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畢業(yè)論文(設(shè)計(jì))任務(wù)書(shū) 論文(設(shè)計(jì))題目：六足行走機(jī)器人設(shè)計(jì) 工作日期：2016年12月12日 ~ 2017年05月26日 1.選題依據(jù): 本課題是為社會(huì)服務(wù)而研究的一個(gè)實(shí)際課題。是一個(gè)新型實(shí)用機(jī)械設(shè)計(jì)，同時(shí)又是為學(xué)生參加創(chuàng)新設(shè)計(jì)大賽準(zhǔn)備的作品。 2.論文要求(設(shè)計(jì)參數(shù)): （1）根據(jù)實(shí)際應(yīng)用情況，做詳細(xì)的調(diào)研，并在此基礎(chǔ)上確定合理的方案。（2）方案要求實(shí)現(xiàn)六足行走機(jī)器人設(shè)計(jì)要求。 （3）制定系統(tǒng)總體設(shè)計(jì)方案，繪制系統(tǒng)的設(shè)計(jì)圖。（4）對(duì)系統(tǒng)進(jìn)行必要的參數(shù)計(jì)算。 （5）完成對(duì)系統(tǒng)的控制設(shè)計(jì)工作（6）編寫(xiě)設(shè)計(jì)說(shuō)明書(shū)一份。 3.個(gè)人工作重點(diǎn): 本課題的重點(diǎn)是六足行走機(jī)器人的結(jié)構(gòu)設(shè)計(jì)，根據(jù)實(shí)際要求，研究六足行走機(jī)器人的特點(diǎn)及運(yùn)動(dòng)規(guī)律，設(shè)計(jì)合理的機(jī)械結(jié)構(gòu)。 4.時(shí)間安排及應(yīng)完成的工作: 第1周：布置題目，討論題目，進(jìn)行課題調(diào)研第2周：在深入理解課題的基礎(chǔ)上進(jìn)行課題調(diào)研第3周：繼續(xù)討論課題，研討開(kāi)題報(bào)告的撰寫(xiě)第4周：撰寫(xiě)開(kāi)報(bào)告，進(jìn)行開(kāi)題報(bào)告答辯 第5周：在充分調(diào)研的基礎(chǔ)上進(jìn)行方案論證及設(shè)計(jì)。 第6周：繼續(xù)討論課題的總體方案，并就具體細(xì)節(jié)分別進(jìn)行論證。第7周：進(jìn)行六足行走機(jī)器人的結(jié)構(gòu)設(shè)計(jì)，繪制總體方案圖。 第8周：進(jìn)行必要的計(jì)算，確定六足行走機(jī)器人結(jié)構(gòu)方案的合理性。第9周：進(jìn)行六足行走機(jī)器人的各部分的結(jié)構(gòu)設(shè)計(jì)，進(jìn)行部件設(shè)計(jì)第10周：繼續(xù)完善各部件設(shè)計(jì)及進(jìn)行個(gè)別零件的設(shè)計(jì)。 第11周：討論六足行走機(jī)器人控制系統(tǒng)的設(shè)計(jì)方案，確定合理的設(shè)計(jì)方案。第12周：進(jìn)行控制系統(tǒng)設(shè)計(jì)，確定控制系統(tǒng)的最佳方案第13周：繼續(xù)進(jìn)行控制系統(tǒng)設(shè)計(jì)，完善控制系統(tǒng)細(xì)節(jié) 第14周：進(jìn)行六足行走機(jī)器人分析與研討，進(jìn)行結(jié)構(gòu)和控制系統(tǒng)的修改第15周：完善設(shè)計(jì)圖紙及說(shuō)明書(shū)的修改工作。 第16周：整理設(shè)計(jì)說(shuō)明書(shū)及答辯資料，準(zhǔn)備答辯第17周：畢業(yè)設(shè)計(jì)答辯 5.應(yīng)閱讀的基本文獻(xiàn): [1]韓建海 趙書(shū)尚 李濟(jì)順 《六足機(jī)器人行走步態(tài)的協(xié)調(diào)控制》 機(jī)電工程 2004年 第21卷第4期[2]鄭忠楷 《智能避障機(jī)器人設(shè)計(jì)初探》 福州師專(zhuān)學(xué)報(bào) 2002年4月 第22卷 第2期 [3]張澤榮 王學(xué)彬 《可編程序控制器原理與應(yīng)用》 清華大學(xué)出版社北京交通大學(xué)出版社2004年[4]熊有倫 《機(jī)器人技術(shù)基礎(chǔ)》 華中科技大學(xué)出版社 1995年 [5]李磊 葉濤 譚民 陳細(xì)軍 《移動(dòng)機(jī)器人技術(shù)研究現(xiàn)狀與未來(lái)》 機(jī)器人 2002年9月 第24卷第5期[6]顧勇平 周華平 馬宏緒 《多足機(jī)器人群控策略及可靠性問(wèn)題》 機(jī)器人 2002年3月 第24卷 第2期 [7]李貽斌 《現(xiàn)代科技革命與機(jī)器人的發(fā)展》 山東交通學(xué)院學(xué)報(bào) 2002年12月 第10卷 第4期 [8] 楊東超 趙明國(guó) 陳懇 王永輝 《機(jī)器人一般自由度計(jì)算公式的統(tǒng)一認(rèn)識(shí)》 專(zhuān)題論文 2002年8月 [9]葛運(yùn)建 張建軍 戈瑜 吳仲城 高理富 《無(wú)所不在的傳感與機(jī)器人感知》 自動(dòng)化學(xué) 報(bào) 2002年12月 第28卷 增刊 [10]榮宏 《可編程控制器梯形圖編程應(yīng)用技巧》 成都紡織高等專(zhuān)科學(xué)校學(xué)報(bào) 2002年7月第19卷 第3期[11]楊波 鄧偉珍 《ＰＬＣ系統(tǒng)的抗干擾措施》 長(zhǎng)春理工大學(xué)學(xué)報(bào) 2002年9月 第25卷 第3期 [12]梅燕民 彭光正 范偉 《氣動(dòng)爬墻機(jī)器人》 液壓氣動(dòng)與密封 2002年2月 第1期[13]靳平 《可編程控制器系統(tǒng)的故障分析》 江蘇技術(shù)師范學(xué)院學(xué)報(bào) 2002年12月 第８卷第４期 附錄A X射線實(shí)時(shí)影象探傷管道機(jī)器人的關(guān)鍵技術(shù) 摘要 這篇論文介紹了一種檢查大口徑管道焊接連接的機(jī)器人系統(tǒng)，它被發(fā)展作為X射線實(shí)時(shí)圖象檢查法 [RTIIT]的自動(dòng)化平臺(tái)。