• Journal of Welding and Joining
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• 제17권3호
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• pp.71-78
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• 1999

The welded metal bellows is commonly manufactured by welding pairs of washer-shaped discs of thin sheet metal stamped from strip stock in thickness from 0.025 to 0.254 mm. The discs, or diaphragms, are formed with mating circumferential corrugations. In this study, the diaphragms were welded by using a CW Nd: YAG laser to form metal bellows. The bellows was fixed on a jig and compressed axially, while Cu-rings were installed between belows edges for intimate contact of edges. The difference between the inner diameter of bellows and jig shaft causes an eccentricity, while the tolerance between motor shaft and jig shaft causes a wobble type motion. A vision sensor which is based on the optical triangulation was used for seam tracking. An image processing algorithm which can distinguish the image by bellows edge from that by Cu-ring was developed. The geometric relationship which describes the eccentricity and wobble type motion was modeled. The seam tracking using the image processing algorithm and the geometric modeling was performed successfully.

• 비파괴검사학회지
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• 제32권2호
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• pp.162-169
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• 2012

본 논문은 초음파 적외선 열화상과 위상잠금 방법을 이용하여 이종금속용접(STS304 and SA106 Gr. b)된 파이프의 응력부식균열 결함을 검출하였다. 초음파 가진장치는 출력 250 Watt, 주파수 20 kHz이었다. 실험 결과 이종금속용접부의 파이프 내부에 위치한 균열을 적외선 열화상을 이용하여 검출할 수 있었다. 실제 PT검사를 통하여 배관 내부의 균열이 하나가 아닌 일정한 범위 안에 하나 이상의 크랙이 존재하여 열화상 이미지 상에 넓은 범위의 hot spot 이미지를 만들어 냈음을 파악할 수 있었다. 또한 기존 기술로 검출이 용이하지 못한 마이크로 폭의 미세균열을 검출할 수 있었다. 또한, 초음파탐상기술은 $10\;{\mu}m$ 미세크랙의 폭을 갖은 균열을 쉽게 검출하지 못하였다. 그러나 초음파 적외선 열화상 기술은 결함 검출하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국제학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.446-450
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• 1993

In this paper we propose an arc welding robot system, where two robots works coordinately and employ the vision sensor. In this system one robot arm holds a welding target as a positioning device, and the other robot moves the welding torch. The vision sensor consists of two laser slit-ray projectors and one CCD TV camera, and is mounted on the top of one robot. The vision sensor detects the 3-dimensional shape of the groove on the target work which needs to be weld. And two robots are moved coordinately to trace the grooves with accuracy. In order to realize fast image processing, totally five sets of high-speed parallel processing units (Transputer) are employed. The teaching tasks of the coordinated motions are simplified considerably due to this vision sensor. Experimental results reveal the applicability of our system.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2017년도 춘계학술발표대회
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• pp.433-435
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• 2017

본 논문은 영상 장치를 이용한 자동화 시스템으로 용접 시 발생하는 용접 비드 정보 검출 방법에 대한 연구이다. 조명시스템과 결합된 2D 비전 카메라를 이용하여 용접된 시료 영상을 획득하고 영상처리과정을 거처 비드 부분만 획득한다. 획득된 비드 폭의 길이와 기공과 같이 용접 불량 상태 등의 정보 얻는다. 이 정보들과 산업체에서 요구되는 기준과 비교하여 정상적인 용접이 이루어 졌는지를 판별한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1299-1306
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• 2007

The combination of laser beam and electric arc sharing common weld pool has widely been investigated since the late seventies, but it is beginning of the industrial uses. Recently, laser-GMA hybrid welding process showed possibility to overcome the tight gap tolerance with improved productivity. The laser-arc hybrid welding process is inherently complex because it has three kinds of process parameters: arc welding, laser welding and hybrid welding parameters. In this study, the optimum range of the process parameters were determined by high speed image analysis which could unveil the welding phenomena in laser-arc hybrid welding. The laser-arc hybrid welding was applied for position welding from the flat position to the overhead position and the welding characteristics were investigated.

