• 대한기계학회논문집A
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• 제29권6호
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• pp.795-803
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• 2005

This paper studies the observability of calibration system with a measurement operator. The calibration system needs a simple digital indicator to measure the mobile table movements with respect to the MC coordinate. However, it yields the concern about the poor parameter observability due to measuring only a part of the movements. We uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of an observation matrix. The number of identifiable parameter is examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a 6-axis MC with parallel tilting table and the calibration results are presented. These results verify that all necessary kinematic parameters are observable and the calibration system has robustness to the noise using optimal calibration configurations.

• 대한기계학회논문집A
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• 제27권4호
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• pp.647-655
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• 2003

This paper studies the observability of calibration system with a constraint movement by a constraint operator. The calibration system with the constraint movement need only simple sensing device to check whether the constraint movements are completed within an established range. However, it yields the concern about the poor parameter observability due to the constraint movements. This paper uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of a observation matrix. The number of identifiable parameters are examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a parallel typed machining center and the calibration results are presented. These results verify that the calibration system with low-cost indicators and simple planar table is accurate as well as reliable.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1512-1517
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• 2003

This paper presents the calibration for the parallel typed tilting table. The calibration system needs only simple sensing device which is a digital indicator to measure the orientation of a table. The calibration algorithm is developed by a measurement operator. It eliminates the concern about the poor parameter observability due to a large number of parameters of parallel-mechanism. This paper uses the QR-decomposition to find the optimal calibration configurations maximizing the linear independence of rows of a observation matrix. The number of identifiable parameters is examined by the rank of the observation matrix, which represents the parameter observability. The method is applied to a Parallel-typed Tilting Table and all the necessary kinematic parameters are identifiable.

• Journal of the Optical Society of Korea
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• 제18권6호
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• pp.746-752
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• 2014

In a multi-camera measurement system, the determination of the external parameters is one of the vital tasks, referred to as the calibration of the system. In this paper, a new geometrical calibration method, which is based on the theory of the vanishing line, is proposed. Using a planar target with three equally spaced parallel lines, the normal vector of the target plane can be confirmed easily in every camera coordinate system of the measurement system. By moving the target into more than two different positions, the rotation matrix can be determined from related theory, i.e., the expression of the same vector in different coordinate systems. Moreover, the translation matrix can be derived from the known distance between the adjacent parallel lines. In this paper, the main factors effecting the calibration are analyzed. Simulations show that the proposed method achieves robustness and accuracy. Experimental results show that the calibration can reach 1.25 mm with the range about 0.5m. Furthermore, this calibration method also can be used for auto-calibration of the multi-camera mefasurement system as the feature of parallels exists widely.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1886-1893
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• 2003

This paper examines the parameter observability of a calibration system that consrains a mobile platform to a planar table to take the calibration data. To improve the parameter observability, we find the optimal configurations providing the calibration with maximum contribution. The QR-decomposition is used to compute the optimal configurations that maximize the linear independence of rows of an observation matrix. The calibration system is applied to the parallel type manipulator constructed for a machining center. The calibration results show that all the necessary kinematic parameters assigned in a Stewart-Gough platform are identifiable and convergent to desirable accuracy.

• 한국전자파학회논문지
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• 제29권7호
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• pp.491-499
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• 2018

잡음지수분석기의 일반적인 교정방법은 잡음전원을 이용하는 방법이다. 이 방법은 교정 시 잡음전원과 잡음지수분석기의 부정합을 고려하지 않기 때문에 측정결과에서 심각한 불규칙 리플을 동반한다. 본 논문에서는 잡음전원과 잡음지수분석기의 부정합을 모두 고려한 새로운 잡음지수분석기의 교정 및 이를 이용한 새로운 잡음상관행렬 측정방법을 제안한다. 제안하는 방법은 uncorrected 잡음전력을 이용, 교정하지 않은 잡음지수분석기의 이득과 잡음상관행렬을 결정하였다. 그리고 결정된 이득과 잡음상관행렬을 이용, DUT에 대한 잡음상관행렬 측정결과에서 잡음지수분석기의 영향을 교정하였다. 제안된 방법을 통해, 측정된 DUT의 잡음파라미터는 상대적인 잡음비를 이용한 측정 결과와 같은 정도의 불규칙 리플을 보였다.

