外文翻譯--關(guān)于plc的控制應(yīng)用

1、<p>　　PLC Control of the Application</p><p>　　1 Motivation</p><p>　　Programmable Logic Controllers (PLC), a computing device invented by Richard E. Morley in 1968, have been widely used in

2、industry including manufacturing systems, transportation systems, chemical process facilities, and many others. At that time, the PLC replaced the hardwired logic with soft-wired logic or so-called relay ladder logic (RL

3、L), a programming language visually resembling the hardwired logic, and reduced thereby the configuration time from 6 months down to 6 days.</p><p>　　Although PC based control has started to come into place,

4、 PLC based control will remain the technique to which the majority of industrial applications will adhere due to its higher performance, lower price, and superior reliability in harsh environments. Moreover, according to

5、 a study on the PLC market of Frost and Sullivan[1995], an increase of the annual sales volume to 15 million PLCs per year with the hardware value of more than 8 billion US dollars has been predicted, though the prices o

6、f c</p><p>　　Particularly, practical problems in PLC programming are to eliminate software bugs and to reduce the maintenance costs of old ladder logic programs. Though the hardware costs of PLCs are droppin

7、g continuously, reducing the scan time of the ladder logic is still an issue in industry so that low-cost PLCs can be used.</p><p>　　In general, the productivity in generating PLC is far behind compared to o

8、ther domains, for instance, VLSI design, where efficient computer aided design tools are in practice. Existent software engineering methodologies are not necessarily applicable to the PLC based software design because PL

9、C-programming requires a simultaneous consideration of hardware and software. The software design becomes, thereby, more and more the major cost driver. In many industrial design projects, more than SO0/a o</p>&l

10、t;p>　　In addition, current PLC based control systems are not properly designed to support the growing demand for flexibility and reconfigure ability of manufacturing systems. A further problem, impelling the need for

11、a systematic design methodology, is the increasing software complexity in large-scale projects.</p><p>　　1 Objective and Significance of the Thesis</p><p>　　The objective of this thesis is to de

12、velop a systematic software design methodology for PLC operated automation systems. The design methodology involves high-level description based on state transition models that treat automation control systems as discret

13、e event systems, a stepwise design process, and set of design rules providing guidance and measurements to achieve a successful design. The tangible outcome of this research is to find a way to reduce the uncertainty in

14、managing the control so</p><p>　　A systematic approach to designing PLC software can overcome deficiencies in the traditional way of programming manufacturing control systems, and can have wide ramifications

15、 in several industrial applications. Automation control systems are modeled by formal languages or, equivalently, by state machines. Formal representations provide a high-level description of the behavior of the system t

16、o be controlled. State machines can be analytically evaluated as to whether or not they meet the desired g</p><p>　　(1) Customer-Driven Manufacturing</p><p>　　In modern manufacturing, systems ar

17、e characterized by product and process innovation, become customer-driven and thus have to respond quickly to changing system requirements. A major challenge is therefore to provide enabling technologies that can economi

18、cally reconfigure automation control systems in response to changing needs and new opportunities. Design and operational knowledge can be reused in real-time, therefore, giving a significant competitive edge in industria

19、l practice.</p><p>　　(2) Higher Degree of Design Automation and Software Quality</p><p>　　Studies have shown that programming methodologies in automation systems have not been able to match rapi

20、d increase in use of computing resources. For instance, the programming of PLCs still relies on a conventional programming style with ladder logic diagrams. As a result, the delays and resources in programming are a majo

21、r stumbling stone for the progress of manufacturing industry. Testing and debugging may consume over 50% of the manpower allocated for the PLC program design. Standards [IEC 60</p><p>　　A systematic approach

22、 will increase the level of design automation through reusing existing software components, and will provide methods to make large-scale system design manageable. Likewise, it will improve software quality and reliabilit

23、y and will be relevant to systems high security standards, especially those having hazardous impact on the environment such as airport control, and public railroads.</p><p>　　(3) System Complexity</p>

24、<p>　　The software industry is regarded as a performance destructor and complexity generator. Steadily shrinking hardware prices spoils the need for software performance in terms of code optimization and efficiency

25、. The result is that massive and less efficient software code on one hand outpaces the gains in hardware performance on the other hand. Secondly, software proliferates into complexity of unmanageable dimensions; software

26、 redesign and maintenance-essential in modern automation systems-becomes</p><p>　　(4) Design Theory Development</p><p>　　Today, the primary focus of most design research is based on mechanical o

27、r electrical products. One of the by-products of this proposed research is to enhance our fundamental understanding of design theory and methodology by extending it to the field of engineering systems design. A system de

28、sign theory for large-scale and complex system is not yet fully developed. Particularly, the question of how to simplify a complicated or complex design task has not been tackled in a scientific way. Further</p>&

29、lt;p>　　(5) Application in Logical Hardware Design</p><p>　　From a logical perspective, PLC software design is similar to the hardware design of integrated circuits. Modern VLSI designs are extremely compl

