Error Tracking of Iterative Learning Control Systems

Abstract

This paper presents an iterative learning control method with which the error trajectory can be pre-specified. The method dose not require that the initial condition remains to be a fixed value for each iteration, whereas this requirement is usually assumed in conventional methods. The proposed strategy is to make the tracking error trajectory converge to the pre-specified one over the entire interval. The constant parametrization, time-varying parametrization, and a combined situation are respectively examined. By the Lyapunov-like approach, accordingly, learning laws are given and the learning systems are analyzed in details. With the help of unsaturated/saturated learning law, the system error coincides with the pre-specified error trajectory over the entire interval, and all the signals in close-loop system are guaranteed to be bounded. Numerical results are presented to demonstrate the effectiveness of the proposed learning control method.