Deadlock problems of zone-control uni-directional automated guided vehicle systems (AGVS) are discussed in this paper. A directed graph is defined to model the vehicle flows, to identify distinct vehicle flows, to represent stages easily and to capture concurrent behaviour of zone-control AGVS. The motiva- tion of this research was to propose a dynamic approach to enable prediction in real time and to avoid deadlocks that are caused by sharing guidepath zones for a class of AGVS so that both utilization of resource and overall throughput can be improved. The proposed algorthmic procedure, in accordance with the states gained and generated from the obtained model, can serve as a functional module for he operation of a zone-control AGVS without the need to revise the original vehicle control extensively.
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