A Deadlock Prevention Policy for a Class of Petri Nets S3PMR

This paper focuses on the problem of deadlocks in automated flexible manufacturing systems (FMS) where deadlocks are caused by unmarked siphons in their Petri net models. A deadlock prevention policy is proposed for a subclass of Petri nets, SPMR that can well model a large class of FMS. We distinguish siphons in such a net model by elementary and dependent ones. For each elementary siphon, a monitor is added to the plant model such that it is invariant-controlled. The monitor addition way guarantees that no emptiable control-induced siphon is generated due to the presence of monitors in the resultant net. This novel deadlock prevention policy can usually lead to a more permissive supervisor by adding a small number of monitors and arcs than the existing methods for the design of liveness-enforcing Petri net supervisors. Experimental study indicates that the proposed policy appears to be more permissive than closely related approaches in the literature.