# NEW RESULTS IN CONTROL SYNTHESIS FOR ELECTROHYDRAULIC SERVOS

## Keywords:

electrohydraulic servo, robust linear control, control saturation, antiwindup compensation, fuzzy supervised neurocontrol, backstepping control, numerical simulation## 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.

### Downloads

## References

Åström, K. J. and Wittenmark, B. 1974. Computer

controlled systems. Theory and design. Prentice-

Hall, Englewood Cliffs, NJ.

Blackburn, J. E., Shearer, J. L. and Reethof, G.

Fluid power control. Tech. Press of Massachusetts

Institute of Technology and Wiley, New

York.

Bobrow, J. E. and Lum, K. 1996. Adaptive, high

band-width control of a hydraulic actuator, Transactions

of the ASME, Journal of Dynamic Systems,

Measurements and Control, 118, December, pp.

–720.

Davison, E. J. and Goldenberg, A. 1975. Robust control

of a general servomechanism problem: the servocompensator.

Automatica, 11, pp. 461-471.

Davison, E. J. 1976. The robust control of a servomechanism

problem for linear time-invariant multivariable

system. IEEE Transactions on Automatic

Control, 21, pp. 25-34.

Ermakov, S. A., Klaptsova, T. S. and Smirnov,

G. G. 1986. Synthesis of electrohydraulic tracking

systems with observers (in Russian), Pnevmatika i

Gidravlika. 12, Moskow, Mashinostroenie, pp. 45–

Frankena , J. F. and Sivan , R. 1979. A nonlinear optimal

control law for linear systems. International

Journal of Control, 30, pp. 159-178.Ghazi Zadeh, A., Fahim, A. M. and El-Gindy, M.

Neural network and fuzzy logic applications

to vehicle systems: literature survey. International

Journal of Vehicle Design, 18, pp. 132-193.

Hahn, H., Piepenbrink, A. and Leimbach, K.-D.

Input-output linearization control of an electro

servohydraulic actuator. Proceeding of 3rd IEEE

Conference on Control Applications, Glasgow, pp.

-1000.

Halanay, A., Safta, C. A., Ursu, I. and Ursu, F. 2004.

Stability of equilibria in a four–dimensional nonlinear

model of a hydraulic servomechanism. Journal

of Engineering Mathematics, 49, pp. 391–406.

Han, J. 1989. Control theory: it is a theory of model or

control? Systems Science and Mathematical Sciences,

, pp. 328–335.

Hanus, R., Kinnaert, M. and Henrotte, J.-L. 1987.

Conditioning technique: a general antiwindup and

bumpless transfer method. Automatica, 23, pp. 729-

Ingenbleek, R. and Schwarz, H. 1993. A nonlinear

discrete-time observer based control scheme and its

application to hydraulic drives. Proceedings of 2nd

European Control Conference, Groningen, the

Netherlands, July, pp. 215–219.

Jelali, M. and Schwarz, H. 1995. Continuos-time identification

of hydraulic servo-drive nonlinear models.

Proceedings of 3rd European Control Conference,

, Rome, Italy, pp. 1545-1549.

Jelali, M. and Kroll, A. 2003. Hydraulic servosystems.

Springer Verlag, Berlin.

Kliffken, M. G. 1997 Robust sampled-data control of

hydraulic flight control actuators, 5th Scandinavian

International Conference on Fluid Power,

SICFP’97, Linköping, Sweden, May 28-30.

Krikelis, N. J. and Barkas, S. K. 1984, Design of

tracking systems subject to actuator saturation. International

Journal of Control, 39, 4, pp. 667-682.

Krstić, M., Kanellakopoulos, I. and Kokotović, P.

Nonlinear and adaptive control design, Wiley

and Sons, New York.

Mihajlov, M., Nikolić, V. and Antić, D. 2002. Position

control of an electro-hydraulic servo system using

sliding mode control enhanced by fuzzy PI controller.

Facta Universitas. Series: Mechanical Engineering,

, pp. 1217-1230.

Panasian, H. V. 1986. Reduced order observers applied

to state and parameter estimation of hydromechanical

servoactuators. Journal of Guidance,

Control and Dynamics, 9, pp. 249–251.

Park, J. K. and Choi, C.-H. 1993. A compensation

method for improving the performance of multi

variable control systems with saturating actuators.

