A robust iterative learning controller design for uncertain nonlinear systems

This paper presents the design of a robust iterative learning controller for a class of nonlinear systems with non-parametric uncertainties. The unknown nonlinearities are only required to satisfy the local Lipschitz condition. The learning controller is developed, by using both robust control and iterative learning control methods, which enables to compensate for the shortcoming when either one is applied separately. The closed-loop stability and learning convergence are established in this paper. It is shown that the robust part can guarantee that all the variables in the closed-loop are bounded, and the learning control part can effectively eliminate the tracking error. An inverted pendulum system is taken as an example, and the computer simulation is carried out in order to demonstrate the effectiveness of the proposed learning scheme.