Supervisor Design of Unbounded Petri Nets for Discrete Event Systems
针对无界Petri网建模的离散事件系统，提出一种基于整数线性规划的死锁预防方法，通过修改可达树定义两类回路，设计监督控制器确保活性和最大许可性。
A deadlock prevention policy for discrete event systems (DESs) modeled as unbounded Petri nets (UPNs) is developed in this article. A reachability tree, an essential instrument, shows the evolution of UPNs is fundamental for the description and analysis of several characteristics, including liveness and reversibility. Deadlocks are an undesirable situation within the realm of DESs, particularly those represented by Petri nets. This article introduces a method implemented through integer linear programming for UPNs. We explore the modified reachability trees of UPNs from a new lens by defining two classes of circuits, and exploit an algorithm to engineer a supervisor that ensures liveness and maximum permissiveness. The proposed approach can supervise and control all deadlock nodes in a reachability tree such that the closed-loop unbounded net is live. Finally, several typical cases are shown to demonstrate the reported methods.