該機(jī)器人在管道內(nèi)可以獨(dú)立尋找并確定焊接接縫位置，在同步控制技術(shù)的控制下可以完成對(duì)焊縫進(jìn)行質(zhì)量檢驗(yàn)的任務(wù)。該機(jī)器人系統(tǒng)安裝有一個(gè)小的焦點(diǎn)和具有定向波束的X射線管，因此可以獲得清晰度較高的焊接接縫圖像。關(guān)于該機(jī)器人系統(tǒng)個(gè)別的關(guān)鍵技術(shù)也將被詳細(xì)說(shuō)明。它的結(jié)構(gòu)是（？） 。 關(guān)鍵詞：X射線探傷、實(shí)時(shí)影象、機(jī)器人 0 介紹 與射線照相檢查方法（RET）相比較，X射線實(shí)時(shí)圖像檢查法（RTIIT）有許多優(yōu)勢(shì)，比如較高的效率、較低的成本，更容易實(shí)現(xiàn)自動(dòng)化和對(duì)焊接缺陷進(jìn)行即時(shí)評(píng)估。此外，最新的技術(shù)允許X射線RTIIT被用在對(duì)管道進(jìn)行無(wú)損檢測(cè)（NDT），并且這個(gè)方法的檢查品質(zhì)和RET[1，2]是一樣的。因此，無(wú)損檢測(cè)設(shè)備，通常用于管道檢驗(yàn)的基于RET的設(shè)備，需要通過(guò)改造變成基于X射線實(shí)時(shí)圖像檢查法的。 使用X射線實(shí)時(shí)圖像檢查法對(duì)管道進(jìn)行無(wú)損檢測(cè)一定要有一個(gè)自動(dòng)化平臺(tái)，X射線探傷實(shí)時(shí)影象管道機(jī)器人（irtipr）就是為該目的而設(shè)計(jì)的。事實(shí)上，除了已經(jīng)被解決[３]的涉及X射線探傷實(shí)時(shí)影象管道機(jī)器人的問(wèn)題之外，一些集中在機(jī)器人的智能控制的關(guān)鍵技術(shù)也出現(xiàn)在這篇論文中。，例如，機(jī)器人在管道內(nèi)的獨(dú)立動(dòng)作，同步控制技術(shù)和在管道內(nèi)外之間信息交流配合，我們也將機(jī)器人的結(jié)構(gòu)（ ？ ）。 1 機(jī)器人的工作原理 這個(gè)X射線探傷實(shí)時(shí)影象管道機(jī)器人由管道內(nèi)和管道外兩部分組成，結(jié)構(gòu)詳見(jiàn)圖1。管道外的部分由圖像采集處理系統(tǒng)（8，9，10），管道外同步旋轉(zhuǎn)機(jī)構(gòu)和它的驅(qū)動(dòng)系統(tǒng)（11，12）組成。圖像擴(kuò)大器由管道外旋轉(zhuǎn)機(jī)構(gòu)來(lái)推動(dòng)并圍繞管道中心旋轉(zhuǎn)進(jìn)行采集焊接圖像及通過(guò)圖像采集卡將圖象信號(hào)傳達(dá)給圖像處理計(jì)算機(jī)。管道內(nèi)的部分由管道內(nèi)電腦（1）、電源和換流器系統(tǒng)（２）、行走及其驅(qū)動(dòng)系統(tǒng)（３）、X射線系統(tǒng)（４）、管道內(nèi)同步旋轉(zhuǎn)機(jī)構(gòu)及其驅(qū)動(dòng)系統(tǒng)（５,6）和焊接接縫獨(dú)立尋找及定位系統(tǒng)（７）。X射線系統(tǒng)中的X射線管由管道內(nèi)的旋轉(zhuǎn)機(jī)構(gòu)推動(dòng)圍繞管道的中心旋轉(zhuǎn)。 圖1 X射線探傷實(shí)時(shí)影象管道機(jī)器人的結(jié)構(gòu) 機(jī)器人主要工作原理說(shuō)明如下：在焊接接縫獨(dú)立尋找及定位系統(tǒng)的控制下管內(nèi)爬行器完成工作位置的定位，并在定位的位置上處于等待的狀態(tài)。當(dāng)它收到從管道外由低頻電磁波傳達(dá)的指令信號(hào)時(shí)，管道內(nèi)的電腦立即操縱X射線系統(tǒng)的控制器來(lái)實(shí)現(xiàn)管道外的控制。管道內(nèi)和管道外的旋轉(zhuǎn)機(jī)構(gòu)由同步控制技術(shù)控制圍繞相同的管道中心旋轉(zhuǎn)并按旋轉(zhuǎn)-照射-旋轉(zhuǎn)的方式完成焊接接縫檢查。 ２ 機(jī)器人的控制系統(tǒng) 與工藝步驟的工作原理相比，X射線irtipr的控制系統(tǒng)主要由一些關(guān)鍵技術(shù)組成，例如以X射線圖象標(biāo)準(zhǔn)檢查程序?yàn)榛A(chǔ)的同步控制技術(shù)和以數(shù)據(jù)合成及低頻電磁波傳遞為基礎(chǔ)的焊接接縫獨(dú)立尋找及定位技術(shù)。 2.1 管道內(nèi)和管道外旋轉(zhuǎn)機(jī)構(gòu)的同步控制技術(shù) 根據(jù) X射線實(shí)時(shí)圖象檢查法的技術(shù)要求，X射線管和圖像增強(qiáng)器必須圍繞同時(shí)地同一個(gè)中心旋轉(zhuǎn)。因?yàn)閄射線irtipr采用無(wú)線的工作方式，機(jī)器人管道內(nèi)同管道外的部分是不可能的由電纜連接著的。如何在管道內(nèi)外旋轉(zhuǎn)機(jī)構(gòu)的控制系統(tǒng)之間實(shí)現(xiàn)同步信息通信，或如何實(shí)現(xiàn)同步控制，變成必須被解決的關(guān)鍵技術(shù)。 同步旋轉(zhuǎn)可以被描述為：當(dāng)管道內(nèi)的旋轉(zhuǎn)機(jī)構(gòu)帶動(dòng)X射線管到旋轉(zhuǎn)α角時(shí)，管道外的旋轉(zhuǎn)機(jī)構(gòu)也帶動(dòng)圖像增強(qiáng)器同時(shí)繞同樣的中心旋轉(zhuǎn)到相同的角度（圖2）。因?yàn)榻饘俟艿赖恼趽踝饔煤蜔o(wú)線的特征，現(xiàn)有的通信手段很難完成在管道內(nèi)外控制信息的通信（４,5）。