DESIGN AND OPERATIONAL ISSUES IN AGV-SERVED MANUFACTURING SYSTEMS

Automated Guided Vehicle (AGV) systems are already in widespread use a nd their importance for material handling is expected to grow rapidly. The advantages that such systems can offer include increased flexibil ity, better space utilization, improved factory floor safety, reductio n in overall operating cost, and easier interface with other automated systems. This survey focuses on design and operational issues that ar ise in AGV systems. The objectives of the paper are to unify various l ines of research related to AGVs and to suggest directions for future study. We consider problems arising in flowpath design, fleet sizing, job and vehicle scheduling, dispatching and conflict-free routing. Flo wpath design problems address computationally intractable issues in th e physical layout of a single loop and complex networks. Transportatio n and related models, waiting line analysis and simulation approaches are used to address fleet sizing questions. Scheduling issues focus on three flowpath layouts. In line layouts, the most important issues in clude finding an efficient job sequencing algorithm and identifying op timal AGV launch times. In loop layouts, issues such as joint scheduli ng of the job and AGV schedules, interface with a larger manufacturing system, dynamic job arrivals, and the location of the AGV parking are a, are important. For complex network layouts, joint scheduling, heuri stic dispatching rules, and conflict-free routing of AGVs, are conside red. We identify the inefficiencies that result from addressing these issues in isolation, suggesting the need for integration. We also prov ide a summary of the most important open research issues related to al l the above topics.