實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)【含CAD圖紙、說明書】
實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)【含CAD圖紙、說明書】,含CAD圖紙、說明書,實(shí)驗(yàn),試驗(yàn),軌道,小車,運(yùn)動,控制系統(tǒng),設(shè)計(jì),cad,圖紙,說明書,仿單
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畢業(yè)設(shè)計(jì)(論文)開題報(bào)告
學(xué)生姓名: 學(xué) 號:
學(xué) 院: 機(jī)電工程學(xué)院
專業(yè)年級: 10級機(jī)械設(shè)計(jì)制造及其自動化班
題 目: 實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)
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1.結(jié)合畢業(yè)設(shè)計(jì)(論文)課題情況,根據(jù)所查閱的文獻(xiàn)資料,每人撰寫
1500字左右的文獻(xiàn)綜述(包括研究進(jìn)展,選題依據(jù)、目的、意義)
文 獻(xiàn) 綜 述
1、研究進(jìn)展
早期試驗(yàn)軌道小車電氣控制系統(tǒng)多為繼電器—接觸器組成的復(fù)雜系統(tǒng),這種系統(tǒng)存在設(shè)計(jì)周期長、體積大、成本高等缺陷,無數(shù)據(jù)處理和通信功能,必須有專人負(fù)責(zé)操作,將PLC應(yīng)用[1]到軌道小車電氣控制系統(tǒng),可實(shí)現(xiàn)軌道小車的自動化控制,降低系統(tǒng)的運(yùn)行費(fèi)用,PLC軌道小車電氣控制系統(tǒng)具有連線簡單,控制速度快,可靠性和可維護(hù)性好,易于安裝、維修和改造等優(yōu)點(diǎn)。隨著經(jīng)濟(jì)的發(fā)展,軌道小車不斷擴(kuò)大到各個(gè)領(lǐng)域,從手動到自動,逐漸形成了機(jī)械化、自動化。??
目前,軌道小車的控制系統(tǒng)的發(fā)展?fàn)顩r,最早被應(yīng)用的技術(shù)是基于單片機(jī)的控制系統(tǒng)。在單片機(jī)的基礎(chǔ)上,通過研發(fā)實(shí)現(xiàn)了一種以光電傳感器為敏感原件以AT89C51單片機(jī)為控制核心的電動循軌小車的智能控制系統(tǒng);在基于單片機(jī)的基礎(chǔ)上,使小車的電動機(jī)采用PID算法閉環(huán)調(diào)速,形成了對小車調(diào)速的另一種控制系統(tǒng)。隨著智能控制的不斷發(fā)展,繼而又有人提出了模糊PID控制算法[2],是控制系統(tǒng)的性能又有了進(jìn)一步的提升;當(dāng)然,還有在工業(yè)中被普遍應(yīng)用的PLC控制系統(tǒng)。
針對控制系統(tǒng),PLC系統(tǒng)在工業(yè)控制中有著非常中重要的作用,由于PLC的功能非常強(qiáng)大,能夠抵抗較強(qiáng)的干擾,可靠性比較高,同時(shí)編程簡單,操作方便,因此在工業(yè)控制中的應(yīng)用越來越廣泛。目前,隨著科技的不斷進(jìn)步,自動控制系統(tǒng)技術(shù)已經(jīng)越來越多的唄應(yīng)用于各種行業(yè)當(dāng)中,西門子控制電機(jī),基于PLC系統(tǒng)的電機(jī)自動控制采用國際標(biāo)準(zhǔn)PROFIBUS現(xiàn)場總線標(biāo)準(zhǔn)[3],保證了系統(tǒng)的高效性與實(shí)時(shí)性,不但能夠?qū)崿F(xiàn)對設(shè)備數(shù)據(jù)采集的獨(dú)立完成,同時(shí)其抗干擾性的能力比較強(qiáng),可靠性高,具有非常高的控制精度。
將PLC應(yīng)用到軌道小車電氣控制系統(tǒng)[4],可實(shí)現(xiàn)軌道小車的自動化控制,降低系統(tǒng)的運(yùn)行費(fèi)用。它功能強(qiáng)大,可擴(kuò)展到多達(dá)128I/O點(diǎn),且能增加特殊功能模塊或擴(kuò)展板。通信和數(shù)據(jù)連接功能選項(xiàng)使得FX1N在體積、通信和特殊功能模塊等重要的應(yīng)用方面非常完美。本課題主要包括:分析被控對象和明確系統(tǒng)控制要求;PLC選型;確定系統(tǒng)的I/O[5]設(shè)備的數(shù)量及種類;控制流程設(shè)計(jì);控制程序設(shè)計(jì)。?PLC在軌道小車控制系統(tǒng)中的應(yīng)用,已經(jīng)在國內(nèi)外工程[6]、工廠中得到實(shí)際應(yīng)用,具有巨大的經(jīng)濟(jì)和社會價(jià)值,其智能化和自動化的思路值得以后繼續(xù)深入研究和推廣。
實(shí)驗(yàn)軌道小車可以認(rèn)為是半自動控制[7]小車的一種,而自能控制小車將是未來的總體趨勢。目前市場上有應(yīng)用于物流的運(yùn)料只能控制小車,傳統(tǒng)的運(yùn)料小車大都是繼電器控制,而繼電器控制有著接線繁多,故障率高的缺點(diǎn),且維護(hù)維修不易等缺點(diǎn)。作為目前國內(nèi)控制市場上的主流控制器[8],plc在市場、技術(shù)、行業(yè)影響等方面有重要作用,利用PLC控制來代替繼電器控制已是大勢所趨。?
