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An ordinary Petri‐net (PN) based approach is proposed to design the programmable logical controller (PLC) for preventing collisions between vehicles in an automated guided vehicles (AGV) system. First, method is proposed to model an AGV system as an ordinary PN, called the plant PN. Second, for collision prevention in an AGV system, module control methods are proposed to design the PN supervisor (the closed‐loop PN) by augmenting the plant PN. In detail, three modules are defined the line, divide, and merge modules, in the plant PN, and the control module methods are presented for each of these three modules. As a result, the closed‐loop PN of an AGV system is obtained and can be analyzed using the PN theory. Finally, method is proposed to translate a closed‐loop PN into a ladder diagram. Consequently, the PN supervisor is implemented by a PLC using these proposed methods. A laboratory AGV system is used to illustrate this approach.

An approach is proposed to design the pro grammable logic controller (PLC) for an automated guided vehicle system (AGVS), using ordinary Petri net (PN). First, it models an AGVS as a plant PN. Second, the PN supervisor is designed to firm a closed-loop PN by augmenting the plant PN. Specifically, it adds control transitions to the plant PN to cont . rol the wiring loops that are to make the vehicles stop for loadmg and unloading. The resultant closed-loop PN of an AGVS can be analyzed by PN theories. Lastly, it can translate a closed-loop PN into a ladder diagram that can be performed by a PLC. A laboratory AGVS is used to illustrate the present method.