• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.41 no.2
• /
• pp.134-141
• /
• 2013

This paper explores a real-time system implementation to couple tightly StrapDown Inertial Navigation System(SDINS) and Global Positioning System(GPS) mounted on the aircraft. When implementing the SDINS/GPS coupled system in real-time processor, we have to deliberate SDINS's unique characteristics based on the ring laser gyro, and besides, lever-arm, measurements, and error compensation method. The novel modeling method is applied to system the misalignment error term of gyro to estimate the cumulative heading attitude errors while the aircraft banking to turn repeatedly. Captive Flight Test results show that the proposed modeling strategy has good performance.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.14-19
• /
• 2020

This paper proposes a precise drone-positioning technique using a differential global positioning system (DGPS). The proposed system consists of a reference station for error correction data production, and a mobile station (a drone), which is the target for real-time positioning. The precise coordinates of the reference station were acquired by post-processing of received satellite data together with the reference station location data provided by government infrastructure. For the system's implementation, low-cost commercial GPS receivers were used. Furthermore, a Zigbee transmitter/receiver pair was used to wirelessly send control signals and error correction data, making the whole system affordable for personal use. To validate the system, a drone-tracking experiment was conducted. The results show that the average real-time position error is less than 0.8 m.

• Electronics and Telecommunications Trends
• /
• v.23 no.4
• /
• pp.137-146
• /
• 2008

위성항법수신기는 항법위성(GPS)들이 현재 위치와 시간이 담긴 전파신호를 지상으로 송신하면, 이런 신호를 받아 전파가 도달하기까지 걸린 시간을 계산해 자신의 현재 위치를 파악하게 된다. 경도와 위도, 높이를 동시에 파악하기 위해서는 3개 위성신호가 요구되고, 위성간 시간 오차를 제거해 위치 측정의 정확도를 높이기 위한 신호용으로 또 하나의 위성이 필요해 4개 위성이 요구된다. 항법의 형태는 육표기반 항법, 천체기반 항법, 센서기반 항법, 무선기반 항법 및 위성기반 항법으로 분류되며 그 중 전역이고 간섭 영향 및 재밍(jamming)이 어려우며 정확도 측면에서 우수한 위성항법시스템에는 GPS(미국), GLONASS(러시아)가 운용중이고, Galileo(유럽연합), COMPASS(중국), QZSS(일본), IRNSS(인도)이 개발중이다. 위성항법시스템 다원화에 따라 위성항법 수신기 기술도 이중주파수처리 및 타 시스템과의 호환성 제공이 요구되는바, 본 논문에서는 위성항법 수신기 기술 동향을 소개하고자 한다.

• Journal of Advanced Navigation Technology
• /
• v.26 no.6
• /
• pp.404-411
• /
• 2022

The main function in operating the satellite navigation system is to accurately determine the orbit of the navigation satellite and transmit it as a navigation message. In this study, we developed software to determine the orbit of a navigation satellite by combining an extended Kalman filter and an accurate dynamic model. Global positioning system (GPS) and quasi-zenith satellite system (QZSS) orbit determination was performed using international gnss system (IGS) ground station observations and user range error (URE), a key performance indicator of the navigation system, was calculated by comparison with IGS precise ephemeris. When estimating the clock error mounted on the navigation satellite, the radial orbital error and the clock error have a high inverse correlation, which cancel each other out, and the standard deviations of the URE of GPS and QZSS are small namely 1.99 m and 3.47 m, respectively. Instead of estimating the clock error of the navigation satellite, the orbit was determined by replacing the clock error of the navigation message with a modeled value, and the regional correlation with URE and the effect of the ground station arrangement were analyzed.

