Design of Supervisor Ensuring Deadlock Free for

Abstract—An effective deadlock prevention policy is proposed to solve the deadlock problem for a class of Petri nets, which is SPR nets. Firstly, the method of LIP is used to find the minimal siphons which may lead to deadlocks. Secondly, for every minimal siphon, a monitor is added to it by the approach of P–invariant which then ensures that none of them would be emptied without generating new control-induced minimal siphons. Thanks to this policy, complete siphon enumeration is avoided without generating new minimal siphons that will be emptied. Therefore, it has greatly decreased the computational complexity, avoided repeated iterations and simplified the supervisors. An FMS example is used to illustrate the proposed deadlock prevention policy. Index Terms—Petri net, siphon, FMS, deadlock prevention I