Robotized Warehouses: Design and Performance Analysis



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Warehouse automation requires considerable scale and a long-term vision, as the investments can be earned back only in the medium and longer-term. Furthermore, there is no one-size-fits-all solution for warehouse automation and depending on the type of the warehouse and its position within the supply chain, different automation should be considered. The majority of warehouse research still focuses on conventional storage and order picking methods. Due to rapid system developments, it is time for an update, as the new technologies have provided new and interesting research opportunities. Therefore, in Chapter 2, we structure the latest automated technologies and overview these technologies and the research. We also review the modeling techniques used and the research opportunities they provide. Chapter 3 investigates the vertical storage and retrieval system, an emerging robotic technology for e-commerce warehouses. We build a framework to analyze and optimize the performance of the system. We also compare the effects of different robot blocking protocols on the system throughput. Finally, we compare the operational costs of the vertical and conventional horizontal systems. The results show that the vertical system produces a similar or higher system throughput with a lower operating cost compared with the horizontal system in almost all scenarios. In Chapter 4, we study systems in which robots collaborate with a human picker to efficiently pick the orders by reducing the pickers’ unproductive walking time. Particularly we investigate how higher pick performance can be achieved by dynamically switching between different pick strategies. The results show that a dynamic switching policy can lower operational costs by up to 7 percent. However, these cost savings decrease as the number of robots per picker increases.