机电-自动化控制类-英文文献

精选优质文档-倾情为你奉上Theoretical Computer Science 253 (2001) 6193Developing a Hybrid Programmable Logic Controller Platform for a Flexible Manufacturing SystemHenning Dierks 1University of Oldenburg, Fachbereich Informatik, Postfach 2503, 2900 Oldenburg, GermanyAbstract: In this article, we present the design and implementation of a flexible manufacturing system (FMS) control platform based on a programmable logic controller (PLC) and a personal computer (PC)-based visual man-machine interface (MMI) and data acquisition (DAS) unit. The key aspect of an FMS is its flexibility to adapt to changes in a demanding process operation. The PLC provides feasible solutions to FMS applications, using PC-based MMI/DAS, whereby PLCs are optimized for executing rapid sequential control strategies. PCs running MMI/DAS front-ends make intuitive operation interfaces, full of powerful graphics and reporting tools. Information from the PC can be distributed through a companys local area network or web using client-server technologies. Currently, with the convergence of underlying microprocessor technology and software program-ming techniques, many users find that PLCs provide a cost-effective solution to real-time control in small- to medium-sized process plants, especially when combined with supervisory PCs using hybrid systems. The major work of this article demonstrates that PLCs are responsive to rapid and repetitious control tasks, using PCs that present the flow of information automation and accept operator instructions, thereby providing the user a tool to modify and monitor the process as the requirements change.Key Words: PLC、FMS、PC.1IntroductionIn a variety of product manufacturing industries, the most automated form of production is a Flexible manufacturing system(FMS),first introduced in 1970s. Since the FMSs can providea high potential for productivity improvement in batch manufacturing, the number of FMSs is growing substantially (Groover and Zimmers, 1984). The acceleration throughout the world is due to increased global competition, reduced manufacturing cycle times, and cuts in production costs.Generally, an FMS consists of a group of machines or other automated work stations, which form into modular subsystems, such as CNC machines, robots, vision systems, and a process station. These are interconnected by a materials handling system and usually driven by a computer(Maleki,1991).Each modular system requires an individual modular control system, with different components being controlled by individual controller units. All of the modular subsystems are controlled by computers as usual. These controllers perform their intended tasks under supervision of a higher level controller. To the system, both the control devices as well as the flow of information need to be automated. The key aspect of an FMS is its ability to adapt to changes in the control tasks. This flexibility includes the quantities and varieties of part types which it can produce, the order in which operations may be performed, and its ability to reroute parts back into flow paths. In the end, the control platform should have the capability to automate the flow of information.Typically, there are three types of control platforms used in FMSs: minicomputers, microcomputers, and PLCs (Maleki, 1991). The minicomputers are best suited for complex large-scale, continuous ,regulatory control applications . The PLCs are used for rapid and repetitious logic control. Personal computers (PCs) are suited for operator interface functions. Primarily, PLCs are designed to replace hardwiring relays, to operate in an industrial environment, to be easily modified by plant engineers and maintenance personnel, and