Stability in the presence of persistent plant changes for a compact set of plant models

In this paper we consider the use of periodic controllers for simultaneous stabilization and performance, with a focus on the case when there is an occasional, though persistent, plant change. We consider the case of a compact set of admissible models; we provide a design procedure which yields a controller which stabilizes each such model and provides near optimal LQR performance. We also demonstrate that this control law has the facility to tolerate occasional (but persistent) switches between these models. The controller is periodic with a slight nonlinearity.