30、ex with several million parts and a product development time of 3 years [Whitney, 1996]. The design process is normally separated into a component design and a system design stage. At component design stage, single funct

31、ions are designed and verified. At system design stage, components are aggregated and the whole system behavior and functionality is te</p><p>　　關(guān)于PLC的控制應(yīng)用</p><p><b>　　1 前言</b></p

32、><p>　　可編程序的邏輯控制器（PLC），是由Richard E. Morley 于1968年發(fā)明的，如今已經(jīng)被廣泛的應(yīng)用于生產(chǎn)、運(yùn)輸、化學(xué)等工業(yè)中。當(dāng)時(shí)的PLC以軟式—連線邏輯或所謂的繼電器梯形邏輯（RLL）代替HARDWIRED邏輯，程序的語(yǔ)言看起來(lái)像HARDWIRED邏輯，因此構(gòu)造時(shí)間從6個(gè)月降到了6天。</p><p>　　雖然現(xiàn)在的PC控制已經(jīng)開(kāi)始得到應(yīng)用，但由于PLC的高性能高

33、效率和低價(jià)位以及高可靠性，使它仍然廣泛應(yīng)用于大多數(shù)工業(yè)控制中。而且，根據(jù)在PLC市場(chǎng)或Richard E. Morley的一項(xiàng)研究[1995]，一個(gè)每年1500萬(wàn)件PLC硬件營(yíng)業(yè)額超過(guò)80億美元預(yù)言被證實(shí)。雖然計(jì)算機(jī)硬件的價(jià)格正穩(wěn)定地下降，但PLC的發(fā)明者，Richard E. Morley，認(rèn)為PLC市場(chǎng)是一個(gè)40億的行業(yè)。 尤其，在PLC程序設(shè)計(jì)過(guò)程中的實(shí)際問(wèn)題是消除軟件錯(cuò)誤并且降低舊的梯形邏輯程序的維修費(fèi)。雖然PLC的硬件

34、成本正在連續(xù)下降，降低梯形邏輯的掃描時(shí)間仍然是工業(yè)應(yīng)用中面臨的一個(gè)問(wèn)題，以便低成本的PLC能被使用。通常，在產(chǎn)生PLC過(guò)程中的生產(chǎn)力比其他領(lǐng)域低，例如，VLSI設(shè)計(jì)，有高效率的計(jì)算機(jī)輔助設(shè)計(jì)工具?，F(xiàn)有的軟件工程方法學(xué)對(duì)基于PLC的軟件設(shè)計(jì)不一定適用，因?yàn)镻LC語(yǔ)言需要同時(shí)考慮硬件和軟件。所以現(xiàn)在的軟件工程方法學(xué)對(duì)建立PLC的軟件設(shè)計(jì)不是必然可用的。在許多工業(yè)設(shè)計(jì)應(yīng)用中，超過(guò)50%的人力被預(yù)定為測(cè)試和檢查PLC程序錯(cuò)誤。 另外，

35、當(dāng)今的基于PLC的控制系統(tǒng)沒(méi)有被正確的用于支持日益增多的對(duì)制造</p><p><b>　　2 目標(biāo)和意義</b></p><p>　　這篇文章的目標(biāo)是PLC發(fā)展為一種系統(tǒng)的軟件設(shè)計(jì)方法學(xué)。設(shè)計(jì)方法學(xué)包括基于狀態(tài)轉(zhuǎn)移模型的高階層的描述，如離散系統(tǒng)，一個(gè)梯形程序的自動(dòng)化控制系統(tǒng)，而且提供指導(dǎo)達(dá)成一個(gè)成功的設(shè)計(jì)。這個(gè)課題的結(jié)果將尋找到在管理控制軟件開(kāi)發(fā)過(guò)程中的錯(cuò)誤，也就是

36、說(shuō)，減少經(jīng)過(guò)模組化程序和調(diào)試時(shí)間和他們的變化，增加自動(dòng)化系統(tǒng)的靈活性和促成軟件可復(fù)用性。目標(biāo)是克服單個(gè)軟件開(kāi)發(fā)者的經(jīng)驗(yàn)的現(xiàn)行程序規(guī)劃策略的缺點(diǎn)。</p><p>　　設(shè)計(jì)PLC軟件的有效方法能克服在生產(chǎn)控制系統(tǒng)的程序設(shè)計(jì)傳統(tǒng)的方式里的缺點(diǎn)，并且能夠在工業(yè)生產(chǎn)中有廣泛的應(yīng)用。自動(dòng)化控制系統(tǒng)被形式語(yǔ)言做模型，相等的狀態(tài)機(jī)可能被分析是否達(dá)到被要求的目標(biāo)。第二狀態(tài)機(jī)描述提供一個(gè)結(jié)構(gòu)化表示法傳達(dá)合乎邏輯的需求和約束，像是詳

