Automated system for scheduling pipeline time for small batch production using a symphony spreadsheet

A scheduling pipeline program can be easily developed and customized using Symphony spreadsheet software. Monsanto Research Corporation produces small electro-mechanical component subassemblies in large lot sizes which are subdivided into transfer quantities. Since production takes place in several buildings, the transfer quantities create wait time for parts not being worked. Batch production schedules are constructed and adjusted using the pipeline program. This application uses work centers and/or balanced workstation assignments to determine schedule dates for a given transfer quantity. Production routing information is summarized for each station assignment, and these are considered as schedule points. The program incorporates many data base management, input forms, and graphic features available in Symphony.     

Spreadsheet calculations for the machine interference queueing model

The machine interference queueing model has numerous applications in different areas. Yet it is seldom used due, mainly, to the complexity of the associated calculations. In this paper, a simple and easy-to-implement spreadsheet application of the model is presented. This application calculates state probabilities and mean values for key parameters: machine utilization, operators’ load and system throughput. The application is parametric in the numbers of machines and operators, mean time between (machine) failures, and mean service time. This facilitates model analysis and turns the spreadsheet application into a powerful tool for analysis, design and decision support.     

A closed-loop control architecture for CAM accounting for shop floor uncertainties

The primary focus of this paper is to demonstrate an enhanced closed-loop computer-aided manufacturing (CAM) architecture using a Petri net based analysis mechanism, which incorporates shop floor uncertainties to generate process plans and alternative processing sequences under dynamic conditions such as machine failures. Modern CAM software provide efficient, error-free, and user-friendly interfaces to develop processing sequences for manufacturing tasks. However, their effective scope is still limited from the post-process planning stage to the pre-machining stage. These types of software fail to incorporate the variability encountered in an actual shop floor to develop effective process plans. This is caused due to CAM software’s limitations in input handling mechanisms, limited simulation functionality, and inability to handle complex process variability from the shop floor. In this paper, CAM functionality is augmented with Petri net models to capture alternative process plans and shop floor variability arising due to equipment failures, repairs, and setups. The output from the analysis of the Petri net model provides a better understanding of the process characteristics and provides information to the CAM system to adapt to shop floor variability. The resulting information from the Petri net model allows the CAM system to compare alternative process plans while taking shop floor information into account. This mechanism can result in better decisions, reduced processing times, and better overall resource utilization, and provide alternative process plans based on current resource information.     

Scheduling flow shops in the environment of multi-functional machine tools

The concept of virtual machine tool (VMT) is introduced in this paper to specify machining resources of multi-functional machine tools. A two-level model for makespan minimization in a flow shop is developed in multi-functional machine tool environments. The model is first optimized with an Hopfield neural network to find the optimal processing sequence for components to visit all the necessary VMTs. Secondly, according to a set of shop floor control rules, the VMTs for components machining are matched with real machine tools. This procedure is driven by the events taking place in components machining, such as the arriving or the finishing of a component. Numerical experiments are conducted in a number of flow shop scheduling problems up to 8×8 and the mean relative optimizing rate is employed to assess the results of numerical experiments.     

基于面向对象的虚拟数控系统的研究

提出了虚拟数控机床的基本系统结构,引入面向对象程序设计的基本概念于虚拟数控机床的设计.根据数控机床各零部件在加工过程中的特点,把它们分成静态类、运动类和动态类3类.在此基础上,利用3维实体CAD（computer aided design）软件系统进行虚拟数控机床加工过程中非变形物体（静态类与运动类）的外形设计并转换成STL（stereolithography）文件,对动态变形物体采用特征造型方法,与设计的成员函数即该零部件的运动函数有机地集成起来,构成类,最终实现数控机床各机构的动态仿真.引入了四元数的基本概念,并将其应用于系统设计与实现.上述方法为虚拟数控系统的研究提供了基本框架.实验结果证明,上述方法是可行的,具有很好的实用价值和参考价值.     

PLC在组合机床控制中的应用

本文介绍了PLC对组合机床的控制,分析了其工作原理,详细介绍了其硬件配置和软件设计.     

