Model-based research for aiding decision-making during the design and operation of multi-load automated guided vehicle systems

Multi-load Automated Guided Vehicle's (AGV) are regarded as a potential tool to tackle the low-efficiency issue that have plagued traditional single-load AGV systems for many years. However, to date, the optimal design and operation of multi-load AGV systems is still an unresolved question. In order to explore the answer to this question and help operators make decisions during the design and operation of these systems, this article will use Coloured Petri nets (CPN) to develop a mathematical model to investigate the performance (i.e., the total number of items delivered within a given time) of the multi-load AGV system in various scenarios. The research has shown that the failure of multi-load AGVs can significantly lower the performance of the AGV system. Although it is possible to maintain high system performance by performing onsite corrective maintenance, the research shows that this can be achieved using a combination of periodic maintenance and backup AGV use. Finally, it is found that increasing the number of multi-load AGVs can increase system performance, but will decrease the efficiency (i.e., the average number of items delivered per AGV) of the individual AGVs in the system due to the increased traffic conflicts and hence longer waiting times.