Abstract: The scattered storage characteristics of the mobile-rack storage system have brought new challenges to the allocation of commodity storage locations. To handle the problem, it is necessary to consider both the correlation of commodities and the quantitative relationship among commodities. By considering the dual relationships of commodity type and quantity, the storage allocation problem under the mobile-rack-based picking mode is studied, and an integer programming model is established to minimize the total number of rack movements in order picking. In view of the NP-Hard characteristic of the model, a variable neighborhood-tabu search algorithm is designed according to the characteristics of the problem. Through the operation of changing the neighborhood, the number of sub-bins covered by an item is changed, and the degree of dispersion of the commodity is indirectly affected. The order picking results may be influenced by the operation of the tabu search algorithm on the quantities of items of a rack. In addition, the breadth and depth optimization capabilities of the algorithm are further improved by the downsizing strategy.

Key words: mobile racks; storage location allocation; commodity type-quantity dual association; variable neighborhood-tabu search