Deadlock prediction and avoidance based on Petri nets for zone-control automated guided vehicle systems |
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Authors: | C-C LEE J T LIN |
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Affiliation: | Department of Industrial Engineering , National Tsing Hua University , Hsinchu, Taiwan, 30043, Republic of China |
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Abstract: | Deadlock problems of zone-control uni-directional automated guided vehicle (AGV) systems are discussed in this paper. Deadlocks of two types in such AGV systems are first classified from the perspective of shared resources, i.e. guide-path zones and buffers. A special class of Petri nets, attributed Petri nets (APN), is defined and used to represent the current state and to generate future states of zone-control AGV systems. We propose an algorithmic procedure to predict in real time and to avoid deadlocks that are caused by sharing guide-path zones in zone-control AGV systems. The proposed algorithm utilizes the current system state and future predicted states to avoid deadlocks. These states are obtained and generated from the obtained APN. A modular approach is employed to facilitate the construction of APN models of zone-control AGV systems. |
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