Decentralized supervision of Petri nets with a coordinator

This paper develops a decentralized supervision policy for a Petri net through collaboration between a coordinator and subnet controllers. The coordinator is chosen from the subnet controllers by solving an integer linear programming problem. An optimal objective function is used to minimize the communication cost between the subnet controllers and the coordinator. Furthermore, a protocol to reach an agreement on the firing conditions of common transitions among the subnet controllers is proposed. Observation agreement and control agreement can be achieved by the “AND” operator in logic algebra. Control agreement is used to decide the firing conditions of common transitions in the next step. The firing of common transitions, which will lead to a new marking that violates the given constraints, will be forbidden by the control agreement. A feasibility analysis of the proposed decentralized control framework is discussed. Finally, four examples are presented to illustrate the proposed approach.