Research On Configuration Problems Of Shuttle-based Compact Storage And Retrieval System

In recent years,new type storage systems have emerged one after another with the rapid development of intelligent logistics.As a new type storage system,the shuttle-based compact storage system has attracted much attention due to its low cost,small land area,high space utilization and flexible operation of the devices.Studying the configuration optimization problems of the shuttle-based compact storage system can improve the system operation efficiency and reduce the enterprise cost.This thesis studied the configuration optimization problems of two different shuttle-based compact storage systems.The specific research contents are as follows:According to the system operation procedure under the double command cycle?DCC?,this thesis classified the shuttle operation mode.Considering the problem of low utilization of the devices by placing a shuttle on each level of the storage racks,this article proposed to use a shuttle elevate for change-level operation of the shuttle.And the this thesis analyzed the operation process for the Shuttle-Carrier Compact Storage&Retrieval System?SC-CS/RS?and the Four-way Shuttle Compact Storage&Retrieval System?FS-CS/RS?under the DCC mode.According to whether there is a shuttle and the storage task and retrieval task at the same level,the operation of the shuttle under the DCC is divided into four sub-modes,namely DCC₁ mode,DCC₂ mode,DCC₃ mode and DCC₄ mode,and the four sub-modes were analyzed and described.Aiming at the configuration optimization problems of the SC-CS/RS,the multi-objective optimization model of the system configuration was proposed and established.This thesis established the Pareto multi-objective optimization model with the minimum system average throughput time and minimum total cost of system.And the mathematical model used the number of levels,the number of columns,the number of rows,the number of the unit racks,the number of shuttle-carriers,the maximum speed and acceleration of the cargo elevator,the maximum speed and acceleration of the shuttle elevator,the maximum speed and acceleration of the shuttle and the carrier as decision variables.Then the Pareto multi-objective optimization algorithm was used to obtained optimal solutions.And each solution of the Pareto frontiers can be used as the optimal configuration scheme for the SC-CS/RS.A multi-objective mathematical model for configuration optimization of the FS-CS/RS was proposed and established.The four-way shuttle is used for the storage and retrieval of palletized unit loads.The weight of the unit loads has a great influence on the running speed of the shuttle.Based on this feature,the goal of the configuration of the FS-CS/RS is considered in order to meet the high throughput performance of the system and reduce the investment cost and energy consumption cost for the enterprise.This thesis proposed a multi-objective optimization model with 15 variables such as three-dimensional dimensions of the storage rack,the number of change-layer shuttles and operational parameters of the machines.The Pareto solution set was obtained useing NSGA-II algorithm,and the non-dominated solution set was analyzed.The results of the analysis provided a reliable decision reference for designers of compact storage systems.Business decision makers can determine the three-dimensional size and the device configuration of the warehouse system based on their own propensity to target.