• ETRI Journal
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• 제39권2호
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• pp.264-274
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• 2017

Recently, mobile positioning enhancement has attracted much attention in the 3rd generation partnership project long-term evolution system. In particular, for urban canyon environments, the need for three-dimensional (3D) positioning has increased to enable the altitude of users to be measured. For several decades, several time difference of arrival (TDOA-) based 3D positioning methods have been studied; however, they are only available when at least four evolved Node Bs (eNBs) exist nearby or when all eNBs have the same height. Therefore, in this paper, we propose a new 3D positioning method that estimates the 3D coordinates of a user using three types of two-dimensional (2D) TDOAs. However, the give inaccurate results owing to the undefined axis of the 2D coordinate plane. Therefore, we propose a novel derivation of the hyperbola equation, which includes the undefined axis coordinate in the 2D hyperbola equation. Then, we propose an interaction algorithm that mutually supplies the undefined axis coordinate of users among 2D TDOAs. By performing extensive simulations, we verify that the proposed method is the only solution applicable by using three eNBs with different heights.

• Journal of Positioning, Navigation, and Timing
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• 제7권2호
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• pp.61-71
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• 2018

Existing radio positioning systems have a drawback that the attitude of user's tag is difficult to be determined. Although forward link angle of arrival (FLAOA) technology that uses measurements of array antenna arranged in a tag among the angle of arrival (AOA) technologies can estimate attitude and positioning of tags, it cannot extend the estimated results into three-dimensional (3D) results due to complex non-linear model displayed because of the effects of 3D positioning and attitude in tags. This paper proposed a radio navigation technique that determines 3D attitude and positioning via FLAOA / time of arrival (TOA) integration. According to the order of determining attitude and positioning, two integration techniques were proposed. To analyze the performance of the proposed technique, MATLAB-based simulations were used to verify the performance. The simulation results showed that the first proposed method, TOA-FLAOA integrated technique, showed about 0.15 m of positioning error, and $2-3^{\circ}$ of attitude error performances regardless of the positioning space size whereas the second method, differenced FLAOA-TOA integrated technique, revealed a problem that a positioning error became larger as the size of the positioning space became larger.

• 동력기계공학회지
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• 제17권5호
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• pp.100-111
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• 2013

Indoor real-time positioning for multiple targets is required to realize human-robot symbiosis. This study firstly presents positioning accuracy on an autonomous mobile robot controlled by 3-D coordinates that is obtained by a real-time indoor positioning system with spread spectrum (SS) ultrasonic signals communicated by code-division multiple access. Although many positioning systems have been investigated, the positioning system with the SS ultrasonic signals can measure identified multiple 3-D positions in every 70 ms with noise tolerance and error within 100 mm. This system is also robust to occlusion and environmental changes. However, thus far, the positioning errors in an autonomous mobile robot, controlled by these systems using the SS ultrasonic signals, have not been evaluated as an experimental study. Therefore, a positioning experiment for trajectory control is conducted using an autonomous mobile robot and our positioning system. The effectiveness of this positioning method for robot self-localization is shown, from this experiment, because the average control error between the target position and the robot's position at 29 mm is obtained.

• 로봇학회논문지
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• 제11권3호
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• pp.172-182
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• 2016

Lane-level vehicle positioning is an important task for enhancing the accuracy of in-vehicle navigation systems and the safety of autonomous vehicles. GPS (Global Positioning System) and DGPS (Differential GPS) are generally used in navigation service systems, which however only provide an accuracy level up to 2~3 m. In this paper, we propose a 3D vision based lane-level positioning technique which can provides accurate vehicle position. The proposed method determines the current driving lane of a vehicle by tracking the 3D position of traffic signs which stand at the side of the road. Using a stereo camera, the 3D tracking paths of traffic signs are computed and their projections to the 2D road plane are used to determine the distance from the vehicle to the signs. Several experiments are performed to analyze the feasibility of the proposed method in many real roads. According to the experimental results, the proposed method can achieve 90.9% accuracy in lane-level positioning.

• Journal of Positioning, Navigation, and Timing
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• 제12권2호
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• pp.141-148
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• 2023

In this paper, impacts of tropospheric delay gradient correction on PPP positioning performance were analyzed. A correction for tropospheric delay error due to the gradient was created and applied using external data, and reference station data were collected on a sunny day and a rainy day to analyze the GPS only dual-frequency PPP positioning results. As a result, on the sunny day, the convergence time was about 35 minutes and the final 3D position error was 10 cm, regardless of whether the correction for the tropospheric delay error by the gradient was applied. On the other hand, on the rainy day, the 3D position error converges only when the correction was applied, and the convergence time was about 34 minutes. Furthermore, the final 3D position error was improved from 30 cm to 10 cm. In addition, the analysis of the PPP by reference station location on the rainy day showed that the PPP positioning performance was improved when the correction was applied to a user located in an area where the weather changes.

