Two-dimensional robust modified repetitive control for uncertain systems with disturbances

This study concerns the problem of disturbance rejection in a modified repetitive control system for a linear uncertain plant. First, we present the configuration of the modified repetitive control system. It has a new structure of the modified repetitive controller so as to improve the feasibility of the control system, and incorporates an equivalent input disturbance estimator in it to improve the disturbance rejection performance. Then, a sufficient condition of the robust stability is derived in terms of a linear matrix inequality using the two-dimensional system theorem and the Lyapunov stability theory. Finally, a numerical example demonstrates the validity and superiority of the method.