A Method for Reducing Tracking Error of Machine Tool Servo Feed System

Abstract

The invention discloses a method for reducing tracking error of a machine tool servo feeding system. The method comprises following steps: 1) modeling for the machine tool servo feeding system and obtaining a system model for the servo feeding system; 2) establishing a frictional force mathematical model for the machine tool servo feeding system and identifying parameters; 3) performing pre-estimation to position variation of the servo feeding system by use of a Kalman state observer, calculating compensation frictional force for the servo feeding system according to the pre-estimated position variation, and performing real-time dynamic compensation to the servo feeding system frictional force according to the calculated compensation frictional force. According to the invention, Kalman state observer is used for realizing frictional force pre-estimation, and system tracking error is accurately controlled through frictional force compensation so that the frictional force real-time variation can be observed and pre-estimated in real time by the system and the frictional force can be compensated in the control system. The method can greatly reduces servo system tracking error.

Description

technical field [0001] The invention belongs to the technical field of numerical control machining, and more specifically relates to a method for reducing the tracking error of a servo feed system of a machine tool. Background technique [0002] Servo feed systems are widely used in digitally controlled mechanical manufacturing and processing. There are many nonlinear characteristics in the system, such as friction, gap, hysteresis effect and external disturbance, these nonlinear characteristics will have a great impact on the performance of the system, among which the influence of nonlinear friction on the motion control performance of the system most notably. For the high-precision table servo feed system, after eliminating the pitch error and clearance of the ball screw, the friction in the feed system becomes the main reason affecting the motion control accuracy. How to effectively eliminate the influence of friction becomes the key to precise control question. [000...

AI Technical Summary

Problems solved by technology

[0003] For how to realize the control of the following error of the servo feed system through the control and compensation of friction force, some studies have been given in the prior art. The existing schemes based on the friction compensation of the classical model have certain effects, but the classical model is a static model. It cannot show the dynamic characteristics of friction force very well, and these dynamic characteristics will seriously affect the system performance, especially the tracking performance and positioning accuracy

Therefore, in the motion control that requires high positioning accuracy, it is difficult to meet the performance requirements by using the friction static model for compensation, and directly using friction feed-forward compensation, or directly introducing friction as a disturbance into the control system, cannot real-time Observing the change of the friction force, it is impossible to adjust the compensation parameters in real time to compensate the friction force, so the accuracy of the compensation effect is not high

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