks as a network of fixed and variable restrictions in series and parallel connected by compliant volumes of oil is suitable for capturing the dynamics important to vehicle handling simulations.
Flow Analysis in Control Valve Using a Vortex Method
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
T. Tsukiji,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 59-67,
November 2003
view abstract
In the present paper, the formulation of the vortex method combined with the boundary element method is described. The three dimensional compressible turbulent flow including moving boundary problems can be solved using the method in the application of the fluid power with the oil hydraulics and the pneumatics. The effect of the compressibility is considered by the distributions of the fluid elements with the dilatation. The viscous diffusion effects and the no-slip condition are considered. The present method is a grid-free and Lagrangian field method in which the physical quantities are transported along the fluid particle trajectories. As one of the examples of the applications the two dimensional numerical analysis in the oil hydraulic ball valve is conducted. The calculated results proved that the present vortex method is very useful in analyzing the turbulent jet flow issuing from the orifice of oil hydraulic ball valve during the vibration of the ball.
Flow characteristics measurement of large valves
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
B. Manhartsgruber and B. Winkler,
2007,
pp. 449-458,
September 2007
view abstract
The functional relationship between the flow rate through a hydraulic resistance and the occuring pressure drop is fundamental for the design and analysis of fluid power systems. In the case of valves, a standardized procedure for the measurement of the flow rate vs. pressure drop characteristics is given in ISO 4411. However, the test rig for an experiment according to this standard is quite expensive in the case of large valves. The largest commercially available cartridge valves have a flow capacity of 25000 L/min. In order to measure their flow characteristics according to ISO 4411, the test rig has to deliver this flow rate over some period of time. The second problem is the cost for a flow meter of this size. Typically, valve test rigs are only available up to flow rates of a few hundred litres per minute. If the flow capability of the valve to be tested is in the thousands of litres per minute, valves can often only be tested in the application but not in a laboratory.
This paper describes a new approach for the measurement of the flow characteristics of large valves by the use of a pressurized column of oil in a pipeline. During an opening instant of the device under test, several pressure signals are recorded and used for an analysis based on the Joukowsky relation between pressure and flow rate. This valve opening experiment can be repeated at different pressure levels resulting in a pointwise determination of the pressure drop vs. flow rate function. The method has experimentally been checked against the conventional flow-meter approach with a cartridge valve of nominal size 16 mm at flow rates up to 150 l/min. A large scale test rig for flow rates up to 4000 l/min is under consideration.
Flow Characteristics of Pressurized-Water in Annular Micro-Clearance
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Zirong and L. Xibing and L. Yingchun and Z. Shulin,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 184-188,
April 2005
view abstract
The flowrate of pressurized-fluid in annular micro-clearance between the piston and cylinder will seriously affect the efficiency of plunger pumps and hydraulic motors. The discharge not only depends on the shape of clearance and pressure, but also on the flow state. In engineering fluid mechanics, the flow state of oil used as transmitting medium of power is laminar flow, but when water is used as transmitting medium, because of its very low viscosity, whether the flowing state of pressurized-water in annular clearance can still be considered as laminar flow? So far, there is no any paper describing it clearly. The relation between the flowrate and Reynolds number in annular clearance is analysed theoretically and a role is obtained that when the diameter of plunger is fixed, the critical flowrate between laminar and turbulence only depends on fluid' property (viscosity). In order to explore flow characteristics of pressurized-water in different condition, a self-designed and self-made experimental device and experimental scheme are introduced which is used to measure flowrate of water. The experimental data that water in 4~15 MPa pressure flows through the clearance of 0.005~0.05mm and seal length of 2~40mm is introduced and analysed, and is compared with theory flowrate of laminar flow. The results show that limit flowrate of pressurized-water through different cylinder to piston clearance is constant when other conditions do not change and the condition of laminar flow of water in annular clearance is clearance value <0.01 and the pressure <6.3MPa and when the clearance value >0.02mm and the pressure >8.0MPa, laminar flow will change into turbulent flow .In engineering application, the clearance value cannot be too small (generally >0.002) and flow pressure of hydraulic equipment is usually larger than 8.0MPa, so the flow of water in annular clearance will be turbulent flow. The
research will offer a theoretical foundation for the design and manufacture of water hydraulic component.
Flow Characteristics of the Piezoelectric Driven Pneumatic Valve for Grain Sorter
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Yun, So-Nam and Yun, Dong-Won and Kim, Hong-Hee,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 273-283,
März 2010
view abstract
The most important parameters for desinging the grain sorter valve are the larger actuator displacement, the more flow rate and the lower energy comsumption, and many kinds of actuator such as solenoid method, stack type piezoelectric method and multilayered bender type PZT method are being studied and discussed.
This paper presents the new mechansm for the grain sorter and discusses the flow characteristics of the piezoelectric driven pneumatic valve which has a multilayered peizoelectric actuator and two ports for air flow. In order to design the piezoelectric driven pneumatic valve, the flow dynamics are analyzed theoretically and the processes for fabrication of the multilayered piezoelectric actuator are researched. Finally, pneumatic valve with a multilayered piezoelectric actuator is manufactured, and the characteristics of the displacement and blocking force of the piezoelectric actuator and the flow capability of the manufactured pneumatic valve are also experimentally discussed.
Flow Control Concept of Submerged Ballast Pumps with Hydraulic Drive Supplied from Hydraulic Central Loading System on Modern Product and Chemical Tankers
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
A. Banaszek,
2010,
volume 2,
pp. 643-656,
Juni 2010
view abstract
The flow control concept of submerged ballast pumps, supplied from hydraulic central loading system on modern
product and chemical tankers is presented in the paper. The possibility of use hydraulic central loading system for
powering of ballast pumps is shown. The structure of submerged ballast pump with hydraulic drive together with
description of hydraulic system mounted on board of modern product tanker is given. Main methods of flow control of
submerged ballast pumps together with new idea with use of constant-torque controllers are given. The advantages of
such solution have been pointed out. Experimental results of constant-torque controller researches are presented.
Flow Controlled Variable Displacement Hydraulic Motors for Highly Efficient Aircraft Actuation Systems
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
Giovanni Jacazio,
2007,
volume 1,
pp. 153-166,
Mai 2007
view abstract
This paper first presents a brief outline of the general characteristics of hydraulic actuation systems based on variable displacement hydraulic motors (VDHMs), then it describes
the architecture of an innovative solution proposed for the actuation of the cargo door of an aircraft for which a control technique was developed to further exploit the advantages of such hydraulic motors. The merits of this solution are outlined and a
comparison is made with the performance of a conventional system using fixed displacement hydraulic motors.
Flow Field in a Pipe with Sudden Expansion by FEM Method
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
D. Gao and L. Yang and G. Hou,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 443-447,
April 2005
view abstract
In this paper, the finite element method (EM) was used to discrete the continuity equation and the equation of stream-function(ψ)-vorticity(ω), The flow field in a sudden expansion with different Reynolds number and with different expansion ratios has been simulated. The vortices in the comer of the step was presented by the streamline and velocity profiles. Comparison of the flow field between different Reynolds numbers and expansion ratios are also demonstrated. The results show that the greater the expansion ratio is, the larger the vortices are. The greater the Reynolds number is, the more intensity of the vortices is. The study has significance for designing the pipe systems with sudden expansion to minimize the energy loss.
FLOW FORCES ANALYSIS ON A FOUR-WAY VALVE
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
G. Del Vescovo and A. Lippolis,
2002, Juli 2002
view abstract
The aim of the present paper is the analysis of the flow inside proportional directional valves; in particular a four way
valve with tetrahedral notches, the most widespread in commercial valves, is considered. The flow analysis has been
carried out using the “Fluent” code on appropriate computational grids designed by means of “Gambit”, after a detailed preliminary analysis of local grid refinements. The influence of spool opening sections is analysed; pressure and
velocity contours and global non-dimensional parameters have been used to better underline the performed results.
Finally, a detailed study of employed turbulence model, an analysis of the spool angular position and of a suggested
simplified computational model is reported.
Flow mass monitoring of potato harvest on laboratory conditions
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
P. Heřmánek and J. Mašek and P. Procházka,
2006,
pp. 89-94,
Mai 2006
view abstract
Precizní zemědělství představuje proces hospodaření na pozemku podle lokálních
podmínek a vlastností daného pozemku s optimalizací nasazení produkčních faktorů. Hlavním
cílem tohoto systému je snaha přizpůsobit dané operace lokálním podmínkám pozemku. Při
sklizni brambor je na strojích stále nevyřešena problematika sledování průchodnosti
materiálu. Příspěvek uvádí jednu z možností sledování průchodnosti brambor při jejich
sklizni. V příspěvku je uveden postup návrhu hydraulického mechanismu pro pohon
prutového prosévacího dopravníku, který se používá na sklízečích brambor. Příspěvek
obsahuje metodiku měření výkonových parametrů hydraulického obvodu pohonu dopravníku
a výsledky měření v podobě grafu.
Flow pulsation reduction for variable displacement motors using cross-angle
Power Transmission and Motion Control 2007, Bath, UK, 12-14 Septembre 2007
ISBN: ISBN 978-0-86197-140-4,
L. Ericson and J. Ölvander and J-O. Palmberg,
2007,
pp. 103-116,
September 2007
view abstract
Sammanfattning/Abstract: This paper considers using the cross-angle in variable displacement hydraulic machines. The cross-angle is a fixed displacement angle around the axis perpendicular to the normal displacement direction. The cross-angle changes the angles to the pistons top and bottom dead centres as a function of the fraction of displacement in such a way that the valve plate timing is varied and different pre-compression and decompression angles are obtained.
A non-gradient optimisation technique, the Complex method, is used together with a comprehensive simulation model in order to find the optimal cross-angle for a variable displacement hydraulic motor. The paper shows that the cross-angle can be used to reduce noise in variable displacement motors. One issue that makes the motor application more difficult is the increased dependence between outlet and inlet flow ripple which is not found in pump applications. Furthermore, the paper discusses how to use the cross-angle for machines which can work both as a motor and a pump.
Flow pulsation reduction for variable displacement motors using cross-angle
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
L. Ericson and J. Ölvander and J.-O. Palmberg,
2007,
pp. 103-116,
September 2007
view abstract
This paper considers using the cross-angle in variable displacement hydraulic machines. The cross-angle is a fixed displacement angle around the axis perpendicular to the normal displacement direction. The cross-angle changes the angles to the pistons top and bottom dead centres as a function of the fraction of displacement in such a way that the valve plate timing is varied and different pre-compression and decompression angles are obtained.
A non-gradient optimisation technique, the Complex method, is used together with a comprehensive simulation model in order to find the optimal cross-angle for a variable displacement hydraulic motor. The paper shows that the cross-angle can be used to reduce noise in variable displacement motors. One issue that makes the motor application more difficult is the increased dependence between outlet and inlet flow ripple which is not found in pump applications. Furthermore, the paper discusses how to use the cross-angle for machines which can work both as a motor and a pump.
Flow ripple reduction in power steering hydraulic pumps
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
L. Z. Rocha and N. Johnston and S. Gerges,
2010,
pp. 187-200,
September 2010
view abstract
Noise in hydraulic power steering systems is mainly generated by the hydraulic pump due to the cyclic pumping mechanism that creates pulsating flow transmitted by the fluid. This flow ripple and pressure ripple, propagating through the hydraulic circuit, interacts in a complex way with the other parts of the vehicle, generating audible noise inside the Vehicle.
The present work shows two ways to reduce the flow ripple amplitude generated by a vane pump through the redesigning of the pump rotating group. First, a nine-vane rotor pump is proposed and, secondly, a pump with three discharge ports is proposed. To check their results, a MatLab/Simulink based pump model was created according to the new geometrical characteristics and the results are compared with the regular pump ones. Also, a flow ripple experimental test was run using the Secondary Source Method to validate the numerical model results of the regular pump. The new designs simulation results show large flow ripple amplitude reduction (from 6dB to 16dB per harmonic) as well as frequency displacement in the discharge flow ripple spectra in both designs. Also, the simulations show perpendicular force on the pump shaft generated by the non-balanced conditions created by the new designs.
Fluid Aeration as an Essential Problem in Modelling of Hydraulic Systems
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
J. Pobedza,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 227-257,
view abstract
No abstract available
FLUID BORNE NOISE CHARACTERISTICS OF A GEROTOR PUMP MEASUREMENT AND PREDICTION
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
P.J. Gamez-Montero and E. Codina Macia,
2002, Juli 2002
view abstract
The aim of this paper is to document a better understanding of the performance of crankshaft mounted gerotor
pump for IC engines lubrication. Intense measurement techniques in the testing phase, at steady-state conditions,
were required in order to enhance the BondGraph model and an improved comprehension of this type of volumetric
pump was dedicated to obtain the flow ripple characteristic of this unit of gerotor pump through the secondary
source method. This study has been carried out on two different test rigs with its own instrumentation and analysis
which were implemented to reach a comparison of the results for the same unit. At a different extent, the modelling
and simulation phase to describe a mathematical approach of the geometry and kinematics flow ripple has been
considered by using BondGraph method.
FLUID DYNAMIC BEHAVIOUR OF AN INTERNAL ROTARY PUMP GENERATED BY TROCHOIDAL PROFILES
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
P. J. Gamez-Montero and E. Codina Macià,
2000,
pp. 33-47,
September 2000
view abstract
In this paper we would like to present the current state of analysis and work on the activities carry out in the first
year of our studies. The aim of these activities was to study the suction performance of the Gerotor pumps and it
is influence on the fluid-borne noise generated. This work is presented in three levels: geometry, simulation and
experimentation. The geometric study allows us to penetrate the knowledge of the trochoidal profiles and assists
in the optimisation of them. The different methods of calculation and the simulations allow us to evaluate the
fluid-dynamic performances and the influence of the input and output impedance. We would like to emphasize
the exhaustive use of Bond Graph simulations. In the last level, the models have to contrast experimentally with
the test benches that are described in this paper.
Fluid Dynamics − Comparison and Discussion on System−Related Differences
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
J.−P. Karjalainen and R. Karjalainen and K. Huhtala and M. Vilenius,
2007,
volume 2,
pp. 371-381,
Mai 2007
view abstract
The dynamics of hydraulic fluid is an important factor when dealing with systems demanding increasingly higher accuracy and performance. The most important dynamic fluid parameters are bulk modulus, density and speed of sound in a fluid which can be measured in several reported ways. Usually the main interest is to find out the adiabatic bulk modulus which can be determined along with density by measuring the speed of sound in the fluid.
In this paper the measured dynamic parameters of selected commercial hydraulic fluids are compared. The parameters were measured using two alternative but theoretically similar systems. The systems are also compared to an ISO standardized method, the results of which are to be reported later. The measurements are also compared to simulations. Finally, all the results are concluded for discussing the fluid dynamics in some typical hydraulic systems.
Fluid Power Actuators for Structural Control - An Overview
Proceedings of the Third European Conference on Structural Control, Vienna, Austria
R. Scheidl,
2004,
volume 1,
pp. M8-5 - M8-8,
Juli 2004
view abstract
Fluid power actuators have performance characteristics that make them best solutions for several structural control applications. Various types are compared with respect to their performance characteristics. A simple truss/beam model is set-up to assess the appropriateness of fluid power actuators and compare them with piezoelectric actuators. Non functional criteria are discussed and the potential of hydraulic switching control is highlighted.
Fluid Power - a Way Forward
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
J. Stecki,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 37-65,
view abstract
No abstract availalbe
FLUID POWER CONTROL UNIT USING ELECTRORHEOLOGICAL FLUIDS
K. Wei and G. Meng and S. Zhu,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 49-54,
November 2004
view abstract
Electrorheological (ER) fluids can change their rheological properties when subjected to an electrical field. By using
ER fluids as the working medium in fluid power systems, direct interface can be realized between electric signals and
fluid power without the need for mechanical moving parts in fluid control unit. The pressure drop and flow rate can be
directly controlled through the change of applied electric fields. This paper investigates the design and controllability of ER fluid power control system for large flows. The design criterion for an ER valve is proposed and four ER valves are
manufactured based on this criterion. A fluid control unit consisting of an ER valves bridge circuit is constructed, the
characteristics of which are theoretically and experimentally investigated. The results show that the ER fluid control
units have better controllability for fluid power control.
Fluid Power Systems and Mechatronics (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
P. Noskievič,
2006,
pp. 15-29,
Mai 2006
view abstract
Mechatronics and Fluid Power Systems is the topic o this paper. The mechatronics
and the systematic approach to the design of the mechatronic system based on the V-model
introduced in the guideline VDI 2206 is presented in the first part of the paper. The fluid
power systems as mechatronic systems can be dividend in three groups: components of the
pneumatic and hydraulic circuits, closed loop controlled drives – pneumatic and hydraulic
axis, production machines and equipments with hydraulic drives and hydraulic systems in
mobile industry.
The mathematical modelling and simulation have important role by the design of the
mechatronic systems. Simulation model allows obtain the dynamic properties of the designed
systems before the prototype is realized. In this fact the development costs can be lower, the
development process can run faster and consume less time. The simulation software suitable
for modelling and simulation of the hydraulic and pneumatic systems in connection with
mechanical and control systems is introduced in the next part of the paper. The simulation of
the pneumatic servomechanism is presented using the simulation programme AMESim and
the technical realization is shown based on the FESTO components. The mechatronic
approach is shown on the control of the linear hydraulic cylinder in the vertical position with
the pulling external force. The classical solution with the control valve with four control
edges and symmetric spool is replaced by the control using two control valves instead of
spool with different flow gain for port A and B. The control algorithm takes into the account
the different cross section area of the piston of the cylinder. This solution allows also
realization of other control algorithm and other control tasks – pressure and force control.
The paper summarizes the mechatronic approach by the design of the complex structure
systems with the emphasis on the system simulation.
Fluid Power Systems in Downhole Seismic Exploration
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
J. H. Cole,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 199-203,
November 1997
view abstract
High-resolution subsurface seismic imaging that places sources and receivers in wellbores is an exploration technology that can help petroleum companies find and recover more oil and gas. Success-commercialization of this enabling technology requires the development of stronger downhole seismic sources. New and larger downhole fluid power systems are playing a major role in such development. An extensive R&D effort has produced an electrohydraulic vertical shear wave source that is ready for commercial use. Research is continuing on other fluid power source concepts.
Fluid Power Technology - Progress or Plateau?
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. R. Burrows,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 16-25,
April 2005
view abstract
*No Abstract available!
1st break of 1. Introduction following:
In the UK, the Chancellor of the Exchequer continuously stresses the importance of innovation in wealth creation but this is not a new insight (I). The Government recently announced a new five year strategy which calls for a step-change in innovation to meet the challenges posed by international competition.
This paper is not concerned with international competition between fluid power equipment manufacturers, but rather with the competition from alternative forms of power transmission and motion control. This is a global issue: Dempster, the current Chairman of the Board of the American National Fluid
Power Association (NFPA) has noted "Fluid Power is being outsold by electromechanical as the preferred method of motion production and control. You can sum it up by the 'Four C's' - cost, cleanliness, conservation and control". It is therefore important to assess if fluid power technology has reached a plateau or if significant progress is still being made.
Fluid Transmission Line Modeling Using a Variational Method
Jari Mäkinen and Robert Piché and Asko Ellman,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 153-162,
März 2000
view abstract
A variational method is used to derive numerical models for transient flow simulation in fluid transmission lines. These are generalizations of models derived using the more traditional modal method. Three different transient compressible laminar pipe flow models are considered (inviscous, one-dimensional linear viscous, and two-dimensional dissipative viscous flow), and a model for transient turbulent pipe flow is given. The (model) equations in the laminar case are given in the form of a set of constant coefficient ordinary differential equations, and for the turbulent case (model) in the form of a set of nonlinear ordinary differential equations. Explicit equations are given for various end conditions. Attenuation factors, similar to the window functions used in spectral analysis, are used to attenuate Gibbs phenomenon oscillations.
Flux Observer for Spool Displacement Sensing in Self-sensing Push-Pull Solenoids
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
P. Y. Li and Q. Yua,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 772-776,
April 2005
view abstract
Spool position feedback in an electrohydraulic valve typically requires a spool displacement sensing device such as a LVDT. Self-sensing is the methodology to obtain spool displacement information directly from the solenoid spool actuators, thus obviating the additional cost and footprint of a LVDT or another displacement sensing device. A self-sensing scheme that uses only the measurement of electrical signals to the pair of push-pull solenoids was first proposed in [1]. It uses the position dependence of electrical inductance in the solenoids to infer the spool displacement. The scheme in [1] relies on a flux observer and several infinite dimensional filters that require explicit resets, and is prone to singularity. The present paper proposes a modified scheme in which the flux observer (and hence the self-sensing) problem is cast in a linear time varying system setting so that standard linear observer design techniques can be brought to bear.
FMEA MATRIX METHOD IN ANALYSIS OF HYDRAULIC SYSTEMS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
J. Fabiś and E. Lisowski,
2008,
pp. 342-347,
Juli 2008
view abstract
Hydraulic drive and control systems belong to the systems that failure may cause machine malfunctioning or even
putting out of action. To avoid such problems hydraulic components as well as hydraulic systems might be improved to
be more reliable. One of the ways of improvement can be qualitative methods. This paper presents an application of
matrix method of Failure Mode and Effects Analysis (FMEA) for hydraulic system that consists of hydraulic cylinder
supplying by pump with variable delivery. During the FMEA analysis at the beginning two matrixes were created: CF
(Components–Failures) and EC (Functions-Components). To create the CF matrix the investigated hydraulic system
was taken to pieces. Each part of the system was analyzed and assessed in aspect of its participation in system failure.
The table of possible failures that might happen for system components was prepared. Failures were described as three
level system of valuation. Number 2 describes the case when failure exists often, number 1 describes the case when
failure exists seldom while 0 describes case of no failure. The next step was in the FMEA analysis was assignment to
the components functions which they realizing in the system. This allowed creating EC matrix, which similar as CF
matrix was filled up with tree numbers. The last step of the analysis was multiplying the EC matrix by CF matrix. In
results matrix EF (Function Failure) was created. This matrix gives information about probability of failure appearance
for given function. For the FMEA analysis was created own computer software.
Force Balancing Control of Multi- Electro Hydrostatic Actuators for an Aircraft
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J. Li and Y. Fu and B. Gao and Z. Wang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 9-13,
April 2005
view abstract
The parallel driving of two Electro Hydrostatic Actuators will output double power while the cross coupling of' rnulti-EHAs will bring out the extraneous force/torque simultaneity. To eliminate it, we modeled the EHAs with the surface load, derived the extraneous force/torque functions and designed a forcing balancing controller for the innovative EHAs. With the hydraulic load pressure compensation, using the balancing controller, the extraneous force drops from 760.0 N down to 35.0 N when one piston area of the EHAs added 10%.
Force-based impedance control of hydraulic manipulators and its relationship with position-based impedance control
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
A. Muhammad and J. Mattila and M. Siuko and M. Vilenius,
2006,
pp. 291-303,
September 2006
view abstract
The force control of hydraulic manipulators is more challenging than that of electrical manipulators, as electrical actuators are torque sources whereas hydraulic actuators are essentially position/velocity sources. Also, hydraulic actuators behave far more nonlinearly. Hence, Force-Based Impedance Control (FBIC) is far less investigated in comparison to Position-Based Impedance Control (PBIC) for hydraulic manipulators. This paper shows the implementation of FBIC for hydraulic manipulators. Furthermore, a relationship has been established between FBIC and PBIC. It has been shown that equivalent force and position controllers can be obtained for the inner loops of FBIC and PBIC respectively using the established relationship.
Force control at low cost in pneumatic field
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
X. Brun and M. Smaoui and J.-M. Retif and X. F. Lin Shi and E. Bideaux,
2006,
pp. 169-179,
September 2006
view abstract
At the present time in the pneumatic field, when a system requires a wide range of force control, servodistributors are currently used. On/off distributors are used when the system is simpler and only a small range of force values are required [1]. The work presented here consists of using on/off distributors in a system which requires a wide range of force values. This has been carried out in order to reduce the cost of complex systems [2-4], because present day distributors are five to ten times cheaper than servodistributors. This paper presents a new control method applied to the electro-pneumatic field. This strategy originates from the hybrid control theory recently developed for the control of asynchronous or synchronous electrical motors, [5, 6]. This control strategy is an improvement of the proposed one in [4].
Based on both cylinder and distributor models, the hybrid control presented here chooses the best state for each on/off distributor to reach the desired force value. Hybrid control is based on a state space model for both the energy modulator and the continuous sub-process. For this model, a control vector, depending on the number of possible configurations for the energy modulator, is defined. Two formal approaches have been developed for choosing a control vector to track the reference state of interest in the state space. Experimental results are presented and discussed.
Force control for hydraulic load simulator using self-tuning grey predictor - fuzzy PID
D. Q. Truong and K. K. Ahn,
In Mechatronics,
2009,
volume 19,
pp. 233-246,
März 2009
view abstract
Hydraulic systems play an important role in modem industry for the reason that hydraulic actuator systems have many advantages over other technologies with electric motors, as they possess high durability and the ability to produce large forces at high speeds. Therefore, the hydraulic actuator has a wide range of application fields such as hydraulic punching, riveting, pressing machines, and molding technology,
where controlled forces or pressures with high accuracy and fast response are the most significant demands. Consequently, many hybrid actuator models have been developed for studying how to control forces or pressures with best results.
This paper presents a kind of hydraulic load simulator for conducting performance and stability testing related to the force control problem of hydraulic hybrid systems. In the dynamic loading process, perturbation decreases control performance such as stability, frequency response, and loading sensitivity decreasing or bad. In order to improve the control quality of the loading system while eliminating or
reducing the disturbance, a grey prediction model combined with a fuzzy PID controller is suggested. Furthermore,
fuzzy controllers and a tuning algorithm are used to change the grey step size in order to improve the control quality. The grey prediction compensator can improve the system settle time and overshoot problems. Simulations and experiments on the hydraulic load simulator are carried out to evaluate
the effectiveness of the proposed control method when applied to hydraulic systems with various external disturbances encountered in real working conditions.
Force Control Loop Affected by Bounded Uncertainties and Unbounded Inputs for Pneumatic Actuator Systems
Karim Khayati and Pascal Bigras and Louis-A. Dessaint,
In Journal of Dynamic Systems, Measurement, and Control,
2008,
volume 130,
Januar 2008
view abstract
The purpose of this paper is to develop an accurate closed-loop acting force technique for a pneumatic actuator, as an essential stage in the implementation of positioning control strategy. Since an analytical nonlinear structure, which linearly depends on parameter uncertainties, generically characterizes pneumatic plants, a feedback linearization design is proposed to cancel most of the resulting nonlinearities. Then, we proposed a linear state-feedback control and an additive nonlinear action to robustly bound the force error dynamics, devices which are required to handle the further parametric uncertainties and exogenous unbounded disturbances that will arise on the deduced structure. The design of the linear control gains is performed within robust closed-loop pole clustering using a linear matrix inequality approach. Finally, various experimental results illustrate the validity of the approach.
Force control of a roller-screw electromechanical actuator for dynamic loading of aerospace actuators
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
W. Karam and J.-C. Mare,
2008,
pp. 515-528,
September 2008
view abstract
The research work reported in this communication aims to provide key information on the
performance of force controlled roller screw electromechanical actuators (EMA). The first
part introduces the dominant parasitic effects (friction, rotor inertia and test-bench
compliance) that alter both steady state and dynamic open loop performances. The second
part proposes a practical methodology to identify the natural dynamics and to get both
simulation and control models of the EMA without intrusive measurements. The third part
presents the force control of the EMA that is performed through a RST controller, using a
practical step-by-step approach. The controller design is finally validated through multiple
experiments, covering the whole operation domain and proving the control robustness. As a
conclusion, the force control is assessed for a typical requirement corresponding to the
certification of a flight control actuator.
Fork Lift with Free Piston Engine
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
A. Feuser and G. Kunze and A. Mark and A. Winger,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 165-175,
März 2010
view abstract
The further development and proving of a thermo-hydraulic free piston engine (fpe) is the goal to be reached within a common project carried out by the professorship of construction machine and conveying technology at the TU Dresden and Bosch Rexroth AG. The project is supported by the german federal department of economy and technology (BMWi) with reference number 0327247D. One project target is to integrate the fpe into a mobile hydraulic application for demonstration and investigation purposes. Therefore a fork lift of type DFG25BK manufactured and supported by Jungheinrich AG was chosen as a base vehicle. The complete transformation of hydraulic system from common flow to common pressure is accompanied with using a fpe. With this system transformation hydraulic accumulators become applicable. So the known advantages (start-stop-operation, downsizing and recuperation) of hybrid systems can be used to minimize energy consumption and exhaust emissions. The paper introduces the hydraulic hybrid concept designed and describes the buildup of the fork lift.
Formation of Pressure Gain in Hydraulic Servovalves and its Significance in System Behavior
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
A. Ellman and T. Virvalo,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 77-81,
November 1996
view abstract
The pressure gain of hydraulic servovalves is caused by an internal leakage. The leakage flow occurs because of the spool construction and finite radial clearance of the spool. The internal leakage results in unwanted properties such as crawling of a loaded actuator in open loop systems and position error of a P-controlled loaded actuator. On the other hand system damping increases. This paper presents a robust model for internal leakage that can be identified according to known pressure gain. The importance of the valve's pressure gain on steady state and dynamic behaviour is studied by a well verified simulation model.
FREQUENCY DOMAIN MODELLING AND IDENTIFICATION OF 2D DIGITAL SERVO VALVE
J. Ruan and P. R. Ukrainetz and R. Burton,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 49-58,
Oktober 2000
view abstract
The 2D digital servo valve studied here is a two-stage valve designed by using both rotary (angular) and linear motions
of a spool. The rotary motion is driven by a stepper motor operating under continual angular displacement control,
while the linear motion of the spool is actuated by hydraulic servo control with feedback of the spool’s displacement,
which is achieved by a unique “servo screw”.
The modelling of the 2D valve is based on linear theory and is further verified by the special experiments. Because of
the extremely large hydraulic natural frequency, the control of the 2D valve is identified as being that of a
first-order-system. The relation between the time constant and the structural parameters is established, accounting for the
non-linearity of the pilot hydraulic bridge. For the continual control of the stepper motor, a mathematical model considering
the rotary motion, the rotating magnetic field and the angular control signal is established. In order to prevent the
stepper motor from losing steps, the rate of the control signal is limited to a certain range. As a result, this may cause a
non-linearity and, consequently, the deformation of the waveform when the input sinusoid wave is of large amplitude and
high frequency. By utilizing the method of the description function, the effect of limiting the rate of the control signal is approximated as a first-order-system and the relation between the time constant and the amplitude and frequency is
presented. The dynamic characteristics of the stepper motor are to a large extent dependent upon the way the power is
supplied. For a constant current supply, the stepper motor can be classified as a second-order-system. The factors affecting
the natural frequency and damping ratio are clarified. Finally, the frequency response of the 2D digital valve is
experimentally measured and compared with theoretical results. Both theoretical and experimental results show that the
2D digital valve has a fairly high frequency response, especially when the valve operates near the central position. For a 25% full scale input signal, the 2D digital servo valve has at least 300 Hz under the gain of –3 dB.
Frequency Tuning of Chain Structure Oscillators to Place the Natural Frequencies at Omega1 and N-1 Integer Multiples Omega2 ... OmegaN
J. Mikota,
In ZAMM Sonderheft GAMM,
2000, Oktober 2000
view abstract
Numerous activities in Engineering, e.g. the design of solid body compensators, involve the tuning of dynamic systems to place the natural frequencies omega_1 ... omega_N at a certain base harmonic Omega_1 and N-1 integer multiples of it Omega_2 ... Omega_N. In this paper a novel concept for the frequency tuning of multi-degree of freedom mass-spring oscillators will be presented which allows an exact placement of the natural frequencies in case of an un-damped system. Frequency tuning will be achieved by the selection of masses m_1 ... m_N and spring stiffnesses c_1 ... c_N of the system following an amazingly simple procedure.
FRICTION COMPENSATION FOR SECONDARY CONTROL LOAD SIMULATOR BASED ON FUZZY CONTROL
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
W. Xiaodong and J. Zongxia,
2002, Juli 2002
view abstract
In this paper a fuzzy controller for secondary control load simulator is presented. It can compensate the frictions
successfully and improve the dynamic performance of the system without the accurate model of the friction and the
system itself. For the theoretical investigations a mathematical model of the secondary unit is used to investigate the system’s behaviors with or without the friction models being considered. Friction model including static friction, Coulomb friction, viscous friction and Stribeck effects are also discussed in this paper. This model is a simplified description of the whole friction phenomenon, and it is so beneficial to investigate the influence of friction in simulation environment.
Furthermore, the advantages of the secondary control technology applied on the hydraulic load simulator,
compared with the traditional hydraulic servo control ones, are introduced, including the energy saving and recovery,
no position disturbance, etc. The simulation proves the effect of the fuzzy controller on friction compensation.
Friction Forces Within the Cylinder Bores of Swash-Plate Type Axial-Piston Pumps and Motors
Noah D. Manring,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 531-537,
September 1999
view abstract
In this research, the friction within the cylinder bore of a swash-plate type axial-piston machine is examined. Unlike previous research, this work develops a mathematical model for the friction based upon lubricating conditions which are described by the well-known Stribeck curve. Furthermore, a test device is built for measuring the frictional characteristics during low pressure and low speed operation and these results are compared with the mathematical model. For high pressure and high speed considerations, a numerical investigation based upon the model is conducted and it is shown that the friction associated with a pumping piston is greater than the friction associated with a motoring piston. It is also shown that increased piston speeds usually reduce the friction within the cylinder bore; however, a “cross-over” condition may exist where the increased speed will actually increase the friction as a result of increased fluid shear. Furthermore, it is shown that speed changes have a more significant impact on motoring pistons as opposed to pumping pistons due to a difference in the location of hydrodynamic lubrication within the cylinder bore. It is noted that this difference exits due to the bore geometry and the direction of piston travel.
Friction of Pneumatic Actuator Seals and its Finite Element Analysis
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
M. Achenbach and R. Boschet,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 617-629,
März 2010
view abstract
It is the main aim of the present paper to contribute to the development of adequate numerical models for leakage and friction, which may provide a helpful tool in the designing process of fluid power components. This aim involves the modelling of the tribological processes in the seal contact as well as the proper modelling of the pneumatic cylinder as a whole. Attention is confined to the seal in various loading conditions. Seal friction may possess uncertain properties due to the interference of various factors. A deeper understanding of the friction force characteristics is required for determining the motion of a pneumatic piston. An application in the field of electro-pneumatic driven power tools is presented as an example in which a reciprocating air spring operated piston strikes against a tool. This paper focuses on a new friction law which seems to be more suitable than traditional ones.
From Component Supplier to Solution Provider
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
C. A. Winter and J. Bredau,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 203-220,
März 2010
view abstract
The paper shows the development of pneumatic suppliers from providers of mere components to comprehensive solutions. First, current trends influencing pneumatics are elaborated: energy efficiency, machinery safety, diagnostics and information interoperability. Then it is illustrated how these trends can be covered by providing solutions like customizing of products, preassembled systems, complex mechatronics systems, services and training. The future development and latest research projects dealing with topics around solution providing are summarized.
Fully Integrated Electric−Hydrostatic Drive Based on a Gear Pump And a Switched Reluctance Motor
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
W. Wustmann and S. Helduser and U. Schuffenhauer and H. Kuss and N. Michalke,
2007,
volume 2,
pp. 327-339,
Mai 2007
view abstract
In accordance with the current state of the art, drive and pump are interconnected as individual components for the operation of a hydrostatic drive unit.
This article presents a drive concept in which the components of the hydraulic pump and the electric drive are functionally integrated. Using an external gear pump and a switched
reluctance motor, a compact pressure supply has been developed. The integration level of the electric motor and the hydraulic pump is higher than ever as essential functional components of the motor (rotor) are at the same time functional parts of the pump (gear wheels).
Fundamental Research on Hydraulic Oil Pumping Unit with Power Recovery
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Zheqing and R. Jian and W. Genmao ,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 266-270,
April 2005
view abstract
The research object of the paper is the crude oil well pumping unit, an important kind of equipment in oil exploiting field. A hydraulic pumping unit with power recovery is proposed. It is based on secondary principle: a new method of variable volume transmission and control in hydraulic techniques. With the application of secondary controlled mechanical-hydraulic system and hydraulic cylinder loading means, authors designed and set up an experimental device for imitating real oil pumping unit and its load. The method of parameter design of speed limiting protective device of new oil pumping unit is also considered. Steady speed performance of the prototype system is numerically simulated. The result shows its good linearity, accuracy and controllability, and it is identical with experimental result. Dynamic speed performance of oil pumping unit is investigated by numerical simulation and experiment in time domain. The result shows that dynamic speed response can meet the needs of real working condition. The probability of improving the efficiency of the sucker rod pump under the surface is indicated by employing new oil pumping unit.
Fuzzy Sky-Ground Hook Control of a Tracked Vehicle Featuring Semi-Active Electrorheological Suspension Units
Seung-Bok Choi and Dong-Won Park and Moon-Suk Suh,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 150-157,
März 2002
view abstract
This paper presents vibration control of a tracked vehicle installed with electro-rheological suspension units (ERSU). As a first step, a double-rod type ERSU is designed on the basis of the Bingham model of commercially available ER fluid, and its spring and damping characteristics are evaluated with respect to the intensity of electric fields. Subsequently, a 16 degree-of-freedom model for a tracked vehicle featuring the ERSU is established followed by the formulation of a new sky-ground hook controller. This controller takes account for both ride quality and steering stability by adopting a weighting parameter between two performance requirements. The parameter is appropriately determined by employing a fuzzy algorithm associated with two fuzzy variables: the vertical speed of the body and the rotational angular speed of the wheel. Control performances to isolate the vibration from bump and random road excitations are evaluated through computer simulations.
FUZZY VARIABLE STRUCTURE CONTROL BASED ON EVOLUTIONARY ALGORITHMS FOR HYDRAULIC SERVO SYSTEM
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
Y. Yong and L. An and K.-E. Rydberg and H. Zhixiong,
2006,
volume 2,
pp. 465-474,
Juni 2006
view abstract
The requirements of robust and accurate control become more and more practical during the modern
application of hydraulic servo systems (HSS). To balance the design conflict of hydraulic servo variable
structure control system between chattering reduction and good robustness, a fuzzy variable structure control
(FVSC) has been proposed based on evolutionary algorithms (EAs). A compound controller of fuzzy logic and
VSC has been designed. An evolutionary algorithm is used to optimize the regulating of the boundary layer
width (BLW) tuning rate. Simulation experiment results applied to the positioning control of HSS verified the
effectiveness of the proposed compound control. Satisfied comprehensive performance of HSS has been
obtained.
Fuzzy Variable Structure Position Control of a Pneumatic Muscle Actuator System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Gang and L. Baoren and F. Xiaoyun and D. Jingmin,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 357-362,
April 2005
view abstract
The purpose of this paper is to apply the fuzzy variable structure control (FVSC) method to control the position of pneumatic muscle actuator (PMA). PMA undergoes disturbances that don't satisfy the matching conditions. General variable structure control (VSC) approach leads to a disturbance-contaminated sliding surface and loses the disturbance rejection attribute. In this paper, a two-folded sliding modes approach is employed to resolve this problem. Integration of the two layers of sliding surface yields a single switching and discontinuous surface, on which the unmatched disturbances can be rejected. However, the switching surface gives rise to the undesirable "chattering" of the control input. Fuzzy theory is used to overcome the problem. The controller is designed by using Lyapunov stability theory. The effectiveness of the proposed control approach is demonstrated by experiment. The results are shown to be accurate, and robust to changes in payload and supply pressure.
GAP FLOW INVESTIGATION OF THE PISTON CYLINDER ASSEMBLY IN AXIAL PISTON PUMPS CONSIDERING EHD EFFECTS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
C. Huang,
2002, Juli 2002
view abstract
This poster presents the current status of a research project dealing with the investigation of the gap flow simulation
in the sealing and bearing gaps of displacement machines considering influence of elastohydrodynamic effects. For the
purpose of investigation, the simulation tool Caspar( Calculation of swash plate type axial piston pump and motor) is
modified and extended, to integrate the piston and bushing elastic deformation into the non-isothermal laminar gap flow
simulation, by means of so-called influence coefficient matrix using three dimensional finite element methods. The
resulting non-linear equations system, which consists of the coupled Reynolds equation, energy equation, the equation
of elasticity and the equilibrium equation of forces, is solved numerically in this program. In this paper, the influence of
the elastohydrodynamic effect on the gap flow, i.e. influence on gap height and pressure distribution, and on the
volumetric and friction losses, are discussed. The simulation results show that the material properties play a significant
role within the optimisation of the loss behaviour of the machines.
For experiment verification, a model pump for the measurement of pressure and temperature distribution in the gap
between piston and cylinder block is presented here.
Generating Vibration with Artificial Muscles
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
P. Keski−Honkola and M. Pietola,
2007,
volume 2,
pp. 261-273,
Mai 2007
view abstract
This paper presents a study on the applicability of pneumatically actuated McKibben type fluidic muscles for producing mechanical vibrations in heavy machinery. Although
McKibben type artificial fluidic muscles have been commercially available for couple of years, they are for the time being not very commonly known and used only in very restricted and special applications.
Fluidic muscles can produce even ten times the force of pneumatic cylinder with the same pressure difference and diameter. They are also practically slip-stick free which
enables them to generate smooth movements. Another feature of the muscle is that there is interdependence with force and degree of contraction. Force is reduced while the
muscle contracts. This feature enables the muscles to automatically center the position of the load when mounted in reverse-coupled manner and pressurized at the same time.
The artificial muscle actuated vibrator presented in this paper was constructed to replace a pneumatic motor-camshaft vibrator used to produce the vibration movement in a test
installation. The muscle vibrator was designed so that the frequency, waveform and amplitude of the vibration could be adjusted. The problems related to the camshaft
vibrator, like fluctuation of vibration frequency, difficulty in positioning the vibrated load and realizing an automated system were solved with the new vibrator.
Generic Tyre Model for Driving Dynamic Simulations of Off-Road Vehicles
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
A. Schumacher and H.-H. Harms,
2010,
volume 2,
pp. 603-614,
Juni 2010
view abstract
Within this work, a new tyre model is presented. Inputs of this model are the tyre dimensions as well as the operation
conditions like inflation pressure and deflection. The model requires a parameter set, which should be always available
without the need of special tests.
The verification of this empirical model was done in two separate ways. An alignment with verified tyre models and
vehicle tests. Both verifications have shown that the tyre model is very accurate. Thus, a model for offroad tyres was
developed which is on the one hand easy to use and parameterise and on the other hand delivers realistic tyre reactions
of high accuracy.
Geometric Design for a Gerotor Pump With High Area Efficiency
C.-F. Hsieh and Y.-W. Hwang,
In Journal of Mechanical Design,
2007,
volume 129,
pp. 1269-1277,
Dezember 2007
view abstract
This paper proposes a gerotor profile design based on the theory of gearing. Presented first is the curve of the outer rotor, whose conjugate profile is the inner rotor. Next, the analysis assesses the feasibility of three different design curves: an epitrochoid curve, a hypotrochoidal curve, and a curve made by continuously connecting the epicycloid and hypocycloid. The undercutting equation derived from the mathematical model - which is presented in parametric form - facilitates identification of the design parameter limits, while the sealing property and nonundercutting on the profile are estimated using curvature analyses. Finally, the offset concept is applied to the gerotor design. First, two conjugate curves are obtained, whose offset curves are the found. Pump performance - including area efficiency and sealing - is also compared for these designs, which include both offset and nonoffset rotor profiles.
Geometry Assessment of Variable Displacement Vane Pumps
Massimo Rundo and Nicola Nervegna,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 446-455 ,
Juli 2007
view abstract
The paper brings to evidence the effect that geometry of the stator ring of variable displacement radial pumps bears on performance characteristics of these units. The type of motion of the stator ring (linear or rotational), the location of the center of rotation, the porting plate integral with the casing or with the stator ring all have remarkable effects on the pump steady state and dynamic performance. At steady state, an influence exists on the attainable minimum displacement and on the deviation of discharge pressure from the desired setting when displacement is being controlled. In turn, dynamic performance is affected by changes in port plate timing as stator position and displacement undergo transitions. Specific attention is then committed to variable displacement vane pumps for internal combustion engines lubrication where an additional and foremost effect is investigated concerning the issues entailed by internal forces distribution on the stator ring that originate from incomplete chambers filling at high rotational pump speed.
Geometry based design of high dynamic servo-pneumatic valves
Proceedings of the 4th FPNI-PhD Symposium, Sarasota/Florida, 13 – 17 June 2006
Fiedler, M.; Helduser, S.; Rüdiger, F.,
2006,
volume 2,
pp. 533-541,
Juni 2006
view abstract
At present, time to market and total development costs are important criteria for a company to be competitive. It is therefore desirable to design mechatronic systems without the help of measurement results but only by applying geometrical and material data to reduce iteration steps in the very first phase of the development process. This method makes use of the functionality of today’s powerful simulation tools. The intelligent use of all the different advantages of these simulation programmes permits to develop new products most efficiently. This paper deals with the virtual design of a servo-pneumatic valve used in a multitude of applications. The main focus is the design of the one-dimensional simulation model with lumped parameters of the subsystems: valve pneumatic and proportional solenoid. Furthermore, simulation tools are needed allowing the use of distributed parameters to consider special physical effects like eddy currents or flow forces.
GEOMETRY BASED DESIGN OF HIGH DYNAMIC SERVO-PNEUMATIC VALVES
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
M. Fiedler and S. Helduser and F. Rüdiger,
2006,
volume 2,
pp. 533-541,
Juni 2006
view abstract
At present, time to market and total development costs are important criteria for a company to be competitive. It is
therefore desirable to design mechatronic systems without the help of measurement results but only by applying
geometrical and material data to reduce iteration steps in the very first phase of the development process. This method
makes use of the functionality of today’s powerful simulation tools. The intelligent use of all the different advantages of
these simulation programmes permits to develop new products most efficiently. This paper deals with the virtual design
of a servo-pneumatic valve used in a multitude of applications. The main focus is the design of the one-dimensional
simulation model with lumped parameters of the subsystems: valve pneumatic and proportional solenoid. Furthermore,
simulation tools are needed allowing the use of distributed parameters to consider special physical effects like eddy
currents or flow forces.
GEROTOR PUMP WITH HYDRAULIC COMPENSATION OF AXIAL CLEARANCE
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
S. Bednarczyk and J. Stryczek,
2000,
pp. 407-416,
September 2000
view abstract
The paper presents the design of gerotor pump with hydraulic compensation of axial clearance. The principles
of projecting of compensation of axial clearance were described. The characteristics of volumetric and the overall
efficiency was shown. The influence of the value of axial force on these characteristics was analyzed.
Haptic-Eneabled Control of Hydraulic Manipulators Applied to Power Line Maintenance: Concept and Implementation
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
K. Zarei-Nia and N. Sepehri and T. Olson and W. Mueller,
2010,
volume 2,
pp. 633-642,
Juni 2010
view abstract
In this paper, we present development of a scheme enabling a commercially available hydraulic robot to work with a
haptic device performing live-line maintenance tasks. Presently live line maintenance is done manually by operators
working in locations high above the ground and near high voltage power lines. Ground-level teleoperation of a
hydraulic manipulator using a haptic device can potentially increase safety and productivity. The proposed haptorobotic
system is built upon the concept of virtual fixtures. Impedance-type forbidden region virtual fixture is used to
help the robot to perform tasks. The control system configures virtual fixtures in the workspace based on the required
task. The effectiveness of the system is shown by emulating several live power line maintenance tasks in the laboratory.
It is shown that many tasks can be done even by an unskilled operator using the proposed haptically-enabled
teleoperation system, which uses intelligence of the human operator along with the accuracy of the manipulator.
HAPTIC ENHANCEMENT OF HYDRAULIC EQUIUPMENT
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
M. E. Kontz and W. J. Book,
2006,
volume 2,
pp. 497-506,
Juni 2006
view abstract
As electro-hydraulic valves and microprocessors become a common place on commercial mobile hydraulic machinery,
this opens the door to a host of enhancing features that can be implemented via computer control. One potentially
enhancing feature is to replace the traditional joysticks/levers with a single multi-degree of freedom haptic interface.
This allows information to flow back to the operator in the form of force signals. These force signals can be used to
relay information about digging force, joint constraints, flow limits, desired digging depth or other programmable
features. This type of programmable interface also allows the motion of the operator’s hand to be mapped directly to
the position and orientation of an end effector such as an excavator’s bucket. This provides a more intuitive interface
for novice and occasional operators. Near expert level of dexterity has been demonstrated in a relatively short period
of time by novice operators. This project aims to help bridge the gap between the hydraulic and robotic issue required
to make haptic coordinated control of hydraulic machinery a cost-effective reality. Results will be presented from two
different projects: HAL and HEnRE. HAL (Hydraulically Actuated Lifter) is a laboratory version of a forklift truck and
HEnRE (Haptically ENhanced Robotics Excavator) is a small, tractor-mounted backhoe that has been instrumented
and equipped with proportional electro-hydraulic valves.
Hardware-in-the -Loop Simulation Experiments with a Hydraulic Manipulator Model
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
J. A. Ferreira and A. F. Quintã and C. M. Cabral,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 413-422,
November 2003
view abstract
Hardware-in-the-loop simulation (HILS) is a technique that allows a simulation model to
interact with real-world components, that is, one part of a system can be a simulation model,
when other parts of the system are the actual hardware.
This paper presents the development of a hydraulic SCARA (Selective Complience Assembly
Robot Arm) manipulator model with the purpose of using it in hardware-in-the-loop
simulation experiments. Most of the mathematical models are semi-empirical in order to
reduce the required simulation time and to perform real time simulations in small cost
platforms. Two small cost acquisition boards from National instruments, installed in a
PentiumIII PC, were used to connect the real time simulation to the real world. The real time
simulations run in the xPC platform from Mathworks. Position control experiments,
following typical robot trajectories, were made with PD controllers implemented with
operational amplifiers. The results obtained in the HILS experiments were very satisfactory,
considering that semi-empirical models were used.
High Accuracy Positioning and Synchronizing Two Hydraulic Cylinders in a Hydraulic Press Brake
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
M. Yahyaei and E. Sanei and N. Pouladi,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 305-317,
März 2010
view abstract
There are various applications in industry that need two cylinders be synchronized. Moreover, some methods are available for synchronization while some are cheap and imprecise and some are precise and expensive. In this paper we propose our recent work which is a high accuracy positioning and synchronizing system in a CNC hydraulic press brake. In this work we control each cylinder independently by a proportional directional control valve with pilot and main stages electrical position transducers. These two valves are driven by two power amplifiers with CNC Adaptation Module. In order to reduce the amount of expense we used this amplifier hence, instead of using an expensive servo valve, we can implement high accuracy positioning system (0.08 mm precision) with an inexpensive overlapped proportional valve. Nonlinearities and inconsistencies in the dead band region, which are undesirable for closed loop positioning system, are compensated by the electronic linearization. In this work we defined the velocity profile of each cylinder in the PLC and by using PI Controller in PLC we reached to 0.08 mm precision for synchronization of two hydraulic cylinders in this press brake.
High Efficiency at 200−2000 rpm and 10−30 MPa: Vane−In−Groove Pumps with Adaptive Rotor
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
A. Stroganov and L. Sheshin and Y. Volkov and S. Ryadnov and A. Nikiforov,
2007,
volume 1,
pp. 243-249,
Mai 2007
view abstract
Paper presents a development aimed at substantial reduction of friction losses and leakages level in vane pumps with a working chamber made in annular groove in a rotor face. Since sealing surfaces of a rotor and a housing are flat and vanes are fixed in the annular groove rigidly working fluid leakages are very small. Thus this type of vane pumps (called Vane-In-Groove) achieves high volumetric efficiency at wide range of
rotation speed and operational pressure.
The new rotor design (called adaptive) comprises two parts: working and supporting, and provides Vane-In-Groove pump with good hydrostatic axial balancing of both parts of adaptive rotor. This allows to reduce friction forces between rotor parts and cover plates of the housing. Thus with adaptive rotor design high mechanical efficiency can be reached as well.
Paper describes one type of Vane-In-Groove pump architecture. It has an adaptive rotor located between housing cover plates and is preferable for variable displacement machines.
The tests equipment, schematic diagram and procedure for volumetric and overall efficiency measurement are presented as well as the tests results for 28 cm3 pump. The test results illustrate high volumetric and overall efficiency at 200 – 2000 RPM and 5 – 30 MPa.
Higher-order sliding modes for an electropneumatic system: differentiation and output-feedback control
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
L. Sidhom and M. Smaoui and M. D. Loreto and X. Brun and E. Bideaux and D. Thomasset,
2008,
pp. 383-392,
September 2008
view abstract
This paper develops and uses a robust differentiator via sliding modes applied to velocity and acceleration measurements. From the only measure of the position, we are being able to accurately estimate the velocity and the acceleration of a servo drive system. Initially developed by Levant, this differentiator is based on high-order sliding modes. The goal of this work is to show the importance of the choice of the differentiator design in the control of an electropneumatic system. A comparative study is made between the 2nd-order robust differentiator and a classic digital differentiation algorithm, in order to show the influence of the structure differentiation algorithm on the control of the electropneumatic system.
High-frequency axial vibration in a combined pump unit with gear stage
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
M. Gasparov and A. Kruchkov and L. Rodionov and E. Shakhmatov,
2007,
pp. 117-127,
September 2007
view abstract
In the paper reasons of high axial vibrations of the pump unit including gear and screwcentrifugal stages are investigated. It is shown that the gear stage is a main source of axial vibrations. The essential increase in the axial forces is due to the asymmetrical (in the axial direction) hydraulic unloading of the closed volumes. The axial displacements of the mobile axial bearing under pressure oscillations cause high-frequency axial vibration. From mobile and motionless axial bearings it is transferred to the manifold and further the screw-centrifugal rotor vibration is excited. Calculation of the axial forces acting in the gear stage is presented in the paper. The model of high-frequency vibrations of the pump is developed. The results of simulation have been verified through comparison with experimental data.
Highly Durable and Abrasion Resistant Superhydrophobic Organoclay Nanocomposite Films
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
A. Steele and I. Bayer and P. Martorana and E. Loth,
2010,
volume 1,
pp. 399-406,
Juni 2010
view abstract
Adhesives cured by a redox initiated free radical mechanism have been used extensively in the aerospace and
automotive industry for locking and sealing. Acrylic anaerobic adhesives belong to this class of adhesives which cure in the absence of oxygen. Similarly, acrylic medical adhesives such as bone cements also cure via anaerobic mechanisms.
The two main components of both types of adhesives are a liquid methacrylate monomer and a small amount of
hydroperoxide. In the current investigation, we report the fabrication of tough nanostructured self-cleaning
superhydrophobic polymer-organoclay films from such anaerobic acrylic adhesives. Note that no post-surface
treatment was required to render the films superhydrophobic. Such films may have applications both for lubrication
improvement in fluid pumps as well as for pressure loss reduction in fluid transmission lines. Here, montmorillonite
clay filled anaerobic adhesives were modified by blending with a water dispersed fluoro-methacrylic latex in solution to
form abrasion resistant interpenetrating polymer network films upon spray casting. Very high contact angles with low
hysteresis were also measured for acidic (pH 2) and basic (pH 11) aqueous buffer solutions indicating resistance to
acidic and basic media. By spraying two successive coatings, thicker films on the order of 120 μm were also fabricated.
These films could withstand sandpaper abrasion while maintaining their self-cleaning superhydrophobicity, even
though several microns of material were removed. This property was due to the inherent self-similarity of the micro and nanostructure throughout the thickness of the film, as confirmed by characterizing the surface morphology using an
environmental scanning electron microscope. It was also noted that the anaerobic acrylic adhesive based compositions
in particular displayed very strong adhesion to metal surfaces.
High Performance Digital Hydraulic Servo System for Linear Cyclic Motion
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
V. Ahola and M. Linjama and M. Vilenius,
2007,
volume 2,
pp. 275-287,
Mai 2007
view abstract
Hydraulic actuation has been popular in linear cyclic motion because of high power-toweight ratio. Good control performance and good repeatability are important in order to
achieve high quality. Therefore, servo valves are usually used as control valves.
Problems with servo valve are high cost as well as sensitivity for contamination and vibrations. Required high flow rates and high bandwidth are also difficult to satisfy.
These problems could be reduced if fast on/off valves were used instead of servo valve.
In this paper, the two-stage servo cartridge valve is replaced with parallel-connected on/off valves. 5+3 valves are used to control inflow and outflow of the cylinder actuator. Controller is developed for this Digital Hydraulic solution and control
performance is compared with traditional system. Results show that digital hydraulic valve system gives better control performance and is therefore a potential solution.
HIGH PRECISION CONTROL SYSTEM FOR HYDRAULIC CYLINDER
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
R. Amirante and A. Lippolis and V. Marzullo,
2002, Juli 2002
view abstract
The aim of this study is to develop a precision driving system actuated by a hydraulic cylinder driven by a proportional four
way valve. In order to optimise the design parameters and to study the interaction between the proportional valve and the
cylinder, numerical simulation analysis as well as experimental test are performed. A comparison between numerical results
and experimental data is presented. The experimental data have been taken on a test rig located at the Politecnico di Bari.
First the frequency response of "proportional valve-cylinder" system is experimentally obtained. The attention of this analysis
is also focused on the ratio between the cylinder natural frequency and valve one.
The achieved results match reasonably well the literature data as well as the numerical results by means of a simulation code.
Typically the commercial valves are characterized by a critical dampening-factor so that they do not show any resonance
frequency, while the cylinders show relevant resonance phenomena. When combining the two components, it is crucial to
know the ratio of their natural frequencies. In particular, if the valve is characterized by a lower natural frequency, its behaviour
prevails so that no resonance peak can be observed. On the contrary, some resonance phenomena can be observed in all the
other cases. It is very important that all these phenomena are taken into account to realise a precise and accurate control of a
hydraulic axle.
Subsequently the attention is focused on the control technique. Three different control methods are presented:
1. a PID technique;
2. an expert control technique based on the valve-cylinder system characteristics;
3. an adaptive “One-Step-Ahead” control technique.
The final goal is to control by means of a hydraulic control system a horizontal machine center.
High Precision Hydrostatic Actuation Systems for Micro- and Nanomanipulation of Heavy Loads
Saeid Habibi and Richard Burton and Eric Sampson,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 778-787,
Dezember 2006
view abstract
In this paper reports on an important finding, that is, hydrostatic actuation systems are able to manipulate heavy loads with submicron precision and a large stroke. In this relation, the design of a high-precision hydrostatic actuation system referred to as the ElectroHydraulic Actuator (EHA) is presented. A laboratory prototype of this system has achieved an unprecedented level of performance by being able to move a large load of 20 Kg with a precision of 100 nm and a stroke of 12 cm. This level of performance places the hydrostatic actuation concept in competition with piezoelectric platforms in terms of positional accuracy. Experimental results from this prototype are reported and analyzed.
High-pressure properties of hydraulic fluids - measuring and differences
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
J.-P. Karjalainen and R. Karjalainen and K. Huhtala and M. Vilenius,
2006,
pp. 67-79,
September 2006
view abstract
Hydraulic fluid and its properties have a particularly significant role in accurate highpressure systems design and performance, such as common rail diesel injection systems. However, for a designer there is quite inadequate and inaccurate information available on the properties of different types of hydraulic fluids – especially at high pressures.
In this paper the measuring principles for determining the most important fluid parameters – bulk modulus, density, sound velocity and viscosity – are introduced. The measurements were carried out with different types of commercial hydraulic fluids at pressures up to 1500 bar at different temperatures. The dynamic parameters (sound velocity, bulk modulus, density) were measured using a system based on defining the pressure wave propagation time in a rigid straight pipe. The viscosity was measured using a modified falling ball viscometer.
High-Speed Switching Valves Actuated by Parametrically Excited Structures
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 1999
M. Garstenauer and R. Scheidl,
1999,
pp. 137-150,
September 1999
view abstract
In this article we describe a new concept for high speed, low power hydraulic switching valves that achieve transition times below 1 ms. Key element is a parametrically excited elastic structure that serves both as energy storage and displacement magnifier. Experimental results for a hydraulically controlled prototype are presented, and design studies for a future prototype with piezoelectic actuators are discussed. Applications for such valves are the implementation of energy efficient switching techniques in hydraulic drives and the replacement of servo valves by lower cost, very high speed switching valves for servo-controlled drives.
Homotopy perturbation analysis of slider bearing with Powell-Eyring fluid
S. Islam and Abdullah Shah and C. Y. Zhou and Ishtiaq Ali,
In Journal of Applied Mathematics and Physics,
2009,
volume 60,
pp. 1178-1193,
view abstract
An analytical solution of an infinite lubricated inclined slider bearing with non-Newtonian Powell-Eyring fluid as lubricant is presented. The homotopy perturbation method (HPM) is used and solutions for velocity components and pressure distribution in the slider bearing are derived with the method. The pressure distributions in the bearing are illustrated graphically for a range of non-Newtonian fluid material and bearing geometric parameters, and the effects of these parameters on the load carrying capacity of the bearing are discussed.