在國際上PLC迅速發(fā)展的形勢下,我國多數(shù)PLC廠家還沒有擁有自主知識產(chǎn)權(quán),能夠參與國際競爭的PLC產(chǎn)品?,其中之一就是研發(fā)實(shí)力不夠。雖然資金投入、生產(chǎn)和質(zhì)量管理等因素也占有非常大的比重,但對產(chǎn)品的質(zhì)量起著決定性作用的是研發(fā)投入、研發(fā)成果產(chǎn)品化以及生產(chǎn)工藝等。而技術(shù)則是貫穿著其中每一個(gè)環(huán)節(jié),PLC核心技術(shù)的開發(fā)、產(chǎn)品的后續(xù)開發(fā)、生產(chǎn)工藝的技術(shù)水平是決定產(chǎn)品質(zhì)量的前提,如何在技術(shù)上進(jìn)一步增強(qiáng)自己的實(shí)力,將是國產(chǎn)品牌取得市場競爭優(yōu)勢的關(guān)鍵。?
依據(jù)得到的樣本分析,初步得出正在使用的眾多PLC的品牌中?,西門子、三菱及omron[9]占據(jù)絕對的優(yōu)勢,60%左右的用戶使用了這些品牌的PLC產(chǎn)品,而rockwell/ab[10]、ge-fanuc[11]和富士等品牌也占有相當(dāng)?shù)氖袌龇蓊~。
我國可編程控制器的引進(jìn)、應(yīng)用、研制、生產(chǎn)是伴隨著改革開放開始的。最初是在引進(jìn)設(shè)備中大量使用了可編程控制器。接下來在各種企業(yè)的生產(chǎn)設(shè)備及產(chǎn)品中不斷擴(kuò)大了PLC的應(yīng)用。目前,我國自己已可以生產(chǎn)中小型可編程控制器。上海東屋電氣有限公司生產(chǎn)的CF系列、杭州機(jī)床電器廠生產(chǎn)的DKK及D系列、大連組合機(jī)床研究所生產(chǎn)的S系列、蘇州電子計(jì)算機(jī)廠生產(chǎn)的YZ系列等多種產(chǎn)品已具備了一定的規(guī)模并在工業(yè)產(chǎn)品中獲得了應(yīng)用。此外,無錫華光公司、上海鄉(xiāng)島公司等中外合資企業(yè)也是我國比較著名的PLC生產(chǎn)廠家??梢灶A(yù)期,隨著我國現(xiàn)代化進(jìn)程的深入,PLC在我國將有更廣闊的應(yīng)用天地。
2.選題依據(jù)
雖然目前軌道小車很多,但是具有局限性,針對不同的用途和環(huán)境等都有著較大的影響。本次選題是針對國家高速列車實(shí)驗(yàn)室試驗(yàn)用途針對性設(shè)計(jì)的實(shí)驗(yàn)軌道小車控制系統(tǒng)設(shè)計(jì)?;赑LC的控制系統(tǒng)能夠精確的控制軌道小車的運(yùn)行速度和運(yùn)行距離,并且操作簡單,運(yùn)行平穩(wěn),安全性較好,能夠滿足軌道小車裝載精密儀器在實(shí)驗(yàn)室條件下的各項(xiàng)具體參數(shù)要求。
3.選題目的
通過參考其他比較好的控制系統(tǒng),基于PLC的試驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)能夠滿足國家高速列車實(shí)驗(yàn)室試驗(yàn)用途,提高測試條件下小車的運(yùn)行平穩(wěn)精度,為測試條件下測試所得數(shù)據(jù)更加可靠和簡便,改善試驗(yàn)條件下參數(shù)的可靠性和準(zhǔn)確性。
4.選題意義
PLC運(yùn)動控制系統(tǒng)廣泛應(yīng)用于工業(yè)控制領(lǐng)域。雖然試驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)還只是滿足實(shí)驗(yàn)室用,但基于PLC的控制系統(tǒng)會被運(yùn)用在各個(gè)行業(yè),同時(shí),PLC的功能也不斷完善。隨著計(jì)算機(jī)技術(shù)、信號處理技術(shù)、控制技術(shù)網(wǎng)絡(luò)技術(shù)的不斷發(fā)展和用戶需求的不斷提高,PLC在開關(guān)量處理的基礎(chǔ)上增加了模擬量處理和運(yùn)動控制等功能。今天的PLC不再局限于邏輯控制,在運(yùn)動控制、過程控制等領(lǐng)域也發(fā)揮著十分重要的作用。
參考文獻(xiàn)
[1]?汪志峰.PLC控制器原理及應(yīng)用[M].北京?電子工業(yè)出版社??2007。
[2]?楊東,?黃永紅,?張新華,?吉敬華.?用PLC基本指令實(shí)現(xiàn)自動運(yùn)動定位控制的
研究[J].?微計(jì)算機(jī)信息,?2010,?26(2-1):?62-64.
[3]?徐世許.可編程控制器原理應(yīng)用網(wǎng)絡(luò)?[M].長沙:中國科學(xué)技術(shù)大學(xué)出版社,2000。?
[4]?W.Bolton.Programmable Logic Controllers and?Control System [M].Journal of computer?and structure?2007。?
[5]?張強(qiáng),?文懷興,?陳嬋娟.?數(shù)字量I/O卡在快速成型機(jī)多軸控制中的應(yīng)用[J].?
控制與檢測,?2008,?4(64):?64-70.?
[6]?薛開,?王平,?王文斌.?基于多軸運(yùn)動控制器的二軸轉(zhuǎn)臺控制系統(tǒng)[J].?哈爾
濱工程大學(xué)學(xué)報(bào),?2006,?27(4):?570-573.?