根據(jù)X射線探傷實(shí)時(shí)影象管道機(jī)器人的特殊性，我們提出這同步控制方案如下：將一個(gè)垂直于焊接接縫的標(biāo)準(zhǔn)檢查程序?qū)Ь€設(shè)置在X射線管的照射窗上；當(dāng) X射線照射到焊接接縫時(shí)，標(biāo)準(zhǔn)檢查程序?qū)Ь€也在管道外的電腦上成像。只要管道內(nèi)和管道外旋轉(zhuǎn)機(jī)構(gòu)處于同步的位置，即X射線管的照射窗和圖像增強(qiáng)器的軸是重合的（α=0）（圖2），標(biāo)準(zhǔn)檢查程序?qū)Ь€成像在電腦屏幕的中心位置。標(biāo)準(zhǔn)檢查程序?qū)Ь€的成像和標(biāo)準(zhǔn)檢查程序的中心線重合，看圖3。當(dāng)管道內(nèi)旋轉(zhuǎn)機(jī)構(gòu)旋轉(zhuǎn)α角時(shí)，在屏幕上標(biāo)準(zhǔn)檢查程序?qū)Ь€的成像偏離標(biāo)準(zhǔn)檢查程序中心線，距離為H 。距離H被用作管道外旋轉(zhuǎn)機(jī)構(gòu)控制系統(tǒng)的錯(cuò)誤輸入使調(diào)節(jié)自身旋轉(zhuǎn)運(yùn)動(dòng)直到這距離H為零或小于指定值，管道外旋轉(zhuǎn)機(jī)構(gòu)同步動(dòng)作可以被實(shí)現(xiàn)。 試驗(yàn)和模擬證明以上同步控制技術(shù)是正確的。這種同步動(dòng)作滿足X射線探傷實(shí)時(shí)影象管道機(jī)器人的技術(shù)要求。 這種方法以 X射線當(dāng)做觀測(cè)信號(hào)源，管道內(nèi)和管道外的旋轉(zhuǎn)機(jī)構(gòu)同步動(dòng)作信息通過(guò)X射線圖象的標(biāo)準(zhǔn)檢查程序?qū)Ь€偏離標(biāo)準(zhǔn)檢查程序中心線距離確定，從而執(zhí)行同步動(dòng)作.這種方法已經(jīng)申請(qǐng)發(fā)明專(zhuān)利。 圖2 同步旋轉(zhuǎn)機(jī)構(gòu) 圖3 X射線圖象的標(biāo)準(zhǔn)檢查程序?qū)Ь€ ⒉２焊接接縫的獨(dú)立尋找及定位技術(shù) 獨(dú)立尋找并定位意味著在管道內(nèi)機(jī)器人沒(méi)有任何其他干涉僅借助于傳感器自動(dòng)地決定哪里是工作位置.這種控制方式就是“智能控制”。尋找及定位系統(tǒng)的精確度和可靠性與機(jī)器人是否可以實(shí)現(xiàn)在管道內(nèi)獨(dú)立行動(dòng)有直接關(guān)系。如果這個(gè)系統(tǒng)是無(wú)效的，機(jī)器人將在管道中“死亡”或“迷路”[6]。 大略地說(shuō)，檢測(cè)焊接位置接縫方法如下：（1）利用編碼器或圓弧測(cè)定器；（２）利用焊接接縫表面伸出凹面變化的位移所引起位移；（３）利用焊縫表面接縫導(dǎo)電；（４）利用放射性同位素（比如γ射線信號(hào)源）；（５）利用觀測(cè)；（６）利用低頻電磁波。 因?yàn)檫@種方法受許多因素的影響，例如：行進(jìn)時(shí)剎車(chē)、管道內(nèi)的環(huán)境、人為的因素、放射性的傷害、定位的精確度和效率，僅僅使用一種方法是不能獲得滿意效果的。 考慮到焊接接縫的規(guī)則排列,即每個(gè)焊接接縫的間距大約12m,和各種位置檢測(cè)方法優(yōu)點(diǎn)和缺點(diǎn),以多種成象設(shè)備為基礎(chǔ)的焊接接縫獨(dú)立尋找及定位系統(tǒng)被提出來(lái)改善和提高精確度、效率和可靠性的局限。多種成象設(shè)備由圓弧測(cè)定器、CCD攝像機(jī)和低頻電磁波的接收器和發(fā)射極組成。系統(tǒng)的框圖如圖4。 圖4 焊接接縫獨(dú)立尋找并定位系統(tǒng) 系統(tǒng)采用定位反饋來(lái)提高定位的效率。反饋成像構(gòu)成的視覺(jué)反饋系統(tǒng)實(shí)現(xiàn)精確的定位。 合成數(shù)據(jù)以三種測(cè)量數(shù)據(jù)為基礎(chǔ)，圓弧測(cè)定器的數(shù)據(jù)、低頻電磁波以及圖象，使用優(yōu)先估計(jì)算法處理數(shù)據(jù)。根據(jù)三種定位法的特征，上述數(shù)據(jù)在不同的范圍分別地有效。如果x1表示圓弧測(cè)定器的測(cè)量數(shù)據(jù)，x2是低頻電磁波，x3是圖象。X表示機(jī)器人在管道的內(nèi)實(shí)際位置，各個(gè)焊接接縫的間距是12m。那么，三種測(cè)量數(shù)據(jù)的有效作用范圍如下：x∈[1 ,12m]；x2∈[0.1m ,1m]；x3 ∈[-10cm,10cm]，最后的定位目標(biāo)是x3 = 0.三種測(cè)量數(shù)據(jù)有效范圍描述如下：當(dāng)距離x1相距焊接接縫位置是大于100cm時(shí)，使用圓弧測(cè)定器是為了提高定位效率，并且機(jī)器人在管道內(nèi)以高速移動(dòng)；當(dāng)數(shù)據(jù)x2是小于100cm時(shí)，控制器變成低頻電磁波，并且讓機(jī)器人以低速度移動(dòng)；當(dāng)焊接接縫進(jìn)入這圖象范圍時(shí)，采用圖象伺服系統(tǒng)獲得精確的定位。 數(shù)據(jù)合成規(guī)律可以表示為：X = X1 如果（x3 > - 10）且（x3 < 10），那么X =x3；以上方法實(shí)現(xiàn)了模糊控制并且完美地解決了精確度以及定位效率之間的矛盾。定位精確度的測(cè)試結(jié)果在≤±3毫米內(nèi)，可以滿足這設(shè)計(jì)要求。 ⒉３低頻電磁波的傳遞 除了定位的作用，低頻電磁波還被利用于傳送管道內(nèi)外部分之間的開(kāi)—關(guān)信號(hào)?？紤]它的危險(xiǎn)，X射線系統(tǒng)經(jīng)從管道外遙控操縱。因?yàn)檫@機(jī)器人是無(wú)線的以及考慮到金屬管道的遮擋作用，其他的方法不能完成管道內(nèi)外部分之間傳送開(kāi)—關(guān)信號(hào)的任務(wù)。所以低頻電磁波被采用來(lái)發(fā)送操作命令到管道內(nèi)控制x射線系統(tǒng)。 3 結(jié)論 這X射線irtipr的關(guān)鍵技術(shù)是保證為X射線rtiit實(shí)現(xiàn)自動(dòng)化。