HOW CASE-BASEDMETHODS CAN AUTOMATE FLUIDIC CIRCUIT DESIGN
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
B. Stein,
2000,
pp. 137-148,
September 2000
view abstract
Designing a system means to transform a set of demands, D, towards an explicit system description, S. In the
field of fluidic circuit design, components like pumps, valves, and cylinders are used to construct S. From a
configurational standpoint a designer selects, parameterizes, and connects components such that D is fulfilled by
the emerging circuit.
Actually, fluidic circuit design is not tackled at the component level. Instead, a designer develops a mental model
of the desired system, which is placed at the level of function, F. Hence, a more adequate characterization of the
design process is D -> F -> S.
Using the concept of fluidic axes, the step F -> S can be automated by means of case-based reasoning. Motivated
by these observations we have developed a case-based design approach for hydraulic systems.
How to Handle Auxiliary Functions in Energy Efficient, Single Pump, Flow Sharing Mobile Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Eriksson, Björn and J.-O. Palmberg,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 65-78,
März 2010
view abstract
Interest has increasingly shifted from load-sensing (pressure controlled) systems to flow controlled systems. In this paper an interesting configuration that uses pre-compensated valves with flow sharing properties is studied. The fundamental difference between a traditional load sensing (LS) system and a flow controlled system is that the pump is controlled based on the operator’s total flow demand rather than maintaining a certain margin pressure over the maximum load pressure. One of the main advantages with flow controlled systems is the absence of the feedback of the highest load pressure to the pump. Flow controlled systems also present some challenges, one being how to handle auxiliary functions with unknown flow demands. Auxiliary functions are typically support legs, external power takeouts etc. This paper analyses one kind of flow controlled system and shows one way of dealing with auxiliary functions.
H¥ Pi Plus Feedforward Controller Design for an Electrohydraulic Actuator (EHA) System
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
Y. Lin and H. Zhang and Y. Shi and R. Burton,
2010,
volume 1,
pp. 143-152,
Juni 2010
view abstract
This paper studies the design of a PI plus feedforward controller for a high precision electro-hydraulic actuator (EHA) system. The high precision positioning EHA system is capable of achieving a very high accuracy positioning
performance. Many more sophisticated control schemes have been developed to address these problems. However, PID
control is still the most popular control strategy using in industrial applications. Therefore, the main objective of this
work is to design a PI controller for the EHA system, improving its performance while maintaining and enjoying the
simple structure of the PI controller. An extra feedforward term is introduced into the PI controller to compensate for
the error especially existing during the tracking period. The PI plus feedforward control design is augmented into a
static output feedback (SOF) control design problem and the SOF controller is designed by solving an H¥ optimization
problem with bilinear matrix inequalities (BMIs).
Hybrid Analytical/Neural Network Model of Variable Displacement Pump Dynamics
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
J. M. McNamara and N. D. Vaughan and K. A. Edge,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 71-76,
November 1997
view abstract
The response of a variable displacement pump to a control signal can be an important factor in the overall system response. It is therefore necessary in simulating such systems to have an accurate model of the dynamic behaviour of the pump and its interaction with the system. This paper presents a comprehensive model of a typical variable displacement swash-plate piston pump and its servo controller.
Because of the complex and non-linear form of the pumping dynamics previous researchers have used over-simplified models, particularly in respect of swash-plate forces during the pumping cycle. This paper describes a hybrid approach which combines physical models and a neural network to simulate swash-plate dynamics. Training data for the neural network is obtained through a detailed simulation of pumping dynamics. This allows the creation of a black-box model of swash-plate moments as a function of delivery pressure and swash-plate position and velocity.
Training data and the hybrid model of the pump system have been verified experimentally. The final pump system model takes into account the interactions between pump, its controller and the delivery line.
Hybrid Particle-Element Bond Graphs for Impact Dynamics Simulation
E. P. Fahrenthold and J. C. Koo,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 306-313,
Juni 2000
view abstract
Particle methods offer an efficient modeling approach to number of impact dynamics problems not well suited to conventional Eulerian finite difference or Lagrangian finite element methods. Unfortunately, the most popular of these particle methods (smooth particle hydrodynamics) exhibits important deficiencies, in part related to its treatment of boundaries and interparticle tension, and suffers from a rather ad hoc model formulation approach. A hybrid particle-element kinematic scheme and an energy-based, bond graph modeling approach have been combined to produce a new impact dynamics simulation method, free of many problems which have hindered the effective application of various particle and continuum methods.
HYBRID PRESSURE CONTROL CONCEPT FOR A SPEED VARIABLE AC MOTOR PUMP IN AEROSPACE APPLICATION
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
J. Engelhardt and C. Greissner,
2002, Juli 2002
view abstract
This paper describes a new pressure control strategy for AC motor driven pumps in aircraft application. Both, swash
plate position and pump speed are used for controlling system pressure in a hybrid approach. The requirements for the
pressure control loop and the design methods for the hybrid control circuits with a load observer are introduced. The
new control concept has been implemented into an experimental set-up. The validation and evaluation of simulation
results on the test rig are discussed in detail. Finally, the new hybrid approach is compared to the conventional approach
concerning efficiency, noise level and wear for typical aircraft flight missions.
Hydraulic Accumulators as Key Components in Energy Efficient Mobile Systems
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
K.-E. Rydberg,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 124-129,
April 2005
view abstract
In the development of more energy efficient machineries the hydraulic System design and the fluid properties are of great importance. For hydraulically driven machines, operating in a cyclic manner the energy consumption can be considerably reduced, by using hydraulic accumulators as energy storage devices. In the design of a system equipped with a hydraulic accumulator there are two important aspects to consider. One is how the system performs from the energy point of view.
Secondly, to get really good use of the accumulator the designer has to consider how it will affect the need of power supply.
By using the accumulator as an energy storing devise, where some of the potential energy can be reused, it is possible to design a system with improved endurance compared with a similar one without such a system. The reduced energy consumption of the hydraulic system will affect not only the performance but also the environment in a favorable way.
To get full advantage of the accumulator the designer should not only focus on the energy consumption. Since the accumulator adds a higher power supply capability, the system should also be optimized in terms of the need of power. Optimizing the system in this way will give the designer a couple of new alternatives. The additional power can be used to increase the performance of the system, without increasing the power from the existing hydraulic supply units. Another choice would of course be to use this power to reduce the size of the other components.
The aim of this paper is to show how a hydraulic accumulator can be used in mobile hydraulic systems in order to reduce energy consumption and achieve increased performances. The amount of saved energy and need of supply power is determined by simulation and optimization. The importance of laboratory tests to verify the simulation model for the system is denoted. The main result of this work is that the most important design parameters for accumulator system have been examined and quantified in a way that they can become useful for further system development.
Hydraulically Foldable Wind Energy Plant for Regions Susceptible to Storm Hazards
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
C. Stammen and G. Erdmann and D. Prust,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 467-476,
März 2010
view abstract
This paper describes the motivation for the development of the foldable wind turbine and illustrates its hydraulics in compliance with the given constraints as imposed by the new functionality. In order to design an adequate hydraulic system as well as a closed loop control adapted to the special dimensions of the installation, the hydraulic system was analyzed by means of a simulation model. By defining an optimized trajectory on which the folding mechanism moves during its operation, the loads imposed on the cylinders as well as the structure can be reduced. The coordinated movement of the hydraulic cylinders is controlled by variable displacement pumps which are governed by a PLC. The paper exemplifies the control design by means of the simulation model and presents a comparison between simulation results and test readings obtained from the full scale prototype with 45 m height.
HYDRAULIC AND TRIBOLOGICAL INVESTIGATION OF INJECTION SYSTEMS FOR FUELS FROM BIOMASS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
S. Drumm and A. Wohlers and A. Fatemi and H. Murrenhoff,
2008,
pp. 237-244,
Juli 2008
view abstract
The Excellence Cluster “Tailor-made Fuels from Biomass”, funded by the German research foundation (DFG), is an
interdisciplinary co-operation of 15 institutes with about 50 academics. Aim of the project is to find an economic way of
fuel production from biomass, and furthermore to optimise the conventional combustion process considering the
properties of this novel type of fluid. The task of the authors is to develop design rules for injection systems for these
fuels. Conveying fuel from the tank to the injection nozzles is an essential part of the research. High pressure pumping
of low viscosity media without lubricating additives is a technological challenge and requires a special attention to
material compounds and surfaces that are interacting with the fuels. The research is needed to avoid excessive wear,
minimize energy losses and reliability problems in future applications of tailor-made fuels. It provides a feedback of
fuel data to the fuel design team within the cluster.
The present paper will show the approach to find a technical solution to deal with these challenges. First the critical
aspects in the injection system for the fuels from biomass will be presented. Furthermore the investigations to
characterise the new fuels will be explained. The focus will be set on fluid properties under high pressure conditions.
The test rigs that have to be designed for measuring viscosity and bulk modulus of these fluids will be presented. The
paper will show the different measuring principles for these extreme conditions. A tribometer will be used to study the
interaction between fluids and surfaces for mixed lubrication, and first design steps are introduced in the presentation.
All these data are needed to parameterise simulation models of the injection system which will be set up parallel to the
experiments.
HYDRAULIC BRIDGE FOR PRESSURE CONTROL IN A P-Q MULTIPLE LINE SEGMENT CONTROL VALVE
R. Burton and J. Ruan and P. R. Ukrainetz,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 5-15,
November 2003
view abstract
The conventional device for flow rate and pressure multiple control is a combination of a flow rate valve and a pressure
relief valve. For the pressure control, a hydraulic bridge can also be used instead of using a pressure relief valve. In
this paper, a special hydraulic bridge was developed to undertake pressure control in a pressure compensated flow rate
valve and thus a new type of P-Q control valve is constructed. The pressure control in this P-Q control valve is a hydraulic
bridge formed by the serial connection between a metering orifice and a drain orifice. The contour of the valve
port has a significant effect on the linearity of the output pressure. Theoretical analysis shows that the linear pressure
output characteristic corresponds to a valve port contour of a hyperbolic. Due to the difficult machining of this hyperbolic
contour, a multiple line with two segment lines is used to approximate the valve port contour for linear pressure
output. The pressure bridge is constructed in a 2D P-Q control valve and an experimental investigation is carried out. It
is demonstrated that linearity of the output pressure is greatly improved by using the multiple segment line contour of
the valve port and it is demonstrated that the output pressure is not sensitive to the variation of the temperature. With
the introduction of the pressure control bridge, the P-Q valve is indeed greatly simplified.
Hydraulic Circuit Test Device of Directional Vehicle Control (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
M. Lachman and J. Cerha,
2008,
pp. 230-236,
September 2008
view abstract
directional vehicle control is assured mostly mechanical or mechanical hydraulic. Hydraulic system is use in heavy and slowly ridden manipulation, building or agricultural machines. Even if car EU safety rules requires mechanical connection between steering wheel and wheels, designed test device has to verify properties of electro hydraulic system of directional vehicle control without those bindings (Steer by Wire). So conceived machinery in his complexity can offer various, theoretical function, bringing drivers comfort in car handling. Test bench was designed by workers of the department of vehicles and motors within grant GACR (Czech Science Foundation).
Hydraulic circuit of test device of directional vehicle control (fig. 1) consists of:
• source of pressure fluid,
• control elements, designed as one unit (cube)
• two linear motors (cylinders).
Dominant elements, which properties will influence behavior hydraulic parts mechanism of directional drive vehicle wheel are control valve and fluid motor with load.
Pilot valves are proportional distributors of Parker series D1FP (fig.3). Control valve is in symmetrical form with zero overlap of control edges (E50B) and with flow 3 dm3. min-1 at pressure gradient 3,5 MPa.
Linear double action fluid motors with one - sided piston rod are Parker series HMI (piston diameter 32 mm and piston rod 22 mm) with standard type piston seal and piston rod. Active area rate α = S1/S2 = 1,896 (S1 is area on the side piston and S2 area on the side piston rod).
Connection of „ unsymmetrical" motor with symmetric pilot valve establishes process load characteristic of this drive layout, see fig. 5. From graphic representation is evident, that the piston moves forward faster than backward move.
Another fact resulting from unsymmetrical form motor is his rigidity and related natural frequency of undamped oscillations of hydraulic-mechanical system. If the slide-valve overlap will be positive, i.e., in the central position both half - space of motor will be blocked, rigidity of motor changes with his stroke, or turning wheels so, how is visible on fig. 6. If slide-valve in neutral position will have some permeability (e.g. influence of functional clearance on zero overlap) rigidity system will be lower in comparison with previous case.
Simulation of electro hydraulic system will execute in program Matlab – SimScape. Verification will be executed on the basis experiments with designed test device of directional vehicle control.
Hydraulic controlled polyester-based micro adaptive mirror with adjustable focal length
A. A. Alzaydi and J. T. W. Yeow and S. L. Lee,
In Mechatronics,
2008,
volume 18,
pp. 61-70,
März 2008
view abstract
Currently micro-electromechanical systems (MEMS) technology is creating micro-mirrors for applications such as scanning and adaptive optics. A 0.5 µm thin, reflective polyester sheet is used to create a 950 µm diameter flexible mirror that is capable of changing its concavity. A system that consists of electrical circuits and LabVIEW interfaces were used to control the mirror. This paper presents a micro-mirror that is fabricated from a 0.5 µm thin, reflective polyester sheet clamped with aluminum disks. An electromagnetic plunge actuator controls the pressure beneath the mirror to change the curvature of the mirror. The focal point of the micro-mirror ranges from approximately infinity to 3.5 mm. This range is much wider than the ranges that are typical of MEMS mirrors. The curvature of the micro-mirror can be altered at a maximum observable frequency of about 15 Hz. The micro-mirror depth movement is at increments of approximately 2 µm and the focal length increment of change is approximately 5 mm. The mirror is capable of dynamically focusing on objects at a distance of 6 cm to longer than 7 m away from the mirror.
HYDRAULIC DAMPING DEVICE IN SERVOSOLENOIDS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
M. Sorli and A. Guala and S. Pastorelli,
2002, Juli 2002
view abstract
The aim of this paper is to present a dynamic model of hydraulic damping effect in servosolenoids, in order to
obtain a useful tool to simulate and predict the behaviour of those components when implemented in complex systems,
such as proportional valves. A non-linear mathematical model is defined using a lumped-parameter approach. The
equations composing the mathematical model are then implemented in Matlab-Simulink software environment and the
non-linear hydraulic model is then connected to a complete flow proportional valve model. The validation procedure of
the complete valve model shows that experimental data are appreciably simulated. Hence the stand-alone hydraulic
damper model is tested under different velocity input time-histories.
Finally, the paper shows and discuss the influence of characteristic geometrical data of the hydraulic circuit
integrated in the servosolenoid on the dynamic damping force developed behaviour.
Hydraulic drive control concepts with two 3/3-way valves in contrast to classical 4/3 valve
Proceedings of 4th FPNI - PhD Symposium Sarasota, Florida, USA, 2006
ISBN: ISBN: 1-4243-0500-4,
P. Konarik,
FPNI Fluid Power Net Publications - Coastal Printing,
ed. ,
2006,
volume 2,
pp. 507-521,
view abstract
Present implementations, time responses and requirements for control of systems become more accurate, faster and complex. Together with acceptance of energetic demand, installation and service costs present a difficult task.
This paper presents functional exchange of a classical three-position four-way valve for two 3/3-way valves including design of control concepts, control algorithm synthesis, and verification with comparison both valve configurations and concepts.
Computation power today Action members, computers and microprocessor units are still heading forward, also in area of hydraulic valve systems. These systems work as power gains and they realize controlled throttling on throttling edge, which is called resistance control. One edge valves or two edges valves, their combinations, and 3/3-way valves used in the paper enable controlling each chamber of hydromotor separately as independent control action members. The case of two three-position of three way valves can realize the same functions as classical three position four-way valve but with additional control degree of freedom, which could be in several cases profitable .
In the paper 3/3-way valves with negative overlap are considered. These valves were selected for the possibility to produce them cheaper in the future. For example, they can be built into corpus of hydromotors in a patron form with reduced precision of production, which can be then compensated by suitable control, based on measured, estimated valve characteristics or approximated valve characteristics described through coefficients.
Independent control of each control valve allows realizing a range of control concepts focusing on specific hydraulic drive control requirements. For example one of possible hydraulic drive control concept allows bringing hydraulic circuit behaviour and its unsymmetrical pressure and flow characteristics of circuit realization with one side piston of hydromotor to behaviour of hydraulic circuit with symmetrical piston of hydromotor with respect to symmetrical pressure and flow characteristics.
Also, control concepts are able to evolve further possible realizations based on computer controlled combinations of hydraulic halfbridges.
HYDRAULIC DRIVE CONTROL CONCEPTS WITH TWO 3/3- WAY VALVES IN CONTRAST TO CLASSICAL 4/3 VALVE
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
P. Konarik,
2006,
volume 2,
pp. 507-522,
Juni 2006
view abstract
Present implementations, time responses and requirements for control of systems become more
accurate, faster and complex. Together with acceptance of energetic demand, installation and service
costs present a difficult task.
This paper presents functional exchange of a classical three-position four-way valve for two 3/3-way
valves including design of control concepts, control algorithm synthesis, and verification with comparison
both valve configurations and concepts.
Computation power today Action members, computers and microprocessor units are still heading
forward, also in area of hydraulic valve systems. These systems work as power gains and they realize
controlled throttling on throttling edge, which is called resistance control. One edge valves or two edges
valves, their combinations, and 3/3-way valves used in the paper enable controlling each chamber of
hydromotor separately as independent control action members. The case of two three-position of three
way valves can realize the same functions as classical three position four-way valve but with additional
control degree of freedom, which could be in several cases profitable .
In the paper 3/3-way valves with negative overlap are considered. These valves were selected for the
possibility to produce them cheaper in the future. For example, they can be built into corpus of
hydromotors in a patron form with reduced precision of production, which can be then compensated by
suitable control, based on measured, estimated valve characteristics or approximated valve
characteristics described through coefficients.
Independent control of each control valve allows realizing a range of control concepts focusing on
specific hydraulic drive control requirements. For example one of possible hydraulic drive control
concept allows bringing hydraulic circuit behaviour and its unsymmetrical pressure and flow
characteristics of circuit realization with one side piston of hydromotor to behaviour of hydraulic circuit
with symmetrical piston of hydromotor with respect to symmetrical pressure and flow characteristics.
Also, control concepts are able to evolve further possible realizations based on computer controlled
combinations of hydraulic halfbridges.
Hydraulic Drives Control Use Non-Robust and Robust Control Algorithms
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
P. Koňařík,
2004,
pp. 291-300,
Juni 2004
view abstract
The paper deals with the synthesis, realization, practical verification and comparison of the
conventional control algorithms and a new control algorithms. The algorithms are based on the method of
the state variables aggregation which has been developed at the Department of Control System and
Instrumentation. These are non-robust and robust control algorithms, which are suitable for the control of
more complex non-linear time variant systems of a higher order, where determination of a time accurate
model can be more complicated, extensive or unattainable. A practical comparison will be reduced to only
robust control algorithms due to computational demand of a non-robust control algorithm and its
implementation.
A controlled non-linear system is configured as a four-way flow servo-valve and a hydromotor with
one side piston, that can be controlled only by the one control action value u, enforcing the servo-valve,
while there might be many more required output state variables, for example position, velocity,
acceleration or pressure. Designed robust algorithms are able to follow previously mentioned requirements
in real time by optimal, and at the same time, with indirectly energy low cost control even without the
knowledge of accurate mathematical model of the control system.
Hydraulic Drives Control Use Non-Robust and Robust Control Algorithms
Proceedings of 3rd International PhD Symposium on Fluid Power, Barcelona-Terrassa, Spain, 2004
ISBN: ISBN 84-609-1354-6,
P. Konarik,
Technical University of Catalonia, Barcelona-Terrassa,
ed. ,
2004,
pp. 291-300,
view abstract
The paper deals with the synthesis, realization, practical verification and comparison of the conventional control algorithms and a new control algorithms. The algorithms are based on the method of the state variables aggregation which has been developed at the Department of Control System and Instrumentation. These are non-robust and robust control algorithms, which are suitable for the control of more complex non-linear time variant systems of a higher order, where determination of a time accurate model can be more complicated, extensive or unattainable. A practical comparison will be reduced to only robust control algorithms due to computational demand of a non-robust control algorithm and its implementation.
A controlled non-linear system is configured as a four-way flow servo-valve and a hydromotor with one side piston, that can be controlled only by the one control action value u, enforcing the servo-valve, while there might be many more required output state variables, for example position, velocity, acceleration or pressure. Designed robust algorithms are able to follow previously mentioned requirements in real time by optimal, and at the same time, with indirectly energy low cost control even without the knowledge of accurate mathematical model of the control system.
Hydraulic Flow Compensator for Fast Switching Devices
William de Ojeda and Francisco Ruiz,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 509-514,
September 2003
view abstract
A hydraulic circuit design composed of a pressure-regulating device in conjunction with a spring-loaded flow compensator is shown to be an effective mechanism to improve the pressure control functionality, specifically by minimizing the excursions of pressures experimented in the system and by minimizing the time required by the supply pump to restore pressure. The design stores fluid energy and restores it to a system where fast switching devices control fluid consumption. The effectiveness of the mechanism resides in controlling the back pressure on the pressure regulator and compensator to just below the system pressure. The flow compensator can reduce pressure recovery times by over 60% and minimize pressure drops by 20%. The compensator effectively allows for better pump size optimization and smaller required volumes for added power savings and better packaging.
Hydraulic Fluid Quality in Aircraft Hydraulic Systems
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
J. Aaltonen and K. T. Koskinen and M. Vilenius and K. Vaaraniemi,
2007,
volume 1,
pp. 167-179,
Mai 2007
view abstract
Ambient temperature variation aircraft hydraulic systems have to withstand can be nearly 90ºC. Besides of the ambient temperature the hydraulic systems have to withstand very high variation in system temperature. Due to small fluid volume, limited heat exchanger capacity and high system peak power these systems usually run exceptionally hot and fluid may have to withstand a temperature variation as high as nearly 180 ºC. Violent ambient conditions and extreme conditions in the system itself cause hydraulic fluid to be under very exceptional stress in comparison to typical mobile hydraulic systems. Also hydraulic system maintenance and servicing practices in aircraft differ a great deal from practices used in other mobile hydraulic systems.
Fluid contamination and deterioration are normal consequences of the system operation and ambient conditions. Performance, lifetime and reliability of hydraulic components are very sensitive to the quality of the hydraulic fluid used in the system and thus is of great importance to know the overall quality of the fluid in the system and to understand
how the quality is affected by maintenance and servicing.
This paper presents results of the fluid quality monitoring study made in two different types of aircraft using different types of hydraulic fluid (mineral oil based and synthetic
hydrocarbon). Four individual aircrafts were selected for research and fluid from each aircraft was sampled periodically. Typical parameters describing the fluid quality (TAN,
viscosity, water content etc.) were analysed from samples. Also the level of particulate contamination was determined. Results give an explanation to many typical problems encountered in aircraft hydraulic systems and also point out short comings of typical maintenance servicing procedures used in aircraft hydraulics.
Hydraulic Fluid Viscosity Selection for Improved Fuel Economy
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
S. N. Herzog and P. W. Michael,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 167-178,
März 2010
view abstract
Multiple field trials and nearly a decade of laboratory studies have demonstrated that shear stable multigrade hydraulic fluids can improve fuel economy. These studies have determined that fuel efficiency is dependent upon temperature, fluid viscosity and shear stability. This paper presents a viscosity classification system proposed by the National Fluid Power Association (NFPA) Fluids Technical Committee. This system is analogous to the SAE J300 viscosity classification system for engine oils. Under this new classification system, NFPA 32L-68 fluids will provide the low temperature viscosity properties of an ISO VG 32 hydraulic fluid and the high temperature viscosity properties of an ISO VG 68. In addition, fluids that meet the requirements of the proposed NFPA Energy Efficient classification system increase fuel economy and productivity while reducing CO2 emissions. A summary of field trial results and explanation of the proposed NFPA Energy Efficient viscosity classification system are provided.
Hydraulic Hybrid Transmission Design Considerations for Optimal Customer Satisfaction
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
A. Johansson and J.-C. Ossyra,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 369-380,
März 2010
view abstract
The key driver for vehicle hybrid technology development is fuel economy, contributing not only to significant life cycle cost reductions but also to important cut-downs in green house gas emissions. Over the years, many different concepts have been developed that improve fuel economy. The essence of the problem in development of modern hybrid transmissions, however, is to achieve fuel savings without compromising conventional drivers’ characteristics such as reliability, safety, productivity, driveability, comfort, serviceability etc. Parkers advanced series hydraulic hybrid transmission, RunWise, offers the highest fuel economy in class 8 refuse vehicles, with 30-50 % reduced fuel consumption compared to baseline vehicles. Instead of providing a choice between productivity and fuel savings, customer values such as driving comfort, increased productivity and fuel reduction have been part of the design requirements for the system with noticeable improvements compared to baseline vehicles. This paper aims to clarify how the RunWise hybrid transmission, on a system level, has been designed such that the hydraulic pump/motor units operate close to the peak of their performance, resulting in high efficiency through-out the complete operating range, and in turn how the characteristics of the pump/motor units enables the system to be designed the way it is.
Hydraulic Intelligent Instrument Based on the Double CPU Sharing RAM Technology
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Bingjing and H. Jianhai and Z. Jianmin,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 819-821,
April 2005
view abstract
Because of the great data stream and the high real-time control requirement of the hydraulic testing and controlling system, a kind of double CPU sharing RAM system based on dual-port RAM technology is introduced in this paper. It expounds the memory sharing technology, bus arbitration technique, hardware & software design and the communication protocols in detail. The technology is validated and implemented in the hydraulic intelligent instruments.
Hydraulic Manifold Hole Checking Using Real-coding Genetic Algorithm
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
P.K. Wong and T.P. Leung and LM.Tam,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 548-553,
April 2005
view abstract
This research is the first attempt to use Real-coding Genetic Algorithm (RGA) approach for physical interference checking of hydraulic manifold hole with wall thickness and drill cone consideration. Typical computer-aided technique for hydraulic manifold hole checking is the 3D constructive solid geometry method, which treats two holes as two entities, and checks them by Boolean pattern UNION. The disadvantage of this method is that it requires the user to convert the traditional 2D drawing into 3D. This operation is also very time consuming and takes up a lot of computer memory and storage space for the 3D drawing. Moreover, this model is not mathematical-based; it can only check whether the holes are open or short, but it cannot tell the user the minimum wall thickness between a pair of holes and drill cones. In practice, wall thickness is very important for hydraulic manifold design. To facilitate the design processes, an automatic system for this problem is therefore studied. RGA is an evolutionary algorithm to identify global maximum and minimum points of multivariable functions or optimal point in system equations without solving complex mathematical equations. In this paper, RGA calculates the nearest distance between two hole entities, says "d. If d is less than the minimum wall thickness, then the two holes interfere with each other. Otherwise, it passes. With iterative process, RGA can check all hole entities in the manifold block using one simple mathematical model. A prototype computer-aided manifold block design and hole checking system, written in C++ and running on an AutoCAD platform, has been built to implement the concept. The system can concurrently draw and record the locations and sizes of the holes in a 2D drawing. The data recorded can serves as the input variables of the mathematical models. Experimental results show the program actually shortens the checking process, and the CAD environment can be simplified from the traditional 3D to 2D.
HYDRAULIC-MECHANICAL ENERGY SAVING SYSTEM IN CRANES AND TRANSPORTATION EQUIPMENT
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
G. Buczak and A. Sobczyk,
2006,
volume 2,
pp. 641-648,
Juni 2006
view abstract
This paper presents the concept of energy saving system which base on possibility of using potential energy of machine
counterweight. As a base for this consideration, all-terrain mobile crane Jones was assumed. Necessary simulations
were done by use of Working Model software. For this machine boom mechanism work parameter were estimated
together with energy required to raise the boom. Hydraulic-mechanical energy saving system was proposed and system
parameters were assigned. Possible value of the energy which could be recovered was estimated and compared with
energy consumption of original boom raising mechanism. Analyses of system simulation results allowed formulating
conclusions and lying out further directions of research into proposed mobile crane energy saving system.
HYDRAULIC OIL FLOW WALL SHEAR EFFECT ON VALVE ACTUATOR FLOW FORCES
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
R. Yang,
2006, August 2006
view abstract
This paper presents results of a study regarding hydraulic oil flow viscous wall drag effect on flow induced forces
inside hydraulic valves using Computational Fluid Dynamics (CFD) simulations. Flow induced forces, also often
referred to as flow forces, are very important in valve design and optimization. A common way used in CFD
simulation to calculate flow forces is to integrate the pressure field, from CFD solutions, over related surface regions on
targeted valve component such as an actuator. However, in some cases, flow induced viscous wall drag forces on
valve actuators, caused by oil flow velocity near solid component surfaces due to fluid viscosity, can be very
significant. In this article, cases with different common valves used in mobile hydraulics will be studied, including
spool type valves and poppet valves. Method of estimating oil flow viscous wall drag force under different conditions
as well as how to use this force for better valve control will also be explored and discussed
Hydraulic Power Brakes with ABS for Tractors and Mobile Equipment Innovative Power Brake – Safely on track with ABS
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
A. Remmelmann and B. Völker and K. Tischler,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 489-496,
März 2010
view abstract
Today's mobile equipment market and especially the tractor market require higher transportation speeds. Influenced by this development the brake system of the vehicle becomes increasingly important. The main objective is to provide higher braking performance and to have features that improve the vehicle stability while braking. This paper describes a modular solution that addresses both tasks. First, increased brake performance that requires higher brake cylinder volumes can be solved with hydraulic power brakes that can work with nearly every available brake cylinder size. To address the second task this paper describes the technical solution of an hydraulic power brake system that offers full anti-lock brake functionality by combining a conventional hydraulic power brake with an anti-lock brake module widely used in the automotive industry. The system can be easily adapted to all kinds of mobile equipment e.g. tractors, wheel loaders or dumpers. Based on the system set up, the special features of the solution and its technical advantages will be explained. Finally the dynamic behaviour of the solution will be demonstrated by theoretical examinations with dynamic simulations as well as with laboratory examinations under different conditions. In addition to this, the results of vehicle tests on specific test tracks with this system set up will be presented.
Hydraulic proportional valves - evaluation of changes in performance characteristics for condition monitoring purposes
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
L. Laitinen and M. Pietola,
2004,
pp. 321-328,
Juni 2004
view abstract
In this article, the effect of aging on the characteristics of a hydraulic proportional valve is studied. The
valve used in this study was a directly operated, spool type proportional valve of nominal size 6.
Measurements were taken both from a new valve and a same-modeled but aged valve. The changes
observed in measurements, absolute difference values and trends alike, are analyzed and discussed
especially in terms of applicability to the on-line condition monitoring.
Some significant differences, e.g. 35% decline in pressure gain, were observed between the measurement
results of the studied valves. The results showed that some standard measurement methods could be the
basis for developing a condition monitoring system for the proportional valve. The boundary conditions
of the typical environment of the valve, such as lack of space and minimization of costs, were taken into
account when the conclusions were made.
Hydraulic Servo System With Mechanically Adjustable Compliance
Toshiyuki Hayase and Kazuhiro Ishizawa and Satoru Hayashi and Ikuro Iimura,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 168-175,
März 2002
view abstract
This paper deals with a hydraulic servo system with compliance control for the operation in an environment with frequent machine-human interaction. The compliance is mechanically adjusted in the present hydraulic system by changing the neutral position of the bridge valves between the full opening and the full closing states. The mathematical model of the system is first derived, and the static and the dynamic behavior of the system are investigated through numerical simulation. Since the present system exhibits a strong nonlinear characteristic in the operating condition of large compliance, a nonlinear controller is designed with the feedback linearization technique. In the operating condition of small compliance, on the other hand, a conventional linear control is applicable as usual hydraulic control systems. The performance of the present control system is investigated through both numerical simulation and experiment, justifying that the present hydraulic servo system continuously adapts its performance between a rigid positioning against disturbances and a compliant positioning to prevent damage to obstacles on the path.
Hydraulics of the Antarctic Station Neumayer III
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
S. Rotthäuser and H. Jagolski,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 61-74,
März 2010
view abstract
The paper describes the function and the theoretical background of the hydraulic lifting and control system of the polar station Neumayer III. The mayor task is the monitoring and controlling of structural stresses. For this purpose a simple mechanical model is developed to get these stress information out of level measurements. The methods of singularity function and matrix calculation were used. Respective the combination of shear and bending aspects in one equation has to be highlighted. Network technologies allow remote visualization and control via internet services. Using and developing open source software makes sure that the system will be maintainable for a long period. The crew at the station can be supported by an engineering team if necessary. The derivation of the used equations as well as the description of the mechanical and hydraulic components is described in this paper.
Hydraulic Switching Control With a Nonlinear Converter
5th MATHMOD Vienna
R. Scheidl and B. Manhartsgruber and H. Kogler,
2006,
view abstract
In this paper, the hydraulic analogy of the so called Buck Converter of power electronics is studied. It consists of a discrete inductivity, a capacity, and a valve. In our hydraulic Buck Converter, the capacity is realised by a standard gas spring hydraulic accumulator with a nonlinear behaviour and the inductivity by a hydraulic pipe which may exhibit complex wave propagation phenomena. The task to be solved here is to work out a reduced model for this converter configuration, which describes the essence of its behaviour, and, additionally to find the ranges in parameter space of the complex system for which this reduced model is valid. For small accumulator capacities, the reduced model exhibits a one dimensional invariant manifold in each switching state which characterises a slow dynamics of the system. The remaining part of the phase space is foliated by trajectories representing the fast dynamics of the reduced system. Approximate simple formulas describe both type of trajectories and the flow on them. With these results, the reduced system can be evaluated w.r.t. the technical requirements. In a second step the question is investigated, under which circumstances the disturbed system, i.e. the system taking into account the complex dynamics of wave propagation in the pipe, the finite capacity of the large accumulator, the finite switching time of the valves, and the dynamical properties of an attached hydraulic cylinder, is close to the reduced system. This is carried out by a numerical analysis.
Hydraulic System For Steer-By-Wire (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
R. Voženílek and M. Malý and P. Brabec,
2008,
pp. 222-229,
September 2008
view abstract
The design of the directional control system represents one of the most important parts of automobiles and vehicles in general. Just as with automobiles in general, the design of the directional control has developed and improved over time but has to continue to perform the same function: to keep the vehicle moving in a certain direction or change its direction purposefully. The directional control system continues to evolve and in the future, the traditional mechanical connection between the steering wheel and the wheels is likely to be eliminated and replaced with another system enabling higher variability in directional dynamics.
The Department of Engines and Vehicles at Technical University of Liberec has developed a design of testing equipment for directional control system testing. The objective of the newly designed equipment is to incorporate a wheel with a real tire and a resilient bearing of the axle components.
At present, properties of the hydraulic circuit consisting of two double-acting engines with a unilateral piston rod (32 mm/22 mm dia.) and two proportional valves D1FP(Parker) with the rate of flow as high as 3 dm3.min-1 at the pressure gradient of 3.5 MPa, located on a frame which contains a pressure valve, a relief valve and other accessories, are being studied. The D1FP proportional valve has a built-in PID regulator.
The experimental laboratory establishment has already carried out some measurements. The behaviour of the system has been monitored at varied rate of flow (for 10%, 25%, 50%, 75% and 100% of proportional valve opening). This paper evidences pressure response to a sudden change in the settings.
Hydraulic Systems for Deep-Sea Applications
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
H. Fischer and T. Steigerwald and M. Godzik,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 509-522,
März 2010
view abstract
The growth in global demand for raw materials, such as petroleum, natural gas, and minerals, with simultaneously decreasing reservoirs makes the development of new production areas necessary and economically interesting. To develop new production areas on the seafloor, deep-sea crawlers will be needed in the future. Within the scope of the "ISUP lighthouse project" funded by the German Federal Government (BMWI), Rexroth is developing a hydraulic system for an underwater work unit. Hydraulics can show their full strength in this application: they are powerful, compact, precise, and intelligent. Rexroth has risen to the enormous challenges presented here, such as high external pressure (up to 400 bar), seawater environment, abrasive particles and maintenance-free operation for a period of several years.
Hydraulic Systems in the Context of the New EU Machinery Directive (2006/42/EC)
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
E. Weishaupt,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 139-152,
März 2010
view abstract
This paper shows how hydraulic systems are to be classified and dealt with in the context of European safety standards. This paper presents an interpretation of the new Machinery Directive from the point of view of a hydraulic equipment and systems manufacturer, and as such is not intended to be exhaustive nor is it designed to serve as a substitute for the product manager acquiring detailed knowledge of this topic.
Hydraulic Systems Sizing Using Bond Graphs
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Derkaoui and S. Scavarda and É. Bideaux,
2004,
pp. 93-103,
Juni 2004
view abstract
This paper presents a dimensioning approach based on an inverse method using dynamic and energetic
criteria. System inversion techniques and Bond Graph representations developed by Roger Fotsu
Ngwompo and Serge Scavarda [12] are used here to extend the methodology to the dimensioning of
mechatronic systems including distributed parameter components.
In the design of hydraulic circuits, the type of components and the way they are interconnected to generate
a required sequence of actions by a fluid power system is one important aspect. In this paper however the
attention will be given more to the “distributed parameters point of view” for the pipe linking different
components, the goal is to size some components of the system to make possible the application of a
specification defined as a trajectory to be followed by the hydraulic actuator.
Hydro-Mechanical Control of a Self-Energising Hydraulic Brake
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
J. Ewald and M. Kühnlein and H. Murrenhoff and M. Liermann,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 337-348,
März 2010
view abstract
The Self-energising Electro-Hydraulic Brake (SEHB) was originally developed for railway applications. Based on the same principle, a concept for road vehicles has been developed at the IFAS of RWTH Aachen University.
In a first step, this paper discusses a possible braking system for passenger cars, using the selfenergising concept. It meets the requirements of a braking system with capabilities for hybrid vehicles. The SEHB allows independent operation from the combustion engine and a hydraulic feedback of the braking torque facilitates electronically controlled brake blending. A design study for commercial vehicles shows the compact design of a SEHB calliper for a very high brake torque as it is needed for the powered axle of an articulated lorry. From the aspect of security a fall back level operating without electricity is needed. Even for this case the brake torque control can be ensured by a hydro-mechanical control. As published in previous papers, this functionality can be realised by a purely hydraulic control.
Hydro-Mechanical Model of Electro-Hydraulic Servovalve Based on Bond Graph
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
Y. Xu and E. Bideaux and S. Sesmat and L. Sidhom and X. Brun,
2010,
volume 1,
pp. 271-281,
Juni 2010
view abstract
Bond Graph, as a graphical modeling language, can represent various physical domains in a unified form. This paper
deals with the establishment of a Bond Graph model of an electro-hydraulic servovalve which consists of a torque
motor, a cantilever feedback spring, and two hydraulic stages, one with a nozzle/flapper system and the other with a
spool valve. The entire model can be divided into a hydraulic and a mechanical part which are connected by 2-port
modulated R-elements representing orifice pressure drop and jet force phenomena, and TF-elements coupling the
mechanical and hydraulic power. The Bond Graph model of whole system is then presented. Finally, using AMESim on
which a model was created based on the established Bond Graph, simulation results are compared with the
experimental measurements.
Hydrostatically discharged commutation unit and it’s impact on axial pump’s performance
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
L. Osiecki,
2006,
pp. 150-158,
Mai 2006
view abstract
Port plate commutation unit is responsible for more than 50% of all energetic losses in the
pump. The main sources of such a loss are: leakage through the clearance between fixed port plate
and rotating cylinder block, friction between those elements, pressure drop caused by oil flow through
the windows and volumetric losses caused by oil compressibility in pump’s dead volume. The
clearance height must be kept low under varying working conditions. The only way to obtain it is to
exert an axial force on the plate or cylinder block to keep them in close contact. The value of that axial
force must also grow proportionally to growing pressure in the T port. Such a force combined with
viscous friction in oil, which fills the clearance, results in considerable torque loss. Reduction of axial
force may however lead to rise of clearance height and result in excessive leakage and plummeting
volumetric efficiency.
The newly invented, cam-driven commutation unit allows to fix the height of clearance between
working parts and to discharge all elements of that unit (sleeves and cam) from hydrostatic forces.
The result is significant drop of torque loss combined with constant internal leakage generated by the
commutation unit. What’s more the new unit reduces also the pressure drop thanks to fixed cylinder
barrel and allows to build an axial pump with dead volume less than 10% of it’s stroke volume
(compared to 40÷50% in best axial pumps produced now by leading manufacturers). The paper shows
possible advantages of such a feature.
The new constant displacement axial pump (marked as PWK pump)was built and tested
in Department’s laboratory. The paper shows results of the tests compared with tests of three
port plate pumps ( A, B and C) made by world’s leading manufacturers. Comparison of
volumetric losses shows that port plate pumps A, B and C reach higher results in lowpressure
area. The main reason for that is number of pistons: pump PWK has 14 of them,
pumps A,B and C only 9 or 7. PWK pump shows its advantage in the high-pressure area.
Thanks to constant height of the clearance between elements of the mechanism efficiency
graph has a perfect linear shape and pump can reach very high pressure exceeding 500 bar.
Values of torque efficiency reached by the same four pumps show that thanks to full
discharge of commutation unit parts from hydrostatic forces and cylinder block which doesn’t
rotate the new pump’s torque efficiency has no equivalent in the whole range of working
pressure.
The final comparison shows changes of pump’s overall efficiency, which combines both
volumetric and torque losses in each pump. The PWK pump reaches the highest value – above 93%. It
is also the only pump capable of working under very high pressure – up to 550 bar. All measurements
were made using the same test stand and equipment. The production of PWK pumps (two sizes) started
now in Polish company “Hydrotor” S.A.
Hydrostatic Systems of Wind Power-Stations (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
L. Němec,
2008,
pp. 49-56,
September 2008
view abstract
1. Renewable resources of energy
2. Wind mills
3.Comparison of hydraulic and electric systems of wind mills – advantages and disadvantages
4. Hydraulic pitch drives and yaw drives of wind mills
5. Planetary gearboxes of wind mills
6. System of wind mills with variable gearboxes and synchronous generators
Hydrostatic Transmission as a Part of Closed Loop Control
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
M. Ijas and E. Mäkinen and P. Ijäs and M. Vilenius,
2007,
volume 3,
pp. 151-160,
Mai 2007
view abstract
The control of a hydrostatic transmission (HST) is usually open loop control. There are lots of studies in which different control strategies of HST are considered. Usually, the
aims of these studies are the total efficiency of the HST or the total efficiency of a machine. In this paper the feasibility of the HST as a part of a closed loop position
control of a winch is studied.
The studied hydraulic Self-Contained Winch of Rolls-Royce Oy Ab. The Self-Contained Winch is a new type intelligent winch drive system equipped with the HST and an electronic controller. The winch with the HST is especially suitable for mooring and anchoring use. The new electronic controller makes it possible to develop and utilized different sophisticated rope control strategies. It is possible to control a rope force by using working pressure as a controlled parameter (force control or autotension). It is also possible to control a rope speed or a rope position using the closed loop control. In
this study the closed loop position control was experimental studied using a winch bench.
The Self-Contained Winch was installed to the test bench, which was connected a vertical moving mass with a rope. The mass used of the test bench was 6800kg.
IBIS - Advanced Multi-functional Machinery for Outdoor Applications
Proc. of The 18th International Conference on Hydraulics and Pneumatics, Prague, September 30 – October 1, 2003
R. Rahmfeld, M. Ivantysynova, J. Weber,
2003,
view abstract
The aim of the “Advanced Multi-functional machinery for Outdoor Application”
(IBIS) EC project is to develop basic technologies for a new generation of construction machine,
based on the concept of multi-application tool-carriers, automatic motion control of
the boom using innovative hydraulic actuators and on-board diagnostics. The project addresses
the needs for more eco-efficient and environmental friendly, safer and user friendlier
machines. Due to reduced fuel consumption and less pollution the developments will significantly
reduce the exploitation of primary energy resources. By developing onboard condition
monitoring including diagnostic and prognostic methods for generic hydraulic systems in
combination with sophisticated automatic motion control of the machine a highly improved
operability and worker’s safety will be achieved.
This paper summarizes the activities within the IBIS project funded by the EC. The main focus
lies on the new innovative hydraulic actuator technologies for future mobile machine working
hydraulics and diagnostic as well as prognostic methods for hydraulic systems of mobile machines
by using minimum sensorial effort.
Keywords: multi-functional boom structures, new innovative hydraulic actuators, diagnostics,
motion control, displacement control, linear actuator, working hydraulics, mobile machines
IDENTIFICATION OF MATHEMATICAL MODEL OF THE VEHICLE WATER HYDRAULIC DRIVE SYSTEM
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
A. Gawlik and A. Sobczyk,
2006,
volume 1,
pp. 275-283,
Juni 2006
view abstract
The main application field of water hydraulic systems with water as a pressure fluid is stationary devices of the power
of order of magnitude or so kilowatts. With regard to the possibility of realization both linear and rotary motions by
available components of new generation water hydraulics, it seems natural to extend the application of these systems to
mobile machines. Within the scheme of further research work into new generation water hydraulic systems in Fluid
Power Laboratory of Cracow University of Technology, the research vehicle, propelled by water hydraulic system was
built. It is a small cart in which the system of batteries, electric motors and worm gears were replaced by hydrostatic
drive with two high-torque, low-speed motors, which drive cart wheels, directly. The axial piston pump supplying the
hydraulic system is propelled by one-cylinder engine. The vehicle velocity at constant engine rpm is regulated by
proportional flow control valve controlled by a voltage signal. The paper presents selected data of road condition
which enable verification of the primary assumptions and parameterization of the mathematical model of the cart drive
system. The primary tests show the suitability of water hydraulic new generation to driving mechanism in such small
vehicle.
Identification of pneumatic artificial muscle manipulators by a MGA-based nonlinear NARX fuzzy model
H. P. H. Anh and K. K. Ahn,
In Mechatronics,
2009,
volume 19,
pp. 106-133,
Februar 2009
view abstract
This study investigates the technique of modeling and identification of a new dynamic NARX fuzzy model by means of genetic algorithms. In conventional identification techniques, there are difficulties such as poor knowledge of the process, inaccurate process or complexity of the resulting mathematical model.
All these factors deteriorate the identification performance when dealing with dynamic nonlinear industrial processes. To overcome these difficulties, this paper proposes a novel approach by using a modified genetic algorithm (MGA) combined with the predictive capability of nonlinear ARX (NARX) model for generating the dynamic NARX Takagi-Sugeno (TS) fuzzy model. The MGA algorithm processes the experimental
input-output training data from the real system and optimizes the NARX fuzzy model parameters.
This is referred to as fuzzy identification, which automatically generates the appropriate fuzzy if-then rules to characterize the dynamic nonlinear features of the real plant. The prototype pneumatic artificial muscle (PAM) manipulator, being a typical nonlinear and time-varying system, is used as a test system for this novel approach. This result shows that, with this MGA-based modeling and identification, the novel NARX fuzzy model identification approach to the PAM manipulator achieved highly outstanding
performance and high precision as well. The accuracy of the proposed MGA-based NARX fuzzy model proves excellent in comparison with the MGA-based TS fuzzy model and the conventional GA-based TS fuzzy model.
Identifying a Nonlinear Dynamic System with Partially Recurrent Neural Networks - Feasibility Study and Issues on Error Accumulation Problems
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
X. Ping and R. Burton and C. Sargent,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 13-19,
November 1997
view abstract
Conventional methods of modeling transient behaviour of an actual system involve developing mathematical equations based on the observed physical relationships among the associated
components and engineering practical considerations. In many cases, however, the presence of nonlinearities in actual systems and the difficulties in accurately measuring parameters have restricted the interpretation of the modeling results to specific operating points and or with
limited modeling accuracy. An alternate is to establish the mathematical relationships of a system using a system identification approach based on input-output observations. Neural networks show the potential of establishing these mathematical relationships, because of their proven capability of approximating nonlinear functions. This study investigates the use of partially recurrent neural networks to identify transient responses of certain nonlinear systems,
and presents the results of a theoretical study which carefully examines the modeling error behaviour. The results of this study have established the potential and, indeed, limitations to this neural modeIing approach. The effect of error accumulation through feedback paths of dynamic models on the modeling accuracy is briefly discussed with an illustrative example.
IHT Controlled Serial Hydraulic Hybrid Passenger Cars
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
G.E.M. Vael and P.A.J. Achten,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 393-405,
März 2010
view abstract
The 'hydrid' is a fairly new serial hydraulic hybrid drive line concept. The term ‘hydrid’ is used for hydraulic drive lines in which four constant displacement Floating Cup (FC) wheel drive units are pressure controlled by means of two Innas Hydraulic Transformers (IHT). It has been shown in earlier publications that a four wheel drive hydrid drive line with wheel hub motors realises reductions of fuel consumption and CO2 emission of more than 50 %. In modern passenger cars, there is a large gap between - on one hand - the engine power and wheel torque necessary to fulfil the maximum performance requirements and - on the other hand - the quite modest power and torque demand in normal, every-day use. This gap is the main reason for the rather bad energy efficiency of modern passenger cars. Contrary to other hybrid concepts, the hydrid can bridge this gap and achieve large reductions without compromising performance. This paper shows how the use of floating cup technology, the pressure amplification capability of the Innas hydraulic transformer (IHT) and a four wheel drive line topology, come together to realise this. After that a serial hydrid front wheel drive line is presented, which can realise similar reductions but uses only one IHT and two FC drive units, which attach to the front axle differential. Finally, some ideas for other serial hydrid drive lines are given.
Impact Control in Hydraulic Actuators
P. Sekhavat and Q. Wu and N. Sepehri,
In Journal of Dynamic Systems, Measurement, and Control,
2005,
volume 127,
pp. 197-205,
Juni 2005
view abstract
Every manipulator contact task that begins with a transition from free motion to constraint motion may exhibit impacts that could drive the system unstable. Stabilization of manipulators during this transition is, therefore, an important issue in contact task control design. This paper presents a discontinuous controller to regulate the transition mode in hydraulic actuators. The controller, upon sensing a nonzero force, positions the actuator at the location where the force was sensed, thus, exerting minimal force on a nonmoving environment. The scheme does not require force or velocity feedback as they are difficult to measure throughout the short transition phase. Also, no knowledge about the environment or hydraulic parameters is required for control action. Due to the discontinuity of the control law, the control system is nonsmooth. First, the existence, continuation and uniqueness of Filippov's solution to the system are proven. Next, the extension of Lyapunov stability theory to nonsmooth systems is employed to guarantee the global asymptotic convergence of the entire system's state towards the equilibrium point. Complete dynamic characteristics of hydraulic functions and Hertz-type contact model are included in the stability analysis. Experiments are conducted to verify the practicality and effectiveness of the proposed controller. They include actuator collisions with hard and soft environments and with various approach velocities.
Impact of cylinder block-shaft coupling design on behaviour of cylinder block-valve plate sealing gap interface
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
K. Klein,
2008,
pp. 176-183,
September 2008
view abstract
Sealing gaps between swash plate and slipper, piston and bushing or cylinder block and valve plate of axial piston pump are key design elements influencing an energy dissipation and efficiency of displacement machine. Many publications deal with a research of sealing and bearing gaps in axial piston machines, but an information especially about cylinder block-shaft coupling design and its impact on hydraulic conditions of cylinder block-valve plate interface are rare.
This paper presents numerical simulations of cylinder block-shaft assembly of axial piston pump (Figure 1) using finite element method (FEM). The main goal of the simulations was to build a numerical model and analyze behaviour of the cylinder block-shaft assembly; when coupling is realized by splines. To be able to define an impact of performed design changes several numerical models were created under different coupling design considerations.
Finally, the simulations were performed in ANSYS environment. Obtained results are evaluated and presented in a graphical form. This investigation indicates that the coupling design (cylinder block hub-shaft stiffness, splines crowning feature) can considerably influence hydraulic conditions of the cylinder block-valve plate sealing gap interface.
Impedance Control of Redundant Manipulators
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
A. Muhammad and M. Vilenius,
2010,
volume 1,
pp. 153-163,
Juni 2010
view abstract
This paper is the summary of the thesis work to investigate the effects of kinematic redundancy on the dynamic
manipulability of the manipulators, and to implement and study the impedance control for the kinematically redundant
manipulators. The theoretical discussions and results regarding the effects of redundancy on the dynamic performance
of manipulators have been kept general without references to any particular manipulator. The purpose is to keep the
findings useful for other developments and continue the research and discussion process on a wider scale. For the
numerical analysis and experimental verification of the results, a Water Hydraulic MANipulator (WHMAN) has been
used. The manipulator has been designed to carry out remote handling operations inside the divertor region of
International Thermonuclear Experimental Reactor (ITER). The goal is to find and suggest the suitable posture and
trajectories for the manipulator for a given task.
Implementation of Rosenbrock Integration Algorithm with Adaptive Step Size Control in Time-Domain Simulation of Fluid Power Systems
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
T. J. Käppi and A. U. Ellman and R. Piché,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 35-40,
November 1998
view abstract
Numerical simulation models of fluid power systems typically have a large scale of different time constants and so can be considered as numerically stiff systems.
The Rosenbrock method is a differential equation integration
algorithm with suitable accuracy and stability properties. In this paper the implementation of the Rosenbrock method as part of a time-domain fluid power system simulation package is presented.
Adaptive time step size control makes it possible to achieve an optimal computational effort with controllable integration error based on user-defined error tolerance.
Computation of examples show considerable improvement in accuracy and computational speed over the previously used integration method.
IMPLEMENTATION OF SINGLE FEEDBACK CONTROL LOOP FOR CONSTANT POWER REGULATED SWASH PLATE AXIAL PISTON PUMPS
M. K. B. Khalil and V. D. Yurkevich and J. Svoboda and R. B. Bhat,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 27-36,
Dezember 2002
view abstract
Variable displacement pumps are often used in both industrial applications and mobile hydraulic machinery. In such
pumps, flow rate is dictated by the system requirements. Mathematical model has been previously developed to simulate
the dynamic performance of the electrically controlled constant power regulated swash plate axial piston pump with
conical cylinder blocks. The pump is currently equipped with a double negative feedback control loop with an inner
control loop to control the position of proportional valve using PID controller. Consequently, the proportional valve
distributes the control pressure across the two sides of a control piston that is mechanically attached to the pump swash
plate in order to change the pump flow rate. The outer control loop is used to control the pump flow rate in accordance
with the system pressure change in order to keep the constant power operation using PD controller. For the convenience
of pump constant power operation, PD controller is tuned to keep limited power shocks on the pump drive motor during
the transient periods. The selected PD parameters result in relatively reduced settling time. Consequently swash plate
steady state vibration appears.
Purpose of this paper is to investigate features of the pump performance in view of an alternative control scheme.
Counting on the relatively good open loop static characteristics of the proportional valve, a control scheme with a single control feedback loop is proposed to simplify the currently used control scheme. Using such single feedback control loop reduces the pump production cost and leads to have less responsive system that suppresses the steady state vibration of the swash plate. Simulation results are verified experimentally and qualitatively compared with the results when
the original control scheme is used. Results are presented and discussed.
Improved Functionalities and Energy Saving Potential on Mobile Machines Combining Electronics with Flow Sharing Valve and Variable Displacement Pump
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
A. Lettini and M. Havermann and M. Guidetti and A. Fornaciari,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 103-114,
März 2010
view abstract
This paper presents an electro-hydraulic load sensing system for a mobile machine derived from an evolution of a hydro-mechanical load sensing circuit. A variable displacement piston pump with a new electronic pressure control system (PEC) has been developed by Casappa and combined with a flowsharing valve from Walvoil. The system is equipped with pressure sensors on the pump outlet and load sensing lines; their signals are fed into the electronic pressure control of the pump constituting a closed-loop control circuit, in order to realize an electronic load sensing control. In a further step, the pump is equipped with an additional swashplate angular sensor to monitor the effective pump displacement (PECA): the pump displacement signal is introduced into the electronic control unit as a further feedback signal. In this way, a torque control becomes possible. The whole system was mounted on a medium-size excavator. Some field tests were conducted in order to check its potential advantages and to compare the new system performance to a conventional hydro-mechanical load-sensing circuit.
IMPROVED LOSS MODELING OF HYDROSTATIC UNITS – REQUIREMENT FOR PRECISE SIMULATION OF MOBILE WORKING MACHINE DRIVELINES
Proceedings of IMECE07, 2007 ASME International Mechanical Engineering Congress and Exposition, November 11-15, 2007, Seattle, Washington, USA
T. Kohmäscher, R. Rahmfeld, H. Murrenhoff, E. Skirde,
2007,
view abstract
The aim of this paper is to analyze different loss modeling
methods for hydrostatic pumps and motors as an input for
dynamic system simulation. Using dynamic simulation in an
early design phase allows for optimization of driveline,
driveline control and working hydraulic within several
operating conditions. Using precise loss modeling methods
enables prediction of energy consumption and energy losses
over various duty cycles. Rising energy costs, enhanced
government guidelines and increased environmental awareness
require more efficient drive concepts especially in mobile
working machines. Because of the complex machine structure
with numerous hydraulic power consumers, like driveline,
working, steering and braking hydraulic, dynamic system
simulation is a need in the early design phase.
This paper focuses on partial and full hydrostatic
drivelines of mobile working machines which operate mostly
on basis of a closed circuit hydrostatic transmission.
Hydrostatic power lines connect pump and motor directly
without additional losses because of valves or system
characteristics. Therefore losses in the hydrostatic units have
major relevance for the loss behavior of the hydrostatic
transmission. The use of precise loss models is essential for
analyzing hydrostatic transmission by means of dynamic
system simulation.
In the scope of this paper, one physical-empiric and four
mathematical loss modeling methods are introduced,
investigated and compared. Finally, the most promising
modeling method is used for the simulation of a state of the art hydrostatic transmission.
Improved Performance of Over Centre Valve System Utilizing Negative Flow Force Characteristics
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
P. Pedersen and T. O. Andersen and M. R. Hansen and F. Conrad,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 109-112,
April 2005
view abstract
In this paper the stability problems often encountered in hydraulic systems with over-centre valves and pressure compensated directional control valves are considered. A parameter study carried out in previous work clearly indicates that negative flow forces (forces that try to Open the valve rather than close it during operation) at the poppet seat orifice of the over-centre valve seems to reduce the above mentioned stability problems. Subsequently, work has also been done along the lines of shaping the flow force characteristic of the poppet seat orifice by adding a nm to the geometry.
The main purpose of this paper has been to add a mathematical analysis combining linearisation and stability analysis, which clearly shows that a beneficial effect can be expected in a wide variety of mobile hydraulic applications.
Improved Tracking Control of Hydraulic Systems
Bora Eryilmaz and Bruce H. Wilson,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 457-462,
September 2001
view abstract
Tracking control for hydraulic systems is a key system requirement, as these devices must often follow prescribed motions. Tracking control of hydraulic systems has been approached using both linear and nonlinear control laws. The latter provides improved performance, but at the expense of additional sensors. Further, the control laws often employ hydraulic fluid bulk modulus—a difficult-to-characterize quantity—as a parameter. To overcome these difficulties, we have developed a control design procedure that requires no additional sensors and is robust to variations in the bulk modulus. A dual approach of singular perturbation theory and Lyapunov techniques form the basis for the procedure. For the cases of a small-amplitude sinusoidal input and large-amplitude polynomial input, a candidate system achieved good tracking performance and exhibited outstanding robustness. The ability to accomplish good tracking in a robust manner with no additional sensors provides advantages over other nonlinear tracking algorithms.
Improvement in feedback signal quality for water hydraulic manipulator
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
A. Muhammad and J. Mattila and T. Virvalo and M. Vilenius,
2008,
pp. 135-148,
September 2008
view abstract
The performance of hydraulic positioning servo systems is very often limited by the poor dynamics of the valve and the actuator. The use of velocity and acceleration as feedback signals can significantly improve the dynamic response of such system. However, this improvement depends on the quality of the feedback signal. In this paper we investigate the possible improvement in the quality of the feedback signal and its effect on the dynamic performance of the system. A step-by-step approach is followed starting from a single hydraulic cylinder and then extending the findings to a 5-DOF water hydraulic manipulator.
IMPROVEMENT OF POSITION CONTROL PERFORMANCE FOR A HYDRAULIC ROTARY ACTUATOR SYSTEM USING STATE FEEDBACK NEURAL NETWORK CONTROLLER WITH DITHER SIGNALS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0500-4,
H. Katoh and T. Nishiumi,
2006,
volume 2,
pp. 475-484,
Juni 2006
view abstract
The purpose of this study is to develop a precise angular position control system of the hydraulic rotary actuator.
However, it is generally not easy to acquire high positioning accuracy in hydraulic servo control systems, since they
have an intense non-linearity, such as dead zone, which is originally caused by the leakage and friction. It is
considered that the Neural Network compensator is one of the available options to get over the inherent problem.
