 Robot scheduling for pod retrieval in a robotic mobile fulfillment systemAmir Gharehgozli and Nima Zaerpour Transportation Research Part E: Logistics and Transportation Review, 2020, vol. 142, issue C Abstract: In order to increase the order picking efficiency, e-commerce retailers have started to implement order picking systems where mobile robots carry inventory pods to pick stations. In pick stations, pickers pick the products from inventory pods and put them in customer bins. In such a robotic mobile fulfillment center, pickers are constantly busy with picking customer orders and avoid non-value adding activities such as walking to reach storage locations. To fulfill customer orders, each robot needs to complete a sequence of missions and each mission includes a set of retrieval requests. We study the operational problem of scheduling a mobile robot fulfilling a set of customer orders from a pick station. The mobile robot needs to bring each pod from a retrieval location to the pick station and return the pod to a storage location. The objective is to minimize the total travel time of the robot which can be considered as a proxy for other objectives such a shorter lead time, higher throughput and less capital investment. We formulate the basic problem as an asymmetric traveling salesman problem. We then extend the model by adding general precedence constraints to give different priorities to customer orders based on their urgency (e.g. same-day, one-day, two-day, and standard orders). We also study a variation of the problem where the pod can be stored in multiple alternative locations. In this case, we model the problem as a generalized asymmetric traveling salesman problem. An adaptive large neighborhood search heuristic is developed to efficiently solve real size instances. The method outperforms the heuristics commonly used in practice. Keywords: Distribution; e-commerce fulfillment; Robotic mobile fulfillment systems; Travel time; Asymmetric traveling salesman problem (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:eee:transe:v:142:y:2020:i:c:s1366554520307353 Ordering information: This journal article can be ordered from DOI: 10.1016/j.tre.2020.102087 Access Statistics for this article Transportation Research Part E: Logistics and Transportation Review is currently edited by W. Talley More articles in Transportation Research Part E: Logistics and Transportation Review from Elsevier |
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