外文翻譯---液壓agc系統(tǒng)故障診斷策略的研究

1、<p>　　附錄3 外文譯文及原文</p><p>　　譯文 液壓AGC系統(tǒng)故障診斷策略的研究</p><p>　　由于軋機(jī)自動(dòng)化水平及對(duì)板帶材的質(zhì)量要求越來越高，對(duì)軋機(jī)執(zhí)行機(jī)構(gòu)及控制系統(tǒng)性能的要求也越來越高。目前，液壓技術(shù)的應(yīng)用程度和水平，已成為冶金設(shè)備技術(shù)水平高低的一項(xiàng)衡量指標(biāo)。其中液壓AGC(Automatic Gauge Control)系統(tǒng)是所有冶金設(shè)備中液壓技術(shù)

2、應(yīng)用的典型代表，是現(xiàn)代化軋機(jī)設(shè)備的核心技術(shù)。液壓AGC系統(tǒng)運(yùn)行狀態(tài)的好壞，直接決定了軋機(jī)的工作可靠性。長(zhǎng)期以來，由于機(jī)械設(shè)備水平的整體差距，我國(guó)的軋機(jī)設(shè)備主要依賴進(jìn)口，在技術(shù)特別是核心技術(shù)方面受到限制。雖然近年來在先進(jìn)技術(shù)的應(yīng)用方面有重大突破，但仍局限在單機(jī)應(yīng)用的水平。因此，開展液壓AGC系統(tǒng)故障診斷技術(shù)的研究不僅對(duì)提高軋機(jī)設(shè)備的生產(chǎn)率、提高設(shè)備的維護(hù)管理水平具有重要意義，同時(shí)也對(duì)提高國(guó)產(chǎn)軋機(jī)設(shè)備的應(yīng)用水平具有重要的社會(huì)意義。</

3、p><p>　　圖2-1 軋機(jī)液壓AGC系統(tǒng)功能框圖</p><p>　　2.1 液壓AGC系統(tǒng)的組成及工藝特點(diǎn)</p><p>　　2.1.1 液壓AGC系統(tǒng)的組成</p><p>　　板帶軋機(jī)的AGC系統(tǒng)通過測(cè)厚儀、位移傳感器、壓力傳感器和張力計(jì)等對(duì)相應(yīng)參數(shù)的連續(xù)測(cè)量，連續(xù)調(diào)整液壓壓下缸位移、壓力以及張力或軋制速度等，控制板帶材的厚差。

4、此外，油膜厚度變化補(bǔ)償、軋輥偏心補(bǔ)償、前饋控制、物流控制及速度張力優(yōu)化等功能使板厚精度得到進(jìn)一步的提高[59]。其中液壓AGC系統(tǒng)是其中的核心設(shè)備。</p><p>　　從功能上，液壓AGC系統(tǒng)分為液壓控制系統(tǒng)部分和液壓能源部分。</p><p>　　1. 液壓控制系統(tǒng)部分 控制系統(tǒng)中由電液伺服閥控制壓下油缸，實(shí)現(xiàn)軋機(jī)輥縫或軋制壓力的設(shè)定與控制。為了提高控制系統(tǒng)的響應(yīng)性能，一般采用電液伺

5、服閥控制油缸的一腔（工作腔），另一腔（背壓腔）則由能源部分提供一個(gè)恒值壓力。從控制功能出發(fā)，一個(gè)完整的液壓AGC系統(tǒng)由若干個(gè)厚度自動(dòng)控制系統(tǒng)組成，其中最主要的控制環(huán)有(見圖2-1)[59,60]：</p><p>　　壓下缸位置閉環(huán)1 隨軋制條件變化及時(shí)準(zhǔn)確地控制壓下位移。xp1、xp2分別是操作側(cè)和傳動(dòng)側(cè)活塞相對(duì)缸體的位移，取其平均值xpd作為實(shí)測(cè)位移值，xp0為給定信號(hào)，Δxp是測(cè)厚儀監(jiān)控環(huán)的反饋量。<

6、;/p><p>　　軋制壓力閉環(huán) 2 通過控制軋制壓力來達(dá)到控制厚度的目的。Pd是軋制壓力的實(shí)測(cè)值，Ps為初始給定值，ΔP為修正值。</p><p>　　測(cè)厚儀監(jiān)控閉環(huán) 3 消除軋輥磨損、熱膨脹及設(shè)定值誤差等的影響。Mp為軋機(jī)縱向剛度，W為軋件的塑性剛度系數(shù)，hd為實(shí)測(cè)軋件厚度，hs為設(shè)定軋制厚度。</p><p>　　2. 液壓能源部分 液壓AGC系統(tǒng)中，液壓能

7、源的功能是為液壓控制系統(tǒng)提供壓力穩(wěn)定的、清潔的工作介質(zhì)，為電液伺服閥提供穩(wěn)定的閥前壓力，保證電液伺服系統(tǒng)的控制性能[61~65]，同時(shí)也為壓下油缸的背壓腔提供壓力穩(wěn)定的工作介質(zhì)。液壓AGC系統(tǒng)的能源一般采用恒壓變量泵-蓄能器-安全閥式的結(jié)構(gòu)形式，此外，為了保證系統(tǒng)工作介質(zhì)的清潔度、溫度等，在能源部分設(shè)置了壓力油高壓過濾器和回油低壓過濾器、冷卻器等部件。</p><p>　　2.1.2 液壓AGC系統(tǒng)的工藝特點(diǎn)&