一种适用于踏步机的游戏设计

为了使大众能方便地在室内进行健身,根据市场上已有的踏步器为蓝本,设计一款适用于踏步器的游戏系统,它溶健身娱乐为一体,适合现代人的生活方式.该系统由三部分组成：踏步器、传感装置和计算机.传感装置由两个霍尔传感器、MAX232串口芯片和STC89C52单片机组成,霍尔传感器用来感应玩家踏板动作,单片机用于计算左、右步频并发送步频,串口芯片将左、右步频数据传给计算机;计算机负责游戏软件的运行和显示.游戏软件的设计原理是：左、右步频的平均值可用来决定游戏主角的移动速度,步频差决定它的移动方向.改编了“贪吃蛇”游戏作为测试软件,在游戏中添加了运动控制和健身功能,经过测试能达到预期的设计效果.该游戏系统具有制作成本低、操控方便、通用性强等特点,具备一定的市场开发潜力.     

虚拟机软件结合LoadRunner的一种测试方案探讨

基于虚拟化技术进行软件自动化测试是测试主流技术发展的一个方向。介绍了虚拟机软件VMware结合测试工具软件LoadRunner的一种软件测试方案,详细介绍了测试方法、测试环境、测试用例以及数据处理方法。通过对同一B/S系统在真实环境和虚拟环境中进行对比性能测试,并基于实测数据加以分析,论证了该方案的优越性,得出了能否应用的结论。     

数控龙门铣床数据采集系统综述

龙门铣床是机床族的重要机型,其应用广泛,尤其是数控龙门铣床在航空制造领域的地位举足轻重。数据采集系统是机床监控系统的前端子系统和关键组成部分,数据采集系统设计的成功与否,决定了机床监控系统的数据有效性。对应用于龙门铣床的数据采集系统进行研究,具较大的现实意义。在介绍数控龙门铣床的结构及功能的基础上,分析了数控龙门铣床的数据采集的核心需求,针对性地分析和总结了数据采集的手段和方法,并概述了数控龙门铣床数据采集系统的发展方向。为数控龙门铣床数据采集系统的设计提供了技术支撑。     

Model-based diagnosis of spreadsheet programs: a constraint-based debugging approach

Spreadsheet programs are probably the most successful example of end-user software development tools and are used for a variety of purposes. Like any type of software, they are prone to error, in particular as they are usually developed by non-programmers. While various techniques exist to support the developer in finding errors in procedural programs, the tool support for spreadsheet debugging is still limited. In this paper, we show how techniques from model-based diagnosis can be applied and extended for spreadsheet debugging by translating the relevant parts of a spreadsheet to a constraint satisfaction problem. We additionally propose both problem-specific and generalizable extensions to the classical diagnosis algorithms which help to detect potential problems in a spreadsheet based on user-provided test cases more efficiently. The proposed techniques were integrated into a modular framework for spreadsheet debugging and evaluated with respect to scalability based on a number of real-world and artificially created spreadsheets. An additional error detection exercise involving 24 subjects was performed to assess the general applicability of such advanced spreadsheet debugging techniques for end users.     

Improving the performance of cellular manufacturing by a dynamic part assignment approach

In this paper, a simple dynamic part assignment (DPA) procedure is introduced and its effects on the performance of cellular manufacturing systems is evaluated. In this procedure rerouting of parts among machine cells is allowed for better machine utilization. Three data sets are used to compare the performance of manufacturing systems under job shop and cellular manufacturing when DPA is employed. The results of simulation runs indicate that the proposed DPA method improves the performance of cellular manufacturing significantly by reducing the congestion in machine cells with long waiting lines.     

Design of cellular manufacturing systems—An industrial case study

This paper discusses the development of a cellular manufacturing system in a manufacturing company. A new clustering algorithm has been applied to the design of the system. The algorithm consists of two parts, a cluster-seeking process and the minimization of bottleneck machines. Two parameters are input by the user: (a) the desired number of machine cells or part families, and (b) the minimum number of parts within each cell or part family. A number of cells have been designed for a preparation shop, a fabrication shop, and a machine shop. Both the advantages and disadvantages of the algorithm have been analyzed, especially concerning its applications to industry.     

LabVIEW6.i实现TCG16数控机床试验波形的采集分析

介绍了利用LabVIEW6.i及其附加软件工具包(Sound and Vibration Toolkit和SQL Toolkit)对TCG16数控机床试验波形进行实时数据采集、监控以及对离线数据的精密分析和处理.     

Linguistic extension of abstract machine modelling to aid software development

The traditional use of abstract machine models is to provide a conceptual framework for software design and to aid portability and machine independence. Access to the abstract machine model from the higher-level system on which it is based provides a powerful tool for software development. This paper describes a technique in which the higher-level system is interfaced to the underlying abstract machine, thus allowing use of the higher-level system to analyse and debug its own implementation. The application of this technique in the implementation of SL5 is given as an example. Experience with the use of the facility and a discussion of basic design considerations are included.     

