Robust h∞ dynamic output feedback control for linear time-varying uncertain systems via switching-type controllers

The problem of designing robust H _∞ switching-type controllers via dynamic output feedback for uncertain linear systems is studied. The uncertainties are assumed to be time varying, unknown, but bounded, which appear affinely in the matrices of system model. Here, a switching mechanism is introduced to construct a novel robust H _∞ controller with time-varying gains and to reduce the conservativeness inherent in traditional robust H _∞ controllers with fixed gains. The proposed controller gains are switching between a number of fixed gains automatically, which depend on the bounds of uncertain parameters. New sufficient conditions with less conservativeness than those for designing traditional robust controllers with fixed gains are also derived to guarantee the stability and H _∞ performances of the closed-loop systems, and a two-step linear matrix inequality (LMI)-based procedure is proposed for designing switching controllers. A numerical example is given to illustrate the effectiveness of the proposed method.