基于Robot输送的多层穿梭车仓储系统设计与性能分析

传统多层穿梭车存储系统(Multi-Tier Shuttle Warehousing System,MTSWS)中拣选台前端的输送线成为制约系统拣选效率的主要因素,为进一步增强多穿系统的灵活性,提高拣选效率,提出基于Robot输送的多层穿梭车仓储系统,首先设计该系统的组成设备、整体布局及拣选作业流程,然后运用开环排队网络(Open Queuing Network,OQN)建模方法,建立订单服务时间模型,从订单服务时间、Robot等待时间和Robot利用率等系统性能,进行订单到达率和Robot数量敏感度分析,发现当存储容量越大,订单到达率越高或变动幅度越高时,基于Robot输送的多层穿梭车存储系统的优势越明显。     

双深度多层穿梭车仓储系统并行作业及建模分析

为了解决传统顺序作业方式下,双深度多层穿梭车仓储系统存在的系统响应时间长和作业效率低等问题,在分析提升机和穿梭车并行作业的基础上,提出该类仓储系统的分离—聚合排队网络模型,并设计基于Cox-ian分布的近似分解算法进行求解.构建基于分离—聚合点的闭环排队网络模型,将各服务点的一般分布用Cox-ian分布替代,进而求解分离—聚合点的吞吐率;用单个服务点替代分离—聚合点,得到基于分离—聚合点的开环排队网络模型,并采用最大熵值法求解,得到系统性能指标.以实际案例的4种配置进行分析验证,结果表明所提模型可以较大幅度提升双深度多层穿梭车仓储系统的性能和作业效率.     

基于穿梭车的密集存储系统吞吐量优化分析

随着自动化技术及物联网技术的飞速发展,穿梭车在自动化密集存储系统中应用越来越广泛。文中根据单层作业的多层穿梭车系统的工作模式,提出了最近邻点法对存取订单序列进行匹配,比较使用算法前后对系统吞吐量的影响,以仿真实验的方式进行了数据分析。实验证明,使用最近邻点法后的穿梭车系统订单存取时间大大缩短,提高了系统的吞吐量。     

动态拣选系统下订单分批问题研究

对分区拣选系统研究在线订单分批策略.基于排队论角度,采用随机过程、随机服务系统的基本理论与方法,构建串行分区下订单不分批与订单固定时间窗分批拣选的随机服务系统模型,确定要研究对比的系统效率指标.在MAT-LAB R2019a软件环境下模拟在线订单到达情况,分析系统效率指标并找出分区拣选系统的最优分批策略.仿真验证结果表...     

快速箱输送系统的设计

以物流配送中心货到人拣选系统的快速箱输送系统为研究对象,通过对箱输送线系统的任务要求进行分析,确定快速箱输送系统的布局方案和作业流程,并根据系统布局和拣选需求,对多台输送设备合理选配,搭建出专业、可靠的输送线系统,辅以控制与检测装置,规划出料箱最优行走路径,保证输送环线快速、有序、准确地完成对料箱、订单箱的输送、缓存、排队和补货作业,达到系统的拣选效率要求。     

结合FJSP问题的跨层穿梭车仓储系统作业调度研究EI北大核心

为提高跨层穿梭车仓储系统的作业效率,通过分析系统内设备的服务时间,创新性地将柔性作业车间调度问题(FJSP)模型应用于解决跨层穿梭车仓储系统作业调度问题中,将穿梭车仓储系统中的出入库作业转化为FJSP中待加工的工件,同时考虑设备预先移动及并行情况,建立结合FJSP的跨层穿梭车仓储系统作业调度模型,并借助一种改进的灰狼算法,与传统的基于复合作业的调度模型进行对比。结果表明,所提出的结合FJSP问题的跨层穿梭车仓储作业调度出入库时间更短,模型通用性更高,能够有效地提高穿梭车仓储系统的作业效率。     

跨层穿梭车仓储系统复合作业路径规划

为提高跨层穿梭车仓储系统的运行效率,通过分析提升机与穿梭车的实际作业流程,考虑提升机与穿梭车加减速特性,建立出入库复合作业时间模型.为求解模型,设计了基于复合作业的改进人工鱼群算法,并通过算例验证了模型与算法的有效性.结果表明,所建立的跨层穿梭车仓储系统复合作业路径规划模型及所设计的求解方法,能够有效地减少其复合作业时间,提高出入库调度效率.     