This paper deals with the effect of dither signals on the positioning performance in the hydraulic rotary actuator
system with a state feedback Neural Network. At first, suitable parameters of dither signals are investigated. And
then, it is clarified that the application of the dither signals to the Neural Network control system improves the
positioning accuracy by accompanying the assistance of the Neural Network capability by experimental results.
IMPROVEMENT OF THE OPERATING CHARACTERISTICS OF MARINE LOW PRESSURE HYDRAULIC MACHINES
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
B. Kutter and D. G. Feldmann,
2000,
pp. 383-395,
September 2000
view abstract
The subject of the presented research project is the exact knowledge about the parameters influencing the operating
characteristics and limiting the maximum power of low pressure hydraulic vane type machines, used as
drives for ship-deck machinery, to obtain a full utilisation of the potential of these motor type, and the intera ction
between biodegradable hydraulic fluids and hydrostatic units of the motors. To improve the operating characteristics
of this motor type, several measures, like the application of friction- and wear-reducing coatings as
well as the fitting of synthetic or ceramic insets at the highly stressed contact areas shall be evaluated.
The state of the art, concerning the influence of geometrical and physical parameters and the fluids properties
on the total efficiency of hydrostatic motors is constrained on fast-moving devices or equations of general validity.
For that reason a mathematical model of a low-pressure, slow-moving, high torque vane type motor was
developed for the determination of volumetric and hydraulic-mechanical power dissipations.
Knowledge about the behaviour of biodegradable hydraulic fluids, their influence on component wear and energetic
efficiency of the motor and the change of fluid-characteristics and -performance under the special conditions
of a ship-deck machine was obtained by bench-tests.
Improvements of Quickness in High Speed On-Off Valve
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Tianjing and H. Jin-ming,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 501-505,
April 2005
view abstract
High speed on-off valve is mass-produced components for electrohydraulic servo mechanisms. Quality of a servomechanism depends on the valve-dynamics and it is important for valves to respond as quick as possible. Main delay of a valve is resulted usually from the time-constant of solenoid-inductance. It is compensated easily by energize the solenoid with a high-voltage over-excitation circuit. However more quick operation is prevented from the eddy-current in the magnetic circuit .It interferes to permeate magnetic-flux into armature. This paper clarifies the effect of eddy current on the switching speed of on-off solenoid by measuring the transient characteristics of the electric current and magnetic flux-flow, and next by calculating transient flux-flow on the process of permeating into the armature with the aid of newly-programmed FEM analysis. The author applied C2051 microcomputer controller, devised a new generator for PWM signal, thus also improved the quickness of the valve. Over-excitation energizing and low-conductive material shorten the delay of a switching -solenoid valve.
Improving and Appraising on Training Algorithm of Neural Network in Soft Measurement of Dynamic Flow
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
W. Yiqun and T. Yong and J. Wanlu and W. Hongyan,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 32-36,
April 2005
view abstract
To solve the measurement of dynamic flow in hydraulic servo Systems by applying neural network is an important work in the field. The difficulty is the improving on the training algorithm. First of all, the performance of the training algorithm of neural network was sum-up and advanced. Then output weight optimization-hidden weight optimization, fusing and adaptive alternation algorithms were put forward respectively. Finally, their performances are validated and appraised through experimentations. The research work is very significative to the soft measurement technology of dynamic flow.
Improving Characteristics of On/off Solenoid Valves
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
J. Mikkola and V. Ahola and T. Lauttamus and M. Luomaranta et al.,
2007,
volume 3,
pp. 343-353,
Mai 2007
view abstract
This paper studies simple measures to reduce response times of commercial directly operated solenoid valves. Two directly operated spool type solenoid valves, nominal sizes 6 and 4, and one seat type screw-in cartridge valve are studied. The main issue is that due to the time constant of typical coil, the current rises slowly with the nominal voltage and causes delay in valve opening. This can be overcome by using a short pulse
of higher voltage to the coil. This is achieved by using a booster circuit. Also the structure of the valves is modified by eliminating the springs in the valve and by using
4/3 valves as 2/2 valves in double flow configuration. The seat type screw-in cartridge valve is used only with the booster circuit. Experimental results show an improvement
of 50-70 percent in response times. Also the energy consumption in average use reduces and maximum flow capacity improves in the spool valves. With the seat type screw-in cartridge valve mainly the response time improves because the structure of the valve remains original.
Improving characteristics of switching hydraulic system based on high-speed on/off valves
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
F. Wang and L. Gu,
2010,
pp. 99-111,
September 2010
view abstract
Switching hydraulic techniques have been greatly developed due to lower throttling losses, intelligent control and low cost. The main benefits of the Pulse Width Modulation (PWM) switching technique are continuous output and simple hydraulic hardware. The biggest challenge of this switching technique is the development of extremely fast, reliable and energy efficient on/off valves. The slow response of the valves aggravates hydraulic fluctuation greatly.
Therefore in this paper, the hydraulic fluctuation which is caused by the switching of high-speed on/off valve is studied. The case studied is a hydraulic motor rotary speed control system using high-speed on/off valves. Hydraulic fluctuation occurs as the hydraulic motor is periodically accelerated and decelerated. Other than adding a hydraulic accumulator or hydraulic damper to attenuate the fluctuation, this paper seeks the reason why fluctuation occurs and the ways to attenuate it. It is shown that fluctuation is related to many parameters such as switching frequency, switching chamber volume, moment of inertia on the motor shaft, viscous friction and so on. The study is conducted with various parameters to evaluate the influence of proposed parameters on the fluctuation. Results show that fluctuation can be attenuated greatly through the proper design of those parameters.
Improving efficiency in a linear cyclic motion
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
S. Haikio and K. Huhtala and M. Vilenius and J. Makitalo,
2006,
pp. 15-29,
September 2006
view abstract
This paper deals with the energy consumption of the double-acting hydraulic cylinder. The main goal is to find out the method to maximize the efficiency of the hydraulic punching machine. There is presented a few alternatives to realize the system. The alternatives are analyzed by means of simulations with verified models.
The efficiency of the power unit has remarkable effect to the whole system. Variable pumps give flexibilities to save energy, but they are expensive and the control response is slow. The fixed pumps are cheaper, but there are some problems with energy efficiency on partial loads. The compressibility of the fluid also seems to be very remarkable to system characteristics.
According to the results the hydraulic supply power can be decreased 50% in the punching machine by means of the two pressure level system.
Improving Energy Utilization in Hydraulic Booms - What It Is All about
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Virvalo and W. Sun,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 55-65,
April 2005
view abstract
Energy utilization is quite poor in hydraulic booms. Modern mobile machines load sensing hydraulics is used. Because hydraulic booms are multi degree-of-freedom mechanisms, it is very challenging task to improve energy utilization in hydraulic boom applications. Energy consumption is estimated in a selected work cycle by simulations. Different possible methods to regenerate energy in an example boom are presented. A method to cross utilize different DOFs is proposed. Comparison between load sensing and proposed method is done. Simulations show quite promising results.
IMPROVING GAS DYNAMIC MODELS FOR PNEUMATIC SYSTEMS
S. de las Heras,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 47-56,
November 2003
view abstract
The present paper deals with the improvement to modelling of pneumatic systems. The thermal air process inside
the pneumatic chambers is modelled without using the polytrophic exponent to relate the pressure-density relationship.
The model takes into account the real gases behaviour and the thermal constant time for estimating heat transfer. The
polytrophic exponent is used only for adjusting the data and to improve the understanding of the system. The validity of
this method is demonstrated by experiments.
IMPROVING THE DYNAMIC BEHAVIOUR OF AXIAL PISTON PUMPS BY MEANS OF A GENERIC SIMULATION APPROACH
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
A. Wohlers and M. Meuser and H. Murrenhoff,
2008,
pp. 265-272,
Juli 2008
view abstract
The dynamic behaviour of hydraulic pumps is one of the most determining factors for applications in the field of mobile
hydraulics. Because of the inherent complexity of the physical phenomena involved, an economically justifiable
optimization based on an experimental set-up can often only be fashioned for existing pump geometries, while
concessions regarding the flexibility of the set-up have to be made. Designing a generic simulation model for the entire
pump thus is a necessary step toward the application of virtual prototyping in the development process of hydraulic
displacement units. In this paper, a generic simulation approach will be presented to study the dynamics of axial piston
pumps. One part of the simulation is the multi-body model of the axial piston pump designed in MSC.ADAMS. This
way, the kinematics of the pump as well as resulting kinetic forces are represented. The forces at each tribological
contact are applied to the model on the basis of characteristic diagrams. Using the information of the piston
displacements as an output of the mechanical simulation, pressures at each piston can be calculated in a hydraulic
simulation model, designed with DSHplus. Also, the hydraulic actuator at the swash plate is integrated into the
hydraulic model. Furthermore, a closed loop controller is used for piloting the supply valve of the actuator. The generic
simulation structure allows for variation of geometric pump design, hydraulic circuit and controller.
Using this generic simulation tool, the influence of several parameters in design, hydraulics and control on the dynamic
behaviour of an axial piston pump can be analysed. This paper presents results of this simulation, while it also shows
the impact of disturbance variables on the control loop.
Independent force control of pneumatic McKibben actuators using the multiplexing technique
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
V. Jouppila and A. Ellman,
2007,
pp. 331-347,
September 2007
view abstract
Traditionally in fluid power systems, each actuator is provided with an individual control valve that is often quite an expensive and weighty component. In multiplexed control, a single control valve is shared among a number of actuators providing cost and weight savings. In this study, the multiplexing is carried out with one pressure regulator and several high-speed on/off valves. It has been proven that multiplexed force control of pneumatic muscles is a good option for applications where multiple actuators have similar tasks with low dynamics [9].
In this paper, the possibility of controlling the forces of the pneumatic McKibben actuators individually with a multiplexing control method is studied. The characteristics of the actuator with low friction and hermetical structure enable its use especially in force control applications. The actuator can maintain its pressure and thus the generated force for a relatively long time after it is disconnected from the pressure line. This provides a possibility to increase the time between the muscle actuations in the multiplexed control cycle. During this gap period, the pressure regulator can be adjusted to the pressure level demanded by the next muscle, providing an independent force control of the muscles. The multiplexed force control concept is studied by simulations and verified with actual measurements.
Independent Identification of Friction Characteristics for Parallel Manipulators
Houssem Abdellatif and Martin Grotjahn and Bodo Heimann,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 294-302,
Mai 2007
view abstract
The compensation for friction or joint losses in robotic manipulators contributes to an important improvement of the control quality. Besides appropriate friction modeling, experimental identification of the model parameters is fundamental toward better control performance. Conventionally steady-state friction characteristics are investigated for mechanical systems in the first step. However, and due to the high kinematic coupling, such procedure is already complicated for complex multiple closed-loop mechanisms, like parallel manipulators. Actuation friction of such mechanisms becomes configuration dependent. This paper presents a methodology that deals with such challenge. The kinematic coupling is regarded in the friction model and therefore in the design of the experimental identification. With the proposed strategy, it is possible to identify the steady-state friction parameters independently from any knowledge about inertial or rigid-body dynamics. Friction models for sensorless passive joints can also be provided. Besides, the method is kept very practical, since there is no need for any additional hardware devices or interfaces than a standard industrial control. The suitability for the industrial field is proven by experimental application to PaLiDA that is a six degrees of freedom parallel manipulator equipped with linear directly driven actuators.
Individual metering fluid power systems: chahhenges and opportunities
B. Eriksson and J.-O. Palmberg,
In Proc. of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2011,
volume 225,
pp. 196-211,
März 2011
view abstract
A review of recent and current research on individual metering fluid power systems is presented. An overview of different systems and their pros and cons is given. General challenges related to independent metering fluid power systems are discussed. The major choices in the design of these systems are the hardware layout and the control strategy. The evolution of existing independent metering fluid power systems from the 1970s until the present day is also presented.
Industrial Compressed Air Usage – Two Case Studies
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
P. Eret and C. Harris and T. de Lasa and C. Meskell and G. O'Donnell,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 355-366,
März 2010
view abstract
Analyses of two industrial compressed air systems which are already installed and operating in manufacturing plants have been surveyed in the context of energy usage. The installations are quite different in compressed air needs: one is focused on actuation; while the other uses compressed air primarily for material handling. In both sites, the energy of the compressed air is evaluated at each key element of the system and the typical end use application profile is assessed. In this way, the energy balance of the system has been analyzed quantitatively, with the effect of distribution leaks accounted for directly. Combining the measured profile of the plants as currently used, scenarios for reduced compressed air usage are identified. Finally, similarities and contrasts between the two sites are drawn, and show that the basic challenges facing the process designer and plant manager in attempting to reduce the compressed air costs, and hence the cost of production, are similar across the manufacturing sector as a whole.
Industrial Digital Control in Undergraduate Fluid Power Courses: a Student-Centred Approach Using an Active Suspension Test Rig
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
J. Watton and K. Holford,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 535-542,
November 2003
view abstract
The evolution of software techniques applicable to fluid power systems has now resulted in
almost commonplace industrial application solutions that were not possible 5-10 years ago.
This is causing some discussion regarding the way undergraduate fluid power courses should
develop with respect to the inclusion of these new technologies. This paper shows how two
new activities, real-time control of an active suspension and performance monitoring, have
been developed by students for students and the way they will be brought into the
undergraduate degree scheme.
Inertial Force Display Using Pneumatics for Whole Body Haptic Interface
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Tanaka and T. Togawa and M. Okada,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 340-344,
April 2005
view abstract
Our goal is to develop environments that provide sensory input of sufficient fidelity which not only users intuitively feel they are inside a virtual world, but also are able to navigate and perform tasks with comparable skill that they display in the real world. In this paper design specifications for a new locomotion interface for rise-and-fall motion with inertial force displays are demonstrated. The locomotion interface has a seesaw mechanism for displaying vertical inertial forces and a pedaling device for supporting User mobility activities. The vertical axis of the mechanical seesaw is actuated by a pneumatic servo cylinder and can rise up and down on the user. The seesaw attached to the user can create vertically positive and negative forces that rise up and down the user creating an illusion of acceleration forces. The presence of the active seesaw mechanism allows several aspects of the locomotion to be rendered inertial forces. The head-mounted display also creates realistic environments for the rise-and fall motion. The verification of the developed system performance and design parameters such as a scale factor of the acceleration force and the phase relation between the body motion and displayed force are experimentally investigated. It is experimentally verified that the user can feel waking up the stairs through the physical immersive whole body haptic interface with the inertial
force display.
Influence of Air Temperature Change on Equilibrium Velocity of Pneumatic Cylinders
Toshiharu Kagawa and Luis R. Tokashiki and Toshinori Fujita,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 336-341,
Juni 2002
view abstract
This paper shows that equilibrium velocity of pneumatic cylinders not only depends on the effective area of the outlet speed control valve but also on the air temperature at the discharge chamber. Different equilibrium velocities were obtained experimentally with the same speed control valves, when load mass or initial pressure at the discharge chamber was changed. The different equilibrium velocities are explained by the air temperature change. Experiments are simulated using a cylinder model considering heat transfer. Experimental and simulation results are in good agreement.
Influence of assembly process on efficiency of a charge pump of axial piston machine
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
K. Klein,
2006,
pp. 131-141,
Mai 2006
view abstract
The paper deals with a numerical simulation of assembly process of a charge pump
cover of an axial piston machine. The main impulse to have this type of analysis was better
understanding of assembly process and his impact on an efficiency of the charge pump.
Logically, one can expect that assembly process, design of the charge pump cover, clamping
forces, position of bolts can influence a height of an axial sealing gap and efficiency of the
charge pump, but no quantitative evaluation of parameters was available until these analyses
have been performed. The outputs from the simulations have offered to design engineers very
detailed picture about behaviour of the cover during assembly process when cover-endcap
bolts are tightened.
This analysis also provides few ideas how height of the axial gap between the cover and the
charge pump can be reduced and efficiency of the charge pump increased. Some of them were
successfully tested and implemented in serial production.
Influence of Compressibility of Fluid on Force of Vane in High Pressure Intra-Vane Type Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Li and Y. Na and Z. Wang and C. Na,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 37-40,
April 2005
view abstract
Previously, compressibility of fluid is ignored when calculating dynamic characteristics of vane pump. When vane pump working in very high pressure, fluid's compressibility shouldn't be ignored. In the case of considering compressibility of fluid, the model of contact reaction-force in normal line direction between vane and stator is built in high pressure
intra-vane type pump, and the variation curve of contact reaction-force is obtained by Computer simulation which is closer to actual condition than former articles. When a vane moves from long radius to outlet area, variation curve of contact counterforce has a variant sharp angle, which more actual reflects the variation of contact reaction-force between vane and stator. At last, the curve of variant sharp angle is analyzed and solution is provided for the best dynamic characteristics in intra-vane type pump.
Influence of Hydro-Grinding at the Piloting Stage of a Common Rail Injector
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
A. Ficarella and A. Giuffrida and R. Lanzafame,
2008,
pp. 206-213,
September 2008
view abstract
Diesel engines equipped with direct fuel injection systems are widely used thanks to their high efficiency and their adoption in passenger cars has been increasing recently. The necessity of keeping the pollutant emissions of diesel passenger cars within the stringent limits imposed by regulations, coupled with the higher request for performance, has pushed research to new technology solutions. Common rail (CR) fuel injection equipments seem to be very effective in meeting this target, thanks to their flexibility in injection management.
This paper deals with both numerical and experimental investigations carried out with CR injectors equipped with the same nozzle but with different control valves. The control valves of the investigated injectors differ in terms of discharge properties through one of the key-hole at the piloting stage. Actually, this hole was just hydro-ground in order to achieve real increases in its discharge properties. Such an expedient was adopted to tentatively realize a modulation of the fuel injection rate.
Both simulations and experiments showed that properly modulating injection rate is difficult, but achieving a definite reduction in the quantity of fuel injected during the first stage of injection is really possible.
Influence of Pressure Control on the Power Output of a Wave Power Plant
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
J. Rösner and P. Pelz,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 383-394,
März 2010
view abstract
Alternative ways of power generation are currently under increased investigation. This paper presents a test-rig and accompanying simulation models to examine in a fundamental context certain phenomena as they occur in wave power plants and other applications of energy harvesting for oscillating structures. Different types of damping, ranging from coulomb over viscous to higher order exponents, are simulated and partly implemented in models of hydrostatic circuits to arrive at recommendations of suitable power take-off control methods. The used control methods include simple linear pressure controller as well as phase control by latching. It was found that, for ideal systems, the harvestable power is mostly independent from the damping exponent but that actual hydraulic circuits used for the power-take-off can show slightly different results.
Influence of the Experimental Procedure on the Resulting Mass Flow Rate Characteristic of a Single Pneumatic Component
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
R. d. Giorgi and S. Sesmat and E. Bideaux,
2007,
volume 3,
pp. 85-101,
Mai 2007
view abstract
The presented work investigates the existing approaches applied for characterizing the mass flow rate within a pneumatic component and tries to discuss the adequacy of the
measurement procedures and of the models for accurate simulation purposes. First is given a summary of the theoretical and empirical formulations of the mass flow rate in
an orifice in order to analyze the relevancy of the orifice model according to the measurement and the simulated circuits. Second, due to technological constraints, the circuit to be implemented for the charge or discharge methods is constituted by the cascade of several orifices. Some care is then required to determine properly the characteristic of the tested orifice or component.
Influences of supply pressure and servo valve size on accuracy of position servos
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
T. Virvalo,
2008,
pp. 15-22,
September 2008
view abstract
The servo valve is a key component in hydraulic servo systems. Traditional servo valves have high dynamics but relatively bad steady state characteristics (hysteresis, threshold). Modern servo valves have electrical spool feedback which guarantees good steady state and dynamic characteristics. It has been common practice to use quite high pressure drop in servo valves in order to guarantee good controllability. This means then high power losses in servo valves. Nowadays the energy efficiency is more and more important in different applications. In order to be competitive the energy efficient has to be taken care of hydraulic servo systems, too. In this paper the influence of the size of the servo valve and the level of supply pressure is studied on the performance and energy efficiency of the position servo system.
Influencing parameters on tightness of hydraulic seat valves
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
M. Schmidt and H. Murrenhoff and H. Lohrberg and F.-J. Körber,
2008,
pp. 467-479,
September 2008
view abstract
Seat valves provide - compared to spool valves - the advantage of being able to isolate a hydraulic pressure nearly without leakage. However, in certain applications any leakage whatsoever is prohibited. Therefore, efforts are carried out to increase the tightness of the metallic sealing.
For this purpose, a test rig was designed and built to investigate different seat geometries in combination with varying hydraulic and mechanical parameters. To exclude the influence on the leakage of other seals, the flow is measured at the low pressure side of the seat. A revision after the first set of measurements could clearly improve the test rig’s performance. By means of a structured approach, the influences of factors on leakage as well as their interdependencies are being investigated. Within this paper measurement results of the leakage’s dependency on time, contact force and geometry are presented.
Innovation of Electro-Hydraulic Systems of Forming Machines (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
M. Ožana and M. Ševčík and R. Kolek,
2008,
pp. 82-89,
September 2008
view abstract
straightening press pressing cylinder and at the same time meeting the legislation requirements according to ČSN 21 0732 („Safety requirements on design “) led the collaborating firms OCHI Inženýring spol. s r.o. and PRESSHYDRAULIKA s.r.o. to analyze, propose a new solution and realize the modern electro-hydraulic system of the straightening press PYXWM 400t of the manufacturer WMW DESAU Erfurt.
The original hydraulics of the straightening press ( the supplier ORSTA Hydraulik) has been solved by means of the standard components conforming the time, when the press was delivered (1975). Performance regulation for the pressing actuator (mode of feed rate – pressing) was assured with three-tandem hydrogenerator with a system of pressure valves that have been set by the manufacturer constantly and any adjustment required a considerable force. Such set-up of the hammer pressing force was performed by hand, by set-up of spring prestress of pressure valves.
It resulted in pressure impacts in the system at decompression after pressing and in overheating of the working medium under the influence of inadequate energy misuse and not effective thermal stabilization.
In innovated hydraulic system the source of pressure and flow rate of the regulating pump A4VSO 71 DFE1 of the manufacturer B-REX works in the mode dP = const. Electronic pressure control and the pump flow rate is realized with standard card of the pump VT-5041 manufacturer. The main pressing unit consists of the system of standard valves, it means that all volume control of movements is initiated by the regulating pump.
In the framework of research and development we have tested the bechaviour of the “mass – spring” system by comparison of internal and external control of hydro generator plate tilting. In the first case, when reduced mass of the hammer at return movement caused underpressure and the plate “fell” and it was impossible to take it back to regulation by internal control. At application of external control this situation has not been already repeated.
Innovated system of the straightening press has worked in two-shift operation already for the second year without failure. To the other applications of the innovations of the forming machines systems realized together with the firms PRESSHYDRAULIKA s.r.o. and ELCOM Automation s.r.o. that supplied the electric equipment and control system, belong the modernization of the vertical press HSDP 900 for precise pressing of fireclay blocks and modernization of injection moulding machine on plastic material of FEROMATIK F110.
Also in these systems, as a source of pressure and flow rate, there are used the regulating pumps of type A4VSO DFE … with the standard regulation cards of the manufacturer B-REX. At these machines that work in most cases in continuous operation, the question of energy saving is very desirable and that is why already with the first systems they were considered to be “energy economical”.
Control of the actuators of the vertical press HSDP 900 is realized by means of standardized „PRESS MODULES“ of the supplier B-REX that composition accepts the legislation requirements according to ČSN EN 693 and other safety codes such as UVV- prescriptions related to safety in the mother country of the manufacturer – Germany.
Innovative Drive and Control Technology for Fluid Pumps
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
B. Freissler and A. Bubb,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 417-428,
März 2010
view abstract
Due to the pulsating energy demand the energy efficiency of diaphragm dosing pumps working according to the oscillating displacement principle is not optimal. Since energy efficiency is a significant trend nowadays, we would like to present an innovative drive system for these pump types. This concerns the drive technology insofar as the drive system is supplied with a differing amount of energy depending on the kind of stroke (intake / dosing stroke) the pump is in. The hydraulic liquid end is revised in regards to the important aspects of “safety for the process, safety for the user and safety for the environment. This is done by a multi-layer diaphragm with liquid buffers and vacuum between the layers. We show functional possibilities as well as constructive basics for the usage of pump systems and accumulators. The amount of these novelties results in a higher lifetime for the diaphragm, a signalization of the diaphragm defect to the process control system and not least in a considerable efficiency increase for the whole plant.
Innovative Servo-Cartridges for presses and diecasting machines
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
V. Treffler,
2006,
pp. 60-69,
Mai 2006
view abstract
Due to the technical advantages of 2/2-way Cartridges they have been applied in various
industrial application for presses, diecasting- and injection moulding machines. In order to
reduce the cycle time of Cartridge control systems, Servo-Cartridges have been introduced to
the market. For high flow applications and closed loop control 2/2-way Servo-Cartridges
have
been developed based on a modular design concept. Servo-Cartridges from size NB40-160
with flowrates from 1000 L/min up to 40000 L/min are available. The use of different pilot
valves meets the dynamic requirements of the specific application. Depending on the
application different cone types with nonlinear flow characteristics are available. The paper
shows, for several industrial applications, the strength of Servo-Cartridges to control high
power in closed loop systems.
Innovative solution for the design, simulation, and documentation of fluid power and automated systems
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
C. Firanescu,
2006,
pp. 292-294,
Mai 2006
view abstract
No Abstract available
Instability Due to Interacting Hydraulic and Mechanical Dynamics in Backhoes
Donald Margolis and Taehyun Shim,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 497-504,
September 2003
view abstract
A backhoe is a tractor-like vehicle that has a hydraulically actuated bucket loader at the front and a hydraulically actuated backhoe shovel at the rear. The operator sits inside a canopy or cab that is mounted to the tractor chassis, and operates the hydraulic controls. The cab is typically isolated somewhat from the chassis using cab mounts. There are instances when the bucket is raised or lowered or wrapped that an instability of the entire machine is excited. In this mode, a frequency oscillation of the vehicle occurs and the operator is unable to keep his hands on the controls. This instability is investigated here and demonstrated through simulation. The instability described here is due to an interaction between the mechanical dynamics and hydraulic dynamics of the machine. All instabilities require an energy source, and, in this case, the energy comes from the fuel. It turns out that the hydro-mechanical interaction has positive feedback components and produces an instability. In order to expose the fundamental cause of the instability, a model is needed that allows the interaction of mechanical and hydraulic components. Bond graphs are a logical choice for development of the model. Bond graphs are a concise pictorial representation of the interactive dynamics of all types of energetic systems. They allow the model to be developed in pieces and then put together into an overall computational model. This procedure is demonstrated for the system here. The end result is a reasonably low order model that exposes the fundamental cause of the instability in backhoes. It also allows assessment of cures for the problem, some requiring redesign of components, and some requiring an automatic stabilization control system.
Instantaneous Flow Rate Measurement of Ideal Gases
K. Kawashima and T. Kagawa and T. Fujita,
In ASME Journal of Dynamic Systems Measurement Control,
2000,
volume 122,
pp. 174-178,
März 2000
view abstract
In this paper, a chamber called an "Isothermal Chamber" was developed. The isothermal chamber can almost realize isothermal condition due to larger heat transfer area and heat transfer coefficient by stuffing steel wool in it. Using this chamber, a simple method to measure flow rates of ideal gases was developed. As the process during charge or discharge is almost isothermal, instantaneous flow rates charged into or discharged from the chamber can be obtained measuring only pressure in the chamber. The steady and the unsteady flow rate of air were measured by the proposed method, and the effectiveness of the method was demonstrated.
Instantaneous Liquid Flow Rate Measurement Using the Dynamic Characterisitics of Laminar Flow in Circular Pipes
Proceedings of 4th ASME/JSME Joint Fluids Engineering Conference (FEDSM 2003)
B. Manhartsgruber,
2003,
Instantaneous Liquid Flow Rate Measurement Utilizing the Dynamics of Laminar Pipe Flow
B. Manhartsgruber,
In Transactions of the ASME, Journal of Fluids Engineering,
2008,
volume 130,
pp. 121402-1 - 121402-8,
Dezember 2008
view abstract
This paper deals with the utilization of the dynamic characteristics of laminar flow in circular pipes for the indirect measurement of flow rates. A discrete time state space realization of the transmission line dynamics is computed via inverse Laplace transform and an identification and model reduction method based on the singular value decomposition. This dynamic system is used for the computation of the flow rate at one end of a pipe section. Special attention is paid to the identification of the speed of sound and the dimensionless dissipation number of the pipe section, since exact knowledge of these parameters is crucial for the reliability of the measurement results. First experimental validation results are given in a limited range of operating frequencies between 100 and 2000 Hz. Flow-rate variations within +/-1.2 l/min have been measured with an uncertainty of +/- 0.07 l/min at the 95 % confidence level. The test fluid was mineral oil.
Intake Air Path Diagnostics for Internal Combustion Engines
Matthew A. Franchek and Patrick J. Buehler and Imad Makki,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 32-40 ,
Januar 2007
view abstract
Presented is the detection, isolation, and estimation of faults that occur in the intake air path of internal combustion engines during steady state operation. The proposed diagnostic approach is based on a static air path model, which is adapted online such that the model output matches the measured output during steady state conditions. The resulting changes in the model coefficients create a vector whose magnitude and direction are used for fault detection and isolation. Fault estimation is realized by analyzing the residual between the actual sensor measurement and the output of the original (i.e., healthy) model. To identify the structure of the steady state air path model a process called system probing is developed. The proposed diagnostics algorithm is experimentally validated on the intake air path of a Ford 4.6 L V-8 engine. The specific faults to be identified include two of the most problematic faults that degrade the performance of transient fueling controllers: bias in the mass air flow sensor and a leak in the intake manifold. The selected model inputs include throttle position and engine speed, and the output is the mass air flow sensor measurement.
Integrated Electric-Hydraulic Drives for Power and Motion Control
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
D. Wehner and S. Helduser,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 81-84,
April 2005
view abstract
Common hydraulic power units consist of a standard hydrostatic pump driven by an electric motor. In some applications they do not represent the best solution. Electric motors often require much space in comparison to the hydrostatic pump. The fan of the motor produces noise and lowers the efficiency. The coaxial arrangement of motor and pump requires sensitive shaft seals.
The integration of hydrostatic pumps and electric motors offers some interesting possibilities to get profitable solutions. Existing designs were done for special applications what makes them expensive and less flexible. But they can show the benefits of integrated designs.
Considering the variety of electric motors and hydrostatic pumps, combinations can be expected. Not each combination will deliver a promising solution. This requires a systematic approach.
A first prototype was designed as a combination of an Axial-Piston-Pump and a Servomotor. The aim was to get a simple design by using as much standard parts as possible. The main design features will be discussed and shown. The description of some design particularities shows achievable advantages.
The realised prototype keeps the same width and reduces the length by 23 %. No moving parts need to come out, so sensitive shaft seals can be left out. The integrated oil cooling increases the power density. But the prototype offers a lot of possibilities to get experimental results. Efficiency measurements can be done as well as the validation of cooling effects and other special design features.
Integrated Safety in Closed-Loop Controlled Electro-Hydraulic Drives
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
S. Richter and S. Helduser,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 125-137,
März 2010
view abstract
This paper describes the systematic development process of new safety concepts based on EN ISO 13849 for closed-loop controlled electro-hydraulic drives. Due to the heavy dependence of the safety requirements on the application, the results are illustrated with a concrete example of a machine. The objective is to integrate safety functions directly into the drive in form of hardware and software. This will minimize additional costs caused by safety requirements. The attractiveness of electro-hydraulic drives will increase if the machine manufacturer can use a complete safety solution. This will significantly reduce the effort of developing protective measures.
Integrated System ID and Control Design for an IC Engine Variable Valve Timing System
Zhen Ren and Guoming G. Zhu,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
März 2011
view abstract
This paper applies integrated system modeling and control design process to a continuously variable valve timing (VVT) actuator system that has different control input and cam position feedback sample rates. Due to high cam shaft torque disturbance and high actuator open-loop gain, it is also difficult to maintain the cam phase at the desired constant level with an open-loop controller for system identification. As a result, multirate closed-loop system identification becomes necessary. For this study, a multirate closed-loop system identification method, pseudo-random binary signal q-Markov Cover, was used for obtaining linearized system models of the nonlinear physical system at different engine operational conditions; and output covariance constraint (OCC) controller, an H2 controller, was designed based upon the identified nominal model and evaluated on the VVT test bench. Performance of the designed OCC controller was compared with that of the well-tuned baseline proportional-integral (PI) controller on the test bench. Results show that the OCC controller uses less control effort and has significant lower overshoot than those of PI ones.
Intelligent Control for Artificial Damping in Hydraulic Crane Systems under Load Dynamics
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Yong and K.-E. Rydberg,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 119-123,
April 2005
view abstract
In this Paper, an intelligent fuzzy-PI compound control which is composed of a fuzzy control, a feedforward proportional control and an intelligent integral control, is proposed to adjust the damping in a hydraulic crane system under load dynamics. Position and pressure signals in the hydraulic system are fed back to control the damping of the crane tip. That the right artificial damping without high losses in dynamical performance will be realized by adding the compound control into the crane system. Simulation results show that this intelligent fuzzy-PI feedback control can effectively coordinate the damping and dynamical characteristic in the hydraulic damping system. Also the adaptation of the system to different load conditions can be made stronger.
Intelligent Microprocessor-based Multiple Channels Temperature Controller
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
D. Ning and B. Jin and Y. Zhou and Z. Weng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 777-780,
April 2005
view abstract
Temperature is a very important parameter in the manufacturing production of plastic and rubber. In this paper, a new type of intelligent temperature controller is discussed. As a whole, our attentions are paid to the accuracy of the temperature detection, the quick response of the variety of temperature and the stabilization of the temperature control. The temperature controller has seven independent channels and seven amplifying circuits. So seven points' temperature can be detected exactly and controlled independently. The controller also has a RS-485 communication port to communicate with the up controller on line. The PID algorithm is utilized to efficiently control the temperature. The PID results are used to control the relays with PWM signal, so that high control accuracy can be achieved.
This controller has been applied in the control of the plastic jetting-molding machine. Experimental results have shown that it has good function in the temperature control of plastic and rubber machines.
Intelligent Oil Flow Management with EFM: The Potentials of Electrohydraulic Flow Matching in Tractor Hydraulics
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
K. Mettälä and M. Djurovic and G. Keuper and P. Stachnik,
2007,
volume 3,
pp. 25-33,
Mai 2007
view abstract
Electrohydraulic flow matching (EFM) is a new concept for the implement hydraulics in mobile working machines. From a large variety of alternatives, some solutions were selected for practical testing in a tractor. The system is based on commercially available components from the mobile hydraulics components program of Rexroth. The first test results confirm the suitability of the concept in practice. It shows especially good dynamic behavior as well as low energy consumption. The commands from the operator are transferred directly and without delay into working movements in the machine.
Therefore, the operator is less stressed and the operation of the machine becomes easier.
Intelligent switching control of a pneumatic muscle robot arm using learning vector quantization neural network
K. K. Ahn and H. T. C. Nguyen,
In Mechatronics,
2007,
volume 17,
pp. 255-262,
view abstract
Pneumatic cylinders are one of the low-cost actuation sources used in industrial and prosthetic application, since they have a high power/weight ratio, high-tension force and long durability. However, problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. To overcome these shortcomings, a number of newer pneumatic actuators have been developed, such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle (PAM) Maniplulators. In this paper, the solution for position control of a robot arm with slow motion driven by two pneumatic artificial muscles is presented. However, some limitations still exist, such as a deterioration of the performance of transient response due to the changes in the external load. To overcome this problem, a switching algorithm of the control parameter using a learning vector quantization neural network (LVQNN) is proposed in this paper. The LVQNN estimates the external load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external working loads.
Interaction Between Secondaries in a Thermal-Hydraulic Network
Weihua Cai and Walfre Franco and Gregor Arimany and Mihir Sen and K. T. Yang and R. L. McClain,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 820-828,
Dezember 2006
view abstract
The design of one secondary loop of a complex network often neglects the effect that its operation has on the others. The present is a study of hydrodynamic and thermal interaction between secondaries in a thermal-hydraulic network as the system goes from one steady state to another. Experimental results are related to those derived from a mathematical model. The network consists of a primary and three secondary loops. There is a water-to-water heat exchanger on each secondary, with the cooling coming from the primary and the heating from a separate loop. A step change is introduced by manually actuating a valve in one of the secondaries, resulting in changes in the other loops also. The response time of the temperature is found to be an order of magnitude higher than that of the flow rate, which is again an order of magnitude higher than the pressure difference. The steady-state results show that there is significant interaction, and that it is dependent on the initial operating condition. The hydrodynamic and thermal responses are found to be very different.
Internet-based Bilateral Force-feedback Telecontrol of Hydraulic Master-Slave Robot
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Xiu and P. Wu and A. Kitagawa and S. Jing,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 704-708,
April 2005
view abstract
Time-delay and its characteristic of uncertainty will cause the telecontrol system to be unstable. In this paper, the different time-delay characteristic under TCP and UDP is discussed, and the arising problems of the two protocols when used in telecontrol system are presented. Then Sampled-information Observer for UDP is brought out. And after the discussion of the master-slave operation, this paper proposed one kind of control architecture based on compensator, which can ensure the stability of the telecontrol system. Furthermore sliding mode structure is developed in order to make the compensation more effective.
Internet-based Collaborative Design for Hydraulic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Rong and P. Li and K. Chen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 85-88,
April 2005
view abstract
Hydraulic system design is a complex process whereby geographically distributed designers from different disciplines cooperate and collaborate. This Paper presents a multi-tier multi-agent collaborative design framework for hydraulic system, which integrates hydraulic component design, hydraulic circuit design, hydraulic circuit simulation and production planning and design. Enabling technology such as multi-agent and XML web service are used to develop this framework. The proposed framework is applicable to different requirements of design participants and enhances design interaction.
In-the-Loop Method for Control Strategy Development and Virtual Commissioning
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
O. Breuer and R. Kett,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 593-603,
März 2010
view abstract
To fulfill the requirements of contemporary development of electro-hydraulic systems, currently used simulation methods appear to be insufficient in many cases. The integration of all involved parts of the system like controller hardware and algorithms into the development process at an early state is increasingly getting important. The logical continuation of this judgement is to account the interconnection between process and actuator control, both either in hard- or software, and the virtual system simulation as a virtual commissioning to test software algorithms and safety functions in a safe environment. Afterwards, the gap between the simulation model and the realised system shrinks down what implicates less amount of work and more efficiency.
Inverse Simulation of an Aerospace Redundant Electro-Hydraulic Actuator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Nfonguem and J.-C. Maré,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 518-521,
April 2005
view abstract
The paper presents the power sizing and analysis of an electrohydraulic jackscrew used to fix the position of a secondary flight control surface. At the design level, it is interesting to analyze the actuator energy consumption and the control signals to be sent to the actuator valves in order to compare different power transmission architectures. This is done with resort to inverse modeling and dynamic simulation of the actuator, given the surface deflection and the aerodynamic load that it has to hold. The direct modeling of the actuator is not consistent with this objective as it requires data on the actuator control (structure and parameters) at the preliminary design stage. Oppositely, the inverse modeling used in the present study allows to calculate backwards the system energy variables, from known output (at the moving load level) to input (at the metering valves level). The presence of friction devices and dual load path in the power chain of the jack induce some simulation and modeling problems when implemented in the inverse way. Using the bi-causal Bond-graph modeling approach helps to point up the barriers and to cope with them. It is hereby proposed to define flux or effort contribution factors that add the required number of constraints that are necessary to solve the algebraic-differential inverse problem. The implementation and the adaptation of the screwjack model is performed in the Dymola/Modelica environment that is well suited for acausal simulation. The work is organized in order to generate a working base in the comparison of electro-hydraulic and electromechanical actuation with respect to energy consumption.
Investigation of Elastic Deformations of Cylinders within the Simulation of Piston-Cylinder- Contacts of Axial Piston Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
S. Gels and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 75-88,
März 2010
view abstract
Axial piston pumps are used in several industrial applications. The geometry of the probably most important tribological interface of these pumps, the piston-cylinder-interface, is mostly optimized by comparing test bench results. Only a few simulation tools have been used to optimize the geometry such as gap width, cylinder length, etc.
In the past months, a simulation tool has been built up at IFAS, to simulate the piston cylinder contact of axial piston machines. The simulation program is basically a numerical solver of the Reynolds equation. It also considers several other physical effects, such as the mechanical behavior of the beam, mixed friction etc.
Simulations show that the modeling of elasticity and deformation of the cylinder due to local pressure peaks has high influence on the simulation results. The paper focuses on different models for modeling the elasticity of the cylinder and compares simulations to test-bench results.
Investigation of Experimental Techniques for the Measurement of the Effective Bulk Modulus of Oil-Filled Pipes and Hoses
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
H. Gholizadeh and D. Bitner and R. Burton and D. Sumner,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 179-192,
März 2010
view abstract
The fluid bulk modulus can be defined mathematically as the slope of a strain-strain curve within the range of linearity. Interaction of fluid compressibility and mechanical mass plays a significant role in hydraulic systems performance. Therefore, it is very important to know the correct bulk modulus of the hydraulic systems. The bulk modulus of the fluid can be obtained by the manufacturer, but there are two other more important factors that also affect the bulk modulus: entrained air and mechanical compliance (associated
with pipes, hoses and other components). For this reason, an “effective” bulk modulus has to be used for fluid power system analysis. The effect of pipe elasticity on bulk modulus is important particularly if a flexible hose is used. The effect of flexible hose elasticity can in some instances be significant in terms of the response of hydraulic systems when compared to using steel piping. However, information about the compressibility of hoses is often not provided by the manufacturers. This lack of information makes it difficult to model hydraulic systems and as such it is necessary to establish techniques to measure this information experimentally. The aim of this research is to design and fabricate a test rig to determine volumetric expansion of hydraulic hoses under hydrostatic pressure and to establish an experimental protocol to obtain reliable and repeatable measurements of the hose compressibility. Important measuring parameters are the fluid pressure and the change in volume of the hose under controlled temperature conditions. An important
conclusion in this study is that the way an experiment is conducted can readily affect the measured value of the effective bulk modulus and great care must be taken to ensure that the experimental protocol is valid and reliable.
INVESTIGATION OF FLOW STRUCTURE INSIDE SPOOL VALVE WITH FEM AND PIV METHODS
D. Gao,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 51-66,
März 2004
view abstract
In this paper, the finite element method (FEM) and particle image velocimetry (PIV) techniques are utilized to
obtained the flow field along the inlet passage, chamber, metering port, and outlet passage of a spool valve at several
different geometrical dimensions. For numerical simulation, the stream function ψ and vorticity ω forms of continuity
and Navier-Stokes equations are employed, and the finite element method is applied to discretize the equations. Selfdeveloped simulation codes are executed to compute the values of the stream function and vorticity at each node in the
flow domain. Then, according to the correlation between the stream function and velocity components, the velocity
vectors of the entire field are calculated. For particle image velocimetry experiments, a pulse Nd: YAG laser is
exploited to generate a laser beam. Convex and concave lenses are combined with each other to produce a 1.5-2 mm
thickness laser sheet to illuminate the desired plane. Polystyrene spherical particles with a diameter of 30-50 μm are
seeded into the fluid as tracing particles. A Kodak ES1.0 CCD camera is employed to capture the images of interest.
The images are processed by FFT cross-correlation algorithm, and the processing results are displayed in the form of
velocity vector plots. Numerical simulation results and PIV experiments both show that there are three main areas in the
spool valve where vortices are formed. Numerical results also indicate that the valve opening and the chamber
dimensions have some effects on the flow structure of the valve. The investigation is helpful for qualitatively analyzing
the energy loss, noise generation, and steady state flow forces. It can even help in designing the geometrical structure
and flow passage.
INVESTIGATION OF LOW TEMPERATURE BEHAVIOR OF ENVIRONMENTALLY COMPATIBLE HYDRAULIC FLUIDS DUE TO AGEING
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
O.-C. Göhler and H. Murrenhoff,
2006,
volume 1,
pp. 143-149,
Juni 2006
view abstract
Beside other properties, the behavior at low temperatures determines the fields of application. Especially for mobile
applications an adequate fluidity at low temperatures is necessary. In the presented investigation the pourpoint is
measured at regular intervals throughout an ageing test. The used test-rig imposes typical loads of hydraulic circuits,
such as pressure and temperature level, on the fluid and has been used to analyze the ageing properties of fluids.
During an ageing test fluid samples are taken and analyzed to determine the degree of ageing. This is accompanied by
the measurement of the pourpoint to describe the influence of ageing on low temperature behavior. As a reference the
basestock of a commercial synthetic ester is tested. The comparison with the behavior of the newly developed fluid will
show the effect of the chemical modifications.
INVESTIGATION OF NOISE SOURCE REDUCTION STRATEGIES IN HYDROSTATIC TRANSMISSIONS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
R. Klop and M. Ivantysynova,
2008,
pp. 63-76,
Juli 2008
view abstract
The objective of this work is to outline a method to integrate current knowledge of noise source generation in
hydrostatic pumps and motors with transmission line modelling techniques to accurately predict superimposed pressure
and flow pulsations in hydrostatic transmissions. The proposed method uncovers potential for both pump/motor and
system design techniques to significantly reduce noise source generation in hydrostatic transmissions. Simulations
were conducted to illustrate the ability to predict superimposed flow pulsations throughout the connecting lines as well as oscillating forces and moments dependant on system pressure variances. Validation of an integrated
pump/motor/connecting line model is planned by taking both hydraulic and acoustic measurements to relate
transmission noise sources with audible noise source levels. The developed transmission model is shown as a vital
design tool in developing more compact and quiet hydrostatic transmissions.
Investigation of Oil Contamination Monitoring System Based on Especial Filter Membrane
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Jingyi and Z. Qisheng and L. Kan and T. Hao ,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 637-641,
April 2005
view abstract
The relative oil contamination control theory and before it and on-line monitoring method being deeply investigated and analyzed, the filter membrane being sensor, fill-up method being theory compared with Virtual Instrument application, a suit of oil contamination on-line monitoring system was developed.
INVESTIGATION OF POWER LOSSES IN THE LUBRICATING GAP BETWEEN THE CYLINDER BLOCK AND VALVE PLATE OF AXIAL PISTON MACHINES
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
J. Baker and M. Ivantysynova,
2008,
pp. 302-319,
Juli 2008
view abstract
The lubricating gaps are the primary source of energy dissipation in piston machines. The paper presents results of a
simulation study that investigates the effect that micro surface shape variations on the cylinder block gap surface have on
power loss in the cylinder block valve plate interface. As the gap height of the lubricating film represents the most critical
parameter relating to pump performance, special attention is given to the relation between gap height, operating
parameters, surface design and power loss. A special in house code has been used for this research study. The simulation
model covers fluid structure interaction and micro motion of the cylinder block resulting from oscillating piston forces.
Details of the model are explained. The model allows for analysis of the pressure and velocity fields generated in the
lubricating film and calculates leakage, viscous friction and energy dissipation. Finally, simulation results obtained from a
complete pump model considering all three gaps of a swash plate axial piston pump are compared with measurement data.
Investigation of Separate Meter-In Separate Meter-Out Control Strategies for Systems with Over Centre Valves
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
H. C. Pedersen and T. O. Andersen and R. H. Hansen and S. Stubkier,
2010,
pp. 145-158,
September 2010
view abstract
Traditionally most mobile hydraulic systems are fitted with over centre valves for safety measures. However, it is a well known that over centre valves in combination with flow control valves may lead to oscillatory and unstable system behaviour if not designed correctly. There are several means to overcome this problem, but it typically implies higher energy consumption and/or decreased control performance. With the development of robust sensors and new valve types with separate meter-in, separate meter-out control it is, however, possible to overcome these stability problems in a much more intelligent way, also adding increased functionality to the system. The focus of the current paper is therefore on investigation of different control strategies for Separate Meter-In Separate Meter-Out (SMISMO) control of general
single axis hydraulic system with a differential cylinder and an over-centre valve included.
The paper first presents a general model of the system considered, which is experimentally verified. This is followed by a discussion of different control strategies and their implications. For each of the control strategies controllers are described, taking into account the dynamics
of the system and the coupling between the two cylinder chambers. Based on the described controllers the different control strategies are evaluated through via simulations and experimentally on a scale model of an excavator arm. Based on the findings, the performance of the different controllers are discussed and possibilities and limitations of the controllers are described.
Investigation of the Acceleration Effect on Dynamic Friction of EHA System
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Li, Wei and Burton, Richard and Habibi, Saeid and Schoenau, Greg and Wu, FangXiang,
2010,
pp. 367-381,
September 2010
view abstract
In some early modeling studies on a high precision Electro-Hydrostatic Actuator (EHA) by the authors, it was observed that under certain conditions, limit cycles were predicted
in the output actuator displacement but were not observed physically even though the parameters used in the modeling were based on experimental measurements. It was
suspected that the measured (and subsequently modeled) friction characteristics of the actuator were part of the reason for this discrepancy.
In this paper, dynamic friction modeling of the EHA is experimentally investigated. It was found that the traditional steady-state friction characteristic – the so-called Stribeck effect obtained by measuring the friction forces at different constant velocities - is a poor representation of the true dynamic friction when the EHA experiences various accelerations during the control process, such as the step response.
In this paper, a new term “unsteady state friction” is defined and subsequently measured, examined, and analyzed. Experimental results reveal that this unsteady state
friction is a more general form of the dynamic friction. In addition steady state friction is just a special case of the unsteady state friction, which is highly acceleration
dependent. When the acceleration increases, the Stribeck effect decreases, indeed, can reach conditions where it no longer exists within the operating velocity range. A novel
experiment to measure the friction of the EHA system is presented. A new nonlinear friction model (a 3D surface model) including the acceleration factor is proposed, which
indicates that the Stribeck curve is just a special case of the dynamic friction model when the system acceleration is approaching zero. This result can be applied to any
actuator (linear and rotary) and provides a new way in which the dynamic friction can be viewed and modeled.
Investigation of the Effects of Swashplate Angle and Suction Timing on the Noise Generation Potential of an Axial Piston Pump
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
V. Wicke and K. A. Edge and N. D. Vaughan,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 77-82,
November 1998
view abstract
The paper presents theoretical work carried out with the simulation program Bathfp. Models simulating the dynamic behaviour of axial piston pumps have been extended to investigate piston forces for different valve plate timings and for different swashplate angles. These forces have then been used to calculate the mean and fluctuating components of the moment functions. Since the forces and moments together are the most important inputs causing structure borne noise, the influence of the swashplate angle on the structure borne noise could be investigated. The influence of the suction port timing on both structure borne and fluid borne noise potential is also discussed.
Investigation of the Structure-Borne Noise Transmission Behaviour of Hydraulic Hoses
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
U. Heisel and V. Slavov,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 243-252,
März 2010
view abstract
Regarding the efforts to reduce the sound emission and impact of hydraulic systems it be-comes more and more important to gain knowledge about the structure-borne noise transmis-sion behaviour of such systems. This paper presents an investigation of the structure-borne noise transmission through high-pressure hydraulic hoses. The influence of the constructive and operating parameters on the transmission behaviour of the hoses was shown for different types of excitation. In the follow-ing, the boundary conditions for the subsequent simulation were determined. The findings and measurement results from the studies shall be used to develop hose models for the FE simulation of the structure-borne noise transmission. Moreover, they should be transferred and adapted to other hydraulic systems in order to facilitate the simulation of the dynamic structure-borne noise transmission behaviour of the complete hydraulic system.
Investigation of Various Power Management Strategies for a Class of Hydraulic Hybrid Powertrains: Theory and Experiments
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
R. Kumar and M. Ivantysynova,
2010,
volume 1,
pp. 87-99,
Juni 2010
view abstract
Various power management strategies are investigated for a class of hydraulic hybrids based on the output-coupled
power-split transmission. The hydraulic counterpart of the electric hybrid Toyota Prius is proposed as the basis of
comparison. A number of standard drive cycles are simulated under instantaneous optimization based control,
Stochastic Dynamic Programming (SDP) based control and Dynamic Programming (DP) based optimal control. Fuel
economy results are compared to assess the effectiveness of each sub-optimal control against the benchmark solution.
Measurement results collected on a powertrain test-rig for a sample drive cycle operating under the proposed power
management strategy have been compared to the ones predicted by the simulation.
Investigation of Wear on a Pressure Compensator Spool in a Mobile Proportional Valve
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. O. Andersen and M. R. Hansen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 420-424,
April 2005
view abstract
This paper investigates the wear properties of spool valve design. In particular is looked into the design of a pressure compensator spool for use in a mobile hydraulic valve in the pump side module. The paper argues that the shown design is very sensitive to production tolerances, and that the lateral forces on the spool valve are almost certain of a considerable size. Blackburn has shown that a tapered spool decentered in bore generates a lateral force as a function of the tolerances. In the paper we show that the worst case, and a more realistic one, is when we have a tilted spool. Calculation shows that this is the geometrical situation where the lateral force becomes maximum. This combined with other design characteristics such as noise phenomena, high pressure ports and low pressure ports separated by a short land, number of lands, leads to some important design criteria, and in the considered case to a new spool design.
Investigations of Electrohydraulic Servo Valves with Piezo Bender as Control Element
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
Dariusz Sedziak,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 511-522,
März 2010
view abstract
One of today promising idea is usage of piezoelements like piezo stack or piezo-benders as control elements for hydraulic and pneumatic valves. In the paper results of investigations of two electrohydraulic servo valves with piezo bender was shown. The main modifications of two types of servovalves (with barometric and electronic feedback) and simulation models were presented. Results of simulations and experimental characteristics will be shown and discussed.
INVESTIGATIONS OF THE TEMPERATURE BEHAVIOUR OF THE PISTON CYLINDER ASSEMBLY IN AXIAL PISTON PUMPS
L. Olems,
In International Journal of Fluid Power,
2000,
volume 1,
pp. 27-38,
März 2000
view abstract
In this paper the temperature behaviour of the piston cylinder assembly in swash plate type axial piston pumps is investigated.
For the theoretical investigations a mathematical model is used that allows the calculation of the nonisothermal
gap flow between piston and cylinder. For this purpose the Reynolds Equation, the energy equation and the
equations of motion have to be solved. The gap flow and the pressure distribution in the gap is calculated by solving the
Reynolds Equation numerically with a finite volume method. The temperature distribution is obtained by solving the
energy equation over the piston cylinder assembly also numerically with a finite volume method. It is known that the
piston undergoes an eccentric motion in the cylinder that has a significant influence on the gap flow. To calculate this
motion a simplified equation of motion, based on the external forces, the hydrodynamic forces and the forces caused by
elastic deformation, is used. A method is described that combines the calculation of these three equations and that allows calculation of the gap flow and the temperature distribution in the assembly depending on the design and the operating parameters of the machine. The experimental investigations were made on a standard pump that was modified for the measurements. The temperature distributions in the whole cylinder block of the machine and the dynamic pressure
in the displacement chamber were measured under real operating conditions using a telemetry unit. The results were
used to verify the simulation model.
Investigations on Internal Flow of Pneumatic Vacuum Ejectors
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
A. Leonhard and S. Helduser,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 233-246,
März 2010
view abstract
The paper shows CFD simulations of the flow in pneumatic vacuum ejectors. The typical characteristics of the internal flow and their relation to the ejector performance are discussed. The results of CFD analysis are compared with several analytical models from literature, which describe typical phenomena of the ejector flow. The activities are the basis for creation of a 1D model for calculation of ejector performance in dependency of the internal geometry.
IT AND CHINESE FLUID POWER INDUSTRY
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
B. Ye and Y. Chen and C. Yang,
2000,
pp. 363-370,
September 2000
view abstract
IT has been revolutionizing the traditional industry. In china, Fluid Power Industry is faced to a great chance
and challenge. Many Chinese enterprises in this field are small scale, how make them more smart and competitive
in international market? The one of key answer is building a good information infrastructure in whole
Industry. ChinaHPS, a web-based information network constructed by the State Key Lab of Fluid Power
Transmission and Control (SKLoFP), Zhejiang University, provides a platform of information exchanges for the
fluid power industry both at home and abroad. This paper deals with the technical realization and structure of
ChinaHPS.
Joint Air-Fuel Ratio and Torque Regulation Using Secondary Cylinder Air Flow Actuators
A. G. Stefanopoulou and J. A. Cook and J. W. Grizzle and J. S. Freudenberg,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 638-647,
Dezember 1999
view abstract
Actuation schemes exist that permit the joint management of air and fuel flow into the cylinders of a spark ignition engine. With the exception of drive by wire systems, to-date, the transient control aspects of these schemes, collectively refered to here as secondary cylinder air flow actuators, has not received any attention from the control community. This paper takes a first step in the analysis of the simultaneous dynamic control of air fuel ratio and torque response using secondary actuators placed before the intake ports of the cylinders, when used in combination with standard fuel injectors and primary throttle regulated by the driver. The emphasis is on basic issues of designing a feedforward scheme to enhance actuator authority for feedback control, and the fundamental multivariable nature of the feedback problem. Enhanced transient air-to-fuel ratio performance improvement is shown to be possible without sacrificing engine torque response with respect to a conventional engine. In addition, this is achieved with overall higher manifold pressure, offering the possibility of reduced pumping losses in the engine, depending on the actual actuation scheme employed.
JOURNAL BEARING PERFORMANCE IN GEAR PUMPS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
M. Gutés and P.J. Gámez Montero and R. Castilla and E. Codina,
2000,
pp. 259-269,
September 2000
view abstract
This paper is the current status summary of a Ph.D. work, which subject is the hydraulic external gear pumps,
with pressure compensated lateral plates. Concretely, the aim is to determinate the behaviour of the plain journal
bearing, i.e. found theoretically and experimentally, the orbits of the shaft v.s. the lateral floating plate,
where the bearing is located. The Thesis is a part of an European project, concretely a Brite-Euram project
centred on investigating the performance of an existing gear pump, focused to the industry site and, in this case,
to the Spanish manufacturer of the pump being studied, the company Roquet, S.L. For this reason the aim of the
finite element simulation is to give support to the experimental results, being these the most important part of
this Thesis. Subsequently a summary of the theoretical work done, that is finding the orbits of the shaft by FEM
integration of the 2D Reynold’s equation will be explained. As well, measurements of the shaft’s orbits, and
movements of the lateral plates on a real unit under pressure are shown. These measurements are done without
contact by laser probes.
Key Technology of Electro-hydraulic Control System for Automatic High-speed Railway Rail-laying Machinery
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Zhao and Y. Li and L. Yang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 826-830,
April 2005
view abstract
This paper introduces electrohydraulic control system composition and characteristics of the high-speed railway rail layer, shows the networked control system scheme based on controller area network (CAN) field bus, resolves some bottleneck problems of rail layer, such as laying sleeper, traction, driving and automatic guiding control, it can realize the harmony and optimization between layer running working.
Kinematic Analysis of a Swash-Plate Controlled Variable Displacement Axial-Piston Pump With a Conical Barrel Assembly
Zhiru Shi and Gordon Parker and Jonathan Granstrom,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
Januar 2010
view abstract
Variable displacement, swash-plate controlled, axial-piston pumps are widely used in applications that require high pressure and variable flow rates. The pump consists of a rotating barrel assembly that houses several pistons in a circular array. A swash-plate is used to control the displacement of the pistons to adjust the output flow of hydraulic fluid. As the barrel rotates, the pistons slide along the angled swash-plate and draw oil from the supply and then discharge oil into the high pressure circuit. This results in an almost constant output flow rate. This paper analyzes the kinematics of a pump based on its geometry dependent characteristics. The analysis assumes an idealized case in which there is no oil leakage and the fluid is considered to be incompressible. It is revealed through the analysis that the piston displacement and the pump output flow are slightly increased by using a conical barrel. Instantaneous and mean flow rate equations are used to describe the output flow characteristics and flow ripple effect. The output flow rate ripple profile is found to be a function of both swash-plate angle and the conical barrel angle. A term defined as the flow rate uniformity coefficient is used to better quantify the flow ripple phenomenon. A frequency analysis is performed on the output flow rate and an additional order is found to be present when using a conical barrel pump versus one with a cylindrical barrel when the pumps have an odd number of pistons. Conical barrel piston pumps are found to have a slight increase in piston displacement, velocity, and acceleration relative to the rotating barrel frame of reference over a pump with a cylindrical barrel. This translates into an increase in the output flow rate for a conical piston pump under the same operating conditions. The conical barrel is also found to have a reduction in the rotational inertia allowing for faster angular acceleration. The presence of an extra order from a frequency analysis for a conical pump with an odd number of pistons has the potential to cause unwanted noise or vibration to the structure or components attached to the pump.
KNOWLEDGE AND REASONING: ISSUES RAISED IN AUTOMATING THE CONCEPTUAL DESIGN OF FLUID POWER SYSTEMS
M. Darlington and S. Culley and S. Potter,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 75-85,
August 2001
view abstract
Much progress has been made in the area of computer-aided designer support, but little has been made in that of design
automation. Where progress has been made, it has been largely in the analytical aspects of the task (for example,
simulation and stress analysis) – tasks for which computers are more suited than humans. Less tractable is automation
of the early, conceptual, phase of design, heavily reliant as it is on the expert knowledge of the design practitioner.
