• 제어로봇시스템학회논문지
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• 제19권2호
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• pp.131-139
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• 2013

In recent years alternative navigation system such as a DBRN (Data-Base Referenced Navigation) system using geophysical information is getting attention in the military navigation systems in advanced countries. Specifically TRN (Terrain Referenced Navigation) algorithm research is important because TRN system is a practical DBRN application in South Korea at present time. This paper presents an integrated navigation algorithm that combines a linear profile-based TRN and INS (Inertial Navigation System). We propose a correlation analysis method between TRN performance and terrain roughness index. Then we propose a conditional position update scheme that utilizes the position output of the conventional linear profile type TRN depending on the terrain roughness index. Performance of the proposed algorithm is verified through Monte Carlo computer simulations using the actual terrain database. The results show that the TRN/INS integrated algorithm, even when the initial INS error is present, overcomes the shortcomings of linear profile-based TRN and improves navigation performance.

• 한국측량학회지
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• 제37권5호
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• pp.367-377
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• 2019

As an alternative navigation system for the non-GNSS (Global Navigation Satellite System) environment, a new type of DBRN (DataBase Referenced Navigation) which applies both gravity gradient and terrain, and combines filter-based algorithm with profile matching was suggested. To improve the stability of the performance compared to the previous study, both centralized and decentralized EKF (Extended Kalman Filter) were constructed based on gravity gradient and terrain data, and one of filters was selected in a timely manner. Then, the final position of a moving vehicle was determined by combining a position from the filter with the one from a profile matching. In the simulation test, it was found that the overall performance was improved to the 19.957m by combining centralized and decentralized EKF compared to the centralized EKF that of 20.779m. Especially, the divergence of centralized EKF in two trajectories located in the plain area disappeared. In addition, the average horizontal error decreased to the 16.704m by re-determining the final position using both filter-based and profile matching solutions. Of course, not all trajectories generated improved performance but there is not a large difference in terms of their horizontal errors. Among nine trajectories, eights show smaller than 20m and only one has 21.654m error. Thus, it would be concluded that the endemic problem of performance inconsistency in the single geophysical DB or algorithm-based DBRN was resolved because the combination of geophysical data and algorithms determined the position with a consistent level of error.

• 한국측량학회지
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• 제32권1호
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• pp.63-73
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• 2014

최근 의도적인 간섭 또는 전파교란으로 인한 위성기반항법시스템(GNSS)의 정확도 저하 문제가 대두되면서 GNSS를 사용할 수 없는 환경에 대응할 수 있는 항법 기술 중 하나로 데이터베이스(DB)를 기반으로 한 항법 연구가 진행되고 있다. 본 연구에서는 지구물리 DB 중 중력구배를 선정하여 우리나라 중력구배 DB를 구축하고, 확장형칼만필터(EKF)를 적용하여 중력구배기반 항법을 구현하였다. 항법 성능은 시뮬레이션을 통해 분석하였으며, 우리나라 전역에 14개의 비행궤적을 생성한 후 다양한 DB와 센서 오차, 그리고 고도에 따른 영향을 고려하였다. 비행성능을 분석한 결과 DB와 센서 오차가 작을수록, 고도가 낮을수록 정밀한 항법이 가능함을 확인하였다. 또한, DB 기반의 항법시스템 중 가장 널리 알려진 지형참조 항법과 상대적인 성능 분석을 수행한 결과, 고도가 낮은 경우는 DB 및 센서 오차와 무관하게 대체로 중력구배기반 항법이 우수한 성능을 나타내었다. 그러나 고도가 높아지면 높은 정밀도의 중력구배계와 중력구배 DB를 탑재한 경우에만 지형참조 항법의 결과와 유사한 수준의 항법이 가능하였다. 본 연구에서 고려한 DB와 센서 오차, 고도 외에도 DB 해상도, 비행속도 및 갱신 주기 등 중력구배기반 항법에 영향을 미치는 다양한 요인이 있으므로 이를 고려한 분석이 추가로 수행되어야 할 것이다.