• 제어로봇시스템학회논문지
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• 제8권1호
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• pp.74-79
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• 2002

A fast and practical method is proposed to resolve the half cycle ambiguity by comparing data sequences from multiple antennas. The method uses the fact that demodulated data sequences from multiple antennas are identical for the same SV (Satellite Vehicle). The performance of the proposed method is evaluated using an attitude determination system. the test results show that the half cycle ambiguity can be resolved within a few bit periods after carrier lock and a seamless attitude is obtained.

• 한국항행학회논문지
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• 제15권4호
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• pp.502-509
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• 2011

GPS 반송파를 이용한 정밀 항법 수행 시 미지 정수 결정이 필수적이다. 한번 결정된 미지 정수는 사이클 슬립이 발생하지 않는 한 변하지 않는다. 그러나 전파 관측 환경의 변화에 따라 사이클 슬립이 발생하게 되며, 이러한 상황에서 연속적인 항법 정보 제공을 위한 적절한 대응 조치를 취해 주어야 한다. 그러나 이러한 조치들은 매우 번거로우며, 소프트웨어적인 복잡성을 야기 한다는 문제가 있다. 본 논문에서는 미지 정수 유지 및 재검색 과정을 단순화하기 위해 시스템 운동 모델을 이용하여 사이클 슬립에 무관한 위치 제공 기법을 제안하였다. 제안된 방법은 고의적으로 사이클 슬립을 발생시켜 대응 성능을 확인하였으며, 이 결과 사이클 슬립과 무관하게 항법 정보를 제공할 수 있음을 확인하였다.

• Korean Journal of Geomatics
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• 제3권2호
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• pp.129-140
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• 2004

This paper addresses solutions th the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as th cumulative-sun (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 Korea-Russia Joint Conference on Geometics
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• pp.82-94
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• 2004

This paper addresses solutions to the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The occurrence of a cycle slip that is undetected is, however, can significantly degrade the filter's performance. This contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• International Journal of Aeronautical and Space Sciences
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• 제6권2호
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• pp.17-22
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• 2005

As one of validation tool for attitude determination system, we have used various constraints using priori information which is known through base vector set up. However these conventional constraints cannot guarantee validity in terms of final solutions such as Euler angle. So we suggest attitude boundary concept to verify the final attitude solution on the flying airplane, it is based on the combination of velocity based attitude estimation technique and ambiguity resolution. we can say it can check invalid solution effectively at just one epoch without repeatability test of resolved cycle ambiguity. In this paper we show that the suggested constraint can effectively reject incorrectly resolved cycle ambiguity the conventional constraints have missed.

• Journal of Electrical Engineering and Technology
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• 제7권4호
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• pp.615-625
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• 2012

GPS attitude outputs or carrier phase observables can be effectively utilized to compensate the attitude error of the strapdown inertial navigation system. However, when the integer ambiguity is not correctly resolved and/or a cycle slip occurs, an erroneous GPS output can be obtained. If the erroneous GPS output is applied to the attitude determination GPS/INS (ADGPS/INS) integrated navigation system, the performance of the system can be degraded. This paper proposes an ADGPS/INS integration system using the triple difference carrier phase observables. The proposed integration system contains a cycle slip detection algorithm, in which the inertial information is combined. Computer simulations and flight test were performed to verify effectiveness of the proposed navigation system. Results show that the proposed system gives an accurate and reliable navigation solution even when the integer ambiguity is not correctly resolved and the cycle slip occurs.

• 제어로봇시스템학회논문지
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• 제9권9호
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• pp.736-744
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• 2003

The GPS attitude output or carrier phase observables can be effectively utilized to compensate the attitude error of the strapdown inertial navigation system. However, when the integer ambiguity is not correctly resolved and/or a cycle slip occurs, an erroneous GPS output can be obtained. If the erroneous GPS information is directly applied to the AGPS/INS integration system, the performance of the system can be rapidly degraded. This paper proposes an AGPS/INS integration system using the triple difference carrier phase observables. The proposed integration system contains a cycle slip detection algorithm, in which inertial information is combined. Computer simulations and van test were performed to verify the proposed integration system. The results show that the proposed system gives an accurate and reliable navigation solution even when the integer ambiguity is not correct and the cycle slip occurs.

• International Journal of Aeronautical and Space Sciences
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• 제13권2호
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• pp.250-259
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• 2012

The need for position information in indoor environments has been growing lately. Several indoor navigation systems have been studied. Among them, pseudolite-based indoor positioning systems are one of the best systems to obtain precise position measurements. However, the installation of such systems is very difficult because the calibration of pseudolite antenna position is complicated. For precise calibration, the use of carrier phase measurements is necessary, and whenever carrier phase measurements are considered, problems with cycle ambiguity appear. In this paper, a new approach to calibrate the positions of pseudolite antennas is proposed. By using a multi-antenna, the ambiguity can be eliminated, epoch by epoch, for every single carrier phase measurement. Moreover, the number of calibration points can be reduced down to 3 by use of measurements collected at unknown positions. Using the proposed methods, the process of the collection of carrier phase measurements becomes considerably simple and convenient. Simulation results are presented to verify the proposed algorithms.

• 한국측량학회지
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• 제14권2호
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• pp.167-179
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• 1996

AFM은 반송파 위상을 이용하는 GPS 정밀측위에서 일반적으로 문제가 되는 초기미지정수와 cycle-slip에 영향을 받지 않는 기법이다. 그러나 기존의 AFM알고리즘에는 두 가지의 어려움이 있다. 첫째, 최적의 수신기 위치를 구하기 위한 계산시간이 너무 길다는 점이다. 둘째, 검색공간 내에 최적의 수신기 위치로 선정이 가능한 후보가 많을 수 있다는 점이다. 따라서 기존의 AFM 알고리즘이 갖는 단점을 개선하여 OTF의 환경에 적용할 수 있도록 계산시간을 획기적으로 단축시키는 새로운 알고리즘이 본 논문에서 제시되었다. 또한 결정된 최적의 수신기 위치의 진위 여부를 통계적으로 검정하는 알고리즘이 제시되었다.

• 한국항행학회논문지
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• 제2권1호
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• pp.3-10
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• 1998

GPS는 기존의 주 용용분야인 항법시스템으로서 뿐만 아니라 최근 들어와서는 보정위성항법의 원리와 미지정수(Integer Cycle Ambiguity)결정 알고리즘을 이용하여 GPS수신기와 3~4개의 안테나로 자세결정을 하는데 이용되고 있다. 본 연구에서는 고가의 패치(Patch) 안테나를 장착한 수신기를 사용하지 않고 저가의 수신기 여러 대를 이용하여 자세결정을 할 수 있도록 이중차분(Double Difference)을 한 측정식을 이용하여 칼만필터를 통해 자세결정을 할 수 있는 알고리즘을 제시하고 모의실험을 통해 제시한 알고리즘의 유용성을 고찰한다.