• 제어로봇시스템학회논문지
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• 제11권7호
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• pp.595-601
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• 2005

A mobile robot system utilizing NDT (Non-Destructive Testing) method is designed and fabricated f3r automatic integrity evaluation of large sized industrial reservoirs and pipelines. The developed mobile robot can crawl over the outer surface of the industrial facilities even though the shape of the structures is various and unsymmetric. The robot detects defects such as pinholes, cracks and thickness reduction at the wall of the facilities using EMAT (Electro-Magnetic Acoustic Transducer). Image processing technology for weld line detection at the surface of the target and host programs including defect detecting algorithms are also developed. Automation of defect detection for these kinds of large facilities using mobile robots is helpful to prevent significant troubles of the structures without danger of human beings under harmful environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1506-1511
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• 2003

This paper describes an automatic weld seam tracking method of plasma arc welding system designed for the corrugation panel that consists of a linear section and a curved section with various curvatures. Due to the complexity of the panel shape, it is difficult to find a seam and operate a torch manually in the welding process. So, the laser vision sensor for seam tracking is designed for sensing the seam position and controlling a torch automatically. To achieve precise seam tracking, the design of sensor head, image simulation, and calibration are carried out. Through a series of experiment result, compensation algorithm is added and real time error compensation is achieved. The experiment result shows that this vision sensor works effectively. It will provide more precise welding performance and convenience to the operator.

• 한국레이저가공학회지
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• 제13권2호
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• pp.17-23
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• 2010

It is very important to track a complicate weld seam for the welding automation. Very recently, laser vision sensor becomes a useful sensing tool to find the seams. Until now, however studies of welding automation using a laser vision sensor, focused on either image processing or feature recognition from CCD camera. Even though it is possible to use a simple algorithm for tracking a simple seam, it is extremely difficult to develop a seam-tracking algorithm when the seam is more complex. To overcome these difficulties, this study introduces a simulation system to develop the seam tracking algorithm. This method was verified experimentally to reduce the time and effort to develop the seam tracking algorithm, and to implement the sensing device.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.558-561
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• 2002

A CCD camera with a laser strip was applied to realize the automation of welding Process in GMAW. It takes relatively long time to process image on-line control using the basic Hough transformation, but it has a tendency of robustness over the noise such spatter and arc light. The adaptive Hough transformation was used to extract the laser stripe and to obtain specific weld points In this study, a neural network based on the generalized delta rule algorithm was adapted for the process control of GMA, such as welding speed, arc voltage and wire feeding speed.

• 융합신호처리학회논문지
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• 제23권4호
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• pp.241-248
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• 2022

SRD(Shear Reinforcement of Dual Anchorage)는 건축 현장에서 철근 콘크리트 구조물의 안전성을 보강하는 데 사용된다. 전단 보강재를 만들 때에는 용접이 사용되며, 용접은 제품의 생산성 및 경쟁력을 좌우하는 데 중요한 역할을 한다. 따라서 용접 비드 검출 검사가 필요하다. 본 연구에서는 용접 비드의 영상 자료를 이용하여 용접 비드를 검사하는 알고리즘을 제안한다. 제안한 알고리즘은 먼저 영상 내 수직 방향으로 밝깃값을 계산한 뒤, 밝깃값 분포의 50% 높이 지점에 해당하는 위치를 영상에서 찾아서 수직 방향으로 용접 비드를 분할한다. 그리고 수평 방향에 대해서도 동일한 방법으로 용접 비드 영역을 분할한 뒤, 분할 영상을 분석하여 용접비드 유무를 검사한다. 제안한 알고리즘은 관심 영역을 먼저 지정한 뒤 분석을 수행하여 연산량을 감소시켰다. 또한 SRD 영상에서 모재와 용접 비드 영역 사이에 밝깃값의 차이 특징을 이용하여 수직 및 수평 방향의 모든 밝깃값을 이용함으로써 정확도를 높일 수 있었다. 실험에서는 용접 비드 유무를 검출하기 위한 방법들로써 K-평균, k-최근접 이웃 등 5개의 알고리즘을 이용하여 분석 결과들을 비교하였으며, 타 알고리즘들에 비해 제안한 알고리즘의 정확도가 가장 높음을 보였다.