Robust nonlinear observer for systems with generalized sector nonlinearity and time-varying delay

A robust nonlinear observer for a class of nonlinear time-delay systems is introduced. The generalized sector constraint is employed to deal with many commonly encountered nonlinearity in dynamic equation. It is assumed that time-varying delay exists in both state and output equations, and further it directly appears in nonlinear function. By utilizing two correction terms in nonlinear observer related to the dynamic equation as well as system's nonlinearity, the stability analysis of observer error dynamic is presented. For uncertain systems, a synthesis method to obtain robust nonlinear observer is then given in terms of some LMI's. The effectiveness of proposed observer and related synthesis method are finally demonstrated through simulation examples.