Travel-time models for flow-rack automated storage and retrieval systems

In this paper, closed-form travel-time expressions for flow-rack automated storage and retrieval systems are developed. The expressions, which are based on a continuous approach, are compared for accuracy, via simulation, with exact models which are based on a discrete approach. There is no significant difference between the results obtained from the continuous-approach-based closed-form expressions and the ones from the discrete-approach-based exact solutions. The closed-form expressions are easy to calculate due to their simplistic forms, even without a computer, while the exact solutions are extremely complex. On the basis of computation time, the proposed closed-form expressions are extremely practical when compared with the discrete-approach-based expressions, which require extensive computation time. The closed-form travel-time expressions developed in this study can be used to (1) establish performance standards for existing AS/RS, (2) evaluate throughput performance for flow-rack AS/RS alternative design configurations, and (3) compare different storage techniques for improved system performance. Due to their simplistic, yet accurate, definitions, the closed-form expressions, as well as the results of this study, are applicable to industry.     

Energy efficiency model for the mini-load automated storage and retrieval systems

In this paper, the energy efficiency model for the mini-load AS/RS is presented. As the existing models of AS/RS apply to already well-known objectives (minimum travel time, maximum throughput and minimum cost), the energy efficiency model for the mini-load AS/RS is proposed and discussed. According to global trends in material handling and warehousing, the design process should encompass not only the application of the equipment with fastest drives but should also consider the energy and environment aspect on the installed equipment. The proposed energy efficiency model for the mini-load AS/RS enables reduction of energy consumption and consequently the CO₂ emission, which is good from the economic and environmental point of view. We sincerely hope that the energy and environment aspect will indubitably bring changes into planning of warehouses and will mean great challenge for those who are engaged in the planning process.     

多模式自动化存取系统存储货位分配算法研究

针对多模式自动化存取系统的物资存储和上下架作业特点,讨论了物资入库上架的作业规则和流程,以物资下架出库作业效率为优化指标进行了入库上架过程的托盘物资存储货位分配。为适应密集存储作业特点,系统通过"制定货道分配计划→动态确定存储货道→穿梭板运送托盘物资进货位"3个步骤完成托盘物资存储货位分配和入库上架作业。在制定货道分配计划时,采用物资下架出库作业时间作为每条货道的下架出库作业效率评价指标,结合物资出入库周转频率求解最优货道分配计划,从而在不改变货架内原有托盘物资存储位置的条件下使制定的货位分配策略和物资存储方案达到最优。     

基于以太网的自动化仓库设备监控协议的设计

分析了自动化仓库设备堆垛机的监控要求及其工作状态的变化过程,设计了基于以太网的自动化仓库设备监控协议。该协议可实现设备故障再启动后自动恢复执行的功能。现场应用表明该设计提高了监控系统的自动化程度。所述的设备监控协议可扩展应用于多操作步骤的生产设备监控系统。     

自动化仓库堆垛机高速运行控制技术

以激光测距技术作为巷道堆垛机的认址手段,开发并应用变频器无级调速闭环控制方式,提出一种新型巷道堆垛机高速运行的控制方法,实际应用表明有关技术方法切实可行。     

面向仓储物流的建模及控制系统设计方法

为提高现代企业仓储物流的设计质量和效率,提出了一种基于资源颜色时序信号的扩展Petri网建模及控制系统设计方法.该方法首先采用资源颜色时序信号的扩展Petri网建立了仓储系统的动态模型,清晰地描述了各种物流活动的顺序、并发,冲突等关系,并结合关联矩阵,阐述了判断死锁和陷阱的方法.该方法建立的模型可根据Petri网运算规则进行保性化简,便于仿真分析和验证,且可直接用于系统可编程逻辑控制器的控制程序设计.最后,以仓储物流控制系统为例,阐述了系统建模及控制设计过程.     

立体仓库自动存取系统的作业周期与货位分区管理

通过对自动化立体仓库存取系统作业周期的计算,在周期和货位之间建立一种对应关系,根据需要可将库区货位分成不同的区,为仓库的经济设计和高效管理提供了依据。     

堆垛机异常状态检测与自恢复能力的研究

讨论了巷道堆垛起重机在运行过程中常见异常状态的检测、分析与处理 ,提出了异常状态分级的概念 ,并着重说明在异常状态发生后如何进行智能化处理 ,使堆垛机自动恢复正常状态。结合实际应用 ,介绍了堆垛机异常状态检测与处理的程序结构     

