Unknown input observers for switched nonlinear discrete time descriptor systems

In this paper, a linear matrix inequality technique for the state estimation of discrete-time, nonlinear switched descriptor systems is developed. The considered systems are composed of linear and nonlinear parts. An observer giving a perfect unknown input decoupled state estimation is proposed. Sufficient conditions of global convergence of observers are proposed. Numerical examples are given to illustrate this method. Index Terms--Hybrid systems, polyquadratic stability, switched descriptor systems, unknown input (UI) observers.