Design of Robust Modified Repetitive-Control System for Linear Periodic Plants

This paper concerns a linear-matrix-inequality (LMI)-based method of designing a robust modified repetitive-control system (MRCS) for a class of strictly proper plants with periodic uncertainties. It exploits the nature of control and learning and the periodicity and continuity of repetitive control to convert the design problem into a robust stabilization problem for a continuous-discrete 2D system. The LMI technique and Lyapunov stability theory are used to derive an LMI-based asymptotic stability condition that can be used directly in the design of the gains of the repetitive controller. Two tuning parameters in the condition enable preferential adjustment of control and learning. A numerical example illustrates the tuning procedure and demonstrates the effectiveness of the method.