Abstract
This paper investigates the H-infinity filtering problem for a class of discrete-time systems with time-varying delay. A model transformation is first applied by employing a two-term approximation for delayed state variables, which has a smaller approximation error than the other one-term approach. By using Scaled Small Gain Theorem and Lyapunov-Krasovskii functional approach, sufficient conditions are provided for the stability of the filtering error system with a prescribed H-infinity performance level. In addition, sufficient conditions for the existence of the H-infinity filters are established which are less conservative than the existing results in the literature. Finally, numerical examples are provided to illustrate effectiveness of the proposed filtering scheme. (C) 2013 Elsevier B.V. All rights reserved.