Reduced-order observer design for a class of generalized Lipschitz nonlinear systems with time-varying delay

This paper investigates the H_∞ reduced-order observer design problem for a class of nonlinear systems with interval time-varying delay which satisfies the quadratically inner-bounded condition and encompasses the family of Lipschitz systems. A novel reduced-order observer design methodology for nonlinear systems is proposed. By utilizing a newly extended reciprocal convexity inequality, free-weighting matrix technique, and quadratically inner-bounded condition, the less conservative existence conditions of the proposed nonlinear H_∞ observer are derived. The new sufficient conditions in terms of linear matrix inequalities (LMIs) guarantee asymptotic stability of the estimation error dynamics with a prescribed performance γ. Two numerical examples are given to illustrate the effectiveness of the proposed approach.