• 한국정밀공학회지
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• 제21권7호
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• pp.83-91
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• 2004

The determination of camera position and orientation from known correspondences of 3D reference points and their images is known as pose estimation in computer vision or space resection in photogrammetry. This paper discusses estimation of transform parameters using the pattern matching method with 2D images only. In general, the 3D reference points or lines are needed to find out the 3D transform parameters, but this method is applied without the 3D reference points or lines. It uses only two images to find out the transform parameters between two image. The algorithm is simulated using Visual C＋＋ on Windows 98.

• 센서학회지
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• 제25권3호
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• pp.202-207
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• 2016

Estimation of vertical position is critical in applications of sports science and fall detection and also controls of unmanned aerial vehicles and motor boats. Due to low accuracy of GPS(global positioning system) in the vertical direction, the integration of IMU(inertial measurement unit) with the GPS is not suitable for the vertical position estimation. This paper investigates an IMU-barometer integration for estimation of vertical position (as well as vertical velocity). In particular, a new two-step Kalman/complementary filter is proposed for accurate and efficient estimation using 6-axis IMU and barometer signals. The two-step filter is composed of (i) a Kalman filter that estimates vertical acceleration via tilt orientation of the sensor using the IMU signals and (ii) a complementary filter that estimates vertical position using the barometer signal and the vertical acceleration from the first step. The estimation performance was evaluated against a reference optical motion capture system. In the experimental results, the averaged estimation error of the proposed method was 19.7 cm while that of the raw barometer signal was 43.4 cm.

• ETRI Journal
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• 제37권4호
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• pp.766-771
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• 2015

Robust motion estimation for human-computer interactions played an important role in a novel method of interaction with electronic devices. Existing pose estimation using a monocular camera employs either ego-motion or exo-motion, both of which are not sufficiently accurate for estimating fine motion due to the motion ambiguity of rotation and translation. This paper presents a hybrid vision-based pose estimation method for fine-motion estimation that is specifically capable of extracting human body motion accurately. The method uses an ego-camera attached to a point of interest and exo-cameras located in the immediate surroundings of the point of interest. The exo-cameras can easily track the exact position of the point of interest by triangulation. Once the position is given, the ego-camera can accurately obtain the point of interest's orientation. In this way, any ambiguity between rotation and translation is eliminated and the exact motion of a target point (that is, ego-camera) can then be obtained. The proposed method is expected to provide a practical solution for robustly estimating fine motion in a non-contact manner, such as in interactive games that are designed for special purposes (for example, remote rehabilitation care systems).

• 한국사회복지학
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• 제61권1호
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• pp.5-32
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• 2009

본 연구는 장애인복지기관의 '조직문화'(합리문화, 개발문화, 집단문화, 위계문화)와 고객중심을 강조하는 '시장지향성', 그리고 조직성과지표로서의 '지역사회중심 사회통합지향성'(Community-Centered Social Inclusion Orientation [COSI])의 관계를 검증하기 위한 것이다. 이를 위해 COSI에 대한 4개 조직문화유형의 직접효과와 시장지향성을 매개로 한 간접효과를 설정한 연구 모형을 구성하여 이 모형 의 유용성을 경험적으로 규명하였다. 전국조사에서 얻어진 263개소 장애인복지기관의 응답내용이 구조방정식 모형을 통해 분석되었다. 분석결과, 시장지향성은 종속변수인 조직성과지표로서의 COSI에 유의한 영향을 주는 것으로 밝혀졌다. 조직문화와 관련해서는 개발문화와 위계문화적 속성이 종속변수에 직접효과를, 합리문화와 집단문화적 속성은 시장지향성을 통하여 간접효과를 가지는 것으로 나타났다. 획일적 조직문화 유형보다는 각 문화유형의 균형적 발달이 중요함을 시사하며, 조직성과를 위해 고객중심 그리고 부서 간 협력을 강조하는 시장지향성의 강화가 필요함을 확인할 수 있다.

• 한국정밀공학회지
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• 제16권12호
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• pp.87-98
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• 1999

This study is concentrated on the development of real-time estimation model and vision control method as well as the experimental test. The proposed method permits a kind of adaptability not otherwise available in that the relationship between the camera-space location of manipulable visual cues and the vector of manipulator joint coordinates is estimate in real time. This is done based on a estimation model ta\hat generalizes known manipulator kinematics to accommodate unknown relative camera position and orientation as well as uncertainty of manipulator. This vision control method is roboust and reliable, which overcomes the difficulties of the conventional research such as precise calibration of the vision sensor, exact kinematic modeling of the manipulator, and correct knowledge of position and orientation of CCD camera with respect to the manipulator base. Finally, evidence of the ability of real-time vision control method for manipulator's position control is provided by performing the thin-rod placement in space with 2 cues test model which is completed without a prior knowledge of camera or manipulator positions. This feature opens the door to a range of applications of manipulation, including a mobile manipulator with stationary cameras tracking and providing information for control of the manipulator event.