Emulating this computationally is the domain of Artificial Intelligence (AI) and requires a detailed understanding of the
nature of the design process (Darlington et al, 1998).
This paper discusses some of the issues raised during an investigation in to the automation of the configuration
phase of fluid power system design, and identifies some of the hurdles to be cleared before automation, supported by
AI, becomes a reality. Two models, developed by the authors, are chosen to illustrate the way in which very different
approaches can be taken to automating the same task with an emphasis on the knowledge that is used by designers,
which must be acquired and used in automation.
Latest Development of Crankshaft Design Radial Piston Hydraulic Motors: High Torque High Speed Variable Displacement Motors for Hydrostatic Transmissions
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
V. Pecorari and D. Pecorari and G. Pecorari,
2007,
volume 1,
pp. 39-50,
Mai 2007
view abstract
The paper will describe the enhancements in the overall efficiency of a construction machine that can be obtained by using a dual displacement crankshaft design radial
piston hydraulic motor capable of running at very high speeds. Different products have been examined in order to cover a wide range of applications and working conditions.
Most of the results are the outcome of significant application studies, which led to the development of prototypes. The common essential feature of all the prototypes was a dual displacement system applied to a crankshaft design radial piston hydraulic motor suitable for very high speeds. Some of the prototypes are currently used by major world-wide construction industries. A typical system to be developed was a dual speed
hydraulic transmission. Most of the construction machines in fact, are being designed for having two operational modes: the slow mode, when the machine is under heavy loads and moves with a relatively low speed, and the fast mode, when the machine is
virtually unloaded and moves faster on the work ground. The variation of the motor displacement is obtained by a variation of the eccentricity of the crank of the shaft.
Hence, the motor can shift in a continuous manner from the maximum to the minimum displacement, with a smooth variation in terms of torque and speed. The wide operational range coupled with very high efficiency both in minimum and in maximum
displacement, allows the hydraulic system to adjust the engine working conditions in a smaller range closer to that of the maximum efficiency. The major consequences being
less exhaust emissions, less thermal losses, longer machine life, without forgoing the performances of the equipment, rather improving them. The objectives of the analysis
were to capture the essential benefits of the application of these hydraulic components referring in particular to the overall efficiency in order to determine the enhancements
with respect to the traditional hydraulic motors. The ultimate aim was to identify candidates for optimal application in terms of performance and design. The results obtained show that with the use of such a component, thanks to its high starting toque,
even in minimum displacement, and its very high maximum speed, the system gains elasticity, performance and overall efficiency.
Layout Program in the Sealing Technology
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
D. v. Borstel and G. Wuestenhagen,
2007,
volume 2,
pp. 239-247,
Mai 2007
view abstract
Sealing elements have become a very important part of our technical world. Nearly all industrial areas these days have the requirement to separate or seal machinery components from the various media available in the market. With so many varied
applications existing, with such a large range of requirements, the number of different seal designs and sizes available is vast.
In our global industry, there is a requirement for the constant functionality of seal designs, in all of the different housing types that exist. As a seal manufacturer, Merkel
Freudenberg Fluidtechnic delivers seal with geometries that have been generated using a layout program. Through this, Merkel Freudenberg Fluidtechnic has the possibility
during the laying out of different seal sizes, from the smallest to the largest diameters and profiles, in metric and inch sizes, to meet the high quality expectations of our
customers, as well as enabling us to be able to layouts nearly every seal variation in the quickest possible time.
As an example, here are the procedures carries out when generating a WDR-Radiamatic seal.
Leakage Behaviour of Four-Way Servovalve
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
A. Ellman,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 163-167,
November 1998
view abstract
The paper presents a model for a four-way servovalve which is based on nonlinear modelling of valves' leakage behaviour. The model is identified according to measured flow rate at valve ports and pressure gain curve. The model can take into account some unsymmetry of the valve.
The model is verified in the case of a commercial servovalve.
Leakage Reduction in Fluid Power Systems
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
A. Thatte and B. Yang and R. F. Salant,
2010,
volume 1,
pp. 387-398,
Juni 2010
view abstract
The goal of this project is the development of numerical models of the seals used in fluid power systems, capable of
predicting the key seal performance characteristics, especially seal leakage and friction, and serve as design tools.
Several models of rod seals have been developed so far. These involve elastohydrodynamic analyses, including fluid
mechanics, contact mechanics, deformation, and in some models thermal, components. Some models are steady state,
while others are transient with either elastic or viscoelastic deformation and contact mechanics components. These models have been used to simulate the behavior of a variety of seals including single and double lip U-cup seals,
tandem U-cup seals, step seals and O-rings. In this paper three mixed lubrication models of a reciprocating hydraulic
rod seal are described: a steady state elastic model, a transient elastic model and a transient viscoelastic model. These models are used to simulate a U-cup rod seal utilized in an injection molding application. Results characterizing the leakage and friction force, as well as the detailed behavior of the sealing zone, are presented.
Leak Rate of Seals: Comparison of Theory with Experiment
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
B. Lorenz and Persson, Bo N.J. ,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 37-48,
März 2010
view abstract
Seals are extremely useful devices to prevent fluid leakage. However, the exact mechanism of roughness induced leakage is still not well understood. We present an effective medium theory of the leak-rate of rubber seals, which is based on a recently developed contact mechanics theory. We compare the theory with experimental results for seals consisting of silicon rubber in contact with sandpaper and sand-blasted PMMA surfaces.
Learning Environment for Training the Forest Machine Mechanics
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
T. Palonen and T. Leino and K. T. Koskinen and P. A. Ranta and J. Punki and T. Mäkelä,
2007,
volume 3,
pp. 69-83,
Mai 2007
view abstract
In this paper we describe the theoretical framework and technological solutions of the development of virtual and intelligent learning environment project (ForMecVir). Objective of project is to develop efficiency, quality of instruction and learning and attractiveness to the field of forest machine mechanics. Project will be realized in co-ordination with North Karelia Municipal Education and Training Consortium.
The pedagogical framework presented in this paper supports the development of appropriate learning environment for vocational education of the forest machine hydraulics for mechanics.
The physical modelling of the forest machine boom consists of three cylinders. The proportionally working directional valves controlling the flow to the cylinders include the Load Sensing function that is applied by the use of the variable displacement pump. Three-dimensional dynamic graphics of the hydraulic system will provide essential help for students in understanding functions of the hydraulic system.
Leistungssteigerung pneumatischer Komponenten
M. Fiedler and S. Helduser,
In O+P,
2010,
pp. 256-262,
Juni 2010
view abstract
Der gezielte Einsatz von Simulations- und Optimierungsprogrammen ermöglicht die Entwicklung, Analyse und Optimierung mechatronischer Systeme. Grundlage des modellbasierten Produktentwicklungsprozesses sind detaillierte Systemsimulationsmodelle, welche das statische und dynamische Verhalten nichtlinearer Systeme hinreichend genau abbilden. Die Verwendung von Feldsimulationsprogrammen (CFD, FEM) unterstützt dabei die Bestimmung von Modellparametern.
Life-Cycle Assessment of Oil 'Hydraulic' Systems for Environmentally-Sensitive Applications
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
C. R. Burrows and G. P. Hammond and M. C. McManus,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 61-68,
November 1998
view abstract
Life-cycle assessment (LCA) techniques have been used in order to evaluate the environmental impact of conventional oil 'hydraulic' systems in an ecologically-sensitive application; that of mobile forestry machinery typical of modern European design. A Single-grip 'harvester' employed for logging and a 'forwarder' that subsequently transports the felled and cut-to-length timber out of the forest are analysed. The results of this indicative LCA provide insights into the relative magnitude of the complex range of environmental impacts arising from fluid power systems and their parent vehicles in the forestry context. It also suggests areas for future research, principally on the impact of diesel fuel and hydraulic oil (including their additives) on the forest ecosystem, on the balance between local, regional and global environmental effects, and on the developing methods of LCA itself.
Lifetime Test of New Water Hydraulic Proportional Directional Control Valve
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
F. Majdic and J. Pezdirnik and M. Kalin,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 61-74,
März 2010
view abstract
Besides bio-degradable fluids the tap water is probably the best alternative to protect the environment from destructive pollution. In our Laboratory for power-control hydraulics (LPCH) we have designed, constructed and built up a water hydraulic test rig to investigate the dynamic properties and useful lifetime of the proportional 4/3 water hydraulic directional control valve and of the whole water hydraulic system. Proportional water valve was also newly developed in our laboratory. This proportional valve is spool sliding type of valve. It is constructed that way that we could simply change the material of the spool and the sleeve to investigate tribological and hydraulic properties of the tested material couple in sliding contact. We carried out lifetime test for the first chosen material pair being hardened stainless steel for the spool against hardened stainless steel for the sleeve. The paper shows the change of the leakage flow through time at the duration test and the changes on the sliding surfaces. Duration test was executed with 10 million cycles. The used hydraulic liquid was distilled water; working temperature was in the range from 30 to 35 °C, setting pressure of the pressure relief valve was up to 160 bar, the testing frequency was 5 Hz at the spool amplitude of +/- 100 %. The results show that we can be optimistic about usability of the tested proportional control water valve.
LINEAR ACTUATOR WITH DIFFERENTIAL CYLINDER IN DISPLACEMENT CONTROL FOR THE USE IN MOBILE MACHINERY
17th International Conference Hydraulics and Pneumatics 2001, Ostrava
R. Rahmfeld, M. Ivantysynova,
2001,
view abstract
This paper introduces a new hydraulic circuit for a pump controlled actuator with differential cylinder.
This actuator is especially suitable for future mobile machines and robots. The new displacement controlled
actuator can be operated in open and closed control loop and allows a complex automatic motion
control.
The new actuator concept uses a constant low pressure source for the compensation of the difference
between the in and outgoing flow of the cylinder chambers. Two pilot operated check valves make sure
that the low pressure side of the cylinder is always connected to the pressurized low pressure line. Great
advantages according to the component expenditure are obtained with this new circuit concept, especially
when several linear drives with differential cylinder are coupled where only one pump and one accumulator
are responsible for the pressurization of the connected low pressure lines in a mobile machine.
The main part of the paper describes the control concept and the controller design based on a mathematical
model of the actuator. Further, an implementation on a mobile machine is done regarding required
accuracy, dynamic behaviour and operator feeling. Furthermore, a quasi integrator prevents effects
like limit cycles or wind-up. Measurement results with a standard closed circuit servo pump and a
standard CAN-Bus controller will prove the function of this actuator. By using standard components the
importance of this actuator type for mobile machines will be pointed out.
LINKING CFD AND LUMPED PARAMETERS ANALYSIS FOR THE DESIGN OF FLOW COMPENSATED SPOOL VALVES
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
X. Baudry,
2000,
pp. 249-258,
September 2000
view abstract
The presented work deals with the resort to Computational Fluid Dynamics (CFD) simulation for the design of
flow compensated spool valves. Considering the momentum theory gives very poor results for such
applications, the CFD analysis is involved in the design process to get an accurate estimation of the
mechanical characteristic (Force - Position dependence under various flows) of the moving part of the valve.
As an important extension, a procedure is proposed to get an equivalent lumped parameters model of the valve
hydraulic and mechanical characteristics from the CFD results. By this way, it becomes possible to extract
design rules and black box models to be used for the early prototyping of hydraulic valves. An equivalent flow
jet angle is defined and the flow compensation effect is introduced using a parameter of efficiency that depends
on the valve geometry. Secondly, the CFD analysis is used to analyse the difference between experimental
results and theoretical values in the case of ideal axisymetric flow pattern. It is shown that the flow profile may
change significantly and introduces an additional pressure drop downstream the control orifice. This
additional pressure drop may be used to reduce the flow force. The design methodology is finally validated by
comparison of the experimental and CFD data.
Load Haul Dump Vehicle Kinematics and Control
Peter Ridley and Peter Corke,
In Journal of Dynamic Systems, Measurement, and Control,
2003,
volume 125,
pp. 54-59,
März 2003
view abstract
This paper examines the kinematics and control of a Load Haul Dump Vehicle used in underground mining operations. The aim of the work is to develop an autonomous guidance strategy. A linear, state-space, mathematical model of the vehicle is derived purely from geometric consideration of the vehicle and its desired path. Autonomous regulation of the vehicle is shown to be theoretically feasible using state variable feedback of displacement, heading, and curvature error. A relationship between stability and vehicle speed is derived. This expression forms the basis of an adaptive tuning strategy, which optimizes the vehicle's dynamic response.
Low Ripple Solution: Vane−In−Groove Pump with Precompression.
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
A. Stroganov and L. Sheshin and Y. Volkov and S. Ryadnov,
2007,
volume 3,
pp. 223-231,
Mai 2007
view abstract
Paper presents new approach to pressure ripple and acoustic noise reduction in a vane pump with working chamber located in annular groove of a rotor face (Vane-In-Groove pump) by means of working fluid precompression.
Vane-In-Groove pumps with adaptive rotor comprise means for variation of the volume of working fluid transferred portions and pressure in them. This feature as well as lengthy enough transfer zone makes possible precompressing the transferred portions so that to balance working fluid pressure in them with the output pressure. Thus the origin of decompression impacts eliminates completely.
Two main methods for adjusting the degree of the working fluid precompression are described. The first method works with adjusting the amplitude of the transferred portions volume variation depending on operational pressure and is preferable for reduction of remaining kinematical ripple down to 0.2% and lower. The second method works with adjusting the total transfer angle and is preferable cost wise. One embodiment of the second method was tested and described in details.
The tests equipment, schematic diagram and procedure for output pressure ripple measurement are presented as well as the tests results for 28 cm3 pump. The test results illustrate low levels of output pressure ripple at 500 – 2000 RPM and 10 – 30 MPa.
LUBRICANT PROPERTY AND ROLLING CONTACT FATIGUE TEST OF OIL-IN-WATER EMULSION TYPE HFA-E AND OIL TOTAL AZOLLA 46 AS WORKING LIQUIDS IN HYDRAULIC SYSTEMS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
P. Śliwiński,
2006,
volume 1,
pp. 117-127,
Juni 2006
view abstract
In article are characterized and described results of research (carried out on four-ball machine) of lubricant property
of distilled water, oil-in-water emulsion type HFA-E (1% oil in water) prepared on base of concentrate Isosynth
VX110BF, oil Total Azolla 46 and the pure concentrate Isosynth VX110BF (only in comparison with oil, emulsion and
water). In article are showed results of research (carried out on four-ball machine) rolling contact fatigue tests for
water, emulsion and oil as a means of lubricant also. Furthermore, this article shows results of tribological research of
flat samples made of the same materials as material of parts of working mechanism of hydraulic satellite motors. The
tribological research was conducted using distilled water, emulsion HFA-E and oil Total Azolla 46 as lubricants.
LuGre model-based friction compensation and positioning control for a pneumatic actuator using multi-objective output-feedback control via LMI optimization
K. Khayati and P. Bigras and L.-A. Dessaint,
In Mechatronics,
2009,
volume 19,
pp. 535-547,
Juni 2009
view abstract
This paper deals with a high-friction pneumatic actuator positioning technique based on a LuGre friction closed-loop observer dynamics. The main purpose of the technique is to establish the stability condition by using the passivity of interconnected linear and nonlinear subsystems dealing with the varying and uncertain parametrization of friction modeling and exogenous bounded inputs resulting from the force-loop dynamics. With this formulation, we succeed in designing a full-order dynamic feedback which ensures exponential stabilization and additional multi-objective constraints (an H∞ criterion and a closed-loop pole location). These conditions are expressed in terms of linear matrix inequalities (LMIs). The formulation is therefore numerically tractable via LMI optimization. The performances are validated experimentally on a pneumatic plant operating under a high level of friction. The robust LuGre model-based friction compensator is experimentally compared to other friction compensation and position control schemes.
Machine Fault Diagnosis Using KPCA and SVM
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
M.-Q. Pan and X.J. Zhou and L-Y. Lei,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 621-624,
April 2005
view abstract
As a good classifier, support vector machine (SVM) has higher generalization capabilities than ANN and become a popular tool in many different tasks including the field of machine fault diagnosis. Kernel principal component analysis (KPCA) is a nonlinear PCA developed by using the kernel method and is used for feature extraction. This paper proposes the applications of KPCA to SVM in machine fault diagnosis. Statistical indexes are selected from vibration signal of roll bearings, and then compose original feature volume. Principal components are achieved based on KPCA theory from the statistical indexes and used as the inputs of SVM to perform the classification. The experimental result shows that very high classification rate can be obtained using KPCA/SVM. Compared with PCA/SVM, the former performs better. It also indicates that the combine of KPCA and SVM recognize the fault pattern effectively and has good applied foreground in the field of machine fault diagnosis.
Magnetorheological (MR) damper with a fast response time
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
J. Kostamo and E. Kostamo and J. Kajaste and M. Pietola,
2008,
pp. 169-182,
September 2008
view abstract
It is well known magnetorheological and electrorheological dampers are suitable for semi active vibration control tasks. The fast response time of the MR fluid makes it possible to control vibrations in real time and it has been shown good results in vibration damping can be achieved and the performance of the semi active method is almost comparable to active damping in some cases.
Typically MR dampers have been applied in vibration damping at relatively low frequencies ranging from almost static conditions up to about some 10Hz. Based on recent research results the real time controllable bandwidth of MR technology in semi active vibration control could be much higher than that has been generally reported. In this article a high frequency magnetorheological valve has been combined with a hydraulic cylinder to form a semi active damping device. The main design criteria for this kind of device are given in this article and an experimental device is built to verify the performance. The performance of this combination will be analyzed and the experimental results are compared with theory.
Magneto-rheological valve-integrated cylinder and its application
K. Yoshida and T. Soga and M. Kawachi et al.,
In Proc. of the Institution of Mechanical Engineers Part I, Journal of Systems and Control Engineering,
2010,
pp. 31-40,
view abstract
This paper presents a novel magneto-rheological (MR) valve-integrated cylinder and its use in manipulator operations. Conventional MR valves are flow channels that have magnetic poles and control MR fluid flow by using the apparent viscosity change created by the application of a magnetic field. The proposed MR cylinder consists of an electromagnet-mounted piston with an annular gap, a cylinder made of magnetic material, and an upstream restriction. The MR valve has an electromagnet which controls the differential pressure of a piston and the output force. The MR cylinder features a simple, compact, and low-cost structure, a long stroke, robustness against dispersed particles, a high output force that is sufficient to drive mechanical systems, and easy force control. Furthermore, in this study, to decrease fluid power loss in pipelines, a novel low base viscosity MR fluid is created by the use of low-density ferrite particles. The basic characteristics of an MR cylinder using the new MR fluid are experimentally evaluated utilizing a fabricated MR cylinder mounted onto a manipulator. Based on these results, optimally designed MR cylinders are mounted onto a manipulator and the basic validity of the system is experimentally confirmed.
Mapping of large scale fluid power system simulations on a distributed memory parallel computer using genetic algorithms
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
K. Pollmeier and C. R. Burrows and K. A. Edge,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 83-91,
November 1996
view abstract
Parallel simulation of fluid power systems using the
transmission-line modeling method offers the benefit of increased speed of execution, but requires the system model to be partitioned on to individual processors [Burton, 1994].
In this paper we address the automatic placement of component models on processors of a distributed memory parallel machine. A genetic algorithm is used to map the different processes onto several processors. The objective is to minimise the total processing time in order to achieve real time performance. For fine grained computation problems
the communication time cannot be neglected, i.e. we
consider the computation and the communication time of each task. This mapping problem is a combinatorial optimization
problem which can be reduced to the graph partitioning problem which is shown to be NP-complete.
Combining genetic algorithms with heuristics leads to optimal or very good sub-optimal solutions. A hydraulic example circuit is partitioned in four and eight subsystems, respectively, and the simulation is implemented on a Transputer based platform. Using eight processors a speed up of 3.7 was achieved.
Mass Conservative Modelling of Resistances in Fluid Power System Simulation
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
C. Riedel and C. Stammen and H. Murrenhoff,
2010,
volume 1,
pp. 227-236,
Juni 2010
view abstract
This article illustrates the development of a dynamic system simulation tool for fluid power systems based on mass
flows. State of the art simulation tools make use of simplified differential equations. Especially in closed systems or
long-term simulations, the volume flow based approach leads to significant variations of simulation results as
balancing of flow parameters and their integration to potentials lead to a violation of the equation of continuity. The
goal of the project “mass conservative system simulation” which is funded by the German research foundation is to
increase the predictability and efficiency of system simulation tools in fluid power. A mass flow and energy conservative
approach leads to a physically correct model that is implemented exemplarily in the simulation tool DSHplus.
At first this article gives a short introduction into fundamental equations of mass conservative lumped parameter
simulation, which is based on hydraulic capacities for calculation of pressure build-up, inductivities for inertia and
resistances for pressure losses.
Furthermore, new approaches for lumped parameter modelling of mass flow through hydraulic resistances are
discussed. So far only pure laminar (throttle) or turbulent (orifice) flows can be specified. In many cases this is not
adequate, especially if temperature influence has to be considered. The absolute pressure dependency of mass flow due
to density changes and critical flow due to cavitation is not accounted for until now, either. Without consideration of
these influences a mass conservative modelling is not possible. The results are obtained empirically by experiments
using a special test rig, by CFD simulations as well as analytically. The overall goal is to generate models that can be parameterised simply on basis of dimensions from data sheets to allow a better usability.
Mathematical Analysis of Stability and Drift Behavior of Hydraulic Cylinders Driven by a Servovalve
Edouard Richard and Jean C. Vivalda,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 206-213,
März 2002
view abstract
Hydraulic cylinders are commonly used and many works deal with modeling and control of such devices. This article deals with the stability properties of hydraulic cylinders drift in various situations. The study is based on a classic nonlinear model of these physical systems. The cases of system models without leakages and models with cylinder leakages or servovalve leakages are distinguished and lead to distinct behaviors. The stability properties are proven by various mathematical arguments such as first integrals, Lyapunov theorems, LASALLE invariance principle, BARBALAT's lemma, and the center manifold theory.
Mathematical Modeling of a Two Spool Flow Control Servovalve Using a Pressure Control Pilot
Randall T. Anderson and Perry Y. Li,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 420-427,
September 2002
view abstract
A nonlinear dynamic model for an unconventional, commercially available electrohydraulic flow control servovalve is presented. The two stage valve differs from the conventional servovalve design in that: it uses a pressure control pilot stage; the boost stage uses two spools, instead of a single spool, to meter flow into and out of the valve separately; and it does not require a feedback wire and ball. Consequently, the valve is significantly less expensive. The proposed model captures the nonlinear and dynamic effects. The model has been coded in Matlab/Simulink and experimentally validated.
Mathematical modelling and experimental characterization of a high dynamic servo valve integrated with piezoelectric actuator
S. Karunanidhi and M. Singaperumal,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2010,
volume 224,
pp. 419-435,
view abstract
A conventional two-stage servo valve basically consists of an electrically operated torque motor as the first stage and spool valve as the second stage. Owing to the limitation in the band width, servo valves are not suitable for high-frequency applications. The work presented in this paper deals with the methodology of the mechatronics approach for the design of a piezoelectric actuator with a mechanical amplifier and its integration into a servo valve. The analysis and simulation of a multilayer piezoelectric actuator (MLA) a with mechanical amplifier for high-frequency application has been done using icon-based bond graph technique and finite element coupled field analysis for the commercially available piezoelectric actuator. The designed piezoelectric actuator was integrated into an existing flapper-nozzle servo valve by replacing the first stage. The dynamics of the valve integrated into a piezoelectric actuator has been simulated. The required simulation parameters for the actuator have been derived from a finite element model. An experimental set-up has been carried out to determine the no-load flow gain of the valve. Also the time response has been measured for a conventional servo valve and servo valve with piezoelectric actuator. The designed valve with a piezoelectric actuator has satisfactory static and dynamic characteristics for high-speed applications.
Mathematical modelling and simulation of sliding contact vane / profiled stator of vane pump
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
R. Petrović and A. Banaszek and A. Vasilev and S. Batoćanin,
2010,
pp. 249-262,
September 2010
view abstract
Sliding contact vane/profiled stator in vane pump with double effect is described via its characteristic traits. The complete mathematical description of one such contact in the present paper was possible through the application of the following expressions and equations: continuity equation, clearance geometry, deformation equation, energy equation and expression for physical characteristics of working fluid. ln the paper, a sufficiently accurate model has been carried out for elastohydrodynamic line contact [2] .
For forming the mathematical model, the following assumptions were introduced: only the two-dimensional case was observed, parameters don’t depend on time, the working medium is newton fluid, inertia forces were disregarded in comparison to friction force, viscosity and thickness of working medium depend only on pressure and temperature, surfaces of parts in contact are ideally smooth, the working medium sticks to the surface, the surfaces of parts in contact become deformed elastically in semi-space, deformations caused by temperature change are disregarded and heat flux (flow) comes and is applied directly onto the surfaces of parts in contact [1].
By applying the mathematical model in original simulation program KRILP, developed for prototype of vane pump with double effect type 641- 4300, by PPT Trstenik company, Serbia, it is possible to analyze mutual influence of the following parameters on the pump’s work: pressure, clearances, temperatures, viscosity in slide pair vane/profiled stator. Analysis may yield a completely new construction of prototype or entire family of vane pumps [3].
MATHEMATICAL MODEL OF THE VALVE CONTROLLED SKID STEERED MOBILE MACHINE
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
M. Hyvönen and J. Vilenius and A. Vuohijoki and K. Huhtala,
2006, August 2006
view abstract
Today, all types and sizes of hydraulically operated mobile machines are widely used for all kind of purposes. However,
the number of remote operated mobile machines has been quite small due to the lack of telecommunication devices
needed. Nowadays when telecommunication technology has developed rapidly it is possible to apply it costeffectively
in the area of mobile machines, too. This will raise many new challenges also in the field of hydraulic machine
design. For example, because there is no force feedback of the machine to the driver, an accurate and smooth
control of the machine is essential to achieve sufficient stability and performance. These and other important design
parameters can be studied more easily with virtual prototyping. A virtual prototype of a skid steered mobile machine is presented in this paper.
Measured Characteristics of an In-line Pump with Independently Controlled Pistons
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
J. Tammisto and M. Huova and M. Heikkilä and M. Linjama and K. Huhtala,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 361-372,
März 2010
view abstract
The importance of the energy economy has been increased recently. One of the driving forces to this development has been the legislation which concerns emissions and pollution. These facts have also been behind this research work. This paper deals with originally constant flow pump. The studied unit is a three piston in-line pump. The unit has been modified piece by piece to variable displacement pump by means of active controlled electrical on/off-valves. The effects of different parameters to the efficiencies of the pump have been measured and the results are presented. The measured results of the modified pump have been compared to the measured results of the original pump. The results show that the presented digital pump is competitive compared to traditional units and is capable of controlling the average flow rate.
MEASURED PERFORMANCE EVALUATION OF PID AND NEURAL NET CONTROL OF A HYDRAULICALLY DRIVEN INERTIA LOAD WITH NONLINEAR FRICTION
W. Qian and G. Schoenau and R. Burton,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 31-36,
März 2001
view abstract
Hydraulic systems are inherently nonlinear. When used to control an inertial load, which also exhibits nonlinear behaviour due to slip-stick friction at the contact surface, the result is a system which is highly non-linear and poses a difficult control problem. The study described in this paper examines the experimental performance of velocity control of
a mass on a sliding contact surface using a servovalve and linear actuator. Conventional PID control is compared to
artificial neural net (ANN) based controllers. A modified multi-input PID controller was used to train the ANN controller.
The ANN based controller outperformed the PID controller when subjected to a wide variety of input signals. A second ANN co-controller was added to the loop to provide an additional corrective signal in the form of a pulse to give
the system an extra surge of input to overcome the stiction friction in the zero velocity cross-over region. Excellent results were achieved with improved accuracy compared to the single ANN controller when subjected to a series of random
input signals, indicating the robustness of the ANN controllers.
Measurement of the Dynamic Properties of Hose Walls Required for Modelling Fluid-Borne Noise
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
D. K. Longmore and D. N. Johnston,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 105-111,
November 1997
view abstract
Methods are presented and examined for obtaining the dynamic material properties of a hose wall under realistic conditions. The properties have been used in mathematical models of fluid filled hoses with and without tuners inside in order to calculate pressure ripple in hydraulic circuits and to seek to minimise the associated noise. The material properties are derived from measurements of an impedance matrix relating pressure and axial wall compression to flow and axial wall velocity at each end of the hose.
Measurements, Analysis and Simulation of Cavitation in an Axial Piston Pump
6.IFK Dresden
O. Meincke, R. Rahmfeld,
2008,
volume 2,
view abstract
The goal of this paper is to provide measurement results which show cavitation in a closed circuit axial piston swash plate type pump, and to describe ways how this cavitation effect can be reliably predicted in order to optimize products (valve plates) already in an early design phase. The physical effect of cavitation is still an issue in hydrostatic units, also in closed circuit, and especially under extreme conditions. Moreover, the starting point of cavitation and the location of erosion are still very difficult to predict by theory or simulation, so that long term tests or field results are normally needed for analysis.
This paper presents measurements of high frequency pressure ripples due to cavitation, directly in the steering groove of a valve plate. It will be shown how a suitable pressure sensor has been im-plemented in the endcap of an axial piston pump in a way, that the measuring membrane is located directly in the beginning of a steering notch. This is the nearest location to the cylinder block and ideal for measuring the dynamics of the pressure due to the rotation of the cylinder block.
The used analysis to extract the high frequency “cavitation” signal from the piston frequency will be derived. Results for different operating conditions will be shown. In addition, acceleration and opti-cal (high speed video) measurements have been done, and some will be also described or given in the presentation, respectively. It will be concluded which measurement strategy has to be chosen for indicating cavitation effects experimentally.
The pump, including a special cavitating valve plate, has been model in a customized CFD envi-ronment. The corresponding simulation results will be shared which prove that in case of a suitable cavitation module, and by regarding multi-phase flow and compressibility, the measured effect can be repeated. It has to be mentioned that both investigations, measurement and CFD simulation, were done in parallel without sharing the results between each other.
Mechanics of submerged jet cavitating action: material properties, exposure time and temperature effects on erosion
E. A. F. Hutli and M. S. Nedeljkovic and N. A. Radovic,
In Archive of Applied Mechanics,
2008,
volume 78,
pp. 329-341,
Mai 2008
view abstract
Experimental setup with a submerged cavitating jet has been used for the study of influences of material, exposure time and working fluid temperature on the erosion process. Each of the parameters has been varied separately, and the results of erosion are analyzed in detail. Additionally, comparison of experiments with nitrated and non-nitrated material has been made in order to study the enhancement (mostly reflected as the prolonged incubation time) of erosion resistance achieved by nitration the specimen surface.
Mechatronic Model and Experimental Validation of a Pneumatic Servo-Solenoid Valve
Massimo Sorli and Giorgio Figliolini and Andrea Almondo,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
September 2010
view abstract
This paper deals with a method for static and dynamic modeling of a three-way pneumatic proportional valve actuated by means of a proportional solenoid, which can be applied in robust design, condition monitoring, and development of advanced control strategies. Test-beds for the experimental identification of the main physical parameters of the valve are described along with the proposed experimental methods. A mechatronic dynamic model of the valve is then presented, which considers the servo-solenoid as the electromagnetic subsystem, the moving parts of the valve as the mechanical subsystem, and the fluid parts for flow-rate control as the pneumatic subsystem. Finally, the proposed mechatronic dynamic model is validated by comparing the experimental and simulated diagrams for adsorbed current, spool position, and instantaneous flow-rate.
Metering poppet valve system control
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
C. Harvey and O. Cline and R. Fales,
2007,
pp. 283-296,
September 2007
view abstract
Metering poppet valves are being developed to regulate flow in place of more common spool valves. This is due to certain advantages offered by metering poppet valves. However, these advantages cannot be fully realized until control design challenges involving stability and performance are solved. A design for a two-stage metering poppet valve is presented. For control, several researchers have used feedback linearization to cancel part of a hydraulic system’s nonlinearities in spool valves. In this work, nonlinearities are cancelled in the input-output relationship of the metering poppet valve. Reference tracking of the flow is analyzed.
METHOD OF CHARACTERISTICS FORMING OF THE MULTIFUNCTIONAL HYDROSTATIC MACHINE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Banaś,
2008,
pp. 431-434,
Juli 2008
view abstract
The paper presents the method of forming the steady-state characteristics of multifunctional hydrostatic machines. This
is a six steps process which combines the mathematical model and the findings of the experimental research. The paper
is focused on the rotary spool valve as the important part of the machine, especially on the gap between the shaft and
the spool. By using this method it is possible to improve the design of the machine.
METHODOLOGY FOR THE MINIATURIZATION OF HYDRAULIC COMPONENTS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
D. Huguet and E. Codina Macia,
2002, Juli 2002
view abstract
The study reported in this paper forms part of a project aimed at improving mini-hydraulic components technology. In
order to respond to the current demands for mini and micro power hydraulic equipment, we need to increase the
pressure and reduce the size of the hydraulic components. The difficulties to know the flow configuration though a
valve are important. The flow valve depends of the valve geometry, the fluid properties and the operation conditions.
Different kinds of flow, reattached and separated can appear. The pressure and force characteristics, the influence of
cavitation, and the apparition of noise are other important problems that have to be taken into consideration. All of these
aspects will be studied with the help of a test bench and CFD software. Experimental visualization has allowed us to
follow the flow configuration and the apparition of cavitation. These results will be compared with the simulation. The
effects of valve parameters are investigated and the modelling can help identify specific problems and yield insight into
stable designs. The valve studied has been a DIRECT ACTING RELIEF MINIVALVE.
METHODOLOGY OF DESIGN INTERNAL INVLOUTE GEARS APPLIED TO THE FLUID POWER PUMP
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
T. Greczanik and J. Stryczek,
2006,
volume 1,
pp. 205-217,
Juni 2006
view abstract
In the paper has been described the basics of design set of internal involute gears, applied to fluid power pumps.
The authors have presented design methodology of that pumps taking: geometry, kinematics, manufacturing and
fluid effects into consideration. It has been prepared procedure, step by step, how to select gears parameters and
it has been determined the usefulness limits of those. Also it has been taken note of the most frequent problems
during designing as: tooth undercutting, interference of teeth heads or noise emission the pump. It has been
presented some methods to eliminate those failures. Finally it has been presented some research results of
involute internal spur-gear pump as: efficiency, pressure and noise emission.
Micro Actuators Using Functional Fluids and the Systems
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Yokota and K. Yoshida and K. Edamura,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 71-76,
April 2005
view abstract
Actuators are one of prime important mechanical components in order to construct electro-mechanical systems. Particularly, in micro systems like in-pipe micro-machines, micro factories, it is required to develop powerful micro actuators for realizing practical works. Fluid power system has a potential to develop active and functional components in the field of micro-machines. Here, from the view point of the powerful micro actuators for advanced micro fluid control systems, advanced fluid control elements like micro valves, micro motors and micro pumps are developed by using functional fluids like ERF, MRF and ECF in our laboratory. These functional components developed in our laboratory are
briefly reported.
Micro Control Valves by Making Use of Electro-Rheological Fluids (Control of one-link manipulator with the micro ER valve)
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
Y. Kondoh and S. Yokota,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 55-60,
November 1997
view abstract
A three-port micro control valve by making use of electro-rheological (ER) fluids is proposed and fabricated, whose size is 12x12x12mm. Static and dynamic characteristics of the micro valve are examined. The valve can produce load pressure change of 0.35MPa at maximum electric field strength of 5kV/mm. In addition, the micro valve is applied to control a one-link manipulator with a small-sized artificial rubber-muscle-type actuator. The effectiveness of the micro valve is experimentally demonstrated for use in fluid servo systems.
Microflow valve control system design
R. Zante and X. T. Yan,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2011,
volume 225,
pp. 431-442,
Mai 2011
view abstract
A design synthesis for a microflow control system is presented based on the interrogation of an analytical model, testing, and observation. The key issues relating to controlling a microflow using a variable geometry flow channel are explored through the implementation and testing of open and closed-loop control systems. The reliance of closed-loop systems on accurate flow measurement and the need for an open-loop strategy are covered. A valve and control system capable of accurately controlling flowrates between 0.09 and 400ml/h and with a range of 900:1 is demonstrated.
MICRO MECHATRONICS SYSTEM USING FUNCTIONAL FLUID POWER - DESIGN AND FABRICATION OF MICRO PUMP AND CONNECTING TUBE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
M. Ebisawa and Y. Tanaka and N. Tanaka,
2008,
pp. 285-293,
Juli 2008
view abstract
A prototype model of micro pump module for micro fluid power actuation systems is fabricated and experimentally
investigated. The functional fluid; ECF (Electro-Conjugate Fluid) is used to be pumping function for the micro pump
module of the fluid power actuation system. The fluid power source using the ECF can be embedded in the main body of
the micro fluid power actuation systems and can be effective as driving source of the actuator. In difficult assembly of
mechanical elements, a stereolithography method is used to form the entire micro fluid power actuation systems in allin-
one design including actuators, pumps, valves and connecting tubes. Some kind of a novel needle-type of micro
electrode in the pump module is fabricated by a micro electric discharge machining. The connecting tubes between the
pump and actuator modules are important fluidic parts for the micro mechatronics system using fluid power.
Micro sensors on flow detection of hydraulic system
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
Z. Hongpeng and S. Yuqing and C. Haiquan,
2004,
pp. 623-626,
Juni 2004
view abstract
MicroElectroMechanical Systems (MEMS) sensors are widely used in many fields for their exclusive features. It will also be applied in hydraulic flow detection in the future. The feasibility is discussed on microsensors, communication technology and planting strategy in this paper. A conceptual design in which a pressure sensor, a temperature sensor, a micro-controller, a communicating unit are integrated on a centimeters squared printed circuit board (PCB) is presented. A group of PCBs lined on the inner wall of hydraulic pipe constitute a flow sensor. Compensated by temperature, flow rate can be calculated from the measured pressure gradient. We have gained an optimized distribution strategy.
Miniature Parallel Handling Machine for Future Microfactory
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
M. Juhairi Aziz Bin Safar and K. Ichiryu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 695-699,
April 2005
view abstract
This paper presents a new Microhand that developed by using parallel mechanism concepts for Microfactory [1] Machine. Several serial mechanisms were examined, but none could fulfill the requirements of high precision. Therefore, as regard to the required three degree of freedom (3-DOF) and high precisions, 3 axes of parallel mechanism [2, 3] had been chosen. Dealing with micro sized object, it was not necessary for using more than two fingers. It is enough by using only two fingers just like chopstick. Therefore, two 3-DOF parallel structures were needed.
In order to design compact structures and an efficient work space, the parallel structures should to be well designed. It is disadvantages if the parallel were line up in a row, but it will be advantages if the platforms were arranged on the same z-axis.
Regarding to the compact design, it was designed as outer and inner platform at the same level. Outer platform is in donut shape, and another one in circle shape that is mounted inside of it. On each platform a pin as a finger was fixed. Each platform can only move though z-axis and rotation at x-y axis. With this three basic movements object can be nab and release at a certain distance. It is possible for this machine to manipulate micro sized object. Improving certain point such as improving structures and programming would lead this machine to manipulate smaller sized object in the future.
Miniaturized Bistable Seat Valve
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
J.−P. Uusitalo and T. Lauttamus and M. Linjama and L. Söderlund et al.,
2007,
volume 3,
pp. 379-391,
Mai 2007
view abstract
To make digital hydraulic systems competitive the volume of existing solenoid valves should be reduced to about a half. Thus, the development of a small, fast and low
power on/off valve is one of the key issues in modern digital hydraulics. So far, digital hydraulic systems have been implemented using traditional solenoid valves which are in
general big and slow. A particular problem with seat valves has been the spontaneous closing due to pressure difference over the opened valve. In this work, a new seat valve
design using several restrictions and bistable electromagnetic actuator is described.
Hydraulic and electromagnetic parts have been designed together in order to minimize the size of the valve. The electromagnetic actuator uses permanent magnets to achieve bistable properties, which means work is needed only to change valve state. The
valve as a whole is designed using results from both hydraulic and electromagnetic computations. The valve actuator is modelled using CEM and the hydraulic part of the valve is modelled using CFD. Experimental results include the properties of the actuator and the valve. Results show significant reduction in volume and response times.
MINI – EXCAVATOR PERFORMANCE PREDICTION AND VERIFICATION THROUGH EXPERIMENT
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
E. Hughes and M. Ivantysynova,
2008,
pp. 479-479,
Juli 2008
view abstract
Simulation and analysis are used to predict machine performance and efficiency during design, but often there
exists large discrepancies between actual experimental results and analytical results. In order to reduce fuel
consumption in a period of rising energy costs, the hydraulic system of a mini-excavator is being re-thought. The
traditional load-sense, resistance controlled, circuit is being replaced with displacement controlled actuators,
eliminating the throttling losses inherent to valves. The design process began with a coupled kinematic-hydraulic
model of the load-sense excavator. The model was used to locate the specific areas of energy consumption and
demonstrate the possible savings. As with all models the entire physics could not be captured, and thus it was
necessary to validate the simulated results by comparing them with experimental data.
MOBILE MACHINERY BASED ON NEW DISPLACEMENT CONTROLLED LINEAR ACTUATOR TECHNOLOGY
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
Robert Rahmfeld,
2002, Juli 2002
view abstract
This poster presentation deals with the transference of the new displacement controlled linear actuator technology onto overall mobile machine systems for working hydraulics based on differential cylinder. The new actuator concept uses a constant low pressure source for the compensation of the difference between the in and outgoing flow of the cyl-inder chambers. Two pilot operated check valves make sure that the low pressure side of the cylinder is always con-nected to the pressurized low pressure line. Great advantages according to the component expenditure are obtained with this new circuit concept, especially when several linear drives with differential cylinder are coupled on the low pressure side where only one common low pressure source is required in a mobile machine system. The presentation will clearly indicate an enormous system simplification in contrast to today’s valve controlled LS (load-sensing) systems. This leads to reduced machine installation and maintenance costs and an improved reliability. Considering the strong trend of more automation in the area of mobile machines takes the task of active oscillation damping into account for this actua-tor technology. Due to a simple control system and the recovery of load and brake energy a strong motivation for the displacement controlled actuator technology can be proved for this automatic function in contrast to valve control.
Modal Approximation of Distributed Dynamics for a Hydraulic Transmission Line With Pressure Input-Flow Rate Output Causality
Beshahwired Ayalew and Bohdan T. Kulakowski,
In Journal of Dynamic Systems, Measurement, and Control,
2005,
volume 127,
pp. 503-507 ,
September 2005
view abstract
Based on analytical results obtained in the frequency domain, modal approximation techniques are employed to derive transfer function and state space models applicable to a pressure input-flow rate output causality case of a transmission line. The causality case considered here arises while modeling short connection lines to hydraulic accumulators. However, the modal approximation results presented apply also to other cases where the linear friction model is considered applicable. It is highlighted that the results presented can reduce the overall order of the hydraulic system model containing the transmission line being considered.
MODAL CHARACTERISTICS OF A HYDRAULIC CYLINDER AND THEIR VARIATION WITH ROD EXTENSION
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
F.M. Monroig and H. Sumali and B. Yagci,
2002, Juli 2002
view abstract
Modal properties of an oil-filled hydraulic cylinder are obtained experimentally using a force
transducer, accelerometers, a Fast-Fourier-Transform analyzer, and modal analysis software. Three
models where used to study the vibration characteristics of the cylinder: Barrel, Rod and Combined.
The eigenvalues and mode shapes are mostly complex; apparently the rubber seals and the oil introduce
non-proportional damping. When the rod is extended, not all natural frequencies decrease. When the
barrel and the rod were modeled separately they exhibit a beam-like vibration behavior. The Combined
model showed a jump or discontinuity that occurred between the barrel and rod test points which
indicates that the cylinder components may need to be modeled apart. The mode shapes of the rod are
either dilated with extension or change into more complicated shapes as the rod extends. The results
obtained in this investigation will be used as a starting point to develop mathematical models of the
hydraulic cylinder for control purposes.
Model-Based Estimation of Internal and External Forces on a Hydraulic Cylinder
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
K. Kashi and D. Söffker,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 607-611,
November 2003
view abstract
One of the more complex influences on a hydraulic cylinder is the friction force acting
between the cylinder piston and the housing. This is the main nonlinearity in the cylinder,
which is usually not measurable. Another force acting on the cylinder is the external force,
which is desired but usually not measured. This is especially the case in automotive
applications since additional sensors increase the cost of the system and also lead to
installation and packaging issues. In this contribution, a model-based technique is used
to estimate these forces as a sum, acting on the cylinder piston.
The paper introduces the Proportional-Integral-Observer (PIO) approach to estimate the
forces using only a few easy-to-have measurements. As a result of this approach, beside
the cylinder forces also the piston travel and velocity can be estimated.
Modeling a hydraulic uniaxial drive system is described in numerous papers and books
in the arrangement [1] illustrated in Fig. 1. The system consists of a translatory drive, a
proportional valve and a coupled mass m.
The system inputs are the system pressure and the valve input voltage. The output is
the cylinder travel. Other states of interest are both cylinder chamber pressures.
In this contribution the interest is focused on the hydraulic cylinder, therefore the servo
valve is neglected and the volume flow to each cylinder chamber are used as the inputs
of the system. The choice of the output vector depends on the available or desired
measurements, which in this case are the chamber pressures.
The friction forces and the external force are added to represent the total force acting
on the cylinder piston. Leakages between the cylinder chambers as well as external oil
leakages are neglected in this consideration, since their influence on the cylinder dynamics
are minimal. For the model-based description used for PI-observer design the nonlinearities
described in the previous chapter are neglected, hence the model has to be simplified
for the linear observer design. The moving mass, the oil bulk modulus are assumed to
be constants and both chamber volumes are assumed to be constants and equal. Also
the switching functions, for the volume flow equations, are approximated as analytical
arctan-functions.
Model Based Parameter Identification of a Fluid Power Component
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2002
B. Manhartsgruber and J. Mikota,
Professional Engineering Publishing,
ed. C.R. Burrows and K.A. Edge,
2002, September 2002
Model-Based Pressure and Torque Control for Innovative Pneumatic Soft-Actuators
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
A. Wilkening and M. Mihajlov and O. Ivlev,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 291-302,
März 2010
view abstract
This paper describes a model-based pressure and torque control concept for innovative pneumatically driven actuators with rotary elastic chambers. These soft-actuators have been developed to operate in human environment, especially for physical interaction with people in service and rehabilitation tasks. Owing to the inherent compliancy of the working chambers, these actuators possess additional (compared to conventional fluidic actuators) nonlinearities, causing specific problems related to their modeling and control. The pressure and torque control concepts were investigated and tested by using a knee motion therapy device as test-bed. The torque control is used to compensate the weight of the device mechanics as well as the patient’s lower leg. Next step is the realization of "Assist-as-Need" behaviour for rehabilitation tasks.
Model-Following Controller Based on Neural Network for Variable Displacement Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. Kuisheng and H. Ilao and R. Zhijun and L. Guanglin and L. Yuanhui,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 28-31,
April 2005
view abstract
The Electro-hydraulic proportional variable displacement axial piston pump (VDAPP) is widely used in heavy-load pump control system, which is inherently nonlinear, time variant and subjected to intensive disturbance.
In this paper, a neural network model-following controller is proposed to approach the nonlinear anti-model of the object, and to realize the control of electro-hydraulic swashplate angle and flow, so that the uncertainty and nonlinear of the system can be compensated, The results of simulation and experiment show that the proposed neural network controller can conduct nonlinear control in VDAPP, enhance adaptability and robustness, and improve the performance of the control system.
Modeling and Comparative Investigation of a Tritec Power Unit
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
S. Raghibizadeh and A. Kapps and A. A. Goldenberg,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 83-92,
November 1997
view abstract
This paper presents the results of comparative analyses between the TriTec Power Unit and a typical crank type air motor based on their mathematical models. The comparative analyses showed that the efficiency of the TriTec Power Unit is superior to that of a comparable conventional crank type motor. A representative value for the improvement in efficiency is 50%. A number of case studies have been considered in our investigation in order to assess performance of the motors under various combinations of working conditions that may occur in practice. In all of the cases studied, the efficiency of the TriTec Power Unit has been superior to that of the crank type motor.
MODELING AND CONTROL OF A DUAL-SOLENOID ACTUATOR FOR UNSTABLE VALVE
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
Q. Yuan and P. Y. Li,
2004,
pp. 463-472,
Juni 2004
view abstract
Unstable valve is a new concept that is concerned with implementing fast responsive
and cost effective single stage direct acting electrohydraulic valves. The main issue is
that in high ow rate and high bandwidth operations, the force and power required of the
solenoid actuator for stroking the spool become prohibitive. Our approach is to utilize ow
force induced instability to enhance the spool agility, so that the demand on the solenoids
can be alleviated. However, the open loop instability and the nonlinear nature of the valve
make the controller design more challenging. In this paper, a sliding mode controller is
designed to stabilize the system and to achieve the displacement trajectory tracking. A
case study validates the controller. The simulation also shows that this control scheme
provides unstable valves with a benet of saving the electrical energy.
Modeling and Control of a Portable Powered Ankle Foot Orthosis
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
Y. Li and A. Shorter and T. W. Bretl and E. T. Hsiao-Wecksler,
2010,
volume 1,
pp. 127-141,
Juni 2010
view abstract
A preliminary design for a portable powered ankle foot orthosis (PPAFO) was previously developed using off-the-shelf
pneumatic components to explore new opportunities for fluid power in human assistive devices. The untethered
pneumatically powered PPAFO provides both motion control and external torque assistance at the ankle via a binary,
event-based control scheme that uses solenoid valves. While stable, this design approaches results in limitations to the
overall performance of the system. This paper presents a modeling and control approach that seeks to address the
limitations of the current method. Hardware and control configurations were evaluated using simulations of the
modeled PPAFO and ankle/foot system during three functional gait tasks: (1) velocity control of the foot at the start of
the gait cycle, (2) torque assistance for propulsion and stability at the end of stance, and (3) position control of the foot during swing. Computational models of the PPAFO/leg system showed that the introduction of a proportional valve
along with new control architecture, resulted in PPAFO performance and efficiency improvements in simulation.
Modeling and experimental research of characteristic parameters hydrodynamic processes of axial piston pumps with constant pressure and variable flow
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
R. Petrovič and N. Todič,
2008,
pp. 278-285,
September 2008
view abstract
Axial piston pumps with constant pressure and variable flow have extraordinary
possibilities for controlling the flow by change of pressure. Owing to pressure feedback,
volumetric control of the pump provides a wide application of these pumps in complex
hydraulic systems, particularly in aeronautics and space engineering.
Mathematical modelling is the first phase in defining the conception of a design and it has
been carried out at the beginning of the project. Next very important phase is the check-out of
the characteristics at the physical model when the pump has been produced. Optimal solution
to the hydropump design has been reached by thorough analysis of the parameters obtained
at the physical model by means of the simulation results of the mathematical model.
The paper presents the possibilities for selecting the most influential parameters, their
correction for certain values, and eventually the simulation at the mathematical model which
shows the change of hydropump performances. After all these analyses, the appropriate
changes are done in design documentation which will serve for prototype production. Finally,
when all kinds of tests are done at the prototypes along with fine adjustment of design
solution, the series production of hydropump will be organized.
Modeling and Identification of a Pneumatic Muscle Actuator System Controlled by an On/Off Solenoid Valve
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
V. Jouppila and A. Gadsden and A. Ellman,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 167-182,
März 2010
view abstract
Pneumatic actuators offer desirable properties for many applications, such as compactness, low costs, high power-to-weight ratios, reliability, and simplicity. However, due to many nonlinearities (air compressibility, friction, air flow through valve), accurate position and force control of pneumatic actuators is extremely difficult and expensive to achieve. There is a growing interest in PWM-controlled pneumatic systems using low cost on/off solenoid valves instead of servo valves in order to develop less expensive
pneumatic servo systems. In addition, a new type of pneumatic McKibben muscle actuator possesses significant advantages like a very high force/weight and force/volume performance, quick response, and wide operational ranges in a variety of environments.
In this paper, a high speed on/off valve is applied to control a pneumatic McKibben muscle actuator system. However, the complex nonlinear dynamics of the actuator in addition to those already mentioned make the modeling and accurate control of the pneumatic system a difficult challenge. As a result, the designed model is nonlinear and may still contain unknown parameters that require identification in order to obtain reasonable dynamical matching with the real system. Furthermore, the discontinuous switching nature of the on/off valve causes transients in the system, making the analytic modeling of the system even more complex.
The objective of this research is to develop an analytical model of the system which includes the nonlinearities of the system, and the transformation of the discontinuities into a continuous form. The use of analytical models enables the implementation of conventional analytical control approaches, such as sliding mode control, and provides a tool for the analysis of stability and robustness. In this paper, the
modeling process is applied to a one degree of freedom pneumatic system for which the analytical nonlinear system model is developed by a combination of physical and empirical methods. An extensive set of experimental tests are performed to characterize the dynamics of the overall system. A non-analytic and analytic model of the system are developed and validated by a comparison of the simulated results with the experimental implementation of the system.
Modeling and Identification of Hydraulic Servo-Valves
Structural Control: Proceedings of the First European Conference, Barcelona, Spain, 29-31 May 1996
ISBN: 981-02-3019-2,
H. Aberl and R. Karan and R. Scheidl,
World Scientific Publishing,
ed. A. Baratta and J. Rodellar,
1996,
pp. 386-393,
view abstract
A detailed mathematical model for a hydraulic servo-valve with a flapper-nozzle pilot-stage is of sixth order. This model requires numerous data which to a great part must be taken from extensive experiments. By singular perturbation arguments the order can be reduced at least to three in many cases even more to one. The coefficients of this reduced models can be determined fom the step response- and frequency-response curves, which are provided as normal data in the manufacturer's valve-catalogues.
Modeling and Identification of Lubricated Polymer Friction Dynamics
Geesern Hsu and Andrew E. Yagle and Kenneth C. Ludema and Joel A. Levitt,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 78-88,
März 2000
view abstract
A systematic approach is proposed to model the dynamics of lubricated polymer friction. It starts with the development of a physical model to describe the fundamental mechanisms of the friction. The physical model then serves as the basic structure for the development of a complex model able to capture a wider spectrum of the deterministic and stochastic dynamics of friction. To assess the accuracy of the complex model, two estimation algorithms are formulated to estimate the unknown parameters in the model and to test the model against experimental data. One algorithm is based on the maximum likelihood principle to estimate the constant parameters for stationary friction dynamics, and the other based on the extended Kalman filter to estimate the time-varying parameters for nonstationary friction dynamics. The model and the algorithms are all validated through experiments.
Modeling and Simulate Analysis for Micro-thermoelectric Generator
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
S. Ruiyin and L. Wei and Y. Canjun and L. Yisheng and L. Yonggang and F. Linjian,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 398-402,
April 2005
view abstract
Due to the effect of small scale, Thomson effect, contact source resistance, thermal conduct overlay piece and current conduct layers, etc. have great effect on the output power and efficiency of micro-thermoelectric (micro-TE) generator. Based on these factors, the accurate design model of output power and efficiency were built up. Setting the max power or max power per mass/volume as target function, the parameters of generator such as the length and the number of thermopile were optimized, and the resulting formula were fetched, which provides theoretical guidance for the further step. The performance of the generator was analyzed by experiments.
Modeling and Simulation for Requirement Generation of Heavy Vehicles Steering Gears
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Dell’Amico, Alessandro andPohl, Jochen and Krus, Petter,
2010,
pp. 475-490,
September 2010
view abstract
Today’s passenger vehicles are becoming more and more safe as more steering related active safety functions are being introduced. As an example, lane keeping assist functions or
even electronic vehicle stability with steering intervention can be mentioned. However, the same trend can yet not be witnessed for heavy vehicles, which is, among others, due to a
lesser degree of controllability of the steering system. While electric power assisted steering has been introduced in passenger cars in recent years on a broader basis, electric power assisted steering is yet not suitable for heavy vehicles due to heavier loads on the steering rack.
Heavy vehicles thus lack a freely programmable steering system. The purpose of this paper is to generate and evaluate the requirements of future hydraulic actuation concepts for heavy vehicles, where emphasis is put on the required steering actuator linearity and bandwidth.
Both actuator response and linearity are decisive for transmitting a proper steering feel to the driver. In this study we provide a structured approach to derive the required bandwidth as a function of the system sizing and provide a simulation supported method for deriving the requirements of linearity and accuracy.
Modeling and Simulation of a Fuel metering system, employing a pulse width modulated unloading valve connected to a fixed displacement pump
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
S. Vijayakumar and R. S. Chandran,
2002, Juli 2002
view abstract
The performance of a fixed Displacement Pump connected to an unloading valve located downstream was
studied using modeling and simulation techniques in this paper. The impetus for this investigation was to
convert a fixed displacement pump to a variable delivery pump. This can be achieved by bypassing a
certain amount of the pump output flow to the tank, thus producing variable flow at the load. The unloading
valve was driven by high frequency Pulse Width Modulated (PWM) signals. This situation is akin to
variable flow requirement demanded of a fuel metering system of an automobile. The system was modeled
using the classical bond graph approach. The Fuel Metering System was modeled as a combination of
Compliance, Inertance and Resistance elements. Performance of both Multi point Fuel Injection (MPFI)
and Gasoline Direct Injection (GDI) engines were studied for varying duty cycles of the unloading valve
and the firing frequency of the fuel injectors. The results indicated that the performance of the Fuel
Metering System is closely connected to the ratio between the Pulse Width Modulated duty cycle of the
unloading valve and the firing frequency of the fuel injector. A number of simulations were run to obtain
the operating characteristics over a wide range of operating spectrum. MATLAB/Simulink® was used to
run the simulations using Simulink S-functions.
Modeling and Simulation of a Gas Temperature Control System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
D. Jingmin and Z. Li and F. Xiaoyun and L. Baoren,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 459-462,
April 2005
view abstract
This paper describes a gas temperature control system and presents a self-regulating fuzzy algorithm of PID control. To achieve a signal of the gas temperature with higher degree of accuracy and less response time, both of flux and power of heating are controlled in the algorithm. The impact of system parameters on performance is also analyzed in the paper. The results of simulation indicate the algorithm is reasonable. The work lays the foundation for practical application.
MODELING AND SIMULATION OF AN AXIAL PISTON SWASH PLATE PUMP USING SIMULINK S-FUNCTIONS
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G. K. Seeniraj and R. S. Chandran,
2004,
pp. 531-542,
Juni 2004
view abstract
Hydraulic systems are commonly employed in industrial and mobile applications due to their power density, quick response and reliability. The main component in hydraulic power generation is the pump. For robust applications requiring high operating pressure and flow rate, axial piston swash plate pump is the commonly used variety. Design and development of an axial piston pump is highly complex in nature and involves large amount of testing and verification. Best way to design a complex system such as a pump is to predict its performance using computer simulations before committing to manufacture. In this paper, the development of a mathematical model of a pump and its simulation are presented. The simulation model was developed on a MATLAB/SIMULINK® platform using S-functions. The simulation predicts flow rates into and out of each piston, pressure inside the piston chamber, and resulting flow and pressure ripples. The model was developed to investigate effectiveness and feasibility of various noise reduction techniques and performance analysis.
Modeling and Simulation of Hydraulic Constant Flow Supplied Open Center Servomechanisms
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
L. N. Vasile and N. Vasiliu,
2004,
pp. 579-586,
Juni 2004
view abstract
The paper is devoted to the mathematical modeling and numerical simulation of the hydromechanical constant flow supplied, open center servomechanisms. These force or torque amplifiers are widely used for their low power consumption, due to the permanent supply pressure variation according to the hydraulic motor load, and to their good enough precision too. The big amount of saved energy is the main reason for the wide scale usage of these boosters, as fundamental components of the cars steering systems, copy-milling machines, speed governors, electrohydraulic flow amplifiers and many other technical systems. The practical computation was performed for a classical car steering system taking into account ideal geometry of the rotary flow valve, and small enough car structure compliance. These theoretical results are found in good agreement with the experimental ones.
Modeling and Validation of an In-line Hydraulic Silencer
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
N. E. Earnhart and K. A. Marek and K. A. Cunefare,
2010,
volume 1,
pp. 101-113,
Juni 2010
view abstract
Fluid power is often considered to be noisy. However, it has certain advantages over other energy transport
technologies, one such advantage being higher power density. It is of interest to exploit the advantages of fluid power
and expand it to use in nontraditional applications, which may require that equipment be used in noise-sensitive
environments. This will require a reduction of noise in fluid power systems to increase the appeal of the technology to
potential consumers. This project seeks to passively reduce noise in fluid power through the novel design of a hydraulic
in-line silencer. Theoretical modeling and experimental evaluation of both a prototype hydraulic silencer and a
commercially available model are presented here. The prototype shows 6-10 dB improvement over the commercial
model for apparent transmission loss. Comparison of the experimental data with theoretical modeling is also explored.