[7]?劉建峰.?基于PAC的多軸運(yùn)動控制系統(tǒng)的研究[J].?機(jī)械制造與自動化,?
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[8]?朱華征,?范大鵬,?龐新良.?基于可編程多軸控制器的三軸轉(zhuǎn)臺控制系統(tǒng)[J].?
兵工自動化,?2004,?23(01):?55-57.?
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programming?manual?[EB/OL].?(2004-10-05)[2008-09-10].?
[10]?秦琴,?王忠慶.?利用PLC的高速計(jì)數(shù)功能實(shí)現(xiàn)軸的精確定位控制.?電氣技術(shù).??
2009(3).?
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shanghai?university.?Vol.1.No.1.1997.?
[12]?Ren?Sheng-le.?Development?of?PLC-based?Tension?Control?System.?
Chinese?Journal?of?Aeronautics20?(2007)?266-271.?
[13]?松下PLC(中國)FP系列用戶手冊.2010?
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[15]?魏大忠,?徐健,?吳任東等.?基于MCT運(yùn)動控制器的快速成型機(jī)數(shù)控系統(tǒng)研究
[J].組合機(jī)床與自動化加工技術(shù),?2003(4).??
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2.本課題要研究或解決的問題和擬采用的研究手段(途徑):
實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)是基于松下PLC的閉環(huán)控制系統(tǒng)設(shè)計(jì)。采用松下PLC邏輯控制器實(shí)現(xiàn)對實(shí)驗(yàn)軌道小車運(yùn)動速度V、運(yùn)行距離S檢測并反饋的全閉環(huán)控制。松下PLC控制器已經(jīng)使用比較成熟,采用Mewtocol通訊協(xié)議且穩(wěn)定性和安全性可靠,經(jīng)濟(jì)性好,可以選為控制系統(tǒng)的硬件設(shè)備。該控制系統(tǒng)可以有效地解決控制復(fù)雜、操作不便,控制輸出不穩(wěn)定、控制精度不高等控制系統(tǒng)問題。
本控制系統(tǒng)可以大概分為五個(gè)部分:PLC邏輯控制器部分、直流無刷電機(jī)控制器部分、編碼器檢測反饋部分、觸摸屏人機(jī)交互界面部分、外部硬件控制部分。
⑴PLC邏輯控制器部分:實(shí)時(shí)接收和處理從編碼器、外部觸發(fā)硬件傳送過來的信號,內(nèi)部計(jì)算處理數(shù)據(jù)形成相應(yīng)的參數(shù)分別輸送至①模擬量插件:形成相對應(yīng)的控制電壓,再將控制電壓輸送至直流無刷電機(jī)控制器調(diào)控電機(jī)轉(zhuǎn)速n;②直流無刷控制器:前進(jìn)、后退和制動數(shù)據(jù)信號。
⑵直流無刷控制器部分:接收模擬量插件和PLC傳輸過來的信號,控制電機(jī)的轉(zhuǎn)速n、前進(jìn)、后退和制動,即控制實(shí)驗(yàn)軌道小車的運(yùn)行速度V、前進(jìn)、后退和制動。
⑶編碼器檢測反饋部分:實(shí)時(shí)檢測實(shí)驗(yàn)軌道小車的運(yùn)行速度V和運(yùn)行距離S并將數(shù)據(jù)反饋至PLC邏輯控制器。
⑷觸摸屏人機(jī)交互界面部分:參數(shù)設(shè)置小車運(yùn)行速度V和運(yùn)行距離S參數(shù),軟件按鈕控制實(shí)驗(yàn)軌道小車的前進(jìn)、后退和制動,并實(shí)時(shí)顯示小車的運(yùn)行速度V和運(yùn)行距離S。
⑸外部硬件控制部分:包括前進(jìn)、后退中的行程開關(guān)和緊急制動按鈕。
通過人機(jī)交互界面觸摸屏設(shè)定運(yùn)行速度V和運(yùn)行距離S并以最大且恒定的加速度加速啟動,編碼器開始不斷的檢測反饋,比較是否達(dá)到了設(shè)定運(yùn)行速度和運(yùn)行距離,若沒有達(dá)到時(shí)則繼續(xù)以加速,當(dāng)達(dá)到時(shí)則保持運(yùn)行速度運(yùn)行直至達(dá)到指定運(yùn)行距離制動停止。該運(yùn)行過程中觸摸屏可實(shí)時(shí)顯示運(yùn)行速度V和運(yùn)行距離S,運(yùn)行遇危險(xiǎn)時(shí)刻可按下硬件的緊急制動按鈕,同時(shí)軌道兩端安裝了行程開關(guān),小車不能在指定地點(diǎn)制動而觸碰到行程開關(guān)時(shí),行程開關(guān)被觸發(fā)發(fā)出制動信號,直流無刷控制器控制小車制動停止。
閉環(huán)反饋控制系統(tǒng)通過比較系統(tǒng)行為(輸出)與期望行為之間的偏差,并消除偏差以獲得預(yù)期的系統(tǒng)性能,有效的避免了由于設(shè)備、環(huán)境等外部因素影響產(chǎn)生的誤差,并且能夠較穩(wěn)定的輸出和較精確的達(dá)到技術(shù)要求。
1、 控制系統(tǒng)原理方框圖 :
GT01
觸摸屏
直流無刷
控制器
行程開關(guān)
旋轉(zhuǎn)編碼器
電機(jī)(實(shí)驗(yàn)軌道小車)
P L C
緊急制動按鈕
2、控制流程圖
指導(dǎo)教師意見:
1.對“文獻(xiàn)綜述”的評語:
2.對本課題的深度、廣度及工作量的意見和對設(shè)計(jì)(論文)結(jié)果的預(yù)測:
指導(dǎo)教師:
年 月 日
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負(fù)責(zé)人:
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畢業(yè)設(shè)計(jì)(論文)實(shí)習(xí)報(bào)告
學(xué)生姓名:
學(xué) 院: 機(jī)電工程學(xué)院
專業(yè)年級:
題 目: 實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)
實(shí)習(xí)地點(diǎn):
實(shí)習(xí)時(shí)間:
指導(dǎo)教師:
日 期:
實(shí)習(xí)目的:
通過公司的實(shí)習(xí),了解和掌握了機(jī)械設(shè)計(jì)、工藝設(shè)計(jì)和流程、控制系統(tǒng)的實(shí)踐。培養(yǎng)我們理論聯(lián)系實(shí)際的能力。提高實(shí)踐能力、動手能力、觀察問題、分析問題、解決問題的能力。為以后的工作打下了堅(jiān)實(shí)的基礎(chǔ)。
實(shí)習(xí)單位:
長沙銳諾機(jī)電科技有限公司
實(shí)習(xí)內(nèi)容和心得體會:
自從去年12月份以來在長沙銳諾機(jī)電科技有限公司做實(shí)驗(yàn)軌道小車的項(xiàng)目,實(shí)驗(yàn)軌道小車是為中南大學(xué)國家高速列車實(shí)驗(yàn)室實(shí)驗(yàn)用設(shè)計(jì)的。從最初的機(jī)械部分方案設(shè)計(jì)到小車實(shí)物的做好,控制部分系統(tǒng)的設(shè)計(jì)到調(diào)試完成,4個(gè)月的實(shí)習(xí)經(jīng)歷讓我學(xué)到了很多。可以說是大學(xué)所學(xué)知識的一個(gè)回顧和實(shí)踐,新知識學(xué)習(xí)的開始!
