Composite Dispatching Rules for Multiple-Vehicle AGV Systems

The objective of this research is to evaluate the performance of three composite AGV dispatching rules which can be easily implemented in manufacturing or assembly systems. Attempts were also made to compare the composite rules to a simple dispatching rule and to identify system operating parameters which might affect the performance difference of the rules. Composite dispatching rules tested in this study are based on combinations of concepts proposed in previous research. Discrete event simulation models were developed to implement the heuristic rules in a hypothetical assembly system with a zone control scheme to avoid vehicle collision. The simulation result revealed that a combination of the Nearest Station and the Stay-in-the-same-station (NS-SS) rule outperformed the other rules. Statistical analyses on the simulation output suggest that a composite rule which minimizes the AGV travel distance might be a good control strategy, and the operational factors which affect the performance difference are dependent on the type of dispatching rules.