Stability analysis and H∞ filtering for delay differential systems of neutral type

Stability analysis and H(infinity) filter design for linear neutral systems is discussed. First, a new Lyapunov-Krasovskii functional is constructed to derive a new less conservative delay-dependent stability condition. It is then shown that the introduction of more free matrices sometimes cannot help reduce the conservatism of the obtained conditions. This new criterion is applied to designing a suitable H(infinity) filter of the Luenberger observer type, and a new design scheme is formulated in terms of the feasibility of a linear matrix inequality. Finally, some examples are given to illustrate the effectiveness of the proposed approach.