13年12月份開始著手機(jī)械部分的設(shè)計(jì),經(jīng)過和龔教授、同學(xué)還有長沙銳諾機(jī)電科技有限公司楊總的討論確定了機(jī)械部分為四輪驅(qū)動,機(jī)械部分雖然是劉同學(xué)主要負(fù)責(zé),但是我也積極參與設(shè)計(jì)畫圖,回顧了二維軟件Auotcad和三維軟件Proe的操作使用。最初我們根據(jù)方案和參數(shù)要求通過理論的計(jì)算選擇好動力源部分,即選擇的是直流無刷電機(jī),再根據(jù)電機(jī)從上而下逐步確定好減速機(jī)構(gòu)、傳動機(jī)構(gòu)、執(zhí)行機(jī)構(gòu)等。在設(shè)計(jì)的同時(shí)也有一部分零件和部件是外購的,但是也經(jīng)過我們部分的設(shè)計(jì)改動來符合我們的設(shè)計(jì)方案要求,這個(gè)過程中就有F系列的減速器、T型換向器。這個(gè)過程我們不僅學(xué)會了選擇設(shè)備的型號,在改動的同時(shí)學(xué)會了我們自己改動的設(shè)計(jì)方案要符合工藝加工過程。軌道小車的車輪和承載板等完全由我們自己設(shè)計(jì),并且加工時(shí)我們還特別到了工廠里面了解工藝過程,對機(jī)械零件的加工工藝過程有了深一步的了解和認(rèn)識。在承載板加工過程中我還親自體驗(yàn)的螺紋孔的攻絲等。
14年2月到3月所有基本零件和部件都做好了,我們到工廠里面指導(dǎo)工人的安裝。廠里面的師傅在安裝過程中遇到了配合不好的問題,并及時(shí)跟我們交流,我們深刻認(rèn)識到設(shè)計(jì)和實(shí)際情況還是有很大差別的,因?yàn)槭艿街T多比如加工誤差、制造誤差、測量誤差和安裝誤差等因素的影響。因此在今后的設(shè)計(jì)過程中要學(xué)會解決實(shí)際問題。
從機(jī)械部分的開始,我就逐步著手設(shè)計(jì)控制系統(tǒng)部分。之前接觸過三菱FN2X控制的一點(diǎn)知識,但是沒有完全掌握,所以花了很長一段時(shí)間去學(xué)習(xí)。但是后來公司里面都是用的松下PLC,所以自己又花了一個(gè)多禮拜把松下PLC的學(xué)習(xí)和了解。從松下編程軟件FPWIN GR 2和觸摸屏編程軟件GTWIN的學(xué)習(xí),一邊看編程手冊和用戶使用手冊,一邊查資料解決遇到編程時(shí)遇到的實(shí)際問題。根據(jù)自己編號的控制系統(tǒng)流程圖逐步編自己控制系統(tǒng)的程序。2月份直流無刷電機(jī)、蓄電和控制開關(guān)買回來了,自己試著學(xué)會簡單的接線。然后在實(shí)驗(yàn)室用簡單的PLC程序控制電機(jī)的正轉(zhuǎn)、反轉(zhuǎn)和制動,緊接著學(xué)會使用PLC的DA2模擬量模塊。這個(gè)模塊就是把數(shù)字量轉(zhuǎn)化成電流、電壓等基本的模擬連續(xù)量輸出。在用PLC模擬量模塊實(shí)驗(yàn)電機(jī)調(diào)速的過程中,做了三次實(shí)驗(yàn),然后利用Matlab做了數(shù)據(jù)處理的仿真,發(fā)現(xiàn)電機(jī)并不是完全符合說明書上的參數(shù),發(fā)生了轉(zhuǎn)速的損失等。這再一次說明了控制系統(tǒng)設(shè)計(jì)過程中存在的影響因素。這時(shí)我根據(jù)存在的問題從新設(shè)計(jì)了控制部分的控制方案,并且得到了了陳飛老師,龔教授的指導(dǎo),再根據(jù)實(shí)驗(yàn)情況下編碼器反饋的情況逐步調(diào)整方案設(shè)計(jì)。
一開始接觸旋轉(zhuǎn)編碼器不是很懂,自己也開了說明書,但是還是沒學(xué)會編碼器的接線。我直接去請教公司的譚工程師,但是他沒有直接告訴我,而是叫我自己再仔細(xì)看看《用戶使用手冊》,經(jīng)過譚工程師的指導(dǎo),我終于學(xué)會了。自己一步步腳踏實(shí)地學(xué)習(xí)學(xué)到的知識還是比不花費(fèi)時(shí)間和經(jīng)歷學(xué)來的知識要深刻。
3月份到廠里具體的調(diào)試前,接線的時(shí)候不是很有效率,也不是很會。當(dāng)時(shí)公司的楊總就親自給我們接線,看著他做事的態(tài)度讓我感到工科人做事一點(diǎn)也不能馬虎。
4月份實(shí)驗(yàn)軌道小車是為中南大學(xué)國家高速列車實(shí)驗(yàn)室實(shí)驗(yàn)用設(shè)計(jì)的,應(yīng)實(shí)驗(yàn)室軌道應(yīng)該很快做好了,我們項(xiàng)目最后的調(diào)試部分也很快會展開。
經(jīng)過這次項(xiàng)目的經(jīng)歷,讓我不僅回顧了舊知識,認(rèn)識到自己學(xué)到的知識還不夠牢固,有待加強(qiáng)知識的實(shí)踐;同時(shí)也學(xué)習(xí)到了很多新的知識,開拓了我的視野。認(rèn)識到我們機(jī)械專業(yè)素質(zhì)是非常嚴(yán)謹(jǐn)?shù)?,不斷的加?qiáng)我們的專業(yè)素質(zhì),更好的勝任我們的工作!感謝做項(xiàng)目過程中給與我?guī)椭睦蠋?、同學(xué)還有長沙銳諾機(jī)電科技有限公司。
3
本科畢業(yè)設(shè)計(jì)外文翻譯
外文譯文題目(中文)可編程邏輯控制器及其控制系統(tǒng)
學(xué)生姓名
學(xué) 院
專業(yè)年級
題 目: 實(shí)驗(yàn)軌道小車運(yùn)動控制系統(tǒng)設(shè)計(jì)
指導(dǎo)教師:
日 期: 年4月1日
Programmable Logic Controllers and?Control System W. Bolton
Received 28 April 2004; received in revised form 3 November 2004; accepted 29 Novembe 2004;
Available online 29 January 2005
Abstract
Early electric control system of the transporter over the relay-contactor complex system composed of The system design cycle,there is a long,bulky,high cost,defects,no data processing and communications functions, must be hand operated.PLC control system for electric transport-
er with a simple connection to control speed, reliability and maintainability is good,easy to insta-
ll,repair and improvement and so on.With economic development,growing transporter from
manual to automatic,and gradually formed the mechanization and automation.
PLC applied to electrical control system and can realize automatic control operation and
reduce system operating costs.Communications and data connectivity options make FX1N in volume,communications and special function modules such important applications perfectly.The topics include:analysis of plant and a clear system control requirements; PLC selection; determine the system's I / O device number and type; control process design; control programming.
Key words:PLC,control system,I/O points