随机订单驱动的集中式和分散式AS/RS建模及仿真

为了分析集中式和分散式自动存取系统与订单结构的适配性,在同时满足作业类型随机、订单时间随机和品规随机(作业储位随机)的条件下,通过分析设备运动轨迹、设备运动时间模型、作业时间构成及多作业间的时序关系,为两种系统建立作业时间模型;调整货架结构和订单密度两个参数,借助MATLAB仿真,研究货架结构和订单密度与两系统的适配性;构建作业效率和成本的系统评价多目标模型,并求得非劣解;结果表明,货架列数增加越多,分散式系统的并行作业效益越明显;随着订单密度的降低,分散式系统的并行作业效益也逐渐减弱;在长方形货架、订单密度较高情况下,分散式系统优于集中式系统;当考虑效率和成本双因素评价时,货架列数为100,层数为9层的分散式系统的优势最明显。     

多层穿梭车系统输送机缓存长度建模与优化

目前,多层穿梭车系统存在由于输送机缓存长度不合适,而导致出库阻塞或拣选空闲等问题,进而影响系统的整体效率。为提高系统作业效率,减少输送设备成本,在对多层穿梭车系统出库作业流程进行深入分析的基础上,建立输送机缓存输入输出平衡模型;在输送机缓存满足分拣作业正常运行的情况下,提出该缓存长度的最优条件及临界条件。运用开环排队网络建模方法对料箱出库作业流程进行分析,建立料箱平均出库时间模型,并根据料箱出库作业流量分布与人工拣选效率的关系,构建输送机缓存长度的优化模型;为缩短料箱平均出库时间,利用k-means聚类算法和储区排列规则对储位优化,进一步降低输送机缓存长度。仿真结果显示,优化后的品项分配与随机分配相比,补货缓存长度更趋合理,长度减少约12%。该研究一方面可指导规划设计人员对输送机缓存长度进行设计,另一方面可提高系统的整体作业效率,降低运营成本。     

穿梭车用伸缩货叉的设计研究

基于穿梭车的货到人拣选系统中,伸缩货叉是穿梭车上物料搬运的执行机构,它的合理设计是保证穿梭车轻巧、快速、精准的关键。文中进行伸缩货叉的研发设计,通过总体规划设计,确定伸缩货叉的性能参数;通过分析常用结构形式的弊端,合理设计伸缩货叉各部件结构,使伸缩货叉具有较大行程、足够强度的同时,结构先进合理,简单紧凑,外形尺寸小,方便选材,成本低,传动平稳,定位精确,易于操作,更加具有市场竞争力。     

Storage assignment optimization in a multi-tier shuttle warehousing system

The current mathematical models for the storage assignment problem are generally established based on the traveling salesman problem(TSP), which has been widely applied in the conventional automated storage and retrieval system(AS/RS). However, the previous mathematical models in conventional AS/RS do not match multi-tier shuttle warehousing systems(MSWS) because the characteristics of parallel retrieval in multiple tiers and progressive vertical movement destroy the foundation of TSP. In this study, a two-stage open queuing network model in which shuttles and a lift are regarded as servers at different stages is proposed to analyze system performance in the terms of shuttle waiting period (SWP) and lift idle period (LIP) during transaction cycle time. A mean arrival time difference matrix for pairwise stock keeping units(SKUs) is presented to determine the mean waiting time and queue length to optimize the storage assignment problem on the basis of SKU correlation. The decomposition method is applied to analyze the interactions among outbound task time, SWP, and LIP. The ant colony clustering algorithm is designed to determine storage partitions using clustering items. In addition, goods are assigned for storage according to the rearranging permutation and the combination of storage partitions in a 2D plane. This combination is derived based on the analysis results of the queuing network model and on three basic principles. The storage assignment method and its entire optimization algorithm method as applied in a MSWS are verified through a practical engineering project conducted in the tobacco industry. The applying results show that the total SWP and LIP can be reduced effectively to improve the utilization rates of all devices and to increase the throughput of the distribution center.     

Performance evaluation of AVS/RS under various design scenarios: a case study

In this study, performance evaluation of an autonomous vehicle storage and retrieval system (AVS/RS) is completed under various pre-defined design scenarios. Design scenarios are considered based on the rack configuration of the warehouse, namely the number of aisles, bays, and tiers, number of autonomous vehicles (AVs), and number of lifts. The system is simulated using ARENA 12—a commercial software. Seven performance measures are observed from the simulation results. These are: the average cycle time, average utilization of the AVs, average utilization of the lifts, average waiting time in the AVs’ queue, average waiting time in the lifts’ queue, average number of transactions waiting in the AVs’ queue, and average number of transactions waiting in the lifts’ queue. Total cost of the system is also integrated into the analysis. The results are analyzed via graphs. Various design options and their costs facilitate the evaluation of the best design for the warehouse manager. The case study is completed for a company that utilizes AVS/RS in France.     

自动小车存取系统中轨道导引小车环路死锁控制的研究

为防止自动小车存取系统中轨道导引小车环路死锁现象,提出了一种基于Petri网和有向图的死锁控制方法.该方法首先应用有色赋时Petri网建立了自动小车存取系统的动态模型,并结合有向图工具,阐述了导致环路死锁的原因.在此基础上,针对单一轨道双向运行的轨道导引系统,探讨了其环路死锁的主要表现形式,给出了轨道导引小车无死锁运行的充要条件,并提出了包含临界状态在内的死锁避免控制策略.最后,结合实例说明了环路死锁控制的有效性.     

