一种改进型的S4PR网活性条件

研究了顺序资源共享分配系统的建模模型S4PR (Systems of sequential systems with shared resources)网的活性问题. 已有的研究成果表明, 一个S4PR网在所有信标都满足max, max'或max"-controlled 时能保持活性, 但现有的活性条件对信标的限制严格且不适用于某些网系统, 本文提出了一类名为max*-controlled的改进型条件, 并证明了当一个S4PR网的所有信标都满足max*-controlled条件时, 网系统能保持活性. 与现有的其他条件相比, 新的活性条件更加宽松, 为设计更高允许度的死锁预防或者活性保持监控器提供了理论支撑.

An Improved Liveness Condition for S4PR Nets

This paper studies the liveness problem for S⁴PR (systems of sequential systems with shared resources) nets, a class of Petri net models of flexible manufacturing systems. Current research indicates that an S⁴PR net is live if all its siphons are max, max', or max"-controlled. However, these conditions tend to be overly restrictive and are not available to some net systems. This paper presents an improved condition called max^*-controlled condition and proves that an S⁴PR net is live if all its siphons are max^*-controlled. Compared with the preceding ones, this new condition is more general and can be a theoretical support for designing deadlock prevention or liveness-enforcing supervisor which is more permissive on system behavior.