A Wavelet-based Iterative Learning Control Scheme for Motion Control Systems

Authors:	Chen Jian-Shiang, National Tsing Hua University, Taiwan Tzeng K. S., National United University, Taiwan Tzeng D. C., National Tsing Hua University, Taiwan
Topic:	2.1 Control Design
Session:	Tracking and Disturbance Rejection
Keywords:	Iterative Learning Control, Wavelet Transform, Servo Control

Abstract

A wavelet-based iterative learning control scheme is presented in this article. To improve the learning behaviour, wavelet transform is employed to extract the learnable dynamics from measured output signal before it can be used to update the control profile. The wavelet transform is adopted to decompose the original signal into many low-resolution signals that contain the learnable and unlearnable parts. The desired control profile is then compared with the leanable part of the transformed signal. Thus, the effect from unlearnable dynamics on the controlled system can be attenuated solely by a feedback controller design. Both the feedback and learning controllers are of proportional type to show the efficacy of this proposed scheme. Convergence analysis is also presented to provide theoretical background. A typical DC servo system is employed as the control target for experimental verif