An efficient deadlock prevention policy based on selective transition covers for flexible manufacturing systems

Behavior permissiveness is one of the most important criterions in evaluating the performance of a Petri net controller. In our previous work, the concept of transition covers is proposed, and based on it, a live Petri net controller with small size is constructed. A transition cover is a subset of maximal perfect resource transition circuits that consist of resource places and transitions and characterize deadlock states of Petri nets. However, there are more than one transition covers for a Petri net, and the performances of Petri net controllers are different based on different transition covers. This paper explores the condition under which the performance of Petri net controllers can be largely improved. Based on the condition, an efficient deadlock prevention policy is established. Finally, two examples are provided to demonstrate the proposed conditions and policy.