应用控制变迁的柔性制造系统死锁控制策略

Deadlock control policy using control transitions for flexible manufacturing systems

中文关键词  柔性制造系统  Petri网  死锁控制策略  控制变迁  最大可达数

英文关键词  Flexible manufacturing system (FMS)  Petri net  deadlock control policy (DCP)  control transition (CT)  maximally reachable number (MRN)

中文摘要

      不同于目前许多文献中基于添加控制库所的死锁预防策略, 本文提出了控制变迁方程(control transition equation, CTE)的概念和相应的基于添加控制变迁(control transition, CT)的死锁控制策略(deadlock control policy,DCP). 通过分析存在死锁的原网(N0, M0)的可达图(reachability graph, RG), 该DCP求解出所有死锁标识(deadlock marking, DM). 基于CTE, 构造出所需的控制变迁. 然后, 对每个DM添加相应的CT, 进而消除了原网(N0, M0)中的死锁标识, 得到了活性受控网系统(N*,M*). 通过理论分析和相关算例的应用, 该DCP的正确性和有效性得到了验证. 此外, 该DCP获取的(N*,M*)可达数目与(N0,M0)是相同的, 即最大可达数(maximally reachable number, MRN).

英文摘要

      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 (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. Moreover, the reachable number of (N*,M*) obtained by the proposed DCP is the same as that of (N0,M0), i. e., maximally reachable number (MRN).