Robust Iterative Learning Control Design Based on Gradient Method

An iterative learning control (ILC) method using both feedback and feedforward actions is proposed for a class of uncertain linear systems to achieve precise tracking control. A sufficient condition for the plant uncertainty and feedback controller, which guarantees the robust convergence of the learning, is given. The procedure of designing the robust algorithm has two steps: At first, the feedback controller with robust performance is synthesized based on H∞ optimal approach according to the request of the sufficient condition; secondly, the incremental feedforward input signal is derived by gradient method with fixed step size. It is shown that the feedforward action has relation to the adjoint system of the closed nominal system. Copyright © 2003 IFAC