Workload vs scheduling policies in a dual-resource constrained job shop

The purpose of this paper is to report on research conducted to examine the effectiveness of different scheduling policies in a dual-constrained job shop under various workload conditions. The standard assumption in most job shop scheduling research has been that a 90% utilization of the shop is achieved. However, since shop utilization levels vary widely, it was hypothesized that scheduling policies that are optimum under one load condition might not be as effective under other load conditions. The model for this simulation experiment represented a job shop constrained by both labor and machines. The shop contains four machine centers with random routing of jobs through the shop. Shop workload was defined at three levels: 70, 85 and 99% utilization. Four machine scheduling rules and three labor assignment rules were tested for each of the shop workload levels, with mean job flow time as. the performance criterion. The results of the 3 × 4 × 3 factorial experiment showed that the advantage of the SPT (shortest processing time) machine scheduling rule over other rules is diminished dramatically when shop utilization is reduced from 99 to 85% or below. This same observation holds for other rules considered. The LNQ (longest queue length) labor assignment rule outperformed other rules at the 99% utilization level, but yielded no significant difference in performance at the 85% and below workload levels.     

基于LabVIEW数控机床几何误差补偿的研究方法

介绍一种由软件、硬件控制的数控机床几何误差补偿。误差补偿的原理主要是运用多体系统运动学理论建立机床几何误差模型,用硬件控制固化在程序存储器内的误差补偿程序完成补偿任务,并通过RS-232C实现数控机床与Windows平台通信与数据交换。     

数控机床远程智能故障诊断系统设计

为了解决机床远程故障诊断中有线网络布线干涉、设备成本高等问题，同时满足大数据存储、多样化数据接入的需求，提出基于物联网(The internet of things,IoT)无线网络和IoT云平台的故障诊断系统。系统模型设计为4层：采集层、传输层、运算层和应用层。采集层采用基于应用过程的对象连接与嵌入(Object linking and embedding for process control,OPC)和多传感器融合的数据采集方法，获得故障诊断所需数据；传输层基于窄带物联网(Narrow band internet of things,NB-IoT)无线通信技术和IoT云平台，实现数据远程传输、通信和存储；运算层基于BP神经网络在前、专家系统在后的串行反馈控制机制，建立故障诊断算法模型。以机床的主轴伺服系统为实例，分析其故障现象并获得故障样本，对诊断算法模型进行误差仿真分析，预测结果与期望相吻合，验证了该模型的有效性。     

Distributed bottleneck control for repetitive production systems

A bottleneck control problem for general periodic job shops with blocking where each machine has an input buffer of finite capacity is investigated. The job shop considered consists of a set of workflows competing with each other for access to common machines. A distributed buffer control policy that restricts a job entering an input buffer of a local machine in a specific sequence is proposed. The conditions sufficient for design and allocation of dispatching rules are presented. The system time and the rate of machine utilization are considered as the evaluation criteria. Finally, the procedure aimed at scheduling periodic job shops is provided.     

A neuro-genetic approach to design and planning of a manufacturing cell

In this paper, we propose a neuro-genetic decision support system coupled with simulation to design a job shop manufacturing system by achieving predetermined values of targeted performance measures such as flow time, number of tardy jobs, total tardiness and machine utilization at each work center. When a manufacturing system is designed, the management has to make decisions on the availability of resources or capacity, in our setting, the number of identical machines in each work station and the dispatching rule to be utilized in the shop floor to achieve performance values desired. Four different priority rules are used as Earliest due date (EDD), Shortest Processing Time (SPT), Critical ratio (CR) and First Come First Serve (FCFS). In reaching the final decision, design alternatives obtained from the proposed system are evaluated in terms of performance measures. An illustrative example is provided to explain the procedure.     

基于虚拟DPU技术的DCS仿真软件设计开发

采用虚拟DPU技术对Symphony集散控制系统实现了DCS分散处理单元数学模型的仿真.该软件将实际分散控制单元中的DPU功能移植过来,脱离了硬件设备,实现DPU工作过程的模拟.其中,虚拟DPU算法块在Visual C 6.0高级编译环境中开发.该方法保证了DCS系统的仿真精度及准确性,又增强了系统的可移植性和可扩展性.