Sensor Redundancy for Robustness in Nonlinear State Estimation

A sensor fault-tolerant estimation methodology for a class of nonlinear systems is addressed in this paper. The main idea of existing sensor fault-tolerant observers in the literature is the detection and reconfiguration of observers by using available healthy sensors. However, based on that idea, a transient time is required for the observers to return to a normal state which may not be practical in many missions. The main contribution of the current study is to develop an estimation strategy such that the effect of faults in sensors is rejected without any abnormal transient behavior under some conditions based on the availability of healthy sensors. By developing a robust nonlinear observer exploiting the measurement of a sufficient set of redundant sensors, it is feasible to reject bounded faults in the sensors such that a desired performance for state estimation is achieved. Simulation results verify the accuracy of the proposed estimation methodology.