Set-based Actuator Fault Diagnosis in Lure Systems

In this paper we present a method for actuator fault detection and identification in Lure systems. The Lure plant is controlled by an observer-based feedback tracking controller, designed for the nominal (fault-free) system. A residual signal is constructed from measurable estimation errors associated with the nominal observer. Faults are diagnosed by on-line contrasting the residual signal trajectories against a set of values that the residuals can be shown to attain under healthy or faulty operation. These values are obtained via set-invariance analysis of the system closed-loop trajectories.