六足行走機器人設(shè)計,六足行走機器人設(shè)計,行走,機器人,設(shè)計 本本科科畢業(yè)論文文(設(shè)計)題目目審批批表表(教教師用用)學(xué)院：機械工程學(xué)院論文題目六足行走機器人設(shè)計指導(dǎo)教師姓名關(guān)浩職稱教授專業(yè)機械制造教研室名稱關(guān)浩答辯組是否首次指導(dǎo)畢業(yè)論文否擬需學(xué)生人數(shù)1近三年是否指導(dǎo)雷同題目否畢業(yè)論文類型工程設(shè)計型-理工類選題內(nèi)容提要一種新型的六足行走機器人設(shè)計及應(yīng)用研究（1）確定合理的設(shè)計方案。（2）對系統(tǒng)及機器人硬件組裝和調(diào)試（3）設(shè)計控制系統(tǒng)設(shè)計包括方案設(shè)計、基本參數(shù)計算、結(jié)構(gòu)設(shè)計、實物模型制作等選題的必要性隨著計算機，傳感，機電一體化技術(shù)的發(fā)展，機器人的智力和可靠性不斷提高，應(yīng)用范圍也不斷擴大。本課題就是利用仿生學(xué)原理研究機器人在許多高危險環(huán)境、野外勘察等場合應(yīng)用。主要是仿昆蟲的行走能力。選題的可行性本課題有許多類似的器械成功的設(shè)計為依據(jù)，有工作室多年的機械設(shè)計的前期工作為基礎(chǔ)，機械設(shè)計自動化的學(xué)生又有較好的知識與創(chuàng)新實踐的經(jīng)驗，因此理論與實際均可實現(xiàn)。審核意見系(教研室)主任意見學(xué)院教學(xué)指導(dǎo)委員會意見同意同意簽字：賈衛(wèi)平日期：2016-12-08簽字：賈衛(wèi)平日期：2016-12-08畢業(yè)論文類型：理工類畢業(yè)論文(設(shè)計)題目類型主要分為：1.工程設(shè)計型 2.科學(xué)實驗型 3.軟件開發(fā)型4.理論研究型 5.綜合型 6.其他；文科、管理類專業(yè)的論文題目類型主要分為：1.理論性論文 2.應(yīng)用性論文 3.應(yīng)用軟件設(shè)計 4.調(diào)查報告 5.其他 附錄A X射線實時影象探傷管道機器人的關(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器人系統(tǒng)，它被發(fā)展作為X射線實時圖象檢查法 [RTIIT]的自動化平臺。該機器人在管道內(nèi)可以獨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焊縫進行質(zhì)量檢驗的任務(wù)。該機器人系統(tǒng)安裝有一個小的焦點和具有定向波束的X射線管，因此可以獲得清晰度較高的焊接接縫圖像。關(guān)于該機器人系統(tǒng)個別的關(guān)鍵技術(shù)也將被詳細說明。它的結(jié)構(gòu)是（？） 。 關(guān)鍵詞：X射線探傷、實時影象、機器人 0 介紹 與射線照相檢查方法（RET）相比較，X射線實時圖像檢查法（RTIIT）有許多優(yōu)勢，比如較高的效率、較低的成本，更容易實現(xiàn)自動化和對焊接缺陷進行即時評估。此外，最新的技術(shù)允許X射線RTIIT被用在對管道進行無損檢測（NDT），并且這個方法的檢查品質(zhì)和RET[1，2]是一樣的。因此，無損檢測設(shè)備，通常用于管道檢驗的基于RET的設(shè)備，需要通過改造變成基于X射線實時圖像檢查法的。 使用X射線實時圖像檢查法對管道進行無損檢測一定要有一個自動化平臺，X射線探傷實時影象管道機器人（irtipr）就是為該目的而設(shè)計的。事實上，除了已經(jīng)被解決[３]的涉及X射線探傷實時影象管道機器人的問題之外，一些集中在機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，機器人在管道內(nèi)的獨立動作，同步控制技術(shù)和在管道內(nèi)外之間信息交流配合，我們也將機器人的結(jié)構(gòu)（ ？ ）。 1 機器人的工作原理 這個X射線探傷實時影象管道機器人由管道內(nèi)和管道外兩部分組成，結(jié)構(gòu)詳見圖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)機構(gòu)和它的驅(qū)動系統(tǒng)（11，12）組成。圖像擴大器由管道外旋轉(zhuǎn)機構(gòu)來推動并圍繞管道中心旋轉(zhuǎn)進行采集焊接圖像及通過圖像采集卡將圖象信號傳達給圖像處理計算機。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)動系統(tǒng)（３）、X射線系統(tǒng)（４）、管道內(nèi)同步旋轉(zhuǎn)機構(gòu)及其驅(qū)動系統(tǒng)（５,6）和焊接接縫獨立尋找及定位系統(tǒng)（７）。X射線系統(tǒng)中的X射線管由管道內(nèi)的旋轉(zhuǎn)機構(gòu)推動圍繞管道的中心旋轉(zhuǎn)。 圖1 X射線探傷實時影象管道機器人的結(jié)構(gòu) 機器人主要工作原理說明如下：在焊接接縫獨立尋找及定位系統(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)。當它收到從管道外由低頻電磁波傳達的指令信號時，管道內(nèi)的電腦立即操縱X射線系統(tǒng)的控制器來實現(xiàn)管道外的控制。管道內(nèi)和管道外的旋轉(zhuǎn)機構(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射線圖象標準檢查程序為基礎(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)的焊接接縫獨立尋找及定位技術(shù)。 2.1 管道內(nèi)和管道外旋轉(zhuǎn)機構(gòu)的同步控制技術(shù) 根據(jù) X射線實時圖象檢查法的技術(shù)要求，X射線管和圖像增強器必須圍繞同時地同一個中心旋轉(zhuǎn)。