CONVEX-ANALYSIS OF OUTPUT-FEEDBACK CONTROL-PROBLEMS - ROBUST STABILITY AND PERFORMANCE

This paper addresses the problem of optimal H-2 control by output feed back. Necessary and sufficient conditions on the existence of a linear stabilizing output feedback gain are provided in terms of the interse ction of a convex set and a set defined by a nonlinear real valued fun ction. The results can be easily extended to deal with linear uncertai n systems, where uncertainties are supposed to belong to convex bounde d domains providing an H-2-guaranteed cost output feedback control. Th anks to the properties of the above-mentioned function, we show that u nder certain conditions, convex programming tools can be used for nume rical purposes. Examples illustrate the theoretical results.