8、lt;/p><p>　　液壓AGC系統(tǒng)的可靠運(yùn)行是整個(gè)軋機(jī)系統(tǒng)正常化生產(chǎn)的保證。由于液壓AGC系統(tǒng)是一復(fù)雜的機(jī)、電、液綜合系統(tǒng)，機(jī)械系統(tǒng)、電氣系統(tǒng)和液壓系統(tǒng)中任一系統(tǒng)或其某一部件的故障都會(huì)引發(fā)整個(gè)系統(tǒng)產(chǎn)生故障。因此，液壓AGC系統(tǒng)的維護(hù)和故障診斷具有相當(dāng)?shù)碾y度。</p><p>　　在現(xiàn)代液壓AGC系統(tǒng)中，設(shè)計(jì)時(shí)大都采用了可靠性設(shè)計(jì)技術(shù)，例如液壓泵、過濾器、傳感器、控制器等采用冗余設(shè)計(jì)，液壓系

9、統(tǒng)的一些基本參量如油箱液位、油溫、過濾器堵塞報(bào)警、壓力等都設(shè)計(jì)了監(jiān)測(cè)點(diǎn)，此外，還有直接參與控制的位移和壓力信號(hào)等。對(duì)于液壓系統(tǒng)的一些簡(jiǎn)單故障，可以依據(jù)這些信號(hào)狀態(tài)，由有經(jīng)驗(yàn)的操作技術(shù)人員進(jìn)行故障判斷和處理。然而，液壓AGC系統(tǒng)是一個(gè)集機(jī)、電、液于一體的綜合控制系統(tǒng)，系統(tǒng)的故障形式和原因也是多方面的，從功能上，系統(tǒng)不僅有靜態(tài)性能指標(biāo)，還有動(dòng)態(tài)性能指標(biāo)。系統(tǒng)中的信號(hào)也是復(fù)雜多樣的，有一部分是隨時(shí)間變化較慢的緩變信號(hào)（如油箱液位、油溫等），而

10、另一些是瞬變的高頻信號(hào)。同時(shí)，由于液壓系統(tǒng)本身的特點(diǎn)（如動(dòng)力傳遞的封閉性、參數(shù)的可測(cè)性差等），因此，單憑經(jīng)驗(yàn)，僅僅依靠這些信號(hào)還不能對(duì)系統(tǒng)的故障進(jìn)行分析處理，無法對(duì)系統(tǒng)進(jìn)行全面、準(zhǔn)確的故障診斷和預(yù)報(bào)。為此，必須依據(jù)設(shè)備的結(jié)構(gòu)特點(diǎn)和故障機(jī)理增加一些監(jiān)控點(diǎn)，以獲取能夠反映系統(tǒng)功能的狀態(tài)信號(hào)，并采用先進(jìn)的故障診斷技術(shù)（如專家系統(tǒng)等）進(jìn)行液壓AGC系統(tǒng)的狀態(tài)監(jiān)測(cè)和故障診斷。</p><p>　　2.2 液壓AGC系統(tǒng)故

11、障診斷的策略</p><p>　　2.2.1 面向系統(tǒng)對(duì)象的實(shí)用診斷策略的提出</p><p>　　針對(duì)液壓AGC系統(tǒng)的故障診斷技術(shù)對(duì)于現(xiàn)代化軋機(jī)的生產(chǎn)正?；驮O(shè)備維護(hù)具有重要意義。但如何進(jìn)行液壓AGC系統(tǒng)的狀態(tài)監(jiān)測(cè)和故障診斷呢？是對(duì)構(gòu)成液壓AGC系統(tǒng)的元件（諸如液壓泵、電液伺服閥等）實(shí)施監(jiān)測(cè)，還是注重液壓AGC系統(tǒng)所承擔(dān)的工藝任務(wù)、從生產(chǎn)工藝對(duì)液壓AGC系統(tǒng)的特殊要求出發(fā)，對(duì)液壓AGC

12、系統(tǒng)中具有表征意義的參量進(jìn)行監(jiān)控？</p><p>　　針對(duì)液壓系統(tǒng)中關(guān)鍵元件（如液壓泵、液壓缸或馬達(dá)、溢流閥、電液伺服閥等）的故障機(jī)理或失效形式的研究，國(guó)內(nèi)外已開展了大量的研究，并取得了一些重要的理論或應(yīng)用成果[23~30]，為液壓系統(tǒng)故障診斷技術(shù)的深入研究奠定了基礎(chǔ)，近年來，國(guó)內(nèi)外學(xué)者對(duì)于液壓系統(tǒng)的故障診斷采用了多種方法進(jìn)行了廣泛的研究[66~70]。但傳統(tǒng)上，液壓系統(tǒng)故障診斷技術(shù)的研究比較偏重于研究系統(tǒng)中關(guān)

13、鍵元件的故障機(jī)理，而對(duì)生產(chǎn)工藝賦予液壓設(shè)備的使命，對(duì)液壓設(shè)備完成生產(chǎn)工藝具有優(yōu)勢(shì)的功能指標(biāo)缺乏關(guān)注[71,72]。</p><p>　　在實(shí)際生產(chǎn)系統(tǒng)中，要使液壓設(shè)備發(fā)揮正常的功能，對(duì)元件的關(guān)注是必須的，但關(guān)注的重點(diǎn)應(yīng)是元件的功能指標(biāo)，而不是元件的具體失效形式。因?yàn)閷?duì)實(shí)際系統(tǒng)而言，元件損壞了可以更換，并且，在現(xiàn)代液壓系統(tǒng)的設(shè)計(jì)中都采用了冗余設(shè)計(jì)技術(shù)，必要時(shí)可以進(jìn)行切換使用，可以保證系統(tǒng)的正常工作。損壞的元件可以通