1 。About Programmable Logic Controllers (PLCs)
PLCs (programmable logic controllers) are the control hubs for a wide variety of automated systems and processes. They contain multiple inputs and outputs that use transistors and other circuitry to simulate switches and relays to control equipment. They are programmable via software interfaced via standard computer interfaces and proprietary languages and network options.
Programmable logic controllers I/O channel specifications include total number of points, number of inputs and outputs, ability to expand, and maximum number of channels.? Number of points is the sum of the inputs and the outputs. PLCs may be specified by any possible combination of these values.? Expandable units may be stacked or linked together to increase total control capacity.? Maximum number of channels refers to the maximum total number of input and output channels in an expanded system.? PLC system specifications to consider include scan time, number of instructions, data memory, and program memory.? Scan time is the time required by the PLC to check the states of its inputs and outputs.? Instructions are standard operations (such as math functions) available to PLC software.? Data memory is the capacity for data storage.? Program memory is the capacity for control software.
Available inputs for programmable logic controllers include DC, AC, analog, thermocouple, RTD, frequency or pulse, transistor, and interrupt inputs.? Outputs for PLCs include DC, AC, relay, analog, frequency or pulse, transistor, and triac.? Programming options for PLCs include front panel, hand held, and computer.
Programmable logic controllers use a variety of software programming languages for control.? These include IEC 61131-3, sequential function chart (SFC), function block diagram (FBD), ladder diagram (LD), structured text (ST), instruction list (IL), relay ladder logic (RLL), flow chart, C, and Basic.? The IEC 61131-3 programming environment provides support for five languages specified by the global standard: Sequential Function Chart, Function Block Diagram, Ladder Diagram, Structured Text, and Instruction List. This allows for multi-vendor compatibility and multi-language programming.? SFC is a graphical language that provides coordination of program sequences, supporting alternative sequence selections and parallel sequences.? FBD uses a broad function library to build complex procedures in a graphical format. Standard math and logic functions may be coordinated with customizable communication and interface functions.? LD is a graphic language for discrete control and interlocking logic. It is completely compatible with FBD for discrete function control.? ST is a text language used for complex mathematical procedures and calculations less well suited to graphical languages.? IL is a low-level language similar to assembly
code. It is used in relatively simple logic instructions.? Relay Ladder Logic (RLL), or ladder diagrams, is the primary programming language for programmable logic controllers (PLCs). Ladder logic programming is a graphical representation of the program designed to look like relay logic.? Flow Chart is a graphical language that describes sequential operations in a controller sequence or application. It is used to build modular, reusable function libraries.? C is a high level programming language suited to handle the most complex computation, sequential, and data logging tasks. It is typically developed and debugged on a PC.? BASIC is a high level language used to handle mathematical, sequential, data capturing and interface functions.
