A novel nonlinear control scheme-robust iterative learning control (RI
LC) is developed in this paper. The new robust ILC system provides a g
eneral framework targeting at synthesizing learning control and robust
control methods with the help of Lyapunov's direct method, thereafter
being able to handle more general classes of nonlinear uncertain syst
ems. In the proposed control scheme, learning control and variable str
ucture control are made to function in a complementary manner. The non
linear learning control strategy is applied directly to the structured
system uncertainties which can be separated and expressed as products
of unknown state-independent functions and known state-dependent func
tions. For non-structured system uncertainties associated with known b
ounding functions as the only a priori knowledge, variable structure c
ontrol(VSC) strategy is applied to ensure the global asymptotic stabil
ity. In addition, important issues regarding the objective trajectory
categories, resetting condition, derivative signal requirement and the
ir relationships have been made clear in this paper. (C) 1998 Elsevier
Science Ltd. All rights reserved.