Centralized versus Decentralized Control of Internal Transport, a Case Study
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Since the introduction of wireless truck terminals and the translation of this technology in material handling control systems, a new control area has emerged in the control of such trucks. In this paper special attention is devoted to Fork Lift Trucks (FLTs) with wireless truck terminals which are controlled by a central Warehouse Management System (WMS). In order to justify investments in wireless truck terminals, it is necessary to specify the reduction in the number of vehicles needed and to indicate the impact on response times and throughput times. This is investigated for the case of a distribution center, where a wireless truck terminal system has been introduced. Two situations have been compared via simulation: decentralized conventional control (without mobile terminals) and centralized control with a WMS using so-called work lists. It is shown that, a centralized control system outperforms the conventional control systems. Such a system leads to a 29% reduction of the number of FLTs needed, and a simultaneous reduction in pallet response times. Furthermore, warehouse performance is almost insensitive to the structure of the work lists when centralized control systems with work lists are used.
KeywordsVehicle control forklift truck warehousing work lists
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