Research On The Storage Assignment Problem In Robotic Mobile Fulfilment System

Storage assignment is an important part of ensuring the efficiency of the warehouse operation.In the robotic mobile fulfillment system,the results of storage assignment decide the pod selection of order production and thus affect the picking efficiency.Different from storage assignment problem in the traditional warehouse,the problem of storage assignment in robotic mobile fulfillment system is an one-to-many decision,that is,an item is stored in many storage bins to ensure the dispersion of distribution of items and the flexibility of the warehouse system.After the item's storage is determined,as the order increases,the items on the pods changed,in order to ensure the dispersion of the distribution of items,it need to adjust the layout of the pods.Based on the actual situation of the robotic mobile fulfillment system,this paper studies the problem of storage assignment and pod layout,including the following aspects:First of all,I collect relevant information,introduce the robotic mobile fulfillment system operation process,storage assignment problem,genetic algorithm,and then studied the storage assignment problem of the general robotic mobile fulfillment system and the storage assignment problem of robotic mobile fulfillment system using synchronized zoning.The mathematical model of each problem is established and the corresponding algorithm is designed.For the storage assignment problem of the general robotic mobile fulfillment system,based on the degree of relevance between commodities,the data mining method is used to extract the commodity relevance matrix,and the integer programming with the maximum total relevance of the items on the same pod is established.A hybrid algorithm for solving the storage assignment problem is designed.First,the greedy algorithm is used to determine the initial solution of the storage assignment,and then the improved single-parent genetic algorithm is used to optimize the initial solution.By comparing with the exact optimal solution obtained by CPLEX for integer programming,the validity of the proposed model and algorithm is verified.It is also proved that the proposed algorithm can solve the large-scale storage allocation problem that CPLEX cannot solve.For the problem of the storage assignment problem of robotic mobile fulfillment system using synchronized zoning,based on the solution results of the general robotic mobile fulfillment system,the storage assignment problem is transformed into the pod layout optimization problem,and the correlation degree between the pods is considered.An integer programming model with the minimum total distance of the moving pods is designed,and a hybrid algorithm for solving the model is designed.First,a clustering method is used to cluster the pods,and then the greedy algorithm designed in this paper is used to distribute the pods.The simulation experiment is carried out in the real warehouse.The results show that the total distance of the robot movement is reduced when complete the same batch of orders,which verifies the effectiveness of the proposed model and algorithm.