Travel Time Models For Elevating Shuttle-based Storage And Retrieval System Under Single And Dual Command Cycle

The development of modern logistics has gradually weakened the most primitive warehousing functions of traditional warehouses,and the requirements for reliable and efficient dismantling and picking operations have gradually increased.The high demand for high-level and highly automated storage and retrieval equipment has become an inevitable trend.Among them,the design and application of shuttle-based storage and retrieval system(SBS/RS),an automated warehouse equipped with a shuttle on each floor,has attracted more and more attention.Aiming at the current optimizable direction of SBS/RS,an elevating shuttle storage and retrieval system(E-SBS/RS)that can carry out low-elevation and vertical movement on the same floor serving multi-levels has been proposed.While the system is stable,it can effectively improve the utilization rate of the shuttle and reduce the investment cost.However,there has been no research on the physical design and control strategy of E-SBS/RS,so this paper refers to the relevant literature of SBS/RS,analyzes the composition and operation characteristics of E-SBS/RS,and carries out the following research under the random storage.The first part is to construct a expected travel time model of single-deep E-SBS/RS under single and dual command cycle.Considering the random storage,the single-deep E-SBS/RS performs single and dual command cycle running processes and characteristics respectively,and establishes an expected travel time model.The second part is to construct the expected travel time model of double-deep E-SBS/RS under single and dual command cycle.On the basis of the first part,the characteristics of double-deep E-SBS/RS are analyzed by comparing single-deep E-SBS/RS,and the travel time model of double-deep E-SBS/RS under single and dual command cycle is established.All the models were verified by Anylogic simulation.The third part is to comprehensively consider the expected travel time,system energy consumption and system configuration cost of E-SBS/RS,establish a multi-objective optimization model under single-deep and double-deep,and use the multi-objective particle swarm algorithm to solve the problem.For different warehouses,through change the corresponding parameter value,and give the result analysis of the corresponding number of shuttles and service level.By comparing the effect of lane depth,command cycle,shelf level division,and doubledeep E-SBS/RS filling state on the system travel time,the results show that: in E-SBS/RS,dual command cycle can effectively improve the retrieval efficiency of the system.Increase by about 26.54% under single deep and 27.96% under double deep.In the single-deep ESBS/RS,the utilization rate of the lift shuttle under the dual command cycle is higher,while in the double-deep E-SBS/RS,the opposite is true;In the high-density double-deep E-SBS/RS,dual command cycle can save the travel time,but the shuttle utilization rate under single command cycle is higher.By analyzing the multi-objective optimization results of expected travel time,system energy consumption and system configuration cost,it can be concluded that the travel time of E-SBS/RS is inversely proportional to the cost and energy,while the cost is directly proportional to the energy consumption,and the energy consumption increases faster than the cost;the minimum total time and the lowest energy consumption of the double-deep ESBS/RS are lower than the corresponding optimal value under the single-deep E-SBS/RS,but the minimum travel time is lower than that of the single-deep E-SBS/RS is high.The E-SBS/RS and the travel time models proposed in this paper and the conclusions in different scenarios can help warehouse managers and planners in system selection,system bottleneck analysis,storage strategy selection,command cycle selection,and operating efficiency,energy consumption and cost.Provide decision-making basis support for comprehensive index evaluation and other aspects.