一种时延Petri网的死锁预防方法

Deadlock prevention approach for a class of timed Petri nets

针对时延Petri网的死锁预防问题,提出了一个有效的预防控制算法,将信标控制死锁预防的方法应用到时延Petri网中,不需要列举全部可达状态的情况下实现死锁预防,而且实现最后的控制器为活.首先将时延Petri网拉伸为拉伸时延Petri网(SPN),使得不改变原来系统性能的情况下,拉伸后的网所有变迁均为单位时延,然后针对SPN忽略时间因素,采用信标控制方法,根据所得标识约束添加控制库所,使所有严格极小信标均为P-不变式可控,最后还原时延Petri网,得到活的、结构简单的Petri网监督控制器.

To solve the problem of deadlock prevention for timed Petri nets, an effective prevention policy based on siphons is proposed. Without enumerating the reachable markings, deadlock prevention is achieved and the final supervisor is live. First, a timed Petri net is stretched into an SPN. Without influence on the system performance, each transition in the SPN has a unit time delay. Then by ignoring the factor of delay time, the siphon-control-based approach is applied. Monitors based on the marking constraints are added to the plant model to ensure all strict minimal siphons in the net invariantcontrolled. A liveness-enforcing supervisor with a simple structure can be realized by reverting the TPN.