• 센서학회지
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• 제28권3호
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• pp.182-186
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• 2019

When a camera is employed for 3D sensing, accurate camera calibration is vital as it is a prerequisite for the subsequent steps of the sensing process. Camera calibration is usually performed by complex mathematical modeling and geometric analysis. On the other contrary, data learning using an artificial neural network can establish a transformation relation between the 3D space and the 2D camera image without explicit camera modeling. However, a neural network requires a large amount of accurate data for its learning. A significantly large amount of time and work using a precise system setup is needed to collect extensive data accurately in practice. In this study, we propose a two-step neural calibration method that is effective when only a small amount of learning data is available. In the first step, the camera projection transformation matrix is determined using the limited available data. In the second step, the transformation matrix is used for generating a large amount of synthetic data, and the neural network is trained using the generated data. Results of simulation study have shown that the proposed method as valid and effective.

• 대한전자공학회논문지SP
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• 제45권1호
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• pp.38-46
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• 2008

중요영상 선택 알고리즘은 다수의 비교정 영상으로부터 3차원 재구성을 위해 필수 영상을 선택하는 과정이다. 또한 3차원 재구성을 위해 영상들 사이의 카메라 자동교정(auto-calibration)이 필수적이다. 본 논문은 재구성 오차를 최대한 줄이는 최적의 영상을 선택하는 중요영상 선택 알고리즘을 제안한다. 선택된 중요영상들 사이의 카메라 투영행렬은 카메라 전자동교정(full-auto-calibration)과정을 통하여 추정한다. 정확하게 추정된 카메라 투영행렬로부터 대수학적 유도를 이용하여 기본행렬(fundamental matrix)을 계산하고, 이로부터 잘못된 대응점들을 제거하여 최종적으로 3차원 데이터를 얻는다. 실험 결과는 제안한 중요영상 선택 알고리즘이 다른 알고리즘에 비해 적은 시간이 소요되며, 재구성된 3차원 데이터의 오차가 가장 작았다. 대수학적 유도로부터 얻어낸 기본행렬은 다른 알고리즘에 비해 매우 짧은 시간이 소요 되며 평균 오차는 비슷한 결과를 갖는다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.387-393
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• 2004

General purpose of cylindrical capacitive displacement sensor(CCS) is measuring run-out motion and deflection of rotor. If CCS has narrow sensing range, its sensitivity coefficients must be calibrated precisely. And x, y component of CCS output can be coupled. In this research, CCS calibration procedure is automated with automatic calibration program and PC-controlled stage. And, coupled-terms of CCS signals were removed and the errors between measured position and mapped CCS signal were reduced obviously by sensitivity matrix that linearly.

• Mass Spectrometry Letters
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• 제9권3호
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• pp.77-80
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• 2018

The focus of this paper is to present techniques to overcome certain difficulties in quantitative analysis with a time-of-flight mass spectrometer (TOF-MS). The method is based on conventional solid-phase extraction, followed by reversed-phase ultra high performance liquid chromatography of the extract, and mass spectrometric analysis. The target compounds included atenolol, atrazine, caffeine, carbamazepine, diclofenac, estrone, ibuprofen, naproxen, simazine, sucralose, sulfamethoxazole, and triclosan. The matrix effects caused by high concentrations of organic compounds in wastewater are especially significant in electrospray ionization mass spectroscopy. Internal-standard calibration with isotopically labeled standards corrects the results for many matrix effects, but some peculiarities were observed. The problems encountered in quantitation of carbamazepine and triclosan, due to nonlinear calibration were solved by changing the internal standard and using a narrower mass window. With simazine, the use of a quadratic calibration curve was the best solution.