Modeling and Verification of an Innovative Active Pneumatic Vibration Isolation System
H. Porumamilla and A. G. Kelkar and J. M. Vogel,
In Journal of Dynamic Systems, Measurement, and Control,
2008,
volume 130,
Mai 2008
view abstract
This paper presents a novel concept in active pneumatic vibration isolation. The novelty in the concept is in utilizing an air-spring-orifice-accumulator combination to vary the natural frequency as well as inject damping into the system per requirement, thereby eliminating the need for a hydraulic cylinder or a magnetorheological damper. This continuously variable natural frequency and damping (CVNFD) technology is aimed at achieving active vibration isolation. For analysis purposes, a particular application in the form of pneumatic seat suspension for off-road vehicles is chosen. A mathematical model representing the system is derived rigorously from inertial dynamics and first principles in thermodynamics. Empirical corelations are also used to include nonlinearities such as friction that cannot be accounted for in the thermodynamic equations. An exhaustive computational study is undertaken to help understand the physics of the system. The computational study clearly depicts the CVNFD capability of the vibration isolation system. An experimental test rig is built to experimentally validate analytical and simulation modeling of the system. Experimental verification corroborated the variable natural frequency and damping characteristic of the system observed through computational simulations.
Modeling a Pneumatic Turbine Speed Control System
Eric R. Upchurch and Hung V. Vu,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 222-225,
März 2000
view abstract
Abstract not available.
Modeling, Experimentation, and Simulation of an Air-Over-Hydraulic Brake System
Xicheng Xiong and Jianhua Wei and and Jian Chen,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
Mai 2009
view abstract
This paper deals with the development and validation of an analytical dynamic model of an air-over-hydraulic (AOH) brake system that is widely used on loaders. The AOH system is broken into five simple and cascaded subsystems, pneumatic circuit, air-hydraulic actuator, brake line, wheel cylinder, and disk brake. Pneumatic, hydraulic, and mechanical dynamics are taken care of in each subsystem. The determination of model coefficients is introduced in detail. Many experiments are performed on an experimental setup of the real AOH system on a loader and the experimental data are compared with the simulation results. Preliminary analysis shows that the simulation results are in good agreement with the experimental data. Other researchers in the areas of brake systems in construction machinery would find the model useful for similar system modeling and analysis
Modeling of Digital-Displacement Pump-Motors and Their Application as Hydraulic Drives for Nonuniform Loads
Md. Ehsan and W. H. S. Rampen and S. H. Salter,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 210-215,
März 2000
view abstract
The digital-displacement pump-motor is a hybrid device, which combines reciprocating hydraulics with micro-processor control, creating a highly integrated machine capable of producing variable flow and power. It is based on the conventional hydraulic piston pump but with actively controlled poppet valves for each cylinder. This allows enabling or disabling on a stroke-by-stroke basis in any desired sequence. Time-domain modeling of the pump-motor system predicts the performance under variable-demand, variable-speed at different control-modes. The advantages of this approach over conventional techniques lie with both the response speed and the inherent energy efficiency.
Modeling of dynamic behaviors of friction
H. Yanada and Y. Sekikawa,
In Mechatronics,
2008,
volume 18,
pp. 330-339,
September 2008
view abstract
This paper deals with modeling of dynamic behaviors of friction in the sliding regime. Using a hydraulic
cylinder, friction characteristics are experimentally investigated under various conditions of velocity variation.
The friction force of the hydraulic cylinder is measured based on the equation of motion using measured values of the pressures in the cylinder chambers and the acceleration of the hydraulic piston. Comparison between measured unsteady-state friction characteristics and those predicted by the LuGre model shows that the LuGre model cannot simulate the real friction characteristics of hydraulic actuatos.
In this paper, the LuGre model is modified taking the dynamics of lubricant film formation into
consideration. The lubricant film dynamics is approximated by a first-order lag element and its time constant
is varied among the acceleration, deceleration and dwell periods. Experiments make clear the dynamic behaviors of the friction of the hydraulic cylinder. It is shown that the modified LuGre model can simulate the real dynamic behaviors of the friction of the hydraulic actuator with a relatively good accuracy.
Modeling on an electro-pneumatic cylinder actuator for nonlinear and adaptive control, with application to clutch actuation in heavy-duty trucks
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
G.-O. Kaasa and P. J. Chapple and B. Lie,
2004,
pp. 255-273,
Juni 2004
view abstract
The paper presents a 6h-order dynamic model of an electro-pneumatic cylinder actuator suited for nonlinear and adaptive control. The model consists of the actuator position, velocity, friction deflection, pressures of both chambers, and the valve spool position as dynamic states. The considered application is an electro-pneumatic clutch actuator controlled by a three-way proportional valve, which is used for clutch actuation in automated manual transmissions on heavy-duty trucks. The pneumatic clutch actuator operates against a clutch compression spring which constitutes the main load of the actuator. The clutch compression spring, which is a diaphragm spring with a highly nonlinear position-load characteristic, is modeled using a parameter-affine parametrization utilizing normalized Gaussian basis functions. The resulting friction force in the cylinder actuator and clutch is modeled using a smoothed version of a simple 1st-order dynamic friction model - known as the LuGre model. The air dynamics of the two pneumatic chambers are modeled using the common reduced-order isothermal model with the pressure as dynamic state. A generalized flow rate equation based on the standardized orifice flow equation is developed for flow rate modeling of pneumatic components in general. This equation is utilized to construct a model of the fixed outlet restriction of the second cylinder chamber. Combined with a parameter-affine parametrization of the nonlinear spool-conductance characteristic using normalized Gaussian basis functions, the generalized flow rate equation is further used to constuct a model of the spool-flow characteristic of the proportional valve. The resulting valve flow model is highly accurate, and suited for nonlinar and adaptive control by a backstepping approach. Furthermore, the dynamics of the electromagnetic valve actuator, i.e., the dynamics from control input to valve spool postion, is modeled by a simple 1st-order linear model.
Modeling, Realization, and Simulation of Thermo-Fluid Systems Using Singularly Perturbed Sliding Manifolds
Brandon W. Gordon and Harry Asada,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 699-707 ,
Dezember 2000
view abstract
A new approach based on sliding control is presented for modeling and simulation of thermo-fluid systems described by differential-algebraic equations (DAEs). The dynamics of thermo-fluid systems are often complicated by momentum interactions that occur on a time scale that is orders of magnitude faster than the time scale of interest. To address this problem the momentum equation is often modeled using algebraic steady state approximations. This will, in general, result in a model described by nonlinear DAEs for which few control methods are currently applicable. In this paper, the modeling problem is addressed using an approach that systematically constructs an explicit state space approximation of the DAEs. The state space model can in turn be used with existing control methods. This procedure, known as realization, is achieved by solving an associated nonlinear control problem by combining boundary layer sliding control with the singular perturbation method. The necessary criteria for key properties such as convergence, stability, and controllability are established. Further, the new approach is illustrated using a vapor compression cycle example. This demonstrates significant advantages over directly modeling momentum interactions.
Modeling the flow phenomena in gerotor pumps
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
P. Antoniak and J. Stryczek,
2004,
pp. 1-8,
Juni 2004
view abstract
The problem of modeling and simulating flow phenomena in gerotor pumps has been presented in the
paper. In order to do that, design and operation principles have been discussed. Additionally, characteristic
gerotor pump zones have been introduced and described. On the basis of that, a general mathematical
model of the flow phenomena has been derived and presented. The model has been completed with
equations that describe internal flows as a function of gearing, kinematics and hydraulic parameters. A
simplified version of the model has been used as the basis of the simulation model. Finally, the simulation
results have been compared to the experimental data and conclusions have been formulated.
Modeling the Pneumatic Subsystem of an S-cam Air Brake System
Shankar C. Subramanian and Swaroop Darbha and K. R. Rajagopal,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 36-46,
März 2004
view abstract
This paper deals with the development of a fault-free model of the pneumatic subsystem of an air brake system that is used in commercial vehicles. Our objective is to use this model in brake control and diagnostic applications. The development of a diagnostic system would be useful in automating enforcement inspections and also in monitoring the condition of the brake system in real-time. This paper presents a detailed description of the development of this model and of the experimental setup used to corroborate this model for various realistic test runs.
Modeling the Vacuum Circuit of a Pneumatic Valve System
J. Galindo and H. Climent and C. Guardiola and J. Doménech,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
Mai 2009
view abstract
The aim of this article is to present the theoretical and experimental work related to the vacuum system used for controlling the actuation of pneumatic valves in internal combustion engines in order to obtain a physical model of this system. In this context, these valves control the turbocharger operation in a two-stage sequential turbocharged diesel engine. With the purpose of providing the model with information, several characterization tests of the elements that integrate the vacuum system were performed. Related to the theoretical contents, two models of the vacuum system were developed and compared, either by using a 1D or a 0D approach. Within the experimental section the obtained instantaneous pressure in the actuator chamber of four air valves and two storage reservoirs of the circuit are measured and compared with the modeling results. Since the simulations show good agreement when comparing the instantaneous pressure evolutions and valve movement with the experimental data, the model can be used to predict the behavior of the vacuum system. Finally, the model is used to optimize the transient turbocharger sequential operation under real engine running conditions. The simulation results predict with accuracy the measurements acquired in an engine test bench. Therefore a consistent methodology has been established in order to reproduce the vacuum system behavior and can be used as a designing tool for complex applications devoted to engine controlling tasks.
Modelling and Control of a Fast Switching Hydraulic Drive
Hydraulics and Pneumatics 2005, Problems and development tendencies in the beginning of the 21st century, Wroclaw, Poland
ISBN: ISBN 83-87982-41-5,
H. Kogler, B. Winkler and R. Scheidl,
Polish Society of Mechanical Engineers and Technicians,
ed. ,
2005,
volume 1,
pp. 459 - 464,
Mai 2005
view abstract
This paper reports about an application of a recently developed fast hydraulic switching valve, namely the control of a linear drive. The valves are operated in a pulse-width mode to achieve a quasi proportional flow control. The modelling, simulation, and control aspects are treated.
The hydraulic drive actuates a dead load that should be positioned vertically via a hydraulic cylinder. The annulus chamber is connected to a constant supply pressure and the piston side can be connected either to supply or to tank pressure via two 2/2 way switching valves. The mathematical model of the hydraulic switching system should also be a good basis for the controller design.
The aim of the drive is to position the load. Basically, this could be realised with an ordinary P-controller, but a better performance and accuracy is achieved by feed-forward control. To calculate the control law with well established theories a representative continuous model is necessary. Such a model is created by averaging the equations of the different switching states.
Following a flatness based feed-forward control can be developed. Due to uncertain parameters, however, the feedforward control in combination with a feed-back PD-controller leads to the desired accuracy.
Modelling and control of a free liquid-piston engine compressor
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
C. Yong and E. Barth and J. Riofrío,
2008,
pp. 245-257,
September 2008
view abstract
This paper presents the modeling and control of a prototype compact free liquid-piston engine compressor. The dynamic model includes 1) the injection dynamics of the air/fuel mixture, 2) the dynamics of heat release during combustion, 3) the inertial dynamics of the magnetically latched combustion valve, 4) the mass flow dynamics of the combustion and exhaust valves, 5) the inertial dynamics of the free piston, and 6) the compression and pumping dynamics. The model is then utilized to design an iterative control scheme to control the amount of fuel injected for each cycle, the timing of the spark, and the timing and duration of the exhaust valve. Simulation results show a good correlation with experimentally obtained data, and simulated closed-loop control of the engine is demonstrated.
Modelling and Control of a High Speed Hydrostatic Transmission
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
I. A. Njabeleke and R. F. Pannett and P. K. Chawdhry and C. R. Burrows,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 1-10,
November 1998
view abstract
Fluid power systems are highly nonlinear, making the application of traditional linear feedback control techniques challenging. H∞ robust control techniques have been extensively studied recently but their practical feasibility in fluid power systems has not been convincingly demonstrated. In this paper, we consider the modelling
and application of H∞ robust control to a hydrostatic transmission. We propose a dual mode controller which is extremely effective, delivering robust stability over the entire speed range and offering bumpless transfer, windup protection and multirate sampling at no extra cost, a factor which is crucial in digital implementation. The
particular H∞ approach used is McFarlane and Glover's loop shaping which, in addition to simplicity, admits a wider class of uncertainties than comparable schemes. We show that despite some challenges, H∞ loop shaping is able to satisfy a variety of control objectives and a successful application need not be of high order.
Modelling and Control of Hydraulically Driven Parallel Redundant Manipulator
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
Y. Liu and H. Handroos,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 95-110,
November 2003
view abstract
MULTIPOD is a robotic manipulator based on two parallel 3-DOF mechanisms in serial connection. It is actuated by six hydraulic servocylinders and it has six degrees of mobility. The pose of end effector is described by the five degrees of freedom due to the structure of the manipulator. For the purpose of control and real time application, the inverse kinematic, dynamic and control performance analysis are carried out. Some preliminary results are given to demonstrate the performance of manipulator.
Modelling and control of marine engineering systems
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
T. Heeringa,
2006,
pp. 225-249,
September 2006
view abstract
The traditional modeling approach in engineering is mathematical, but thanks to the advances in computer technology it is now possible for the practical engineer to model systems in a more “user friendly” way.
This paper will demonstrates the power and simplicity of Bond Graphs in modeling systems. Bond Graph modeling was originally developed in the late 1950s by the late Prof. Henry M. Paynter of M.I.T. Prof. Paynter acted well before his time as the main advantage of his creation, other than the modeling insight that it provides and the ability of effectively dealing with mechatronics, came into fruition only with the recent advent of modern computer technology and the tools derived as a result of it, including symbolic manipulation, MATLAB and SIMULINK and the simulation package 20-sim which allows direct input of the Bond Graph.
To avoid destructive torsional vibrations is of major importance in marine power train design. During transient loads extreme conditions have been observed and efficient methods and tools to analyze such cases are of primary interest to the industry. The system to investigate is a dredge pump drive train in a hopper dredger. The Bond Graph model will include a lumped mass model of the diesel with a simple model of the speed governor, the clutch and the hydraulic controlled gearbox. After the modeling the control of non linear systems with non linear controllers will be discussed.
MODELLING AND CONTROL OF PNEUMATIC VANE MOTORS
P. Beater,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 7-16,
März 2004
view abstract
There is a broad area of applications where pneumatic vane motors offer unique advantages: high power-to-weight
ratio, indifference to overload and stall, cool operation, indifference to dirty or explosive atmospheres. Typically, they
are chosen from manufacturers’ diagrams such that the torque needed is provided by the motor at the required speed. If
necessary, a nozzle is used to reduce speed. Some guidelines have been published about how to design these motors and
how to use them in a position control loop, e.g. for robotic applications. This study derives a mathematical model suited
to time-domain simulation of the motor, both in an open-loop or closed-loop system. Using geometrical data and the
theory of thermodynamic processes the model of an ideal motor is given. In a second step leakage paths and friction are
added to describe the behaviour of real motors. This model is implemented in the modelling language Modelica with
the help of the domain library PneuLib and used to estimate values for the conductance of the nozzles or the friction
terms. Comparisons between the model and measurements are given, both for open-loop and closed-loop operation.
Modelling and Control of Swash-Plate Dynamics
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
J. Petrić and V. Ivanović and M. Kostelac,
2008,
pp. 112-119,
September 2008
view abstract
There are many new examples of applications of hydrostatic transmissions in the mobile scope. Beside the efficiency, the control ability and the fast response of the hydrostatic transmission are very important in modern applications. In this regard, a DC servomotor can be applied as an actuator of the variable displacement mechanism of smaller hydrostatic units. In this way, fast responses and favorable control ability can be accomplished. This paper considers a DC servo-motor as the actuator for the variable displacement mechanism of the pump.
Background of modeling of the torques acting on the swash-plate is given in the paper, as well as the DC-based control consideration. The experimental setup with the hydrostatic transmission, and DC servo-motor as an swash-plate actuator is described. The cascade structure of the DC servo-motor control is explained and discussed in the paper. The experimental results of swash-plate control are given, too.
Modelling and Control Strategies and Applications for Alternating-flow Hydraulic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Chengu and Z. Jingyi and W. Wei,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 228-233,
April 2005
view abstract
Alternating-flow hydraulic (AFH) system is a new type of hydraulic system, and AFH technique was first used in military field in 1920s, civilian industry in 1960s. However, it differs from the traditional direct-flow hydraulic (DFH) system in operation mechanism, modelling methods, control strategies and applications, as well as some peculiarities. AFH system transfers signals and energy by piping or pulsation of actuating medium in tubes, especially suit for source of vibration. Although there is some commonness of the two, nothing but modelling, control strategies and applications is to be discussed in the article.
The mathematical model (transfer function, differential equation, etc.) can be determined theoretically from first principles. There are some common methods, such as bond graph method, hydraulic resistance networks theory, subsystem coupling method etc. However, a difficulty remains, namely, how to find the parameters or to get precise mathematical model in consequence of the typical unknown and uncertain nonlinearity of AFH system. For DFH system, there are standard test procedures for determining these parameters. But for AFH system, these techniques don't work as well. Therefore, we often have to resort to more generic experimental methods for determining the parameters of mathematical model.
In recent years, electro-hydraulic servo system has been applied to AFH system. This type of AFH system is superior to traditional cam-type driven one. However, electro-hydraulic servo system PID control method can't meet the increasing request of control quality. Although precise mathematical model can be set up in some cases, it is always so complex that makes the analysis, design and practice of the traditional control method based on the model more difficult. The intelligent control based on knowledge and not reliant to the precise mathematical model gives new ideas for solving these problems. Fuzzy control and neural network control are two kinds of artificial intelligent control methods. Integration of fuzzy control, neural network control and traditional PID control for AFH electro-hydraulic servo system is discussed in the Paper.
Owing to its limited applications and some undesired disadvantages such as low efficiency and strong noise, AFH technique advances heavily in the past decades. AFH components and Systems and their application domains are introduced at the end of the article. The present research status and potential applications in the future of the AFH technique are expected.
Modelling and Dynamics Simulation of Pneumatic Systems by Means of RHD Resistances (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
L. Dvořák and J. Kopáček,
2008,
pp. 286-293,
September 2008
view abstract
This paper deals with mathematical modelling of pneumatic systems by means of RHD resistances, which are resistance to motion R, resistance to acceleration H and deformation resistance D. Each of pneumatic elements can be described as a one type of resistance or more often as their combination. This method is used with the good results in the field of hydraulic systems however in the area of pneumatic systems is not commonly used. The reason is in properties of the compressed air which make calculations difficult.
The paper contains the relations for calculation of particular resistances and the composition of basic elements models, i.e. directional control valve, compressed-air pipelines and double-acting cylinder. Directional control valve can be described as a resistance to motion R. Resistance is caused by restriction when air flows through the valve. Quantities of resistances can be calculated from flow coefficient Kv and also depend on the pressure ratio, equation (1). Pneumatic cylinder can be described as a combination of all resistance types. Resistance to motion R is caused by friction of piston and piston rod and its quantity can be calculated from efficiency of cylinder. Resistance to acceleration H is caused by inertia of piston and piston rod mass and moving mass connected with piston rod. Deformation resistance D is caused by air compressibility. Operation of pneumatic cylinder can be distributed to three time parts. The first part concerns fulfilment of dead volume. During the first part the pressure can be calculate from equation (9). Second part, i.e. movement of piston, can be described by equations (11) to (15). Pressure during third part when the movement is finished can be calculated from equation (17) and pressure in the exhausted chamber from equation (18) during all time parts. Mathematical model of the whole mechanism is compiled from models of single elements.
On the base of mathematical models of pneumatic elements the user friendly program in the software Matlab – Simulink was created. For the simulation of dynamic characteristics it is necessary to put into the program the parameters of elements for example the diameter of the piston and piston rod, the stroke of piston, pipeline dimensions, the flow coefficient of directional control valve and also the supply pressure. The results of the simulation are curves of piston position, velocity and the pressures in cylinder chambers vs. time. The model provides good results for the double-acting cylinders with the piston diameter up to Dp = 63 mm and with stroke up to h = 500 mm and where the directional control valve with flow coefficient up to Kv = 0,108 m3.h-1 was used.
Modelling and measurement of the compliance and friction losses of screwjack electromechanical actuators
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
W. Karam and J.-C. Mare,
2007,
pp. 145-157,
September 2007
view abstract
In this communication, the behaviour of a roller screw electromechanical actuator (EMA) is studied around the null velocity in order to provide accurate models for force control applications, typically dynamic load generators for aerospace test benches. The first part is dedicated to the power needs and the test bench design with special consideration to architecture and stiffness. In the second part, an upgraded nut-screw model is proposed in accordance with experimental results. Measurement processes are discussed in detail, covering parameters identification and data filtering, while applied to mechanical losses and compliance variation due to preload. This work is performed in a non intrusive way (external view) so that it can be applied by systems integrators without disassembling the EMA.
Modelling and Optimization in Pressurized-Air Networks – A first Approach with Respect to Energy-Efficiency
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
S. V. Krichel and O. Sawodny,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 317-328,
März 2010
view abstract
Compressed air is a basic energy source in several industrial areas. The energy of relaxing air is used during manufacturing processes, commonly as driving force for actuating pneumatic cylinders and in power tools such as pneumatic screwdrivers. The widespread use of pneumatic air justifies efforts to reduce losses within the compressed-air infrastructure. The two main loss sources are (1) the consumption of electrical energy for the production of pressurized air with compressors of different kinds and sizes and (2) the distribution through piping networks with non-negligible leakage effects and pressure drops. In order to reduce losses and optimize the generation and transport of compressed air, model-based approaches are used. The paper focuses on two topics: first, a dynamical model of a rotary oil-flooded screw compressor is shown and validated with measurements. Second, the modelling of pressurized-air networks with respect to transmission line modelling, modelling software and choice of abstraction level is briefly introduced.
MODELLING AND SIMULATING HYDRAULICALLY BALANCED EXTERNAL GEAR PUMPS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
F. Paltrinieri and M. Milani and M. Borghi,
2002, Juli 2002
view abstract
The paper presents some developments of a research activity regarding hydraulically balanced external gear pumps.
Numerical models are introduced in order to study gears radial equilibrium and axial bearing blocks balance. A numerical
approach useful for determining the eccentric positions assumed by gears inside the pump casing and to assess the radial
thrusts acting on gears is proposed. The effect of the running in process on the casing internal surface and on the pressure
distribution in sealed spaces between teeth is also shown and discussed. At the end a numerical model useful in designing
bearing blocks balancing surfaces is outlined. Comparisons of numerical and experimental results seem to encourage the
development of the study.
Modelling and Simulating of Jam Fault in Electro-hydraulic Proportional Valve Based on System View Software
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Li Weibo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 646-649,
April 2005
view abstract
Through the analysis of the inner magnetic dynamic process of electro-hydraulic proportional valve, this paper presents the sensorless detecting method based on "electro-reflection" to feed back the fault information directly. And the paper places emphasis on the study of typical inner characteristic parameter of electro-hydraulic slide valve influence on the detecting sensitivity and robustness. On the basis of research of theoretical model building for jam fault, the oscillation current waveform and frequency influence on the non-sensor detecting sensitivity and robustness was analyzed by simulation software SystemView. Simulation results demonstrate that oscillation current with sinusoid waveform and 50Hz frequency has a best performance in this sensorless detecting method.
MODELLING AND SIMULATION OF EXTERNAL GEAR PUMPS AND MOTORS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
B. Zardin and M. Borghi,
2008,
pp. 323-341,
Juli 2008
view abstract
In this paper a lumped parameter model for the numerical simulation of the dynamic behaviour of external gear
pumps and motors is presented. The model is developed in AMESim® environment, combining the use of
AMESim® libraries of components and a self-made library developed in C++ code. The choice of a single
modelling environment allows both the simulation of the machine dynamic behaviour and the analysis of the
interaction between the external gear unit itself and the hydraulic circuit in which it is working.
Particular attention is devoted in the model in order to consider the eccentric position of the gears inside the
casing. Moreover, the relevance of an accurate definitions of the flow leakages involving the inter-teeth
volumes, considering also the Couette flow contribution, is highlighted. Finally, a numerical analysis has been
carried out by means of the model in order to determine the influence of load and rotational speed on the
dynamic behaviour of the machine; results about the pressure ripple, flow rate at the outlet port, pressure
transients on the inter-teeth volumes and gears position inside the casing are exposed and commented.
MODELLING AND SIMULATION OF INTEGRATED HYDRAULIC PROPULSION SHIP
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
J. Yulong and S. Yuqing and C. Lei and Z. Yindong,
2006, August 2006
view abstract
As the development of ships tends towards high-speed, large-scale and high-power, every ship propulsion method
has its own limitations. In this paper, a new ship propulsion method, Integrated Hydraulic Propulsion (IHP), was put
forward to solve the problem. Then further research work was done on the principle of IHP method and the advantages
and disadvantages of IHP method were discussed. At the same time, a dynamic mathematical model of an IHP ship was
developed on the basis of previous work. The process of modelling was given. With the simplified dynamic model, a
simulation study was done through the software Matlab/Simulink. The simulation result proves that not only is the IHP
way feasible, but also it can be used widely for its own characteristics for certain ships which are subjected to highly
varying working conditions and high-power. To a certain extent, the problem mentioned before can be solved. This
new method diversifys the existing ship porpulsion methods.
Modelling and Simulation of Mobile Hydraulic Crane with Telescopic Arm
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
B. Nielsen and H. C. Pedersen,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 433-446,
November 2003
view abstract
For loader crane applications resolved motion control is assumed to be one of the areas for
development in the future. To develop and evaluate different control strategies for a resolved
motion control system, information about the dynamic behaviour of these cranes is necessary.
In the current paper a model of a loader crane with a flexible telescopic arm is presented, which
may be used for evaluating control strategies. The telescopic arm is operated by four actuators
connected hydraulically by a parallel circuit. The operating sequences of the individual
actuators is therefore not controllable, but depends on the flow from the common control valve,
flow resistances between the actuators and friction. The presented model incorporates structural
flexibility of the telescopic arm and is capable of describing the dynamic behaviour of both the
hydraulic and the mechanical system, including the relative movement of the individual mechanical
bodies in the telescopic arm. The model is verified through comparisons between
simulated and measured results for various operating conditions.
Modelling and Simulation of the Bearing System for Sealless Pneumatic Cylinders
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
D.-S. Kim and H.-S. Seo,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 245-253,
November 2003
view abstract
General pneumatic cylinders are provided sliding seals which seal the elements one to another
in relative motion. These seals, subjected to thermal shock, can be damaged and stiffened in
such a manner that compromised the cylinder working irreparably. This inconvenience may
be overcome by elimination of the seals and by using cylinders realized with minimum
clearances. The pneumatic cylinder without seals is practically free from the well-known
stick-slip phenomenon. In the cylinder of this type, analysis of the bearing is very important.
The optimal design of the bearing has been made by computer simulation.
Modelling and Simulation of the Elasto-Hydrodynamic Behavior of Sealing Gaps
B. Winkler and G. Mikota and R. Scheidl and B. Manhartsgruber,
In Australian Journal of Mechanical Engineering (formerly Transaction of Mechanical Engineering),
2005,
volume 2,
view abstract
Sealing gaps are the predominant way to obturate high pressure from low pressure areas in many hydraulic devices, like valves, pumps, etc. In many cases, the elastic deformation of the components forming the gap is minor and can be disregarded. But if very high pressures, small nominal gaps, or flexible components are involved, the elastic deformations may strongly couple with the pressure distribution of the creeping flow in the gap. We will present a method for the efficient treatment of this highly non-linear elasto-hydrodynamic problem. The elastic deformations of the solid bodies are described by an influence matrix, which gives the displacement field as a function of a unit force (or pressure respectively) at a certain (nodal) point. This matrix may easily be computed by a Finite Element program. The coupled problem is treated by numerically solving the Reynolds Equation of the creeping flow - discretized by a Finite Difference method - and the coupled deformation problem. Rigid body motions are considered as well. The highly non-linear influence of the gap distribution, may cause severe numerical troubles unless special methods are applied to cope with this problem. We show the performance of this method by an example.
MODELLING AND SIMULATION UTILIZED IN RESEARCH AND DEVELOPMENT OF MOBILE HYDRAULICS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
T.. J. Käppi,
2000,
pp. 353-361,
September 2000
view abstract
Mobile hydraulics include fluid power components and systems utilized in mobile machinery such as forest
machines, excavators and hydraulic lifts. It has special features compared to the stationary i.e. industrial
hydraulics. This paper gives an overview of mobile hydraulics and presents the benefits that can be achieved by
employing modelling and simulation in order to carry out R&D of such machines.
Modelling a Variable Displacement Axial Piston Pump in a Multibody Simulation Environment
Alessandro Roccatello and Salvatore Mancò and Nicola Nervegna,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 456-468,
Juli 2007
view abstract
Analysis of a variable displacement axial piston pump, as in other complex fluid power and mechanical systems, requires appropriate insight into three multidisciplinary domains, i.e., hydraulics, mechanics and tribology. In recent years, at FPRL, modelling of axial piston pumps has evolved in AMESim (one-dimensional code) where a three-dimensional mechanical approach has required generation of proprietary libraries leading to the evaluation of internal forces/reactions in all pump subsystems. Tribologic aspects in axial piston pumps modelling are also being investigated but AMESim, in this respect, does not appear as the appropriate computational environment. Consequently, a new approach has been initiated grounded on MSC.ADAMS. In this perspective, the paper details how the model has been developed through proprietary macros that automatically originate all pump subsystems parametrically and further apply required constraints and forces (springs, contacts and pressure forces). The ADAMS environment has also been selected due to co-simulation capabilities with AMESim. Accordingly, the paper elucidates how the entire modelling has been construed where hydraulics is managed in AMESim while ADAMS takes care of mechanics. A comparison between simulated and experimental steady-state characteristics of the axial pump is also presented. As such this paper indicates an innovative methodology for the analysis of complex fluid power systems in the hope that, eventually, tribology will also fit into the scene.
MODELLING FILTRATION IN WATER HYDRAULIC SYSTEM
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
H. Riipinen and S. Varjus and S. Soini and J. Puhakka and K.T. Koskinen and M. Vilenius,
2002, Juli 2002
view abstract
Filtration in water hydraulic system may be problematic, due to biological and physical contamination. This contamination
may cause very quick increase in pressure difference over the filter element. Modelling filtration in water
hydraulic system is needed for prediction of the lifetime of the filter element. The principle, how the filtration model
has to build is shown in this paper.
Modelling of an automated manual transmission system
G. Lucente and M. Montanari and C. Rossi,
In Mechatronics,
2007,
volume 17,
pp. 73-91,
view abstract
Vehicles with automated manual transmissions (AMT) for gear shift control offer many advantages in terms of reduction of fuel consumption and improvement of driving comfort and shifting quality. Complexity, nonlinearity and high-order dynamics of the automated driveline, combined with strict requirements for high performance gear shifts, demand the development of driveline models, which include a detailed description of the actuators. These models can be useful for different purposes: during system development, to evaluate the achievable performance and its dependency on system properties; as simulation tools for gear shift control algorithm design. In this paper, physically-based detailed nonlinear models of the electro-hydraulic actuated gearbox and of the dry clutch electro-hydraulic actuator of an automated manual transmission are developed. In order to analyze their behaviour and their impact on the drivetrain during gear shifts, actuator models are integrated with a simplified transmission shafts dynamics. A reduced-order model of the gearbox actuator, which is valid when dither signal is imposed to servovalves, is developed with the aim of analyzing its properties and performances.
Model parameter identification has been performed mostly by means of theoretical relations and design data. Experimental tests, performed on a commercial car, confirm that the proposed model is able to describe the actuators behavior and the phenomena characterizing system dynamics during gear shift.
Modelling of a Switching Control Hydraulic System
B. Manhartsgruber and G. Mikota and R. Scheidl,
In Mathematical and Computer Modelling of Dynamical Systems,
2005,
volume 11,
pp. 329-344,
view abstract
Modelling of a hydraulic system featuring a specific type of switching control is presented. Despite conventional hydraulic drive technology where rather smooth changes of pressure and flow rate are intended and where oscillations constitute undesired phenomena, switching control provokes oscillations as an indispensable element to achieve high energetic efficiency with valve control. The system under study is one which comprises a novel switching valve, a long line with considerable wave propagation dynamics, a hydraulic cylinder, and the valve's dynamics.
Modelling of a Water Hydraulic Poppet Valve Using CFD Technique
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
T. Leino and M. Linjama and K.T. Koskinen and M. Vilenius,
2002, Juli 2002
view abstract
In a design process of a new hydraulic valve, without a very strong experience, much time has to be used to get
to a good product. The exact final result can usually not be seen before the first prototype is manufactured. The
CFD method is a useful tool for understanding the flow field inside the valve to be designed. In this study, the CFD
software is used to model a water hydraulic poppet valve. The main interest has been the cavitation phenomena,
which is a common problem in water hydraulic valves. The results got from the CFD calculations are compared
with the measured data of experimental tests.
The comparison of the calculated and experimental results shows that in this case the CFD method already
gives a good view to the real flow field even if, for instance, the definition of the mesh and the solver parameters
are still requiring more attention. The calculated and measured flow rates through the valve are equal with a good
accuracy and the location of cavitation bubble appearance matches well with the calculated pressure distribution.
MODELLING OF BENT AXIS AXIAL PISTON MACHINES – NEW APPROACH
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
D. Dyminski,
2008,
pp. 451-451,
Juli 2008
view abstract
The prediction of pump and motor performance for a given design of bent axis axial piston machine requires a simulation
model that describes the flow of a compressible and viscous fluid from the ports through the valve plate to the displacement
chamber. It must further consider the gap flow through the lubricating gaps that seal the displacement chamber. The
change of pressure in the displacement chamber resulting from the basic working process of the displacement machine
causes fluctuating forces and moments leading to oscillating micro motion of moveable parts of the rotating group. The
model is based on a non-isothermal gap flow considering the change of gap heights due to micro motion of parts and due to
surface deformations for the connected gaps of a bent axis axial piston machines. One of the major challenges has been the
development of a model of the piston – piston rings – cylinder block interface. The developed model of the rotating group
allows the calculation of real flow ripples at both ports, further the calculation of the instantaneous cylinder pressure, the
internal and external volumetric losses, viscous friction forces, gap heights, oscillating forces and moments exerted on the
machine parts. Implemented models consider the time dependent change of gap heights due to oscillating forces, the
interaction between machine parts, the dependency on design and operating parameters, and the consideration of elastohydrodynamic
effects due to surface deformation of parts forming the gaps. The mathematical description of the fluid flow
from the ports to the displacement chamber and through the sealing and bearing gaps leads to a system of partial and
ordinary differential equations. A new numerical method based on iterative coupling of separate solvers for fluid/solid
domains has been developed to solve this transient nonlinear system consisting of the Reynolds equation and the energy
equation for fluid domain, the equation of elasticity for the solid domain and the determination of gap heights by solving the motion equation of the multi-body system of the rotating group. The initial-boundary conditions such as instantaneous
cylinder pressure are obtained by solving the fluid flow from displacement chamber to the ports.
MODELLING OF HYDRAULIC PIPELINE PRESSURE TRANSIENTS WITH CAVITATION AND GAS BUBBLES
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
J. Dan and L. Songjing,
2006,
volume 1,
pp. 247-254,
Juni 2006
view abstract
In order to predict the pressure transients inside hydraulic pipeline with cavitation and gas bubbles, a mathematical
model and Matlab Simulink simulation method are studied in this paper. The mathematical model is based on the two
equations of motion and continuity. The model of cavitation and gas bubbles’ growing and collapsing is built to
calculate the volume of cavitation and gas bubbles. The model of friction is given as a part of the mathematical model. The
time constants of gas releasing and resolving are estimated. A simulation model, using finite difference method and
Matlab Simulink platform, is developed to handle the prediction. An example of hydraulic pipeline with a valve at one end and a reservoir at the other end is studied. The fluid transients with cavitation and gas bubbles inside the pipeline
are calculated and tested after the valve is closed rapidly. Simulation and experimental results are given. Comparison
of the results shows that, for a certain example pipeline, the mathematical model and simulation method in this paper
can handle the prediction of fluid transients inside hydraulic pipeline with cavitation and gas bubbles.
Modelling of hydraulics and mechanics of a mobile machine
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
A. Vuohijoki and M. Hyvönen and K. Huhtala and M. Vilenius,
2008,
pp. 105-118,
September 2008
view abstract
The effects of the control system flaws in a mobile machine are difficult, and even dangerous, to identify. The use of simulation offers a safe way to find these flaws. In this paper the behaviour of a small mobile machine, has been analysed in two driving situations. The analysis was based on the verified simulation model.
Analysis revealed few problems. Five simple improvements were proposed to correct problems. These proposals were simulated and analysed. Also distributed restriction edge control was tested and the preliminary results were promising.
Modelling of Mechatronic Systems by Symbolic Computation
Proceedings of the 1995 EUROSIM Conference
K. Schlacher and R. Scheidl,
North Holland Verlag,
ed. Breitenecker and Husinsky,
1995,
pp. 657-662,
September 1995
view abstract
A system for the automatic derivation of the state equations of mechatronic systems must be able to handle mechanical systems, electric machines as well as circuits of electrical and hydraulic networks. Variational principles offer a straigthforward approach for computer algebra based methods, where the Lagrangian principle is used for the mechanical and hydraulic components and Tellgen's theorem for the modeling of Kirchhoff networks. Graph theoretic concepts provide a means for determining coordinates of the configuration space symbolically. Hydraulic experiments show, that even a finite state approach for some spatially problems gives good results.
MODELLING OF ORIFICE FLOW RATE AT VERY SMALL OPENINGS
D. Wu and R. Burton and G. Schoenau and D. Bitner,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 31-39,
April 2003
view abstract
Modelling hydraulic control systems that contain flow modulation valves is highly influenced by the accuracy of the
equation describing flow through an orifice. Classically, the basic orifice flow equation is expressed as the product of
cross-sectional area, the square root of the pressure drop across the orifice and a “flow discharge coefficient”, which is
often assumed constant. However, at small Reynolds numbers (such the case of valve pilot stage orifices), the discharge
coefficient of the flow equation is not constant. Further, the relationship between the flow cross-sectional area and the
orifice opening are extremely complex due to clearances, chamfers, and other factors as a result of machining limitations.
In this work, a novel modification to the flow cross-sectional area is introduced and the resulting closed form of
the flow equation is presented. As a secondary benefit, an analytical form of the orifice flow gain and flow pressure
coefficient can be obtained. This closed form equation greatly facilitates the transient and steady state analysis of low
flow regions at small or null point operating regions of spool valve.
MODELLING OF SPOOL POSITION FEEDBACK SERVOVALVES
D. Gordić and M. Babić and N. Jovičić,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 37-50,
März 2004
view abstract
Based on a critical review of the previous research and the comprehensive theoretical analysis of all functional parts
of two-stage electrohydraulic servovalves with a spool position feedback (a current amplifier, a torque motor, the first
and the second stage of hydraulic amplification) a detailed mathematical model of the servovalves was created. The
analysis was based on the fundamental laws of electromagnetism, fluid mechanics and general mechanics. The model
parameters are physical quantities and the complexity of the model is only limited by the possibility of the correct
numerical integration. It includes phenomena and quantities that are of influence on the behaviour of the servovalves,
so it can predict their function in a wide range of expected working regimes. Results obtained with the numerical
modelling on a personal computer were compared with the appropriate experimental data and the validity of the
proposed model was confirmed with satisfactory accuracy.
Modelling of Strongly Pulsating Fluid-Flow in Pipelines of Hydraulic Drives
Proceedings 13th IASTED International Conference on Modelling, Identification and Control, Grindelwald, 21-23 Feb. 1994
ISBN: 0-88986-183-8,
R. Scheidl and D. Schindler,
IASTED,
ed. M. H. Hamza,
1994,
pp. 181-183,
Februar 1994
view abstract
Mormally, flow in hydraulic drive systems is intended to be as smooth as possible, but pulsations cannot be avoided if fast switching of valves does occur. Usually, only the evolution of the pressure in the corresponding hydraulic system is considered and not the flow rate. Precise computation of the latter turns out to be more difficult because of the strange nature of friction in the pipes if rapid changes of flow in combination with laminar turbulenct transition do arise. Usual pipe-friction laws for stationary flow are no more valid and have to be replaced by an advanced model. In this paper flow in pipelines is modelled by spatially one dimensional Finite Elements. Friction shear stress is goverend by an internal state differential equation which yields the values for stationary flow as limit value in the stationary case. The coefficients for this equation are determined by experiments. In a comparison of experiments and computations it is shown that this friction model gives better results for higher frequnecies than a purely quasi-static friction law.
Modelling pipeline dynamics using optimized finite element model
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
K. Sanada,
2008,
pp. 91-104,
September 2008
view abstract
An optimized finite element model of pipeline dynamics has been proposed by the authors. The model is based on a non-uniform interlacing grid system. The grid spacing is optimized to make natural frequencies of the model as close as possible to theoretical ones for extreme boundary conditions. Adjusting the non-uniform grid spacing, the model can be optimized to minimize errors in natural frequencies. Finite element approximation of the equation of motion and the continuity equation leads to a set of ordinary differential equations. It can be represented in state space form. The state-variable vector consists of state variables representing pressure and flow rate at the grid points. The model can be used in adaptive time step integrators, such as Simulink. In this paper, experimental verification of the optimized finite element model is focused. The model is applied to simulation of fluid transients in a test rig made of a stainless-steel pipe having 10 mm in diameter and 36 m in length. The working fluid is water. Fluid transients are caused by quick valve operation. Finally, the optimized finite element model is applied to modelling of a fuel injection valve used for gasoline direct injection systems.
Modelling, Simulation and Experimental Studies on a Variable Displacement Radial Piston Pump Prototype for Automotive Applications
Fluid Power Systems and Technology 1996 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815342,
R. Caretto and S. Mancò and N. Nervegna and M. Rundo,
ASME,
ed. S. S. Nair and R. S. Chandran,
1996,
volume 3,
pp. 1-9,
November 1996
view abstract
Aim of the present study is the development of the mathematical model, the time domain simulation and preliminary experimental analyses of a radial piston pump envisaged for low pressure automotive applications. The pump is a prototype under test at the Fluid Power Laboratory, Dipartimento di Energetica, Politecnico di Torino.
Modelling, simulation and identification of the electro-hydraulic speed governors for Kaplan turbines by AMESim
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
N. Vasiliu and C. Calinoui and D. Vasiliu,
2007,
pp. 189-200,
September 2007
view abstract
The paper contains a report on using AMESim to design and tune a patented type of electrohydraulic digital speed governor for KAPLAN hydraulic turbines. Modeling, simulation and experimental identification are shortly presented. The governor contains two connected position loops included in a speed loop or a power loop. The fine-tuning of the electro hydraulic servo systems by AMESim saved time and gets the possibility of a deeper investigation of the main design parameters influence. The actual performance of the prototype (time response, accuracy, static drop, dynamic drop etc.) was found in good agreement with the theoretical prediction, and CEI demands.
Modelling, simulation and identification of the electro-hydraulic speed governors for Kaplan turbines by AMESim
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
N. Vasiliu and C. Calinoui and D. Vasiliu,
2007,
pp. 189-200,
September 2007
view abstract
The paper contains a report on using AMESim to design and tune a patented type of electrohydraulic digital speed governor for KAPLAN hydraulic turbines. Modeling, simulation and experimental identification are shortly presented. The governor contains two connected position loops included in a speed loop or a power loop. The fine-tuning of the electro hydraulic servo systems by AMESim saved time and gets the possibility of a deeper investigation of the main design parameters influence. The actual performance of the prototype (time response, accuracy, static drop, dynamic drop etc.) was found in good agreement with the theoretical prediction, and CEI demands.
MODEL ORIENTED CONDITION MONITORING OF HYDROSTATIC TRANSMISSION
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
H. Rusanen and J. Rinkinen,
2004,
pp. 489-499,
Juni 2004
view abstract
Reliability is an appreciated characteristic of modern mobile machines. Detecting faults as soon as
possible in their early stages would provide means for preventing severe damages to occur. The paper is
concerned with model based condition monitoring of hydrostatic transmission. A simulation model
together with measured signals is used for monitoring the welfare of the machine.
The most vulnerable components of the hydrostatic transmission are determined with the aid of failure
mode, effects and criticality analysis (FMECA). The FMECA analysis form is tailored to suit especially
for the condition monitoring purposes.
The studied hydraulic system is described and the simulation model of the hydrostatic transmission is
presented. The model is validated against measurement data. Finally, the developed simulation model is
used for simulating malfunction effects to the system.
The results so far are quite promising and at this phase it seems that it is possible to build up condition
monitoring system that can recognize failures from measurement data.
Model Predictive Control of a Fuel Injection System with a Radial Basis Function Network Observer
Chris Manzie and Marimuthu Palaniswami and Daniel Ralph and Harry Watson and Xiao Yi,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 648-658,
Dezember 2002
view abstract
This paper proposes a new Model Predictive Control scheme incorporating a Radial Basis Function Network Observer for the fuel injection problem. Two new contributions are presented here. First a Radial Basis Function Network is used as an observer for the air system. This allows for gradual adaptation of the observer, ensuring the control scheme is capable of maintaining good performance under changing engine conditions brought about by engine wear, variations between individual engines, and other similar factors. The other major contribution is the use of model predictive control algorithms to compensate for the fuel pooling effect on the intake manifold walls. Two model predictive control algorithms are presented which enforce input, and input and state constraints. In this way stability under the constraints is guaranteed. A comparison between the two constrained MPC algorithms is qualitatively presented, and conclusions are drawn about the necessity of constraints for the fuel injection problem. Simulation results are presented that demonstrate the effectiveness of the control scheme, and the proposed control approach is validated on a four-cylinder spark ignition engine.
Model Predictive Energy Management of a Hybrid Hydraulic Vehicle
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
T. O. Deppen and A. G. Alleyne and K. A. Stelson and J. J. Meyer,
2010,
volume 1,
pp. 35-45,
Juni 2010
view abstract
In this paper, a model predictive control (MPC) approach is presented for solving the energy management problem in a
parallel hydraulic hybrid vehicle. The hydraulic hybrid vehicle uses variable displacement pump/motors to transfer
energy between the mechanical and hydraulic domains and a high pressure accumulator for energy storage. A model of
the parallel hydraulic hybrid powertrain is presented which utilizes the Simscape/Simhydraulics toolboxes of Matlab.
These toolboxes allow for a concise description of the relevant powertrain dynamics. The proposed MPC regulates the
engine torque and pump/motor displacement in order to track a desired velocity profile while maintaining desired
engine conditions. In addition, logic is applied to the MPC to prevent high frequency cycling of the engine. Simulation
results demonstrate the capability of the proposed control strategy to track both a desired engine torque and vehicle
velocity.
Model Recognition and Simulation of an E/H Steering Controller on Off-Road Equipment
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
D. Wu and Q. Zhang and J. F. Reid et al.,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 55-60,
November 1998
view abstract
An automated E/H steering controller is essential for autonomous off-road equipment. This paper presents a methodology for designing the E/H steering controller through a combination of testing and simulation. The steering kinematic model provides the steering linkage gain between the hydraulic actuator and the front wheel. The model makes it possible to close the steering control loop based on the signal of the hydraulic steering actuator rather than the front wheel. Test results were used to identify the non-linear and dynamic characteristics of the original E/H steering system. A Matlab model of E/H steering controller was developed based on the experimental test results.
Model Reduction in Hydraulics by Singular Perturbation Techniques
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
R. Scheidl and B. Manhartsgruber and H. Kogler,
2006, August 2006
view abstract
The requirement to keep mathematical models as simple as possible is contrasted by the power of modern computers by which complex models can be simulated. Particularly in conceptual design the total view must be preserved. The interpretation of simulation results will benefit from a thorough understanding of the system under study, i.e. from the role the diverse physical effects and the main design parameters play for system performance. This requires simple models with a small number of system parameters. Such models either are `designed` properly or are derived from more complex models by proper reduction techniques. For extremely small or big values of some parameters certain effects might practically vanish or reduce to small layers, so called boundary or transition layers. A mathematical technique which focuses on the analysis of such behaviour is perturbation theory, in particular singular perturbation theory. The small fluid compressibility, for instance, makes many hydraulic state equations singularly perturbed systems. Compressibility effects create boundary or transition layers in the time signals especially of pressure. Such layers are triggered either by initial conditions or by a change of the active network topology of the hydraulic circuit due to a switching of a valve. Away from such layers, system behaviour is only weakly affected by compressibility. This view of singular perturbation methods is helpful to figure out the origin and parameter dependence of some effects. The use of such techniques is highlighted by two examples of hydraulic drive systems.
Modern Electrohydraulic Drive Technology for Stationary Machinery in Industrial Automation
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
A. Feuser,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 29-50,
März 2010
view abstract
The hydraulic drive technology has made great strides in the development towards electrohydraulic drive technology. This is valid for stationary applications, but more and more also for mobile machinery. The basis for this is formed by components, which were strongly improved in terms of dynamics and accuracy, such as valves, variable displacement pumps and sensors, as well as the offensive use of powerful digital electronic assemblies, which, in conjunction with the corresponding sensors, knowledge and application of control theory, allow the realization of control loops which are equivalent to electromechanical drives when it comes to dynamics and steady-state accuracy. Hierarchical structures in the control concepts can equally be realized with electrohydraulic axes (Motion Control) and electromechanical axes. The requirements for realizing bus concepts, be it in the control hierarchy or at field level, can be met without any difficulties. Decentralized control architectures, which can thus be set up and replace former central machine controls, offer great advantages and have proven their efficiency in first applications. The allegedly great commissioning effort of set up hydraulic axes can be significantly reduced with pre-set axes with integrated axis control electronics. Apart from valve-controlled axes, new developments were made in conjunction with drives on the basis of variable displacement pumps with improved efficiency. These high developed electro-hydraulic axes are enhanced to aspects of energy efficiency and noise reduction for some time. The feasible drive structures will be expanded to displacement pumps or constant pumps will be connected to speed variable electro-motors respectively. This combination can be applied for instance to a cylinder drive. These axes are high dynamically, precise and energy-efficient. Hydraulic drive systems provide beside functional improvements for the machine building and plant construction industry also a mensurable fee to protect the environment.
Modern Hydraulic Solutions for Production Machines (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
F. Weingarten and P. Malý,
2006,
pp. 41-51,
Mai 2006
view abstract
Hydraulic drives still have their strong presence in production machines. Especially if high
forces have to be sensitively controlled or need to be applied in a limited space the hydraulic
linear drive cannot be beaten.
The growing requirements of modern production equipment nevertheless demands
permanently growing requirements to hydraulic components and drives. Beside the easy
integration into an overall machine control a modern drive has to provide excellent response
and high control quality, has to be energy saving and should integrate multiple functions.
Each connection, which has to be done on site, each necessary manipulation, that has to be
performed by the user, incorporate a potential risk of failure, which can cause significant
delays in the overall system set up.
This paper discusses new approaches to these requirements:
- Faster control valves open new perspectives for even quicker and more precise
actuators.
The combination of well known and proven principle (“voice coil drive”, speaker
actuator) with new materials (rare earth magnets) and new production methods today
allows to realise a valve, robust and cheap like a proportional solenoid and at the
same time providing the response of a servovalve torque motor at a higher force level.
Such valve is presented by proportional valve DFplus Series, developed by Parker
company.
- Extremely fast high performance throttle valves with low pilot power requirements
allow the presses, the casting machines and other large machines to operate even
faster and more precise.
New Parker TDL throttle valves, piloted by above mentioned DFplus valve, cover
a flow range up to 30 000 liter/min ! At the same time these valves offer a step
response between 14 and 24 ms for full stroke !
- New control conceptions for variable displacement piston pumps offer not only energy
saving solutions avoiding the power losses in the system, but at the same time much
improve the response on pressure and displacement control signal too and also
integrate more and more additional functions into one sub-system and reduce the
number of components as well as the risk of improper installation.
Parker PV Series axial piston pumps are coming with these attributes. Various
compensators for pump control can be applied. The response times on control signal
in the range of 25 ms for full stroke of swashplate are achievable when pump
compensator is piloted by high response valve DFplus again.
The example of a hydraulic press with applied above mentioned modern hydraulic
components completes the presentation.
Modern Hydrostatic Drive Systems in the Light of Dynamical Systems Theory
Proc. 4th Conference on Dynamical Systems Theory and Applications, Lodz, 8-9 Dec. 1997
B. Manhartsgruber and G. Riha and R. Scheidl,
1997,
pp. 25-44,
Dezember 1997
view abstract
Dynamic effects in hydrsostatic drives are strongly related to the compressibility of the hydraulic fluid. In a proper nondimensional scaling of the state equations the small compressibility parameter leads to singularly perturbed differential equations. For the hydraulic servo-drive this singular perturbed system is investigated by means of a center-manifold approach. The reduced problem exhibits discontinuities when the servo-valve passes through its zero state. These discontinuities cause transition layers for the pertubed problem. For the resonance converter singular perturbation methods are used to obtain insight inti critical processes which strongly affect the performance characteristics.
Mode Switching And Energy Recuperation In Open−Circuit Pump Control
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
K. Heybroek and J. Larsson and J.−O. Palmberg,
2007,
volume 3,
pp. 197-209,
Mai 2007
view abstract
Today’s mobile machines most often contain hydraulic valve controlled drives in an open loop circuit. For the purpose of saving energy, the constant pressure pumps have in the
past frequently been replaced by load-sensing pumps and load-sensing valves. However, considering applications where the load is helped by the gravitational force, even these hydraulic systems often suffer from poor efficiency. In this article, a novel pump-controlled hydraulic system is studied where energy recuperation from lowering motions is possible.
The pumps are fully displaceable in both directions, working as motors when lowering loads. The amount of recuperated energy is highly dependent on the chosen control strategy,
the hydromechanical properties as well as the target application. Furthermore, the article describes how valve design becomes an important feature in an attempt to reach
high efficiency and machine operability.
Modified Generalized Predictive Control of Networked Systems With Application to a Hydraulic Position Control System
Bo Yu and Yang Shi and Ji Huang,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Mai 2011
view abstract
This paper is concerned with the design of networked control systems using the modified generalized predictive control (M-GPC) method. Both sensor-to-controller (S-C) and controller-to-actuator (C-A) network-induced delays are modeled by two Markov chains. M-GPC uses the available output and prediction control information at the controller node to obtain the future control sequences. Different from the conventional generalized predictive control in which only the first element in control sequences is used, M-GPC employs the whole control sequences to compensate for the time delays in S-C and C-A links. The closed-loop system is further formulated as a special jump linear system. The sufficient and necessary condition to guarantee the stochastic stability is derived. Simulation studies and experimental tests for an experimental hydraulic position control system are presented to verify the effectiveness of the proposed method.
Monitoring of hydraulic systems parameters on the agricultural machines
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
J. Mašek and P. Heřmánek and P. Procházka,
2008,
pp. 184-189,
September 2008
view abstract
Observation of hydraulic circuit parameters can be use for evaluation of instant material feed rate in the harvester. Achieved data create a part of mosaic which together can be used for precision agriculture system. Precision agriculture is the higher level of work on the field by local different condition of soil with optimization of using product factors. The main aim of this system is modification of work operation to local conditions of field. Information about yield during harvesting can be used to produce yield maps. In this way, site specific field management can be done, aiming for higher local economical and ecological yield efficiencies. Site specific yield measurement is fundamental element of the use of precision agriculture. The mass flow monitoring with help of performance parameters on the hydraulic circuit is neglected. This mode of the mass flow monitoring is very perspective according to the historical evolution of the hydraulic systems enforcement on the machines. The measurement system based on a pressure drop in hydraulic circuit for drive the sifting conveyer. Measurement apparatus accuracy depended on a slope of sifting conveyer. Conclusion of our measurement is the possibility of exact measurement of the mass flow on the rod sifting conveyor according to pressure drop on hydraulic motor by different slope of working plane in laboratory conditions.
Monopropellant-Driven Free Piston Hydraulic Pump for Mobile Robotic Systems
Timothy G. McGee and Justin W. Raade and H. Kazerooni,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 75-81,
März 2004
view abstract
The authors present a novel power supply for mobile robotic systems. A monopropellant (e.g., hydrogen peroxide) decomposes into high temperature gases, which drive a free piston hydraulic pump (FPHP). The elimination of fuel/oxidizer mixing allows the design of simple, lightweight systems capable of operation in oxygen free environments. A thermodynamic analysis has been performed, and an experimental FPHP has been built and tested. The prototype successfully pumped hydraulic fluid, although the flow rate was limited by the off-the-shelf components used.
Motion Control for Overconstrained Parallel Servohydraulic Mechanisms
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
A. Plummer,
2007,
volume 3,
pp. 119-131,
Mai 2007
view abstract
A practical position control method is presented for parallel servohydraulic mechanisms in which the payload behaves as a rigid mass. The ability of this method to decouple the
control axes is demonstrated. A modal control approach is used – i.e. the modes of vibration of the table are controlled individually. These modes are dependent on the inertial properties of the table with specimen and the compliance of the actuators due to oil compressibility. In some parallel servohydraulic mechanisms there are more actuators than degrees-of-freedom: i.e. they are overconstrained. It is shown how the proposed control method can be extended to such overconstrained systems. Simulation results are presented based on a validated model of an overconstrained earthquake
simulation table.
Motion Control in Offshore Applications
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
P. Albers,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 281-292,
März 2010
view abstract
Hydraulic drive technology has always been important in the offshore industry because of its robustness, the high power/weight ratio, the reliable technology and the simple operational requirements. There is as of yet no other drive technology available for the often linear movements with high forces and high dynamic movement characteristics. Examples of the hydraulic drives for heave compensation systems will be discussed. It has been shown that these drives, that are classified as large systems, can be calculated on the basis of the known design rules used for smaller systems. Sub-sea hydraulic drives have been and will be used more frequently in the offshore industry. Examples will be discussed in detail of the special techniques available. Also insight will be provided into the hydraulic drives that are being developed for offshore renewable energy systems.
MOVEMENT OF THE CUPS ON THE BARREL PLATE OF A FLOATING CUP, AXIAL PISTON MACHINE
P. A. J. Achten and T. L. van den Brink and J. W. Potma,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 25-33,
August 2004
view abstract
In a floating cup axial piston machine, each piston has its own cuplike cylinder, floating on a barrel plate. On average
the cups and the barrel rotate at the same rotational speed. A closer look at the kinematics of the floating cup principle
however reveals that the cups make a small movement on the barrel plate. The size of this cup trajectory is
strongly dependent on the tilt angle between the barrel and the rotor. Furthermore, the non-uniformity of the joint between
the barrel and the rotor shaft can create an angular difference between the cup and the barrel position. This article
will focus on the combined effect of the barrel tilt angle and the non-uniformity on the cup movement.
Multifunction Hydrostatic Machine as a rotational speed changer
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
M. Banaś and J. Stryczek,
2004,
pp. 9-16,
Juni 2004
view abstract
This paper presents a Multifunction Hydraulic Machine (MHM) and focuses on one of its tasks in the
drive system, namely, changing the rotational speed. The authors of the paper explain the design and
operation of the unit. The presented equations improve the existing model in the low-flow (high speed)
range. The new model has been verified in practice. The operation of the drive system with the MHM has
been investigated. The results of the investigation are presented in the paper and are taken to calculate the
coefficients of the model.
Multi-objective Optimization Tool for Noise Reduction in Axial Piston Machines
Seeniraj, G. K. and Ivantysynova, M.,
In SAE Commercial Vehicle Engineering Congress & Exhibition, Rosemont, IL, USA,
2008,
pp. SAE 2008-01-2723,
view abstract
Noise generation in axial piston machines can be attributed to two main sources; fluid borne and structure borne. Any attempt towards noise reduction in axial piston machines should focus on simultaneous reduction of these two sources. A multi-parameter multi-objective optimization approach to design valve plates to reduce both sources of noise for pumps which operate in a wide range of operating conditions has been detailed in a previous work (Seeniraj and Ivantysynova, 2008). The focus of this paper is to explain the background and to demonstrate the functionality and usefulness of the methodology for pump design.
Multiple Sliding Mode Control for an Electrohydraulic Actuator System
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
El Sayed, M. A. and S. Habibi,
2010,
pp. 353-364,
September 2010
view abstract
This article presents the development of a multiple loop sliding mode control strategy for improving the performance of hydrostatic actuation systems. In these actuators, the presence of nonlinearities associated with pump/motor static friction and backlash, pressure drop in the piping system, and nonlinear friction at the load have a significant effect on the performance and positional accuracy of the system. Earlier studies have indicated that the friction characteristics of the hydrostatic actuation systems are very nonlinear, displaying stick-slip (static-coulomb) type behavior. In trajectory tracking applications, this results in
oscillations near the zero velocity zone.
Sliding mode control was reported to reduce these oscillations by providing a soft adaptive scheme that would compensate for the nonlinear friction. In this article, the concept of sliding control will be extended, by incorporating a secondary inner-loop controller. To enhance the accuracy of tracking in the position and velocity trajectories. Simulation results supported by theoretical analysis indicate that a considerable improvement in performance can be achieved by the implementation of this control strategy.
