Fault Detection for Linear Systems by Multiple Observers and Ellipsoidal Analysis

A new actuator fault detection approach is proposed in this paper for linear systems subject to unknown disturbance and noise. By considering that only one actuator in the system occurs fault at a time, limited number of fault modes are obtained. For each fault mode, an observer is synthesized to generate the residual signal. Especially, the observer is optimized for certain mode to improve the system's sensitivity to faults. Based on the determined multiple observers, a residual evaluation and fault detection decision scheme are presented by the ellipsoidal analysis techniques. Numerical simulation of a VTOL aircraft system is utilized to demonstrate the validity of the presented scheme.