Research On Fuzzy Sliding Mode Control Of Pump Control Electro-hydraulic Position Servo System Based On Directional Valve

At present,in the field of hydraulic control,there are two control modes according to different control components,namely,a valve control system controlled by a servo flow valve and a pump control system driven by a servo motor.However,these two systems have inevitable defects.For example,the valve control system is sensitive to oil pollution,low efficiency,the system overflow loss will increase the system temperature,and the heat is difficult to dissipate;the pump control system has a longer response time.The control accuracy is low.In order to solve these problems,this paper proposes the use of PLC as the control system,the positioning control design of the hydraulic cylinder,the electromagnetic reversing valve and the one-way quantitative pump are used for cooperative control,and the one-way quantitative pump is driven by the servo motor,and the electromagnetic reversing valve is used.The hydraulic cylinder is reversing.In this paper,for the problem that electro-hydraulic servo system is difficult to accurately model,the system is divided into four modules by using the idea of block modeling.The transfer function model is established for each module by analytical method,and the nonlinear link is appropriate.Assumptions and simplifications.Then,the modules are aggregated and the mathematical model of the system is established.The system model is discretized for the convenience of later calculation,and the discrete system is simulated and analyzed.The system specifically expounds the PID control theory,and writes the PID algorithm simulation program on MATLAB software.At the same time,the step response,sinusoidal response and square wave response of the system under different PID parameters are simulated and analyzed.Through simulation analysis,the following conclusions are obtained:the difference of PID parameters has different influence on the response characteristics of the system,and under the control of ordinary PID,the system will cause excessive overshoot of the system while ensuring rapid response.However,when the small steady-state error and stability are guaranteed,the system response speed is greatly reduced.Since the electro-hydraulic servo system itself has many inherent problems,such as uncertain hysteresis,time-varying,and nonlinearity.In order to solve the problems of the system itself,a fuzzy sliding mode controller is proposed to study the system.According to the system control requirements,the sliding mode control and fuzzy sliding mode control program are programmed in MATLAB/Simulink,and the dynamic response characteristics of the system are carried out.The simulation analysis shows that the fuzzy sliding mode control improves the dynamic response characteristics of the system.Based on the CQYZ-D experimental control platform,the system hydraulic circuit is built.The PID controller and fuzzy sliding mode controller of the pump-controlled electro-hydraulic servo position system based on the reversing valve are developed on Lab VIEW software.The experimental research on common PID control,sliding mode control and fuzzy sliding mode control of electro-hydraulic position servo system is carried out.At the same time,the step response,sinusoidal response and square wave response experimental results of the system under different control methods are analyzed.The following conclusions are obtained:the system has large steady-state error,long adjustment time and response speed when using PID control.The slow and hysteresis phenomenon is obvious.Under the sliding mode control,the system has obvious chattering and overshooting phenomenon.Compared with the ordinary PID and sliding mode control,the fuzzy sliding mode control eliminates the jitter phenomenon of the system,and there is almost no oscillation after stabilization.There is almost no hysteresis in the sinusoidal tracking process.