• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.186-186
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• 2000

In the GPS/DR integrated system, the GPS position(or velocity) is used to compensate the DR output and to calibrate errors in the DR sensor. This synergistic relationship ensures that the calibrated DR accuracy can be maintained even when the GPS signal is blocked. Because of the observability problem, however, the DR sensors are not sufficiently calibrated when the vehicle speed is low. This problem can be solved if we use a multi-antenna GPS receiver for attitude determination instead of conventional one. This paper designs a two-antenna GPS receiver integrated with DR sensors. The proposed integration system has three remarkable features. First, the DR sensor can be calibrated regardless of the vehicle speed with the aid of two-antenna GPS receiver. Secondly, the search space of integer ambiguities in GPS carrier-phase measurements is reduced to a part of the surface of the sphere using DR heading. Thirdly, the detection resolution of cycle-slips in GPS carrier-phase measurements is improved with the aid of DR heading. From the experimental result, it is shown that the search grace is drastically reduced to about 3120 of the non-aided case and the cycle-slips of 1 or half cycle can be detected.

• Journal of Mechanical Science and Technology
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• 제19권8호
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• pp.1529-1543
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• 2005

Recently an unmanned aerial vehicle (UAV) has been widely used for military and civil applications. The role of a navigation system in the UAV is to provide navigation data to the flight control computer (FCC) for guidance and control. Since performance of the FCC is highly reliant on the navigation data, a fault in the navigation system may lead to a disastrous failure of the whole UAV. Therefore, the navigation system should possess a fault detection and isolation (FDI) algorithm. This paper proposes an attitude determination GPS/INS integrated navigation system with an FDI algorithm for a UAV. Hardware for the proposed navigation system has been developed. The developed hardware comprises a commercial inertial measurement unit (IMU) and the integrated navigation package (INP) which includes an attitude determination GPS (ADGPS) receiver and a navigation computer unit (NCU). The navigation algorithm was implemented in a real-time operating system with a multi-tasking structure. To evaluate performance of the proposed navigation system, a flight test has been performed using a small aircraft. The test results show that the proposed navigation system can give accurate navigation results even in a high dynamic environment.

• 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.

• 한국항공우주학회지
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• 제35권3호
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• pp.260-267
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• 2007

GAK(GPS adapter kit)은 GPS/INS 항법 모듈을 내장한 사거리 연장 키트의 일종으로 자유 낙하식 폭탄에 장착하여 투하 정확도의 향상을 목적으로 한다. 본 논문에서는 GAK 항법 모듈의 차량 시험 결과를 제시하였다. 항법 모듈은 상용의 MEMS IMU, 내장형 GPS 수신기 및 항법 컴퓨터로 구성된다. GPS 수신기는 위성 가시성 향상 및 자세 측정을 위하여 다중 안테나를 사용하는 구조로 설계하였다. 실시간 항법 소프트웨어는 모듈화 구조로 설계하여 유지보수성 및 확장성을 고려하였다. 항법 모듈의 성능을 평가하기 위해 고성능 INS인 Honeywell H-726 MAPS를 탑재한 차량 시험을 수행하였다. 차량 시험 결과 GPS 자세 결과를 사용한 GAK 통합 합법 모듈이 일반적인 GPS/INS 통합의 경우에 비하여 더 나은 항법 성능을 나타내었으며 재밍 환경을 고려한 경우에도 순수 항법에 비하여 우수한 coasting 성능을 제공하였다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2002년도 창립 20주년기념 국제학술대회
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• pp.77-84
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• 2002

The Global Positioning System, GPS technology has been widely used in positioning and attitude determination. It is well known that the accuracy, availability and reliability of the positioning results are heavily dependent on the number and geometric distribution of tracked GPS satellites. Because of this limitation, in some situations, such as in urban canyons, underground space or inside of buildings, it is really hard to navigate with GPS receiver. Therefore, in order to improve the performance of satellite-based positioning, the integration of GPS with the pseudolite technology has been proposed. With this pseudolite technology, it is expected that seamless positioning service can be provided in wider area without replacing existing GPS receivers. On the other hand, to adopt pseudolites at larger scale, it is necessary to verify how the pseudolites can complement the existing GPS-based positioning. In this paper the authors present the detail of experimental investigations and the results of the fundamental verification for seamless positioning using integration of GPS and pseudolite. This paper shows that the accuracy and efficiency of integrating GPS and pseudolite through the dynamic and static positioning experiment and discuss about the influence on GPS receiver by pseudolite signal. The experimental results indicate that the accuracy of the height component can indeed be significantly improved, to approximately the same level as the horizontal component.

