Abstract
This paper deals with the steady-state performance of lumped LTI feedback systems in the face of plant uncertainty. The plant uncertainty considered here is the multiplicative perturbation at the output port. The necessary and sufficient conditions for various robust steady-state performances are obtained. Internal model principle like results on the structure of controllers achieving various robust steady-state performances are derived from these necessary and sufficient conditions. More importantly, these conditions are transformed into the measure of μ, thus enables the synthesis of controllers achieving robust steady-state performance in the framework of μ synthesis and the generalized H∞ control theory.
