• 대한기계학회논문집A
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• 제21권11호
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• pp.1862-1870
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• 1997

A fast and precise technique to measure 3-dimensional coordinates of an object is proposed. It is essential to take the 3-dimensional measurements of the object in design and inspection. Using this developed system a surface model of a complex shape can be constructed. 3-dimensional world coordinates are projected onto a camera plane by the perspective transformation, which plays an important role in this measurement system. According to the shape of the object two measuring methods are proposed. One is rotation of an object and the other is translation of measuring unit. Measuring speed depending on image processing time is obtained as 200 points per second. Measurement resolution i sexperimented by two parameters among others; the angle between the laser beam plane and the camera, and the distance between the camera and the object. As a result of these experiments, it was found that measurement resolution ranges from 0.3mm to 1.0mm. This constructed surface model could be used in manufacturing tools such as rapid prototyping machine.

• 대한기계학회논문집A
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• 제26권12호
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• pp.2687-2694
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• 2002

A precision displacement measuring system is proposed, which can detect the 3-DOF translational motions of precision positioning devices. The optical system, which is composed of two diode-laser sources and two quadratic PSDs, is adapted to detect the position of the spherical reflector usually mounted on the platform of positioning devices. Each of the laser beams from diode-laser sources is reflected at the highly reflective surface of the sphere; hence, the 3-dimensional position of the sphere causes the directional change of the reflected beams, which is detected by the PSDs. In this paper, we define the relationships between the output values of the two PSDs and the 3-DOF translational motions of the sphere. Based on a deduced measurement model, we perform measurement simulation and evaluate the performance of the proposed measurement system: linearity, sensitivity, measuring range, and measurement error. The results show that the proposed measuring method is very useful for the measurement of the precision displacement of 3-DOF micro motions.

• 한국정밀공학회지
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• 제18권11호
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• pp.51-57
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• 2001

A light beam reflected from a machined surface generally containes information concerning about its surface roughness. This study examines and proposes a surface roughness measurement technique for on-machine measurement of machined surfaces. The technique is based on the measurement of a reflected laser beam pattern and the statistical analysis of its light intensity distribution. The surface roughness was found to be closely related to the standard deviation of the light intensity on the primary axis of the reflected pattern. An image acquisition device is made up of a laser diode, a half mirror, a screen, and a CCD camera. The exact image with the primary and secondary axes of a reflected laser beam pattern is calculated through such image processing algorithm as thresholding, edge detection, image rotation, segmentation, etc. A median filter and a surrounding light correction algorithm are improve the image quality and reduce the measuring error. Using the developed measuring device the effect of screen materials and workpiece and workpiece materials was investigated. Experimental results regarding to relatively high-quality surfaces machined by grinding, polishing, lapping processes have shown the measurement error is within 10% in the range of $0.1{mu}m~0.8{\mu}m R_q.$Therefore, the proposed method is thought to be effectively used when quick measurements is needed with workpieces fixed on the machine.

• Nuclear Engineering and Technology
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• 제43권2호
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• pp.133-140
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• 2011

In this paper, a deformation measurement technology for nuclear fuel rods is proposed. The deformation measurement system includes a high-definition CMOS image sensor, a lens, a semiconductor laser line beam marker, and optical and mechanical accessories. The basic idea of the proposed deformation measurement system is to illuminate the outer surface of a fuel rod with a collimated laser line beam at an angle of 45 degrees or higher. For this method, it is assumed that a nuclear fuel rod and the optical axis of the image sensor for observing the rod are vertically composed. The relative motion of the fuel rod in the horizontal direction causes the illuminated laser line beam to move vertically along the surface of the fuel rod. The resulting change of the laser line beam position on the surface of the fuel rod is imaged as a parabolic beam in the high-definition CMOS image sensor. An ellipse model is then extracted from the parabolic beam pattern. The center coordinates of the ellipse model are taken as the feature of the deformed fuel rod. The vertical offset of the feature point of the nuclear fuel rod is derived based on the displacement of the offset in the horizontal direction. Based on the experimental results for a nuclear fuel rod sample with a formation of surface crud, an inspection resolution of 50 ${\mu}m$ is achieved using the proposed method. In terms of the degree of precision, this inspection resolution is an improvement of more than 300% from a 150 ${\mu}m$ resolution, which is the conventional measurement criteria required for the deformation of neutron irradiated fuel rods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.2945-2965
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• 2023

The laser inertial measurement unit is a precision device widely used in rocket navigation system and other equipment, and its quality is directly related to navigation accuracy. In the quality evaluation of laser inertial measurement unit, there is inevitably uncertainty in the index input information. First, the input numerical information is in interval form. Second, the index input grade and the quality evaluation result grade are given according to different national standards. So, it is a key step to transform the interval information input by the index into the data form consistent with the evaluation result grade. In the case of uncertain input, this paper puts forward a method based on probability distribution to solve the problem of asymmetry between the reference grade given by the index and the evaluation result grade when evaluating the quality of laser inertial measurement unit. By mapping the numerical relationship between the designated reference level and the evaluation reference level of the index information under different distributions, the index evidence symmetrical with the evaluation reference level is given. After the uncertain input information is transformed into evidence of interval degree distribution by this method, the information fusion of interval degree distribution evidence is carried out by interval evidential reasoning algorithm, and the evaluation result is obtained by projection covariance matrix adaptive evolution strategy optimization. Taking a five-meter redundant laser inertial measurement unit as an example, the applicability and effectiveness of this method are verified.

• 전자공학회논문지B
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• 제29B권2호
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• pp.27-39
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• 1992

3 Dimensional measurement system using camera and laser slit-ray is studied. Precise calibration technique in this system is suggested. Calibration is accomplished with calibration die, calibration block and robot. For obtaining calibration parameters, the equations are solved using least square error method from a great many calibration points to reduce measuring error. Continuous measurement is possible for the object which is larger than one frame of camera. The efficiency and usability are proved by applying to the tire profile measuring system which measures tire profile using robot and this system.

• 한국안전학회지
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• 제9권1호
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• pp.19-27
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• 1994

A laser-based in-process measurement system for the evaluation of surface roughness In turning Is reported. The proposed measuring system makes it possible to detect the surface roughness not only circumferential path but also along the feed direction even during machining. Also, it permits the real-time measurement of surface roughness In dynamic condition.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.821-823
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• 2003

산업 전반에 사용되는 수백W-수kW의 $CO_2$ 및 Nd:YAG 레이저광 출력측정 및 교정을 위해 정밀한 레이저 계측 장치를 제작하고 성능 평가 및 출력 측정을 위해 National Instrument사의 LabVIEW를 이용한 프로그램을 작성하였다. 레이저광의 출력측정을 위해 전원 공급기와 두 대의 DVM, 디지털 카운터를 GPIB를 통해 PC에 연결하였고 이를 이용해 데이터를 수집하여 그 결과를 분석하였다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2010년 춘계학술발표회 논문집
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• pp.307-308
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• 2010

The present research carried out displacement measurement and section & capacity measurement of a archcrown of a tunnel by using a laser scanner in underground tunnel excavation work that a bridge construction is being executed.

• Journal of the Optical Society of Korea
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• 제5권2호
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• pp.60-66
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• 2001

The authors discuss a prototype stylus profilometer designed to measure large optics. It consists of a low contact force type probe system, laser reference system, interferometric distance measurement system, and horizontal driving system. The probe contacts the surface ; the height and the horizontal distances of the measurement points are measured by the interferometer. The freely propagated laser beam provides the reference line during the measurement. The developed stylus profilometry shows only $\pm$60 nm of P-V error for the 157 mm diameter spherical mirror.