Study of Performance Evaluation of Robust Control for Electrical Hydraulic Servo System (2nd Report)

Experimental Comparisons with Several Parameter Variations

Abstract

Hydraulic control systems are used in most industries where heavy objects are manipulated or large forces are exerted on their surroundings. Recently, a positioning control of electrical hydraulic servo system is been applying a robust control theory which is strong for parameter variations or nonlinear elements, instead of as usual a PID control used in widely industries. The purpose of this research is to evaluate several robust control performances and investigate their aptitude for the oil hydraulic system.
In the first paper, we proposed several evaluation methods and standard of designs considering a characteristic of the electrical hydraulic system, and decided system parameters for three kinds of robust control systems which are a Disturbance Observer, a Sliding Mode Control (SMC) and a H_∞ control, according to the several standard of designs. Next, we applied them to the actual electrical hydraulic servo system, and evaluated the difference of the control performance from the point of view of a robustness for load variations as the parameter variations, a characteristic of disturbance cancellation and a control input.
In this paper, the control performance of the robust control systems is evaluated, when they are applied to the positioning control of the electrical hydraulic servo system included of the several parameter variations or the nonlinear elements, which are not only the load variations, but also a oil temperature variations, a pressure variations, and a desired value variations. As a result, all of them have shown good robustness in the load variations, the oil temperature variations, the pressure variations. but the H_∞ control has shown better performance in the desired value variations than other control systems. Further, the SMC has shown good performance in the control input, because it has been smaller than other control systems in the control input.