• Information and Communications Magazine
• /
• v.34 no.4
• /
• pp.17-24
• /
• 2017

본고에서는 저가형 관성 센서를 이용하여 실내 항법을 수행하는 여러 방법들에 대해 알아본다. 저가형 관성 센서를 이용한 추측 항법은 휴대성이 뛰어나고 외부의 인프라 없이 구현이 가능하고 가격이 저렴하다는 장점이 있지만, 오차가 빠르게 누적된다는 단점이 있다. 이를 해결하기 위해 사용자의 보행 특성을 이용한 보행자 추측 항법이 제안되었다. 본고에서는 보행자 추측 항법의 두 분류 기법인 걸음-이동방향 결합 기법과 관성 항법-영속도 보정 결합 기법의 원리와 각 기법들의 기술 동향에 대해 다루고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.12
• /
• pp.44-53
• /
• 2007

In this paper, we focus on the developments of complex location awareness algorithms for real-time location based service and precise/stable localization in the outdoor. In the case of using galileo satellite system along with GPS, several error factor such as the ionosphere can be reduced for an increment of used frequency and visible satellites. Therefore, localization estimation error is no longer having problems with location awareness. But, chips synchronization error induces the error of acquisition and tracking, and the performance of receiver can be decreased. In order to solve this problem, this paper proposes a correlator for performance improvement of receiver in the precise localization.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.9
• /
• pp.734-745
• /
• 2017

The navigation system of lunar lander are composed of various navigation sensors which have a complementary characteristics such as inertial measurement unit, star tracker, altimeter, velocimeter, and camera for terrain relative navigation to achieve the precision and autonomous navigation capability. The required performance of sensors has to be determined according to the landing scenario and mission requirement. In this paper, the specifications of navigation sensors are investigated through covariance analysis. The reference error model with 77 state vector and measurement model are derived for covariance analysis. The mission requirement is categorized as precision exploration with 90m($3{\sigma}$ ) landing accuracy and area exploration with 6km($3{\sigma}$ ), and the landing scenario is divided into PDI(Powered descent initiation) and DOI(Deorbit initiation) scenario according to the beginning of autonomous navigation. The required specifications of the navigation sensors are derived by analyzing the performance according to the sensor combination and landing scenario.

• Proceedings of the KIEE Conference
• /
• 2001.07d
• /
• pp.1946-1948
• /
• 2001

본 논문에서는 저급 관성 센서를 이용한 개인 항법 장치의 모델 및 오차 보정 기법을 제시하고 성능 평가를 위하여 시뮬레이션을 수행하였다. 걸음 검출에 의한 보행 항법에서 중요한 변수인 보폭은 신경 회로망(Neural Network)을 이용하여 결정하였고, 자이로 바이어스 등에 의하여 누적되는 오차는 GPS와의 결합에 의하여 추정, 보상하였다. 이때 GPS와의 결합은 칼만필터를 이용하였으며 칼말필터를 구성하는데 필요한 오차 모델 및 결합 방법을 제시하였다. WNS/GPS 결합에 의하여 오차의 발산을 막을 수 있으며 GPS신호가 중간에 단절되는 경우에도 오차가 발산하지 않고 좋은 결과를 유지함을 보인다.

• 한국해양학회지
• /
• v.14 no.2
• /
• pp.78-85
• /
• 1979

Korea has not any fixed station for Radio Navigation systems yet. In some part of the Korean Sea, however, Japanese stations can be utilized for the Radio Navigation. 3 Decca chains were proposed to install the Decca Navigation network for Korea. Only for the coverage area, 1 Decca chain is sufficient for the sea around Korea instead of 3 chains. At present, Omega system is the most recommendable for the positioning in the farther area. In nearshore area, Raydist or Decca Trisponder is is useful for obtaining the position with high accuracy.

• Journal of Navigation and Port Research
• /
• v.37 no.1
• /
• pp.35-40
• /
• 2013

In the eLoran navigation system, the dominant deterioration factors of navigation accuracy are the TOA measurement errors on user receiver and the GDOP between the receiver and the transmitters. But if the ASF data measured at dLoran reference station are provided for users through the Loran data channel, it will be possible to correct the TOA measurement errors. The position accuracy can be determined by the DOP depending on the geometry of receiver-transmitters, and their optimal placement improves the navigation accuracy. In this study we determined the geometric placement in case of up to six stations, and evaluated the performance of position accuracy for the receiver-transmitter geometry set of eLoran stations. The proposed geometry of eLoran stations can be referred for the construction of eLoran infrastructure meeting the capability of HEA for maritime, and time/frequency users in Korea.