自动小车存取系统中轨道导引小车环路死锁控制的研究

Cycle-deadlock control of RGVs in autonomous vehicle storage and retrieval systems

为防止自动小车存取系统中轨道导引小车环路死锁现象,提出了一种基于Petri网和有向图的死锁控制方法。该方法首先应用有色赋时Petri网建立了自动小车存取系统的动态模型,并结合有向图工具,阐述了导致环路死锁的原因。在此基础上,针对单一轨道双向运行的轨道导引系统,探讨了其环路死锁的主要表现形式,给出了轨道导引小车无死锁运行的充要条件,并提出了包含临界状态在内的死锁避免控制策略。最后,结合实例说明了环路死锁控制的有效性。

To avoid the cycle-deadlock of the Rail-Guided Vehicles （RGVs） systems in Autonomous Vehicle Storage and Retrieval Systems （AVS/RS）, a deadlock control modeling method based on Petri nets and directed graph was proposed. The dynamic model of AVS/RS was constructed by using Colored Timed Petri Nets （CTPN）. And by u- sing directed graph tools, the cycle-deadlock was described. To deal with RGVs systems with single rail and two directions, forms of cycle-deadlock were also discussed. Moreover, the necessary and sufficient conditions for RGVs deadlock-free were presented, and the deadlock-free control policies including critical state were also proposed. Finally, a case study was given to validate the effectiveness of the proposed policy.