37、細(xì)的安全定則。第三，明確的控制系統(tǒng)設(shè)計(jì)結(jié)果有助于自動(dòng)的代碼產(chǎn)生。生產(chǎn)可運(yùn)行的邏輯控制器上的控制軟件能降低軟件程序設(shè)計(jì)研制時(shí)間和人工成本。</p><p>　?。?）用戶驅(qū)動(dòng)的制造業(yè) </p><p>　　在現(xiàn)代生產(chǎn)過(guò)程中，系統(tǒng)以產(chǎn)品和生產(chǎn)流程革新為特點(diǎn)，因此必須對(duì)改變系統(tǒng)要求迅速反應(yīng)。主要的挑戰(zhàn)是提供技術(shù)以便在變更需要和新的機(jī)會(huì)之后節(jié)儉重新配置自動(dòng)化控制系統(tǒng)。設(shè)計(jì)和操作的知識(shí)可能被使

38、用，因此，在工業(yè)實(shí)踐過(guò)程中給予了重要的競(jìng)爭(zhēng)優(yōu)勢(shì)。</p><p>　?。?）設(shè)計(jì)的自動(dòng)化和軟件的高質(zhì)量</p><p>　　研究已經(jīng)顯示，在自動(dòng)化系統(tǒng)過(guò)程中的程序設(shè)計(jì)方法沒(méi)能與計(jì)算機(jī)資源的迅速增加相配合。例如，PLC的程序設(shè)計(jì)仍然是用梯形邏輯圖解依賴一種常規(guī)程序風(fēng)格。因此，延遲和資源是制造業(yè)發(fā)展的一塊主要的絆路石。測(cè)試和出錯(cuò)超過(guò)PLC程序設(shè)計(jì)被分派的50%的人力。標(biāo)準(zhǔn)[IEC60848，1

39、999；IEC611313，1993；IEC61499，1998；ISO15745-1，1999]已經(jīng)成為固定并且廣泛使用的最新型的設(shè)計(jì)方法，但是他們通常不能參加發(fā)展有效率的程序和系統(tǒng)的設(shè)計(jì)知識(shí)。</p><p>　　系統(tǒng)的方法將通過(guò)使用現(xiàn)有的新軟件增加設(shè)計(jì)自動(dòng)化的水平，并且提供方法使大規(guī)模系統(tǒng)設(shè)計(jì)容易。而且，它將會(huì)改良軟件質(zhì)量和可靠度，特別是危險(xiǎn)的環(huán)境，例如飛機(jī)場(chǎng)控制和鐵路。</p><p&

40、gt;<b>　?。?）系統(tǒng)的復(fù)雜性</b></p><p>　　軟件產(chǎn)業(yè)被認(rèn)為是一個(gè)績(jī)效析構(gòu)函數(shù)的產(chǎn)生器。硬件價(jià)格的下降損壞了軟件性能的需要和效率。結(jié)果是龐大的低效率軟件代碼在速度上超過(guò)了硬件的性能。第二，軟件到了難以控制大小的復(fù)雜性；軟件重新設(shè)計(jì)和維護(hù)在現(xiàn)代化的自動(dòng)化系統(tǒng)中幾乎變得不可能。特別地，PLC程序已經(jīng)在25年以前從一個(gè)電耦程序編碼行進(jìn)展到有輸入/輸出點(diǎn)的一個(gè)相似的數(shù)以千計(jì)的編碼

41、行。例如在增加安全放火墻上，現(xiàn)代自動(dòng)化系統(tǒng)的靈活性給予復(fù)雜性計(jì)劃設(shè)計(jì)過(guò)程。從而，軟件的生命周期費(fèi)用是永久增長(zhǎng)總費(fèi)用的一小部分。這些費(fèi)用的80%～90%作為軟件的維護(hù)，調(diào)整，適應(yīng)和擴(kuò)大滿足不斷變化的需求。</p><p><b>　　（4）設(shè)計(jì)理論發(fā)展</b></p><p>　　如今，大多數(shù)的設(shè)計(jì)研究的主要焦點(diǎn)以機(jī)械或電氣產(chǎn)品為基礎(chǔ)。被計(jì)劃研究的副產(chǎn)品之一將提高我們對(duì)

42、基本設(shè)計(jì)理論和方法學(xué)的理解，通過(guò)把它擴(kuò)大到工程系統(tǒng)設(shè)計(jì)的領(lǐng)域。大規(guī)模和復(fù)雜系統(tǒng)的設(shè)計(jì)理論還沒(méi)被完全發(fā)展。尤其，怎樣簡(jiǎn)化一項(xiàng)錯(cuò)綜復(fù)雜或者復(fù)雜的設(shè)計(jì)工作的問(wèn)題還沒(méi)被以科學(xué)方式處理。而且，在設(shè)計(jì)理論和最新epistemological正式表現(xiàn)在計(jì)算機(jī)科學(xué)和運(yùn)籌學(xué)的結(jié)果之間，例如模型化系統(tǒng)分離事件，將推動(dòng)以后的工程設(shè)計(jì)。</p><p>　?。?）在合乎邏輯的硬件設(shè)計(jì)過(guò)程中的應(yīng)用</p><p>