Robust H∞ control for parameter uncertain system with time-varying delayed states: output feedback case

This paper deals with the problem of designing a robust H^∞ controller for parameter uncertain system with time-varying delay. The control problem with both parameter uncertainties and unstructured uncertainties is reduced to one with unstructured uncertainties only under preserving quadratic stability and H^∞ norm bound. In the transformed system, we can solve the problem using elementary manipulations on linear matrix inequalities (LMIs) considering time delay term. Also, sufficient conditions for the existence of robust H^∞ output feedback controller of any order are presented in terms of three LMIs