Further improved results on H∞H∞ filtering for discrete time-delay systems

This paper investigates the H∞H∞ 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∞H∞ performance level. In addition, sufficient conditions for the existence of the H∞H∞ 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.

► This paper investigates the H∞H∞ filtering problem for discrete-time systems. ► Scaled Small Gain Theorem is used to deal with time-delay. ► This leads to less conservative results compared with traditional approaches.