Research On Optimization Of Retrieval Operation On Double-deep Multi-tier Shuttle System

With the rapid development of e-commerce and the change of consumer consumption pattern,the demand for the order picking operation of the e-commerce logistics center is becoming higher and higher,and the order picking operation has also become the pain spot of the e-commerce logistics center.In recent years,the double-deep multi-tier shuttle system has become the best way for the order picking operation in ' goods arrive' system with its flexible operation and high efficiency.It has been widely used in the fields of e-commerce,medicine and electric power.The double-deep multi-tier shuttle system relies on the shuttle and the lift to complete the retrieval task together.Because the system uses double-deep rack,it is possible to do the rearrangement operation in the retrieval operation.Based on large number of the domestic and overseas references,it is found that the theoretical research on the double-deep multi-tier shuttle system is still at the starting stage,and the related research about the rearrangement operation is very few.Based on the operation mode of parallel retrieval of shuttle and progressive transfer of the lift in the system,the time model of the retrieval operation considering the rearrangement operation is established,and this paper analyzed and researched from the two aspects of the reverse rearrangement operation strategy and the task scheduling.The main contents and achievements of this paper are as follows:1.Travel time model of retrieval operation considering the rearrangement operation is developed.The double-deep multi-tier shuttle system has the fact of parallel retrieval of shuttle and progressive transfer of the lift,and the r rearrangement operation may occur in the retrieval operation.Based on the above analysis,this paper developed travel time model of retrieval operation considering the rearrangement operation and qualitatively analyzed the influence factors of the efficiency of the retrieval operation,and emphatically analyzed how to optimize the rearrangement operation by shortening the rearrangement distance and reducing the number of rearrangement operation to improve the system efficiency of the retrieval operation.2.A rearrangement partition policy is proposed.Based on the rearrangement operation of the system,a new kind of rearrangement partition policy is proposed.Each tier of each rack is divided into several partitions according to the same rows.A rearrangement position is set in each partition for rearrangement operation,and the rearrangement position is constantly updated during the retrieval operation of the system.Based on the above analysis,this paper established the time model of the rearrangement position under the rearrangement partition policy.Through the simulation technology,the changing trend of the retrieval time with the partition number x is obtained,and the simulation results are analyzed.The study provides the theoretical support and data reference for the actual rearrangement operation of the system.3.The task scheduling problem is optimized based on the rearrangement partition policy.Inspired by the production scheduling problem,a task scheduling optimization model is established based on the objective function of the shortest time of a retrieval operation.The task scheduling problem in this paper mainly focuses on the s the task sequence.The reasonable task sequence can reduce the waiting time of the lift on the one hand,on the other hand,it can also reduce the number of rearrangement operation of the system,and then achieve the purpose of improving the overall efficiency of the system.In this paper,the improved simulated annealing algorithm is applied to solve the above problems,and the effectiveness of the model and algorithm is verified by the case analysis.