Research On Several Problems Of Multi-tier Shuttle-based Storage And Retrieval System

Recently,the commercial order structure has gradually changed from "large quantity,small batch" to "small quantity,large batch".Therefore,traditional manual labor cannot cope with this labor-intensive industry.However,this issue can be settled by multi-tier shuttle system because of its high efficiency and thus it is becoming a hot topic in warehouse management and industry application area.Multi-tier shuttle-based storage and retrieval system is more complicate and has unique superiority in modern logistics system because of which dual-command multi-tier shuttle system is attracting more and more attention.This paper focuses on the optimization of storage rack and equipment's speed in dual-command multi-tier shuttle system,which have great theoretical and practical significance.Firstly,the system composition is briefly discussed.Then,the inside operation procedure,in-bounding procedure,out-bounding procedure and system operation time of multi-tier shuttle system under single-command and dual-command are discussed separately.It lays a foundation for the optimization of storage contracture and equipment speed in the following chapters.Secondly,an optimal storage rack model is established with the objection of shortest operation time.A modified Nelder-mead algorithm is proposed to calculate the shortest operation time under different scenarios,like racks with different ratio of length to height or length to depth.Finally,the simulation results prove that the models of dual-instruction multi-tier shuttle system are accurate and can provide designers with reasonable guidance.Last but not least,the energy consumption is taken into consideration.An energy consumption model is established based on the analysis of the consumed energy during horizontal and vertical operation of shuttle and vertical operation of lift as well as the total energy consumption of the whole system.Base on this model,a multi-objection optimization model is proposed which expects to obtain the superior results of storage rack contracture,operation time and equipment speed at the same time.According to the simulation experiments,this multi-objection optimization model can successfully find the balanced point of these three objections.