Research On Control System Of Electro-hydraulic Actuato

With the development of electric transmission technology and hydraulic transmission technology,a kind of electric hydraulic actuator(EHA)is gradually applied in engineering industry.EHA is a combination of electric drive(easy to achieve automatic control,fast signal transmission speed)and hydraulic drive(high output power,flexible layout)electric pump control actuator.Widely used in aerospace,military equipment,ships,active suspension,engineering machinery and other fields.Taking the EHA system as the research object,aiming at the problems of slow dynamic response and low control accuracy,the control algorithm,dynamic characteristics,output flow and pressure characteristics of the system are studied in this paper.The main elements are as follows:(1)The basic composition structure of electro-hydraulic actuator and the function of each component of the system are analyzed.The working process of the system and the fourquadrant working condition of the EHA motor speed EHA hydraulic subsystem are studied.(2)For the speed control subsystem of EHA motor,a permanent magnet synchronous motor(PMSM)is selected as the driving motor and the a-b-cα-β-d-q coordinate system i＿implements the motor speed closed-loop control using vector control method of d = 0.For the EHA hydraulic subsystem,the mathematical model of the hydraulic subsystem is established according to flow continuity equation and force balance equation equation.Based on this,a closed-loop feedback mathematical model of electro-hydraulic actuator position control system is established,and the dynamic response characteristics and output stability of the system are obtained by numerical solution from time domain and frequency domain.(3)According to the position control of the system,the control algorithm is designed.Because the traditional PID control algorithm is difficult to obtain ideal control accuracy,rapid response and robustness,the differential evolution algorithm(DE is applied to the traditional PID control.The generalized reverse learning strategy,adaptive mutation strategy and population generation jump strategy are used to improve the de algorithm to obtain the improved differential evolution PID control algorithm(IGODE-PID).Through numerical simulation,the control effect of traditional PID control algorithm and IGODE-PID control algorithm is compared and analyzed.The results show that the control algorithm can significantly improve the response speed,control precision and robustness of the system.(4)Aiming at the nonlinear characteristics of electro-hydraulic actuator system,the simulation model of EHA hydraulic subsystem was established by AMESim,and vector control model and control algorithm model of EHA motor speed regulation subsystem were established by Simulink.The system is simulated by MATLAB and AMESim,and the position characteristics of the system under variable input signal and variable load are studied.The simulation results show that the control algorithm is effective and good robustness.(5)In order to obtain the effect of load variation on system pressure and flow characteristics,the pressure and flow characteristics of a four-quadrant the electro-hydraulic actuator system operating under constant and variable load conditions are analyzed.The results show that the change of load has a great influence on the pressure characteristics of the system,but has little influence on the flow characteristics of the system and the velocity of the hydraulic cylinder.The results show that the system still has good dynamic performance and robustness under different load conditions.