Process failures diagnosis in FMS real-time control: an approach combining rule-based systems and Petri nets

Focusses on the diagnosis function of a real-time control and monitoring system fitting the specificities of flexible manufacturing systems (FMS). The most important problem in such a diagnosis system, is the need of real-time informations about the process state. Moreover, as in FMS the manufactured products often change, the monitoring system cannot easily adapt the role of a task. In the proposed approach, the knowledge embedded in Petri net models used for control purposes allow one to bypass these difficulties: the Petri net marking is a reflect of the actual state of the process, and the sequences of activities are dynamically used to build a failure propagation tree