Delay-dependent Guaranteed Cost Control of Uncertain Discrete Time-delay Systems

The problem of guaranteed cost control for discrete time-delay systems with norm-bounded uncertainties is considered.An improved delay-dependent condition for the existence of the guaranteed cost controller is developed by introducing a zero formula and slack variable in the forward difference of Lyapunov functional.As the condition is not expressed using strict linear matrix inequlity(LMI) conditions,an iterative algorithm is proposed to solve the non-convex feasibility problem.Two numerical examples show that the proposed method can even give a smaller upper bound for the performance index.