Improved Delay-Dependent Robust Stability Criteria for Time Delay Systems

This paper proposes novel robust stability and robust stabilizability conditions for time delay systems with time-varying delay and nonlinear time-varying perturbations. Using the traditional quadratic approach with Lyapunov-Krasovskii functional in which the Lyapunov-Krasovskii matrices are independent from the time as well as from the nonlinear perturbations, some delay-dependent robust stability and robust stabilizability criteria are derived. The main contribution of this research is to give quadratic-based conditions for stability analysis and controller synthesis of time delay systems without using any bound for cross-terms presented in the time derivative equation. This allows the proposed stability and stabilizability criteria to provide less conservative results than that of reported methods which often employ bounding of the cross-terms. Several examples are considered from the