Programmable logic controllers can also be specified with a number of computer interface options, network specifications and features.? PLC power options, mounting options and environmental operating conditions are all also important to consider.
2 。INTRODUCTION
For simple programming the relay model of the PLC is sufficient. As more complex functions are used the more complex VonNeuman model of the PLC must be used. A VonNeuman computer processes one instruction at a time. Most computers operate this way, although they appear to be doing many things at once. Consider the computer components shown in Figure 1.
Figure 1 1 Simplified Personal Computer Architecture
Input is obtained from the keyboard and mouse, output is sent to the screen, and the disk and memory are used for both input and output for storage. (Note: the directions of these arrows are very important to engineers, always pay attention to indicate where information is flowing.) This figure can be redrawn as in Figure 2 to clarify the role of inputs and outputs.
Figure 2 An Input-Output Oriented Architecture
In this figure the data enters the left side through the inputs. (Note: most engineering diagrams have inputs on the left and outputs on the right.) It travels through buffering circuits before it enters the CPU. The CPU outputs data through other circuits. Memory and disks are used for storage of data that is not destined for output. If we look at a personal computer as a controller, it is controlling the user by outputting stimuli on the screen, and inputting responses from the mouse and the keyboard.
A PLC is also a computer controlling a process. When fully integrated into an application the analogies become;
inputs - the keyboard is analogous to a proximity switch
input -circuits - the serial input chip is like a 24Vdc input card
computer - the 686 CPU is like a PLC CPU unit
output - circuits - a graphics card is like a triac output card
outputs - a monitor is like a light
storage - memory in PLCs is similar to memories in personal computers
It is also possible to implement a PLC using a normal Personal Computer, although this is not advisable. In the case of a PLC the inputs and outputs are designed to be more reliable and rugged for harsh production environments.
3 。 OPERATION SEQUENCE
All PLCs have four basic stages of operations that are repeated many times per second. Initially when turned on the first time it will check it’s own hardware and software for faults. If there are no problems it will copy all the input and copy their values into memory, this is called the input scan. Using only the memory copy of the inputs the ladder logic program will be solved once, this is called the logic scan. While solving the ladder logic the output values are only changed in temporary memory. When the ladder scan is done the outputs will be updated using the temporary values in memory, this is called the output scan. The PLC now restarts the process by starting a self check for faults. This process typically repeats 10 to 100 times per second as is shown in Figure 3.
Figure 3 PLC Scan Cycle
SELF TEST - Checks to see if all cards error free, reset watch-dog timer, etc. (A watchdog timer will cause an error, and shut down the PLC if not reset within a short period of time - this would indicate that the ladder logic is not being scanned normally).
INPUT SCAN - Reads input values from the chips in the input cards, and copies their values to memory. This makes the PLC operation faster, and avoids cases where an input changes from the start to the end of the program (e.g., an emergency stop). There are special PLC functions that read the inputs directly, and avoid the input tables.
LOGIC SOLVE/SCAN - Based on the input table in memory, the program is executed 1 step at a time, and outputs are updated. This is the focus of the later sections.
OUTPUT SCAN - The output table is copied from memory to the output chips. These chips then drive the output devices.
The input and output scans often confuse the beginner, but they are important. The input scan takes a snapshot of the inputs, and solves the logic. This prevents potential problems that might occur if an input that is used in multiple places in the ladder logic program changed while half way through a ladder scan. Thus changing the behaviors of half of the ladder logic program. This problem could have severe effects on complex programs that are developed later in the book. One side effect of the input scan is that if a change in input is too short in duration, it might fall between input scans and be missed.
When the PLC is initially turned on the normal outputs will be turned off. This does not affect the values of the inputs.
3 。1 The Input and Output Scans
When the inputs to the PLC are scanned the physical input values are copied into memory. When the outputs to a PLC are scanned they are copied from memory to the physical outputs. When the ladder logic is scanned it uses the values in memory, not the actual input or output values. The primary reason for doing this is so that if a program uses an input value in multiple places, a change in the input value will not invalidate the logic. Also, if output bits were changed as each bit was changed, instead of all at once at the end of the scan the PLC would operate much slower.
3 。2 The Logic Scan
Ladder logic programs are modelled after relay logic. In relay logic each element in the ladder will switch as quickly as possible. But in a program elements can only be examines one at a time in a fixed sequence. Consider the ladder logic in Figure 4, the ladder logic will be interpreted left-to-right, top-to-bottom. In the figure the ladder logic scan begins at the top rung. At the end of the rung it interprets the top output first, then the output branched below it. On the second rung it solves branches, before moving along the ladder logic rung.
Figure 4 Ladder Logic Execution Sequence
The logic scan sequence become important when solving ladder logic programs which use outputs as inputs. It also becomes important when considering output usage. Consider Figure 5, the first line of ladder logic will examine input A and set output X to have the same value. The second line will examine input B and set the output X to have the opposite value. So the value of X was only equal to A until the second line of ladder logic was scanned. Recall that during the logic scan the outputs are only changed in memory, the actual outputs are only updated when the ladder logic scan is complete. Therefore the output scan would update the real outputs based upon the second line of ladder logic, and the first line of ladder logic would be ineffective.
