Deadlock control of concurrent manufacturing processes sharing finite resources

A novel deadlock control policy is developed for modeling the concurrent execution of manufacturing processes with limited shared resources through a class of nets, ES³PR. A relevant property of the system behavior is that it is deadlock-free. Recent work has shown that deadlock situations in a plant system can be easily characterized by the structural analysis of the system, particularly, in terms of unmarked or insufficiently marked siphons in its Petri net model. The strict minimal siphons in a plant ES³PR net model are divided into elementary and dependent ones. The proposed deadlock prevention policy is to make all siphons satisfy maximal cs-property when the elementary siphons in the plant Petri net model are properly supervised via explicitly adding monitors for them with appropriate initial markings. Compared with the existing approaches in the literature, the advantage of the policy is that a much smaller number of supervisory places (monitors) are added and unnecessary iterative processes are avoided. Finally, its application is illustrated by a flexible manufacturing example.