• 한국측량학회지
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• 제27권1호
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• pp.743-750
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• 2009

1972년 국내에서는 아날로그카메라를 이용하여 항공사진측량을 시작한 이래로 최근에는 항공사진측량의 효율성을 향상시키기 위해서 고해상도 디지털항공사진 카메라의 도입이 적극적으로 추진되고 있다. 본 연구에서는 항공사진측량을 위해 개발된 고해상도 디지털항공사진카메라 중에서 DMC(Digital Mapping Camera) 카메라에 대한 3차원 위치결정의 정확도를 기존의 아날로그카메라와 비교하여 평가하였다. 이를 위해서 인천인근지역에 테스트필드를 선정하고 기준점을 설치한 후 항공사진측량을 수행하였다. 아날로그카메라 및 DMC 카메라 항공사진의 3차원 위치결정의 정확도를 비교한 결과, 정확도에는 큰 차이가 없었으며, GPS/IMU 자료에 기준점을 추가하여 항공삼각측량을 수행한 후 위치결정을 수행했을 경우 정확도가 향상됨을 알 수 있었다.

• 한국통신학회논문지
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• 제38C권12호
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• pp.1126-1133
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• 2013

사용자 맞춤형의 지능화 서비스를 위해 실내에서 사용자 및 기기들의 3차원 위치를 인식하는 기술에 대한 중요성이 급증하고 있다. 본 논문에서는 최근 들어 폭발적으로 활성화된 스마트폰에서 음향신호를 발생하고 5개의 마이크들을 십자 형태로 동일 평면상에 배치한 3차원 위치 측정 장치에서 TDOA 방식을 적용하여 스마트폰의 3차원 위치 좌표를 추정하는 2가지 방식을 제안하고 실험적으로 검증하였다.

• 한국통신학회논문지
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• 제40권1호
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• pp.165-170
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• 2015

본 논문은 3D 위치 정보를 산출하기 위한 기압고도계 및 기준국을 이용한 절대 고도 측정 정확도 향상에 관한 연구이다. GPS와 같은 위성 항법 시스템이 신뢰성이 있는 절대 고도를 제공하지 못하는 점과 기압 고도계가 변화하는 대기압의 특성상 절대 고도 정보를 제공하지 못한다는 문제점을 인식하고, 이를 개선하기 위해 새로운 기법을 제안하였다. 제안된 기법을 검증하기 위해 RTK를 활용한 기준국을 지정하고 시중에 판매하는 압력 센서 및 EVK 단말기를 활용하였으며, 실내 외에서의 사람의 이동으로 인한 고도 변화 실험과 차량을 이용한 이동 실험을 통해 검증하였다. 이 논문의 결과는 기준국을 이용하는 기존의 2D 측위 시스템을 간단히 3D 측위 시스템으로 확장할 수 있는 저가 솔루션을 제공할 수 있음을 보였다.

• ETRI Journal
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• 제26권3호
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• pp.218-228
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• 2004

Using stereo images with ephemeris data from the Korea Multi-Purpose Satellite-1 electro-optical camera (KOMPSAT-1 EOC), we performed geometric modeling for three-dimensional (3-D) positioning and evaluated its accuracy. In the geometric modeling procedures, we used ephemeris data included in the image header file to calculate the orbital parameters, sensor attitudes, and satellite position. An inconsistency between the time information of the ephemeris data and that of the center of the image frame was found, which caused a significant offset in satellite position. This time inconsistency was successfully adjusted. We modeled the actual satellite positions of the left and right images using only two ground control points and then achieved 3-D positioning using the KOMPSAT-1 EOC stereo images. The results show that the positioning accuracy was about 12-17 m root mean square error (RMSE) when 6.6 m resolution EOC stereo images were used along with the ephemeris data and only two ground control points (GCPs). If more accurate ephemeris data are provided in the near future, then a more accurate 3-D positioning will also be realized using only the EOC stereo images with ephemeris data and without the need for any GCPs.

• Journal of Positioning, Navigation, and Timing
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• 제3권1호
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• pp.31-36
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• 2014

Precise Point Positioning (PPP) is a stand-alone precise positioning approach. As the quality of satellite orbit and clock products from analysis centers has been improved, PPP can provide more precise positioning accuracy and reliability. A combined use of Global Positioning System (GPS) and Global Orbiting Navigation Satellite System (GLONASS) in PPP is now available. In this paper, we explained about an approach for combined GPS and GLONASS PPP measurement processing, and validated the performance through the comparison with GPS-only PPP results. We also used the measurement obtained from the GRAS reference station for the performance validation. As a result, we found that the combined GPS/GLONASS PPP can yield a more precise positioning than the GPS-only PPP.