Study On Elaborate Friction Modeling And Error Compensation For Servo Feed System Based On GMS Model

With the development of precision machining technology,the demand for high-grade CNC machine tools in China is increasing,and the performance requirements for its positioning accuracy are increasingly strict.In order to reduce the impact of nonlinear friction,friction compensation technology has become the main technology to improve the positioning performance of machine tools.At present,the lumped component friction model is widely used in friction compensation method,which does not take into account the difference between the friction model of ball screw and linear guide.The effect of friction compensation is seriously affected.Therefore,it is necessary to establish the model of the different components in the ball screw feed drive system separately and establish the elaborate friction model of the system.The aim of this paper is to improve the tracking performance of feed drive system and reduce the nonlinear friction disturbance.A series of researches have been carried out on friction modeling,identification and compensation.The main contents are as follows.(1)A new type of ball screw feed drive system is designed according to the research content of the subject.The mechanical transmission structure,measurement system,drive system and control system of the feed drive system are analyzed and components are selected.In addition,the installation method of the force sensor and torque sensor in the measurement system is designed to meet the needs of the identification of the friction parameters of the distributed components model.(2)This paper starts from the analysis of the friction mechanism between the ball screw and the linear guide,and the differences in friction characteristics of each component are taken into account.The friction parameters of the ball screw and the linear guide are identified separately,and the elaborate friction model of the feed system based on GMS model is established.Then,according to the identified friction parameters,the corresponding simulation model is established to simulate the friction characteristics of the system.(3)According to the characteristics of feed drive system,the corresponding friction compensation strategy is proposed.Based on the P-PI cascade controller,the feedforward term based on the distributed component model is added.Considering the influence of external disturbance on the performance of control system,a comprehensive friction compensation strategy including disturbance observer and friction feedforward compensation is proposed,and the simulation is carried out in Matlab/Simulink.(4)Based on TwinCAT platform,an open CNC system of the new feed drive device is built.The accuracy of the proposed friction model is verified by experiments,and then the performance of the corresponding comprehensive friction compensation method is verified...