Feedback-Assisted High-order Iterative Learning Control of Uncertain Nonlinear Discrete-time Systems

A high-order iterative learning controller (ILC), assisted by a feedback controller, is proposed for the tracking control of uncertain discrete-time nonlinear systems which perform a given task repeatedly. The uniform bounded-ness of the tracking error is obtained in the presence of bounded uncertainty, disturbance and the re-initialization error even without the assistance of the feedback controller. The control input saturation has been considered. It is also shown that under certain conditions, the tracking error bound is a function of the bounds of the diierences of uncertainties, disturbances and the re-initialization errors between two successive ILC iterations. Simulation illustrations are given.