Robust Control for Time-varying Systems

A class of continuous-time systems with periodic coefficients is analysed and controlled by robust linear controllers. Time varying parameters are considered as perturbations of a nominal timeinvariant linear system. The robust control synthesis is based on general solutions of Diophantine equations in the ring of proper and Hurwitz stable rational functions RPS and the Youla-Kučera parameterization of controllers is utilized. Perturbations and robustness of proposed algorithms are studied through the infinity norms (H∞). Resulting control laws for first order systems are of a generalized PI type and a scalar parameter m>0 is introduced for tuning and influencing of control responses. A Matlab + Simulink program system for automatic design and simulation has been developed.