Further result on robust H∞ control of uncertain discrete-time systems with time-varying delay

In this paper, the robust H_infin control problem is considered for a class of uncertain discrete-time systems with time-varying state delay. Based on the Lyapunov functional method, and by reserving the useful term when estimating the upper bound of the difference of Lyapunov functional, the new sufficient condition for the existence of the H_infin controller is obtained in terms of linear matrix inequality (LMI). Numerical example is presented to show the effectiveness and less conservativeness of the proposed method.