Nonlinear Adaptive Inverse Control Study Of Direct-Drive Electro-Hydraulic Servo System

Direct-drive electro-hydraulic servo system applies the AC servo motor instead of the servo valve and changes the flow quantity through discharging the pump's rotation speed. It has the advantage of high reliability, simple structure, high effect and capacity of preventing pollution so that it's one of the newest developing direction in hydraulic control research.The paper introduces the latest situation of electro-hydraulic servo system globally on base of lots of references. Build the math model of the system using linear method and status space method. Through analyzing the open-loop characteristic, controllability and observability, we have analyzed the stability. Then finish the simulation of the system without controller.In direct-drive electro-hydraulic servo system ,the nonlinear factors influent the stability and precision of the system. The paper analyze the reason of flow quantity pulsation, dead-zone and disturbution nonlinear and builds the math model. Protecting these nonlinear factors, we choose the control strategy and design the adaptive filter corresponded to the real engineer. The purpose of the adaptive inverse controller is to avoid bad stability caused by feedback. It could deal with the dynamic characteristic and disturbtions separately. Using soft to process the controller could make better response do the system, so it will correct the frailties which are low precision, bad stability and slow response, etc.The paper designs the adaptive inverse controller and classic PID controller with LabVIEW according to the three nonlinear factor. With different loadings, tracking difference signals such as step signal, square signal, Chirp signal, slope signal and sine signal of difference frequency, we compare the responses and get the conclusion. The result of simulation indicate that adaptive inverse control method has solved the problem of bad effect and the unstability caused by the three nonlinear factor.And the method improves the rapidility and the stability of the system. On the other hand, it represents better robust character when the loading is changing.