Sensor Fault Detection in Dynamic Systems Using Robust Observers

Abstract

This paper outlines the theory of a design approach to the detection of faults in dynamic systems using the concept of the robust unknown input observer. The method which is based on eigenstructure assignment makes use of invariance concepts applicable to uncertain systems. The paper provides an interpretation of the process of robust residual generation together with the underlying principles and concepts. The eigenstructure assignment approach makes use of the full design freedom that is available in a multivariable observer system. A careful choice of the observer left eigenvectors enables a high degree of parity space de-coupling to be achieved, giving rise to an efficient fault monitor which is capable of detecting and isolating sensor faults. A discrete time design example is given which is based on a flight control system. Graphical results demonstrate the disturbance de-coupling property of the fault monitor