Local state observers for nonlinear systems

This paper propose a robust nonlinear unknown input observer “this an extension of the Luenberger observer in unknown inputs” based on first order Taylor expansion. The observer is characterized by its simplicity in the mathematical development can also attack a large class of nonlinear systems without go through a canonical transformation. A systematic method for calculating the gain of the observer is presented [11]. The necessary and sufficient conditions for the existence of the observer are given. A numerical example is given to illustrate the attractiveness and the simplicity of the new design procedure.