Free-weighting matrices approach to H∞ filtering for a class of uncertain linear systems with time-varying delay

This paper investigates the problem of delay-dependent robust H_infin filtering for uncertain linear systems with time-varying delay. Given a stable system with parameter uncertainties residing in a polytope with s vertices, the focus is on designing a robust H_infin filter such that the filtering error system is robustly asymptotically stable with a prescribed H_infin noise attenuation level. The main technique used is the free-weighting matrix method by considering the additional useful terms. As a result, an improved linear matrix inequality-based delay-dependent stability criterion is obtained, which is less conservative. Finally, two examples have been presented to illustrate the effectiveness of the proposed methodology.