Nonconservative LMI criteria for delay-independent stability of delay systems, based on quadratic Lyapunov-Krasovskii functionals

Studies the delay-independent stability of delay systems of retarded or neutral type. It is shown that the strong delay-independent stability is equivalent to the feasibility of a certain linear matrix inequality (LMI), viz. to the existence of a certain quadratic Lyapunov-Krasovskii functional, independent of the (non-negative) value of the delay. This constitutes the analogue of some well-known properties of finite-dimensional systems. This result gives a method for the computation of some non-trivial structured singular values. It is applied to studying the delay-independent stability of systems with polytopic uncertainties