Design And Implementation Of Location Allocation And Storage/Retrieval Operation Generation For Gravity AS/RS With Duration-of-stay Storage Strategy

Warehousing is an indispensable part of modern logistics,the scheduling center and inventory control center of modern logistics and supply chain.It plays an important role in the whole supply chain.In order to cope with the increasing demand of logistics,the shortage of land resources and the rising cost of human resources,warehouse managers hope to increase the utilization rate of warehouse storage space with the combination of information,automation and intelligent warehouse management without increasing the floor area of the warehouse.The gravity automated storage and retrieval systems(The gravity AS/RSs)is an automated storage and systems(AS/RS)with high storage density,high floor space utilization,low investment cost and low operating cost.Items are stored to the storage end of a bin,slide to the retrieval end driven by the gravity and retrieved from the retrieval end.The performance of the gravity AS/RSs heavily affect by the distribution of items to storage locations and the sequence of storage and retrieval operations.Therefore,it is necessary to design reasonable and effective distribution method of items to storage locations and the generation method of storage and retrieval operations to improve the performance of the gravity AS/RS.The research has practical significance and theoretical value,and the main contributions of this paper are as follow:(1)Optimize distribution of items to storage locations.In the duration-of-stay(DOS)storage policy,according to the arrival time and departure time information of all items,a hybrid grouping-matching heuristic is proposed.In the whole planning horizon,minimize the total travel time of storage and retrieval operations by assigning more items to bins which are closer to the pick-up/drop-off stations.(2)Optimize the sequence of storage and retrieval operations.Based on the distributions of items to storage locations,a Hungarian-heuristic method is proposed to generate reasonable the sequence of storage and retrieval operations.As many as possible dual-command(DC)operations are generated in the single bin to minimize the total time of storage and retrieval operations.(3)Based on the research of the above two points,a warehouse management system for small and medium-sized enterprises is designed and implemented.The warehouse management system has the functions of optimizing items to storage locations and optimizing the sequence of storage and retrieval operations.