Diagnosis of transient faults in quantised systems

Abstract This paper concerns the diagnosis and identification of faults that occur in systems where signals can only be measured through a quantiser. A qualitative model is used that represents the discrete-event behaviour of the quantised system. Three different diagnostic algorithms are presented for determining the fault probabilities, the first concerning faults currently affecting the system and the second determining the probabilities that faults occurred at any time in the past. The third algorithm is based on the assumption that the faults occurred only during a time interval in the past. Due to this assumption, the algorithm is applicable for continuously running processes and for the online identification of transient faults. The approach is illustrated by an example of a manufacturing cell.