A livelock control policy for a flexible manufacturing system modeling with a subclass of generalized Petri nets

摘要

Livelocks, like deadlocks, can result in the serious problems in running process of flexible manufacturing systems (FMSs) as well. Current deadlock control policies based on the approaches of siphon detection and control, cannot cope with livelocks in a system of sequential systems with shared resources (S~(4)R), a typical subclass of Petri nets that can model FMSs. On the basis of the mixed integer programming method, this study proposes a livelock control policy (LCP) that can not only solve the new smart siphons (NSSs) associated with livelocks or deadlocks in an S~(4)R system directly, but also make the solved NSSs max′-controlled by adding the corresponding control places (CPs). As a result, an original S~(4)R system with livelocks or deadlocks can be turned into the live controlled one in which no NSSs can be found. The related theoretical analysis and several examples are given to demonstrate the proposed LCP. Compared with the existing methods in the literature, the proposed one is more general and powerful.