Modelling and analysis of multiple cluster tools system with random failures using coloured Petri net

Semiconductor manufacturing is among the most complicated and expensive operation systems encountered today and multiple cluster tool system has become an important technology in semiconductor manufacturing systems with the advantages of higher yields and shorter cycle times. Modelling and simulation has become a standard methodology in order to understand and predict performance of semiconductor manufacturing systems. Resources random failures during process execution are one major concern regarding system performance measured in terms of throughput and cycle time. This study aims to models and analyse random failures of processing modules of multiple cluster tool systems using coloured Petri net method. The impact of different input factors on system throughput and cycle time is presented.     

An innovative automated storage and retrieval system for B2C e-commerce logistics

Flexible and timely warehousing activities provide a strong foundation for logistic systems. However, increasing B2C e-commerce with a variety of small internet orders may have a tremendous impact on warehousing. Automated storage/retrieval systems (AS/RSs) are a valid alternative for warehousing. Typical AS/RSs design and control problems in a static environment and cannot effectively manage parcel, small, and irregular items. This study proposes a new AS/RS that is more efficient and flexible for handling B2C e-commerce logistics. An auto-access multilevel conveying device (IMCD) with three-dimensional movement is integrated into the AS/RS. The ant colony system algorithm locates near-optimal routes for the IMCD. Typical travel distance/time measures evaluate the performance of an S/R device running on a warehouse floor. However, the performance index in this study looks at the IMCD’s travel time with three-dimensional movement in completing a batch order. To validate the new AS/RS, two simulation experiments were conducted to examine the effects of three-dimensional velocity and rack shape. Finally, this study compares a typical S/R system with the new AS/RS and makes recommendations for practical applications and further research.     

成批到达多服务台排队系统模型分析

研究顾客、服务员组成的排队系统中队长过程的随机比较问题,利用随机比较方法对服务系统进行分析,研究排队过程几个数量指标,对成批到达指数服务的多服务台排队系统模型进行分析,确定了顾客成批到达,服务时间及独立同分布,得到了该排队系统队长过程的随机比较以及队长函数关于时间的凹性和凸性。     

Stochastic capacity allocation, revenue management approach: the existence of modularity property

In the literature, although a few studies can be found regarding the application of revenue management to special cases of Make-to-Order manufacturing systems with stochastic capacity, there is not any study when capacity or demand (or both) are random variables with general distribution function. Therefore, in this paper, an approach is developed to study a more general case of Make-to-Order manufacturing systems based on the concept of revenue management. Due to the random nature of capacity and demand, the exact size of capacity to satisfy the orders is not known at the time of arriving orders. Consequently, the vital decision is either to accept or reject an order at the time of arrival. If an order is accepted but later rejected due to the lack of capacity, a penalty has to be paid to the customer. On the other hand, an order can be rejected by anticipating the capacity shortage at the time its arrival, while there will be some unused capacity at the processing stage. Then, this also results in the loss of revenue. We assume there are two classes of customers. The price paid by the customers of each class or the penalty paid to them is different from those of the other class customers. Although the objective function which represents the expected total revenue is not necessarily concave, this study demonstrates that it has unimodal property and as a result the existence of an optimal solution is guaranteed. This property has been proved previously for special cases where demand or capacity is continuous random variable. This study confirms this property also holds in more general cases. The proposed approach for a variety of scenarios, discrete and mixed random variables, is investigated by simulation techniques.     

Development of a framework for pick-and-pass order picking system design

In today??s competitive scenario of increasingly faster deliveries and smaller order sizes, a solution that is being used more frequently is the pick-and-pass Order Picking System (OPS). The purpose of this study is to define a framework for the pick-and-pass system design, by expanding previous literature on this topic. The framework aims at minimising the overall picking costs while respecting the required service level (i.e. order throughput time), and can be easily applied to the selection stage of OPS design. The number of zones and the number of pickers per zone are among the main project data for the framework application. Analytical models are used to estimate the travel distance, and network queuing theory to analyse the mean order throughput. On the basis of the proposed framework, pick-and-pass system performance is examined as a function of two typical design conditions: order size and number of items.     

具有AGV和AS/RS的装配线物流系统分析

阐述了具有自动导引车(AGV)和自动存取系统(AS／RS)的物流系统的工作流程，建立了该类物流系统的排队网络模型，分析了系统的性能与系统设计参数之间的关系，为设计具有AGV和AS／RS的复杂物流系统提供依据。     

自动化立体仓库双梭堆垛机作业时间及系统吞吐性能

分析了堆垛机作业时间的影响因素及系统吞吐性能;建立了多种情况下双梭堆垛机作业时间期望和方差的数学模型以及多种情况下双梭堆垛机自动存取系统的作业周期数学模型。