• Korean Journal of Geomatics
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• 제2권1호
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• pp.17-24
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• 2002

The Global Positioning System technology has been widely used in positioning and attitude determination. It is well known that the accuracy, availability and reliability of the positioning results are heavily dependent on the number and geometric distribution of tracked GPS satellites. Because of this limitation, in some situations, such as in urban canyons, underground or inside of buildings, it is difficult to navigate with GPS receiver. Therefore, in order to improve the performance of satellite-based positioning, the integration of GPS with the pseudolite technology has been proposed. With this pseudolite technology, it is expected that seamless positioning service can be provided in a wider area without replacing existing GPS receivers. On the other hand, to adopt pseudolites on a larger scale, it is necessary to verify how the pseudolites may complement the existing GPS-based positioning. In this paper the authors present the details of the experiments and the results of the fundamental verification for seamless positioning using integration of GPS and pseudolite. This paper shows that the accuracy and efficiency of integrating GPS and pseudolite through the dynamic and static positioning experiment. The influence of pseudolite signal on GPS receiver is also discussed. The experimental results indicate that the accuracy of the height component can indeed be significantly improved, to approximately the same level as the horizontal component.

• 제어로봇시스템학회논문지
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• 제13권10호
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• pp.1025-1031
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• 2007

GPS is widely used for positioning applications and attitude of a vehicle can be found also with multiple antennas. However, extremely weak signal level prevents GPS from indoor operation. DR with accelerometers and gyros and landmark based localization method used for indoor applications increase complexity and cost. In this paper, a simple but very efficient ultrasound based attitude determination system which determines both position and attitude in WSN is given. The range between transmitter and receivers are measured using the arrival time difference between ultrasound and RF signal. The 3 dimensional positions can be found using more than 3 range measurements. Furthermore, if more than 2 transmitters are used, the attitude can be determined using the baseline vectors obtained by differencing transmitter and receiver positions. The prototype system is implemented to evaluate the performance of the proposed method. In addition, an error analysis shows the relation between the attitude error and basel me length, quality of measurement and orientation of a vehicle. The static and dynamic experiments performed by micro mobile robot shows accurate position with less than 1.5cm error and attitude with less than 1 degree error can be obtained continuously with 20cm baseline. It is expected that these results can be adapted without modification to indoor applications such as home cleaning robot and autonomous wheelchair maneuvering.

• 한국항공우주학회지
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• 제45권2호
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• pp.106-113
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• 2017

항공기 및 지상 이동체 등에 사용되는 자세 및 방위 결정 시스템은 자세를 결정하기 위해 중력가속도 벡터와 지구자기장 벡터를 이용한다. 이를 위해 가속도계와 자력계를 이용하게 되는데, 가속도계의 경우 중력가속도뿐만 아니라 항체의 운동 가속도까지 포함하게 되어 가속 중에는 자세결정이 어려워진다. 본 논문에서 다루는 가속도 보상 방법은 가속도계에서 얻은 비력으로부터 GPS 수신기를 통해 계산한 항체의 가속도를 빼주어 이를 해결하는 방법이다. 기존의 알고리즘은 보상한 벡터를 상수 형태로 간주해 이용하게 되는데, 본 논문에서는 이로 인한 오차를 분석하고 측정치로부터 모델을 재유도해 성능을 개선했다. 기존의 알고리즘이 내포한 오차 요인과 본 논문에서 제안한 알고리즘에 의해 자세 추정 성능이 개선됨을 컴퓨터 시뮬레이션을 통해 확인했다.

• 대한토목학회논문집
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• 제29권1D호
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• pp.135-143
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• 2009

GPS 반송파를 사용하는 GPS/INS 통합 측위 기술은 서로가 가지는 기술적 한계를 상호 극복하여 그 성능을 최대화 할 수 있어 측량과 항법의 다양한 분야에 활용되고 있다. 그러나 GPS/INS 통합 측위을 통하여 수 센티미터의 정확도를 확보하기 위해서는 기준국과 이동국 수신기 사이의 간격이 10~20Km 이내로 제한되어야 하는 단점을 가지고 있으며 이는 두 시스템 관측데이터를 통합 처리하더라도 그 정확도는 여전히 GPS 위성궤도 오차, 전리층 영향 그리고 대류권 지연과 같은 기선장에 따른 오차의 영향을 받기 때문이다. 이것은 3대 이상의 기준국 관측데이터를 사용하여 기선장에 따른 오차 보정량을 추정하여 이동국 관측데이터에서 그 영향을 최소화하여 극복 할 수 있다. 따라서 본 논문에서는 다중의 기준국 관측데이터를 사용하여 기선장에 따른 오차 보정량 결정을 위한 기준국 반송파 미지정수 결정, 칼만필터에 의한 기선장에 따른 오차 추정 그리고 기준국과 이동국의 기하관계에 의한 오차 보간을 통한 보정량 산출 알고리즘 제안하고 실제 관측데이터 처리를 통해 그 성능을 평가 하였다.