to be maintained by plant electricians. Currently, with the convergence of underlying microprocessor technology and software programming, many users find that PLCs provide a cost-effective solution to real-time control in small-to medium-sized process plants, especially when combined with supervisory PCs using hybrid systems.The purpose of this article is to address the state-of-the-art technology of FMSs. The design and construction of an FMS using PLC-controlled and PC-based visual man-machine interface(MMI) and data acquisition system(DAS) are presented. It is organized as follows. Section 2 begins with the description of the FMS on the factory floor of the Center for Manufacturing System sat the NewJersey Institute of Technology(NJIT).Section 3 shows the operational description of the FMS. Sections 4 and 5 present the applications of PLC-controlled and PC-based MMI/DAS for the FMS at NJIT. Section 6 contains a summary of the advantages of this PLC-controlled and PC-based MMI/DAS for FMS application.2. Description of the FMSSI handling conveyor systemThis consists of four carts, A, B, C, and D, with fixtures mounted on each, two transfer tables,TT1 and TT2 , and dual conveyors which transport materials to each workstation.Figure 1. Flexible manufacturing system.NASA II CNC milling machineThe milling machine accepts rectangular solid blanks and machines each part of different types according to its computer controller.GE P50 robotA shared robot is used to load and unload the material between the CNC milling machine and the conveyor system, and between the parts presentation station and conveyor system. It contains five computer programs assignable by the PLC. The computer programs direct the robot to load the material between the parts presentation station and the carts and between the CNC machine and the carts. The last two programs place the completed parts in the accept or reject area.Parts presentation stationThis station includes a gravity-chute, which supplies rectangular solid blanks as raw materials. This station also contains two bin types, one each for accepted parts and rejected parts.Computer vision systemThe vision system provides for the visual automated inspection of the parts. It is a menu-driven, 64-level gray scale, edge detection system.Drilling machineAn IBM7535 industrial robot with an automated drill as an end-effector drills various holes in the parts as directed.In summary, the FMS has two robots, one CNC mill, a material transfer convey or system including transportation carts and positioning limit switches, and a vision system, which are supervised by a GE-Series Six PLC and monitored by a PC-based visual MMI/DAS.3. Operational descriptionThe working cycle for this FMS proceeds in the following manner:1.Initially, all four carts on the conveyor system are empty and available for the raw materials to be loaded onto them from the parts presentation station.2.The GE robot loads four parts, one by one, on to the four carts on the convey or system. The carts move clock wise as they are being loaded.3. Figure 2 shows the positions acquired by the four carts once the four parts of different types have been loaded.4. The IBM robot drills various holes on each blank part as the cart stops at the drilling machine.5. The GE robot moves to the conveyor, removes the part from the cart at position X1,and loads it into the fixture located on the CNC machine table.6. Once the part is loaded on the CNC milling machine, the robot retracts, and the milling machine mills the rectangular part as required.7. After the milling operation, the robot arm moves to the milling machine to remove the part that was machined from the holding fixture.Figure 