Multiple-surface sliding controller design for pneumatic servo systems
Y.-C. Tsai and A.-C. Huang,
In Mechatronics,
2008,
volume 18,
pp. 506-512,
November 2008
view abstract
A multiple-surface sliding controller (MSSC) is proposed for pneumatic servo systems with variable payload and mismatched uncertainties. The system is firstly modeled by a non-autonomous dynamic equation with consideration of the valve dynamics. Various nonlinearities and bounded uncertainties are then lumped into two bounded functions to represent the system equation into a formal form for the design of the MSSC so that the mismatched uncertainties can be properly compensated. The closed loop system is proved to have asymptotically stable performace by using the Lyapunov stability theory. Experimental results show that the proposed algorithm is able to give good performance regardless of the uncertainties and time-varying payload.
Nanoscale Friction Dynamic Modeling
Fakhreddine Landolsi and Fathi H. Ghorbel and Jun Lou and Hao Lu and Yuekai Sun,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
November 2009
view abstract
Friction and system models are fundamentally coupled. In fact, the success of models in predicting experimental results depends highly on the modeling of friction. This is true at the atomic scale where the nanoscale friction depends on a large set of parameters. This paper presents a novel nanoscale friction model based on the bristle interpretation of single asperity contact. This interpretation is adopted after a review of dynamic friction models representing stick-slip motion in macrotribology literature. The proposed model uses state variables and introduces a generalized bristle deflection. Jumping mechanisms are implemented in order to take into account the instantaneous jumps observed during 2D stick-slip phenomena. The model is dynamic and Lipchitz, which makes it suitable for future control implementation. Friction force microscope scans of a muscovite mica sample were conducted in order to determine numerical values of the different model parameters. The simulated and experimental results are then compared in order to show the efficacy of the proposed model.
Negative Load Sensing
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
M. Erkkilä and T. Jalkanen and E. Lehto and T. Virvalo,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 497-508,
März 2010
view abstract
This paper presents a novel control system, called negative load sensing, for mobile hydraulics. Opposite to the normal well known load sensing control, where the pressure difference over the input notch is sensed, the pressure difference is in this system sensed and kept constant over the output notch. System characteristics and behavior of negative load sensing are explained for positive and overrunning loads as well as pressure compensation possibilities in the parallel use of multiple users. For practical testing a self-designed and -manufactured, individually controlled four notches - meter-in meter-out – valve, has been used. The characteristics of the valve and the test arrangements are briefly shown and explained. The negative load sensing principle has been tested in the emulations system in order to show the main differences between constant pressure, normal load sensing and negative load sensing systems.
Network-Based Concurrent Engineering-Oriented Simulation Software for Hydraulic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y.-Z. Jin and C.-J. Yang and Y. Chen,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 597-600,
April 2005
view abstract
This research presents network-based concurrent engineering-oriented simulation software for hydraulic system. With Browser/Sewer structure, the software is an integrated design environment which includes user-info management module, expert module, several fundamental hydraulic circuit sets, remote data acquisition module, and math-model-calculate module etc. Once requirements for some circuit are brought forward by a user anywhere anytime, the hydraulic system's schematic drawing can be given. Then parameters of the element in the system are listed for the user to set. Besides that, all the worldwide knowledge and information can be shared, and users can get advice from each other or remote expert on this software platform. Results of practical application indicate that the system can be used to optimize resource from different places to improve the efficiency of product development.
Neural Adaptive Control of a MIMO Electrohydraulic Servosystem
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
H. Zhang and P. Ukrainetz and P. Nikiforuk and R. Burton,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 7-12,
November 1997
view abstract
Electrohydraulic servomechanisms are well known for their fast dynamic response, high power to inertia ratio, and control accuracy. If the system dynamics can be precisely described and the plant dynamics vary in the vicinity of the designed operation point, a fixed parameter controller may be
designed using conventional control theory to acquire the desired output. However, for most industrial systems, it is very difficult to describe the system precisely. In addition, due to disturbances, variations of loads, and changing process dynamics, the system parameters may vary. A neural
network approach, using the parallel distributed processing concept with the capability of an ever-improving performance through a dynamic learning process, provides a powerful adaptation ability; its implementation is thus quite feasible for the control of electrohydraulic servosystems.
The objective of this research was to apply the neural network control architecture to a nonlinear multiple input-multiple output (MIMO) electrohydraulic servosystem to improve its position and force output performance. This objective was achieved through the use of a neural adaptive control scheme.
A neuro-controller was implemented as a subsystem to control the real-time electrohydraulic system so as to track the desired signals defined by a reference model when subjected to system internal interactions and load variations. Experiments were conducted to illustrate the feasibility and benefits of the neural network approach in comparison with the traditional PID control strategies. The position and force outputs of the plant followed the reference model outputs successfully. The proposed control scheme forced the plant outputs to track those of the reference model simultaneously under changes of the load disturbances.
Neural Network Compensated Model-Based Controller for Fluid Power Driven Machines
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
T. Eskola and H. Handroos,
2004,
pp. 131-138,
Juni 2004
view abstract
In this paper, a model-based controller is used to control a hydraulic valve instead of flow feedback control system. Benefit of this is that it is not necessary to use fast and quite expensive flow transducers in the control loop. In an example case an inverse model of a linear hydraulic valve is used for controlling a non-linear valve. A neural network is used for compensating the non-linearity between the controller and the valve. In this paper the controller is test for controlling simulation model, but in the future work it will be applied in real Hardware-in-the-loop (HIL) simulators.
Neurons Adaptive Control Based on Sliding Mode Control Optimized by Fuzzy Logic Inference Applied on a Hydraulic Actuator System
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
Y. Yong and W. Shan and H. Wenmei and K.-E. Rydberg,
2002, Juli 2002
view abstract
In the paper, a neurons adaptive control (NAC) based on a sliding mode control optimized by fuzzy
logic inference has been developed and applied to the positioning control of a hydraulic actuator system.
First, a sliding mode control (SMC) is designed and its parameter is optimized by a fuzzy logic inference
mechanism. Next, according to the input/output data of the above optimized sliding mode control, a
neurons adaptive control is devised and trained on-line based on a sliding mode strategy, which is used as
an adaptive learning algorithm to train the adjustment weights of neurons. Then, the proposed control
strategy is applied to the hydraulic system. The simulation experiment results show that the learning
approach of neurons exhibits robustness characteristics and fast convergence properties and can be
effectively used for on-line control. Simultaneously, the simulation study is provided to illustrate the
feasibility of the proposed training approach. The simulation experiment results also show that the
performance by using the proposed control strategy is much better than that of by using pure SMC. It also
demonstrates the promising potential for developing valuable compound control for nonlinear systems.
New concepts and design of high response hydraulic valves using piezo technology
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
M. Reichert and H. Murrenhoff,
2006,
pp. 401-414,
September 2006
view abstract
A hydraulic valve is a key component which limits reference response and disturbance reaction of a linear drive. The valve should provide the drive with a sufficient volume flow in order to compensate the compressibility of oil and to achieve a feasible cylinder stroke at high operation frequency. The performance of valve depends primarily on the dynamics of electromechanical actuators which drive the valve spool directly or indirectly. The use of fast and stiff piezoelectric actuators as valve drives offers advantages for high dynamic response of the valve and consequently of the whole hydraulic system.
NEW DESIGN OF TRIBOLOGICAL SYSTEMS OF AXIAL PISTON PUMPS WITH COATINGS AND ENVIRONMENTALLY FRIENDLY FLUIDS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
C. Enekes and H. Murrenhoff,
2008,
pp. 294-301,
Juli 2008
view abstract
The Collaborative Research Center 442 “Environmentally Friendly Tribological Systems by Suitable Coatings and
Fluids with Respect to the Machine Tool” (CRC 442) deals with components of tribological systems in machine tools,
e.g. bearings, guidings, gears, hydraulic components and tools. These tribosystems are commonly realized with
biologically questionable lubricants. The CRC 442 aims on the application of biologically fast degradable and
environmentally friendly fluids. The tasks for the application of biofluids focus on the development of new coating
systems and biofluids. Results of these developments are transferred to the tribosystems in machine tools and are tested
close to operational conditions.
The subproject B4 “Tribological Systems in Hydrostatic Displacement Units” is carried out at the Institute for Fluid
Power Drives and Controls of RWTH Aachen University, Germany. It is focused on examinations of the behaviour of
tribosystems in axial piston machines, especially on the tribosystem piston / bushing. It has been shown that this contact
requires detailed examinations to find appropriate coatings and geometries to reduce the loads on the coating by
increasing the contact area. All tribological systems can be examined in a contamination test bench to consider their
interactions and to determine the pump efficiency, especially with contaminated oil.
This paper presents a summary of the preexaminations as well as current works on the new design of all tribological
systems. It will be shown which changes of macro- and microgeometry are required to reach comparable or improved
values of efficiency and durability. Furthermore a survey of the different levels of testing and results will be presented.
New Developments in the Field of Electrohydraulic Drive Technology
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1761-7 (CD-ROM),
A. Feuser,
2007, Mai 2007
view abstract
Due to the stringent technical demands placed on dynamics, precision and flexibility, the machine building sector plays a key role for the various drive technologies. In all variants of drive technology (electrical, mechanical, hydraulic, and pneumatic), the integration of micro-electronics and sensors made it possible to create intelligent drive solutions, which are characterized by greater flexibility, higher reliability and improved accuracy. Micro-electronics leads to
new functionalities, which can be reliably controlled despite higher complexity of the axis movements. In parallel to drive technology, new control concepts of a central and increasingly decentralized structure are being developed and tested.
Through the use of decentralized electronic assemblies with field bus interface in conjunction with a higher-level control, electromechanical, electrohydraulic and electropneumatic axes can be operated simultaneously with their relevant axisspecific
closed-loop control electronics. In the competition with other drive media, fluid power technology can demonstrate its strengths with regard to power density and ruggedness through the consequent integration of control technology
and digital electronics in components and motion axes (Motion Control). Modern control theory, digital electronics and sensorics allow the design of innovative proportional and high-response valves and also variable displacement pumps
featuring high dynamics, precision and reliability for exact metering of the flow so that today extremely powerful electrohydraulic drive solutions are available for stationary and mobile machinery. This article provides an overview of modern electrohydraulic components and drive systems. Mechatronic approaches in the component development as well as an outlook on further developments and application examples round the topic off. Outlooks on computer simulation are
given within the framework of axis representations. Today, simulation is a highly qualified tool for contriving the required new and further developments in theory and for supporting their fast and target-oriented realization.
New Directions in Elastohydrodynamic Lubrication to Solve Fluid Power Problems
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
S. Bair and A. Young,
2010,
volume 1,
pp. 353-361,
Juni 2010
view abstract
Fluid power pumps and motors employ lubricated concentrated contacts. Concentrated contact lubrication (EHL) is
characterized by high contact pressures which deform the surfaces and substantially change the properties of the
hydraulic oils. In an exciting departure from the way in which EHL research has evolved, new film thickness behaviour
is being predicted from material properties before it is observed experimentally. It will be shown that the friction in
full-films can be predicted from the measurable properties of the liquid-a capability that was not available a few years
ago. This new approach is already providing insight into old problems of film formation and friction. These results
show that substantial improvements in full film friction and film formation will result from intelligent engineering of the
fluid properties for a particular application.
NEW DISPLACEMENT CONTROLLED LINEAR ACTUATOR TECHNOLOGY – A SUITABLE CONTROL ELEMENT FOR ACTIVE OSCILLATION DAMPING
Proc. of The Eighth Scandinavian International Conference on Fluid Power, SICFP’03, May 7-9, 2003, Tampere, Finland
R. Rahmfeld, M. Ivantysynova,
2003,
view abstract
This paper deals with the transfer of a new displacement controlled linear actuator technology onto overall mobile machine systems for working hydraulics based on single rod
cylinder and the use for active oscillation damping. The new actuator concept uses alow pressure source for the compensation of the cylinder differential volume. Two pilot
operated check valves make sure that the low pressure side of the cylinder is always connected to the pressurized low pressure line. Great advantages according to the component
expenditure are obtained with this new circuit concept, especially when severallinear actuators are coupled on the low pressure side. The paper presentation will clearly indicate a strong system simplification in contrast to today’s valve controlledsystems. Another part of the paper describes the basic control concept, which was successfully tested in simulation and experiment in four quadrant operations, and the controller design based on a mathematical model of the actuator. Additionally, in this paper a simulation study is presented for the application of a displacement controlled actuator with single rod cylinder for active damping of machine structure vibration. For this
work the linkage system of a wheel loader was modelled with the help of acceleration measurements, whereas a control structure was developed allowing the use of the lifting
actuator simultaneously for active damping purpose.
KEYWORDS: Linear Actuator, Displacement Control, Active Oscillation Damping
New electro-hydraulic control systems for mobile machinery
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
R. Finzel and S. Helduser,
2008,
pp. 309-321,
September 2008
view abstract
The paper outlines a new electro-hydraulic control system for the working hydraulics ofmobile machines. The new control system basically uses the command signals from the joysticks to control the volume flow delivered by the pump. The valves that control the flow for the actuators operate like flow dividers, again controlled by the joystick signal. The new electro-hydraulic system offers better energy efficiency, better controllability and a better damping than hydraulic-mechanical systems supplied today.
New Fluid Qualification Test Results Carried out by a Combination of Flywheel and MPH Tests
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
J. Schmidt and D. Krause and M. Diesselberg,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 355-366,
März 2010
view abstract
The Institute for Product Development and Mechanical Engineering Design (PKT) at the Hamburg University of Technology has developed a new test procedure and a test machine to investigate the lubricating capability of hydraulic fluids. In the future this MPH test (Mechanische Prüfung von Hydraulikflüssigkeiten – Mechanical testing of hydraulic fluids) possibly can substitute the vane-cell-pump test according to DIN EN ISO 20763 (DIN 51389). In this paper flywheel and MPH test results are comparatively described. The combination of flywheel and MPH test allows to analyse changes in the lubricating and wear protecting capability of the test fluid, caused by an endurance application in a high loaded hydrostatic transmission. Furthermore correlations between the results of flywheel and MPH test were discussed, e.g. between the contamination of pump and motor leakage oil, caused by wear of the hydrostatic transmission and the wear of the MPH test specimen. Both, flywheel and MPH test were briefly described within this paper.
New Hydraulic Products and Technology in Kayaba Industry CO., Ltd.
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
K. Inoue,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 43-50,
April 2005
view abstract
Today, environmental issue and combination with electric and electronic technology are most important subjects in fluid power industry. Concerning to these, some newly-developed hydraulic products and technologies in Kayaba industry Co., Ltd. are introduced.
New Innovative Components for Energy Efficient Working Hydraulics in Mobile Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
R. Lasaar and A. Stoll,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 37-52,
März 2010
view abstract
Many current hydraulic systems in mobile machines still have a set of fixed displacement pumps for the working functions lifting, tilting, steering, pilot oil supply and other functions. This paper introduces a highly efficient and dynamic working hydraulic circuit design with two new hydraulic components, an electrically actuated medium duty pump and an electro-hydraulic laminate type directional control valve, which both offer various innovations like dynamic response, a high level of accuracy, minimum installation space, low noise emission and high rotational speeds.
New Nonlinear Robust Control Concept for Electro-Hydraulic Drives
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
J. Komsta and P. Antoszkiewicz and T. Heeg and J. Adamy,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 497-508,
März 2010
view abstract
This paper discusses problems of the position control of electro-hydraulic drives in the presence of unknown disturbances and uncertain plant parameters. Due to the strong nonlinearities of the system, more sophisticated control algorithms are recommended if an optimal closed-loop dynamic behaviour and high positioning accuracy are required. In order to overcome the system nonlinearities and to assure robustness against disturbances and plant uncertainties, a Sliding Mode Controller and an Integral Sliding Mode Disturbance Compensator were developed and experimentally tested. Also, the industrial applicability of the new algorithms was the scope of the investigation. The test results confirm a very good tracking performance and the robustness against external disturbances and model uncertainties.
NEW RESULTS IN CONTROL SYNTHESIS FOR ELECTROHYDRAULIC SERVOS
I. Ursu and F. Ursu,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 25-38,
November 2004
view abstract
This survey presents some recent results of the authors in the field of the control synthesis for electrohydraulic servos.
Three are the methodologies of control theory herein considered. Firstly, an integrated methodology of robust control synthesis with antiwindup feedback compensation for linear model of electrohydraulic servo is developed. Secondly,
in a strongly nonlinear framework, an integrated fuzzy supervised neurocontrol is proposed. This represents a
control strategy which is in fact independent of mathematical model of the systems, thus achieving certain robustness
and reducing complexity. At last, the backstepping is used for obtaining of control laws for asymptotic tracking of position
or force references in the case of a certain model of an electrohydraulic servo. Conclusive numerical simulations
are provided to verify the behaviour of the controlled systems by the proposed control laws.
New Swash Plate Damping Model for Hydraulic Axial-Piston Pump
X. Zhang and J. Cho and S. S. Nair and N. D. Manring,
In Journal of Dynamic Systems, Measurement, and Control,
2001,
volume 123,
pp. 463-470,
September 2001
view abstract
A new, open-loop, reduced order model is proposed for the swash plate dynamics of an axial piston pump. The difference from previous reduced order models is the modeling of a damping mechanism not reported previously in the literature. An analytical expression for the damping mechanism is derived. The proposed reduced order model is validated by comparing with a complete nonlinear simulation of the pump dynamics over the entire range of operating conditions.
New Trends Required New Hydraulic Media
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
G. Gaule,
2007,
volume 2,
pp. 383-399,
Mai 2007
view abstract
Since 1905 hydraulic oils have been used as transmission media. With about 86 % mineral oil based hydraulic fluids clearly dominate the market. The remaining 14 % are equally divided up into synthetic and hardly inflammable media. Since 1990 the demand for biodegradable oils (so-called bio oils) has been steadily increasing. For this reason the technical guidelines of VDMA 24568/ISO 15380 have been created.
According to these guidelines biodegradable hydraulic media are divided into the categories HEES, HEPR, HEPG and HETG. These technical minimum requirements for “bio-oils” are still valid today. When selecting a “bio-oil” the user has to consider the product characteristics of the medium concerning hydrolysis/oxidation stability, low-temperature behaviour and elastomer compatibility as well as the recommended operating temperature range according to DIN EN ISO 15380 chart 1. Furthermore a holistic view should consider expected reciprocal effects so that in a life cycle balance a positive value can be expected. lt is generally true that eco-labels are not based on a technical norm and do not at all represent a differentiation between “bio” or “not-bio”. Rapid biodegradability does not always mean environmental protection, because quick biodegradation can result in a substantial de-oxidation of the environment which may result in serious consequences for plants and small organisms. Media, for which the dismantling rate can be variably defined are on the increase for the medium and long term.
Next generation simulation software using transmission line elements
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
M. Axin and R. Braun and A. Dell'Amico and B. Erikkson and P. Nordin and K. Petterson and P. Krus,
2010,
pp. 265-276,
September 2010
view abstract
A suitable method for simulating large complex dynamic systems is represented by distributed modelling using transmission line elements. The method is applicable to all physical systems, such as mechanical, electrical and pneumatics, but is particularly Well suited to simulate systems where Wave propagation is an important issue, for instance hydraulic systems. By using this method, components can be numerically isolated from each other, which provide highly robust numerical properties. It also enables the use of multi-core architecture since a system model can be composed by distributed simulations of subsystems on different processor cores.
Technologies based on transmission lines has successfully been implemented in the HOPSAN simulation package, develop at Linköping University. Currently, the next generation of HOPSAN is developed using an object-oriented approach. The Work is focused on compatibility, execution speed and real-time simulation in order to facilitate hardware-in-the-loop applications. This paper presents the Work progress and some possible features in the new version of the HOPSAN simulation package.
NNPID Applied in the Hydraulic AGC System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Wang and H. Wang and W. Zhang and D. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 726-730,
April 2005
view abstract
A new neural network PID (NNPID) controller, which is based on PID by means of neural network's ability of self-learning and adaptive, is presented. The NNPID controller is designed by combining neural network with PID control strategy. Additional momentum method, that is an improved BP algorithm, is used in the neural network is analyzed. This paper presents the control for the highly nonlinear, time-varying hydraulic AGC of rolling mills based on the NNPID controller. The simulation shows that the dynamic quality of the system is improved, and NNPID has good adaptability.
NOISE REDUCTION IN AXIAL PISTON MACHINES BASED ON MULTI - OBJECTIVE OPTIMIZATION
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
G. K. Seeniraj and M. Ivantysynova,
2008,
pp. 111-123,
Juli 2008
view abstract
This paper details the doctoral research on noise reduction in axial piston machines. The focus of the research is to
investigate ways to reduce fluid borne and structure borne noise sources simultaneously and develop a methodology to
help design quieter pumps. The investigation has led to the development of a multi-parameter multi-objective
optimization approach to design valve plates for pumps which operate in a wide range of operating conditions. The
main focus of this paper is to explain the optimization methodology in detail. The paper also includes discussion on
factors that need to be considered while providing relief grooves as a reduction technique.
NOISE REDUCTION IN AXIAL PISTON MACHINES BASED ON MULTI-PARAMETER OPTIMIZATION
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
G. K. Seeniraj and M. Ivantysynova,
2006,
volume 1,
pp. 235-246,
Juni 2006
view abstract
The fluid power industry is well aware of the noise generated by axial piston machines. The noise generated by these
machines can be broadly grouped under fluid borne noise and structure borne noise. This paper discusses a systematic
as well as a unified approach to noise reduction. Most of the noise reduction techniques that are available today focus
on only one type of noise, either fluid borne or structure borne. But trying to reduce noise due to one of the mentioned
sources, with a particular technique, has an influence on the other source. This work discusses the results of
investigation of reduction techniques and its effect on fluid borne noise, structure borne noise and volumetric efficiency.
Also, a multi-parameter optimization strategy for axial piston machines which includes fluid borne noise, structure
borne noise and volumetric efficiency is detailed.
Noise Reduction of Axial Piston Pumps using Variable Reversing Valves
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-91-4,
T. Nafz and H. Murrenhoff and R. Ruslan,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 2,
pp. 267-278,
März 2010
view abstract
Noise reduction is a main target of pump development. The main criteria for noise generation of an axial piston pump are the flow ripple, the oscillation of the axial piston force and the oscillation of the swash plate torque. Using special reversing valves, a primary approach to reduce noise is investigated in this paper. Such a variable reversing process allows for an active reaction to changes in operating conditions such as swash angle, speed and delivery pressure. In order to investigate such an actively controlled valve plate configuration, a simulation model in AMESim was built and verified with cylinder pressure measurements and flow ripple measurements. Therefore a specific test stand with an anechoic ending and a pressure transducer in the pump cylinder was built. A suitable design for the variable reversing valves needed to be found, providing continuously variable valve openings between the reversing areas and the delivery kidney as well as the suction kidney. Various control strategies can be applied to this system. In this paper, the pump noise strategy and the flow ripple strategy are described in more detail. Measurement and simulation results of both strategies are presented and compared to the grooved standard valve plate in order to show the huge potential of this variable system.
Nonlinear Adaptive Learning for Electrohydraulic Control Systems
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
D. Zheng and H. Havlicsek,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 83-90,
November 1998
view abstract
This investigation presents the application of an existing adaptive learning rule to the position control of a hydraulic cylinder driven by an electrohydraulic proportional valve. The system is representative of many types of Manufacturing applications including Injection Molding, Metal Forming and Industrial Presses which perform the same operation repeatedly for many cycles. The system contains several major nonlinearities that limit the ability of simple controllers in achieving satisfactory performance. These nonlinearities include: valve deadzones, valve flow saturation, and cylinder seal friction. Furthermore there is a significant compliance in the system due to the hose length between the valve and the cylinder. The learning algorithm iteratively determines an appropriate feedforward signal to be used in conjunction with simple feedback in order to track a predetermined reference signal. The algorithm is presented along with simulation and experimental results.
Nonlinear Adaptive Robust Control of One-Dof Electro-Hydraulic Servo Systems
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
B. Yao and G. T.-C. Chiu and J. T. Reedy,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 191-197,
November 1997
view abstract
This paper intends to provide a theoretic framework for the high performance robust control of electro-hydraulic servo-systems.
This is achieved through applying the recently proposed adaptive robust control (ARC) while taking into account the particular nonlinearities and model uncertainties of the electro-hydraulic servo-systems. In particular, the robust motion control of a typical electro-hydraulic servo-system will be considered. The system consists of an inertia load driven by a double rod cylinder regulated by a two-stage servovalve. The paper will consider the effect of both parametric uncertainties coming from the inertia load and the cylinder and the uncertain nonlinearities such as
friction forces. Non-differentiability of the inherent nonlinearities associated with hydraulic dynamics is examined and strategies are provided for handling the non-differentiability of the control term due to the direct change of valve opening when doing backstepping design via ARC Lyapunov function. The resulting controller
guarantees a prescribed transient performance and final tracking accuracy in the presence of both parametric uncertainties and uncertain nonlinearities while achieving asymptotic tracking in the presence of parameteric uncertainties.
Nonlinear Control of Hydraulic Servo Drives Based on a Singular Perturbation Approach
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 1998
B. Manhartsgruber and R. Scheidl,
Professional Engineering Publishing,
ed. C. R. Burrows and K. A. Edge,
1998, September 1998
view abstract
The excellent dynamic capabilities of hydrostatic drives with a conventional linear control design are bought at the expense of a poor energetic efficiency. This paper presents a novel approach towards the control of motion of a heavy mass driven by a hydraulic cylinder with a fast valve. The dynamics of the drive are described by a singularly perturbed system of ordinary differential equations. A singular perturbation analysis of this mathematical model results in the suggested control method. Special attention is paid to the compensation of the dry friction at the hydraulic cylinder.
Nonlinear Dynamic Model of a Two-Stage Pressure Relief Valve for Designers
Pei-Sun Zung and Ming-Hwei Perng,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 62-66,
März 2002
view abstract
This paper presents a handy nonlinear dynamic model for the design of a two stage pilot pressure relief servo-valve. Previous surveys indicate that the performance of existing control valves has been limited by the lack of an accurate dynamic model. However, most of the existing dynamic models of pressure relief valves are developed for the selection of a suitable valve for a hydraulic system, and assume model parameters which are not directly controllable during the manufacturing process. As a result, such models are less useful for a manufacturer eager to improve the performance of a pressure valve. In contrast, model parameters in the present approach have been limited to dimensions measurable from the blue prints of the valve such that a specific design can be evaluated by simulation before actually manufacturing the valve. Moreover, the resultant model shows excellent agreement with experiments in a wide range of operating conditions.
Non-Linear Dynamics of a Hydraulic Piston Pump Model with Long Suction Line and Cavitation
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2003
B. Manhartsgruber,
2003,
pp. 253-264,
Nonlinear Force/Pressure Tracking of an Electro-Hydraulic Actuator
Rui Liu and Andrew Alleyne,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 232-236,
März 2000
view abstract
In this paper, a Lyapunov-based control algorithm is developed for the force/pressure tracking control of an electro-hydraulic actuator. The controller relies on an accurate model of the system. To compensate for the parameter uncertainties, a standard parameter adaptation based on Lyapunov analysis is applied. The control law is coupled with the adaptation scheme and applied to an experimental system. Friction modeling and compensation for pressure tracking are discussed and experimental results shown. The results show that the nonlinear control algorithm together with the adaptation scheme gives a good performance for the specified task.
Nonlinearity and Feedback Compensation Method in a Pneumatic Vibration Generator
B. Kuzniewski,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 163-167,
März 2000
view abstract
The paper presents a model of a pneumatic piston unit and analyzes dynamic processes taking place in the unit generating periodic signals. Nonlinearities and feedback occurring in flow and vibration processes are determined. A method of nonlinearity and feedback compensation by input parameters of air streams is presented.
Nonlinear Model-Based Control of Pulse Width Modulated Pneumatic Servo Systems
Xiangrong Shen and Jianlong Zhang and Eric J. Barth and Michael Goldfarb,
In Journal of Dynamic Systems, Measurement, and Control,
2006,
volume 128,
pp. 663-669,
September 2006
view abstract
This paper presents a control methodology that enables nonlinear model-based control of pulse width modulated (PWM) pneumatic servo actuators. An averaging approach is developed to describe the equivalent continuous-time dynamics of a PWM controlled nonlinear system, which renders the system, originally discontinuous and possibly nonaffine in the input, into an equivalent system that is both continuous and affine in control input (i.e., transforms the system to nonlinear control canonical form). This approach is applied to a pneumatic actuator controlled by a pair of three-way solenoid actuated valves. The pneumatic actuation system is transformed into its averaged equivalent control canonical form, and a sliding mode controller is developed based on the resulting model. The controller is implemented on an experimental system, and the effectiveness of the proposed approach validated by experimental trajectory tracking.
Nonlinear Optimal Control of a Hydraulically Actuated Positioning System
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
T. W. McLain and R. W. Beard,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 163-168,
November 1997
view abstract
In this paper, the nonlinear optimal control problem is formulated for the position control of an electrohydraulic servo system. The optimal control is given by the solution to the Hamilton-Jacobi-Bellmann equation, which in this case cannot be solved explicitly. An alternative method, to obtain an approximate optimal solution. Preliminary simulation results, demonstrating the application of this approach to the position control of a hydraulically actuated device, are presented.
Nonlinear Robust Control of an Electro-hydraulic Positioning System
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
T. W. McLain and R. W. Beard,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 119-125,
November 1998
view abstract
In this paper, a novel approach for the formulation of nonlinear H∞ control laws is applied to the position control of an electro-hydraulic servo system. These robust controllers are obtained by numerically approximating the solution to the Hamilton-Jacobi-Isaacs (HJI) equation and result in nonlinear control laws in feedback form. The approximation is accomplished by a two-step successive Galerkin approximation strategy. The application of this approach to the control of a hydraulic positioning system with uncertain fluid bulk modulus and density is described.
Numerical Analysis of a Measure to Improve the Suction Performance of Hydrostatic Pumps
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
N. Bügener and S. Helduser and J. Weber,
2010,
volume 2,
pp. 551-559,
Juni 2010
view abstract
The paper deals with a measure to improve the suction performance of hydrostatic pumps to increase their speed limit
by reducing cavitation. Using a Helmholtz resonator at the suction duct of a pump the suction pressure pulsation can
significantly be reduced and hence the inlet pressure losses. The numerical flow analyses were carried out with the
commercial CFD-software ANSYS FLUENT, which are compared with experimental investigations. For the example of
an axial piston pump the suction pressure pulsation could be reduced to 60% of the original pulsation, whereas the
minimum suction pressure, which is most determining for the cavitation intensity were increased by 60%.
Numerical Analysis of the Dynamic Behaviour of Piston Journal Bearing in Axial Piston Pumps and Motors
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
E. Specchia and B. Zardin and M. Borghi,
2010,
volume 1,
pp. 237-248,
Juni 2010
view abstract
This work presents a numerical analysis of the piston dynamic behaviour in axial piston swash plate type pumps and
motors. The numerical method adopted is based on the solution of the piston motion equations which depend on the
pressure distribution within the cylinder-piston gap. In order to determine this contribution, the Reynolds equation is
applied in the lubricating fluid film between the piston and the cylinder. Besides the piston dynamic behaviour, the
model permits to calculate the leakage flow through the gap and the friction forces acting on the piston and cylinder
surface.
After the presentation of the numerical procedure, the dynamic behaviour of the piston is firstly discussed, highlighting the stability of the bearing.
This work is part of a wider research activity focused on the study of positive displacement machines, with the aim to
determine and maximize their global efficiency.
Numerical Analysis of the Flow Field around a Ribbed Helix Lip Seal
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
C. K. Wen and A.S. Yang and C.S. Tseng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 257-261,
April 2005
view abstract
In this study, a direct numerical simulation model has been developed to aid in the understanding of the pumping mechanism of a ribbed helix lip seal. A SIMPLEC numerical algorithm with the staggered-grid arrangement is employed to simulate the flow field around the contact region between the lip and the shaft in the environment of a pumping-rate test rig, where both air and oil sides are filled with oil initially. The streamline pattern and pressure field are examined. Complicate three-dimensional streamline topology is analyzed. The vortex generated next to the lip on the oil side rotates such to create an inward pumping effect. On the air side, pressure built up on the windward faces of ribbed helices next to the lip also help pumping oil back to the sump. The pumping rates are calculated at shaft speeds, ranging from 1000 to 6000 rpm, and compared to the measured values from the test rig. Good agreement is observed. Both calculated and measured pumping rates increase as shaft speed and sump temperature increase and as the sealed fluid viscosity decreases. The current results demonstrate the promising application of CFD in the design of radial lip seals.
Numerical analysis of the hydraulic circuit of a commercial common rail diesel fuel injection system
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
P. Beierer and K. Huhtala and M. Vilenius,
2007,
pp. 159-173,
September 2007
view abstract
The trend in modern diesel combustion engine technology aims for fast acting injection systems that operate at pressures of 1500 bar and more. The Common Rail (CR) system is one typical representative of this development. It offers maximum flexibility in respect to injection pressure and timing. Due to these characteristics new challenges arise which need to be tackled if the full potential of this technology is to be used.
This paper introduces a numerical model of a commercial CR diesel fuel injection system. The analysis is made mainly in 1D and partly in 3D. The simulation results are compared to measurements. Finally, the model is used to perform a parameter study of the hydraulic circuit.
Numerical Analysis of the Lateral Forces Acting on Spools of Hydraulic Components
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
M. Borghi and G. Cantore and M. Milani and R. Paoluzzi,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 149-156,
November 1998
view abstract
This paper deals with the analysis of pressure distribution
within the fluid film in the clearance between spool and sleeve of hydraulic components, in order to predict the value of the locking force induced by unbalanced pressure acting on tapered geometries.
Particular care is devoted to the investigation of the lateral
force dependency on clearance and eccentricity of the spool.
Some theoretical results are presented, obtained solving (by the finite difference method) the two dimensional Reynolds equation for the fluid film. These results are then compared to those deriving from a generally adopted predictive formula. Results show remarkable differences, up to 70 %, in presence of high values of eccentricity.
Moreover, an analogous Reynolds' based solution is performed
for a tapered geometry of the spool with one balancing groove, with particular attention to the influence of its length and position on resulting locking force and leakage flow.
Also the locking force reducing effect of a balancing groove is characterized, and a saturated behavior when the groove is placed very close to the high pressure spool side has been found.
Numerical analysis of the lubricating gap between bushes and gears in external spur gear machines
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Zecchi, Marco and Vacca, Andrea and Casoli, Paolo,
2010,
pp. 397-416,
September 2010
view abstract
This paper presents a numerical model for the description of the flow field in the lubricating gaps between gears and sliding bushings (or bearing blocks) in external spur gear machines. These lubricating gaps strongly affect the unit (pump or motor) performance: the leakage flow influences its volumetric efficiency, while the friction losses can lead to poor hydromechanical efficiencies. Moreover, the balance of the forces acting on the sliding elements necessary to achieve high durability and reliability of the unit is based on the pressure field established in the lubricating gap. In this work the lubricating gap is solved considering the Reynolds eq., including all terms related to a possible tilt between the elements and to the squeeze effect (due to the
micromotions of the parts), in order to achieve a detailed description of the flow field and of the carrying ability of the interface. A relevant effort was directed towards
the development of an automatic procedure able to define the computational mesh and solve the flow field in the lubricating gap for each angular position of the gears
starting directly from the CAD drawings of the machine. The developed code considers also the effects of the recesses usually machined on the sliding elements. Starting from the knowledge of the pressure in each tooth space volume (calculated using an external tool) the model not only permits a deep description of the flow field into the lubricating gap, but it also allows the calculation of the overall reaction forces exerted on the sliding elements. On the basis of these forces, considerations about the correct balance of these elements can be done. Besides the details concerning the model implementation, the paper presents its potentials assuming some simplifications about the motion of the sliding elements.
Numerical and Experimental Analysis of the Hydraulic Circuit for the Rear Hitch Control in Agricultural Tractors
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
P. Casoli and A. Vacca and A. Anthony and G.L. Berta,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 51-63,
März 2010
view abstract
This paper describes the mathematical modeling of a tractor rear hitch control valve (HCV). The HCV operates in two modes namely lifting and lowering. The lifting circuit incorporates a pressure compensated flow control valve, while the lowering circuit is gravity assisted. The HCV incorporates a load-sensing system; load-sensing systems and pressure compensated valves are classified as feedback systems. The
objective of this study is to develop a complete mathematical model of the HCV. This would help to better understand its functionality and to quantify the energy losses across its components. This paper presents the first results of the study.
Numerical and Experimental Investigation of Cavitating Flow in Water Hydraulic Seat Valve
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
T. Leino and K. T. Koskinen and M. Vilenius,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 463-467,
April 2005
view abstract
One difference in the use of oil and water hydraulics is the sensitivity to cavitation occurrence in the system. The difference is emphasised with temperature rise of the fluid. A probable place for the cavitation appearance is a valve including orifice and strong gradients of the pressure.
Experimental and numerical investigation of the flow characteristics of water hydraulic seat valve has been made. The valve is non-commercial particularly made for this special purpose. It is cut along its symmetry axis and covered by a sheet of transparent plastic to get the flow visible. Operation of the valve has been in the range where cavitation occurs in the downstream side of the valve orifice. The cavitation has been investigated visually and detecting sound pressure outside the valve. Flow rate and pressures in the turbulent orifice of the valve are measured in a steady state.
Shapes and opening of the valve are varied in the study and the goal has been to get basic information of the influence of different parameters to the valve operation, especially looking the cavitation phenomenon. Variation in shapes means the use of sharp or chamfered edge on seat corner and the use of conical or ball-shaped poppet head. For this phase of study. a three-dimensional model of fluid dynamics has been used to simulate the system.
The results of numerical fluid dynamic simulation are compared to the experimental ones. The experiment has shown the meaning of the valve structure to the cavitation behaviour and flow characteristics. The used method of computational fluid dynamics is not giving the appearance of the cavitation correctly. It also has the difference in the
flow rate compared to the measured value. In the view of that fact, it is reasonable to look this method with
reservation when trying to model occurrence of cavitation in an orifice.
NUMERICAL CHARACTERIZATION OF PIPES AND HOSES DYNAMIC RESPONSE
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
M. Borghi and M. Milani and F. Paltrinieri and B. Zardin,
2006, August 2006
view abstract
This paper deals with the study of pipes and hoses dynamic characteristics variation with the fluid-wall equivalent bulk
modulus description, with particular attention devoted to the analysis of the wall thickness, of the mechanical constraints
and of the internal pressure effects both on the fluid celerity, and on the pipe frequency response. In particular,
considering both the case of plain stress and of plain strain, the pipe wall compliance and bulk modulus are firstly derived
as a function of the internal pressure and of the wall elastic and geometrical characteristics. Then, the influence of
the pipe geometry and of the wall thickness on the pipe wall compliance and bulk modulus are highlighted for some
materials of interest for industrial, automotive and aerospace applications (steel, aluminium, titanium and wired rubber),
and the dependency of the equivalent bulk modulus on these parameters and on fluid physical characteristics is
highlighted. Finally, the influence of mechanical constraints, of pipe geometry, of fluid physical properties, of wall
material and of fluid pressure on the global pipe dynamic response characteristics, and in particular on the fluid celerity,
on the Mach number and on the natural frequency, is evidenced.
Numerical Control of the Electrohydraulic Servomechanisms
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
O. Dragos and V. Nicolae,
2004,
pp. 373-380,
Juni 2004
view abstract
The paper contains a short report on the theoretical and experimental activities aiming to create a new type of digital electro hydraulic servomechanisms used for controlling the speed of the hydraulic turbines. Hardware design problems, control software design, and experimental validation are briefly presented. The main feature of the new structure is the use of high-quality industrial electro hydraulic and electronic components only, in order to avoid manufacturing difficulties, high prices, and the manufacturer permanent technical assistance need. The authors present the peculiarities of the ADwin industrial process computer, the software packages and programming languages it supports. The actual performance of the prototype was found in good agreement with the theoretical prediction, and CEI demands.
Numerical Modeling of Unsteady Flow, Cavitation and Noise Generation in Hydraulic Valve (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
T. Blejchař and M. Kozubková,
2006,
pp. 238-247,
Mai 2006
view abstract
This paper deals with modeling of the unsteady fluid flow, cavitation and sound propagation
in the hydraulic valve. The hydraulic valve (Fig. 1) emits sound about frequency 8-10 kHz in
working state. The generated sound is the main shortcoming of the valve. An experimental
measurement of the flow in this valve is very complicated or impossible near the throttle area.
The numerical simulation can give information about flow field and flow instabilities in the
throttle area eventually. The diameter of the spool is only 10 mm in this case.
The noise is generated by an unsteady flow near shape edges of the spool and the channels.
Main part of the control level is a cone, it indirectly regulates opening of valve. As it was
said, the noise is generated in a throttle area, so that the flow in a power level is only
simulated, therefore there is used geometry of the spool, the bush, the chamber, and the piece.
Current mathematical model of turbulence, sound emission and diffusion and fast Fourier
transformation are applied to prediction and interpretation of noise.
The basic equations describing laminar and turbulent regime of the flow bring out the
application of the main physical laws. The set presents four differential equations. (Three
Navier-Stokes equations and one continuity equation). Direct numerical simulation DNS is
very sophisticated method and it cannot be used for solution of a common technical problem.
That is why simpler methods are used to simulation. The simpler mathematical models are
called turbulent models. Two different models were used to simulation, namely Laminar and
Large-Eddy-Simulation LES. The Laminar model was conjuncted with cavitation model.
The noise is probably generated by unsteady flow in a throttle area. Two monitor points are
located in channel near shape edges, near channel edge and second near spool edge. The
flow field instability in the channel evokes pressure fluctuation (Kármán vortex
shedding)(Fig. 2). The vortices were created near shape edges of the spool and the channels.
Low pressure domain was near the shape edge. It can provoke a cavitation, which can be next
noise source as far as it is generated sound by cavitation.
NUMERICAL OPTIMIZATION OF A DISTRIBUTOR VALVE
L. Dahlén and P. Carlsson,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 17-25,
November 2003
view abstract
In this paper a non-linear optimization method is used to improve the design of a distributor valve. The distributor
valve is an important component in a radial piston hydraulic motor, and optimization of the design to minimize power
losses is an interesting way to increase efficiency. The main function of a distributor valve is to supply the pistons with
a pressurized flow and to return oil during rotation. At the same time the distributor valve acts as an externally pressurized lubricated thrust bearing, in order to separate the rotating parts from the motor case. The bearing acts as a hydrostatic annular multi-recess plane thrust bearing, with different recess pressures. The separating force of the bearing is balanced hydrostatically by the pressure that is applied and springs. Losses will occur in the contact between the parts in
the distributor valve, due to friction and leakage.
This paper shows that modern optimization methods can be used as an effective tool to create new designs and to
modify the existing design of the bearing surface geometry of the distributor. A finite element method has been used to
simulate the contact, and the program is linked to an optimization routine to perform the optimization. The results of the optimized design show a significant decrease in power loss, compared to the existing design in the operating range.
Numerical Simulation and Experimental Investigation on Turbulent Flow Characteristics in the Circulative Impinging Stream Reactor
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Zhang and J. Liu and K. Wang,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 425-429,
April 2005
view abstract
The turbulent flow characteristics of the impinging stream reactor were calculated with a standard k – ε turbulence model which solved by finite element method. The velocity field, pressure field, the distributions of
turbulent energy and its dissipation rate at various conditions were obtained, the changes of these parameters in impinging zone were studied in detail. The simulation results of pressure distribution were compared with the measured and agreed well with the current experimental measurements. The present works show that velocity and pressure distributions in circulative impinging reactor are symmetrical with impinging plane and axis of the flow distributor; there are some dead bands at two sides of the flow distributor, and decrease with Reynolds number increasing; the energy dissipation rate is faster in impinging zone than other zones, it is contributed to heat and mass transfer.
Numerical Simulation and Experiments on the Flow in a Multistage Centrifugal Pump
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
F.- K. Benra and J. Feng,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 430-434,
April 2005
view abstract
In this paper, a numerical simulation of the first stage of a multistage centrifugal pump, consisting of an impeller, a diffuser and a return channel, is performed by the commercial software CFX-5. The obtained simulation results are compared with experiments, which are done in a test facility which has been especially prepared for optical flow measurements.
For the numerical simulation, a structured grid for the impeller part is created by CFX-TurboGRID and a structured grid for the diffuser and the return channel is obtained by applying the grid generator ICEM-CFD. Then, the Reynolds Averaged Navier-Stokes (RANS) equations are solved by the software CFX-5 with a stage interface between rotating and stationary frames. For the stage interface, the flow behind the impeller is averaged circumferentially to be the inflow conditions of the diffuser blades.
In order to validate the numerical simulation results, experiments are designed and conducted by Laser Doppler Velocimetry (LDV) in the diffuser region. The experimental investigations support the simulation results and CFX-5 is proven to be of capable of capturing the existing flow phenomena under the given constraints.
Numerical Simulation of Friction at Hydraulic Rod Seals
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
O. Heipl and A. Wohlers and H. Murrenhoff,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 379-390,
März 2010
view abstract
Seals are important machine elements to ensure the functionality of hydrostatic devices like cylinder applications. A wrong dimensioned sealing system leads to raised friction and large leakage. At present there is no established calculation method to predict the dynamic seal process. In this paper a general simulation approach based on physical models is explained. The item of investigation is a profile ring. Using a steady-state structural mechanics Finite Element Analysis (FEA) the contact pressure between the profile ring and the rod is calculated. The contact pressure profile is applied as a starting condition for the subsequent dynamic simulation which is based on a Fluid-Structure Interaction (FSI). Hydrodynamic pressures and dynamic contact pressures are considered as well as the seal deformation. The simulation result is shown for a pressureless operation condition. In further investigations the model will be validated extensively by measurements and will be expanded towards more general operation conditions.
Numerical simulation of pulsating flow in resonator hose based on measured data of wave speed
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
I.-Y. Lee and M.-G. Kang and J.-W. Kim,
2007,
pp. 383-396,
September 2007
view abstract
In this study, a new method for analyzing pulsating flow in hose based on wave speed data in hose is suggested. Then a new method to measure wave speed in hose(viscoelastic pipe) ‘closed-end-conduit with three transducer method’ proposed by the authors is explained in detail. Using the proposed wave speed measuring method, wave speed data in each component of the object resonator hoses are measured through preliminary experiments. Finally, with several object resonator hoses, pressure attenuation characteristics are investigated by experiments and simulations, to show the validity of the suggested method for analyzing pulsating flow in resonator hose.
Numerical simulation of the 3-D turbulent steady compressible flow in type “T” junctions and experimental validation of the total pressure loss coefficient
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
I. Murcia Murcia, J. Pérez García,
2004,
pp. 357-371,
Juni 2004
view abstract
Nowadays, simulation models of steady and transient compressible internal flow are essential in analysing
devices and plants where piping systems for gases and steam are required, such as, pneumatic fluid power
systems, transport piping systems, inlet and exhaust systems in alternating combustion engines and
compressors. Models used in the simulation of steady and transient compressible flow in junctions require
local total pressure loss coefficients. These coefficients can be experimentally obtained although a
experimental support highly cost is required. Moreover, the internal flow behaviour is unknown.
Alternatively, these coefficients can be obtained through numerical simulation using a 3D CFD general
purpose software adequately validated.
This work is aimed to numerical simulation of 3D steady compressible flow at junctions “T” type. The
geometrical characteristics and the different types of mesh used during simulations will be described, as
well as numerical schemes, turbulence models, boundary conditions and more adequate simulation
hypothesis. The applied procedure to experimental validation of the numerical results for the total pressure
loss coefficient in steady compressible flow in “T” type junctions will be presented. The experimental
results were obtained in a flow bench for several combining and dividing flow configurations and for
different mass flow ratios between branches as a function of local Mach number at intersection point in
the common branch. The comparison of numerical results with experimental and reference data, allow us
selecting and adjusting simulation parameters, such as optimal turbulence model, boundary conditions,
grid sensitivity and size, as well as most suitable adaptation method in each case, discretization model and
algorithm to solve the equations.
Numerical Study of Joule Heating Effect on Electroosmotic Flow in Rectangular Microchannels with Different Aspect Ratios
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Z. Peng and Z. Chuncheng and Z. Deyi and C. Hongli and P. He and W. Jun and W. Di,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 407-410,
April 2005
view abstract
Joule heating effect on the temperature fields during electroosmosis in glass and PDMS polymer-based rectangular microchannel is numerically investigated in this paper. The mathematical model on Joule heating effects includes Poisson-Boltzmann equation governing the Electric Double Layer field, the modified Navier-Stokes equations governing flow field and the energy equation governing the temperature field due to Joule heating. These fields are strongly coupled via temperature dependent liquid properties. Computations for the temperature field during electroosmosis in the rectangular microchannel are performed with finite element method after simplifying the coupled governing equations. The numerical results indicate that the solution temperature in a PDMS made microchannel is significantly higher than that in a glass made microchannel and the buffer temperature increases as the aspect ratio (W/H) increases.
Numerical Study on the Axial Flow Force of a Spool Valve
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
L. Wang and Y. Chen and Y. Lu,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 177-183,
November 1998
view abstract
This paper studied the fluid flow in a spool valve numerically using the k-ε two- equation model of turbulent flow, while experimental results were drawn out by means of particles image velocimetry technology. The numerical result is compared with the experimental one to verify the viability of the numerical method. Based on many times calculations, it is found that the spool valve's steady axial flow force can be reduced considerably just by modifying the relative position of the oil ports and buckets.
Offshore Hydraulics
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
M. Grahl-Madsen,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 329-344,
view abstract
No abstract available
Oil stiction in hydraulic valves – an experimental investigation
Fluid Power and Motion Control 2008
ISBN: ISBN: 978-0-86197-150-3,
M. Resch and R. Scheidl,
2008,
pp. 457-468,
September 2008
view abstract
Oil stiction arises whenever two surfaces form a narrow gap filled with oil. For fast switching hydraulic valves with flat anchor solenoids this stiction force may degrade the valve opening response significantly.
In spite of a vast literature on oil sticking - about 100 papers from different engineering fields have been studied - an adequate model of the stiction process in hydraulic valves is missing. Some research work has been done in the area of compressor valves where oil stiction often reduces reliability. Most of the literature found concerns basic research addressing adhesion, surface tension, fingering, etc.. The authors’ research intends to combine and extend the existing knowledge to get an appropriate model of the stiction process in hydraulic valves. The calculation of the maximum stiction force and some design rules to avoid the stiction force are the main final objectives.
To understand the fundamentals and to check theories a test rig has been built. This test rig can generate the very fast separation of two parallel plates by a servo-valve controlled short stroke hydraulic cylinder and is equipped with sensors for the gap size, the separation speed, and the stiction force. First stiction measurements between parallel plates were done. For small gaps the measured stiction force curves correspond to those computed from the Reynold’s equation, known as Stefan’s force in literature. For larger gaps, however, additional effects, like fluid inertia, become significant and need a refined computational model.
Oily High Bulk Modulus Fluid of New Concept for Hydraulic Fluid
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
T. Tsubouchi and J. Shinoda,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 367-378,
März 2010
view abstract
Hydraulic fluids of new concept, oily high bulk modulus fluids, have been developed as a new approach to improve the performance of a hydraulic servo system. Since the new fluids have high bulk modulus as high as that of water, the improvement of response time delay and compression energy loss owing to volumetric shrinkage by pressure can be expected. Basic pressure response experiment has verified the improvement of response time by 18 % compared to mineral oil as in theory, and new possibilities of applications are promising. The fluids are environment friendly as well because most of them are biodegradable.
On 3D Viscid Periodic Wave Propagation in Hydraulic Systems
Power Transmission and Motion Control - PTMC 2006
R. Scheidl and B. Manhartsgruber,
2006,
pp. 109-120,
September 2006
view abstract
It is well known that periodic waves in a straight pipe exhibit small dynamic boundary layers. A nice explanation of the characteristics of this boundary layer has been given by Gittler, Kluwick, and Brummayer using singular perturbation techniques and asymptotic expansions. They split the whole flow into a compressible bulk flow without any friction (omitting viscosity) which characterises the flow in nearly the whole cross section and a dynamic boundary layer which is strongly effected by viscosity. Their results tell that the effect of the boundary layer on the bulk flow in the centre is given by radial velocity components which work similarly to flexible walls which hinder the flow of an inviscid fluid in its interior if their tangent plane is not parallel to the main flow direction. On the other hand, the usual derivation of the transmission line equations does neglect any radial velocity component but uses the shear stresses at the boundary layer. Yet, the results of both approaches are nearly identical. This raises the question of the true physical background of the effect of the boundary layer.
ON A FRF BASED EXPERIMENTAL SUB STRUCTURING TECHNIQUE FOR LINEAR VIBRATING SYSTEMS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
A.O. Andrisano and G. Bonori and G. Catellani and F. Pellicano,
2002, Juli 2002
view abstract
In this paper the dynamic behavior of an assembled structure is synthesized by means of Frequency Response
Functions (FRF) of the sub-structures. The synthesized FRFs of the assembled structure are compared with actual FRFs
data estimated by performing test on the assembled structure. The FRFs of the sub-structures have been obtained by of
impact dynamic tests; experimental data are filtered to eliminate Gaussian pollution. Fitting algorithms have been used on FRFs in order to estimate modal parameters of sub-structures; the fitting process allows for filtering out nonlinearities of the measured FRFs. The symmetry of measured FRF matrix is imposed in order to obtain a data set, which is coherent with linear structural models. Vibration tests have been performed using standard accelerometers, which are not able to measure rotational degrees of freedom; in order to circumvent this problem a special measurement procedure is employed. The present experimental FRF based approach is compared with the numerical data obtained by a FEM study.
On Cavitation Characteristics of the Shapes in Water Hydraulic Seat Valves
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
T. Leino and K. T. Koskinen and M. Vilenius,
2007,
volume 2,
pp. 61-73,
Mai 2007
view abstract
The performance of the water hydraulic seat valve with the several different shapes in the cavitating flow conditions has been investigated in this research project. The previous experiments and simulations made with the method of computational fluid dynamics are treated in the light of the recent findings in the simulations. The cavitation
modelling is applied to the case where the vapour clouds are seen in the experiments.
Essential facts, that have to be borne in mind in the simulation of the seat valve, are proposed. The numerical model does not give realistic result for the pressure
distribution in the orifice shape modelled with the absolutely sharp edge. The influence of the sharpness of the edge in the experimental valve is also investigated. According
the limited set of measurements, the sharpness does not seem to have such a radical impact on the cavitation production that would be presupposed bases on the simulation.
ON CAVITATION IN FLUID POWER
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
T. Koivula,
2000,
pp. 371-382,
September 2000
view abstract
Cavitation consists of evaporation and condensation of a liquid. Cavitation normally occurs when liquid at constant
temperature is subjected to vapour pressure. In fluid power applications the evaporation pressure is
reached when flow velocity is increased sufficiently. The occurrence of cavitation in fluid power is mostly detrimental.
One of the devastating consequences of cavitation is the mechanical degradation of a solid material
(cavitation erosion). Because cavitation is mostly harmful to the system it is to be avoided as far as possible.
When actions for preventing cavitation are considered, it is essential to recognise the existence of cavitation and
location of cavitation inception point. Direct detection of cavitation is often impossible due to the complicated
constructions of fluid power components. Due to restrictions of direct detection of cavities, various indirect
methods can be used.
In this paper, cavitation phenomenon is explained and effects of cavitation on the system are dealt with. Cavitation
erosion mechanisms are described and parameters affecting the degree of formed cavitation erosion are
discussed. Various methods for cavitation detection are presented.
ONE-DEGREE-OF-FREEDOM MODEL FOR TORQUE-MOTOR DYNAMICS
E. Urata,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 35-42,
August 2004
view abstract
This paper shows a simplified mathematical model for a torque-motor used in servovalves. The torque-motor treated
in this paper is a commonly used prototype, in which an armature and flapper assembly is supported by a flexure tube.
Combining mathematical expressions for mechanical and electromagnetic elements, transfer functions between variables
are given. To represent the mechanical structure, a one-degree-of-freedom vibration system is assumed. This assumption simplifies the model, although restricts the frequency range in which the model can be applied. The analysis
includes the influence of eddy currents in the yokes and armature. A first-order delay relating coil current to armature
torque is used to represent the influence. Experiments verified that the presented mathematical model is valid up to the
fundamental natural frequency of the vibration system.
One pneumatic line based inchworm-like micro robot for half-inch pipe inspection
J. Lim and H. Park and J. An et al.,
In Mechatronics,
2008,
volume 18,
pp. 315-322,
September 2008
view abstract
By using only one pneumatic line, an inchworm-like micro robot for pipe inspection is invented. Based on drilling different micro holes among the three chambers, the timing of the airflow can be controlled within the chambers. The rear clamp, the elongation module, and the front clamp work sequentially as the air flows into each chamber. It enables the robot not only to generate inchworm-like locomotion, but also to allow for a significant reduction in both the stiffness of pneumatic lines and the friction force caused by one pneumatic line. In addition, it is possible to fabricate a micro robot with diameter of 10 mm since it does not need extra pneumatic lines to connect chambers. In order to operate the robot efficiently, the stroke corresponding to the supplied pressure is theoretically analysed with various sizes of holes between the rear clamp and the elongation module and it is compared to the stroke of the experimental results. Based on these results, maximum velocity was obtained by tuning the air insufflation time under the in-pipe conditions. Finally, the adoptability of the robot was tested under a variation of pipe diameters.
On Fluid Power Control by Switching Techniques
Proceedings Joint Hungarian-British Int. Mechatronics Conference, 21.-23. Sept. 1994, Budapest
ISBN: 1 85312 367 6,
A. S. A. El-Lail and R. Scheidl and D. Schindler,
Computational Mechanics Publications, Southampton, Boston ,
ed. M. Acar, J. Makra, E. Penney,
1994,
pp. 551-556,
September 1994
view abstract
Switching techniques are state of the art in case of electric drives but are not used so far for hydraulic drives to achieve high efficiency. In this paper a basic principle to apply this method to hydraulic drives and some investigations to assess its practical feasability and performance are presented. Such a control method requires basically a switching valve, a resonator-pipe, and the hydraulic actuator which might be a hydraulic cylinder or a hydraulic motor. Such a system ideally fulfilles the basic requirements if no resistance occurs in the resonator-pipe and in the valve and if furthermore some resonance condition is preserved by a properly adjusted switching frequency. In case of friction, energy losses cannot be avoided. The system is investigated by an analytical model based on one-dimensional, laminar, compressible fluid-flow. The theoretical results are compared wich experiments.
On-line condition monitoring of a radial LSHT motor in a pulp washer application
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
T. Huvila and E. Mäkinen,
2007,
pp. 15-25,
September 2007
view abstract
In this paper a case study of condition monitoring of a hydraulic motor is presented. Studied motors are low speed, high torque (LSHT) hydraulic motors that are used at a pulp mill to drive pulp washers.
An index number for estimating the condition of the motor at different temperatures and pressure conditions is introduced. The index is based on measured leakage flow, pressures and temperatures at a given point and comparing the calculated values with a known reference point.
The thermodynamic monitoring method is well suited for this kind of measurement since it doesn’t significantly affect the machine’s normal operation. This paper will take a look at the general principles of realising such measurements and their feasibility in this research.
On-Line Identification of Deformation Resistance and Mill Stretch Coefficient for Cold Rolling Mills
Proceedings Metal 98, Ostrava
K. Aistleitner and A. Kugi and B. Manhartsgruber,
1998,
pp. 109-116,
Mai 1998
view abstract
The increasing requirements of thickness tolerances of cold rolled products demand the use of advanced algorithms for on-line identifictain of process - parameters and automatic adaption of controller parameters at the controller level. This paper should point out a solution how to identify the deformation resistance and the mill stretch coefficient during the rolling process, which define the gain factor of the control loops for the thickness control. The solution presented is not only based on theoretical investigations, but als measured data sets of a cold tandem mill are used to verify the algorithms and show the feasibility of the proposed design. The developed algorithm is part of pre-investigations for advanced thickness control systems of VAI's automation products for cold rolling mills.
On-Off Control With Specified Fuel Usage
William Singhose and Tarunraj Singh and Warren Seering,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 206-212,
Juni 1999
view abstract
A method for generating on-off command profiles for flexible systems is presented. The command profiles move a system without residual vibration while using a specified amount of actuator fuel. Robustness to modeling errors can be incorporated into the design of the command signals. Techniques are presented that facilitate implementation and indicate prudent choices for the amount of fuel to be used. The method is compared to other command generation techniques that balance fuel usage and slew time.
On Soft Sensing for Instantaneous Flow in Hydraulic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
Y. Wang and T. Liu and W. Jiang and H. Sun,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 625-627,
April 2005
view abstract
The measurement of high frequency dynamical flow in dynamical test of Electro-hydraulic proportional valve and Electro-hydraulic servo valve is very difficult. In present, the soft sensing theory is utilized for measuring the high frequency dynamical flow. Basing on the Laminar flow theory of fluid flow, the mathematic model of instantaneous flow in dynamic flow course is given. During the measurement, the differential pressure between two cross-cut sections along the pipe and the temperature of the fluid are measured online at first. Then the instantaneous flow at any time can be calculated and output by computer through special program, which can easily be implemented on a personal computer and takes less memory and computational time. In this way, the developed soft sensing flow meter is a marked advantage over traditional pressure-type flow meter.
