Nonlinear Adaptive Robust Control Of Hydraulic Servo Joints For Robot

Hydraulic servo joint is the basic component of hydraulic robot,the accuracy of its control performance directly affects the dynamic performance of the robot.In order to improve the control precision and robustness of the electro-hydraulic servo system,reduce the influence of nonlinear and uncertain factors,three controllers based on conventional PID control,fuzzy adaptive PID,feedback linearized sliding mode variable structure control are proposed.Then,the control performance of the controller is compared and analyzed by simulation test,and the best controller is concluded.Firstly,the servo valve,proportional valve and electromagnetic high-speed switching valve which are commonly used in the control system are compared and analyzed.It is concluded that the electromagnetic high-speed switching valve has stronger control performance,response characteristics and anti-pollution ability.Then the electromagnetic high-speed switch valve is used to control the system.Then build a high-speed switch electromagnetic valve simulation model to analyze its performance and verification,the method can be used to improve the response characteristics are obtained.Secondly,the mathematical model of the whole valve-controlled servo joint is established,the flow characteristic equation and torque balance equation are analyzed,define the expected performance index of servo joint system.From this,the theory and control principle of the three kinds of controllers are analyzed,then the controller is designed with the mathematical model of the servo system.Finally,Amesim and Matlab are used to build the simulation model of the system,write the control function,and verify the performance of the controller.Through simulation and comparative analysis,it is concluded that under the ideal state,that is,the system is free from interference,the three controllers can track the target curve rapidly and stably.Among them,the feedback linearized sliding mode variable structure controller has the fastest response speed and the smallest tracking error.Under the condition of time-varying load interference,the response speed of all three controllers decreased slightly.The tracking curves of conventional PID and fuzzy adaptive PID show obvious fluctuations,and the sliding mode variable structure controller runs stably after reaching the sliding mode surface.Then added the interference of hydraulic oil source fluctuation to further test the robustness of the sliding mode variable structure controller.The results show that its tracking state is still stable,which shows that the sliding mode variable structure control system has fast response speed,strong anti-interference ability and excellent robustness,and the sliding mode variable structure control system can achieve the expected goal,even better than the expected goal,and meet the requirements of its application in the field of robot.