Fuzzy Control And Experimental Research On Multipurpose Electro-hydraulic Servo System

The control methods of the electro-hydraulic servo test bench, which is developed by the Harbin Xingong Hydraulic System Engineering Co., Ltd., are mainly studied in this thesis. The mathematical models are uncertain for the nonlinearity of the electro-hydraulic servo system and the changeability of the parameters. Moreover, the loading system is complex itself and there always exists external disturbance during operation. In view of all these factors, the linear PID controller is limited in the ability to improve the tracking performance. However, the fuzzy logic controller (FLC) appears particularly useful in cases where the available sources of information are inexact or uncertain, which has stronger adaptability to the procedure parameters'variations. Therefore, adopting the fuzzy controller to controlling the electro-hydraulic position servo system has great practical significance and theoretical value.In this thesis, the electro-hydraulic servo system controlled by the computer is analyzed at first and the simplified mathematical model is set up. A fuzzy controller is developed based on the uncertainties of the hydraulic system, which performs well on suppressing the error caused by the disturbance. To make the controller better, a hybrid fuzzy PID controller is proposed, which not only inherits the rapidity and stability of the fuzzy controller, but also guarantee the high precision of the PID controller. Additionally, a new switching mode based on fuzzy rules is designed to avoid the choice of the switching point and disturbances caused by the switchover between the two control methods. And in the fuzzy controller on-line interpolation of the self-tuning gene fuzzy model is employed to improve the self-adjusting abilities of the control rules. Proved by the simulation and experiments, the modified hybrid fuzzy-PID controller can resolve the mild agitation around the steady-state of the traditional fuzzy controller. It is portable, robust and satisfiable for the control of the electro-...