Adaptive Model-Free Coupling Controller Design for Multi-Axis Motion Systems

Bo-Sheng Chen,Ching-Hung Lee

doi:10.3390/app10103592

Abstract

In this study, we introduce an adaptive model-free coupling controller while using recurrent fuzzy neural network (RFNN) for multi-axis system to minimize the contour error. The proposed method can be applied to linear or nonlinear multi-axis motion control systems following desired paths. By the concept of cross-coupling control (CCC), multi-axis system is transferred into a nonlinear time-varying system due to the time-dependent coordinate transformation; tangential, normal, and bi-normal components of desired contour. Herein, we propose a model-free adaptive coupling controller design approach for multi-axis linear motor system with uncertainty and nonlinear phenomena. RFNN establishes the corresponding adaptive coupling controller to treat the uncertain system with nonlinear phenomenon. The stability of closed-loop system is guaranteed by the Lyapunov method and the adaptation of RFNN is also obtained. Simulation results are introduced in order to illustrate the effectiveness.

Highlights

In industrial applications, multi-axis motion systems have been applied many machining systems, e.g., machine tools, position stage of semi-conductor equipment, and robot manipulators
We introduce an adaptive model-free coupling controller while using recurrent fuzzy neural network (RFNN) for multi-axis system with uncertainties to minimize the contour error
An illustrated example for the estimation of contour error is introduced and the discussion of adaptation of controller is presented to demonstrate the performance of adaptive coupling control

Summary

Introduction

Multi-axis motion systems have been applied many machining systems, e.g., machine tools, position stage of semi-conductor equipment, and robot manipulators. The contour error is usually adopted to evaluate the control performance; it is defined as the error component orthogonal to the desired path. For practical mechanical control systems, the contour error always exists due to mechanical structure, servo lag, as shown in Figure 1 [1,2,3], ec : contour error, ewy : tracking error in y axis, and ewx : tracking error in x axis. The trend of smart manufacturing is high speed and accuracy; the minimization of contour error is more important. Most of industrial controllers used are PID controllers and multi-axis synchronization is less common. The multi-axis control approach as proposed to treat it [4,5,6,7,8,9,10,11,12,13,14]

Objectives

Methods

Results

Discussion

Conclusion