Research On Control Strategy Of High Precision Servo System Simulation Platform

The servo system is a motor positioning control system with fast response characteristics.Permanent Magnet Synchronous Motor(PMSM)has the characteristics of simple structure,high reliability and light weight.It is widely used in servo systems in manufacturing,military,aerospace and other fields.Tracking accuracy is the key index to measure its performance.In the design of the servo system,the control method of the system becomes key factors affecting the tracking performance when the parameters of the mechanical equipment such as the drive motor and the reducer are properly selected.Based on the background of the permanent magnet synchronous motor servo system,this paper aims to study the control strategy to improve the tracking performance.In order to solve the problems of slow response,low dynamic performance and poor anti-disturbance capability of the servo system,this paper improves the control strategy from three aspects and form a composite control strategy:(1)Aiming at the slow response of the traditional three-closed-loop control strategy of the servo system,the feedforward correction method is used to improve it and the correction is divided into speed feedforward and acceleration feedforward.This division makes a convenient to determine compensation parameters.(2)The speed loop has the problems of large overshoot,slow stability and poor dynamic performance.The fuzzy control is used to optimize the speed loop controller of the system,which can realize the dynamic adjustment of the controller parameters,reduce the speed overshoot,and further reduce the position tracking error.And the fuzzy control can use the look-up table method,which is easy to realize in the microcontroller.(3)The large tracking error caused by the sudden change of load can be solved by torque observation and compensation.Compared with the sliding mode observer and the Luenberger observer,the disturbance torque observer has the advantages of simple design and less parameters,but it has obvious high frequency errors.Aiming at this problem,this paper adopts a new method,which optimizes the mathematical expression of the disturbance observer by introducing Intermediate variable.It does not need the speed differential as the input of the observer,and eliminates the high-frequency error.Compared with the combination of traditional disturbance torque observer and filter,the improved disturbance torque observer has the advantages of less hysteresis and less computation.According to the actual permanent magnet synchronous motor parameters,a system simulation model is built in MATLAB/Simulink.Simulation experiments have used different conditions to test the performance of the traditional control strategy and the composite control strategy of this paper.The results show that the proposed composite control strategy and the improvement of the disturbance observer are feasible.In the follow-up experiment,the Beckhoff embedded controller CX2040,the Ether CAT AC servo driver and the permanent magnet synchronous motor of Zhuhai Motion Control Motor Company were used to build the simulation platform of the servo system,and the programming of the control strategy was completed on the Twin CAT3 software.Through physical experiments,it proves that the three improvements proposed in this paper can effectively reduce the tracking error of the servo system to less than 1mrad,and the optimization of the disturbance torque observer can reduce the high-frequency error of the observation results.