2. Loading state of the conveyor system.8. The robot returns the finished part to the same cart on the conveyor.9. A signal is sent to the vision camera to inspect the part.10. The vision system analyzes the part and outputs a signal that directs the robot to accept or reject the part.11. The robot runs either an accept program to place the part in the accept bin or runs a reject program to place the part in the reject bin.12. The GE robot goes to the parts presentation station and loads a new blank part into the cart.13. The cart is released to the system and the next cycle is started.4. Control of an FMS with a PLCThe significant features of the FMS control system are as follows:1.The system is easy to configure and to modify to accommodate changes and updates, because of the ladder logic capability of the system.2.In a similar manner, the system is easy to program and document.3.The system can be easily maintained, and troubleshooting is decreased because on-line diagnostics are provided to pinpoint problems and decrease maintenance.4.Naturally, the system is readily interfaced with the computer.The PLC is a general purpose industrial computer which is widely used in industrial process control. It is capable of storing instructions to implement control functions such as sequencing, timing, counting, arithmetic, data manipulation, and communication to control industrial machines and processes. The PLC is chosen to perform an FMS control task based on the following features:1) good reliability;2) less space required and operates in an industrial environment;3) easier to maintain by plant engineer or technician;4) can be reprogrammed if control requirements change;5) can communicate and network with other computers.In this application, a GE-Series Six PLC is equipped with a memory bank, and the I/O racks are loaded with the following input and output interfaces: 120 VAC input modules with 8 ports/module, 24 VDC input modules with 8 ports/module, and 120 VAC output modules with 8 ports/module.5. PC-based visual operator interface unitWith the convergence of microprocessor technology and software techniques, the PC has become very useful in operator interface applications. PCs running MMI/DAS front-ends make powerful, intuitive operation interfaces, full of useful graphics and reporting tools. Information from these PCs can be distributed through a companys local area network(LAN) or web using client-server technologies.A PC-based visual MMI/DAS was developed to monitor the process and log data. The functions of the MMI are twofold. First, it opens a window between the operator and the process and then displays the process information on the CRT. It also allows the operator to modify the time delay constants or alarm setpoints without changing the ladder logic, if the production requirements change. Second, it provides an automatic data logging device. It is capable of creating batch, shift, and day log reports. Information from the PC can be distributed through the local area network using client-server technologies. An application program has been developed by using an off-the-shelf state-of-the-art GENESIS for Windows PC-based software to provide the data from the PLC through a RS232 interface. This approach allows the PC to combine the controller, the programming terminal, the operator interface, and the data acquisition system together in one unit. The PC-based MMI/DAS software provides an icon-based and mouse-driven open system for designing a real-time control strategy and dynamic operator displays. With the open architecture features, it provides support for user algorithms and LAN interfacing.The other part of the MMI/DAS software is the enriched and