An approach to enforce disjunction of GMECs on controlled Petri Nets

Abstract

The problem of enforcing disjunction of Generalized Mutual Exclusion Constraints (GMECs) on a Petri Net (PN) system is discussed in this paper. It has been proved that in presence of uncontrollable transitions a GMEC has to be transformed into a proper disjunction of GMECs to be enforced in a maximally permissive way. In addition, some control problems have to be directly specified as a disjunction of GMECs; this is the case when the legal markings belong to a non-convex region. In the literature the problem has been solved by extending the standard enabling rule for PNs by using OR-logic and Inhibitor Arcs. In this paper we propose an algorithm to synthesize a standard PN based controller to enforce a limited non-convex legal marking region under some restrictions.