Resource-Oriented Petri Net for Deadlock Resolution in Automated Manufacturing Systems with Robots

An automated manufacturing system (AMS) contains a number of versatile machines (or workstations), buffers, and an automated material handling system (MHS). The MHS can be an automated guide vehicle system, and/or a system that consists of multiple robots. The issue of deadlock resolution in AMS is very important in the operation of AMS and extensively studied. Usually, robots are seen as source of deadlock when used as MHS in AMS. However, in this paper, such AMS called robotic manufacturing systems (RMS) are modeled by resource-oriented Petri nets. It is shown that the robots have no contribution to deadlock. More interestingly, they can be used to resolve deadlock by serving as temporary part storage devices. A new deadlock control policy for RMS is proposed by treating robots as both material handling devices and buffers. The new policy is shown more permissive than the existing ones.