The application of fuzzy control strategy in electro-hydraulic servo system

In this paper, a detailed discussion of the design of fuzzy controllers for electro-hydraulic servo system is presented from the viewpoint of industrial application and implementation. Since the hydraulic control systems always have the high nonlinearity and uncertain dynamics, the simple linear or nonlinear differential equations can not sufficiently represent corresponding practical system. And therefore many conventional control methods based on mathematical models are limited in their ability to improve the tracking performance, especially in case that the parameters of the system change. The main purpose of this study is the attempt to develop nonlinear fuzzy PID controllers, which greatly improve the robustness, the dynamic and static properties of the system. The proposed fuzzy controllers show excellent robustness against variations of system parameters and external disturbances through a series of simulation studies. Finally, by experiments on a nonlinear electro-hydraulic servo test bench, the effectiveness of this control scheme is verified by comparison with a PID and a fixed fuzzy control.