• 대한기계학회논문집A
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• 제21권9호
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• pp.1531-1540
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• 1997

Mordern industrial society pursues unmanned system and automation of manufacturing process. Abreast with this tendensy, production of goods which requires advanced accuracy is increasing as well. According to this, the work sensing time of dressing by monitoring and diagnosing the condition of grinding, which is th representative way in accurate manufacturing, is an important work to prevent serious damages which affect grinding process or products by wearing grinding wheel. Computer vision system was composed, so that grinding wheel surface was acquired by CCD camera and the change of cutting edge ratio was measured. Then we used automatic thresholding technique from histogram as a way of dividing grinding cutting edge from grinding surface. As a result, we are trying to approach unmanned system and automation by deciding more accurate time of dressing and by visualizing behavior of grinding wheel by making use of computer vision.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1846-1856
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• 2016

This study proposes a novel feature point initialization method in order to improve the accuracy of feature point positions by fusing a vision sensor and a lidar. The initialization is a process that determines three dimensional positions of feature points through two dimensional image data, which has a direct influence on performance of a 6-DoF bearing-only SLAM. Prior to the initialization, an extrinsic calibration method which estimates rotational and translational relationships between a vision sensor and lidar using multiple calibration tools was employed, then the feature point initialization method based on the estimated extrinsic calibration parameters was presented. In this process, in order to improve performance of the accuracy of the initialized feature points, an iterative automatic scaling parameter tuning technique was presented. The validity of the proposed feature point initialization method was verified in a 6-DoF bearing-only SLAM framework through an indoor and outdoor tests that compare estimation performance with the previous initialization method.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.154-154
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• 2017

Root is an important organ of plant that typically lies below the surface of the soil. Root surface determines the ability of plants to absorb nutrient and water from the surrounding soil. This study describes an application of image processing and computer vision which was implemented for rapid measurement of seed germination such as root length, surface area, average diameter, branching points of roots. A CCD camera was used to obtain RGB image of seed germination which have been planted by wet paper in a humidity chamber. Temperature was controlled at approximately 250C and 90% relative humidity. Pre-processing techniques such as color space, binarized image by customized threshold, removal noise, dilation, skeleton method were applied to the obtained images for root segmentation. The various morphological parameters of roots were estimated from a root skeleton image with the accuracy of 95% and the speed of within 10 seconds. These results demonstrated the high potential of computer vision technique for the measurement of seed germination.

• 한국지능시스템학회논문지
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• 제11권6호
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• pp.470-476
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• 2001

본 논문에서는 미지의 환경에서 동작하는 비전 시스템을 갖는 이동로봇의 경로 계획과 장애물 회피를 위한 새로운 알고리즘을 제안하고자 한다. 목표점에 도달하기 위한 경로계획과 장애물회피를 위해 거리 변화율 기법을 적용하였으며, 소벨연산자를 이용하여 장애물의 윤곽을 추출하였다. 이동로봇의 자율성을 향상시키기 위해 경로 설정과 장애물 회피에 퍼지 규직을 사용하였다. 본 논문에서 제안된 알고리즘을 컴퓨터시뮬레이션을 통해 기존의 벡터장 기법을 이용한것보다 우수하다는것을 알수 있었다. 또한 실효성을 실제로 알아보기 위해 소형 이동로봇을 제작하였으며, 제안된 알고리즘을 탑재하여 실험한 결과 복잡한 주변환경하에서도 좋은 성능을 발휘함을 확인할수 있었다.

• 한국항공우주학회지
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• 제41권7호
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• pp.532-538
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• 2013

본 논문은 편대비헹에서 영상만을 이용하여 선도기의 자세를 예측 하는 알고리즘 개발에 대해 논하고 있다. X-PLANE 시뮬레이터를 이용하여 획득한 영상에 SURF(Speed Up Robust Features)알고리즘을 이용하여 특징점을 추출 하였다. 그리고 자세예측 방법은 POSIT(Pose from Orthography and Scaling with Iteration) 알고리즘을 사용하였다. 결론적으로 우리는 영상만을 이용한 자세추정법이 $1.1{\sim}1.76^{\circ}$의 작은 추정오차 결과를 나타냄을 확인할 수 있었다.

• 한국정밀공학회지
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• 제14권12호
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• pp.17-23
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• 1997

A 3-D vision system is developed to evaluate blanks' line up and monitor gap and thickness difference between blanks in tailored blank welding system. A structured lighting method is used for 3-D vision recognition. Images of sheared portion in blanks are irregular according to roughness of blank surface, shape of sheared geometry and blurring. It is difficult to get accurate and reliable informations in the case of using binary image processing or contour detection techniques in real time for such images. We propoe a new energy integration method robust to blurring and changes of illumination. The method is computationally simple, and uses feature restoration concept, different to another digital image restoration methods which aim image itself restoration and may be used in conventional applications using structured line lighting technique. Experimental results show this system measuring repeatability is .+-. pixel for gap and thickness difference in static and dynamic tests. The data are expected to be useful for preview gap control.

