An LMI approach to output-feedback-guaranteed cost control for uncertain time-delay systems

This paper considers the problem of output-feedback-guaranteed cost controller design for uncertain time-delay systems. The uncertainty in the system is assumed to be norm-bounded and time-varying. The time-delay is allowed to enter the state and the measurement equations. A linear quadratic cost function is considered as a performance measure for the closed-loop system. Necessary and sufficient conditions are provided for the construction of a guaranteed cost controller. These conditions are given in terms of the feasibility of LMIs which depend on a positive definite matrix and a scaling variable. A numerical algorithm is developed to search for a full order dynamic output-feedback controller which minimizes the cost bound. Copyright (C) 2000 John Wiley & Sons, Ltd.