Figure 5 A Duplicated Output Error
4 。 PLC STATUS
The lack of keyboard, and other input-output devices is very noticeable on a PLC. On the front of the PLC there are normally limited status lights. Common lights indicate;
power on - this will be on whenever the PLC has power
program running - this will often indicate if a program is running, or if no program is running
fault - this will indicate when the PLC has experienced a major hardware or software problem
These lights are normally used for debugging. Limited buttons will also be provided for PLC hardware. The most common will be a run/program switch that will be switched to program when maintenance is being conducted, and back to run when in production. This switch normally requires a key to keep unauthorized personnel from altering the PLC program or stopping execution. A PLC will almost never have an on-off switch or reset button on the front. This needs to be designed into the remainder of the system.
The status of the PLC can be detected by ladder logic also. It is common for programs to check to see if they are being executed for the first time, as shown in Figure 6. The ’first scan’ input will be true on the very first time the ladder logic is scanned, but false on every other scan. In this case the address for ’first scan’ in a PLC-5 is ’S2:1/14’. With the logic in the example the first scan will seal on ’light’, until ’clear’ is turned on. So the light will turn on after the PLC has been turned on, but it will turn off and stay off after ’clear’ is turned on. The ’first scan’ bit is also referred to at the ’first pass’ bit.
Figure 6 An program that checks for the first scan of the PLC
5 。 MEMORY TYPES
There are a few basic types of computer memory that are in use today.
RAM (Random Access Memory) - this memory is fast, but it will lose its contents when power is lost, this is known as volatile memory. Every PLC uses this memory for the central CPU when running the PLC.
ROM (Read Only Memory) - this memory is permanent and cannot be erased. It is often used for storing the operating system for the PLC.
EPROM (Erasable Programmable Read Only Memory) - this is memory that can be programmed to behave like ROM, but it can be erased with ultraviolet light and reprogrammed.
EEPROM (Electronically Erasable Programmable Read Only Memory) – This memory can store programs like ROM. It can be programmed and erased using a voltage, so it is becoming more popular than EPROMs.
All PLCs use RAM for the CPU and ROM to store the basic operating system for the PLC. When the power is on the contents of the RAM will be kept, but the issue is what happens when power to the memory is lost. Originally PLC vendors used RAM with a battery so that the memory contents would not be lost if the power was lost. This method is still in use, but is losing favor. EPROMs have also been a popular choice for programming PLCs. The EPROM is programmed out of the PLC, and then placed in the PLC. When the PLC is turned on the ladder logic program on the EPROM is loaded into the PLC and run. This method can be very reliable, but the erasing and programming technique can be time consuming. EEPROM memories are a permanent part of the PLC, and programs can be stored in them like EPROM. Memory costs continue to drop, and newer types (such as flash memory) are becoming available, and these changes will continue to impact PLCs.
6 。 SOFTWARE BASED PLCS
The dropping cost of personal computers is increasing their use in control, including the replacement of PLCs. Software is installed that allows the personal computer to solve ladder logic, read inputs from sensors and update outputs to actuators. These are important to mention here because they don’t obey the previous timing model. For example, if the computer is running a game it may slow or halt the computer. This issue and others are currently being investigated and good solutions should be expected soon.
7 。 SUMMARY
? A PLC and computer are similar with inputs, outputs, memory, etc.
? The PLC continuously goes through a cycle including a sanity check, input scan, logic scan, and output scan.
? While the logic is being scanned, changes in the inputs are not detected, and the outputs are not updated.
? PLCs use RAM, and sometime EPROMs are used for permanent programs.
8 。 PRACTICE PROBLEMS
1. Does a PLC normally contain RAM, ROM, EPROM and/or batteries?
2. What are the indicator lights on a PLC used for?
3. A PLC can only go through the ladder logic a few times per second. Why?
4. What will happen if the scan time for a PLC is greater than the time for an input pulse? Why?
5. What is the difference between a PLC and a desktop computer?
6. Why do PLCs do a self check every scan?
7. Will the test time for a PLC be long compared to the time required for a simple program?
8. What is wrong with the following ladder logic? What will happen if it is used?
9. What is the address for a memory location that indicates when a PLC has just been turned on?
9 。 PRACTICE PROBLEM SOLUTIONS
1. Every PLC contains RAM and ROM, but they may also contain EPROM or batteries.
2. Diagnostic and maintenance
3. Even if the program was empty the PLC would still need to scan inputs and outputs, and do a self check.
4. The pulse may be missed if it occurs between the input scans
5. Some key differences include inputs, outputs, and uses. A PLC has been designed for the factory floor, so it does not have inputs such as keyboards and mice (although some newer types can). They also do not have outputs such as a screen or sound. Instead they have inputs and outputs for voltages and current. The PLC runs user designed programs for specialized tasks, whereas on a personal computer it is uncommon for a user to program their system.
6. This helps detect faulty hardware or software. If an error were to occur, and the PLC continued operating, the controller might behave in an unpredictable way and become dangerous to people and equipment. The self check helps detect these types of faults, and shut the system down safely.
7. Yes, the self check is equivalent to about 1ms in many PLCs, but a single program instruction is about 1 micro second.
8. The normal output Y is repeated twice. In this example the value of Y would always match B, and the earlier rung with A would have no effect on Y.
