Contour control of biaxial motion system based on RBF neural network and disturbance observer

Sanxiu Wang,Shengtao Jiang

doi:10.1177/16878140211034842

Abstract

Friction is the main factor which degrades the control precisions of the servo system. In this paper, a cross coupled control method based on RBF neural network and disturbance observer is proposed for multi-axis servo system with LuGre friction, in order to implement high precision tracking and contouring control. Firstly, a feedback linearization controller is designed to realize the position stable tracking for single-axis motion; then, the disturbance observer is used to observe and compensate the friction. However, in practical application, the observation gain is difficult to select, and it is easy to cause observation error. In order to enhance the tracking accuracy and system robustness, the RBF neural network is introduced to approximate the disturbance observation error online. Finally, the cross coupled control is used to coordinate the motion between the axes to improve the contour accuracy. The simulation results show that the proposed method can effectively compensate the influence of friction on the system, has good tracking accuracy and high contour control precision.

Highlights

Multi-axis servo system is widely used in precision machining and other manufacturing fields because of its high speed and high precision.[1,2] The main purpose of multi-axis linkage operation is to realize continuous control of tool or workpiece movement in turn or simultaneously in their respective coordinate system according to the command issued by the control system, so as to process parts with complex contour surface
For two axis permanent magnet linear servo motor contour motion control system, it is easy to be affected by friction disturbance, which reduces the single-axis tracking accuracy, a friction compensation control algorithm is proposed
The control algorithm consists of feedback linearization controller, disturbance observer, and RBF neural network

Summary

Introduction

Multi-axis servo system is widely used in precision machining and other manufacturing fields because of its high speed and high precision.[1,2] The main purpose of multi-axis linkage operation is to realize continuous control of tool or workpiece movement in turn or simultaneously in their respective coordinate system according to the command issued by the control system, so as to process parts with complex contour surface. Keywords Feedback linearization controller, disturbance observer, RBF neural network, cross coupled controller The disturbance observer is introduced to estimate the friction, which is combined with feedback linearization to ensure the single-axis stable tracking.

Results

Conclusion