如果一個(gè)機(jī)器人采用沒(méi)有電纜的工作方式且它的管道內(nèi)外旋轉(zhuǎn)機(jī)構(gòu)同步控制技術(shù)沒(méi)有被解決，它根本不可能為X射線rtiit實(shí)現(xiàn)自動(dòng)化。焊接接縫獨(dú)立尋找及定位技術(shù)是有形的具體化的智能機(jī)器人，也保證了機(jī)器人工作的高可靠性。低頻電磁波實(shí)現(xiàn)了管道內(nèi)外部分控制系統(tǒng)之間在金屬管道遮擋條件下的信息交流，并且起到了閉環(huán)的控制系統(tǒng)的作用。以這些關(guān)鍵技術(shù)為基礎(chǔ)的X射線irtipr可被用于對(duì)這大口徑管道（在660～1400mm）的檢查，工作距離大約2km，工作速度在18m / min.因?yàn)檫@機(jī)器人安裝有一小的焦點(diǎn)以及定向波束X射線管，與其它X射線管相比可以獲得較高的清晰度的焊接接縫圖像。這些關(guān)鍵技術(shù)在測(cè)試中被證明是完美地滿足了X射線rtiit的技術(shù)要求。 附錄B Key Techniques of the X2ray Inspection Real-timeImaging Pipeline Robot This paper presents a robotic system for weld-joint inspection of the big-caliber pipeline , which is developed for the purpose of being utilized as automation platform for X-ray real-time imaging inspection technique (RTIIT) . The robot can perform autonomous seeking and locating of weld-seam position in-pipe , and under the control of synchro-follow control technique it can accomplish the technologic task of weld inspection. The robotic system is equipped with a small focal spot and directional beam X-ray tube ,so the higher definition image of weld-seam can be obtained.Several key techniques about the robotic system developed are also explained in detail . Its construction is outlined. Key words : X-ray inspection ； real-time imaging ； robot 0 　Introduction Compared with radiographic examination technique(RET) , X-ray real time imaging inspection technique(RTIIT) has many advantages such as higher efficiency ,lower cost , better feasible automation and weld-defects evaluation on-line. Furthermore , up to date technology allows the X-ray RTIIT to be used in Non-Destructive Testing (NDT) of pipelines , and the inspection quality of this Technique is as good as that of the RET[1 ,2 ] . Therefore ,NDT equipments , which are used commonly in pipeline inspection and basing on the RET , need to be renovated by basing on the X-ray RTIIT. To employ the X-ray RTIIT in NDT of pipeline there must be an automation platform , and X-ray inspection real-time imaging pipeline robot ( IRTIPR) is designed for the purpose. In fact , besides the problems that have been resolved[3 ] and are involved in the X-ray IRTIPR , several key techniques are presented in this paper , in which we address the robot focusing on its intelligent control, i . e.the autonomous motion in-pipe , the synchro-follow controltechnique and the communication of cooperation between in-pipe and out-pipe , and we also outline the construction of the robot . 