14、過離線在實(shí)驗(yàn)室中進(jìn)行檢測(cè)和修復(fù)，必要時(shí)購(gòu)買新的元件。因此，針對(duì)軋機(jī)液壓AGC系統(tǒng)故障診斷技術(shù)的研究，應(yīng)在前人對(duì)系統(tǒng)關(guān)鍵元件進(jìn)行的故障診斷研究之基礎(chǔ)上，注重監(jiān)控液壓AGC系統(tǒng)的功能指標(biāo)，采用在線診斷與離線監(jiān)測(cè)相結(jié)合的方法，利用先進(jìn)的智能故障診斷技術(shù)對(duì)液壓AGC系統(tǒng)進(jìn)行狀態(tài)監(jiān)測(cè)與故障診斷。</p><p>　　注重電液伺服系統(tǒng)動(dòng)態(tài)特性的監(jiān)測(cè) 電液伺服系統(tǒng)具有調(diào)節(jié)速度快、頻響高的特點(diǎn)，對(duì)于其靜態(tài)特性的研究和計(jì)算已很成

15、熟，但由于影響電液伺服系統(tǒng)動(dòng)態(tài)性能的因素很多、參數(shù)選取不準(zhǔn)等原因，理論計(jì)算與系統(tǒng)的實(shí)際狀態(tài)之間存在較大的差別，并且在設(shè)備使用過程中，由于磨損、元器件老化、參數(shù)漂移、各種系統(tǒng)的耦合干擾及維護(hù)調(diào)試不當(dāng)?shù)?，?huì)導(dǎo)致液壓AGC系統(tǒng)的性能下降，嚴(yán)重時(shí)，會(huì)影響產(chǎn)品質(zhì)量和設(shè)備的可靠運(yùn)行。因此，應(yīng)建立液壓AGC系統(tǒng)動(dòng)態(tài)性能監(jiān)測(cè)裝置，在線監(jiān)測(cè)液壓AGC系統(tǒng)的動(dòng)態(tài)性能并顯示其變化趨勢(shì)，依據(jù)監(jiān)測(cè)數(shù)據(jù)和經(jīng)驗(yàn)，建立故障樣本和判據(jù)，利用專家系統(tǒng)進(jìn)行故障診斷。<

16、/p><p>　　注重電液伺服系統(tǒng)能源參數(shù)的監(jiān)測(cè) 液壓能源的功能是為液壓控制系統(tǒng)提供壓力穩(wěn)定的、清潔的工作介質(zhì)。液壓系統(tǒng)中各功能點(diǎn)的壓力反映了系統(tǒng)的主要功能特征，如液壓泵前的壓力反映了吸油濾油器的堵塞情況，泵前后的壓力可以反映泵的運(yùn)行狀態(tài)，蓄能器組后的壓力可以快速提供判斷系統(tǒng)壓力失常或電氣控制失誤等故障，故對(duì)各功能點(diǎn)處的壓力監(jiān)測(cè)是能源系統(tǒng)性能監(jiān)測(cè)的重點(diǎn)。液壓系統(tǒng)70%的故障是由于工作介質(zhì)的污染引起的，所以在液壓系統(tǒng)

17、中，都對(duì)油液的過濾采取了必要的措施，特別是電液伺服系統(tǒng)中，更采取了過濾器冗余設(shè)計(jì)方式，以保證介質(zhì)的清潔。盡管如此，由于系統(tǒng)中更換元件、管道破裂等原因，仍會(huì)造成工作介質(zhì)的污染，因此，應(yīng)對(duì)油液作周期檢測(cè)。油液的溫度也會(huì)對(duì)電液伺服系統(tǒng)的性能產(chǎn)生影響，對(duì)系統(tǒng)油液溫度的監(jiān)測(cè)和控制也十分重要。此外，液位的變化等也從某種程度上反映了系統(tǒng)的運(yùn)行狀態(tài)。</p><p>　　在線監(jiān)測(cè)與離線監(jiān)測(cè)相結(jié)合 設(shè)備狀態(tài)維護(hù)和故障診斷必須是在

18、設(shè)備運(yùn)行中對(duì)設(shè)備進(jìn)行狀態(tài)監(jiān)測(cè)和故障診斷。但對(duì)于實(shí)際系統(tǒng)，基于系統(tǒng)功能指標(biāo)的監(jiān)測(cè)時(shí)，可以將離線監(jiān)測(cè)技術(shù)與在線監(jiān)測(cè)技術(shù)相結(jié)合。例如，對(duì)于電液伺服系統(tǒng)的關(guān)鍵部件——電液伺服閥，要進(jìn)行全面的在線監(jiān)測(cè)，技術(shù)相當(dāng)復(fù)雜，且由于系統(tǒng)狀態(tài)復(fù)雜，監(jiān)測(cè)也不一定準(zhǔn)確，而在實(shí)驗(yàn)室中，對(duì)于電液伺服閥的檢測(cè)和修復(fù)技術(shù)已相當(dāng)完善，因此，可以將電液伺服閥更換下來，送往實(shí)驗(yàn)室進(jìn)行檢測(cè)、維護(hù)，鑒定其性能。對(duì)于油液清潔度的檢測(cè)盡管可以做到在線連續(xù)監(jiān)測(cè)，但一般情況下并不必如此，

19、完全可以按一定周期進(jìn)行采樣檢測(cè)，實(shí)現(xiàn)對(duì)油液的監(jiān)測(cè)。在線監(jiān)測(cè)與離線監(jiān)測(cè)相結(jié)合，不僅可以降低診斷專家系統(tǒng)的成本，更重要的是可以提高專家系統(tǒng)的故障診斷速度，實(shí)現(xiàn)設(shè)備的預(yù)知維修。</p><p>　　2.2.2 診斷系統(tǒng)的“模塊化”診斷策略</p><p>　　液壓AGC系統(tǒng)是一復(fù)雜的機(jī)、電、液綜合系統(tǒng)，因此，機(jī)械系統(tǒng)、電氣系統(tǒng)和液壓系統(tǒng)中任一系統(tǒng)或其中某一部件的故障都會(huì)引發(fā)整個(gè)系統(tǒng)產(chǎn)生故障。本

