Proposal of a modeling methodology for factory automation systems and the improved Petri net controller

In this paper, we propose a modeling methodology for factory automation (FA) system and the improved Petri net controller. In the methodology, the whole state of FA system is described by Petri nets. The Petri nets become very large. Thus the methodology requires high-speed Petri net controller. We proposed the Petri net controller previously (1991), but it has two problems: 1) fireable transitions are not always fired, 2) transitions connected to permissive places are not fired preferentially. In the improved Petri net controller, 1) the token state is held for ensuring fireable transitions are always fired, 2) firing priority levels are fixed to all transitions. Its processing speed is faster than before. Assuming Petri nets consist of 512 places and 512 transitions, the Petri net controller takes about 530 kbit memories and 9,000 gates, and it can be on one chip