Study On The Control Of Nonlinear Servo Systems With Unknown Dynamic

In recent years,permanent magnet synchronous motors have gradually become one of the most promising motors in the industrial field due to their simple structure,high efficiency,and energy saving.They are widely used in railway traction systems,electric vehicles,aerospace and other fields.However,the uncertainty and external interference in the motor will affect the speed accuracy of the motor,and how to overcome the uncertainty and external interference in the system has important research value and significance for the speed tracking accuracy of the motor.Aiming at the motor system with uncertainty and external disturbance,this paper designs a method to solve the external disturbance problem and improve the response speed based on sliding mode control,adaptive control,uncertain disturbance estimator,nonlinear observer and other methods.The main research contents are as follows :(1)Considering the uncertainties and unknown disturbances of permanent magnet synchronous motor servo system,a sliding mode controller based on uncertain estimator is designed.Firstly,the uncertain disturbance estimator is designed to estimate the unknown disturbance.Then,aiming at the problems of chattering and poor tracking accuracy of the motor,a sliding mode control strategy of permanent magnet synchronous motor based on uncertain disturbance estimator is designed,and the stability of the system is proved based on Lyapunov theory.Finally,the simulation is carried out under different external interference conditions.The simulation results show that the tracking error of the designed controller is close to 0,which proves that it has good anti-interference ability.(2)In order to reduce the dependence on model data information,an adaptive sliding mode control method based on robust integration of error symbols is designed.Firstly,the robust integral observer of the error sign is designed and its stability is proved.Then,an adaptive sliding mode controller is designed and the stability of the system is proved based on Lyapunov theory.Finally,the simulation and experiment are carried out under different external conditions.The simulation and experimental results show that the method improves the response speed by 0.1 s and reduces the overshoot.(3)In order to simplify the process of calculation and parameter adjustment,a fast terminal sliding mode control of permanent magnet synchronous motor based on nonlinear observer is designed.Firstly,the nonlinear observer is improved to estimate the external disturbance.Then,the new hybrid reaching law is improved,and the fast terminal sliding mode controller is designed based on it.The stability of the system is proved based on Lyapunov theory.Finally,simulation and experiment are carried out under different external conditions.The simulation and experimental results show that the method can effectively improve the uncertainty and external interference.The method improves the response speed by 0.05 s and improves the chattering of the sliding mode controller.