20、文對(duì)機(jī)械系統(tǒng)和電氣系統(tǒng)（包括各類傳感器）的故障不做研究，只重點(diǎn)研究液壓系統(tǒng)本身的故障機(jī)理和診斷方法。</p><p>　　如前所述，從功能上，液壓AGC系統(tǒng)分為液壓控制系統(tǒng)部分和液壓能源部分。液壓能源部分的功能是為控制系統(tǒng)部分提供壓力穩(wěn)定、清潔的工作介質(zhì)，而對(duì)于控制系統(tǒng)部分，其動(dòng)態(tài)性能指標(biāo)才是系統(tǒng)狀態(tài)監(jiān)測(cè)和故障診斷的重點(diǎn)。從狀態(tài)監(jiān)測(cè)及故障診斷的角度出發(fā)，兩部分系統(tǒng)的狀態(tài)信息無論是形式還是特征都有很大的區(qū)別，且沒有

21、很大的關(guān)聯(lián)性，因此，對(duì)液壓AGC系統(tǒng)的狀態(tài)監(jiān)測(cè)和故障診斷可以劃分為兩個(gè)子系統(tǒng)（診斷模塊），對(duì)控制系統(tǒng)和系統(tǒng)能源分別進(jìn)行各自的狀態(tài)監(jiān)測(cè)和故障診斷，并使兩個(gè)診斷系統(tǒng)協(xié)同工作，共同完成液壓AGC系統(tǒng)的狀態(tài)監(jiān)測(cè)與故障診斷。診斷系統(tǒng)“模塊化”具有以下優(yōu)點(diǎn)：</p><p>　　模塊化診斷系統(tǒng)中各模塊要比相應(yīng)非模塊化診斷系統(tǒng)簡(jiǎn)單得多，因此，各診斷模塊的知識(shí)庫(kù)（狀態(tài)信息、推理規(guī)則等）容量可以大大縮減，診斷系統(tǒng)易于構(gòu)造，當(dāng)利用神

22、經(jīng)網(wǎng)絡(luò)進(jìn)行系統(tǒng)的自學(xué)習(xí)時(shí)，其學(xué)習(xí)性能和泛化特性易于得到保證；</p><p>　　相對(duì)整個(gè)系統(tǒng)，各模塊的輸入輸出信息大大簡(jiǎn)化，且推理路徑得到縮短，因此，各自模塊的推理速度、學(xué)習(xí)能力等可以大大提高，利用并行處理技術(shù)，可以實(shí)現(xiàn)系統(tǒng)故障診斷的實(shí)時(shí)性要求；</p><p>　　在實(shí)際應(yīng)用中，一般可獨(dú)立并行對(duì)待各模塊，使得模塊化診斷系統(tǒng)更具應(yīng)用的靈活性和現(xiàn)場(chǎng)的適應(yīng)性；</p><

23、p>　　模塊化診斷系統(tǒng)的診斷結(jié)論更易于解釋，因?yàn)樵\斷系統(tǒng)中各診斷模塊的任務(wù)明確，功能確定，且各診斷模塊間的關(guān)系清楚，使得整個(gè)診斷系統(tǒng)的工作過程更為明朗；</p><p>　　模塊化結(jié)構(gòu)有利于今后將其它子系統(tǒng)的狀態(tài)監(jiān)測(cè)與故障診斷模塊互相融合，開展整個(gè)液壓AGC系統(tǒng)的故障診斷與狀態(tài)檢測(cè)技術(shù)的研究。</p><p>　　2.2.3 液壓AGC系統(tǒng)基于神經(jīng)網(wǎng)絡(luò)的模糊專家系統(tǒng)診斷策略<

24、/p><p>　　液壓系統(tǒng)的故障診斷技術(shù)以吸收和應(yīng)用其它領(lǐng)域的一些成果為基礎(chǔ)，特別是信號(hào)處理、模式識(shí)別、模糊推理和神經(jīng)網(wǎng)絡(luò)等領(lǐng)域的理論方法，結(jié)合液壓系統(tǒng)特有的失效形式和故障機(jī)理，建立相應(yīng)的知識(shí)庫(kù)和規(guī)則庫(kù)，對(duì)提取的狀態(tài)監(jiān)測(cè)信號(hào)進(jìn)行模式識(shí)別或分類，對(duì)系統(tǒng)故障進(jìn)行診斷、故障原因分析、故障定位和故障預(yù)報(bào)等。許多應(yīng)用實(shí)例表明，結(jié)合人工智能和領(lǐng)域?qū)＜抑R(shí)的智能型專家系統(tǒng)是進(jìn)行液壓系統(tǒng)故障診斷的有效途徑[10,11]。</p

25、><p>　　故障診斷的過程是根據(jù)診斷對(duì)象出現(xiàn)的異常征兆，基于先驗(yàn)知識(shí)（故障樣本庫(kù)）通過一定的推理規(guī)則，判斷對(duì)象的故障部位并查明引起故障的可能原因。模糊專家系統(tǒng)可基于規(guī)模較小的故障樣本庫(kù)和推理規(guī)則，快速判定故障，然而，由于其隸屬函數(shù)和模糊規(guī)則不易調(diào)整和修改，存在知識(shí)獲取的瓶頸、推理的不確定性及自學(xué)習(xí)困難等問題。另一方面，神經(jīng)網(wǎng)絡(luò)有很好的學(xué)習(xí)能力，可通過現(xiàn)場(chǎng)系統(tǒng)的狀態(tài)監(jiān)測(cè)信號(hào)進(jìn)行學(xué)習(xí)，對(duì)未知知識(shí)進(jìn)行處理和補(bǔ)充。二者結(jié)合

