Fault Isolation Module Implementation using a Timed Discrete-Event Approach based on Interval Observers

Abstract

This paper proposes a fault diagnosis method using a timed discrete-event approach based on interval observers which improves the integration of fault detection and isolation modules. The interface between fault detection and fault isolation considers the degree of fault signal activation and the occurrence time instants of the fault signals using a combination of several theoretical fault signature matrices which store the knowledge of the relationship between fault signals and faults. As a novelty, this paper illustrates the procedure to implement the fault isolation module using a timed discrete-event approach built on the grounds of an interval observer used to model the monitored system. In this way, the diagnosis result will be enhanced since the occurrence of a fault generates a unique sequence of observable events (fault signals) that will be recognized by the isolation module implemented as a timed discrete-event system. The states and transitions that characterize such a system can be inferred directly from the relation between fault signals and faults. The proposed fault diagnosis approach is applied to detect and isolate faults of the Barcelona's urban sewer system limnimeters (level meter sensors).