A divide-and-conquer method for the synthesis of non-blocking supervisors for flexible manufacturing systems

This paper proposes a divide-and-conquer method to synthesize non-blocking supervisors for a class of generalized Petri nets, namely G-system. A novel deadlock prevention method is presented by utilizing the reachability graph (RG). Due to the RG of a large Petri net model (PNM) easily becomes unmanageable, an optimal non-blocking supervisor based on RG becomes a challenging problem in a generalized Petri net. To facilitate this problem, the PNM of a large scale system is divided into small connected subnets. Each connected subnet prone to deadlocks is then used to compute the liveness-enforcing supervisor for the original PNM. The proposed method in general provides an optimal or a near-optimal solution of the non-blocking supervisor. Finally, a G-system example is used to illustrate the applicability and the effectiveness of the proposed method.