26、，可以發(fā)揮它們各自的優(yōu)勢(shì)，適合進(jìn)行液壓AGC系統(tǒng)的故障診斷。圖2-2給出了液壓AGC故障診斷專家系統(tǒng)的基本結(jié)構(gòu)。</p><p>　　圖2-2所示的液壓AGC故障診斷系統(tǒng)中，知識(shí)以兩種方式進(jìn)行描述：一種是通過實(shí)驗(yàn)和總結(jié)，將事實(shí)知識(shí)和專家經(jīng)驗(yàn)形式化成模糊規(guī)則，存儲(chǔ)于知識(shí)庫(kù)中，并用相應(yīng)的模糊神經(jīng)網(wǎng)絡(luò)對(duì)模糊規(guī)則進(jìn)行優(yōu)化；另一種是通過現(xiàn)場(chǎng)歷史數(shù)據(jù)對(duì)模糊神經(jīng)網(wǎng)絡(luò)推理機(jī)進(jìn)行訓(xùn)練，獲取非確定性知識(shí)，并通過人機(jī)對(duì)話對(duì)知識(shí)庫(kù)進(jìn)行補(bǔ)

27、充。協(xié)調(diào)機(jī)構(gòu)針對(duì)不同情況用模糊推理和神經(jīng)網(wǎng)絡(luò)對(duì)系統(tǒng)進(jìn)行診斷，得出相應(yīng)的診斷結(jié)果。</p><p>　　綜上，本文針對(duì)軋機(jī)液壓AGC系統(tǒng)采取的診斷策略是：</p><p>　　1. 面向系統(tǒng)對(duì)象的診斷策略 在前人對(duì)系統(tǒng)關(guān)鍵元件進(jìn)行的故障診斷研究之基礎(chǔ)上，注重監(jiān)控液壓AGC系統(tǒng)的功能指標(biāo)。對(duì)液壓能源部分，主要監(jiān)控系統(tǒng)的壓力穩(wěn)定性，而對(duì)于控制系統(tǒng)部分，則主要監(jiān)控其動(dòng)態(tài)性能指標(biāo)。</p&g

28、t;<p>　　2. 在線診斷與離線監(jiān)測(cè)相結(jié)合 在線監(jiān)測(cè)系統(tǒng)及主要元件的功能指標(biāo)，離線檢驗(yàn)主要元件的具體失效形式。</p><p>　　3. 診斷系統(tǒng)模塊化 將診斷對(duì)象具體分為能源部分和控制系統(tǒng)部分，提高診斷系統(tǒng)的診斷速度和準(zhǔn)確度。</p><p>　　4. 模糊理論與神經(jīng)網(wǎng)絡(luò)相融合的專家系統(tǒng)診斷方法 用基于模糊推理的專家系統(tǒng)解決系統(tǒng)中知識(shí)的不確定性，并與神經(jīng)網(wǎng)絡(luò)相融合

29、以解決診斷系統(tǒng)知識(shí)的獲取、規(guī)則優(yōu)化等問題。</p><p>　　本文將基于以上的診斷策略，從液壓AGC系統(tǒng)狀態(tài)信號(hào)的提取與處理、診斷專家系統(tǒng)的結(jié)構(gòu)及其建立、診斷專家系統(tǒng)的實(shí)現(xiàn)等方面，展開針對(duì)液壓AGC系統(tǒng)的故障診斷技術(shù)的研究。</p><p>　　2.3 液壓AGC系統(tǒng)動(dòng)態(tài)性能的模擬</p><p>　　液壓AGC系統(tǒng)的動(dòng)態(tài)性能指標(biāo)是液壓AGC系統(tǒng)狀態(tài)監(jiān)測(cè)與故障診

30、斷的重點(diǎn)對(duì)象，通過液壓AGC系統(tǒng)的動(dòng)態(tài)性能的模擬，分析軋制過程中各種變化的因素對(duì)系統(tǒng)動(dòng)態(tài)品質(zhì)的影響，不僅對(duì)于液壓AGC系統(tǒng)的優(yōu)化設(shè)計(jì)具有深遠(yuǎn)意義。同時(shí)，通過對(duì)液壓AGC系統(tǒng)的機(jī)理分析和動(dòng)態(tài)模擬，還對(duì)液壓AGC故障診斷專家系統(tǒng)的深層知識(shí)（基于模型的知識(shí)如基于AR模型的AR譜等）的獲取具有指導(dǎo)作用，對(duì)液壓AGC故障診斷專家系統(tǒng)知識(shí)庫(kù)的建立和推理規(guī)則的確定具有重要意義。</p><p>　　目前，對(duì)液壓AGC系統(tǒng)的分析

31、和模擬多集中于不考慮軋機(jī)輥系及軋件本身的特性變化，將軋機(jī)輥系及軋件的變形因素作為系統(tǒng)的恒值干擾量，或是對(duì)系統(tǒng)的設(shè)定進(jìn)行補(bǔ)償，而僅研究液壓系統(tǒng)本身的響應(yīng)特性[73~75]，與實(shí)際系統(tǒng)有一定的差距。因此，建立一種全面且利于分析軋制過程中各種因素對(duì)系統(tǒng)動(dòng)態(tài)性能影響的模型，可為液壓AGC系統(tǒng)基于深層知識(shí)的智能故障診斷系統(tǒng)建立基礎(chǔ)。同時(shí)，還對(duì)軋機(jī)系統(tǒng)的優(yōu)化設(shè)計(jì)及對(duì)軋制過程的動(dòng)態(tài)模擬具有重要的意義。</p><p>　?。ㄓ?/p>

32、響油液控制容積的大小及軋機(jī)縱向剛度）及軋件塑性剛度系數(shù)等參數(shù)隨著軋制條件的變化而變化，這些因素對(duì)軋制厚度有不同的影響。另外，回油管道也影響液壓AGC系統(tǒng)的響應(yīng)能力，通過研究這些因素對(duì)軋制過程的影響，可為液壓AGC系統(tǒng)的優(yōu)化設(shè)計(jì)及軋制過程的動(dòng)態(tài)模擬提供基礎(chǔ)，同時(shí)，可為液壓AGC系統(tǒng)基于深層知識(shí)的智能故障診斷系統(tǒng)建立基礎(chǔ)。</p><p>　　圖2-8表明，軋件入口厚度的變化對(duì)軋制厚度的影響較大，因此，為獲得高的板厚

