A robust approach to iterative learning control design for uncertain systems

This note proposes a frequency-domain design method to achieve an iterative learning controller for uncertain feedback control systems. For a linear time-invariant plant with multiplicative perturbations and a feedback controller, we derive a sufficient condition for the iterative process to converge for all admissible plant uncertainties. Based on the derived sufficient condition, we show that the iterative learning control design problem can be reformulated as a general robust control problem setup. Consequently, the iterative learning controller under plant uncertainty can be systematically designed by well-established robust control design procedures. (C) 1998 Elsevier Science Ltd. All rights reserved.