因為X射線irtipr采用無線的工作方式，機器人管道內(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)機構(gòu)的控制系統(tǒng)之間實現(xiàn)同步信息通信，或如何實現(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：當管道內(nèi)的旋轉(zhuǎn)機構(gòu)帶動X射線管到旋轉(zhuǎn)α角時，管道外的旋轉(zhuǎn)機構(gòu)也帶動圖像增強器同時繞同樣的中心旋轉(zhuǎn)到相同的角度（圖2）。因為金屬管道的遮擋作用和無線的特征，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射線探傷實時影象管道機器人的特殊性，我們提出這同步控制方案如下：將一個垂直于焊接接縫的標準檢查程序?qū)Ь€設(shè)置在X射線管的照射窗上；當 X射線照射到焊接接縫時，標準檢查程序?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)機構(gòu)處于同步的位置，即X射線管的照射窗和圖像增強器的軸是重合的（α=0）（圖2），標準檢查程序?qū)Ь€成像在電腦屏幕的中心位置。標準檢查程序?qū)Ь€的成像和標準檢查程序的中心線重合，看圖3。當管道內(nèi)旋轉(zhuǎn)機構(gòu)旋轉(zhuǎn)α角時，在屏幕上標準檢查程序?qū)Ь€的成像偏離標準檢查程序中心線，距離為H 。距離H被用作管道外旋轉(zhuǎn)機構(gòu)控制系統(tǒng)的錯誤輸入使調(diào)節(jié)自身旋轉(zhuǎn)運動直到這距離H為零或小于指定值，管道外旋轉(zhuǎn)機構(gòu)同步動作可以被實現(xiàn)。 試驗和模擬證明以上同步控制技術(shù)是正確的。這種同步動作滿足X射線探傷實時影象管道機器人的技術(shù)要求。 這種方法以 X射線當做觀測信號源，管道內(nèi)和管道外的旋轉(zhuǎn)機構(gòu)同步動作信息通過X射線圖象的標準檢查程序?qū)Ь€偏離標準檢查程序中心線距離確定，從而執(zhí)行同步動作.這種方法已經(jīng)申請發(fā)明專利。 圖2 同步旋轉(zhuǎn)機構(gòu) 圖3 X射線圖象的標準檢查程序?qū)Ь€ ⒉２焊接接縫的獨立尋找及定位技術(shù) 獨立尋找并定位意味著在管道內(nèi)機器人沒有任何其他干涉僅借助于傳感器自動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器人是否可以實現(xiàn)在管道內(nèi)獨立行動有直接關(guān)系。如果這個系統(tǒng)是無效的，機器人將在管道中“死亡”或“迷路”[6]。 大略地說，檢測焊接位置接縫方法如下：（1）利用編碼器或圓弧測定器；（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射線信號源）；（５）利用觀測；（６）利用低頻電磁波。 因為這種方法受許多因素的影響，例如：行進時剎車、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,即每個焊接接縫的間距大約12m,和各種位置檢測方法優(yōu)點和缺點,以多種成象設(shè)備為基礎(chǔ)的焊接接縫獨立尋找及定位系統(tǒng)被提出來改善和提高精確度、效率和可靠性的局限。多種成象設(shè)備由圓弧測定器、CCD攝像機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 焊接接縫獨立尋找并定位系統(tǒng) 系統(tǒng)采用定位反饋來提高定位的效率。反饋成像構(gòu)成的視覺反饋系統(tǒng)實現(xiàn)精確的定位。 合成數(shù)據(jù)以三種測量數(shù)據(jù)為基礎(chǔ)，圓弧測定器的數(shù)據(jù)、低頻電磁波以及圖象，使用優(yōu)先估計算法處理數(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表示圓弧測定器的測量數(shù)據(jù)，x2是低頻電磁波，x3是圖象。X表示機器人在管道的內(nèi)實際位置，各個焊接接縫的間距是12m。那么，三種測量數(shù)據(jù)的有效作用范圍如下：x∈[1 ,12m]；x2∈[0.1m ,1m]；x3 ∈[-10cm,10cm]，最后的定位目標是x3 = 0.三種測量數(shù)據(jù)有效范圍描述如下：當距離x1相距焊接接縫位置是大于100cm時，使用圓弧測定器是為了提高定位效率，并且機器人在管道內(nèi)以高速移動；當數(shù)據(jù)x2是小于100cm時，控制器變成低頻電磁波，并且讓機器人以低速度移動；當焊接接縫進入這圖象范圍時，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。定位精確度的測試結(jié)果在≤±3毫米內(nèi)，可以滿足這設(shè)計要求。 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—關(guān)信號。考慮它的危險，X射線系統(tǒng)經(jīng)從管道外遙控操縱。因為這機器人是無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—關(guān)信號的任務(wù)。所以低頻電磁波被采用來發(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實現(xiàn)自動化。如果一個機器人采用沒有電纜的工作方式且它的管道內(nèi)外旋轉(zhuǎn)機構(gòu)同步控制技術(shù)沒有被解決，它根本不可能為X射線rtiit實現(xiàn)自動化。焊接接縫獨立尋找及定位技術(shù)是有形的具體化的智能機器人，也保證了機器人工作的高可靠性。低頻電磁波實現(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.因為這機器人安裝有一小的焦點以及定向波束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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