A Deadlock Prevention Approach Using Elementary Siphons of Petri Nets

摘要

This paper deals with the deadlock prevention problem in a new class of nets, ES PR, where deadlocks are related to unmarked siphons. The major disadvantage of the existing approaches is that too many monitors and arcs have to be added. In our deadlock prevention approach, strict minimal siphons are distinguished by elementary and redundant ones. For each elementary siphon, a monitor is added to prevent it from being emptied without generating emptiable control-induced siphons. The controllability of the redundant siphons is ensured by changing the control depth variables of related elementary siphons, which leads to a more permissive and structurally simple liveness-enforcing Petri net supervisor. Finally, an FMS example is applied for illustrating the policy.