Robust H∞ filter design for a class of uncertain systems with time-varying state-delays

In this paper, using Lyapunov-Krasovskii (LK) functional approach, we consider the problem of delay-dependent H_∞ filter design for a class of uncertain linear systems with interval time-varying delays. The uncertain system under consideration is subjected to an unknown exogenous disturbance signal. In the proposed design approach, by exploiting an appropriate LK functional, and using minimal number of slack matrix variables, a less conservative sufficient condition for the existence of a robust H_∞ filter is derived in linear matrix inequality (LMI) framework. The proposed H_∞ filter guarantees that the estimation error is asymptotic even if the measurement signals are corrupted by noise; in addition, for a prescribed specification on the time-varying delay, the proposed filtering technique achieves a minimum noise attenuation level than the existing result that is recently reported. The effectiveness of the proposed result is illustrated using a numerical example.