user-friendly graphic builder. The graphic builder is an object-oriented CAD-based tool. The graphic tools allow the user to generate intuitive and useful man-machine interface screens to display the dynamic status of the FMS.6. ConclusionsThe particular FMS example is fully automated by a hybrid control platform using a PLC controlled and PC-based supervisory operator interface unit and data acquisition system. The trend of flexible manufacturing demands more open system control and flexibility with affordable cost. Obviously, the size and the nature of the application affect the decision. This PLC and PC hybrid supervisory control platform provides a cost-effective solution to real-time control and automation of the flow of information for small- to medium sized process plants. The system improvements are achieved in control system reliability, equipment maintainability, software maintainability, and system flexibility. The automated DAS system has the capability to generate batch, shift, and day logs reports, to report process and equipment alarms, and to refresh process data.References1 R. Alur, C. Courcoubetis, D. Dill, Model-checking for real-time systems, 5th Annu. IEEE Symp. onLogic in Computer Science, IEEE Press, New York, 1990, pp. 414425.2 R. Alur, D.L. Dill, A theory of timed automata, Theoret. Comput. Sci. 126 (1994) 183235.3 R. Alur, T. Henzinger, E. Sontag (Eds.), in: Hybrid Systems III, Lecture Notes in Computer Science,vol. 1066, Springer, Berlin, 1996.4 J. Bengtsson, K.G. Larsen, F. Larsson, P. Pettersson, Wang Yi, Uppaal a tool suite for automatic veri cation of real-time systems, in: R. Alur, T. Henzinger, E. Santag (Eds.), Hybrid Systems III,Lecture Notes in Computer Science, vol. 3, Springer, Berlin, 1996, pp. 232243.5 D. Bosscher, I. Polak, F. Vaandrager, Veri cation of an audio control protocol, in: H. Langmaack, W.-P. de Roever, J. Vytopil (Eds.), Formal Techniques in Real-Time and Fault-Tolerant Systems,Lecture Notes in Computer Science, vol. 863, Springer, Berlin, 1994, pp. 170192.6 J. Bowen, C.A.R. Hoare, H. Langmaack, E.-R. Olderog, A.P. Ravn, ProCoS II: A ProCoS II Project Final Report, Chapter 3 Number 59 in Bulletin of the EATCS, European Association for TheoreticalComputer Science, June 1996, pp. 7699.7 C. Daws, A. Olivero, S. Tripakis, S. Yovine, The tool Kronos, in: R. Alur, T. Henzinger, E. Santag (Eds.), Hybrid Systems III, Lecture Notes in Computer Science, vol. 3, Springer, Berlin, 1996, pp.208219.8 H. Dierks, PLC-Automata: a new class of implementable real-time automata, in: M. Bertran, T. Rus (Eds.), ARTS 97, Lecture Notes in Computer Science, Mallorca, Spain, vol. 1231, Springer, Berlin,May 1997, pp. 111125.9 H. Dierks, Synthesising controllers from real-time speci cations, in: 10th Internat. Symp. on SystemSynthesis, IEEE Computer Society, New York, September 1997, pp. 126133, short version of 11. 10 H. Dierks, Comparing model-checking and logical reasoning for real-time systems, in: Workshop Proc.of the ESSLLI 98, 1998, pp. 1322.11 H. Dierks, Synthesizing controllers from real-time speci cations, IEEE Transac. Comput.-Aided DesignIntegrated Circuits Systems 18 (1) (1999) 3343.12 H. Dierks, C. Dietz, Graphical speci cation and reasoning: Case study generalized railroad crossing, in: J. Fitzgerald, C.B. Jones, P. Lucas (Eds.), FME 97, Lecture Notes in Computer Science, vol. 1313,Graz, Austria, Springer, Berlin, September 1997, pp. 2039.13 H. Dierks, A. Fehnker, A. Mader, F.W. Vaandrager, Operational and logical semantics for polling real-time systems, in: Ravn, Rischel (Eds.), Formal Techniques in Real-Time and Fault-Tolerant Systems, Lecture Notes in Computer Science, vol. 1486, Lyngby, Denmark, Springer, Berlin, September1998. pp. 2940, short version of 14.14 H. Dierks, A. Fehnker, A. Mader, F.W. Vaandrager, Operational and logical semantics for polling real-time systems, Technical Report CSI-R9813, Computer Science Institue Nijmegen, Faculty ofMathematics and Informatics, Catholic University of Nijmegen, April 1998, full paper of 13.