Delay-dependent robust H∞ control of nonlinear systems based on observer

Based on observer, delay-dependent robust H_∞ controller design problem for time-delay systems with a class of nonlinear uncertainties is discussed in the paper. Assuming that the nonlinear uncertain functions in the considered model are gain-bounded, we obtain a sufficient condition for the robustly asymptotic stability and H_∞ performance of the closed-loop system in the light of Lyapunov stability theory. By solving a pair of linear matrix inequalities (LMIs), we construct delay-dependent dynamic output feedback control law which guarantees the robustly asymptotic stability of the closed-loop system and reduce the effect of the disturbance input on the controlled output to a prescribed level. The delay-bound or the H_∞ performance bound can be optimized. A numerical example illustrates the potentiality of our claim.