• 한국구조물진단유지관리공학회 논문집
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• 제27권5호
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• pp.120-129
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• 2023

행어케이블의 장력은 현수교의 건전성과 안전성을 확인할 수 있는 주요 응답 중 하나이다. 일반적으로 공용 중인 현수교에서 행어케이블의 장력을 추정하기 위해 진동법이 주로 사용되고 있다. 진동법은 행어케이블에서 고유진동수들을 측정하고 행어케이블의 형상 조건을 이용하여 간접적으로 장력을 추정하는 방법이다. 이 연구에서는 영상계측시스템을 이용하여 팔영대교의 행어케이블에 대하여 장력을 추정하였다. 영상계측시스템은 측정의 편의성과 경제성을 고려하여 디지털 캠코더와 삼각대를 사용하였다. 영상계측시스템을 이용하여 측정된 행어케이블의 응답은 변위 기반이므로 진동법을 적용하기 위한 고차모드의 고유진동수는 측정하기 어려울 수 있다. 이 연구에서는 저차모드의 고유 진동수를 이용하여 장력을 추정할 수 있는 역해석 기법을 적용하였다. 역해석 기법은 현장에서 측정된 행어케이블의 고유진동수들과 유한요소해석을 이용하여 산정된 고유진동수들의 오차를 목적함수로 정의하여 최적화를 수행하였다. 최적화 방법은 목적함수의 편미분이 필요 없는 직접탐색법을 적용하였다. 역해석 기법을 이용하여 산정된 장력과 진동법을 이용하여 추정된 장력을 비교 분석하여 역해석 기법에 대한 신뢰도와 정확도를 확인하였다. 그 결과 역해석 기법을 적용하면 저차모드의 고유진동수를 이용하여도 신뢰성 있는 장력의 추정이 가능하였다.

• 센서학회지
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• 제11권5호
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• pp.255-262
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• 2002

인간의 망막은 효율적으로 주어진 물체의 윤곽을 검출할 수 있다. 본 연구에서는 윤곽검출에 관여하는 망막 세포의 기능을 전자회로로 모델링하여 윤곽검출기능을 가지는 CMOS 시각칩을 설계하였다. CMOS 제조공정 중에는 여러 가지 요인에 의해 MOSFET의 특성이 변화할 수 있으며, 특히 어레이로 구성되어 각 픽셀의 신호를 출력하는 readout 회로에서의 특성변화는 출력옵셋으로 나타난다. 하드웨어로 입력영상의 윤곽을 검출하는 시각칩은 다른 응용시스템의 입력단에 사용되므로 이러한 옵셋은 전체 시스템의 성능을 결정하는 중요한 요소이다. 본 연구에서는 이와 같은 출력단의 옵셋을 제거하기 위해 CDS(Correlated Double Sampling) 회로를 이용한 윤곽 검출용 시각칩을 설계하였다. 설계된 시각칩은 CMOS 표준공정을 이용하여 다른 회로와 집적화가 가능하며, 기존의 시각칩보다 신뢰성 있는 출력특성을 나타냄으로써, 물체의 윤곽을 이용하는 물체추적, 지문인식, 인간 친화적 로봇시스템등의 다양한 응용 시스템의 입력단으로 적용될 수 있을 것이다.

• 제어로봇시스템학회논문지
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• 제22권3호
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• pp.210-216
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• 2016

This paper presents a novel collision avoidance technique for mobile robots based on omni-directional vision simultaneous localization and mapping (SLAM). This method estimates the avoidance path and speed of a robot from the location of an obstacle, which can be detected using the Lucas-Kanade Optical Flow in images obtained through fish-eye cameras mounted on the robots. The conventional methods suggest avoidance paths by constructing an arbitrary force field around the obstacle found in the complete map obtained through the SLAM. Robots can also avoid obstacles by using the speed command based on the robot modeling and curved movement path of the robot. The recent research has been improved by optimizing the algorithm for the actual robot. However, research related to a robot using omni-directional vision SLAM to acquire around information at once has been comparatively less studied. The robot with the proposed algorithm avoids obstacles according to the estimated avoidance path based on the map obtained through an omni-directional vision SLAM using a fisheye image, and returns to the original path. In particular, it avoids the obstacles with various speed and direction using acceleration components based on motion information obtained by analyzing around the obstacles. The experimental results confirm the reliability of an avoidance algorithm through comparison between position obtained by the proposed algorithm and the real position collected while avoiding the obstacles.

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.65-76
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• 2003

The analysis of cow body parameters is important to provide some useful information fur cow management and cow evaluation. Present methods give many stresses to cows because they are invasive and constrain cow postures during measurement of body parameters. This study was conducted to develop the stereo vision system fur non-invasive analysis of cow body features. Body feature parameters of 16 heads at two farms(A, B) were measured using scales and nineteen stereo images of them with walking postures were captured under outdoor illumination. In this study, the camera calibration and inverse perspective transformation technique was established fer the stereo vision system. Two calibration results were presented for farm A and fm B, respectively because setup distances from camera to cow were 510 cm at farm A and 630cm at farm B. Calibration error values fer the stereo vision system were within 2 cm for farm A and less than 4.9 cm for farm B. Eleven feature points of cow body were extracted on stereo images interactively and five assistant points were determined by computer program. 3D world coordinates for these 15 points were calculated by computer program and also used for calculation of cow body parameters such as withers height. pelvic arch height. body length. slope body length. chest depth and chest width. Measured errors for body parameters were less than 10% for most cows. For a few cow. measured errors for slope body length and chest width were more than 10% due to searching errors fer their feature points at inside-body positions. Equation for chest girth estimated by chest depth and chest width was presented. Maximum of estimated error fur chest girth was within 10% of real values and mean value of estimated error was 8.2cm. The analysis of cow body parameters using stereo vision system were successful although body shape on the binocular stereo image was distorted due to cow movements.