• 제어로봇시스템학회논문지
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• 제16권1호
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• pp.18-24
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• 2010

In this paper, we address an active ranging system based on laser structured light image for mobile robot application. Since the burdensome correspondence problem is avoidable, the structured light image processing has efficient computation in comparison with the conventional stereo image processing. By using a cylindrical lens in the laser generation, it is possible to convert a point laser into a stripe laser without motorized scan in the proposed system. In order to achieve robustness against environmental illumination noise, we propose an efficient integro-differential image processing algorithm. The proposed system has embedded image processing module and transmits distance data to reduce the computational burden in main control system.

• 한국레이저가공학회지
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• 제12권2호
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• pp.11-16
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• 2009

A new profile measurement sensor was developed for remote laser welding robots. A stripe laser and a vision camera are used in the profile sensor. A simple sensor guided control scheme using the developed sensor is also introduced. The sensor can be used to guide the welding head in the remote welding application, where the working distance reaches to 450mm. In experiments, the profile measurement and the seam tracking were carried out using the developed sensor.

• 전자공학회논문지CI
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• 제42권1호
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• pp.51-58
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• 2005

레이저 스트라이프 신호를 물체에 투사하고 그 반사파형을 비전 카메라를 통하여 입력하면 물체의 입체적 정보를 갖는 파형이 나타나게 된다. 이를 활용하여 물체의 3차인 입체정보를 저장하고 활용하고 있는 상황이다. 본 연구는 사람에 대해 적은 수의 스트라이프 신호를 투사하고 반사된 입체적 스트라이프 파형을 분석하였으며 사람에 대한 특징적 패턴 파형을 추출하고 푸리에 서술자를 이용하여 이러한 패턴을 분류 저장하였다. Baum-Welch 알고리즘을 통하여 저장된 특징 파형을 학습시키고 HMM을 이용하여 사람의 형상에 대한 스트라이프 신호를 컴퓨터에 입력하고 사람의 형상을 인식할 수 있는 지를 실험하였으며 푸리에 서술자를 통한 인식방법과 비교하였다. 실험을 통해서 특정 파형으로 학습 후 인체의 형상을 인식할 수 있음을 확인하였으며, HMM을 통한 인식방법이 우수함을 알 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.652-657
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• 1991

Up to date, application areas of mobile robots have been expanded. In addition, Many types of LRF(Laser Range Finder) systems have been developed to acquire three dimensional information about unknown environments. However in real world, because of various noises (sunlight, fluorescent light), it is difficult to separate reflected laser light from these noise. To overcome the previous restriction, we have developed a new type vision system which enables a mobile robot to measure the distance to a object located 1-5 (m) ahead with an error than 2%. The separation and detection algorithm used in this system consists of pulse phase difference method and multi-stripe structured light. The effectiveness and feasibility of the proposed vision system are demonstrated by 3-D maps of detected objects and computation time analysis.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.20-20
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• 2003

We developed 30 ㎽-AlInGaN based violet laser diodes. The fabrication procedures of the laser diodes are described as follows. Firstly, GaN layers having very low defect density were grown on sapphire substrates by lateral epitaxial overgrowth method. The typical dislocation density was about 1-3$\times$10$^{6}$ /$\textrm{cm}^2$ at the wing region. Secondly, AlInGaN laser structures were grown on LEO-GaN/sapphire substrates by MOCVD. UV activation method, instead of conventional annealing, was conducted to achieve good p-type conduction. Thirdly, ridge stripe laser structures were fabricated. The cavity mirrors were formed by cleaving method. Three pairs of SiO$_2$ and TiO$_2$ layers were deposited on the rear facet for mirror coating. Lastly, laser diode chips were mounted on AlN submount wafers by epi-down bonding method. The lifetime of the laser diodes was over 10,000 hrs at room temperature under automatic power controlled condition. We expect the performance of the LDs to be improved by the optimization of the growth and fabrication process. The detailed characteristics and important issues of the laser diodes will be discussed at the conference.