Research On Adaptive Control Of Hydraulic Servo System

The rapid development of science and technology has led to the widespread use of hydraulic servo systems in all manner of control systems.Such control systems generally have the performance requirements of high accuracy and fast response.Hydraulic servo system is a type of high-order nonlinear control system with time varying parameters,which has severe parameter uncertainty and uncertain nonlinear features so that it is difficult to obtain the precise mathematical model of the system.So that the hydraulic servo system has improved trajectory tracking accuracy and robustness,in this thesis,the hydraulic servo system for injection molding machine was taken as the object of research,this thesis proposed three controllers based on conventional PID control,backstepping control,and adaptive control,and established the Amesim and C language co-simulation platform as well as the semi-physics simulation platform.The control performance of the three designed controllers was verified through simulation under the same task environment and system parameters.The simulation results were then compared and analyzed,and the controller with the best control performance is finally determined.Firstly,the working principle of the servo hydraulic valve actuated actuator system power mechanism was analyzed.Since the effective piston area in the two asymmetric cylinder cavities is different,there is no consistency in the dynamic characteristics of the hydraulic actuator moving in different directions,which causes the system to easily cause a large hydraulic pressure jump and vibration of the system during the inversion process,which has severe detrimental effects on the dynamic performance of the system.Therefore,different mathematical models were established for valve controlled symmetric cylinder and valve controlled asymmetric cylinder system.Secondly,by introducing and analyzing the theory and principle of control algorithms,the design of PID,backstepping and adaptive controller was completed.The adaptive control algorithm realized the combination of the control flow and the adaptive law based on the backstepping method,in order for the system to have good control and estimation leverage at the same time.Then,the two simulation methods used in this thesis were introduced.The co-simulation environment of Amesim and C language was introduced,the construction method of co-simulation was described in detail,and the correctness and practicality of the co-simulation platform was tested with an example.In order to further verify the accuracy of the controller and increase the fidelity of the simulation experiments,the goal of the semi-physics simulation platform was to make the simulation results more similar to the real system.This thesis lays the groundwork for the simulation experiment that follows.Finally,according to the algorithm structure of PID,backstepping,and adaptive control,different simulation models of the hydraulic servo system were established in the co-simulation and semi-physics simulation platform,and the three control algorithms were programmed by the C language.By comparing and analyzing the simulation results,it is concluded that the most suitable control strategy for valve controlled cylinder systems is adaptive control.