Control-Theory and Advanced Technology, 9, pp.

-322.

Plummer, A. R. 1997. Feedback linearization for acceleration

control of electrohydraulic actuators.

Proceedings of the Institution of Mechanical Engineers,

, Part 1, pp. 395–406.

Richard, E. and Outbib, R. 1995. Feedback stabilization

of an electrohydraulic system. Proceedings of

rd European Control Conference, Rome, Italy,

September, pp. 330–334.

Sepulchre, R., Janković, M. and Kokotović, P. 1997.

Constructive nonlinear control, Springer-Verlag,

London.

Tyan, F. and Bernstein, S. 1994. Antiwindup compensator

synthesis for systems with saturating actuators.

Proc. of 33rd Conference on Decision and Control,

Lake Buena Vista, FL, pp. 150-155.

Tzes, A. and Peng, P.-Y. 1997. Fuzzy neural network

control for DC-motor micromaneuvering. Transactions

of the ASME, Journal of Dynamic Systems,

Measurement and Control, 119, pp. 312-315.

Ursu, I. 1984. Theoretical and experimental data concerning

qualification testing and flight clearance for

aircraft servomechanism SMHR. National Institute

for Scientific and Technical Creation – INCREST

Report, N-5303, Bucharest.

Ursu, I., Popescu, F., Vladimirescu, M. and Costin,

R. 1994. On some linearization methods of the generalized

flow rate characteristic of the hydraulic

servomechanism. Revue Roumaine des Sciences

Technique, Série de Mécanique Appliquée, 39, pp.

-217.

Ursu, I., Vladimirescu, M. and Ursu, F. 1996. About

aeroservoelasticity criteria for electrohydraulic

servo-mechanisms synthesis. Proceedings of ICAS’

, Sorrento, Italy, pp. 2335-2344.

Ursu, I., Tecuceanu, G., Ursu, F., Sireteanu, T. and

Vladimirescu, M. 1998. Aircraft Engineering and

Aerospace Technology, 70, 4, pp. 259–264.

Ursu, I., Ursu F., Sireteanu, T. and Stammers, C. W.

Artificial intelligence based synthesis of

semiactive suspension systems. Shock and Vibration

Digest, 32, pp. 3-10.

Ursu, I., Ursu, F. and Iorga, L. 2001. Neuro-fuzzy

synthesis of flight controls electrohydraulic servo.

Aircraft Engineering and Aerospace Technology,

, pp. 465-471.

Ursu, F. and Ursu, I. 2001. Robust synthesis with antiwindup

compensation for electrohydraulic servoactuating

primary flight controls. Preprints of the

th IFAC Symposium on Automatic Control in

Aerospace, Bologna-Forli, September, 2−7, pp.

-202.Ursu, I. and Ursu, F. 2002. Active and semiactive control.

Romanian Academy Publishing House, Bucharest.

Ursu, I. and Popescu, F. 2003. Nonlinear control synthesis

for position and force electrohydraulic servos.

Proceedings of the Romanian Academy, Series A, 4,

, pp. 115–120.

Vemuri, V. 1993. Artificial neural networks in control

applications. In Advances in Computers, edited by

M. C. Yovits, Academic Press, 36, pp. 203-332.

Vossoughi, G. and Donath, M. 1995. Dynamic feedback

linearization for electrohydraulically actuated

control systems. Transactions of the ASME, Journal

of Dynamic Systems, Measurements and Control,

, December, pp. 468–477.

Zhou, K. Doyle, J. K. and Glover, K. 1996. Robust

and optimal control, Prentice Hall, New Jersey.

Yen, J., Langari, R. and Zadeh, L. A. Eds. 1995. Industrial

applications of fuzzy control and intelligent

systems. New York, IEEE Press.

Wang, L. 1994. Adaptive fuzzy systems and control −

design and stability analysis, Englewood Cliffs,

New Jersey, Prentice Hall.

Wang, P. K. C. 1963. Analytical design of electrohydraulic

servomechanism with near time-optimal response.

IEEE Transactions on Automatic Control

AC-8, pp. 15-27.

Wang, L-X. and Kong, H. 1994. Combining mathematical

model and heuristics into controllers: an

adaptive fuzzy control approach. Proceedings of the

rd IEEE Conference on Decision and Control,

Buena Vista, Florida, December 14-16, 4, pp. 4122-