| Electro-hydraulic servo system is widely used in industry because of its high power density and fast response speed.The electro-hydraulic servo system can be divided into valve control system and pump control system.At present,the valve control system used in most occasions has the problems of low energy efficiency and serious heating due to the throttling loss of the servo valve.Therefore,a new system,pump controlled electro-hydraulic servo system,is proposed.Pump controlled electro-hydraulic servo system is divided into variable displacement pump control system and variable speed pump control system.The variable speed pump control system studied in this paper is a two-way quantitative pump driven directly by the servo motor to provide flow to the actuator,so it fundamentally eliminates the throttling loss and has high energy efficiency.In view of the current traditional PID control can not meet the control effect of the pump controlled electro-hydraulic servo system under the condition of parameter uncertainty and external load disturbance,this paper mainly studies the high-performance sliding mode control method of the pump controlled electro-hydraulic servo system to improve the control performance of the system.In this paper,the mathematical model of the pump controlled electrohydraulic servo system is established.Aiming at the uncertainty of the system parameters and the external interference force,the traditional PID control is difficult to achieve the ideal control effect.For this reason,the sliding mode controller based on the approach law and the backstep sliding mode controller are designed respectively,and the Lyapunov function is constructed to prove the stability of the system.Then a joint simulation model of MATLAB / Simulink and AMESim is built.The simulation results show that the designed controller improves the control accuracy and robustness of the system compared with PID controller,and the performance of the backstep sliding mode controller is better than the sliding mode controller based on the approach law.In order to simplify the controller design of the pump controlled electrohydraulic servo system and make it easier to be applied in engineering,the mathematical model of the original system is reduced reasonably based on the singular disturbance theory.Then,a sliding mode controller based on the extended state observer is designed for the reduced order system.The joint simulation results show that the designed extended observer can accurately estimate the disturbance,and the position tracking accuracy of the designed controller is significantly better than that of PID controller and sliding mode controller without observer.Moreover,it has strong robustness to external disturbance and improves the pump controlled electro-hydraulic servo system control performance.In order to solve the problem that the unknown term in the mathematical model of the pump controlled electro-hydraulic servo system makes the controller design difficult,the RBF neural network is used to approach the unknown term first,then the sliding mode controller based on the RBF neural network is designed,and the Lyapunov function is constructed to prove the stability of the system.The simulation results show that the RBF neural network can approach the unknown items in the system model accurately.Compared with PID controller,the designed controller shows good tracking accuracy and robustness when tracking step position command and sine position command.Four kinds of sliding mode control methods of the pump controlled electro-hydraulic servo system designed in this paper are simulated and compared,and the control accuracy and robustness of these four control methods are analyzed.Aiming at the inherent problems of slow response and poor robustness of the pump controlled electro-hydraulic servo system,this paper proposes a pump valve parallel system based on the advantages of fast response of the valve control system and high energy efficiency of the pump control system,and studies the high-performance control method of the system.Firstly,a single neuron PID controller is designed for the pump control subsystem in the pump valve parallel system,which can realize the self-adaptive adjustment of the weight.Then,the RBF neural network sliding mode controller is designed for the parameter uncertainty of the valve control subsystem in the pump valve parallel system.Finally,a joint simulation model of MATLAB / Simulink and AMESim is built for the pump valve parallel electro-hydraulic servo system.The simulation results show that the single neuron PID controller of the pump control subsystem has better speed tracking performance than the traditional PID controller,and the RBF neural network sliding mode controller of the valve control subsystem has better position tracking accuracy and stronger anti-interference ability than the traditional PID controller,The designed controller improves the control performance of the pump valve parallel system. |
PDF Full Text Request