33、精度必須控制來料誤差并限制軋制速度[59]。入口厚度的變化對(duì)軋制厚度的影響與軋前厚度變化的幅值、頻率及形式有關(guān)，與幅值相同但厚度變化較慢的軋件相比，來料厚度高頻變化的軋件軋制后的厚度誤差較大。但經(jīng)過控制軋制，厚度誤差可由軋制前的60μm減少為軋制后的25μm，即軋制過程對(duì)厚度誤差具有“消差”功能。圖中（0.05～0.2）s段表示軋件帶頭進(jìn)入軋機(jī)開始軋制時(shí)的情況。</p><p>　　圖2-9顯示了軋件塑性剛度系數(shù)

34、對(duì)軋制厚度和系統(tǒng)控制壓力的影響，若系統(tǒng)設(shè)定值與實(shí)際帶鋼的塑性剛度不一致時(shí)，軋制時(shí)對(duì)厚度誤差的“消差”能力減弱。當(dāng)軋件塑性剛度系數(shù)過大時(shí)，由于控制壓力的飽和非線性等因素的影響，將難以消除來料的厚度差。</p><p>　　圖2-10顯示了油缸初始行程對(duì)軋制厚度的影響。由于油缸初始行程L0對(duì)軋機(jī)綜合縱向剛度的影響較大，L0增大意味著輥系質(zhì)量的下降和控制容積的增加，因此，油缸初始行程的改變將使系統(tǒng)的動(dòng)態(tài)性能改變，并使系

35、統(tǒng)對(duì)厚度誤差的“消差”能力減弱。</p><p><b>　　2.4 本章小結(jié)</b></p><p>　　1. 提出了液壓AGC系統(tǒng)面向?qū)ο蟮摹澳K化”故障診斷策略 通過分析實(shí)際液壓AGC系統(tǒng)的組成、工藝特點(diǎn)及實(shí)際系統(tǒng)的運(yùn)行維護(hù)特點(diǎn)，提出了面向系統(tǒng)功能特征進(jìn)行故障診斷的實(shí)用診斷策略。在總結(jié)前人針對(duì)系統(tǒng)關(guān)鍵元件進(jìn)行故障診斷的基礎(chǔ)上，重點(diǎn)研究了對(duì)于液壓系統(tǒng)功能指標(biāo)的

36、監(jiān)控及診斷方法，提出了“模塊化”診斷專家系統(tǒng)的策略，并應(yīng)用于液壓AGC系統(tǒng)的故障診斷，以提高診斷系統(tǒng)的實(shí)時(shí)性。得到的主要結(jié)論為:</p><p>　　軋機(jī)液壓AGC系統(tǒng)故障診斷技術(shù)的研究，應(yīng)在前人對(duì)系統(tǒng)關(guān)鍵元件進(jìn)行的故障診斷研究之基礎(chǔ)上，注重監(jiān)控液壓AGC系統(tǒng)的功能指標(biāo)。對(duì)液壓能源部分，主要監(jiān)控系統(tǒng)的壓力穩(wěn)定性，而對(duì)于控制系統(tǒng)部分，則主要監(jiān)控其動(dòng)態(tài)性能指標(biāo)。</p><p>　　在線診斷與

37、離線監(jiān)測(cè)相結(jié)合，不僅可以降低診斷專家系統(tǒng)的成本，更重要的是可以提高專家系統(tǒng)的故障診斷速度，實(shí)現(xiàn)設(shè)備的預(yù)知維修。采用在線診斷與離線監(jiān)測(cè)相結(jié)合的方法，在線監(jiān)測(cè)系統(tǒng)及主要元件的功能指標(biāo)，離線檢驗(yàn)主要元件的具體失效形式。</p><p>　　“模塊化”診斷專家系統(tǒng)中各診斷模塊結(jié)構(gòu)簡(jiǎn)單、任務(wù)明確，具有診斷速度快、學(xué)習(xí)能力強(qiáng)、診斷結(jié)論易于解釋等特點(diǎn)。利用并行處理技術(shù)，可以實(shí)現(xiàn)系統(tǒng)故障診斷的實(shí)時(shí)性要求，所組成的專家系統(tǒng)具有應(yīng)用

38、的靈活性和對(duì)實(shí)際系統(tǒng)的適應(yīng)性，并有利于對(duì)系統(tǒng)進(jìn)行更深入的研究。</p><p>　　2. 建立了液壓AGC系統(tǒng)的分布參數(shù)模型并對(duì)系統(tǒng)進(jìn)行了動(dòng)態(tài)性能的模擬研究 液壓AGC系統(tǒng)的動(dòng)態(tài)性能指標(biāo)是液壓AGC系統(tǒng)狀態(tài)監(jiān)測(cè)與故障診斷的重點(diǎn)對(duì)象，而實(shí)際系統(tǒng)是一個(gè)復(fù)雜的非線性時(shí)變系統(tǒng)，在一定條件下研究系統(tǒng)參數(shù)變化（如質(zhì)量、控制容積、阻尼等）對(duì)系統(tǒng)響應(yīng)特性的影響、對(duì)液壓AGC系統(tǒng)的動(dòng)態(tài)性能進(jìn)行模擬、分析軋制過程中各種變化的因素對(duì)系

39、統(tǒng)動(dòng)態(tài)品質(zhì)的影響，不僅對(duì)于液壓AGC系統(tǒng)的優(yōu)化設(shè)計(jì)具有深遠(yuǎn)意義，同時(shí)，通過對(duì)液壓AGC系統(tǒng)的機(jī)理分析和動(dòng)態(tài)模擬，還對(duì)液壓AGC故障診斷專家系統(tǒng)的深層知識(shí)（基于模型的知識(shí)如基于AR模型的AR譜等）的獲取具有指導(dǎo)作用，對(duì)液壓AGC故障診斷專家系統(tǒng)知識(shí)庫(kù)的建立和推理規(guī)則的確定具有重要意義。得到的主要結(jié)論有：</p><p>　　仿真結(jié)果表明：所建立的液壓AGC系統(tǒng)分布參數(shù)式模型是正確的。所建立的模型包含了軋機(jī)入口厚度、

