Improved Delay-dependent Stability Criteria for Systems with Nonlinear Perturbations *

This paper studies the delay-dependent robust stability for time-delay systems with nonlinear perturbations. A new method is proposed to estimate the upper bound of the derivative of Lyapunov functional without ignoring some useful terms. Improved delay-dependent stability criteria are established by taking into account the range for the time-delay. In addition, augmented Lyapunov functionals are introduced to derive less conservative delay-dependent stability conditions. Finally, numerical examples are given to demonstrate the effectiveness and the merits of the proposed method.