Research On Performance Comparison And Configuration Optimization Of Three Kinds Of Automated Vehicle Storage/Retrieval Systems

The acceleration of the order response speed of the logistics distribution center puts forward higher requirements on the automated picking system.The Automated Vehicle Storage/Retrieval System(AVS/RS)has the characteristics of strong flexibility and high efficiency,and has been widely used in recent years.According to different mechanical forms,it can be divided into four types—traditional,based on cross shuttles,based on a ring-shaped conveyor and based on four-way shuttles(referred to as traditional system,cross shuttle system,ring-shaped conveyor system and four-way shuttle system),which can realize rapid picking of goods,but only the latter three can realize online consolidation.The premise of this paper is to realize online order consolidation,so only cross shuttle system,ring-shaped conveyor system and four-way shuttle system are studied.Because the three AVS/RS have big differences in system performance and lowest cost,and there are few literatures on the comparative analysis direction,it is difficult for decision makers to choose a better system in the initial stage of logistics distribution construction.To solve such problem,this paper takes the performance difference and optimal configuration of the three systems as the research point to carry out research work.First,analyze the structural layout and operation flow of the three systems.Study the layout and operation process of the traditional system,and analyze the difference in structure and operation process between the three AVS/RS and the traditional system.Then,establish the performance evaluation model of the three systems.Based on the open queuing network model(OQNM),the system throughput and transaction cycle time are solved,and the correctness of the queuing theory model is verified through simulation.On this basis,the performance differences of the three systems under different rack layout inputs are studied.Numerical experiment results demonstrate that the throughput of the four-way shuttle system is the smallest and the transaction cycle time is the longest;when there are more lanes and lower layers,the throughput of the ring-shaped conveyor system is higher than that of the cross shuttle system,but the ring-shaped conveyor system is affected by the ring-shaped conveyor with an upper limit;when the number of lanes is small and the number of layers is large,the throughput of the ring-shaped conveyor system and the cross shuttle system is equal;when the number of lanes and the number of layers are both large at the same time,the throughput of the cross shuttle system is higher,but its transaction cycle time is longer than that of the ring-shaped conveyor system.Finally,the configuration optimization problem of the three systems is studied.This paper designs the lowest cost configuration optimization algorithm for the three systems under the specific warehouse storage size and customer requirements based on the heuristic genetic algorithm,as well as solves the system’s optimal rack layout and equipment configuration and the corresponding minimum system cost.Numerical experimental results show that the costs of the three systems all increase with the increase in throughput under different warehouse scale scenarios of large,medium,and small.When the system throughput is small,the cost of the four-way shuttle system is the lowest;as the throughput increases,the cost advantage of the ring-shaped conveyor system becomes more obvious;when the throughput is higher than the upper limit throughput of the ring-shaped conveyor system,the cross shuttle system needs to be selected.