基于双向重力货架的高密度仓储系统管理与优化研究

Bi-directional flow-rack (BFR) automated storage and retrieval system (AS/RS) has high storage density to meet the increasing of land cost and the increasing of storage requirements. Such a system consists of a BFR and two storage/retrieval (S/R) machines. S/R machines are deployed to the two working faces of the BFR, respectively. Sloped bins make stored unit-loads slide from one end of each bin to the opposite end driven by gravity. In the BFR, bins in adjacent columns slope to opposite directions to let an S/R machine stores unit-loads to half bins and retrieves unit-loads from the other half bins on a working face. Therefore, S/R machines can work in the dual-command (DC) mode and blocking unit-loads are re-stored to the same working face directly. This proposal mainly studies the storage assignment, the sequencing of operations and the simultaneous performing of operation sequences. Based on the turnover information of unit-loads, storage assignment methods are proposed to balance the workload of the two S/R machines and allocate unit-loads to appropriate bins with appropriate orders to avoid blocking unit-loads. Based S/R locations of unit-loads, optimization model for DC operation generation can be established and high performance DC operation sequencing method can be designed to generate two DC operation sequences for the two working faces, respectively. Because S/R machines execute DC operation sequences simultaneously, the cooperation mechanism of S/R machines must be designed to make the good use of released idle segments for storing incoming unit-loads and re-storing removed blocking unit-loads to minimize the processing time of DC operation sequences. The research results of this proposal have important scientific significance and application value, which can be extended to the practical engineering applications.

双向重力货架系统是一种高密度自动存取系统，可应对不断增加的土地成本和库存需求。该系统由一个双向重力货架及部署在货架两个侧面的装卸机组成。倾斜的存储单元使得货物由于重力作用从存储单元一端滑向另一端。相邻列存储单元倾斜方向相反使得装卸机将货物存入工作面一半的存储单元并从另一半存储单元中取出货物。阻挡货物直接重存入同一工作面，装卸机采用双命令工作模式。本项目主要研究双向重力货架系统的存储分配、操作序列生成与并行执行。基于货物周转信息，设计合理的存储分配方法平衡装卸机工作量并合理分配货物以降低存取成本避免产生阻挡货物。基于货物的存入位置和提取位置，建立相应的操作生成模型，设计高效的操作序列生成算法为两个工作面各生成一个操作序列。基于装卸机并行执行的特点，设计合理的装卸机协同机制，压缩执行过程中装卸机停顿时间，提高操作序列并行执行的效率。本项目具有重要的科学意义和应用价值，可推广到实际工程应用中。

本项目考虑货物周转模式以及重力式高密度自动存取系统结构特点，设计存储分配算法用于建立货物-存储单元匹配关系以及操作生成算法基于货物存储分配结果生成存取操作。本项目分析了两种货物周转模式：分类存储策略和基于存放时长存储策略；四种重力式高密度自动存取系统：流式货架系统、双向流式货架系统、单机流式货架系统以及3D紧凑系统，结合货物周转模式和系统结构特点设计了相应的存储分配算法和操作生成算法。.分类存储策略中各种货物的需求量已知，货物按照周转速度划分为若干货物大类。货架上的存储单元按照离提取/放置点的距离远近划分为若干存储区。周转速度快的货物大类中的多种货物被分配到距离近的存储区以降低存取成本。本项目分析发现结合分区策略和InDeep策略可以建立适用于双向流式货架系统、单机流式货架系统以及3D紧凑系统分类存储策略的存储分配算法。且直接将阻挡货物重存入相邻的存储单元可以有效提高货物的存取性能。.存放时长存储策略中一个管理周期内所有货物到达和离开时间已知。基于已知的周转信息，分组-匹配方式在分组过程中将尽可能多具有先进先出关系的货物分配到同一个分组，在分配过程中将具有最多货物的分组与距离提取/放置点最近的存储单元进行匹配。仿真实验证实分组-匹配算法可以在极短时间得到重力式高密度自动存取系统的存储分配结果。.双向流式货架系统、单机流式货架系统以及3D紧凑系统同一个工作面既可以存入货物也可以取出货物。装卸设备在这些系统中可以采取双命令工作模式，即一次操作执行中存入一件货物并提取一件货物以降低装卸设备的总行驶时间。基于存放时长存储策略的存储分配结果，双命令操作生成算法基于已确定存取位置的货物生成高效的存取操作。双命令操作生成问题可以转化为存入位置与提取位置的指派问题，利用修改匈牙利方法的方式可以设计出高效的双命令操作生成算法。.接下来的工作是将项目的理论成果应用到实际中以及扩展成果的应用范围如用于高密度智能停车。

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