9. S2:1/14 for micro logy, S2:1/15 for PLC-5
可編程邏輯控制器和控制系統(tǒng)
W. Bolton 《計(jì)算機(jī)和結(jié)構(gòu)學(xué)報(bào)》
2004年4月28收稿; 2004年11月3日修訂;2004年11月29定稿;2005年1月29日提供在線下載
摘要:早期的電氣控制系統(tǒng)要在繼電器、接觸器等復(fù)雜系統(tǒng)組成的系統(tǒng)下轉(zhuǎn)運(yùn)。有一個(gè)很長的設(shè)計(jì)周期,并且體積大、成本高,沒有數(shù)據(jù)處理、通信功能和必須手動等缺陷。PLC控制系統(tǒng)具有控制速度、連接電轉(zhuǎn)運(yùn)等性能,并且可靠性和可維護(hù)性好的,易于安裝、維修和改進(jìn)等。隨著經(jīng)濟(jì)的發(fā)展,越來越多的轉(zhuǎn)運(yùn)從手動到自動,并逐漸形成了機(jī)械化和自動化。
PLC在電氣控制系統(tǒng)中的應(yīng)用,可以實(shí)現(xiàn)自動控制,操作簡單,降低系統(tǒng)運(yùn)行成本。通信和數(shù)據(jù)連接選項(xiàng)使得FX1N在數(shù)量上的通信和特殊功能模塊等重要功能的完美應(yīng)用。主要項(xiàng)目包括:設(shè)備分析和一個(gè)系統(tǒng)明確的控制要求,PLC的分析選擇,確定系統(tǒng)的I/O接口的數(shù)量和類型,控制工藝設(shè)計(jì)和控制程序。
關(guān)鍵詞:PLC,控制系統(tǒng),I / O點(diǎn)
1.PLC介紹
PLCS(可編程邏輯控制器)是用于各種自動控制系統(tǒng)和過程的可控網(wǎng)絡(luò)集線器。他們包含多個(gè)輸入輸出,輸入輸出是用晶體管和其它電路,模擬開關(guān)和繼電器來控制設(shè)備的。PLCS用軟件接口,標(biāo)準(zhǔn)計(jì)算器接口,專門的語言和網(wǎng)絡(luò)設(shè)備編程。
可編程邏輯控制器I/O通道規(guī)則包括所有的輸入觸點(diǎn)和輸出觸點(diǎn),擴(kuò)展能力和最大數(shù)量的通道。觸點(diǎn)數(shù)量是輸入點(diǎn)和輸出點(diǎn)的總和。PLCS可以指定這些值的任何可能的組合。擴(kuò)展單元可以被堆?;蚧ハ噙B接來增加總的控制能力。最大數(shù)量的通道是在一個(gè)擴(kuò)展系統(tǒng)中輸入和輸出通道的最大總數(shù)量。PLC系統(tǒng)規(guī)則包括掃描時(shí)間,指令數(shù)量,數(shù)據(jù)存儲和程序存儲。掃描時(shí)間是 PLC需要的用來檢測輸入輸出模塊的時(shí)間。指令是用于PLC軟件(例如數(shù)學(xué)運(yùn)算)的標(biāo)準(zhǔn)操作。數(shù)據(jù)存儲是存儲數(shù)據(jù)的能力。程序存儲是控制軟件的能力。
用于可編程邏輯控制器的輸入設(shè)備包括DC,AC,中間繼電器,熱電偶,RTD,頻率或脈沖,晶體管和中斷信號輸入;輸出設(shè)備包括DC,AC,繼電器,中間繼電器,頻率或脈沖,晶體管,三端雙向可控硅開關(guān)元件;PLC的編程設(shè)備包括控制面板,手柄和計(jì)算機(jī)。
可編程邏輯控制器用各種軟件編程語言來控制。這些語言包括IEC61131-3,順序執(zhí)行表(SFC),動作方塊圖(FBD),梯形圖(LD),結(jié)構(gòu)文本(ST),指令序列(IL),繼電器梯形圖(RIL),流程圖,C語言和Basic語言。IEC61131-3編程環(huán)境能支持五種語言,用國際標(biāo)準(zhǔn)加以規(guī)范,分別為SFC,F(xiàn)BD,LD,ST和IL。這便允許了多賣主兼容性和多種語言編程。SFC是一種圖表語言,它提供了編程順序的配合,就能支持順序選擇和并列選擇,二者擇其一即可。FBD用一種大的運(yùn)行庫,以圖表形式建立了一些復(fù)雜的過程。標(biāo)準(zhǔn)數(shù)學(xué)和邏輯運(yùn)行可以與用戶交流和接口運(yùn)行相結(jié)合。LD是適用于離散控制和互鎖邏輯的圖表語言。它在離散控制上與FBD是完全兼容的。ST是一種文本語言,用于復(fù)雜的數(shù)學(xué)過程和計(jì)算,不太適用于圖表語言。IL是與組合編碼相似的低級語言。它用在相對比較簡單的邏輯指令。繼電器梯形圖或梯形圖是適用于可編程邏輯控制器的重要的編程語言。梯形圖編程是設(shè)計(jì)成繼電器邏輯程序的圖表表示法。流程圖是一種圖表語言,用于在一個(gè)控制器或應(yīng)用軟件中描述順序操作,它用于建立有標(biāo)準(zhǔn)組件的可循環(huán)使用的運(yùn)行庫。C語言是一種高級編程語言,適用于處理最復(fù)雜的計(jì)算,連續(xù)的數(shù)據(jù)采集任務(wù)。它典型地在PC機(jī)上運(yùn)行調(diào)試。BASIC語言是用于處理數(shù)據(jù)的連續(xù)的數(shù)字采集和接口運(yùn)行的高級語言。
可編程邏輯控制器也規(guī)范了許多計(jì)算機(jī)接口設(shè)備,網(wǎng)絡(luò)規(guī)則和特色。PLC能源設(shè)備和運(yùn)行環(huán)境也是非常重要的。
2.指令
對于簡單的編程,繼電器型P
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