On stability and dynamic characteristics of hydraulic drives with distributed vales
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
M. Linjama and M. Huova and M. Vilenius,
2007,
pp. 297-313,
September 2007
view abstract
The basic principle of distributed valves is to replace single-spool valve with several independent valves. Systems with distributed valves can save energy and have potential for better controllability but they are more difficult to control because of increased degrees of freedom. This paper presents different distributed valve configurations and develops general non-linear and linearised state-space models for them. The models developed cover all different valve configurations and control strategies as well as different feedbacks. Characteristics of some P-type position control strategies are analysed and it is shown that controllability of differential connection is equal or even better than controllability of traditional inflow-outflow control.
On Switching Techniques for Hydraulic Drive Systems
A. A. S. El-Lail and R. Scheidl,
In ZAMM,
1994,
volume 74,
pp. T 358-T 361,
view abstract
A hydraulic system comprising a long pipe, in which wave propagation takes splace, a hydraulic cylinder, loaded by a constant force at its end, and a switching valve, which connects the pipe entrance port periodically with the low- and high-pressure line, is investigated with respect to its feasibility to act as a switching converter. Energy efficiency and low fluctuation of the motion of the piston are the criteria with respect to which the role of several system parameters is evaluated.
On the Application of an Industrial Motion Controller to a Pneumatic Positioning System
Fluid Power Systems and Technology 1998 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791815939,
N. Brook and B. W. Surgenor,
ASME,
ed. S. S. Nair and S. I. Mistry,
1998,
volume 5,
pp. 207-220,
November 1998
view abstract
This paper documents experience with the application of an industrial motion controller, originally intended for an electric servomotor positioning system, to a pneumatic positioning system. The pneumatic system consisted of a rodless cylinder connected to a proportional servovalve with a
command signal generated by the motion controller. A linear analog potentiometer provided position feedback to the controller. The payload was 5 kg with a stroke of 0.6 m. Results demonstrate that respectable performance can be achieved, although the PID tuning technique normally implemented with the motion controller could not be used. An achievable motion trajectory is identified, and an appropriate PID tuning techniques is presented.
On the Bulk Modulus of Hydraulic Fluids in the Presence of Dissolved Gas
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
H. Stern,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 113-123,
November 1997
view abstract
This paper documents the initial phase in a program to record and evaluate the effects of air dissolved in hydraulic fluids. Some quantity of dissolved air is a fact of life in most hydraulic systems, yet physical properties of hydraulic fluids are normally reported for the de-aerated or degassed base fluid. While dissolved air effects are generally reported to be "small" or "negligible", very little quantitative information has been published to document the actual values.
The bulk modulus of fluids is one of the important parameters of all dynamic control systems and plays an important role in the design and life of positive displacement pumps and motors for high pressure service.
It was therefore chosen as the initial object of this study and is the basis for the design and construction of the test equipment referred to in this paper.
Initial tests, by no means conclusive, at this stage, seem to verify the assumption of small deviations, but definitely suggest that measurable differences in the trend of bulk modulus with respect to pressure do exist for a aerated SAE1O, automatic transmission, and vegetable base hydraulic fluids.
ON THE CONTROL OF JOINT INTEGRATED SERVO ACTUATORS FOR MOBILE HANDLING AND ROBOTIC APPLICATIONS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
J. Grabbel,
2000,
pp. 449-465,
September 2000
view abstract
This paper presents a new joint integrated rotary servo actuator design for heavy load mobile manipulators and
robots. The current state of actuator technology in mobile machines is discussed briefly. A new solution for a
pump controlled joint integrated actuator is proposed. For end effector axes this design is ideal for electrical
power distribution, known as power by wire. Two different control strategies are presented and discussed in its
advantages and disadvantages.
ON THE DEVELOPMENT OF A REAL-TIME SIMULATOR ENGINE FOR A HYDRAULIC FORESTRY MACHINE
E. Papadopoulos and Y. Gonthier,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 55-65,
April 2002
view abstract
This work focuses on the development of a real-time training simulator engine for a forestry machine. The rigid
body dynamics of the machine’s manipulator is integrated with electrohydraulic actuator dynamics and joint controllers.
System numerical stiffness introduced by the closing valves, high order hydraulic dynamics, and simulator implementation
using an interpreted language were identified as the prime reasons for slowing down the integration. Successive
models of lower complexity and switching between models for the open and closed phases of the valves are proposed
aiming to achieve a satisfactory simulator engine that can run in real-time. Simulation results demonstrate very good
prediction of an actual machine behaviour with execution speeds improved by a factor of 35.
On the Dynamic Behavior of Servo-Hydraulic Drives
R. Scheidl and B. Manhartsgruber,
In Nonlinear Dynamics,
1998,
volume 17,
pp. 247-268,
Oktober 1998
view abstract
A servo-hydraulic drive for position control with a flapper-nozzle type servo-valve is described by a 10th-order, non-linear system of ODEs. This system is partially singularly perturbed. The perturbation stems from the compressibility of the hydraulic fluid and the fast dynamics of some sub-systems of the valve. Center manifold theory in the version due to Fenichel is used to study the behavior of the drive system in the case of periodic motions. The insufficient differentiability properties of the system prevent the direct application of Fenichel's theorems. Thus, phase space is decomposed into sub-spaces each with sufficient differentiability properties. There, limit sets of the system can be given as the solution of the reduced problem. Approximate analytical solutions are derived for that. At the boundaries of adjacent sub-spaces transition layers occur which connect these limit set trajectories of adjacent sup-spaces. The order of magnitude of these transition layers is estimated by asymptotic expansions. Further, a comment is given on the stability properties. Stability is strongly affected by the small perturbation parameters and is most critical in the resting position of the drive. Theoretical results are compared with numerical computations and experiments.
On the Limitations of Force Tracking Control for Hydraulic Servosystems
Andrew Alleyne and Rui Liu,
In Journal of Dynamic Systems, Measurement, and Control,
1999,
volume 121,
pp. 184-190,
Juni 1999
view abstract
This paper presents analysis of a particular force tracking control problem for rectilinear hydraulic actuators governed by a servovalve. It presents no new theory, but rather uses a revealing model reduction insight coupled with Classical analysis to explain a physical phenomenon. As such, this work is an attempt to explain why a seemingly innocuous problem is more subtle than initially believed. A motivation for this problem is given along with prior attempts at a simple solution. It is shown that simple controller solutions are quite adequate for other types of control objectives such as force regulation or position tracking. However, most simple solution methods are shown to be inadequate for force tracking due to fundamental limitations of the problem formulation. Due to an inherent feedback mechanism, the poles of the plant being forced by the hydraulic actuator become zeros of the open loop force transfer function. Therefore, more advanced control algorithms are shown to be a necessity rather than a luxury.
On the Observability of Pressure in a Pneumatic Servo Actuator
Jianhui Wu and Michael Goldfarb and Eric Barth,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 921-924,
Dezember 2004
view abstract
Pneumatic servo actuators are characterized by highly nonlinear dynamics from spool valve command to cylinder pressure and, as such, are well suited to the use of nonlinear control methods requiring measurement of the full state, such as sliding mode control. This paper investigates the possibility of eliminating the pressure measurement required for nonlinear control in lieu of a nonlinear pressure observer, based on measurement of the output motion. A nonlinear observability analysis is conducted that demonstrates that such a system loses local observability in several regions of the state space, thus rendering the system unobservable.
On the Passivity of a Galerkin Finite Element Model For Transient Flow in Hydraulic Pipelines
B. Manhartsgruber,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Eng.,
2006,
volume 220,
pp. 223-237,
view abstract
The Galerkin finite method for the simulation of transient, laminar flow in hydraulic pipelines with an interlacing grid has gained considerable popularity because of the relatively good accuracy achieved with a moderate model order. However, the implementation used in a number of software packages has recently been shown not to guarantee model passivity. This paper reviews the concept of using an interlacing grid. Two modifications of the previously published interlacing grid method are proposed and the resulting model is shown to fulfil the passivity requirement in an example where the previously published method fails. The new model also improves the approximation error in terms of the deviation of the frequency response from the theoretical frequency response given by the transcendental transfer functions of the well-known 'frequency-dependent friction' model. This improvement is bought at the expense of a slight increase in model order due to additional nodal values for the friction model at the boundary nodes. Furthermore, the new model is given in the form of a descriptor system in order to maintain the sparse structure of the system matrices.
On The Pressure Peak Minimization in Digital Hydraulics
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1759-4,
A. Laamanen and M. Linjama and M. Vilenius,
2007,
volume 2,
pp. 107-122,
Mai 2007
view abstract
Non-ideal on/off valves may cause coincidentally pressure peaks in digital hydraulics.
The risk of pressure peaks depends on the coding scheme of the digital hydraulic valve system. Traditional Pulse Code Modulation (PCM) control based on the binary coding
has high risk for pressure peaks whereas in Pulse Number Modulation (PNM) control pressure peaks does not occur at all. However, PNM is not yet a solution for pressure peak problem in digital hydraulics due to some technical issues. Instead, Fibonacci coding is a compromise between the above systems and it can ease pressure peak problem in digital hydraulics. Together with coding, controller has also an influence on
pressure peaks. Cost function based controller can take into account the risk of pressure peaks in different state transitions and the bad state transitions can be avoided. In this study, a cost function for pressure peak minimization is utilized in a binary and Fibonacci coded valve system based on Separate Meter-In and Separate Meter-out (SMISMO) control. Suitability of different coding schemes is evaluated and the effects of controller parameters on pressure peaks are experimentally studied.
On the Stability and Performance of Two-Stage Hydraulic Servovalves
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
H. Wright and A. Alleyne and R. Lui,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 215-222,
November 1997
view abstract
In this work, a System Dynamics viewpoint is used to examine the stability and performance of a class of hydraulic devices. These devices use hydraulic amplification to command motion of large objects using relatively low level signals. A model is constructed and used for both analysis and simulation of system performance. The analysis is from a linear Classical Controls perspective and is found to be sufficient despite the nonlinear nature of the systems. The analysis is used to consider design changes to the valve components and their resulting effects. Even though the subsystems consist of stable individual components, their interconnection can lead to undesirable performance, or even instability, if the individual dynamics are improperly matched.
On the Transient of Pressure Waves in Ducts for Systems Operating in Industrial Automation
Arcangelo Messina and Giosué Rollo,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
März 2010
view abstract
Within the frame of industrial automation, the mechanical power related to pneumatic actuator systems involves air flows along with mechanical component, such as valves, connecting tubes, cylinder chambers and possible linkages in order to finally actuate a specific objective. Gas dynamic of the air flowing into connecting ducts plays a fundamental role in the description of the global dynamic phenomena of these systems. Several studies deal with the dynamics of such pneumatic systems but through streamlined analysis where the influence of pressure-waves propagating in ducts is neglected or poorly described. The related models are even more complex when finite volumes are placed at the ends of connecting lines. In this paper, two different mathematical models describing transient pressure-waves propagating through lines closed by finite volumes are presented. The investigation regards pressure and velocity ranges normally operating in industrial pneumatic systems. Besides the value of new system modeling of different complexity, these models are compared from an analytical and numerical point of view; advantages, disadvantages, weakness, abilities, and inabilities are highlighted and, finally, the relevant analysis is corroborated through experimental validations of wave propagating pressure at fixed positions of ducts. This study results both in the presentation of models of practical interest, as well as in an attempt to provide an elucidation on the need to resort to an accurate model rather than a streamlined one with respect to the geometric and/or operative characteristics of industrial pneumatic systems.
On the Use of Block Backward Differentiation Formula Methods for the Simulation of Fluid Power Systems
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 1999
B. Manhartsgruber,
Professional Engineering Publishing,
ed. Burrows and Edge,
1999, September 1999
view abstract
This paper deals with the use of a DAE solver for the simulation of fluid power circuit models. The block backward differentiation formula (BBDF) method is compared to the solvers implemented in MATLAB and SIMULINK. Two benchmark problems are used for this comparison. The BBDF method gives reliable results while reducing the computation time significantly.
On Ultrasonic Detecting-Based Dynamic Flow Measurement Technology
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
J. Wanlu and S. Hongmei and G. Ming,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 767-771,
April 2005
view abstract
Several methods of flow measurement based on ultrasonic detecting, including the velocity difference method, Doppler method and correlation method, are summed up. Their principles are systemically expatiated. The characteristics of ultrasonic flowmeters are summarized. Ultrasonic measurement methods are expected to solve the problem of dynamic flow measurement.
On Using Unstable Electrohydraulic Valves for Control
Kailash Krishnaswamy and Perry Y. Li,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 183-190,
März 2002
view abstract
High bandwidth, high flow rate electrohydraulic valves typically have two or more stages. Most multi-stage valves are expensive, require meticulously clean fluid, and introduce higher order dynamics. On the other hand, single-stage spool valves are cheaper and more reliable. However, a majority of them are not suitable for high bandwidth, high flow rate applications due to limitations of the electromechanical/solenoid spool-stroking actuators. In this paper, we investigate the feasibility of reducing this limitation by exploiting the transient flow forces in the valve so as to achieve spool dynamics that are intrinsically open-loop unstable. While conventional valves are designed to be open-loop stable, the unstable valve design has to be stabilized via closed-loop feedback. Simulation case studies are conducted to examine the potential dynamic and energetic advantages that an unstable valve may offer. These studies indicate that unstable valves provide faster response than the stable counterparts when stroking forces are limited. Moreover, unstable valves tend to require less positive power and energy to operate.
OPEN CIRCUIT SOLUTION FOR PUMP CONTROLLED ACTUATORS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
K. Heybroek and J. Larsson and J.-O. Palmberg,
2006,
volume 1,
pp. 27-40,
Juni 2006
view abstract
Today’s mobile machines most often contain hydraulic valve controlled actuator loads in an open loop circuit. For the
purpose of saving energy, the constant pressure pumps have in the past often been replaced by load-sensing pumps and
load-sensing valves. In mobile applications, these load-sensing solutions have significantly reduced the energy
consumption. However, stricter environmental demands and rapidly increasing fuel costs require an even lower
consumption. By analyzing a typical working cycle of a construction machine, the possibility of energy recovery has
been identified. The analysis also confirms the importance of minimizing the metering losses. In a load-sensing valve
solution, these losses arise as a result of the unequal drive pressure levels. By instead adopting a displacement
controlled regenerative solution, a significantly higher level of efficiency can be obtained. A comparison between an
open and a closed circuit solution shows that the open circuit solution has a great potential and is interesting for
further research. This regenerative open circuit eliminates the metering losses of conventional valves and replaces each
actuator valve/supply system with a variable displacement pump/motor. This pump/motor can also be used to recover
the potential and kinetic energy either to the power train or directly to other hydraulic functions. The hydraulic system
is designed to actuate asymmetrical cylinders. Concepts are evaluated where the cylinder chambers are connected to
each other in order to reach a higher pressure level and thus higher regeneration efficiency. To achieve stable behavior
of this circuit an accurate control is required. The controller handles the synchronization of switching between different
modes and is also used to suppress oscillations. In order to measure the potential energy recovery an efficiency model
is used together with the simulated open circuit solution.
Operating Strategies and Valve Requirements for Digital Pump/Motors
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
K. J. Merrill and J. H. Lumkes,
2010,
volume 1,
pp. 249-258,
Juni 2010
view abstract
There is a desire to improve the efficiency of fluid power systems. At the heart of a fluid power system is the
pump/motor. Current state-of-the-art variable displacement pump/motors have fairly good efficiency when operating at
maximum displacement. However, when operating at lower displacements the efficiency dramatically decreases. The
advantages and challenges of a fundamentally new digital pump/motor are explored in this paper. The digital
pump/motor utilizes two high-speed on/off valves at each pumping piston instead of a valve plate for porting the fluid.
A simulation study is conducted to obtain insight into the advantages and challenges of a digital pump/motor. The
sensitivity to the dead volume in the piston chamber is compared between a valve plate pump and a digital pump.
There are different operating strategies to accomplish variable flow with a digital pump/motor. The difference in flow ripple and efficiency is compared between the different operating strategies.
Operator Efficiency Improvements From Novel Human-Machine Interfaces
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
M. Elton and W. Book,
2010,
volume 1,
pp. 315-322,
Juni 2010
view abstract
State of the art human-machine interfaces for multi-DOF mobile hydraulic machines are non-intuitive and require long
periods of training and experience for operators to perfect control of the machine. This paper explores using a novel
human-machine interface to control a simulated 5-ton mini-excavator. After a brief discussion of the simulation and the tests performed, it reports on improvements in operator productivity and efficiency of the novel interface over the
standard interface. A new measure of fuel efficiency in terms of fuel per task is explained, and the test results show that
a more intuitive input device increases fuel efficiency.
OPTICALLY POWERED HYDRAULIC PILOT VALVE USING PIEZOELECTRIC MULTILAYER ACTUATOR
J. Lim and P. R. Jackson and Q. Yang and B. E. Jones,
In International Journal of Fluid Power,
2001,
volume 2,
pp. 15-21,
November 2001
view abstract
A normally-closed 2/2 hydraulic pilot valve has been developed for a power- by-light system which is being applied
in aerospace fuelling systems and oil-well applications. This system offers unique advantages such as good immunity
from electromagnetic interference, intrinsic safety, and low attenuation for long distance.
The valve employs a piezoelectric multilayer bender actuator (Pz29) with an elastomer blocking plate and a nozzle
as the valve mechanism. The valve system is operated by 86 mW optical power which is transmitted via a multimode
optical fibre (core diameter 62.5 μm) from a laser diode light source. The optical power is converted to electrical power
by a photovoltaic cell, to drive the pilot valve, which requires, 8 mW electrical power to operate. The valve output flowrate of 28 cm3/s has been achieved at an operating pressure of 1000 kPa, which is adequate for the applications. However,
the maximum operating pressure up to 2000 kPa has already been tested. For the valve dynamic response, 18 ms average opening time and 1.5 seconds controllable smooth shut-off time have been observed. There was no valve operation
failure during vibration testing up to 196 m/s2. The pilot valve is now used to operate an aircraft refuelling valve
system that provides aviation fuel flow-rate up to 680 l/min. It can also be used for other hazardous environments and
noisy applications.
Optimal Control for Bouncing Suppression of CNG Injectors
D. Dyntar and L. Guzzella,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 47-53,
März 2004
view abstract
This paper describes the model-based design and the experimental validation of a control system which suppresses the bouncing behavior of Compressed Natural Gas (CNG) fuel injectors. First a detailed model of the system is developed, including temperature and supply-voltage variation effects. Using an optical position sensor, this model is experimentally validated in a second step. Based on this model a feed-forward controller is developed and tested which minimizes the bouncing energy of the system. Since in series applications position sensing would be too expensive to use, an observer-based iterative control algorithm is derived which uses coil current measurements instead of the position information to asymptotically suppress bouncing.
Optimal Control of a Parallel Hydraulic Hybrid Vehicle Powertrain
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-14-9,
R. G. Ertel and K. A. Stelson,
2010,
volume 1,
pp. 69-85,
Juni 2010
view abstract
The parallel Hydraulic Hybrid Vehicle (HHV) powertrain is quickly becoming a viable option among large (class 7-10)
vehicles. This is due to its potentially vast improvements in fuel economy over non-hybrid powertrains. Optimal control
of the parallel HHV powertrain is critical to overall vehicle performance and is largely responsible for gains in
efficiency. It is desirable to know how to best operate the powertrain to achieve maximum efficiency during driving
intervals when vehicle speed is unspecified, except at boundary points. In this paper, a state-space model of the parallel HHV powertrain is derived in the energy domain using a classical Lagrangian approach. Optimality conditions are
extracted using techniques from the calculus of variations, and from modern optimal control theory. A gradient descent
based optimal control algorithm is developed and applied to a number of different problems. The results offer valuable
insight into efficient operation of the parallel HHV powertrain.
OPTIMAL CONTROL OF HYDRAULICALLY ACTUATED FLEXIBLE MULTIBODY SYSTEMS
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
M. Ebbesen and T. O. Andersen and M. R. Hansen,
2006, August 2006
view abstract
The paper is on automated tool point path and velocity control of a loader crane. A two step approach is used that
combines a direct computation of the optimal cylinder velocities with a general procedure that includes the different
saturation phenomena encountered in a hydraulically actuated mobile machine. The two step procedure is envoked at
each sampling instant during operation and returns the desired valve control signals. The first step of the procedure
involves a direct computation of the optimal cylinder velocities for all possible combinations of active and non active
cylinders. Among the configurations that may produce the exact velocity reference, the one requiring the least hydraulic
power is chosen. Some simulation examples of the proposed procedure are shown and dynamic simulation based on the
possibility of varying the speed of the electrohydraulic valve are carried out including the flexibility of the hydraulic
fluid and the mechanical structure, respectively.
Optimal Design of a High-Speed On/off Valve for a Hydraulic Hybrid Vehicle Application
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
M. Rannow and P. Li and T. Chase and H. Tu and M. Wang,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 523-536,
März 2010
view abstract
Control of hydraulic systems using high-speed on/off valves has been proposed as a way to avoid the inefficiency associated with throttling valves. However, on/off control has sources of energy loss that must be considered when designing a system, such as transition throttling, full-open throttling, compressibility, and leakage. A self-spinning rotary on/off valve achieving high switching frequencies with low actuation power has been developed. However, the design of this valve contains numerous tradeoffs that must be balanced to produce the most efficient system. This paper outlines energy loss equations and design constraint equations that are needed to apply optimization techniques to the valve design. The results of this optimization are presented for a Virtually Variable Displacement Pump, and a Virtually Variable Displacement Pump/motor, which is used as the wheel motor of a hydraulic hybrid vehicle.
OPTIMAL RESPONSE OF PRESSURE REDUCERS AND STABILITY INFLUENCES OF THE DOWNSTREAM LINE DYNAMICS
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
G. Favennec and M. Alirand and M. Lebrun,
2002, Juli 2002
view abstract
Stability analysis of pressure reducing valves is carried out using standard results of root loci and Routh-Hurvitz
criterion. This gives a limit value for the flow gain. However this flow gain is not optimal and leads to possible
oscillations. Using a pole placement technique the flow gain is calculated in order to obtain an optimal response.
Another aspect is the influence of the downstream pipeline system upon the valve. Usually pressure reducers are
connected to the controlled volume using a pipe. The downstream line dynamics can consequently modify the dynamic
behaviour of the system. A linear analysis shows that the valve dynamics can be decoupled from the line dynamics. A
special test rig is designed to carry out experiments on a typical reducing valve of an automatic gearbox hydraulic
circuit. Experiments and simulation were in good agreements and showed that the oscillations downstream the valve
came from the line dynamics and not from the reducing valve dynamics.
Optimisation of a Hybrid Diesel-Hydraulic Automotive Powertrain using ADVISOR, Matlab and Simulink.
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
P. L. Matheson and J. S. STECKI,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 165-173,
November 2003
view abstract
The Hydraulic Hybrid Vehicle obtains energy for propulsion from two different sources, the Internal Combustion Engine (ICE) and a hydraulic pump/motor. Braking torque is supplied by operating the unit as a pump, and thus storing the otherwise lost kinetic energy of the slowing vehicle. During acceleration the unit is operated as a motor, using the stored energy to assist propulsion. A model of the systems was developed in the Matlab/Simulink environment then implemented into the automotive simulator ADVISOR. This paper outlines the procedures used for optimisation studies within ADVISOR, to find the ideal combination of system parameters, e.g., pump/motor displacement, accumulator size and pressures, that yield the best results for fuel consumption for a standard urban drive cycle.
Optimisation of Piezo Common Rail Injector Robustness with Simulations
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
F. Borchsenius and X. Gebhardt,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 447-458,
März 2010
view abstract
Piezo common rail injectors are state-of-the art components in diesel engines [1]. In order to fulfill the stringent emission requirements very small injection quantity deviations are acceptable. Since the injection quantity depends on a large number of parameters with individual tolerances this aim can only be achieved with robust components in combination with adaptive control functions. Robustness means smallest possible sensitivity to non-controllable parameters (e.g. production tolerances or wear). In order to optimize the robustness 11 parameters with significant influence on the injection characteristics have been identified. These parameters were used for numerical optimisation of the injector characteristics using a validated simulation model. The simulation model has been set up with the simulation program HSSIM which is a new development based on HYSIM [2]. HSSIM supports graphical modelling and is very fast compared to other commercial simulation tools. Since the target function of the optimisation is highly nonlinear and shows a lot of local optimum solutions evolutionary algorithms have been used [3]. Such optimisation algorithms require many simulations (about 30000), so simulation time is an important factor. The optimisation result is a set of parameters that show a smoother injection characteristic that is less sensitive to parameter deviations.
OPTIMISATION OF THE PROPORTIONAL SOLENOIDS FOR ELECTROHYDRAULIC CONTROL SYSTEMS
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
V. Muraru and C. Muraru,
2000,
pp. 157-166,
September 2000
view abstract
The paper contains an analysis of a proportional solenoid widely used in hydraulic control systems. The analysis was
made by a parametric model for the geometry of the solenoid and the current. The main result of the research is the
optimisation of the geometry of the of the solenoid by computing the electromagnetic force on the spool. Using a parametric model we have also study the relation between the electromagnetic force and the gap, the relation between the
electromagnetic force and current, etc. The theoretical results are found in good agreement with the experimental ones.
The main conclusion of the study is the linear relation between the electromagnetic force and the coil current. We have
also checked the relative independence of the force from the current in the case of a small stroke solenoid (so called "force solenoids").
Optimization and Control of a Hydro-Mechanical Transmission based Hybrid Hydraulic Passenger Vehicle
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
P. Y. Li and F. Mensing,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 457-468,
März 2010
view abstract
Hydro-mechanical transmission (HMT) based hybrid hydraulic vehicle architecture is potentially more efficient than other architectures because: 1) it uses the efficient mechanical transmission for partial power transfer, 2) it allows the engine to operate at its most efficient point. The input coupled power split hybrid vehicle being developed is one such example. The increase in degrees of freedom makes design, control and analysis more challenging. In this paper, HMT hybrid vehicle dynamics are derived and decomposed explicitly into decoupled dynamics that relate to vehicle motion and to efficient vehicle operation. A three level hierarchical control and analysis architecture is then introduced that separates the vehicle operation into a drive cycle dependent optimization layer, a non-drive cycle dependent optimization layer, and real time control layer. Exercising this framework indicates that to improve fuel economy, the current vehicle design can benefit from allowing pump/motor lock up, improved pump/motor efficiencies and improved sizing.
Optimization and energy consumption of Electro-Hydraulic Valve Actuation system through valve event timing range
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Herranen, Mika and Huhtala, Kalevi and Vilenius, Matti,
2010,
pp. 433-445,
September 2010
view abstract
Flexible gas exchange valve actuating systems are developed in order to improve the fuel efficiency and lower emissions of the combustion engines.
The aim of this research is to find out power consumption at different performance values of the flexible electro-hydraulic valvetrain system (EHVA). The dynamic demands are high for the electro-hydraulics in this application. That is why it’s challenging task both power consumption and performance of the system point of view. The EHVA system is needed to design according to the highest load and speed situation. Therefore energy consumption and efficiency under normal running conditions may be relatively poor. In this study the energy consumption of certain EHVA system is investigated by means of simulations.
Among others, effect of the cylinder pressure load when exhaust valve is opened, return spring rates, and pressure level control are investigated. Then, actuators of the intake and exhaust valves are optimized in order to find out real energy consumption of the hydraulic system.
This research proved that flexibility of the gas exchange valve actuation has costs at energy consumption side. Also other hydraulic solutions should be applied in order to keep the efficiency higher and the energy consumption at lower level.
Optimization Methods for Valves Design (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
F. Veselý,
2006,
pp. 175-180,
Mai 2006
view abstract
Finding optimum design parameters at projection of hydraulic elements and
systems represents still an open question, very often solved on the basis of experiences and
intuition. In this paper, the optimization method in Amesim environment is used on an
example of the flow control valve. The basic assumption for a successful utilization of the
method mentioned is the availability of a quality and preferably verified model. The paper
describes the optimization procedure used: analysis using the full factor experiment and
seeking the optimum by means of the target function. At the same time, two optimization
parameters, i.e. NLPQL and the genetic algorithms are compared. The results achieved are
compared by measuring of samples.
Optimization of a Fast Switching Valve for Big Flow Rates
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2006
B. Winkler and R. Scheidl,
2006,
pp. 387-399,
September 2006
view abstract
In this paper the optimization of a fast switching valve regarding the critiria rubustness to flow forces and low cost under the constraints of a nominal flow rate of at least 40 l/min and a switching time of about 1ms is presented. Basis for the optimization process was a concept of a switching valve which was derived from three previous designs, all of which had also been prototyped. The main difficulties that have to be overcome are. (i) Spool sticking problems, if tiny land structures are applied, (ii) flow forces which are substantially disturbing the spool motion, (iii) flow oscillations generated by fast switching which create unpleasant noise and pressure pulsation. Problem (i) can be avoided by a specific spool and land design which stabilizes the centered spool position. Flow force reduction can be achieved by shape modification of the spool and the grooves in the sleeve but may conflict with problem (i). The faster the valve the smaller the parasitic hydraulic inductivities of the interior flow channels of the valve have to be. Avoiding such problems gives decisive design constraints in which the optimization problem has to be embedded. Optimization parameters have been spool diameter, spool stroke, and inertia. Flow forces could be reduced considerably by a CFD analysis of different designs of land structures. The resulting design was realized as a new prototype which fulfills the demands on switching time and flow rate. Furthermore, the design is simple which promises a cheap production.
OPTIMIZATION OF HYDRAULIC COMPONENTS USING FLUID-SOLID INTERACTION SIMULATION
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
M. Domagala and E. Lisowski,
2006,
volume 1,
pp. 151-159,
Juni 2006
view abstract
This paper presents an application of Fluid-Solid Interaction simulation (FSI) available in CFD codes in modeling and
optimization of hydraulic components. The possibilities of FSI simulation were shown on example of a direct acting
relief valve. The FSI simulation was used to estimate an influence of flowing fluid on its components as well as to
optimize valve elements geometry. The optimization was aimed at reduction the negative influence of flow forces on
valve flow characteristics. This paper also shows the way that FSI simulation might be used to achieve assumed valve
characteristics. Presented in the work results shows that ANSYS CFX codes and FSI simulation is a useful tool for
modeling and optimization hydraulic components.
Optimization of Hydraulic Systems by Means of Numerical Simulation
2nd International Workshop on Computer Software for Design, Analysis and Control of Fluid Power Systems, Ostrava-Malenovice, Czech Republic
M. Garstenauer and N. Krimbacher and R. Scheidl,
2001, September 2001
view abstract
Simulations are nowadays used to analyse system behaviour investigating the role of Design Parameters for system performance. Furthermore, it is possible to simulate various scenarios and to determine the behaviour of the system at its limits. In this paper several possibilities of system optimization are discussed, exemplified on a novel fast hydraulic position actuator. This actuator can be used, e. g., for driving a large and fast hydraulic switching valve. Deriving a simple analytic model to get the essential Design Parameters and using numerical simulation to optimize a possible realisation are discussed in this paper.
Optimization of Liquid Piston Dynamics for Efficiency and Power Density in a Free Liquid Piston Engine Compressor
Fluid Power and Motion Control 2010
ISBN: ISBN: 978-1-86197-181-4,
Willhite, Joel A. and Barth, Eric J.,
2010,
pp. 461-473,
September 2010
view abstract
An optimization of piston dynamics to achieve performance goals of a High Inertance Free Liquid Piston engine Compressor (HI-FLPC) is presented in this work. The proposed HIFLPC is a compact device that utilizes combustion of hydrocarbon fuel to provide a supply of pressurized air for use in untethered pneumatic systems. The liquid piston of this device is configured such that its geometry is exploited to produce a high inertance, which produces an advantageous (slower) dynamic response as compared to a rigid piston of equal mass. The slower dynamics achieved by the liquid piston allow for reduced valve sizes for the compressor, a direct inject-and-fire engine with no compression stroke, and the
capability of more balanced operation for a single-piston device. These attributes create a more energy-dense device than developed in prior work. A review of the dynamic model of
the HI-FLPC is presented along with experimental model validation of the liquid piston. Simulation studies were conducted to optimize liquid piston dynamic characteristics for overall system performance of an experimental prototype.
Optimization of Parameters of Pseudo-Dynamic Solver for Real-Time Simulation of Fluid Power Circuits
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
R. Åman and H. Handroos,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 495-507,
März 2010
view abstract
The system stiffness approaches infinity as the fluid volume approaches zero causing numerical problems. If fixed step explicit ODE-algorithms are used the stability would easily be lost when integrating pressures in small volumes. The pseudo-dynamic solving method is based on the basic assumption that if the volume in the system to be described is small enough, the pressure can be expressed by a static pressure created in a separate cascade loop by numerical integration. The method is freely applicable regardless of used integration routine. The nominal frequency (time constant) created by the small volume, is not significant in comparison with the dynamics of the whole system. The hydraulic capacitance V/Be of the parts of the circuit whose pressures are solved by pseudo-dynamic method should be at least ten times smaller than that of those parts whose pressures are integrated. Solver parameters: convergence criteria, integrator time step and pseudo-volume are optimized. This paper describes the algorithm in general level
and presents simulation examples. Results obtained are compared.
Optimization of Performance Characteristics of Electropneumatic (Two-Stage) Servo Valve
Igor L. Krivts,
In Journal of Dynamic Systems, Measurement, and Control,
2004,
volume 126,
pp. 416-420,
Juni 2004
view abstract
Servo valve is the key element in electropneumatic servomechanism. In this study, an electropneumatic two-stage servo valves were investigated in order to improve their static and dynamic characteristics. These servo valves consist of a pilot stage and a power stage. The paper discusses three different pilot stages: the jet pipe pilot stage, the supply (side) flapper nozzle pilot stage and the exhaust (side) flapper nozzle pilot stage. The static and dynamic characteristics of the devices were investigated analytically and by computer simulation. For the three pilot stage types it was found that the optimal value of the static and dynamic characteristics could be obtained if the ratio between the effective areas of the supply channel and exhaust port of the pilot stage has a definite value (depending on the pilot stage type).
OPTIMIZATION OF PNEUMATIC POWER SERVO – MECHANISM MADE COMPLETELY FROM POLYMERIC MATERIALS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Kot and E. Lisowski,
2008,
pp. 480-488,
Juli 2008
view abstract
In this paper, we present the problem of designing a new pneumatic power servo-mechanism, made completely from
polymeric materials. This paper focuses also on the tightness of the designer element as well as other issues related
with the durability and efficiency of the component in question.
The object subject to the examination comprises one of the main components of the manipulator, manufactured
completely from plastic materials. One of the most important features of the proposed solution is the elimination of the
undesired reaction of sensors when attempting to disarm the given missile. The application of plastic materials requires
however appropriate design, manufacturing and testing of individual components in a way different from current
components manufactured from metal materials. For this purpose, we exploited computer aided design software,
specialised for such tasks.
OPTIMIZATION OF THE POWER MANAGEMENT STRATEGY FOR A HYDRAULIC HYBRID VEHICLE
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
J. Meyer and K. A. Stelson,
2008,
pp. 371-380,
Juli 2008
view abstract
This paper investigates development of power management strategies for hydraulic hybrid passenger vehicles.
Parallel, series, and power-split architectures are modelled and explored in the Matlab environment using variable
efficiency hydraulic pump/motor models. Results are presented using a rule-based strategy where engine on/off
setpoints for the accumulator and transmission gear shifting were chosen intuitively based on experiences. The
dynamic programming algorithm is then used to rigorously determine the optimal trajectories for engine/hydraulics
power splitting for each of the architectures over urban and highway drive cycles. Results are then compared to
baseline simulation for improvement. Using the given vehicle parameters, the best architecture for both the urban and
highway drive cycles was shown to be parallel, with further work required to improve the power-split configuration.
OPTIMIZATION OF THE WATER HYDRAULIC INTENSIFIER PUMP USED IN THE WATER JET CUTTING SYSTEM OF PAPER MACHINE
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20 – 22, 2000
ISBN: 3-00-006510-5,
M. Hyvönen and K.T. Koskinen and M. J. Vilenius,
2000,
pp. 89-100,
September 2000
view abstract
There are only few water hydraulic high pressure pumps in the market and most of them are very expensive to
buy and maintain. A Finnish company has developed a new type of water hydraulic intensifier pump in which
the control valve is integrated in the plunger. This means faster response in the change situation of the plunger
and more compact size of the pump. The prize of the pump is also reasonable. This paper deals with the optimization
of the intensifier pump using computer simulation and experimental measurements. The aim of the work
is to improve the characteristics and reliability of the pressure intensifier pump. The effect of integrated control
valve characteristics to intensifier pump properties is discussed. The optimum performance is studied via variation
of significant parameters of the intensifier pump.
The other aim of the work is to develop a reliable water jet cutting system for paper machine industry. The
intensifier pump is to be used in the water flow source in the cutting system. One other aim of the work is to
increase the basic knowledge of water hydraulics and to increase the life time of the water hydraulic
components used in water hydraulic systems which has high demands for reliability.
OPTIMIZATION PERFORMANCE OF A MICROFLUID FLOW POWER CONVERTER
F. Lanzetta and P. Désévaux and Y. Bailly,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 5-12,
Dezember 2002
view abstract
This article deals with an application of the endoreversible thermodynamics theory of heat engine applied to microfluid
flow power converters (MFPC). An analogy is demonstrated between thermal and fluid flow efficiencies. Maximum
power output and efficiency at maximum power are established for the device based upon the higher and lower
pressure bounds. The linear and non linear fluid flows are considered with and without fluid friction losses. This paper
provides theoretical limits for designing power flow converter. The best performances are obtained for linear fluid flow
without flow losses.
Optimized pace drive concept for glass panel conveyors
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
D. Prust and H. Murrenhoff,
2007,
pp. 231-244,
September 2007
view abstract
In the production of flat screens, semi conducting material is deposited onto large glass panels. This requires a considerable number of different processes similar to those used in the fabrication of computer chips. As the production cannot be carried out on a single device, the panels have to be transported between different working stations, avoiding contamination or damage. For this purpose, conveyors comprising of a number of wheels, part of which are electrically driven, are state of the art. However, these wheel conveyors are prone to impair the glass substrates due to skid marks on the glass surface. The general workaround for this problem is the use of wheels whose skid marks can be easily removed. Yet, in order to reduce the production cost of the displays, cleaning processes should be kept to a minimum, as they do not contribute to the desired function of the display, but only cover up for imperfect manufacture.
A significant amelioration could be achieved by replacing the wheel conveyor with a pneumatic pace drive comprising of an array of suction pads mounted to rodless cylinders. Their suction pads are capable of establishing a reliable connection with the glass surface, reducing the risk of slipping, and thus the extent and the amount of marks. In order to achieve a steady movement, the panel is passed on from one suction pad to the next. The combination of an optimised control strategy with an integrated design provides better functionality as well as low running costs.
This paper presents methods to optimise the design of pneumatic pace drives concerning running costs as well as accuracy.
Optimized Piston Guidance Design for Swash Plate Pumps
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-92-1,
U. Bräckelmann and D. Breuer and S. Stoll and U. Piepenstock,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 3,
pp. 249-259,
März 2010
view abstract
This paper describes the correlation between the piston guidance design and the efficiency characteristics of swash plate axial piston machines. It shows the approach on the basis of experimental investigations and, using examples, brings into focus the contact between pistons and cylinders, as this contact is highly stressed and characterized by a special complexity of tribological conditions. A well-tailored combination of guidance length and guidance clearance makes it possible to find the efficiency optimum for practical use.
Optimizing the PPV Setting in a Pneumatic System
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Hualan and X. Xinyu and Z. Hong,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 373-376,
April 2005
view abstract
Adjustable end position cushioning (PPV) at both ends of a cylinder can assist in achieving higher speeds and reducing cycle times by absorbing the impact energy during high-speed operation and also increase operating efficiency. However, until recently very little help and few tools were available to designers as to how to set PPV to keep the kinetic energy of a cylinder to a minimum. This document explains a method by which an optimized PPV setting can be achieved automatically.
Overcoming of self-excited oscillations and noise in hydraulic jet pipe servo-valve using magnetic fluid
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
S. Li and S. Jia and S. Wang,
2006,
pp. 121-130,
September 2006
view abstract
In order to overcome self-excited high frequency oscillations and noise appearing sometimes during the working of hydraulic jet-pipe servo-valve, application of magnetic fluid (MF) in hydraulic jet-pipe servo-valve is developed in this paper. Large damping can be introduced into the servo-valve if magnetic fluid is filled into the working gaps of hydraulic servo-valve torque motor. Construction of hydraulic jet-pipe servo-valve with magnetic fluid is introduced. The noise signals are tested and recorded when magnetic fluid is applied or not in the servo-valve. Experimental results are compared and analyzed using FFT and wavelet analysis. It is shown that noise of servo-valve is depressed when magnetic fluid is applied. Finally the damping force exerted on the torque motor armature by magnetic fluid is studied.
Parameter Identification as a Tool for Fluid Power System Development
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
A. Plöckinger and B. Manhartsgruber and R. Scheidl,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 387-399,
November 2003
view abstract
The dynamic behaviour of fluid power systems depends on a large number of parameters such as the mass of a moving part, the chamber volume, spring stiffness, orifice geometry, leakage, and friction. Some of these quantities are exactly known from the system design or can easily be measured in experiments. Other characteristics are difficult to predict. For instance, the relationship between pressure and flow-rate at orifices with complicated geometry or flowinduced forces on moving valve spools cannot be predicted without extensive CFD simulations. During the design of a fluid power component or system, such uncertainties are often bridged with simple models like the well known equation for flow through sharp-edged orifices. However, the discrepancy between such simple models and the real system behaviour may result in prototype malfunction. Parameter identification can be used to find the differences between the desired system dynamics and the prototype behaviour. This paper shows the use of a state-space system identification approach for the measurement of unknown parameters in a switching-type hydraulic drive.
Parameter Identification for a High-Performance Hydrostatic Actuation System Using the Variable Structure Filter Concept
S. R. Habibi and R. Burton,
In Journal of Dynamic Systems, Measurement, and Control,
2007,
volume 129,
pp. 229-235,
März 2007
view abstract
Parameter estimation is an important concept that can be used for health and condition monitoring. Estimation or measurement of physically meaningful parameters and their evaluation against predetermined thresholds allows detection of gradual or abrupt deteriorations in the plant. This early detection of faults enables preventative unscheduled maintenance that is of benefit to industries concerned with reliability and safety. In this paper, a recently proposed state estimation strategy referred to as the smooth variable structure filter (SVSF) is reviewed and extended to parameter estimation. The SVSF is applied to a novel hydrostatic actuation system referred to as the electrohydraulic actuator (EHA). Condition monitoring of the EHA for preventative unscheduled maintenance would increase its safety in applications pertaining to aerospace and would reduce its operational and maintenance costs.
Parameter Sensitivity Analysis for Force Control in Gold Wire Bonding Process
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
F. Li and Y. Yuehong and C. Zhaoneng and D. Han and L. Zhongqin,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 748-753,
April 2005
view abstract
In microelectronic packaging, wire bonding is an important technology that provides electrical interconnections between the bond pads on integrated circuit (IC) chips and leads on chip carrier using fine metal wires. During the interconnection, a key process is to minimize impact force and subsequently keep stable precise contact force in the transition of the capillary tip of bonding machine from non-contact to contact at the high-speed/high-accelerator. In the paper, the contact model is presented firstly. On the based of the model, the sensitivity analysis is adopted to optimize the dynamics performance of wire bonding. Finally, the switch fuzzy force control is described.
PARAMETRISED DYNAMIC MODEL OF A 4-WAY SPOOL VALVE - AN EXPERIMENTAL STUDY
Proceedings of the 2nd International Conference on Computational Methods in Fluid Power, FPNI'06, Aalborg, Denmark
ISBN: 87-89206-99-1 (CD),
B.K. Nielsen and R.T. Entwistle and T.O. Andersen and L.B. Tandrup,
2006, August 2006
view abstract
This paper addresses the problem of obtaining a dynamical simulation model of a spool valve, which is
parametrised by model parameters relating directly to measurable design parapmeters, or at least have a meaningfull
physical interpretation. By a model with these properties, the influence from different design trade-offs
may be evaluated by simulation without building several prototypes. The studied spool valve is intended for
use in a pilot valve, why for example modelling of leakage across the spool lands is important. The presented
model includes leakage, stiction, Coulomb friction, spool overlap and viscous damping associated with an actuator
device moving the spool. The electrical properties of the actuator device are not modelled since they are
neglegible compared to the remaining system. A thorough experimental verification is emphasised in the paper.
Parker’s new line of pilot operated servo proportional valves reduces cycle times and improves product quality
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
M. Gundlach,
2008,
pp. 168-175,
September 2008
view abstract
Parker Hannifin’s patented Voice Coil Drive (VCD®) technology has already improved the performance of many machines around the globe with the direct operated DFplus® valves. With the VCD technology Parker has achieved a successful breakthrough in the drive technology.
Robustness and dynamics of the VCD® drive is particularly suitable for pilot valves. Two new valve series benefit now from the outstanding performance of these VCD driven pilot valves.
The new pilot operated series D*1FP transfers the advantages of the Voice Coil Drive (VCD®) to larger frame sizes and thus high flow rates. With their high-resolution main stage feedback system and high-response voice coil drive, all DFplus valves achieve the highest possible performance linked to outstanding positioning. They are the best match for demanding open- and closed-loop applications.
The new series comes in the sizes NG10 (CETOP05), NG16 (CETOP07), NG25 (CETOP08) and NG32 (CETOP10). With flow rates up to 3000 l/min the advantages of the Voice Coil technology can now be used in almost any size of hydraulic circuits. The new safety concept allows to save additional shut-off valves in many cases. It works with a safe 4th position of the D1FP pilot valve, keeping the main stage hydraulically balanced at power down and the spool in a safe position.
The 2/2 way proportional throttle valves series TDP are available in sizes 32 to 100 and are used in applications where high flow has to be controlled with high precision and high dynamics. Typical applications are die casting, injection moulding and hydraulic presses. The TDP valve has a 2-stage design consisting of the DFplus pilot valve and the main stage with poppet and LVDT. With the DFplus pilot valve the TDP achieves extremely fast response times: from 14ms (NG32) up to 30ms (NG100) with an adjustment precision of 0.5% of the nominal flow. The active closed loop control enables the poppet to be positioned independent of the differential pressure, which can become as high as the maximum working pressure. The TDP has integrated electronics controlling both the position of the main poppet and the spool position of the DFplus pilot valve.
Robust design and long life time are benefits of the VCD for both direct and pilot operated valves. In addition to the dynamics, the control behaviour of the valves ensures high stability and easy, time saving installation and set-up.
The Customer can expect more efficiency by enhanced process and product accuracy through high-precision manufacture. These are the essentials to create hydraulic systems that drive machines to new technology levels - with reduced cycle times, improved product quality and minimum scrap rates.
Partially Continuously Variable Power-Split Transmission for Wheel Loaders
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
T. Fleczoreck and S. Kemper and H.-H. Harms,
2010,
volume 2,
pp. 621-632,
Juni 2010
view abstract
This contribution describes a partially continuously variable hydraulic-mechanical power-split transmission principle
for wheel loaders, in which the advantages of the common transmission technologies of wheel loaders are combined.
This concept offers a continuously variable transmission during the loading process, which is characterized by lower
frequently changing driving speeds and in particular by reversing and strong tractive forces while infeeding the pile.
Due to the abandonment of the torque converter, it has the advantage of high transmission efficiency especially during
reversing and infeeding the pile, which is similar to the common stepless hydrostatic drivelines with additional power
shift transmission. During the longer transports between the pure loading processes with higher driving speeds, the
demand for high transmission efficiency can be fulfilled better by manual transmissions. This is featured by the
presented concept and according to the commonly used power shift transmissions with torque converter.
PASSIVE BILATERAL TELEOPERATION OF A HYDRAULIC ACTUATOR USING AN ELECTROHYDRAULIC PASSIVE VALVE
P. Y. Li and K. Krishnaswamy,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 43-56,
August 2004
view abstract
A passive control scheme for the bilateral teleoperation of a electrohydraulic actuator and a motorized joystick is
proposed. The overall system enables a human operating a motorized joystick to feel as if he is manipulating a rigid
mechanical tool with which the work environment is also in contact. By ensuring that the closed loop system behaves
like a passive two port device, safety and stability when coupled to other systems are improved. The control scheme is
developed by first using previously developed active feedback to passify a four way proportional directional control
valve, and then by the design of an intrinsically passive teleoperation controller. The coordination error between the
joystick and the hydraulic actuator converges to zero for sufficiently low manipulation bandwidth. Experimental results
verify the characteristics of the control scheme.
Passive Tele-operation of Pneumatic Powered Robotic Rescue Crawler
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
V. Durbha and P. Li,
2010,
volume 2,
pp. 451-466,
Juni 2010
view abstract
In this paper, a passive bilateral tele-operation of a pneumatic powered robotic crawler is presented. The crawler is
designed to be four legged with three degrees of freedom along each leg. The front two legs of the crawler are remotely
maneuvered by means of a Phantom haptic interface, with hind legs tracing the path generated by the front legs. The
crawler dynamics are obtained in the joint space of the crawler. A simplified model of Phantom dynamics is used in the
controller design for achieving the required tele-operation. A passive controller is designed in the crawler joint space
to achieve bilateral tele-operation. In this paper, simulation results of tele-operation of only a single leg of the crawler
are provided. Results show good tracking performance of the controller. Preliminary implementation results along a
single actuator have been encouraging.
Passivity-Based Impact and Force Control of a Pneumatic Actuator
Yong Zhu and Eric J. Barth,
In Journal of Dynamic Systems, Measurement, and Control,
2008,
volume 130,
März 2008
view abstract
To carry out stable and dissipative contact tasks with an arbitrary environment, it is critical for a pneumatic actuator to be passive with respect to a supply rate consisting of the spool valve position input and the actuation force output. A pseudo-bond graph model with the inner product between spool valve position input and actuation force output as a pseudo-supply rate is developed. Using this pseudo-bond graph model, an open-loop pneumatic actuator controlled by a four-way proportional valve can be proven to not be passive with respect to the pseudo-supply rate. Conversely, it can also be proven to be passive with respect to the pseudo-supply rate under a closed-loop feedback control law. The passivity of the closed-loop pneumatic actuator is verified in impact and force control experiments. The experimental results also validate the pseudo-bond graph model. The pseudo-bond graph model is intended for passivity analysis and controller design for pneumatic actuation applications where contact stability (such as robotic assembly) and/or stable interaction with a passive environment (such as human-robot interaction) is required.
Passivity of Fluid Transmission Line Models
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2004
B. Manhartsgruber,
Professional Engineering Publishing,
ed. Burrows, C.R. and Edge, K.A. and Johnston D.N.,
2004,
pp. 99-108,
Payload Estimation In Four Wheel Drive Loaders
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
J. Hindman and R. Burton and G. Schoenau,
2007,
volume 3,
pp. 177-185,
Mai 2007
view abstract
Dynamic payload estimation in hydraulically actuated linkages is a diffucult task compounded by friction, compressibility, manufacturing variation, and linkage nonlinearity among other things. This problem is made even more difficult when the
linkage is mobile as is often the case with off-highway equipment such as four-wheeldrive loaders, cranes, and excavators. The rigid body motion of this type of equipment
affects the gravitational loads seen in the linkage and impact the payload estimate. The commercially available state-of-the-art load estimation solutions rely on the mobile
machine becoming pseudo-static in order to maintain accuracy. This requirement increases the time required to move the material and decreases the productivity of the machine. A novel solution to this problem that enables the machine to remain dynamic and still accurately estimate the payload is discussed in this paper. Development and implementation on an actual four-wheel-drive loader is shown.
PCCI Control Authority of a Modern Diesel Engine Outfitted With Flexible Intake Valve Actuation
Anup M. Kulkarni and Karla C. Stricker and Angeline Blum and and Gregory M. Shaver,
In Journal of Dynamic Systems, Measurement, and Control,
2010,
volume 132,
September 2010
view abstract
Premixed charge compression ignition (PCCI), an advanced mode combustion strategy, promises to simultaneously deliver the fuel efficiency of diesel combustion and the ultralow NOx emissions that usually require advanced exhaust aftertreatment. A flexible, computationally efficient, and whole engine simulation model for a 2007 6.7 l diesel engine with exhaust gas recirculation (EGR), variable geometry turbocharging (VGT), and common rail fuel injection was validated after extensive experimentation. This model was used to develop strategies for highly fuel-efficient and ultralow NOx emission PCCI. The primary aim of this modeling investigation is to determine the PCCI control authority present on a modern diesel engine outfitted with both conventional actuators (multipulse fuel injectors, EGR valve, and VGT) and flexible intake valve closure modulation, which dictates the effective compression ratio. The results indicate that early fuel injection coupled with ECR reduction and modest amounts of EGR yield a well-timed PCCI exhibiting 70%+ reductions in NOx with no fuel consumption penalty over a significant portion of the engine operating range.
PCM Control in Mobile Hydraulics
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Laamanen and M. Linjama and M. Vilenius,
2004,
pp. 311-320,
Juni 2004
view abstract
The basic idea of digital hydraulics based on the PCM (Pulse Code Modulation) control is that several
on/off valves with different flow capacities are connected in parallel and then by switching valves on and
off it is possible to implement stepwise adjustable flow control. This kind of control system can be used
instead of existing proportional or even servo valves. Most of the earlier PCM studies have concentrated
on pneumatic and hydraulic systems with relative light loads and thus, higher pressure levels and flow
demands have got less attention. In this study, possibilities and challenges of a mobile hydraulic PCM
control system are discussed and it is compared to existing control systems. In addition, experimental
tests are made in a boom mock-up.
Performance Characteristics of Magneto-Rheological Dampers for Semi-Active Structural Control
Proceedings of the Third World Conference on Structural Control
B. Manhartsgruber and R. Scheidl,
2003,
pp. 555-560,
PERFORMANCE LIMITATIONS OF A CLASS OF TWO-STAGE ELECTRO-HYDRAULIC FLOW VALVES
R. Zhang and A. G. Alleyne and E. A. Prasetiawan,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 47-53,
April 2002
view abstract
By examining the dynamics of a popular type of two-stage electronic proportional valve, this paper addresses its
performance limitations, with both cautions in control implementation and suggestions in valve design. While several
benefits do exist, there are limitations to the closed loop performance of the valve when it is included in a valvecontrolled electro-hydraulic system. These limitations come from the structural feature that the pilot flow not only controls but also contributes to the total flow. Although for steady state performance this design gives a higher flow efficiency, for dynamic performance it results in zeros in the open loop transfer function, which will limit the closed loop
bandwidth of a flow control system. A non-linear analytical model of this particular type of valve is derived first. It is
then simplified as a reduced order linear model with the inherit system zeros illustrated. Validation of the analysis is
obtained by experimental results on a testbed.
Phase-Shift High-Speed Valve for Switch-Mode Control
James D. Van de Ven and Allan Katz,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Januar 2011
view abstract
Hydraulic applications requiring a variation in the speed or torque of actuators have historically used throttling valve control or a variable displacement pump or motor. An alternative method is switch-mode control that uses a high-speed valve to rapidly switch between efficient on and off states, allowing any hydraulic actuator to have virtually variable displacement. An existing barrier to switch-mode control is a fast and efficient high-speed valve. A novel high-speed valve concept is proposed that uses a phase shift between two tiers of continuously rotating valve spools to achieve a pulse-width modulated flow with any desired duty ratio. An analysis of the major forms of energy loss, including throttling, compressibility, viscous friction, and internal leakage, is performed on a disk spool architecture. This analysis also explores the use of a hydrodynamic thrust bearing to maintain valve clearance. A nonoptimized design example of a phase-shift valve operating at 100 Hz switching frequency at 10 l/min demonstrates an efficiency of 73% at a duty ratio of 1 and 64% at 0.75 duty ratio. Numerous opportunities exist for improving this efficiency including design changes and formal optimization. The phase-shift valve has the potential to enable switch-mode hydraulic circuits. The valve has numerous benefits over existing technology yet requires further refinement to realize its full potential.
Physically Correct Hydraulic System Simulation with Mass Conservative Approach
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
C. Riedel and H. Murrenhoff and C. Stammen,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 523-534,
März 2010
view abstract
This article illustrates the benefits of a mass conservative one-dimensional system simulation.
A calculation with mass flow instead of volume flow increases the predictability and efficiency of system simulation tools in fluid power. State of the art simulation tools make use of simplified differential equations. Especially in closed systems or long-term simulations, the volume flow based approach leads to significant variations of simulation results as balancing of flow parameters and their integration to potentials lead to a violation of the equation of continuity. However, with a mass flow and energy conservative approach one obtains a physically correct model implemented in the simulation tool DSHplus. This paper shows how the fundamental equations are implemented into the different component models. Furthermore, this article depicts under which circumstances and to what extent the new basis for calculation increases the accuracy of the simulation. The new basis of calculation enables further implementation of thermo-hydraulic and multi-phase flow models such as cavitation or particle transport into the concentrated parametric system simulation.
Physical Modelling of the Hydraulic Drive (in Czech)
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
P. Noskievič,
2008,
pp. 294-301,
September 2008
view abstract
The paper deals with the realization of the lumped parameters model of the
hydraulic circuit using the physical modelling. The comparison of the approaches for the
model realisation based on the block diagram and physical model is described. The block
oriented simulation programmes use the cybernetic approach and follow the signal flow,
physical modelling is based on the physical basis of the system and follows the energy flow.
The paper is focused on the simulation program LMS AMESim and his use for the modelling
of the systems with complex structure. The simulation program AMESim is equipped with the
different model libraries – like library for mechanic, hydraulic, pneumatic, electric, thermal
and control systems. The creation of the simulation model is based on the principle of the
physical modelling and using the connection of the icons of the basic main components is very
easy in the user friendly graphical environment. After the structure of the system is defined
the suitable mathematical model to each component must be chosen from the model libraries
and in the next step the model parameters are set up. The next step is the numerical
simulation. Finally it is possible to draw all state variables, to analyse the variables and
whole system. The environment supports also the analysis of the dynamic properties of the
system, calculation and drawing of the basic dynamic characteristics and design of the
control systems, closed loop control systems. The simulation of the planar mechanism with
the linear hydraulic servo drive with controlled hydraulic unit is shown in the paper.
Piezoelectrically actuated hydraulic valve design for high bandwidth and flow performance
D. T. Branson and F. C. Wang and D. N. Johnston et al.,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2011,
volume 225,
pp. 345-359,
Mai 2011
view abstract
The performance of hydraulically actuated machine systems could be improved with the use of valves that have high bandwidth and high flowrates under low pressure drops. Although high flowrates can be achieved using very large spool strokes and/or diameters, the overall bandwidth of the valve will be reduced. Research has therefore been undertaken on a prototype valve design incorporating the Hörbiger plate principle, which utilizes multiple metering edges to allow high flowrates to be obtained at low pressure drops and small poppet displacements. The valve is directly activated using a piezoelectric actuator to achieve a fast dynamic response. Valve performance is assessed using mathematical model that includes the piezoelectric actuator and power amplifier, the supply flow, fluid squeeze forces, end stop response, and valve mechanical components. The steady state relationship between valve flow, force and pressure drop, and the fluid inertance, were determined using computational fluid dynamics software. The simulation model has been validated using test data obtained from experimental tests undertaken on a prototype valve. Good agreement is obtained between the predicted and measured results and it is shown that the valve is capable of opening or closing fully in less than 1.5ms, and can pass a flow of 65l/min at a pressure drop of 20bar.
Piloting the valve spool by using a through axial shaft
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
M. A. Elgamil,
2006,
pp. 429-436,
September 2006
view abstract
In this paper, a method to use a through axial shaft passing through the spool in piloting its position is described. The shaft has helical like grooves, while the spool has through holes in front of these grooves. Turning the shaft about its axis establishes the variation in the control orifice areas between the holes and the grooves, and then connects the pilot pressures at the two spool ends with the supply pressure and/or the tank pressure. Due to the helical like groove shape, the spool movement results in regaining the original control orifice areas values. This response provides a feedback action that makes the spool position follows the shaft turning angle value.
PIPING ELEMENTS MODELLING OF CENTRAL GREASE LUBRICATION SYSTEM
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
J. Zapletal,
2000,
pp. 509-518,
September 2000
view abstract
This contribution deals with the piping elements modelling of central grease lubrication system. There was
developed a mathematical model of a central lubricating system and consecutively, its computer simulation by
the program DYNAST was realised. The obtained results of the simulation were compared with the results
obtained experimentally by the testing equipment subsequently, the mathematical model was defined more precisely.
Pneumatic Cabin Suspension for Mobile Agricultural Machines
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
K. Deprez and M. De Coninck,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 221-232,
März 2010
view abstract
This paper develops a pneumatic cab suspension system to improve the low-frequency vibrational comfort on mobile agricultural machines. Assessment of the comfort situation of the operator of a combine harvester shows that the European action and limit values for low-frequency vibrational comfort are violated for several working conditions of the machine. The frequently used rubber cabin mounts have a deteriorating effect on the comfort of the operator in the low-frequency region. An alternative cabin mount is designed consisting of pneumatic components. A non-linear parametric model based on first principles is derived and verified experimentally. A linearized model of the cab mount is incorporated in a six degree of freedom linear model of the cab suspension, making it possible to predict the comfort for different working conditions. The predictions are verified by evaluation of a physical cabin suspension system on a hydraulic test rig. In-situ measured vibration signals enable the evaluation of the suspension under controlled lab conditions.
