A simulation study on the performance of load-selection rules for multiple-load AGVs

This paper studies the load-selection problem defined in the multiple-load AGV control methodology proposed by Ho and Liu (2004). Their control methodology divides the control problem of multiple-load AGVs into four sub-problems: Task-determination problem, delivery-dispatching problem, pickup-dispatching problem, and load-selection problem. A load-selection problem occurs when a vehicle (with a pickup task) arrives at the output queue of a machine. In this problem, one determines which load a vehicle should pick up from the output queue of a machine. Various load-selection rules are proposed. The objective of this study is twofold. We want to understand not only the performance of load-selection rules, but also the effects that pickup-dispatching rules have on load-selection rules' performance. Simulation experiments were conducted to achieve these objectives. Finally, it is our hope that the knowledge learned from this study can assist engineers in having better control of their AGVs in a real system similar to the one studied here.