40、油液控制容積、軋機(jī)彈性變形、軋件變形抗力及背壓管道動(dòng)特性等在軋制過程中變化較大的因素，因此是一種較全面且利于分析軋制過程中各種因素對(duì)最后軋制精度影響的模型。</p><p>　　系統(tǒng)供油壓力的低頻振動(dòng)對(duì)系統(tǒng)響應(yīng)性能的影響較大，低頻時(shí)，當(dāng)系統(tǒng)供油壓力的波動(dòng)值大于3%時(shí)，即對(duì)系統(tǒng)的響應(yīng)特性造成影響。所建立的液壓AGC系統(tǒng)分布參數(shù)式模型對(duì)故障診斷專家系統(tǒng)深層知識(shí)（如基于AR模型的AR參數(shù)）的獲取具有指導(dǎo)作用。</

41、p><p>　　原文 The 2nd chapter hydraulic pressure AGC system failure diagnosis strategy research</p><p>　　As the level of automation and the mill board strip of more high-quality requirements, the e

42、xecutive body of the mill and control system performance requirements are also getting higher and higher. At present, the application of hydraulic technology and the level of metallurgical equipment technology has become

43、 the level of a measure of [56 to 58].</p><p>　　One hydraulic AGC (Automatic Gauge Control) system is all metallurgical equipment hydraulic technology applications in a typical representative of the modern m

44、ill equipment core technology. AGC hydraulic systems running is good or bad, the mill decided to direct the work of reliability. For a long time, because the overall level of machinery and equipment gaps, the rolling mil

45、l in China mainly relies on imports of equipment, technology, especially in the core technology is limited. Although in r</p><p>　　2.1 hydraulic components and characteristics of AGC system</p><p&

46、gt;　　2.1.1 hydraulic system composed of AGC</p><p>　　Strip mill system through the AGC gage, displacement sensors, pressure sensors and tension of the corresponding parameters such as the continuous measurem

47、ent, continuous adjustment of hydraulic pressure cylinder displacement, pressure and tension or rolling speed, the control panel strip Thickness difference. In addition, the film thickness changes in compensation, roll e

48、ccentricity compensation, feedforward control, logistics control and optimize the speed of tension thickness, and other functi</p><p>　　From the function, AGC hydraulic system is divided into parts and hydra

49、ulic control system of hydraulic energy part.</p><p>　　1. Hydraulic control system of the control system from electro-hydraulic servo valve in the fuel tank pressure control, and roll joints or rolling mill

50、pressure settings and control. In order to improve the control system response performance, the general use of electro-hydraulic servo valve control of the fuel tank of a cavity (working cavity), another cavity (back-pre

51、ssure chamber) from some energy to provide a constant pressure. Starting from the control functions, a complete hydraulic system</p><p>　　1) location of the closed-loop cylinder pressure with a rolling condi

52、tions in a timely and accurate control of pressure displacement. xp1, xp2 are operating side and the transmission side of the cylinder piston relative displacement, comes as the average xpd measured displacement values,

53、xp0 for a given signal, Δ xp gage is monitoring the feedback of Central.</p><p>　　2) rolling through the pressure of the closed-loop control of two rolling pressure to achieve the objective of controlling th

54、e thickness. Pd is rolling pressure measured, Ps given for the initial value, Δ P value for the amendment.</p><p>　　3) Elimination of three gage monitoring closed-loop roller wear, thermal expansion and sett

55、ings, such as the impact of error. Mp for the mill vertical stiffness, W for rolling pieces of plastic stiffness coefficient, hd as measured workpiece thickness, hs set rolling for thickness.</p><p>　　2. AGC

56、 hydraulic energy of the hydraulic system, hydraulic energy is the function of the hydraulic control system to provide pressure stable, clean working media, to provide a stable Servo Valve before the pressure valve to en

57、sure that electro-hydraulic servo system The control of [61 to 65], but also for the reduction of the fuel tank pressure on the back-pressure chamber to provide a stable working media. AGC hydraulic system of energy use

58、in general variables constant pressure pump - Storage </p><p>　　2.1.2 the hydraulic system features of AGC</p><p>　　AGC's hydraulic system is reliable operation of the entire mill production

59、 of the normalization of the guarantee system. As AGC hydraulic system is a complicated machine, electricity, liquid integrated system, mechanical system, electrical system and hydraulic system in any system or one of it

60、s components will be the fault caused the system to produce failure. Therefore, AGC hydraulic system maintenance and fault diagnosis with considerable difficulty.</p><p>　　AGC in the modern hydraulic system,

61、 designed mostly by the reliability design technologies, such as hydraulic pumps, filters, sensors, controllers use of redundant design, hydraulic system some basic parameters such as tank level, oil temperature , Filter

62、s, plug the alarm, designed to monitor all the pressure points, in addition, there are directly involved in the control of the displacement and pressure signals, and so on. For some simple hydraulic system failure, can b

63、e based on these signals,</p><p>　　2.2 hydraulic system failure diagnosis strategy</p><p>　　2.2.1 object-oriented systems for the diagnosis of the proposed strategy</p><p>　　AGC for

64、 hydraulic system fault diagnosis technology for the modernization of the mill and the normalization of production equipment maintenance is of great significance. But how to carry out the hydraulic system AGC condition m

65、onitoring and fault diagnosis? » AGC is a hydraulic system components (such as the hydraulic pump, electro-hydraulic servo valve, etc.) to monitor the implementation of, or focus on hydraulic system AGC commitment o