外文资料译文为柔性制造系统设计的可编程控制器平台摘要：在本文中，我们给出了基于PLC和以可视的个人PC机为基础的MMI和DAS单元的柔性制造系统（FMS）控制平台的设计和运行。FMS的关键方面是其在适应一个艰巨的进程运行时的灵活性。PLC 借助基于PC的MMI或DAS为FMS应用提供了可行的解决方法，其中PLC在执行高速的顺序控制策略时得到了优化。正运行着MMI / DAS的前端个人电脑提供了直观的操作界面，界面上有强大的图形和报告工具。个人电脑上的信息能发布在一个公司的局域网或用于客户技术服务的网络。目前，伴随着基本的微处理器技术和软件编程技术的融合，许多用户发现PLC提供了一个高效益的能在中小型加工厂实现实时控制的解决方案，特别是当与使用混合动力系统监督电脑结合时。这篇论文的主要任务是说明PLC是通过个人电脑的信息的自动化流通和接受运营商的指示来迅速响应和重复控制任务的，从而提供给用户了一个修改和监测过程作为要求改变的工具。关键字：PLC、柔性制造系统（FMS）、个人电脑。1.简介在各种各样的产品制造行业中，最自动的生产形式是20世纪70年代首先采用的柔性制造系统（FMS）。自从FMS能提供一个为提高批量生产力的高潜力，FMS的数量就大大增加了。这个遍及世界的加速度应归因于不断加剧的全球化竞争，缩短制造的循环时间和降低生产成本。一般地，以模块化子系统为形式的FMS是由一组机器或其他的自动化工作站组成的,例如数控机床、机器人、视觉系统和进程站。有通过材料处理系统互联的和由计算机驱动的（玛勒基，1991）。每个模块化系统都需要有一个特别的模块化控制系统，不同的元件由不同的控制单元控制。所有的模块化系统都像平常一样由计算机控制。这些控制单元在高水平控制器的监控下执行它们的任务。对于这个系统来说，控制装置和信息的流通都需要自动化。FMS的关键方面是它在控制任务时适应变化的能力。这个灵活性包括它能生产的类型的数量和种类，运行的顺序和重新往复流动的能力。最后，控制平台应该有使信息流动自动化的能力。通常情况下，有三种控制平台的类型用于FMS：小型机、微型机和PLC。小型机最适合复杂的、大规模的、连续的、监管的控制应用。PLC用于快速的和重复性的逻辑控制。个人电脑适用于操作员界面功能。主要地,PLC是用来代替硬接线继电器以运行在工业环境中。工厂工程师和维修人员很容易它们，而且，工厂电工很容易维修。目前，伴随着基本的微处理器技术和软件编程技术的融合，许多用户发现PLC提供了一个高效益的能在中小型加工厂实现实时控制的解决方案，特别是当与使用混合动力系统监督电脑结合时。这篇论文的意义在于解决FMS的先进技术.阐述了由PLC控制的、以PC机为基础的可视化人机接口以及DAS的设计和建设。具体组织如下。第2节的开始描述了在NJIT制造系统工厂车间中心的FMS.第3节给出了FMS的业务描述。第4、5节控制PLC的应用和以个人电脑为基础的MMI/DAS。第6节总结了控制PLC的应用和以个人电脑为基础的MMI/DAS的FMS的优点。2.FMS概述司处理输送系统它有四部分组成：A、B、C和D，每一部分都安装有固定装置，两个转换表TT1、TT2和为每个工作站运输材料的双传送带。图1. 灵活的制造系统NASA II数控铣床铣床接收长方形固体配件和依据电脑控制器的规定尺寸制成各种各样的元件。GE P50机器人 一个共用的机器人用来装卸数控铣床和输送系统之间的原料，还有部分机站和输送系统之间的原料。它包括五个由PLC承担的计算机编程。计算机程序指导机器人运输部分机站和小车、数控机床和小车之间的原料。后两个程序在接受或拒绝领域替换已完成的部分。图像机站部分这个机站有一个重力溜槽，这个重力溜槽提供固态坯作为原料。这个机站还有两本类型，分别是接受单元和拒绝单元。计算机可视系统这个可视系统为视觉自动检测提供帮助。它是一个菜单驱动器和边缘检测系统。钻床IBM7535工业化机器人是能钻出各种孔的自动化钻孔机。总地来说，FMS有两个机器人，一个是数控铣床即输送系统；另一个是可视系统。3.运行描述FMS进程的工作流程有以下步骤所示:1. 首先，输送系统上的四个小车是空的、可用的，从而来输送它上面的原料。2. GE机器人一个接一个的运输四部分到输送系统上的四个小车。轨道按顺时针输送。3. 一旦不同类型的四个部分被装载之后图表2就显示了这四个小车的位置。4. IBM机器人在铣床每个空白的部分钻各式各样的孔当作小车停止的地方。5. GE机器人移动到传送带，重新从小车所在的位置X1移动这一部分，并把它装载到数控机床表上的装置物。6. 一旦这一部分装载到数控机床上，机器人撤回并且铣床根据要求铣成矩形。7. 铣床运行后，机械手移动到铣床来重新移动按尺寸制造的那一部分。图2.装载后小车的位置8. 机器人把最后一部分放回到传送带上相同的小车上。9. 信号是被送到摄像头来检查这一部分的。10. 视觉系统分析这一部分并输出一个指导机器人来接受或拒绝这一部分的信号。11. 机器人既运行一个接受程序在接受区来代替这一部分或者运行一个拒绝程序在拒绝区来代替这一部分。12. GE机器人执行部分图像机站并在小车上装载新内容。13. 把小车放到系统中并进入到新一轮的循环中。4.PLC控制的FMSFMS控制系统的显著特点如下:1. 这个系统很容易配置、修改为容纳改变和更新。2. 类似地，这个系统很容易编程和用文件证明。3. 这个系统很容易保存，并且增强故障排除故障能力，因为在线诊断能用来查明故障并增强维修能力。4. 自然地，这个系统可以与计算机接口。PLC是一种通用工业控制计算机，它广泛应用在工业过程控制中。它有能力存储执行控制功能的指令，如测序、定时、计数、算术、数据处理和控制工业机器的通信和过程。PLC被选择来表现FMS的控制任务，这个任务基于以下特点:1) 高可靠性；2) 体积小、运行在工业环境中；3) 容易被工程师和技术员维修；4) 控制要求改变是能重新编程；5) 可以与其它计算机进行通信和联机。在应用程序里，GE-S7PLC装有存储库和I/O接口：8端口/模块的120VAC输入模块、8端口/模块的24VDC输入模块和8端口/模块的120VAC输出模块。5.以个人电脑为基础的可视操作界面单元随着微处理器与软件技术的融合，个人电脑已经在操作界面的应用中发挥了很大的作用。运行MMI/DAS前端的个人电脑很有用，可以很直观的操作应用，有很多有用的图形和制报告的工具。这些个人电脑上的信息可以通过局域网或客户服务技术网络传播。以PC机为基础的可视MMI/DAS用来监测过程和日志数据。MMI的作用是双重的。首先，在处理器和进程之间打开一个窗口后，在显示器上显示进程信息。它也允许处理器修改时间延迟常数或者当产品需要改变时不用改变梯形逻辑的报警设定。其次，它提供一个自动数据记录设备。它能创建批量、调换和每天的日志报告。PC机上的信息能通过局域网或客户服务技术网络传播。通过用现在一流的GENESIS为以PC机为基础的Windows软件编制应用程序，它从PLC通过RS232接口提供数据。这个途径允许PC机与控制器、编程终端、处理器接口和数据采集系统相结合在一个单元上。以PC机为基础的MMI/DAS软件提供了一个以图标为基础和鼠标驱动的开放式系统来设计一个实时控制策略和动态运行显示。随着结构特点的开放，它支持应用程序用户和局域网接口。MMI/DAS软件的其它部分是丰富的，并是友好的用户图形生成器。这个图形生成器是一个面向对象的以CAD为基础的工具。这个图像工具允许用户发出直观的、有用的人机界面屏幕来显示FMS的动态地位。 6.总结这个特定的FMS完全被一个混合控制平台控制。这个平台由PLC控制的基于PC 机的监控接口单元和数据数据采集系统组成。柔性制造的趋势需要更多的开放系统控制和能承受起的灵活性。显然，应用程序的大小和属性影响定案。PLC和PC机混合监督控制平台提供了一个具有成本效益的解决方案来实时控制和自动化。通过控制系统的可靠性、设备的维修、软件的可维护性和系统的灵活性来达到系统的改善。自动化的DAS系统有能力去发出批量的、轮流的来报告进程和设备报警，并刷新过程数据。专心-专注-专业