• 한국군사과학기술학회지
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• 제13권4호
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• pp.708-715
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• 2010

In Strapdown Inertial Navigation System, alignment accuracy is the most important factor to determine the performance of navigation. However by an existing self-alignment method, it takes a long time to acquire the alignment accuracy that we want. So, to attain the desired alignment accuracy in as little as $\bigcirc$ minutes, we have developed the precise multi-position alignment method. In this paper, it is proposed a inertial measurement matching transfer alignment method among alignment methods to minimize the alignment error in a short time. It is based on a mixed velocity-DCM matching method be suitable to the operating environment of vertical launching system. The compensation methods to reduce misalign error, especially azimuth angle error incurred by measurement time-delay error and body flexure error are analyzed and evaluated with simulation. This simulation results are finally confirmed by experimentations using FMS(Flight Motion Simulator) in Lab and the integration test to follow the fire control mission.

• 한국군사과학기술학회지
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• 제4권1호
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• pp.225-233
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• 2001

This paper deals with the transfer alignment problem of SDINS(StrapDown Inertial Navigation System) subjected to roll and pitch motions of the ship. Specifically, to reduce alignment errors induced by measurement time-delay and ship body flexure, an error compensation method is suggested based on delay state augmentation and DCM(Direction Cosine Matrix) partial matching. A linearized error model for the velocity and attitude matching transfer alignment system is first derived by linearizing the nonlinear measurement equation with respect to its time delay and augmenting the delay state into the conventional linear state equations. And then DCM partial matching is properly combined to reduce effects of a ship's Y axis flexure. The simulation results show that the suggested method is effective enough resulting in considerably less azimuth alignment errors.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1403-1406
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• 1997

Generally, G.P.S(Global Positioning System) is using for the car navigation system but it has some restrictions such as the discontinuity of earth satellites and SA (Selective Availability). Recently, the hybrid navigation system combining with G.P.S and Dead-reckoning are much attractuve for improving the accuracy of a vehicle positioning. G.P.S called satellite navigation system, can measure its position by using satellites. Dead-Reckoning is the self-contained navigatioin system using a wheel sensor for the vehicle velocity and a gyro sensor for the vehicle angular velocity. Some algorithm could be generated for finding the vehicle position and orientation. In this paper, we developed a hybrid algotithm wiht G.P.S DR and Map-Matching.

• 전자공학회논문지A
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• 제32A권2호
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• pp.96-110
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• 1995

Traveling-wave electrodes for the high-speed Ti:LiNbO$_{3}$ modulators are designed. For a solution to the problems of 1) phase-velocity mismatching between the optical wave and the Modulating M/W, 2) M/W electrode characteristic impedance mismateching, we assume devices with 1$\mu$m thick SiO$_{2}$ buffer layer between the electrode and the Ti:LiNbO$_{3}$ substrate. The electrode analyses are performed by the FEM using the second-order triangular elements. The optimum design parameters to satisfy the phase-velocity matching and the characteristic impedance matching are sought for. By use of the analyses' results, a Mach-Zehnder optical modulator with a CPW electrode is designed as an example. the band-width estimation is also illustrated.

• 전자공학회논문지S
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• 제35S권2호
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• pp.146-156
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• 1998

Thispapr proposes hybrid navigation parameter estimation using sequential aerial images. The proposed navigation parameter estimation system is composed of two parts: relative position estimation and absolute position estimation. the relative position estimation recursively computes the current velocity and absolute position estimation. The relative position estimation recursively computes the current velocity and position of an aircraft by accumulating navigation parameters extracted from two succesive aerial images. Simple accumulation of parameter values decreases reliability of the extracted parameters as an aircraft goes on navigating. therefore absolute position estimation is required to compensate for position error generated in the relative position step. The absolute position estimation algorithm combining image matching and digital elevation model(DEM) matching is presented. Computer simulation with real aerial image sequences shows the efficiency of the proposed hybrial algorithm.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.410-416
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• 2001

An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity field of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. In this study, stereo photogrammetty was applied for the 3-D matching of tracer particles. Epipolar line was used to decect the stereo pair. 3-D CFD data was used to estimate algorithm. 3-D position data of the first frame and the second frame was used to find velocity vector. Continuity equation was applied to extract error vector. The algorithm result involved error vecotor of about 0.13 %. In Pentium III 450MHz processor, the calculation time of cross-correlation for 1500 particles needed about 1 minute.

• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.224-225
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• 2003

Since group velocity (GV) mismatch significantly limits the efficiency of nonlinear interactions such as second harmonic generation (SHG), several techniques have been developed to compensate GV mismatch. The simplest way to avoid the GV mismatch problem is to reduce the device length. However, it results in a poor trade-off between the SHG spectral bandwidth and the conversion efficiency. (omitted)

• 제어로봇시스템학회논문지
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• 제8권2호
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• pp.178-184
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• 2002

This paper deals with the transfer alignment problem of SDINS(StrapDown Inertial Navigation System) subjected to roll and pitch motions of the ship. In order to reduce alignment errors induced by ship body flexure, a linearized error model for the velocity and attitude matching transfer alignment system is first derived by linearizing the nonlinear measurement equation with respect to the dominant y axis component and defining the flexure state of random constant type. And then a robust state estimation scheme is introduced to account for modeling uncertainty of the flexure. By interpreting the simulation results and comparing with the velocity and DCM(Direction Cosine Matrix) partial matching method, it is shown that the proposed method is effective enough to improve the azimuth alignment performance.

• 융합신호처리학회논문지
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• 제20권3호
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• pp.171-176
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• 2019

드론은 원거리 동영상을 효율적으로 획득할 수 있어서 활용성이 높다. 드론 운용에서 속도의 크기인 속력은 설정할 수 있지만 이동하는 방위의 정확한 값은 설정이 불가능하다. 본 논문에서는 드론에서 획득한 동영상을 이용하여 일정한 속도로 이동하는 드론의 속도를 추정한다. 기준 프레임과 표적 프레임의 Sum of Absolute Difference(SAD)를 최소로 하는 표적 프레임의 변위를 구한다. 드론의 실제 속도(Ground Truth)는 각 프레임에서 일정한 동일 지점(Matching Point)의 위치를 이용하여 계산한다. 실험에서 150m 상공에서 일정한 속력으로 이동하는 드론으로 동영상을 획득하였다. 추정한 x와 y방향의 속도와 속력의 평균 제곱근 오차(RMSE)를 구하여 제안한 방법의 신뢰성을 보였다.

• 한국측량학회지
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• 제28권1호
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• pp.73-82
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• 2010

지형 참조 항법 기술 중 하나인 TERCOM은 순항미사일에 장착되어 있는 시스템으로 현재까지도 지속적으로 연구되고 있는 기술이다. 본 논문에서는 영역기반 정합 기법과 확장형 칼만필터를 이용하여 TERCOM에 기반한 지형 참조 항법을 시뮬레이션을 통해 분석하였다. 영역기반 정합의 유사성 분석에는 평균제곱오차 알고리즘과 상호상관정합 알고리즘을 적용하였다. 기압 고도계와 레이더 고도계, SRTM DTM을 탑재한 항체가 시속 1000km로 545초 간 장방형 궤적으로 비행하도록 시뮬레이션 하였으며, 그 결과 평균제품오차 기반 알고리즘의 거리 오차의 표준연차는 99.6m 상호상판정합 기반 알고리즘은 34.3m로 상호상관정합 기반 알고리즘이 상대적으로 지형에 덜 민감하고 두 알고리즘 모두 지형의 기복 정도에 따라 항법 정밀도의 편차가 큰 것으로 나타났다. 따라서 완만한 지형에도 민감한 알고리즘과 관성항법 적분오차 증가에 따라 적절한 탐색영역의 크기 결정, 비행환경에 따라 요구되는 최적의 지형 데이터베이스의 해상도 결정 등에 대한 연구가 수행되어야 할 것으로 판단된다.