1、毕业设计（论文）英文翻译毕 业 设 计（论 文）译文Theoretical Computer Science 253 2009Developing a Hybrid Programmable Logic Controller Platform for a Flexible Manufacturing SystemHenning Dicrks University of Oldenburg Fachbereich Informatik P ostfach 2503 2900 Oldenburg. GermanyAbstract: In this article, we present the d
2、esign 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
3、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 to
4、ols. 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
5、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 a
6、ccept operator instructions, thereby providing the user a tool to modify and monitor the process as the requirements change.Key Words: PLC、FMS、PC.1IntroductionEarly in the last century seventys introduction of flexible manufacturing system ( FMS ) is the product of manufacturing industry in the prod
7、uction of the highest degree of automation. Since the flexible manufacturing system in the large scale production of highly efficient recognition, flexible manufacturing system are substantially growth ( Groover and Zimmers,1984). Manufacturing industry of global competition has led to the accelerat
8、ed development of flexible manufacturing system. Flexible manufacturing system reduces the manufacturing cycle and reduce the cost of production.In general, a flexible manufacturing system composed of a group of machines or other automated workstation, form a modular system, such as CNC machine tool
9、s, robots, visual system, and to a process station. These interrelated material handling systems are usually controlled by a computer drive ( Maleki,1991). Each modular system requires a separate modular control system, with individual unit controller for controlling the different components. All mo
10、dular subsystems as usual by computer control. The controller in than their more senior controller under the supervision of their respective operation work. In this system, both the control device or the flow of information must be automated. Flexible manufacturing system key function is able to ada
11、pt to changes in the ability to control task. This flexibility includes it can produce parts quantity and diversity, and the running order, it can put some changes in the procedure to the corresponding flow path. Finally, the control platform should have the ability to make the data process automati
12、on.Typically, there are three types of control platform for flexible manufacturing system: microcomputer, a micro processor and programmable logic controller ( Maleki,1991). The microcomputer is the most suitable for complex, large-scale, continuous, supervision control and other aspects of the appl
13、ication. The programmable logic controller is used for rapid and repeated logic control. Personal computer ( PC ) is suitable for the function of operation interface. Gradually, the development of PLCs will replace the relay, would create an industrial environment, more convenient plant engineers an
14、d repair personnel changes, and keep the plant electrician. Now, with the microprocessor technology and software programming technology convergence, many users find the PLCs for small - to medium-sized program machine real-time control has a cost effective solution, especially when using mixed and m
15、anagement system with personal computerGenerally, 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 driv
16、en 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 supervi
17、sion 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 prod
18、uce, 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, microcomputer
19、s, 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 replac
20、e 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 pr
21、ovide 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-controll
22、ed 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 t
23、he 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 sy
24、stemThis 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 a
25、nd 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
26、 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 incl
27、udes 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 gr
28、ay 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 l
29、imit 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
30、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 differe
31、nt 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
32、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. Th
33、e 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 pa
34、rt 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 featu
35、res 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 troublesh
36、ooting 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 ins
37、tructions 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 an
38、d 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 loade
39、d 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.The application of FMS as follows:Using this platform, you can use the network to store recorded audio, video, can als
40、o be shared data object, and these can be audio, video and a shared data object to a plurality of client, to achieve synchronous sharing. The platform integrates communication function and the function of the application program, it is through the Flash Player ( Flash player6 or higher ) in the clie
41、nt to provide audio sharing, video sharing and data flow.FMS is a purely based on software environment for multimedia real-time communication environment, representing the current real-time communication in the field of development direction, and also its own, blending a lot of new features, are use
42、d to create the next generation communications applications.In short, Adobe FMS is a multimedia application platform, on this platform, can realize the multimedia streaming VOD, streaming, interaction and other applications, because Adobe company in network multimedia application on strength, as wel
43、l as the Adobe Flash Player on the network wide application, therefore, FMS became a lot of multimedia application server end main application platform. Such as Youtube, Tudou etc.5. PC-based visual operator interface unitWith the convergence of microprocessor technology and software techniques, the
44、 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-serve
45、r 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 c
46、onstants 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 cli
47、ent-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 operato
48、r 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
49、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 opera
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