Research On Operation Planning Problem In Multi-shuttle AS/RS Considering Emergency Order Insertion

Based on the common order uncertainty environment of e-commerce warehouses,this paper investigates the countermeasures for multi-shuttle AS/RS operation planning in the case of emergency pick-up order insertion.We establishes the linear programming model and stochastic model respectively-from the two perspectives of emergency insertion and active improvement of normal operation planning margin.The emergency order insertion model to minimize the system fluctuation by adjusting the operation plan when the new instruction comes.That means the execution order of the normal pickup instruction is affected as slightly as possible,and the total delay cost is minimized.Then neighborhood search(NS)algorithm is developed to solve this problem.The small-scale instances result shows that the NS algorithm is feasible and effective.By comparing with two simple strategies,it is proved that the strategy of the emergency insertion model can effectively reduce the total delay cost while reducing system fluctuations.On the basis of the emergency order insertion model,the active reservation model considers the situation that the new picking instruction has a high frequency,and actively reserves the vacancy in the normal operation planning,which can reduce the impact of the new instruction insertion on the overall planning.Because the new instruction appears as a random factor,the sim-heuristics algorithm containing both deterministic and simulation models is developed to evaluate the quality of the solution through multiple numerical experiments.From the experimental result,it is found that the active reservation model performances better when the new instruction frequency is higher and the new instruction delay cost is lower.The normal planning time in active reservation model is generally greater than that in emergency insertion model,while the target value is less.The solution's quality of active reservation model is higher in most cases.The higher the frequency of new instructions,the more obvious the advantages.However,it is noted that the normal completion time of normal instructions in the two models is different,so the decision makers need to weigh the risks and benefits according to the specific situation to decide which model to apply.The contributions of this paper are: 1)firstly consider the problem of multi-shuttle AS/RS picking operation planning adjustment under the condition of emergency plug-in for the first time;2)establish the mathematical models from two perspectives respectively;3)develop comprehensive algorithm including deterministic model and simulation model for random factor.And it's proved that the model solution can effectively reduce the system fluctuation caused by random factor through the numerical experiments.Through the sensitivity analysis of the frequency of new instructions and the delay of new instructions,the impact of parameters on the model results is deeply demonstrated,which provides a basis for managers' decision-making.