This paper defines clearly and presents the fundamental properties of automated guided vehicle systems (AGVS) and their relationship to Petri nets. The objective is to develop an intelligent modelling tool to allow the design of robust AGVS models using some invariant Petri-net properties. The Petri-net properties of the system are presented in terms of safeness, boundedness, strict conservation, reachability and liveness. The robustness of the system at floor-level is embedded into the model by introducing system traffic collision-free, constant numbers of vehicles and traffic control signals, path reachability, and system traffic deadlock-free. Two different merge structures are presented to illustrate the effectiveness of the present approach. The result shows the strength of Petri-net theory in the modelling of complex AGVS. The AGVS models thus built are robust.
