Design And Online Realization Of Advanced Fuzzy Controller Of Electro-hydraulic Position Servo System

As an important component of electromechanical control system, Electro hydraulic position servo system which has some characteristics of high control precision, speed response and great output power, is widely used in various technical fields of industry. However, there are so many typical problems such as time- varied parameters, outside disturbance and the nonlinear dead zone of the valve existing in the electro-hydraulic position servo system that it must take certain adjustment measures in practical application. Therefore, study on the control method of electro-hydraulic position servo system has great practical value and theoretical significance.At first, the status and development of electro-hydraulic servo system and its control method both home and abroad at present are discussed in the paper. And then, on the basis of fluid mechanics and classical control theory, the mathematical model of electro-hydraulic position servo system with asymmetry cylinder controlled by symmetry valve is set up, in succession, the affect on valve's flow of hydraulic cylinder's asymmetry is discussed and the affect of the dynamic and static characteristics and parameter on the system are analyzed in detail.In view of the speed response requirement and the parameter time-variation of electro-hydraulic position servo system, the PID controller and the fuzzy controller are designed respectively. The simulation shows that PID control has high precise of steady-state, but the adaptive ability of parameter variation is poor. And fuzzy control can be well adapted to parameter variation while the steady-state error is inevitable. Therefore, the proportion-fuzzy PID control method is put forward. The simulation result of proportion-fuzzy PID control shows that it increases the response velocity of system, and ensures sufficient robustness at the same time.In this thesis, the realization of PID control, fuzzy control and proportion- fuzzy PID control in RTW is introduced in detailed that controllers designed in Simulink enable to be tested in practical system. Through the real-time simulation technique of real-time workshop (RTW), three types of controller are experimentally validated on the test-bed. Experiment results show that the proportion-fuzzy PID control ensures the Electro-hydraulic position servo system to work steadily and track rapidly. Moreover, its ability of adapting to parameter variation is superior to the other two controllers.