1 　Composing and Working Principle of the Robot The X-ray IRTIPR consists of the two parts of in-pipe and out-pipe , as illustrated in Figl 1. The out-pipe part is composed of image collecting and processing system (8 ,9 ,10) , out-pipe synchro-rotary mechanism and its driving system (11 ,12) . The image intensifier is driven by the out-pipe rotary mechanism to rotate round the center of pipeline to collect weld image and transmit video signal to image processing computer by image-collecting card. The in-pipe part is composed of in-pipe computer (1) , power and inverters system (2) , walking and driving system (3) , X-ray system (4) , in-pipe synchro-rotary mechanism and its driving system (5 ,6) and weld-seam autonomous seeking and locating system (7) . The X-ray tube in X-ray system is driven by the in-pipe rotary mechanism to rotate round the center of pipeline. Fig.1 The structure of X-ray IRTIPR The main working principle of the robot is explained as follows : Under the control of weld-seam autonomous seeking and locating system the in-pipe crawler finishes the localization of working position , at which the in-pipe crawler is in a state of waiting. When it receives the command signal from out-pipe , which is transmitted by low frequency electromagnetic wave , the in-pipe computer operates immediately the controller of X-ray system to realize its out-pipe control . In sequence the in-pipe and out-piperotary mechanisms are controlled by the synchro-followcontrol technique to rotate with the same center of pipeline and finish weld-seam inspection in the manner of rotating-irradiating-rotating. 2 　The Control System of the Robot According to the technologic process of working principle , the control system of X-ray IRTIPR is proposed and mainly made up of several key techniques such as the synchro-follow control technique based on the X-ray image of benchmark lead wire , the weld-seam autonomous seeking and locating technique based on data fusion and the communication of low frequency electromagnetic wave. 2. 1 　The Synchro-follow Control Technique of In-pipe and Out-pipe Rotary Mechanism In the light of the technologic requirement of X-ray RTIIT , the X-ray tube and the image intensifier must be required to rotate synchronously with the same center. Because the X-ray IRTIPR adopts wireless working manner , i . e. there is no tether cables linking in-pipe with out-pipe parts of the robot . How to realize the synchro-message communication between in-pipe and out-pipe control systems of rotary mechanism , or how to realize synchro-control , then becomes a key technique that must be solved. The synchro-follow rotating can be described as : when the in-pipe rotary mechanism drives X-ray tube to rotate an angle of α, the out-pipe rotary mechanism drives image intensifier to rotate the same angle synchronously with the same center too (Fig12) . Because of the shielding function of metal pipeline and wireless feature , the means of communication existed is difficult to accomplish control-message communication between in-pipe and out-pipe parts[4 ,5 ] . According to the particularity of X-ray IRTIPR , we put forward the synchro-control scheme as follows : a benchmark lead wire perpendicular to weld-seam is placed on the irradiation window of X-ray tube ; when the weld-seam is irradiated by X-ray , the benchmark lead wire is also imaged in out-pipe computer. As long as the in-pipe and out-pipe rotary mechanisms are in a synchronous position , namely the axis of irradiation window of X-ray tube is coincident with that of image intensifier (α= 0) (Fig12) , the image of benchmark lead wire is in the middle position of computer’s screen , i . e. the image of benchmark lead wire is coincident with the position of benchmark center-line ( H = 0) , see Fig13. When in-pipe rotary mechanism rotates an angle of α, the image of benchmark lead wire will deviate from benchmark center line on the screen , the distance is H. Then the distance H is used as an error input of control system of out-pipe rotary mechanism to regulate its rotating motion. Until the distance H is zero or smaller than appointed value , the synchro-follow motion of out-pipe rotary mechanism can be realized. The test and simulation prove that the above-mentioned synchro-follow control technique is correct . The synchro-motion satisfies the technologic requirement of X-ray RTIIT. The method utilizes X-ray as vision source , and the synchro-motion message of in-pipe and out-pipe rotary mechanisms is transmitted by the screen’s distance that the X-ray image of benchmark lead wire deviates from the benchmark center line , thus the synchro-motion is performed. The method has been applied for invention patent . Fig12 　The synchro2rotary mechanism Fig13 　The X2ray image of benchmark lead wire 2. 2 　Weld-seam Autonomous Seeking and Locating Technique Autonomous seeking and locating mean that the robot determines automatically where is the working position in-pipe with the help of sensors but without any one’s inter-meddling. This control-manner is actually“intelligent”. The precision and reliability of seeking and locating a system have direct relation with if a robot can realize autonomous motion in-pipe. If this system is disabled , the robot will take the place of the accident of“death”or“l(fā)ose the way”in-pipe[6 ] . Generally , methods for detecting the position of weld-seam are as follows : (1) Utilize encoder or cyclometer ; (2) Utilize the displacement caused by the protrusion-concave changing of weld-seam surface ; (3) Utilize if the zone of