• 센서학회지
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• 제26권4호
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• pp.259-265
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• 2017

Magnetometer calibration must be performed before the use of three-axis magnetometers to ensure the accuracy of orientation estimation. Recently, one of the most popular calibration approaches is the ellipsoid fitting technique due to its high performance in calibration. To date, in fact, performances of the existing ellipsoid fitting methods have been evaluated with full range rotation data. However, in case of the calibration of magnetometers attached to vehicles, ships, and planes, it is very difficult to collect the full range rotation data since their allowable ranges in terms of roll and pitch are limited to small. This constraint may result in serious performance degradation of some ellipsoid fitting algorithms. Therefore, to be practical, this paper proposes a weighted least square-based magnetometer calibration method that is robust in roll-pitch limited conditions. Furthermore, the proposed method is a linear approach and thus is free from the well-known initial value issue in nonlinear approaches. Experimental results show the superiority of the proposed method to other ellipsoid-fitting calibration methods.

• 센서학회지
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• 제29권4호
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• pp.237-242
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• 2020

This paper deals with relative position estimation using a Kalman filter (KF) based on inertial sensors that have been widely used in various biomechanics-related outdoor applications. In previous studies, the relative position is determined using relative orientation and predetermined segment-to-joint (S2J) vectors, which are assumed to be constant. However, because body segments are influenced by soft tissue artifacts (STAs), including the deformation and sliding of the skin over the underlying bone structures, they are not constant, resulting in significant errors during relative position estimation. In this study, relative position estimation was performed using a KF, where the S2J vectors were adopted as time-varying states. The joint constraint and the variations of the S2J vectors were used to develop a measurement model of the proposed KF. Accordingly, the covariance matrix corresponding to the variations of the S2J vectors continuously changed within the ranges of the STA-causing flexion angles. The experimental results of the knee flexion tests showed that the proposed KF decreased the estimation errors in the longitudinal and lateral directions by 8.86 and 17.89 mm, respectively, compared with a conventional approach based on the application of constant S2J vectors.

• 천문학회보
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• 제37권2호
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• pp.159.2-159.2
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• 2012

In this study, we propose an effective strategy for precise orbital and geodetic parameter estimation using SLR (Satellite Laser Ranging) observations for ILRS AAC (Associate Analysis Center). The NASA/GSFC GEODYN II software and SLR normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 are utilized for precise orbital and geodetic parameter estimation. Weekly-based precise orbit determination strategy is applied to process SLR observations, and Precise Orbit Ephemeris (POE), TRF (Terrestrial Reference Frame), and EOPs (Earth Orientation Parameters) are obtained as products of ILRS AAC. For improved estimation results, selection strategies of dynamic and measurement models are experimently figured out and configurations of various estimation parameters are also carefully chosen. The results of orbit accuracy assessment of POE and precision analysis of TRF/EOPs for each case are compared with those of existing results. Finally, we find an appropriate strategy for precise orbital and geodetic parameter estimation using SLR observations for ILRS AAC.

• 한국측량학회지
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• 제37권6호
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• pp.465-472
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• 2019

사진 촬영 당시의 외부표정요소 추정 방법에는 공선조건식 기반 후방교회법이 널리 사용되지만 초기값을 필요로 하고, 그 값에 민감하다는 단점이 있다. 본 연구에서는 초기값을 필요로 하지 않는 외부표정요소 알고리즘인 쿼터니언 기반 공간후방교회법과 PnP (Perspective-n-Point algorithm)을 소개하고 그 결과를 비교하였다. 두 결과를 비교하기 위하여 일반 스마트폰으로 취득한 영상을 사용하였고, 지상기준점 취득은 본 연구진이 보유하고 있는 하이브리드 MMS (Mobile Mapping System) 점군 자료를 이용하였다. 그 결과, 공선조건식 기반 SPR (Single Photo Resection)을 참값으로 할 때, 쿼터니언 기반 SPR이 PnP 알고리즘에 비해 자세각 추정 정확도가 높았다. 카메라 위치추정의 경우에는 두 알고리즘 모두 지상기준점과 비교했을 때 0.8m 내의 정확도를 보임을 확인하였다.

• 한국측량학회지
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• 제23권2호
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• pp.137-145
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• 2005

이 논문에서는 선형 푸시브룸 방식으로 촬영한 위성영상에 대한 다양한 센서모델들의 정확도를 비교분석하고자 한다. 특히 이 논문에서는 센서모델의 정확도를 번들조정의 정확도와 외부표정요소추정의 정확도로 분리하여 고찰하려고 한다. 번들조정 정확도는 수립된 센서모델이 얼마나 기준점에 잘 부합하는 가를 알려주는 척도로 이제까지 대부분의 센서모델 정확도 분석에 사용되어온 기준이다. 이에 반하여 외부표정요소추정의 정확도는 센서모델이 얼마나 정확하게 촬영당시의 위성의 궤도 및 자세를 예측할 수 있는 지의 척도로서 매우 중요한 요소임에도 불구하고 기존의 연구에서 간과해온 부분이다. 이 논문에서는 여러 센서모델 중에서 사진측량분야에서 주로 사용하는 변형된 공선방정식기반 모델과 위성지상국 또는 자세제어분야에서 주로 사용하는 궤도좌표계 및 자세각에 기반한 모델의 정확도를 비교분석하고자 한다. 실험은 다목적실용위성 1호 EOC 영상과 GPS 수신기에서 취득한 기준점을 사용하였다. 실험결과 번들조정 정확도는 두 모델이 큰 차이를 보이지 않는 것으로 나타났으나 외부표정요소추정 정확도는 궤도좌표계 및 자세각에 기반한 모델이 더 나은 성능을 보였다.