Application Of Disturbance Rejection In Servo Motor Control

Disturbances widely exist in real industrial systems.Therefore,the rejection of disturbances is an unavoidable problem in the design process of control system.For different kinds of disturbances,it is a hotspot problem to design an appropriate control strategy to make the system achieve satisfying performance in the current control community.In this thesis,direct current(DC)servo motor is considered as the research object.In the presence of the disturbance signal,the control algorithm of the motor is designed,and the effectiveness of the disturbance rejection method is verified by theoretical analysis and constructive experimental setup.Firstly,the mathematical model of DC servo motor which is controlled by armature voltage is established and simplified as well.Because of the two unknown parameters in the model,the traditional least squares method is used to identify these unknown parameters.The accurate mathematical model of DC motor is obtained,which lays a foundation for the future research of controller design.Secondly,according to the mathematical model of the servo motor,the effectiveness of the disturbance rejection method is verified by the theoretical analysis.In this thesis,the disturbance observer method is used to estimate the disturbance signal,and backstepping method is adopted to design the appropriate control law.The validity of the method is proved by theoretical analysis.Then,in the presence of two common types of disturbances,the effectiveness of the method is verified by MATLAB numerical simulations.In order to research the application of the disturbance rejection method in the servo motor control,it is necessary to generate appropriate interference signals.In this thesis,a basic experimental setup of signal source is built.This setup mainly uses 51 single-chip to control AD9850 chip,so that it produces a certain frequency signal which can be changed according to user,and the signal information can be displayed on the LCD 1602.The frequency range of the signal source is between 1Hz and 10MHz,which can meet the needs of industrial practice for the basic disturbance signals.Thirdly,a complete experimental setup of DC servo motor system controlled by STM32F103C8T6 chip is also constructed in this thesis.The purpose is to verify disturbance rejection method in experiment.The disturbance generated by the basic signal source is added to the experimental setup of the servo motor.The disturbance observer based control(DOBC)method and backstepping method are used to design an appropriate control law for the servo motor.The experiment results indicate that the disturbance rejection method has a satisfying control effect on servo motor control.Finally,the research is summarized and some open problems of DC servo motor control systems to be explored in the future are pointed out.