weld-seam conducts electricity ; (4) Utilize radioactive isotope ( such as γ ray source) ; (5) Utilize vision ; (6) Utilize low frequency electromagnetic wave. Because these methods are influenced by many factors such as walking wheel’s skid , the in-pipe environment , manmade factors , radioactive injury , locating precision and efficiency , satisfactory result can’t be obtained when one of the methods is used alone. Considering weld-seam regular array , i . e. the space between each weld-seam is about 12m , and advantages and disadvantages of each position-detection method , one system of weld-seam autonomous seeking and locating based on multi-sensors is put forward to improve and enhance the precision , efficiency and reliability of localization. Multi-sensors consist of the cyclometer , CCD camera and the receiver and emitter of low frequency electromagnetic wave. Systematic block diagram is depicted as Fig14. Fig14 　Weld-seam autonomous seeking and locating system The system adopts position feedback for enhancing the efficiency of localization. Vision servo is structured with image given feedback for realizing accurate localization. The data fusion based on three kinds of measure-data , which are the data of cyclometer , low frequency electromagnetic wave and vision , adopts the estimate-algorithm with priority to process data. In terms of the characteristics of three localization methods , the above data have different effective function region respectively. If X1 represents the measure-data of cyclometer , X2 of low frequency electromagnetic wave , X3 of vision. X represents the actual position in-pipe of the robot , the space between each weld-seam is 12m. Then , the effective function regions of three kinds of measure-data are as follows respectively : X1 ∈[ 1m ,12m] ; X2 ∈[ 0. 1m ,1m] ; X3 ∈[ -10cm ,10cm ] , the final localization goal is X3 = 0. The data fusion’s rule of three kinds of measure-data is described as : when the distance X1 away from weld-seam position is greater than 100cm , the cyclometer is employed for localization in order to enhance the efficiency , and let the in-pipe crawler move at a high speed ; when the data X2 is smaller than 100cm , the“attention”of the controller changes into the method of low frequency electromagnetic wave , and let the in-pipe crawler move at alow speed ; when the weld-seam enters the vision range , the vision servo is adopted for accurate localization. 　The data fusion’s rules are expressed as : X = X1 　　 if ( X3 > - 10) and ( X3 < 10) , then X = X3 ; The above-mentioned method that is realized with fuzzy control and datafusion has perfectly solved the contradiction between the precision and the efficiency of localization. The test result of localization precision is within ≤±3 mm , which can meet the design requirement . 