Petri net modeling and deadlock analysis of parallel manufacturing processes with shared-resources

Multiple resource-sharing is a common situation in parallel and complex manufacturing processes and may lead to deadlock states. To alleviate this issue, this paper presents the method of modeling parallel processing flows, sharing limited number of resources, in flexible manufacturing systems (FMSs). A new class of Petri net called parallel process net with resources (PPNRs) is introduced for modeling such FMSs. PPNRs have the capacity to model the more complex resource-sharing among parallel manufacturing processes. Furthermore, this paper presents the simple diagnostic and remedial procedures for deadlocks in PPNRs. The proposed technique for deadlock detection and recovery is based on transition vectors which have the power of determining the structural aspects as well as the process flow condition in PPNRs. Moreover, the proposed technique for dealing with deadlocks is not a siphon-based thus the large-scale PPNRs for real-life FMSs can be tackled. Finally, the proposed method of modeling and deadlock analysis in the FMS having parallel processing is demonstrated by a practical example.