Stability Analysis And Robust Control Of Nonlinear Systems With Time Delay

It's well known that time delay,nonlinear perturbations,uncertainties,widely existing in the practical systems,are often the main causes of bad performance or even in stability for control systems.Delay-dependent stability results have less conservativeness than the delay-independent ones,since the former can provide the size of delay such that the system keeps stable.Therefore,many researchers have paid much attention and made some efforts on it.In this paper,by using the Lyapunov stability theory,matrix inequality tactics,matrix decomposition technique,and the method for dealing with nonlinear term,the problems of robust stability and the design of robust controller for several types of nonlinear system have been investigated based on LMI.The main contents of this paper are outlined as follows:1.The new robust stability conditions for a class of time delay system with nonlinear perturbations are proposed through introducing new augmented Lyapunov functional and employing the Free-Weighting-matrix(FWM) method.2.Firstly,we deals with the absolute stability of Lur'e control systems with timevarying delay by using the normal and augmented Lyapunov functional,and employing the FMW method.Then,the obtained results are extended to the robust stability for uncertain systems with norm-bounded or polytopic-type uncertainties.Furthermore,a sufficient stabilization criterion is established for the close-loop system in the terms of linear matrix inequality(LMI),based on the stability condition and matrix decomposition technique.3.For a class of neutral system with both state and input delays,a delay-dependent sufficient condition of robust stability is addressed.Also,by introducing some tuning parameters,the state feedback controller is derived.