Robust H∞ filtering for uncertain discrete-time systerms with time-varying delay

This paper focuses on robust H_∞ filter design for discrete-time systems with time-varying delay. Base on Lyapunov method, and a new technique to deal with the upper bound of some terms in the Lyapunov functions, a new less conservative H_∞ performance analysis result is obtained. Moreover, the result deduces a new sufficient condition for systems with polytopic-type uncertainties. Based on the result above, the H_∞ filter is designed in terms of linear matrix inequalities (LMIS). Finally, numerical examples are presented to show less conservativeness of the proposed method.