Maximum fault-free enforcement in Petri nets using supervisory control

Fault diagnosis and maximum fault-free execution are essential for the development and operation of computer-integrated systems covering aircraft systems, power grid systems, production processes, etc. This paper focuses on the problem of fault diagnosis and maximum fault-free enforcement of systems modeled by labelled Petri nets. Given a system modeled by a labelled Petri net that may enter deadlocks, an extended basis reachability graph that contains sufficient information to characterize deadlocks is used to compress the state space and verify the diagnosability for the considered system. Furthermore, the proposed graph offers sufficient and necessary conditions for fault-free enforcement and deadlock-free enforcement. Finally, a lock-free event set and a supervisor are designed for a system such that any possible fault or dead behaviour is prohibited in the controlled system.