A multi-stage heuristic algorithm for matching problem in the modified miniload automated storage and retrieval system of e-commerce

E-commerce, as an emerging marketing mode, has attracted more and more attention and gradually changed the way of our life. However, the existing layout of distribution centers can't fulfill the storage and picking demands of e-commerce sufficiently. In this paper, a modified miniload automated storage/retrieval system is designed to fit these new characteristics of e-commerce in logistics. Meanwhile, a matching problem, concerning with the improvement of picking efficiency in new system, is studied in this paper. The problem is how to reduce the travelling distance of totes between aisles and picking stations. A multi-stage heuristic algorithm is proposed based on statement and model of this problem. The main idea of this algorithm is, with some heuristic strategies based on similarity coefficients, minimizing the transportations of items which can not arrive in the destination picking stations just through direct conveyors. The experimental results based on the cases generated by computers show that the average reduced rate of indirect transport times can reach 14.36% with the application of multi-stage heuristic algorithm. For the cases from a real e-commerce distribution center, the order processing time can be reduced from 11.20 h to 10.06 h with the help of the modified system and the proposed algorithm. In summary, this research proposed a modified system and a multi-stage heuristic algorithm that can reduce the travelling distance of totes effectively and improve the whole performance of e-commerce distribution center.     

自动化立体仓库堆垛机精确控制技术的研究

介绍自动化立体仓库的系统组成结构、工作流程、位置控制技术。结合机电一体化技术,完成了自动化立体仓库巷道堆垛机行走机构、升降机构、伸缩货叉机构PLC控制系统设计。着重说明PLC在自动化立体仓库堆垛机精确控制方面的应用。     

基于风险的维修决策在立体仓库中的应用

在风险的维修决策方法的发展和实施步骤的基础上,针对自动化立体仓库运行中存在的风险,选取堆垛机为研究对象,提出了将基于风险的维修决策应用于物流设备的技术框架.该框架运用故障树算法,综合考虑设备可靠性和故障后果,对堆垛机的风险进行定量分析,并利用风险为决策目标建立维修策略,以降低堆垛机的运行风险.研究表明:基于风险的维修方法是一种可以优化维修计划的有用的决策工具,并可以应用到物流设备.     

Simultaneous optimisation of control factors in automated storage and retrieval systems and FMS using stochastic coloured Petri nets and the Taguchi method

Automated storage and retrieval systems (AS/RS) are playing an important role in modern manufacturing systems such as flexible manufacturing systems (FMS). The integration of AS/RS systems and FMS is very complex owing to the complexity of the individual elements. Stochastic coloured petri nets (SCPN) can be used to model, simulate and analyse such a system efficiently and realistically. In this paper, SCPN based simulation, aided by the Taguchi method of design of experiments, has been used for analysing the influence of important factors on makespan, unproductive travel time, and the mean flow time, and is supported by an example.     

垂直循环机械式停车设备的调车方法

确定合理的调车方法是机械式停车设备控制系统软件设计的基础。以采用MCS—51系列单片机构成的停车设备控制系统为例,分析说明了停车设备存取车时拖动电机旋转方向和托架转过的车位数的确定方法,以及存取车后车位空／满标志位和车辆所在车位号的更新方法。     

行驶时间延迟的物流配送干扰管理模型及算法

针对物流配送过程中某路段行驶时间延迟而导致物流配送计划无法实现的难题,运用干扰管理方法,从客户满意度、驾驶员满意度和配送成本三方面衡量物流配送系统的扰动程度。针对带有时间窗的物流配送车辆路径问题,建立了目标规划数学模型,设计了用于求解该类问题的一种遗传算法,该算法采用二维染色体结构,以及适合多目标决策模型的适应值计算方法。最后,通过算例验证了所提干扰管理模型及算法的有效性。     

Synthesis of feedback control elements for discrete event systems using Petri net models and theory of regions

This paper describes a method for constructing a Petri-net-based controller for a discrete event system (DES) modelled by a Petri net. Assuming that an uncontrolled Petri net model of the DES and a set of forbidden state specifications are given, feedback control elements, i.e. a set of places and related transitions, with initial marking, are computed using the theory of regions, which is a formal synthesis technique for deriving Petri nets from automaton-based models. When feedback control elements are added to the uncontrolled Petri net model, the controlled (closed-loop) Petri net model of the system is obtained. The controlled Petri net model obtained is maximally permissive while guaranteeing that forbidden states do not occur. The proposed method is computationally efficient and does not suffer from the state explosion problem. Two examples are provided to show the applicability of the proposed method.