Cycle2deadlock control of RGVs in autonomous vehicle storage and retrieval systems

摘要

摘 　 要: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 Pet ri 网和有向图的死锁控制方法。该方法首先应用有色赋时 Pet ri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。Abstract :To avoid the cycle2deadlock of the Rail2Guided Vehicles (RGVs) systems in Autonomous Vehicle Storageand Ret rieval Systems (AVS/ RS) , a deadlock cont rol modeling method based on Pet ri net s and directed graph wasproposed. The dynamic model of AVS/ RS was const ructed by using Colored Timed Pet ri Net s (CTPN) . And by u2sing directed graph tools , the cycle2deadlock was described. To deal with RGVs systems with single rail and two di2rections , forms of cycle2deadlock were also discussed. Moreover , the necessary and sufficient conditions for RGVsdeadlock2 f ree were presented , and the deadlock2 f ree cont rol policies including critical state were also proposed. Fi2nally , a case study was given to validate the effectiveness of the proposed policy.