Abstract

Pick up‐dispatching problem together with delivery‐dispatching problem of a multiple‐load automated guided vehicle (AGV) system have been studied. By mixing different pick up‐dispatching rules, several control strategies (alternatives) have been generated and the best control strategy has been determined considering some important criteria such as System Throughput (ST), Mean Flow Time of Parts (MFTP), Mean Tardiness of Parts (MFTP), AGV Idle Time (AGVIT), AGV Travel Full (AGVTF), AGV Travel Empty (AGVTE), AGV Load Time (AGVLT), AGV Unload Time (AGVUT), Mean Queue Length (MQL) and Mean Queue Waiting (MQW). For ranking the control strategies, a new framework based on MADM methods including fuzzy MADM and TOPSIS method were developed. Then several simulation experiments which had been based on a flow path layout to find the results were conducted. Finally, by using TOPSIS method, the control strategies were ranked. Furthermore, a similar approach was used for determining the optimal fleet size. The main contribution of this paper is developing a new approach combining the top managers′ views in selecting the best control strategy for AGV systems while trying to optimize the fleet size at the mean time by combining MADM, MCDM and simulation methods.

Highlights

  • In modern manufacturing systems, automated guided vehicles (AGVs) have become an integral part of material handling system (MHS)

  • Material handling systems have been playing an important role in an flexible manufacturing system (FMS) as pointed out by Tompkins and White [2] such that about 13%–30% of total production costs can be attributed to material handling operations and it is why many researchers have been looking for the new approaches to optimize the MHS since 1980s

  • The greatest weights belong to System Throughput (ST) and Mean Queue Waiting (MQW) and the lowest one belongs to AGVI criterion

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Summary

Introduction

In modern manufacturing systems, automated guided vehicles (AGVs) have become an integral part of material handling system (MHS). An AGV is a driverless, batterypowered vehicle (usually controlled by on-board computers), and a transport system used for horizontal movements They were introduced in 1955 [1] for the first time and since several applications of AGVs have been developed day by day. In these systems, a number of AGVs—which are always called as fleet size—are dedicated to some workstations and storehouses in order to transport the materials. In designing an AGV system, many tactical (e.g., system design like P/D points, the fleet size, flow path layout, etc.) and operational (e.g., routing or dispatching strategies) problems have been addressed. In designing of an AGV system, at least the following tactical and operational issues have been considered in the literature:

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