Deadlock control policy using control transitions for flexible manufacturing systems

Unlike the deadlock prevention policies by adding control places (CPs) in most existing literature, this paper proposes a concept of control transition equation (CTE) and the corresponding deadlock control policy (DCP) by adding control transitions (CTs). By analyzing the reachability graph (RG) of an original net (N0;M0) with deadlocks, all deadlock markings (DMs) are found by this DCP. The desired CTs are constructed on the basis of the proposed CTE. Accordingly, the corresponding CT is added to each DM in order to make all DMs in the original net (N0;M0) eliminated. So a live controlled system (N*;M*) is obtained. The correctness and efficiency of the proposed DCP is verified via the theoretical analysis and the relevant examples in the existing literature. Moreover, the reachable number of the live controlled system (N*;M*) obtained by the proposed DCP is the same as that of the original net (N0;M0), i. e., maximally reachable number (MRN). © 2019, Editorial Department of Control Theory & Applications South China University of Technology. All right reserved.