Monitoring system for discrete event systems using failure-tolerance techniques

Depending to the danger process, it is possible to express a marking zone influenced by the risk phenomenon (influencing zone). Our proposition consists of imposing, using a controlled object Petri net, a firing sequence named safe sequence in the influencing zone. These compensatory actions are established by the object Petri net structure. They are defined as procedures linked with transition actions and executed during their firing. These kind of procedures determine the value of the control vector. The control-monitoring system proposed is composed of a control module and a monitoring module. As for the control module, we find the plant controlled by the control vector. The monitoring module is composed of a marking comparator for detection and diagnosis, and a compensator which calculates the control vector under failure