Improved delay-dependent robust H∞ filtering of continuous-time polytopic linear systems with time-varying delay

This paper revisits the problem of delay-dependent robust H∞ filtering design for a class of continuous-time polytopic linear systems with a time-varying state delay. Based on a delay and parameter-dependent Lyapunov-Krasovskii functional combined with Projection Lemma, a new sufficient condition for robust H∞ performance analysis is firstly derived and then the filter synthesis is developed by using a novel matrix linearization technique. It is shown that the desired filters can be constructed by solving a set of linear matrix inequalities. Finally, a numerical example is given to show the effectiveness and less conservatism of the proposed method in comparison with the existing approaches. © 2008 IEEE.