Less conservative H∞ filter design for systems with time-varying interval delay

H_infin filter design for systems with time-varying interval delay is investigated in this paper. Improved delay dependent H_infin performance condition is presented by using the free-weighting matrix approach and considering the relationship among the time-varying delay, its upper bound and their difference. As a result, a modified cone complementary linearisation (CCL) algorithm with a new stopping condition is employed to derive the filter gain. Finally, a numerical example is given to demonstrate the effectiveness and the benefits of the proposed method.