A Robust Fault Estimation Scheme for a Class of Nonlinear Systems

Abstract

This paper presents an observer-based robust fault estimation scheme for a class of nonlinear systems. We consider the system where the fault enters both the state and output equations via unmeasurable nonlinear functions, for which currently no fault estimation scheme exists. The proposed scheme exploits the special structures and information embedded in the fault-dependent nonlinear functions. We propose a design method to minimize the ℒ2 gain from the disturbances to the fault estimation, and provide conditions for the existence of such observers. The effectiveness of this scheme is demonstrated on a nonlinear single-link flexible joint robot system with disturbances.