66、f tasks, from the production process on the hydraulic syst</p><p>　　For the key components in the hydraulic system (such as hydraulic pumps, hydraulic cylinder or motor, the relief valve, electro-hydraulic s

67、ervo valve, etc.) or failure of the failure mechanism forms of research, at home and abroad have carried out a great deal of research, and made some Important theoretical or application of the results [23 to 30], for the

68、 hydraulic system fault diagnosis technology in-depth study laid the foundation in recent years, scholars at home and abroad for the hydrauli</p><p>　　In the actual production system, for hydraulic equipment

69、 to play the normal function of the components of concern is necessary, but attention should focus on the functional components of the index, rather than the specific components of failure. Because of the actual systems,

70、 components can damage the replacement and, in the modern design of the hydraulic system have been made redundant design technology and, if necessary, can use the switch, the system can guarantee the normal work. The com

71、pone</p><p>　　1. Focus on electro-hydraulic servo system dynamic monitoring of electro-hydraulic servo system adjusts speed, high-frequency response characteristics, for its static characteristics of the stu

72、dy and calculation has been very mature, but the impact of electro-hydraulic servo system because of the dynamic performance of many factors , Not allowed to select the parameters and other reasons, theoretical calculati

73、ons and the actual state of the difference between the larger and equipment used in the</p><p>　　2. Electro-hydraulic servo focus on energy parameters of the monitoring system of hydraulic energy function is

74、 to provide for the hydraulic control system pressure stable, clean working media. In the hydraulic system features a point system to reflect the pressure of the main functional characteristics, such as the hydraulic pum

75、p before the pressure of the oil-absorbing Lvyou Qi reflect the plug, before and after the pressure pump to reflect the pump running, after the group accumulator The pres</p><p>　　3. Offline and online monit

76、oring equipment to monitor state of combining the maintenance and fault diagnosis equipment must be in the running of the equipment condition monitoring and fault diagnosis. But for the actual system, based on indicators

77、 of the monitoring system, the monitoring technology could be offline and online monitoring technology integration. For example, the electro-hydraulic servo system of the key components - Servo Valve, it is necessary to

78、conduct a comprehensive on-line m</p><p>　　2.2.2 Diagnostic System "modular" strategy </p><p>　　AGC hydraulic system is a complicated machine, electricity, liquid integrated system, so

79、 mechanical system, electrical system and hydraulic system in which any system or components of a fault system as a whole will trigger a fault. In this paper, mechanical systems and electrical systems (including all type

80、s of sensors) on the fault not only focus on their own hydraulic system failure mechanism and diagnostic methods.</p><p>　　As mentioned above, from the functional, hydraulic AGC system is divided into parts

81、and hydraulic control system of hydraulic energy part. Hydraulic energy part of the function is to provide some of the pressure control system stable, clean working media, and some of the control system, its dynamic perf

82、ormance indicators is the system status monitoring and fault diagnosis of focus. From the condition monitoring and fault diagnosis point of view, the two parts of the state information system rega</p><p>　　m

83、odular system of the module than in the corresponding non-modular diagnostic system much simpler, so all of the knowledge base module (state information, reasoning rules, etc.) can be greatly reduced capacity, easy-diagn

84、ostic system construction, when the use of neural networks A system of self-learning, learning and performance characteristics of easy generalization is guaranteed;</p><p>　　relatively system as a whole, the

85、 input and output information module greatly simplified, and by shortening the path reasoning, therefore, each module of the reasoning speed, learning ability, can be greatly improved, the use of parallel processing tech

86、nology, can achieve real-time fault diagnosis system requirements;</p><p>　　in practical application, generally parallel treatment to an independent module, making modular application of the diagnostic syste

87、m more flexibility and adaptability of the scene;</p><p>　　modular system of the diagnostic conclusions more easily explained, because the diagnosis system in the clear mandate of the module, function identi

88、fication, and the diagnosis of the relationship between the modules clearly, making the whole process of diagnosis system work more uncertain;</p><p>　　modular structure is conducive to the future of other s

89、ubsystems will be the status of monitoring and fault diagnosis integration between modules, AGC in the hydraulic system fault diagnosis and state detection technology research.</p><p>　　2.2.3 AGC hydraulic s

90、ystem based on neural network fuzzy expert system diagnosis strategy</p><p>　　The hydraulic system fault diagnosis technology and applications to absorb some of the other areas of results-based, in particula

91、r, signal processing, pattern recognition, neural networks and fuzzy reasoning in areas such as the theory in light of the specific hydraulic system failure and the failure of the mechanism, The establishment of a knowle

92、dge base and corresponding rules for the extraction of state monitoring signal pattern recognition or classification, the system fault diagnosis, analy</p><p>　　Fault diagnosis process is based on the object

93、 of unusual symptoms, based on prior knowledge (the fault samples) through certain rules of reasoning, judgement target location and identification of the fault caused the possible reasons for failure. Fuzzy expert syste

94、m can be based on a smaller scale fault samples and the rules of reasoning, rapid determine fault, however, because of its membership function and fuzzy rules difficult to adapt and modify, access to knowledge of the exi

95、stence of bott</p><p>　　As shown in Figure 2-2 AGC hydraulic fault diagnosis system, the knowledge to describe two ways: through experiments and a summary of the facts will be knowledge and expertise into th

96、e form of vague rules, stored in the knowledge base, and with the corresponding Fuzzy neural network to optimize the fuzzy rules, the other is through on-site historical data on the fuzzy neural network reasoning machine

97、 training, access to non-deterministic knowledge, and through human-machine dialogue to complemen</p><p>　　IMIS, this paper mill AGC hydraulic system to take the diagnosis strategy:</p><p>　　1.

98、Object-oriented system in the previous strategy of the key components of the system's fault diagnosis on the basis of research, focus on monitoring the hydraulic system AGC function. Hydraulic energy on the part of t