Pneumatic Component Characterization: Use of Measured Stagnation Pressures
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
S. Sesmat and D. Hubert and D. Gautier and E. Bideaux,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 223-234,
März 2010
view abstract
This paper presents the advantages of using upstream and downstream stagnation pressures instead of static pressures to determine the flow characteristics of a pneumatic component. A proposal to measure directly stagnation pressures (sum of static and dynamic effects) is compared to the use of calculation to obtain the stagnation pressure from static pressure measurement. The use of an expanded section to measure directly the downstream stagnation pressure enables to obtain the whole conductance curve of the component, making easier the parameters determination.
PNEUMATIC LANDSLIDE GENERATOR
H. M. Fritz and P. Moser,
In International Journal of Fluid Power,
2003,
volume 4,
pp. 49-57,
April 2003
view abstract
A pneumatic landslide generator was developed specifically for the investigation of landslide generated impulse
waves in reservoirs, lakes, bays or oceans in a two-dimensional physical laboratory model. The landslides were successfully
modelled with an artificial granulate. The pneumatic landslide generator was designed to control the slide
impact characteristics and enable exact reproduction and independent variation of single dynamic slide parameters. The
two pneumatic linear drives catapulted the landslides to velocities up to 7.3 m/s on an acceleration distance of less than 0.9 m. The operation of linear drives 3.6 times beyond their certified velocity range is highlighted. Total masses of up to 174 kg were accelerated. The slotted cylinders enabled a compact mechanical design and a stroke length equal
to 70 % of the overall cylinder length. The pneumatic deceleration by temporary airflow and pressure gradient reversal is presented. Real time valve response problems in high-speed applications are discussed and solved with preset trigger signals programmed to the pneumatics control unit. The behaviour of the whole pneumatic system was successfully
simulated with the computer aided cylinder optimisation system software (CACOS). The measurements and numerical
simulations are compared.
Pneumatic Positioning System of Process Valves
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
E. Mäkinen and T. Virvalo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 315-319,
April 2005
view abstract
Pneumatic cylinders are most commonly used positioners of process valves. Another large application field of pneumatic cylinder drives is the material handling. Very demanding specifications are presented by EnTech for these devices in process industrial applications. There are large differences of basic characteristics of these two applications. The fiction forces are dominant in process valve application while inertia loads are dominant in material handling applications. Good performance specifications have been achieved with pneumatic cylinder drives in material handling applications using state controllers. Achieved performance is competitive with EnTech specifications. In this study it is found that these demanding performance specifications can be fulfilled with high quality commercial electro-pneumatic servo valve, reasonable good position sensor, and state controller. The tuned position loop gain of the state controller is almost ten times higher than can be used with the P-controller. The basic design of the state controller is presented. The final tuning is done with try-and-error method. Measured step responses as well as step ramp responses are presented. The limit of dynamics for servo valve is studied lowering the dynamics of the servo valve by filtering its control signal. According to this study the dynamics of servo valves is not very critical in this kind of position control applications. The main conclusion of this study is that presented specification can be fulfilled with a high quality electro-pneumatic servo valve and a linear state controller.
Pneumatic Positioning System of Process Valves
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
E. Mäkinen and T. Virvalo,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 315-319,
April 2005
view abstract
Pneumatic cylinders are most commonly used positioners of process valves. Another large application field of pneumatic cylinder drives is the material handling. Very demanding specifications are presented by EnTech for these devices in process industrial applications. There are large differences of basic characteristics of these two applications. The fiction forces are dominant in process valve application while inertia loads are dominant in material handling applications. Good performance specifications have been achieved with pneumatic cylinder drives in material handling applications using state controllers. Achieved performance is competitive with EnTech specifications. In this study it is found that these demanding performance specifications can be fulfilled with high quality commercial electro-pneumatic servo valve, reasonable good position sensor, and state controller. The tuned position loop gain of the state controller is almost ten times higher than can be used with the P-controller. The basic design of the state controller is presented. The final tuning is done with try-and-error method. Measured step responses as well as step ramp responses are presented. The limit of dynamics for servo valve is studied lowering the dynamics of the servo valve by filtering its control signal. According to this study the dynamics of servo valves is not very critical in this kind of position control applications. The main conclusion of this study is that presented specification can be fulfilled with a high quality electro-pneumatic servo valve and a linear state controller.
Pneumatic servo valve models based on artificial neural networks
J. Falcao Carneiro and F. Gomes de Almeida,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2011,
volume 225,
pp. 393-411,
Mai 2011
view abstract
This paper presents a study where static models for the flow stage of three-port pneumatic servo valves are obtained using artificial neural networks. A new approach to build the models is introduced in detail. This approach considers two distinct models: for simulation purposes, the air mass flow is determined for a given working pressure and command input; for control purposes, the command input is determined given the working pressure and the desired air mass flow. This approach enables the use of air mass flow as the synthesized control action, thus rendering the overall pneumatic system affine. Therefore, control techniques requiring this condition on the system model can be directly used. The use of this approach in two different industrial pneumatic servo valves is presented in detail. A comparison between the different characteristics of each servo valve is also provided.
Pneumatic servovalve models using artificial neural networks
Power Transmission and Motion Control 2006
ISBN: ISBN: 08-6197-135-3,
J. F. Carneiro and F. Gomes de Almeida,
2006,
pp. 195-208,
September 2006
view abstract
This paper presents a study where static models of the flow stage of a 3/2 pneumatic servovalve are obtained using artificial neural networks. For simulation purposes, a direct model is proposed in which the mass flow is determined for a given working pressure and control input. For control purposes, an inverse model is proposed in which the command
input is determined given the working pressure and the desired mass flow. This approach enables the use of mass flow as the synthesised control action, thus rendering the overall pneumatic system affine. Therefore, control techniques requiring this condition on the system model can be directly used.
Under normal working conditions, both servovalve models provide an excellent agreement with experimental results taken from an industrial pneumatic servovalve. The direct model has a maximum error of 1.25% of the nominal mass flow (NMF). When the output of the inverse model is applied to the servovalve to achieve a desired mass flow, the error obtained has a maximum value of 1.3% NMF. Furthermore, the pressure gain curves of the direct and inverse models have a maximum error of, respectively, 2.44% and 1.72% of the supply pressure.
Portable Remote Control for Teleoperated Hydraulic Mobile Machine
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
J. Uusisalo and J. Vilenius and A. Vuohijoki and S.−M. Hirvonen and O. Karhu and K. Huhtala,
2007,
volume 3,
pp. 35-45,
Mai 2007
view abstract
A portable remote control for short-range teleoperation is developed at the Institute of Hydraulics and Automation in the Tampere University of Technology. The remote control is based on a commercial game controller. Electronics of the game controller is redesigned and the wireless communication between the remote control and the machine is carried out with lightweight low-cost radio modems. Implementation of the portable remote control is introduced in this paper. Also, other alternative solutions to implement teleoperation of the machine are discussed.
Position Control of a Cylinder Using a Hydraulic Bridge Circuit With ER Valves
Seung-Bok Choi and Woo-Yeon Choi,
In Journal of Dynamic Systems, Measurement, and Control,
2000,
volume 122,
pp. 202-209,
März 2000
view abstract
This paper presents the position control of a double-rod cylinder system using a hydraulic bridge circuit with four electro-rheological (ER) valves. After synthesizing a silicone oil-based ER fluid, a Bingham property of the ER fluid is first tested as a function of electric field in order to determine operational parameters for the ER valves. On the basis of the level of the field-dependent yield stress of the composed ER fluid, four cylindrical ER valves are designed and manufactured. Subsequently, step responses for pressure drops of the ER valve are empirically analyzed with respect to the intensity of the electric field. A cylinder system with a cart is then constructed using a hydraulic bridge circuit with four ER valves, and its governing equation of motion is derived. A neural network control scheme incorporating the proportional-integral-derivative (PID) controller is formulated through the feedback error learning method, and experimentally implemented for the position control of the cylinder system. Both regulating and tracking position control responses for square and sinusoidal trajectories are presented in time domain. In addition, a tracking durability of the control system is provided to demonstrate the practical feasibility of the proposed methodology.
POSITION CONTROL OF A PNEUMATIC SERVO CYLINDER USING FUZZY-SLIDING SURFACE CONTROLLER
J.-C. Renn,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 19-25,
Dezember 2002
view abstract
In this paper, both the PID and fuzzy-sliding surface controller are applied to the position control of a proportional-valve-controlled pneumatic rodless cylinder. Because of the highly nonlinear basic equations of pneumatic systems, the modelling of such a pneumatic servo is excluded from this paper. Besides, it is usually quite difficult to obtain a satisfactory position control of a pneumatic rodless cylinder because an apparent dead-zone in the response curve during the starting phase always appears. The dead-zone signifies a serious response delay. One reason for such a response deadzone is the stick-slip friction and the nonlinear deadband of the proportional valve. In this paper, therefore, the chattering output of sliding mode control is introduced to reduce the effect of stick-slip and the nonlinear fuzzy-logiccontroller is employed to control this unmodelled and highly nonlinear system. Accordingly, the fuzzy-sliding surface controller is proposed, which is exactly the combination of the fuzzy-logic-controller with the sliding mode controller.
There are two key features of this control scheme. One is the easier implementation of the controller as compared with
that of the conventional fuzzy-logic-controller because the number of controller input is reduced by half. The other is
the ability to reduce the response dead-zone during the starting phase. Finally, a series of experiments are carried out and the experimental results prove that the fuzzy-sliding surface controller is superior to the conventional PID controller.
Position control of high performance hydrostatic actuation system using a simple adaptive control (SAC) method
S. H. Cho and R. Burton,
In Mechatronics,
2011,
volume 21,
pp. 109-115,
Februar 2011
view abstract
This paper deals with the issue of position tracking control of a high performance hydrostatic actuation
system using simple adaptive control. For energy-efficiency and savings, a speed-controlled fixed displacement
pump is utilized to drive a symmetrical linear actuator instead of a directional control servo
valve. The whole control system is composed of a pair of interconnected subsystems, that is, a feedback
control system and a feedforward control system to enhance the tracking performance. The experiment
using the proposed control scheme has been performed and a significant reduction in position tracking
error is achieved compared to a conventional PID control.
Positioning Control of a Hydraulic Press by a Variable Speed Motor
Proceedings of Bath Workshop on Power Transmission and Motion Control - PTMC 2002
ISBN: 1 86058 379 2,
R. Scheidl and G. Hametner,
Professional Engineering Publishing,
ed. C. R. Burrows and K. A. Edge,
2002,
pp. 203-214,
September 2002
view abstract
For a hydraulic press controlled by the rotational speed of the pump, a positioning controller is developed. The controller has to meet various requirements concerning accuracy, robustness, and rise time. This results in a state controller adapting to position in a pressure-dependent way. Controller performance is investigated by simulation and experiments. The influence of pump pulsations is shown to be very small, whereas the implementation of a motor speed feedback makes a big difference.
Position tracking control of a clamp-cylinder for energy-saving injection moulding machines with electric-hydrostatic drives
S. H. Cho and S. Räcklebe and S. Helduser,
In Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering,
2009,
volume 223,
pp. 479-491,
Juni 2009
view abstract
This paper deals with the issue of position tracking control of a clamp-cylinder for an injection moulding machine with electric-hydrostatic drives. In order to accommodate mismatches between the real plant and the model used for controller design, discrete-time sliding mode control is developed by combining a velocity feedforward loop. From tracking control experiments, it is shown that significant reduction in position tracking error is achieved through the use of a sliding model control scheme. The effect of dry-cycle time on position tracking error is examined for the possibility of attaining a high-speed injection moulding machine.
Position Tracking Control of a Miniature Water Hydraulic Rotary Actuator
Russell Sindrey and Gary M. Bone,
In Journal of Dynamic Systems, Measurement, and Control,
2009,
volume 131,
November 2009
view abstract
Over the past 20 years, research in the field of miniature actuators has increased substantially due to advances in smart material fabrication, semiconductor chip technology, and computer processing capability. Hydraulic cylinders offer many potential benefits as miniature actuators, including high power-to-weight ratio, mechanical stiffness, smooth motion, and the potential for high positional accuracy. Despite their benefits, the control of hydraulic cylinders with bore diameters under 10 mm has not been previously studied. The most significant obstacle to implementing the use of miniature cylinders is the unavailability of off-the-shelf proportional valves that are compatible with hydraulic fluid and precise enough for the position control task. In this paper, two novel model-based nonlinear control strategies are presented for the position control of a rotary actuator powered by two 4 mm bore diameter cylinders. Four off-the-shelf, low cost, 2/2 on/off miniature solenoid valves were used to control the flow of water to and from the cylinder chambers. A novel valve coordination scheme is also presented that allows the on/off valves to approximate the behavior of a proportional valve. The tracking performance of each controller was experimentally tested and both controllers were found to achieve steady-state positioning accuracies of the cylinders within ±0.07 mm. The robustness of the controllers to changes in payload mass and vertical orientation was also tested. Results from several experiments are presented and compared.
POSSIBILITIES OF MODERNIZATION OF A PNEUMATIC MANIPULATOR CONTROL CIRCUIT
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
A. Guzowski,
2004,
pp. 221-227,
Juni 2004
view abstract
The subject of this work was to modernize a control circuit of a pneumatic manipulator. To
achieve this, two independent pneumatic manipulators, controlled by older (type) generation
control circuits were tested. The first manipulator consisted of two modules: A linear motion
module and a grasper. The second manipulator consisted of a linear motion module, a swing
module and a grasper. The control of each element was done with a PLC controller. The first
step of this study was to describe the circuit and its control circuit before it was modernized,
describe the kinematic diagram (schematic) and characteristics of its elements. The second
stage is a proposal of automation of the circuit, generation of input and output control signals,
creation of operation algorithms and electrical circuit schematic. The final stage was to create
a PLC control program. The main goal of this project was to create a system of cooperation
for two manipulators. This can be used for example to service a given technological process.
So far the first stage has been completed and the control signals were generated. Current work
is focused on algorithms and their description. First conclusions were related to the costs of
the modernization of the system. Manipulators that are produced today are too big of an
expense for many companies. A modernization project and especially an automated cycle lead
to decrease of those costs. An extra gain is a smaller space occupied by the control circuits.
Many tasks carried out by these circuits are taken over by PLC controllers. This allows to
decrease complexity of electrical circuits. Modernization also offers an increase in quality of
companies work what has a great impact on companies position on the market.
Possibilities of Numerical Modeling of Fluid Flow in the Hydrodynamic Coupling (in Czech)
The 19th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 80-02-01809-5,
M. Golka and M. Kozubková,
2006,
pp. 255-264,
Mai 2006
view abstract
This paper deals with modeling of the fluid flow in the hydrodynamic coupling.
Hydrodynamic coupling uses for transmit of the torque the hydrodynamic effect of the
rotating fluid. Transmission of energy is conditioned by a closed circuit of the working fluid
between the pump 1 and turbine wheel 2. These guide vanes are located inside a shell 3 (Fig.
1). For its simple construction, easy maintenance, fast and stepless start-up of the shaft load
is using in many machinery applications.
Although hydrodynamic coupling belongs to the simplest hydrodynamic machines, exact
solution of the flow fields for various operating regimes have not been found yet.
Hydrodynamic coupling parameters are determined from model theory of similarity and for
visualisation of the fluid flow inside a coupling it is possible to use only very technically and
financially demanding methods like LDA or Gamma Tomography.
This paper deals with different way of modeling of the fluid flow inside hydrodynamic
coupling that is utilization of finite volume method. Regime of fluid flow is in this solved case
partially laminar and partially turbulent, so for the computation turbulent statistic models
were used. Fluid flow is solved as two-phase (fluid + air) with free-surface flow and both of
the phases are defined as incompressible and independent of temperature. The case was
solved for two variations of the boundary conditions. In a first one rotational speed for both
pump and turbine wheel was set up and flow field was solved for two main regimes of
coupling run and for two various volumes of fluid in the coupling. Flow field is illustrated by
means of fluid volume fraction contours and contours of total pressure (Fig. 2). In the second
variation rotational speed for pump wheel only was set up and inactive turbine wheel was run
up by the hydrodynamic effect of the fluid. Main parameters of the coupling were determined
in accordance with literature. Nowadays computation on a model of real hydrodynamic
coupling, where it would be possible to compare obtained data from this model with data
obtained experimentally, is executing. Coupling test facility is described in the end of this
paper.
Possible Methods for Biodynamic Feedthrough Compensation in Backhoe Operation
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
H. C. Humphreys and W. J. Book,
2010,
volume 2,
pp. 489-498,
Juni 2010
view abstract
This research presents an investigation on the effects of biodynamic feedthrough on an advanced backhoe control
system. This previously developed backhoe user interface uses coordinated position control with haptic feedback and is
used as a testbed for this research. Results indicate that the coordinated control provides more intuitive operation that
is easy to learn, and the haptic feedback relays meaningful information back to the user in the form of force signals
from digging forces and system limitations. However, they also show that the current system has significant problems
with biodynamic feedthrough. Biodynamic feedthrough refers to the phenomenon where the motion of the controlled
device excites motion of the operator, resulting in undesirable forces applied to the input device and control
performance degradation. According to the literature, and to industry backhoe and excavator interface designers, this
is also a significant problem in state-of-the-art user interfaces. This work presents simulation studies on several
possible methods for biodynamic feedthrough compensation.
Potential of Cyberspace with Virtual Reality and Soft Computing for Advancing Fluid Power Development
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
S. C. Fok and S. B. Tor and L. P. Khoo,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 81-100,
view abstract
No abstract available
Potentials of a Numerical Tool for the Simulation of Flow in External Gear Machines
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1758-7,
P. Casoli and A. Vacca and G. L. Berta,
2007,
volume 1,
pp. 251-267,
Mai 2007
view abstract
This paper deals with the numerical prediction of the flow in external gear machine. As well known, a crucial aspect of gear machines is the variable offset of the axes of rotation of both gears in operation, as produced by pressure distribution in the chamber: which means that gears work in different positions from the nominal ones, i.e. those deduced from the machine drawings. In this work, on the basis of simulated results,
several considerations about the effects of the actual position of gears centres on the main characteristics of the flow in external gear machine are developed.
The model used for the calculations has been developed by the authors and is named HYGESim (HYdraulic Gear machines Simulator). HYGESim permits a detailed evaluation of the flow inside gear pumps and motors, accounting for the main
geometrical design parameters (e.g. shape and dimensions of the grooves on the bearing blocks, tooth profile, etc.). HYGESim consists of three different models strictly connected: a geometrical model (developed in the Pro/Engineer® environment), a fluid dynamic model and a module for the evaluation of forces and toques acting on the gears. These two latter are lumped parameters models (implemented in the AMESim® environment), utilizing a high number of parametric sub-models, written directly in C++ language.
Through the latest improvements implemented in HYGESim, the results discussed in the paper – referring to comparisons with data coming from experiments carried out on a stock pump – highlight how this simulation tool can be useful for an estimation of the actual position of both gears as a function of load pressure and shaft speed.
POWER BALANCE IN HYDRAULIC SATELLITE MOTORS SUPPLIED WITH OIL AND HFA - E EMULSION
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Śliwiński,
2008,
pp. 245-253,
Juli 2008
view abstract
Mineral oil and HFA-E emulsion are liquids which differ in viscosity, density and lubricant properties. Therefore,
supplying hydraulic satellite motors with these liquids, differences between quantity of hydraulic, volumetric and
mechanical losses are observed. These losses influence efficiency of conversion of hydraulic energy into mechanical
energy and thereby power balance of motors.
Power Control for Hydrostatic Transmission System with Energy Recuperation
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
P. Kucybala and S. Michalowski,
2010,
volume 2,
pp. 757-764,
Juni 2010
view abstract
This paper summarises the results of analysis and investigation of power control for a selected hydrostatic transmission
system with energy recuperation. The energy recovery system was developed for the fork lift drive. Braking energy is
stored in the hydro-pneumatic accumulator through the control of the hydraulic motor. The mathematical model of
hydrostatic transmission system with energy recuperation involves a pump, motor, hydro-pneumatic piston type
accumulator and necessary hydraulic control valves. Modeling and simulation tests were performed for different work
cycles to determine the key parameters of hydrostatic transmission associated with energy saving, such as: vehicle
velocity, working pressure of pump, motor and accumulator, etc. The aim of the research program was to determine the
efficiency of energy accumulation in the assumed work cycles and to find the optimal power control.
Power Management in Mobile Hydraulic Applications - An Approach for Designing Hydraulic Power Supply Systems
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
H. C. Pedersen,
2004,
pp. 441-451,
Juni 2004
view abstract
Throughout the last three decades energy consumption has become one of the primary design aspects
in hydraulic systems, especially for mobile hydraulic systems, as power and cooling capacity here is
at limited disposal. Considering the energy usage, this is dependent on component efficiency, but even
more important is the system topology. However, there are no rules or guidelines for what system topology
to choose for a given application, in order to obtain the most energy efficient system, nor for how
the energy should be distributed in the system.
This paper describes the approach taken in a project to develop rules and methods for designing and
controlling mobile hydraulic systems in the most energy efficient way, when also considering the operational
aspects of the system. The paper first describes the thoughts and ideas behind the project and then
focus on an automated approach to design the hydraulic power supply in the most energy efficient way,
when considering a number of load situations. Finally an example of the approach is shown to prove its
validity.
POWER MANAGEMENT IN OPEN CIRCUIT HYDRAULIC SYSTEMS
Proceedings of the 4th FPNI - PhD Symposium, Sarasota, Florida, USA, June 13–17, 2006
ISBN: 1-4243-0499-7,
H. C. Pedersen and T. O. Andersen and M. R. Hansen,
2006,
volume 1,
pp. 65-76,
Juni 2006
view abstract
hydraulic systems, where tendency today is towards replacing traditionally hydro-mechanically actuated or controlled
components with components being electrically controllable. This has not only brought with it new features and
functionality, but also new possibilities with regard to system utilisation and efficiency.
The focus of the current paper is therefore on the control of and power management in an open circuit hydraulic
system, when utilising the possibilities arising from being able to control both pump, valves and engine electronically.
This is done when also taking into account functionality as prioritised flow sharing and anti-stall of the diesel engine.
The paper first presents a model of a simple hydraulic system being driven by a diesel engine. Based on the model an
algorithm is presented for controlling the system in the most energy efficient way, when also considering the dynamics
of both the hydraulic system and the engine and also incorporating the prioritised flow sharing and anti-stall
functionality. Finally simulation results are presented showing the feasibility of the algorithm along with a discussion
of the algorithm.
Power Management Strategy for a Parallel Hydraulic Hybrid Passenger Vehicle Using Stochastic Dynamic Programming
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
J. J. Meyer and K. A. Stelson and A. G. Alleyne and T. O. Deppen,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 381-392,
März 2010
view abstract
Hydraulic hybrid vehicles can save fuel while maintaining performance due to the high power density of hydraulics. This paper investigates the best way to control a parallel hydraulic hybrid passenger vehicle to minimize fuel consumption while maintaining performance by using stochastic dynamic programming. A variety of drive cycles are used to form a Markov chain with velocity and acceleration as the states. A transition probability matrix is calculated to determine the probability of being in a future state given the current state. Using these statistics, stochastic dynamic programming develops a control law that can be implemented in real time without requiring exact knowledge of the drive cycle. The results show that stochastic dynamic programming increases fuel economy for two drive cycles.
Power Optimization for Multi-Actuator Pump-Controlled Systems
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
C. Williamson and M. Ivantysynova,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 91-102,
März 2010
view abstract
This paper presents a power optimization controller which minimizes fuel consumption for a multi-actuator system based on the efficiency characteristics of the engine and hydraulic pumps. Optimal steady-state operation is achieved while also satisfying the required transient performance of the machine. As an example, the power management method is applied to a 5-ton compact excavator with displacementcontrolled actuators. A detailed simulation model is used to evaluate the excavator for a typical digging cycle, resulting in a 17 % reduction in fuel consumption compared to the displacement-controlled system
without static power optimization.
Power Scaling Bond Graph Approach to the Passification of Mechatronic Systems—With Application to Electrohydraulic Valves
P. Y. Li and R. F. Ngwompo,
In Journal of Dynamic Systems, Measurement, and Control,
2005,
volume 127,
pp. 633-641 ,
Dezember 2005
view abstract
In many applications that require physical interaction with humans or other physical environments, passivity is a useful property to have in order to improve safety and ease of use. Many mechatronic applications (e.g., teleoperators, robots that interact with humans) fall into this category. In this paper, we develop an approach to design passifying control laws for mechatronic components from a bond graph perspective. Two new bond graph elements with power scaling properties are first introduced and the passivity properties of bond graphs containing these elements are investigated. These elements are used to better model mechatronic systems that have embedded energy sources. A procedure for passifying mechatronic systems is then developed using the four-way directional electrohydraulic flow control valve as an example. The passified valve is a two-port system that is passive with respect to the scaled power input at the command and hydraulic ports. This is achieved by representing the control valve in a suitable augmented bond graph, and then by replacing the signal bonds with power scaling elements. The procedure generalizes a previous passifying control law resulting in improved performance. Similar procedure can be applied to other mechatronic systems.
Power Transmission System Design - Modeling the Comparative Performance of Hydraulic and Electric Drives
Fluid Power Systems and Technology 1997 ASME International Mechanical Engineering Congress and Exposition
ISBN: 9780791818367,
A. M. Monaghan and D. G. Tilley and P. J. Chapple,
ASME,
ed. R. S. Chandran and S. S. Nair,
1997,
volume 4,
pp. 157-162,
November 1997
view abstract
Advancements in technology have resulted in an increasing range of power transmission drive options. Therefore it is becoming increasingly difficult to select the most appropriate drive for a particular application. This paper describes the initial findings of an investigation into the design and analysis of power transmission systems. A technique is presented, based on computer simulation,
which allows the comparative performance of alternative systems to be evaluated.
The simulation work required the development of computer models to represent the drive system components. The modeling algorithms adopted for the hydraulic and electric motors are described.
Results of a computer study investigating the relative efficiency of three alternative rotary drive systems are presented. The three systems considered were a basic valve controlled hydraulic circuit, a load sensing hydraulic circuit and an inverter fed induction motor drive system. The study demonstrates the ability of the computer simulation technique to predict and compare the performance of competing power transmission systems, thus providing a powerful analytical tool for the system designer.
Practical Method for Measuring Periodic Flow Rates and Impedances in Pulsating Oil Flows through a Pipe
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Chen and S. Washio,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 496-500,
April 2005
view abstract
The present paper provides an experimental method of finding simultaneously the pressure and the flow rate, and accordingly the hydraulic impedance, at any section of a pipe having a pulsating oil flow, from the pressure data detected at two fixed points separated by only a few hundred millimeters along the pipe, describing its theoretical basis, the experimental verifications and the procedure for practical use. The method is actually a modification of the kinetic differential pressure (KDP in acronym) method which one of the present authors developed to measure transient flow rates in oil hydraulic lines. Through measurements of impedances for a pipe with its end closed and also for a Helmholtz resonator usually used for pulsation reduction, the method has proved to be a reliable and convenient experimental tool.
Prediction and Improvement of Steady-State Performance of a Power Controlled Axial Piston Pump
Osama Gad and M. Galal Rabie and Refaat M. El-Taher,
In Journal of Dynamic Systems, Measurement, and Control,
2002,
volume 124,
pp. 443-451,
September 2002
view abstract
This paper deals with the static and dynamic behavior of a variable displacement bent axis axial piston pump with power control. A mathematical model is deduced to predict the performance of the pump and its controller. The pump static and dynamic characteristics are also evaluated experimentally. A good agreement between the experimental and theoretical results is obtained which validates the deduced pump model. A redesign of the original pump controller is carried out, in order to produce constant output power (hyperbolic P-Q relation). The proposed controller includes a hydraulic accumulator used as a gas spring. A mathematical model for the pump, equipped with the proposed controller, is developed and used for the computer simulation. The effect of the proposed controller parameters on the pump performance is studied. The proposed controller produced a P-Q relation too close to the required hyperbola. In the dynamic mode of operation, the transient pressure oscillations and settling time are considerably reduced, but the maximum over shoot is increased.
Prediction of Coiling Temperature of Hot Rolled Strip Based on Neural Network
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
H. Wang and Y. Wang and D. Zhu,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 731-735,
April 2005
view abstract
Hot scrip coiling temperature is one important parameter of performance index in hot rolled strip, and its control system is highly nonlinear. The coiling temperature of hot rolled strip is exactly predicted based on neural network (NN) by means of its approximation to any non-linear system and its ability of approximation to any nonlinear system and its ability of prediction. Additional momentum method, which is an improved BP algorithm, is used in the NN. A new coiling temperature control system based on NN combined with mathematical model is presented. Its feed-forward control is based on the NN, and its feed-backward control is based on mathematic model. Finally, the prediction by the NN shows that the control performance is satisfactory, and it can make mathematical model of coiling temperature identified.
Prediction of Failures in Hydraulic Pumps and Assesment of Failures Effects by FMEA Method
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
J. Fabis and E. Lisowski,
2010,
volume 2,
pp. 727-732,
Juni 2010
view abstract
Hydraulic pumps are basic components of hydraulic drive and control systems. They belong to devices where high
relative velocities occur. Combining with heavy dynamic loads that are caused by pressure changes makes hydraulic
pumps a component sensitive on failures and damages. Causes of that may depend on various factors such us: improper
pump installation, improper material used for pump components, bad quality of working liquid or finally inadequate
working conditions. The knowledge about possible failures is important for designers on the design stage or for
improving existing solutions because it gives possibility to react on identified risk and undertake preventive actions.
This papers presents analysis of failures and theirs effects in hydraulic pump, slide vane type by the use of FMEA
method (Failure Modes and Effects Analysis). For this purpose at the beginning the hydraulic pump was split into
components and subcomponents. The next step was selecting the most important component pairs and performing
specified task in the pump. For each component possible failures and its causes were defined. Next the failures were
grouped and classified by assessment its influence on pump operation. For FMEA analysis the own software was used
and results are shown in tables and graphs.
Prediction of Pump and Motor Performance by Computer Simulation
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
M. Ivantysynova,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 505-522,
November 2003
view abstract
The prediction of pump and motor performance for a given design of a displacement machine
requires a simulation model describing the flow of a compressible and viscous fluid from the
ports through the valve plate to the displacement chamber including the consideration of the
gap flow through the lubricating gaps sealing the displacement chamber. The change of pressure
in the displacement chamber resulting from the basic working process of the displacement
machine causes fluctuating forces and moments leading to oscillating micro motion of
moveable parts of the rotating group. The paper presents a modified version of the simulation
program CASPAR being developed at the Institute of Aircraft Systems Engineering. CASPAR
is based on a non-isothermal gap flow model considering the change of gap heights due
to micro motion of parts and due to surface deformations for all three connected gaps of a
swash plate axial piston machine. The program allows the calculation of real flow ripple at
both ports, further the calculation of the instantaneous cylinder pressure, the internal and external
volumetric losses, viscous friction forces, gap heights and oscillating forces and moments
exerted on the swash plate. The program represents a powerful design tool for this kind
of displacement machines.
Prediction of rotary hydrostatic drive’s volumetric losses
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
I. Pósa and J. Krchnár and K. Stračár,
2008,
pp. 315-322,
September 2008
view abstract
In this paper is presented diagnostic method of hydrostatic drive. The diagnostic
method is applied on the hydrostatic drive which includes 3-phased commutator elektromotor,
axial piston pump of swash plate design, axial piston motor of swash plate design,
dynamometer and plumbing.
The basic of the used method is design of the mathematical model of dynamic behaviour
of hydrostatic drive in C-code and adapted in MATLAB/Simulink® as S-functions. After
finishing the simulation model it can be simulated real states of the system. To have an
accurate and verified model, the torque and volumetric losses have been determined by
comparison of simulation model behaviour and real system output. This procedure is
repeated with real system outputs from the other measurements with different states of the
drive´s wear. There are differences between previous simulation outputs and real system
behaviour, in condition of same inputs. To reach the best accuracy of the model, torque and
volumetric losses have to be changed. These changes of losses refer to wear of component.
The values of volumetric losses at monitored time are inputs to training process of the
artificial neural network. These neural networks are able to make prognosis without defining
the mathematic function between input variables. The values of volumetric losses in time
periods, quantity of failures per year and operating life recommended by producer were used
to train the 2D neural networks. The outputs from the 2D neural networks were used as inputs
to the 3D neural network. The networks predict the trend of the volumetric losses.
Preliminary Approach to the Contact Stress in a Gerotor Pump
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
P.J. Gamez-Montero and E. Codina,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 303-314,
November 2003
view abstract
The aim of this first approach on this paper is to characterise contact stress of a gear set when
it works as part of an internal gear pump type gerotor. The performance of the gear set is
evaluated through analytical studies in order to obtain the maximum contact stress in the gear
teeth. Several cases have been considered, but two of them in particular will be presented in
this study. In order to compare and contrast the theoretical results, simulation and
experimentation have been carried out. A 2D simulation is been made by using the Finite
Element Method (FEM) for a particular case. An experimental approach using a prototype
model of the gear set provides the maximum contact stress on a pair of teeth through
photoelasticity measurement techniques for a particular case. Finally, the results are presented
and conclusions are exposed and discussed.
Preliminary Design Approach of Hydrostatic Piston Motor for Achieving a User-Defined Optimal Efficiency Point
Proceedings of the 1st International Conference on Computational Method in Fluid Power Technology, Melbourne, Australia
ISBN: 0-9578574-1-1,
H.-E. Kim and H.-S. Jeong and B.-S. Kang and D.-S. Jeong and Y.-B. Lee,
Fluid Power Net Pty Ltd,
ed. J. S. Stecki,
2003,
pp. 613-624,
November 2003
view abstract
Development of hydrostatic motor needs several aspects of considerations and many steps of
design processes. One of the most important viewpoints is the efficiency of the motor,
especially at a user-defined operating condition. Design of motor with good overall efficiency
is not an easy work and achieving an optimal efficiency at an user-defined operating point is
much more difficult work. In this paper, what to be considered and how to design in the
preliminary design stage to achieve this goal are considered. With the motor thus designed,
what is necessary to estimate the performance in advance of real experimental test is
discussed. Finally, how to adjust performance sensitive parameters of the designed motor is
discussed. As a result, automatic design of motor only from the given functional requirements,
estimation of the motor performance in advance of real experimental test and adjustment of
performance sensitive parameters can improve the overall performance of the motor in some
range at the operating condition in mind as shown.
PRELIMINARY DESIGN RULES FOR ELECTROHYDRAULIC POSITION CONTROL ACTUATION SYSTEM WITH STRUCTURE COMPLIANCE
Proceedings of the 2nd International FPNI PhD Symposium on FLUID POWER, July 3-5 2002, Modena, Italy
ISBN: 88-88679-00-6 (CD-ROM),
L. Yu and J.-C. Maré and Z. Wang,
2002, Juli 2002
view abstract
This communication deals with the design of electro-hydraulic position actuators in the presence of
structural anchorage or transmission compliance. Attention is focused on the definition of design rules to
be used by the designer during the first stage of actuation design of integrated actuation package (IAP).
The whole results are got from linear analysis of the actuator model, minimizing a modified integral of
time absolute error criteria (MITAE). Once introduced the employed methodology, the MITAE criteria is
compared to usual design criteria in absence of structural compliance for proportional control. Then, the
influence of structure compliance on performance is pointed up. Beginning with proportional control, the
study goes on partial state feedback using the actuator position / velocity / acceleration. It is assumed that
the natural damping of the electrohydraulic mode is 5% and that the structural damping is negligible.
Finally, the influence of servovalve and structure dynamics are discussed and compared with reference
values using the tracking error and response time. This leads to define generic design rules.
Present State and Future Development in Mechatronics and its Effect on Fluid Power Systems
Developments in Fluid Power Control of Machinery and Manipulators, Cracow 2000
ISBN: 83-86219-71-8,
G. K. Christensen and J. Zhou and F. Conrad and T. Sorensen,
Fluid Power Net Publication,
ed. A. Garbacik and J. Stecki,
2000,
pp. 155-180,
view abstract
No abstract available
Pressure and Vacuum Servo Control System Based on Vacuum Pump and Study of the System Control
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
L. Jinyun and D. Jingmin and F. Xiaoyun and L. Baoren,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 368-372,
April 2005
view abstract
A novel pressure and vacuum servo control system using a vacuum pump is presented in the Paper. The system combines vacuum technology and pneumatics servo control technology.
By applying different controllers (PD controller, intelligent gene fuzzy controller and Fuzzy-PID controller) to the system, the simulation and experimental results show that it is practicable and reasonable to adopt the fuzzy-PID control strategy in the pressure and vacuum servo control system based on vacuum pump. The servo control system behaves stronger robustness, better adaptive ability, higher steady control accuracy and faster response.
The study also show that the pressure and vacuum servo control system based on vacuum pump is feasible and can greatly realize the servo control of the vacuum signal with high accuracy and fast response.
Pressure based fault detection and diagnosis of a digital valve system
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
L. Siivonen and M. Linjama and M. Huova,
2007,
pp. 67-79,
September 2007
view abstract
Digital valve systems have some unique features concerning fault tolerance. The effect of valve faults can be compensated for if the fault is detected and the controller re-configured accordingly. Fault detection and diagnosis is the key to fault tolerance. If the type, location and magnitude of the fault are known, the system can adapt to it. This paper presents a way to detect faults from the system by using measured pressure signals. A test cycle is developed and tested with certain valve and sensor faults. The results show that it is possible to detect faults from the system using the presented method. Analysis also shows a way to calculate more detailed information of certain valve faults.
PRESSURE COMPONENTS STABILITY ANALYSIS: A REVISITED APPROACH
M. Alirand and G. Favennec and M. Lebrun,
In International Journal of Fluid Power,
2002,
volume 3,
pp. 33-46,
April 2002
view abstract
In this paper the stability of pressure relief valves and pressure reducers is analysed. MacCloy and Merritt have previously proven that the stability analysis of these two components can be viewed with the same calculation. The purpose
of this paper is to extend their results to other pressure control components and to add some other views of stability
analysis using a simplification of the dynamics linked to the generally small volume of the counter reaction chamber.
This simplification leads to a third order transfer function, which is easier to analyse. The static behaviour of both
the pressure relief valve and the pressure-reducing valve is explained using this transfer function. A proof is given that
the eigenvalues are heavily coupled using the roots calculation of a third order polynomial function. The analysis shows
that the inner mechanical control loop of these two components can be viewed as a PD force controller. Root loci are
used to understand the stability influences of certain design parameters. Other basic rules are also established.
Pressure Control in a Low-pressure Casting Furnace
Proceedings of the Sixth International Conference on Fluid Power Transmission and Control, ICFP'2005, Zhejiang, China, 5-8 April 2005
ISBN: ISBN: 7-5062-7402-7,
G. Belforte and M. Carello and A. Ivanov,
International Academic Publishers / Beijing World Publishing Corporation,
ed. L. Yongxiang and W. Qingfeng and L.Wei,
2005,
pp. 345-348,
April 2005
view abstract
The casting of light alloy components is a technology commonly used in aeronautic industry. This operation is possible, for example, using a low-pressure casting system, where it is important to control the temperature but also the maximum value and the time history of the pressure inside the furnace. For this reason it becomes important to study the pressurization circuit.
In this paper a theoretical and experimental study of the pressurization circuit of a low-pressure casting furnace is presented, to individuate the temporal behaviour of the pressure inside the furnace.
The main components of the system are: the flow regulation valves, the furnace, the connecting pipes among different parts of the system, the control unit and the related Sensors.
Particular attention has been paid to the experimental characterisation of the proportional valve with current-driven electro-pneumatic pilot. The opening of the principal valve is a function of the current of the pilot-valve. The characteristics, in terms of flow coefficients and response time, have been evaluated as a function of the upstream pressure and of the pilot current.
A lumped parameters model has been developed, in which it is possible to vary the following parameters: type of valve and its coefficients, volume and temperature of the furnace, size of connecting pipes and supply pressure.
The resistive and capacitive effects have been considered for the tube model but the inductive effect has been neglected. For the furnace only the capacitive effect has been take into account.
The influence of the different parameters on the furnace pressure has been evaluated; experimental results obtained from tests on single components have used to find the parameters of the numerical model.
The validation of the whole pressurizing furnace circuit model has been made with an experimental setup properly realised. For every working condition, a good agreement between numerical and experimental time history of the pressure inside the furnace has been obtained.
A further model validation has been made by using experimental results obtained by an existing foundry circuit. Also in this case good agreement has been obtained.
PRESSURE CONTROL IN BAND - SAW HYDRAULIC SYSTEM USING THE FUZZY LOGIC
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
G. Filo,
2008,
pp. 452-461,
Juli 2008
view abstract
In this work the problem of controlling the pressure in a band-saw hydraulic system during the cutting process is
considered. It is proposed an application of electromagnetically controlled proportional relief valve, which is adapted to cooperation with digital microprocessor control system and fuzzy logic controller. Application of this controller allows for obtaining optimal value of force acting on teeth during the whole cutting process for various shapes of cut material. Model of the system was built using the Matlab-Simulink environment. Then simulations of cutting process were carried out. In simulations were used the following controllers: PID and Fuzzy Logic Controller and the following cross-sections of cut material: triangular, round and tubular.
Pressure control in BOSCH Common Rail injection system
The 20th International Conference on Hydraulics and Pneumatics (ICHP), Prague, Czech Republic
ISBN: 978-80-02-02074-5,
J. Čáp and P. Kremláček,
2008,
pp. 198-205,
September 2008
view abstract
article is focused on the pressure control in BOSCH Common rail (CR) injection system. There are low pressure and high pressure control valve presented and principles of pressure control as well as software functions supporting the pressure control are discussed.
CR system experienced a lot of development stages since it was first introduced in 1997. The first generation, working with pressure up to 135 MPa, was equipped with a high pressure control valve. Further generations are controlled either by low pressure controller or by both low pressure and high pressure controllers to be able to reach and keep the working pressure about 160 Mpa.
CR system consists of high pressure pump, high pressure accumulator (common rail), injectors, several sensors and actuators. Pump delivers compressed fuel into the rail; electronically operated injectors provide injections with minimal quantity of 1mg per injection. Control unit, in combination with high speed injector, is able to split the injection cycle into several pilot-, main-, and post-injections. Better combustion, lower emissions and lower noise is reached by applying isolated injections at high pressure.
Rail pressure is controlled in a closed loop. In the high pressure controlled systems, control unit collects information from all engine sensors (speed, temperatures, pressures, accelerator pedal), defines a pressure level for the further operation and calculates how much fuel it will need for the closest time interval. Subtracting this value from the fuel quantity, delivered into the rail by the pump momentarily, it gets the quantity which should be released form the rail through the high pressure controller. Feedback loop is made by pressure sensor and PID controller which adapts the quantity for the high pressure controller. Such kind of pressure control is very fast, but causes higher stress of the pump.
In the low pressure controlled systems, control unit also collects all signals from engine sensors, calculates pressure and fuel quantity needed for the upcoming time interval. Afterwards, low pressure controller reduces the fuel quantity getting to be compressed by the pump and delivered into the rail. Feedback loop remains the same like for the high pressure control. Low pressure control reduces stress on pump, extends its lifetime, but it is slower.
There was so called “two-governor concept“ developed for high end applications, like e.g. CR systems with piezo-inline injectors. Both pressure controllers are present in the hydraulic circuit. Their function is bounded with engine operation point, mainly with engine speed and injection quantity. This concept is able to solve critical situations, like e.g. fast pressure drop, when the driver’s demand increases or decreases rapidly. In such a case there may occur a pressure peaks or drops in the high pressure circuit, which are successfully eliminated by using both pressure controllers.
Moreover, there are several functions implemented in the software of the control unit which assist by the pressure control. Namely IQA (injector quantity adjustment) which rectifies manufacturing tolerances, FBC (fuel balance control) adjusts injection quantity of every injection to get undisturbed run of the engine, PWC (pressure wave control) compensates pressure waves by shifting pilot injection in time, and ZFC (zero fuel calibration) compensates the fatigue drift of injector.
PRESSURE CONTROL IN DIGITAL HYDRAULICS
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
J. Juhala and M. Pietola,
2008,
pp. 163-173,
Juli 2008
view abstract
The aim of this study is to show, how pressure can be controlled in a hydraulic system, where a traditional proportional control valve is replaced by four DFCUs (Digital Flow Control Unit).
The pressure control is one of the basic control principles, which are not studied so far in the field of Digital
Hydraulics. The background of the work is that valve gearing with current on/off –valve technology of DFCUs
produces relative huge pressure steps. Especially, when the hydraulic fluid volume is small, the effective bulk modulus
is large, discrete time step of control is long, and the pressure difference over the valve is high. The response time of current on/off –valves is approximately 20 ms, which is the main cause of the considerable size of pressure steps.
The methods used in this study, include measurements with the DFCUs, and the cylinder test bench, modeling and
simulation of the DFCU -valve package and analytical work.
The results of the study demonstrate, that Digital Hydraulics can be used to pressure control. The simulation results of
current and next generation DFCUs are demonstrated. Also the requirements of accurate pressure control with Digital
Hydraulics are discussed.
Pressure Distributions in Oil Flim Between the Cylinder Block and Valve Plate in the Piston Pump
Proceedings of the 6th FPNI - PhD Symposium, West Lafayette, USA, June 15-19, 2010
ISBN: 1-932739-15-7,
D. Sochacki and T. Zloto,
2010,
volume 2,
pp. 807-817,
Juni 2010
view abstract
The pressure distribution of oil film at the smallest height of the gap occurring between the valve plate and cylinder
block is given as a function of geometrical and working parameters of the axial piston pump.
The analysis was performed using the finite element method implemented in a computer program developed by the
author of the present paper.
The deformations of valve plate under the action of outlet pressure with the use of ADINA software are also presented.
From the analysis of results it follows that the maximum deformations of valve plate occur
in the radial direction, whereas less significant ones occur in the axial direction.
Pressure, Flow, Force, and Torque Between the Barrel and Port Plate in an Axial Piston Pump
J. M. Bergada and J. Watton and S. Kumar,
In Journal of Dynamic Systems, Measurement, and Control,
2008,
volume 130,
Januar 2008
view abstract
This paper analyzes the pressure distribution, leakage, force, and torque between the barrel and the port plate of an axial piston pump. A detailed set of new equations is developed, which takes into account important parameters such as tilt, clearance and rotational speed, and timing groove. The pressure distribution is derived for different operating conditions, together with a complementary numerical analysis of the original differential equations, specifically written for this application and used to validate the theoretical solutions. An excellent agreement between the two approaches is shown, allowing an explicit analytical insight into barrel/port plate operating characteristics, including consideration of cavitation. The overall mean force and torques over the barrel are evaluated and show that the torque over the XX axis is much smaller than the torque over the YY axis, as deduced from other nonexplicit simulation approaches. A detailed dynamic analysis is then studied, and it is shown that the torque fluctuation over the YY axis is typically 8% of the torque total magnitude. Of particular novelty is the prediction of a double peak in each torque fluctuation resulting from the more exact modeling of the piston/port plate/timing groove pressure distribution characteristic during motion. A comparison between the temporal torque fluctuation pattern and another work shows a good qualitative agreement. Experimental and analytical results for the present study demonstrate that barrel dynamics do contain a component primarily directed by the torque dynamics.
Pressure peak phenomenon in digital hydraulic systems - a theoretical study
Bath Workshop on Power Transmission and Motion Control (PTMC 2005), 7-9 September 2005
A. Laamanen and M. Linjama and M. Vilenius,
2005,
pp. 91-104,
view abstract
This paper studies pressure peak phenomenon in modern on/off control systems based on the PCM control method. In PCM control systems, pressure peaks may occur because several valves are opened and closed simultaneously. In the ideal case, timing happens perfectly but in practice, switching times of the valves vary more or less. Due to this effect, valve or valves are sometimes closed before the next ones open (or vice versa), and a pressure peak occurs. Pressure peaks cause noise, may damage system and motion can be jerky and therefore, pressure peak minimization methods are worth thinking. Fundamental theory of the pressure peak phenomenon is discussed and different solutions to prevent pressure peaks are introduced based on the theory. One interesting option is Fibonacci coding which can be used instead of traditional binary coding in PCM control systems.
Pressure tracking control for a self-energizing hydraulic brake
Power Transmission and Motion Control 2007
ISBN: ISBN: 978-0-86197-140-4,
M. Liermann and C. Stammen and H. Murrenhoff,
2007,
pp. 315-330,
September 2007
view abstract
A new hydraulic brake utilizing a self-energizing effect is developed at the Institute for Fluid Power Drives and Controls (IFAS). Contrary to a conventional hydraulic braking actuator it has no pneumatic or hydraulic power supply. It features a supporting cylinder, which conducts the braking force into the bogie. The braking force pressurizes the fluid in the supporting cylinder and is the power source for pressure control of the actuator. The only interface connection is the electrical braking force reference signal from a superior control unit.
The dynamics of the self-energizing electro-hydraulic brake is open-loop unstable. The ratio of piston areas between supporting cylinder and actuator is such, that an existing braking force causes a higher supporting pressure than is needed to produce the actual normal force. In this paper the hydraulic mechanic brake design is derived from given requirement specifications. A mathematical description of the brake dynamics is presented in combination with a friction coefficient model for more realistic simulations. The closed loop control is developed on the basis of the analytical description of the open loop dynamics.
Principle of Active Vibration Damping Using Pneumatic McKibben Type Muscle Actuator
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
P. Keski-Honkola and J. Kajaste and M. Pietola,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 183-194,
März 2010
view abstract
McKibben type pneumatic muscle actuator (PMA) produces force as a function of contraction and pressure. However if PMA is used for active damping then displacements are also minimal and muscle force is proportional only to the control pressure. The advantages of pneumatic muscles are demand of only small amount of air, force capacity and practically stick-slip free operation. The target of this study is to investigate experimentally the features and limitations of the use of pneumatic muscle as an actuator in active vibration control of a steel beam. Active vibration cancellation strategy was applied and the PMA was used to produce counter-force to minimize the oscillation amplitude at the selected frequency. Two different kinds of control valve configuration cases are discussed. Both configurations successfully cancelled low frequency vibrations but proportional valve was working near its limit. On/off valve could easily cope with damping but had some other challenges.
Probability Density Function of Underwater Bomb Trajectory Deviation Due to Stochastic Ocean Surface Slope
Peter C. Chu and Chenwu Fan,
In Journal of Dynamic Systems, Measurement, and Control,
2011,
volume 133,
Mai 2011
view abstract
Ocean wave propagation causes random change in an ocean surface slope and in turn affects the underwater bomb trajectory deviation (r) through a water column. This trajectory deviation is crucial for the clearance of obstacles such as sea mines or a maritime improvised explosive device in coastal oceans using bombs. A nonlinear six degrees of freedom (6DOF) model has been recently developed and verified at the Naval Postgraduate School with various surface impact speeds and surface slopes as model inputs. The surface slope (s) randomly changes between 0 and pi/2 with a probability density function (PDF) p(s), called the s-PDF. After s is discretized into I intervals by s1,s2,…,si,…,sI+1, the 6DOF model is integrated with a given surface impact speed (v0) and each slope si to get bomb trajectory deviation r^i at depth (h) as a model output. The calculated series of {r^i} is re-arranged into monotonically increasing order (rj}. The bomb trajectory deviation r within (rj, rj+1) may correspond to one interval or several intervals of s. The probability of r falling into (rj, rj+1) can be obtained from the probability of s and in turn the PDF of r, called the r-PDF. Change in the r-PDF versus features of the s-PDF, water depth, and surface impact speed is also investigated.
PROBLEMS OF THE ADAPTIVE CONTROL FOR ELECTRO – HYDRAULIC SERVO - SYSTEM
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
P. Wos and R. Dindorf,
2008,
pp. 153-162,
Juli 2008
view abstract
The paper deals with the structure and the drive of the adaptive electro-hydraulic control system and practical
verification of the identification and control algorithms. The author discusses the electro-hydraulic servo system
composed of the plumbing servomotor steered with flow distributor. It is a strongly non-linear, object with parameters
changing in time. The parameters of the adaptive adjuster were determined by means of the results of the current
identification of the parametric model. The identification was conducted on the basis of the measurement of the object’s
controlling size and the regulated size of the object. The identified model of the object was applied to carry out on-line
synthesis of the PID adjuster. The selected problems connected with obtaining the algorithm of adaptive control were
presented. The computer program implementing the algorithm with the numerical simulation and the identification of
the physical model of the control object were worked out. The aim of the research was to examine the effectiveness of
adaptive control method in electro-hydraulic servo systems both theoretically and experimentally.
ProChain – A Revolving Drive, Energy and Data System Based on a Block Chain
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
Polman, Eckhard,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 211-222,
März 2010
view abstract
The requirements for this product initially came from the automobile industry. There are so-called “accumulation bridge" that move steelplates first horizontally, then in suspended transport via magnetic belt conveyors to subsequently abandon them onto a lifter table for stacking. The increasing use of aluminium plates justifies the need for a vacuum conveyor system. This was the reason to design
ProChain, a completely new conveyor system for fixed transport of goods of various type, design and size.
I managed to design a whole new system that inducts energy and data in terms of electricity and compressed air into a constantly revolving chain system. This is a practically fail-safe and worldwide unique system that makes it possible to grip the energy at any spot and switch it on and off selectively via actuators. An aluminium plate (as well as other materials) can therefore be transported and selectively
operated by vacuum units with cupping vessels. The result is a continously fixed transport with an intelligent operating system that avoids unloaded returns which is a disadvantage of linear axes.
PROGRESS OF THE ON-LINE MONITORING OF THE HYDRAULIC SYSTEMS OF A HOT STEEL STRIP ROLLING MILL
Proceedings of the 1st FPNI PhD Symposium, Hamburg, Germany, September 20–22, 2000
ISBN: 3-00-006510-5,
S. Bailey and J. Watton,
2000,
pp. 203-213,
September 2000
view abstract
This paper outlines the research profile for the first 18 months of a Fluid Power based PhD programme. The
paper illustrates the typical pattern of study that has been adopted by previous PhD students within this subject
area. The recent development of an on-line condition monitoring system for a hot rolling finishing mill has been
outlined. This previous work has seen the installation of an on-line condition monitoring system for two of the
three major hydraulic control systems, lending this project to concentrate on the development of a fault diagnostic
tool for the Automatic Gauge Control system. This paper emphasises the need to undertake comprehensive
background work in order to understand fully the many disciplines related to Fluid Power, Artificial Intelligence,
and their applications. Initial stages of development have begun, with a fault diagnostic tool created for a
computer-based simulation of a pressure-controlled hydraulic test rig. The laboratory based test rig incorporates
a hydraulic transmission line, as present on the hydraulic control systems of the finishing mill. Simulation
results are then used in conjunction with an Artificial Neural Network to create a fault diagnostic tool, the first
stages of the on-line condition monitoring system for the AGC system.
Proportional Technology with Electronics on Board
The Tenth Scandinavian International Conference on Fluid Power, SICFP'07, Tampere, Finland, May 21-23, 2007
ISBN: 978-952-15-1760-0,
M. Emmaneel,
2007,
volume 3,
pp. 411-418,
Mai 2007
view abstract
Continuously increasing economic requirements have made it necessary to develop new parts for proportional valve technology. The same economic pressures have resulted in shorter delivery times and less time allowed for the installation of new equipment. The time for replacement, fitting, configuration and commissioning of components, and in this particular case of proportional valves, is now at a critical minimum. It was therefore necessary to look at improving certain individual design aspects of these valves in order to simplify and accelerate this procedure. The result is a new proportional valve tech-nology incorporating on board electronics, a feature requested for some time now by our industrial clients.
A second issue, especially evident in recent years, is the continued rise in system oper-ating pressures, leading automatically to higher flow rates. To avoid the wear problems unavoidably associated with these higher flow rates, the use of new materials for water-hydraulic systems and valves has been indispensable. In this regard Tiefenbach Wasser-hydraulik GmbH tests any relevant new materials almost as soon as they become avail-able to the engineering industry. Great importance is placed on achieving a compromise between the properties of these new materials, their cost and their practicality in the harsh environment of water hydraulics. With this article we also hope to show our ex-perience with some of these materials.
Proportional Valves in Low-pressure Water Hydraulics
Proceedings of the 3rd FPNI - PhD Symposium on Fluid Power, Terrassa, Spain, June 30 - July 2, 2004
ISBN: 84-609-1354-6,
H. Sairiala and K. T. Koskinen and M. Vilenius,
2004,
pp. 501-508,
Juni 2004
view abstract
The research in the field of proportional valves in water hydraulics is quite new. The purpose of this study
is to summarize the state of the current component technology and to show some control results that can
be achieved with proportional valves in low-pressure water hydraulics. This paper presents two
proportional directional valves that can be used in low-pressure water hydraulics. The main
characteristics of the valves are shown and both valves will be used in position control of a cylinder drive.
The results show that current water hydraulic proportional valves have quite good characteristics and that
good position control results can be achieved with them.
PROPOSAL OF A NEW BOND-GRAPH METHOD FOR MODELLING PNEUMATIC SYSTEMS
Y. Sakurai and K. Takahashi,
In International Journal of Fluid Power,
2004,
volume 5,
pp. 17-22,
März 2004
view abstract
This paper proposes a new bond-graph method for modelling pneumatic systems, which have compressible fluidflow
and thermal fields. In constructing bond-graph models for such systems, fluid and thermal power bonds have been
employed. Furthermore, multi-port C and multi-port R elements have been used. Therefore, the resulting bond-graph
models become complicated, and it is difficult to understand how energy flows branch off or join together. From these
viewpoints, a new bond-graph method for modelling such systems is proposed in the present study by introducing a
new concept of effort and flow applied to both compressible fluid-flow and thermal fields. In this bond-graph method,
the product of effort and flow is power, which means that the true bond-graph is employed. Furthermore, 1-port C and
1-port R elements are used for modelling. Therefore, the energy flows can be easily understood from the resulting
bond-graph. A simulation example is shown to confirm the usefulness of the proposed bond-graph method.
Providing Stability of Pressure Control Valve by Compensator
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-90-7,
A. Gimadiev and V. Sverbilov and E. Shakhmatov,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 1,
pp. 247-260,
März 2010
view abstract
Dynamic processes, noise and vibration in a hydraulic system provoke self-exited oscillations of control valves that add more energy in the circuit. For this case one of effective means of decreasing pressure/flow fluctuation and stabilizing hydraulic control system is a corrective device (compensator).
Being installed in the pipe system it provides absorption of oscillatory energy and breaks feedbacks in oscillatory circuits. The paper is devoted to design issues of acoustic RL – filter as effective compensator for stabilizing control system. On the base of research of control valve interaction with pipelines stability criteria were derived. Efficiency of the offered decision for suppressing self-exited oscillation in fuel system of gas turbine engine was confirmed by experimental research.
PSEUDO - DYNAMIC SOLUTION OF PRESSURES IN SMALL VOLUMES IN FLUID POWER CIRCUIT SIMULATION
Proceedings of the 5th FPNI PhD Symposium, Cracow, Poland, 1-5 July 2008
ISBN: 978-83-7242-474-7,
R. Åman and H. HANDROOS,
2008,
pp. 409-417,
Juli 2008
view abstract
The integration of pressures in small fluid volumes causes numerical problems in fluid power circuit simulation. The
system stiffness approaches infinity as the fluid volume approaches zero. If fixed step ODE-algorithms are used the
stability would easily be lost when integrating pressures in small volumes. In case of using variable step algorithm the
step size is decreasing into its minimum as the fluid volume decreases towards zero. This results in very long simulation
times. To solve the problem caused by small fluid volumes the present paper proposes a pseudo-dynamic solver that
instead of integrating the pressure in small volume solve the pressure as a static pressure at each time step by using
pseudo-dynamic solver. The pressures in small volumes are solved as static solution while the main integration loop is
stopped. Numerically efficient parameter values to all small volumes (like one litre) are given and their steady-state
pressures are solved by numerical integration. After obtaining the pressures in small volume the next integration step is
executed in the main loop. The key advantage of the novel method is that the numerical problems caused by the small
volumes are completely avoided. The present paper describes the algorithm in general level and how it applies to a
simple circuit composed of two orifices and two fluid volumes. The results obtained by the pseudo-dynamic method is
compared with those obtained by conventional Runge-Kutta method. The dependency of calculation speed on the
integrator time step and selected tolerance of pseudo-loop iteration is also investigated.
PSH Press Drive Servo Hybrid- Servo Pump Drive System for Hydraulic Presses
7th International Fluid Power Conference: Workshop Proceedings, Aachen, Germany, 22-24 March 2010
ISBN: ISBN: 978-3-940565-93-8,
S. Mann and W. Kuttruf,
Apprimus Verlag, Aachen,
ed. Murrenhoff, Hubertus,
2010,
volume 4,
pp. 189-200,
März 2010
view abstract
A new drive solution for hydraulic presses is described. The system is characterized by a simple and ro