2.3 The Communication of Low Frequency Electromagnetic Wave Besides the function of localization , low frequency electromagnetic wave is still utilized to transmit the off-on signal between in-pipe and out-pipe parts. Considering its dangers , the X-ray system is often operated with remote control from out-pipe. Because the robot is wireless and in view of the shielding function of metal pipeline , other methods cannot accomplish the mission that transmits the off-on signal between in-pipe and out-pipe parts. So the low frequency electromagnetic wave is adopted to transmit operation command for in-pipe computer to control the X-ray system. 3 　Conclusion Key techniques of the X-ray IRTIPR are assurances for X-ray RTIIT to realize automation. If a robot adopts the working means of having no cable and the synchro-follow control technique of in-pipe and out-pipe rotary mechanisms being not solved , it will be impossible for the X-ray RTIIT to realize automation at all . The weld-seam autonomous seeking and locating technique is a concrete embodiment of“intelligence”for the robot , and is also an assurance for the robot to work with high reliability. Low frequency electromagnetic wave realizes communication between a control system’s in-pipe and out-pipe parts under the condition of metal pipe’s shielding , and plays the role of closed loop of control system. The X-ray IRTIPR based on these key techniques can be used in the inspection of the big-caliber pipeline ( at ? 660 ～? 1400mm) , whose working distance is about 2km without charging and working speed is at 18m/ min. Because the robot is equipped with a small focal spot and directional beam X-ray tube , an image of weld-seam with higher definition can be obtained compared with other kinds of X-ray tube.These key techniques are proved in test and meet perfectly the technologic requirements of X-ray RTIIT. References [1 ] Zeng X Z, Sun Z C. Nondestructive Testing , 2001 , 12(12) : 530 [2 ] Zheng S C. Nondestructive Testing , 2000 , 22(7) : 328 [3 ] Jiang S Y. Research on in2pipe X2ray inspection robot technol2 ogy and theory : [ dissertation ] . Harbin : Harbin Institute of Technology , 2001 [4 ] Blettner A , Chauveau D , Becker. Robot for computerized real time radiographic inspection of on shore pipe welds. In : 6th European Conference on NonDestructive Testing. Nice , France : 1994. 225 [5 ] Anon. Welding in the world , 1990 , 28(5) :77 [6 ] Bjorkholm P J , Parker R , Johnson M. Design and application of a digital radiographic weld inspection system. 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