H∞ output feedback control for uncertain systems with time-varying delays

In this paper a new approach is proposed to design an H_∞ output feedback controller for uncertain systems with time-varying delay. By defining a new relaxed Lyapunov parameter matrix and introducing some free-weighting matrices, convex linear matrix inequality (LMI) based sufficient conditions are established to ensure robust and exponential stability and to meet a prescribed H_∞ performance level for the resulting closed-loop system. The advantages of the proposed approach are that the Lyapunov parameter matrix is relaxed and the conservatism of results is reduced largely. Moreover, due to the convex LMI form, it can be directly tested and solved the controller parameters by LMI toolbox in Matlab and iterative algorithm is not required. Two examples are given to show the effectiveness and the less conservatism of the results.