The Design Of Speed Control For DC Servo Motor Based On Dynamic Disturbance Compensation

DC servo motor has been widely used in industrial robots,Numerical control machine and many other control systems because of the advantages of low energy-consumpt,easiness in control and fast response.At the same time,there are uncertainties and disturbances in the motor,which have a negative impact on its performance.How to reduce the influence of external load disturbance and parameter variation is of great significance to the high-speed dynamic response and high-accuracy tracking performance of DC servo motor.In this paper,an active disturbance rejection method based on extended state observer is introduced,and active disturbance compensation and robust repetitive control is proposed to improve the robustness of the system and achieve high precision tracking of the reference input signal.The research work mainly includes the following three aspects:(1)Speed Control of DC Motor Servo System Based on Linear Active Disturbance Rejection MethodA speed control method based on linear active disturbance rejection control is proposed for DC motor servo system with parameter uncertainty and external load disturbance.Firstly,the uncertainties and external loads are considered as the lumped disturbance of the system,and the integral-chain state space model is established by the transfer function.The extended state observer is constructed by introducing a new state variable(lumped disturbance)to estimate the states and lumped disturbance of the system in real time,and a disturbance compensator is constructed to jointly establish the structure of the servo augmented system.On this basis,the sufficient conditions for the stability of the closed-loop system are obtained by applying the small gain theorem.Then,the bandwidth parameter optimization technique is used to separate the extended state observer from the state feedback controller.Finally,it shows that the designed DC motor servo system has satisfactory disturbance rejection performance by comparing the simulation results of this method with traditional PID control.(2)The Robust Design of DC Motor Servo System Based on modified Extended State ObserverFor DC motor servo system with mismatched disturbances,a disturbance estimation and compensation method based on modified extended state observer is proposed to eliminate the influence of uncertainties and external load disturbances on system output.Firstly,all uncertainties and external load disturbances in the general state space model are summed up as lumped disturbance,which are regarded as new state variables,and the linearized augmented state space model of the original system is obtained.Then,a modified extended state observer is constructed to estimate the system states and lumped disturbance,and the lumped disturbance estimation is fed back to the input of the system by using the variable gain disturbance compensation.A composite control law is designed to realize real-time compensation of the lumped disturbance and stabilization control of the system.The stabilityconditions of the system and the design steps of the controller are given in this paper.Finally,the simulation results are compared with the standard extended state observer based control method,which shows the superiority of the proposed disturbance estimation and active compensation method.This method is suitable for general state space model of DC motor,and doesn't strictly require integral-chain model.At the same time,it can effectively suppress the influence of mismatched disturbance on the output of the system,thus extending the application of linear active disturbance rejection control.(3)The Design of Robust repetitive control for DC servo motor system based on disturbance compensationFor DC motor servo system with periodic reference input and external load disturbance,a repetitive control method based on modified extended state observer is proposed to improve the disturbance rejection performance and tracking performance at the same time.The system can be viewed as a conventional repetitive control system combined with a modified extended state observer and a disturbance compensator.This means that the design procedure of the system can be divided into two stages.Firstly,the modified extended state observer is constructed to estimate the system states and lumped disturbance,and the disturbance estimation is fed back to the output channel of system to eliminate real lumped disturbance through the variable gain disturbance compensator,so as to improve the anti-jamming ability of the system.Then,repetitive controller compensator and feedback controller are designed to stabilize the conventional repetitive control system and improve the periodic tracking performance without aperiodic disturbance.Here,the stability criterion and a two-stage design procedure of the system are developed.Finally,simulation results have illustrated the validity of the method.It has been shown that the proposed modified extended state observer based repetitive control for DC motor servo system has better both disturbance-rejection performance and tracking performance than conventional PID control,PID based repetitive control,modified extended state observer based PID and standard extended state observer based repetitive control does.