A. A. ALY75

(a)

(b)

(c)

Figure 10. (a) The angular motor shaft position of sin wave

reference input; (b) GPID controller output; (c) Servovalve

flow rate.

5. Conclusions

This paper presents an optimization method of PID con-

trol parameters for the position control of nonlinear elec-

trohydraulic servosystem by GA as a search technique

with minimum information specific to the system such as

the defined fitness function.

From the results, it is demonstrated that the optimized

PID improve the performances of the hydraulic servo-

system in order to achieve minimum settling time with

no overshoot and nearly zero steady state error. The re-

ciprocal of ITAE criterion is modified to be an appropri-

ate fitness function for GA to evaluate the control per-

formance of the given feedback gains. A disadvantage of

the proposed method is the necessity of the definition of

parameters for a performance index by the user, which

impedes the procedure to be fully automatic. It seems to

be easy to adapt the method presented here to tune other

controller types, where some optimization is involved,

such LQR, LQG or pole placement controllers, when

weighting parameters or weighting functions can be

searched.

6. References

[1] H. E. Merrit, “Hydraulic Control Systems,” John Wiley

& Sons Inc, New York, 1967.

[2] J. Watton, “Fluid Power Systems,” Prentice Hall, New

Jersey, 1989.

[3] J. E. Bobrow and K. Lum, “Adaptive, High Bandwidth

Control of a Hydraulic Actuator,” Journal of Dynamic

Systems, Measurement and Control, Transactions of the

ASME, Vol. 118, No. 4, 1996, pp. 714-720.

doi:10.1115/1.2802347

[4] T. L. Chern and Y. C. Wu, “Design of Integral Variable

Structure Controller and Application to Electrohydraulic

Velocity Servosystems,” IEEE Proceedings D, Vol. 138,

No. 5, 1991, pp. 439-444.

[5] R.-F. Fung and R.-T. Yang, “Application of Variable

Structure Controller in Position Control of a Nonlinear

Electrohydraulic Servo System,” Computers & Structures,

Vol. 66, No. 4, 1998, pp. 365-372.

doi:10.1016/S0045-7949(97)00084-9

[6] G. Vossoughi and M. Donath, “Dynamic Feedback Lin-

earization for Electrohydraulic Actuated Control Sys-

tems,” Journal of Dynamic Systems, Measurement and

Control, Transactions of the ASME, Vol. 117, No. 3,

1995, pp. 468-477. doi:10.1115/1.2801102

[7] A. A. Aly, “Modeling and Control of an Elec-

tro-Hydraulic Servo Motor Applying Velocity Feedback

Control Strategy,” International Mechanical Engineering

Conference, IMEC2004, Kuwait, 2004.

[8] A. H. Jones and M. L. Tatnall, “Online Frequency Do-

main Identification for Genetic Tuning of PI Controllers,”

Proceedings of ICSE, Coventry University, Coventry,

1994.

[9] “Moog 761 Series Servovalves,” Moog Controls Inc.,

East Aurora.

[10] W. Wang, J. T. Zhang and T. Y. A. Chai, “Survey of

Advanced PID Parameter Tuning Methods,” Acta Auto-

matica, Vol. 26, No. 3, 2000, pp. 347-355.

[11] M. H. Moradi, “New Techniques for PID Controller De-

sign,” IEEE Conference on Control Applications, Vol. 2,

2003, pp. 903-908.

[12] A. A. Aly, “A Non Linear Optimal PID Control of a Hy-

draulic Crane,” Journal of Engineering Science, Vol. 33,

No. 1, 2007, pp. 199-209.

[13] K. K. Tan, S. N. Huang and T. H. Lee, “Development of

a GPC-based PID Controller for Unstable Systems with

Dead Time,” ISA Transactions, Vol. 39, 2000, pp. 57-70.

doi:10.1016/S0019-0578(99)00036-1

[14] P. Cominos and N. Munro, “PID Controllers: Recent

Tuning Methods and Design to Specification,” IEE Pro-

ceedings Control Theory & Applications, Vol. 149, No. I,

January 2002.

[15] J. G. Ziegler and N. B. Nichols, “Optimum Settings for

Automatic Controllers,” Transactions of the ASME, Vol.

64, 1942, pp. 759-768.

[16] C. Coon, “Theoretical Consideration of Retarded Con-

trol,” Transactions of the ASME, Vol. 75, 1952, pp.

827-834.

[17] L. Hao, C. L. Ma and F. Li, “Study of Adaptive PID Con-

Copyright © 2011 SciRes. ICA