• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.68-73
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• 2004

Flexure measurement of ring laser gyro was investigated by using an interferometer. A two-beam interferometer of Fiezo-fringe pattern obtained the flexure angle in 1-gravity acceleration and the higher acceleration environments. These environments were made with the addition of dummy mass to the ring laser gyro axis. The flexure angle change for 1-gravity acceleration change was measured as 2.37 arcsec/g with low repeatability error of 0.01 arcsec/g. The laser navigation system consisting of 3 flexure-reduced ring laser gyros showed the improvement of flexure error.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.100-103
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• 2011

GFINS(gyro-free inertial navigation system)는 가속도 센서에서 계측된 데이터를 2차 적분하여 yaw를 계산한다. 하지만 가속도 센서는 외란과 적분 오차에 의한 누적오차가 지속적으로 커지는 문제가 있다. 따라서 본 논문에서는 퍼지 추론 시스템(FIS: fuzzy inference system)을 이용해 가속도 센서의 데이터를 보정함으로써 누적오차를 줄이는 방법을 제안한다. 제안된 방법의 성능평가를 위해, 직접 설계한 전방향 AGV를 이용하여 직선과 측면, 대각에 대해 반복 실험하였다. 실험 결과, 제안된 방법이 가속도 센서의 데이터를 효과적으로 보정하는 것을 확인하였다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.200-209
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• 2018

This study proposed a method to select existing facilities as a landmark in order to reset accumulated errors of dead reckoning in a tunnel difficult to receive GNSS signals in automated driving. First, related standards and regulations were reviewed in order to survey 'variety' on shapes and installation locations as a feature of facilities. Second, 'recognition' on facilities was examined using image and Lidar sensors. Last, 'regularity' in terms of installation locations and intervals was surveyed through related references. The results of this study selected a fire fighting box / lamp (50m), an evacuation corridor lamp (300m), a lane control system (500m), a maximum / minimum speed limit sign and a jet fan as a candidate landmark to reset positioning errors. Based on those facilities, it was determined that error correction was possible. The results of this study are expected to be used in repositioning of automated driving vehicles in a tunnel.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.400-408
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• 2018

Wide area augmentation system is a system that generates and transmits correction and Integrity information for use in wide area. Typical system is SBAS. In the United States, it operates under the name WAAS, EGNOS in Europe, MSAS in Japan, SDCM in Russia, GAGAN in India. it is developing Korean SBAS which named KASS by 2022 in Korea. SBAS is a standard System that is operated as civil aviation service base and set as international standards by ICAO. So the correction data can only is used for civil SPS receiver. In this paper, we discuss C1P1 DCB estimation which need to use SPS correction service for PPS receiver. Then we analyze C1P1 DCB correction effect under standalone Satellite Navigation and method to use PPS receiver under SPS DGPS. Finally we organize wide area augmentation system for PPS receiver and analysis performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.4
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• pp.71-80
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• 2006

Strapdown Inertial navigation systems consist of an inertial sensor assembly(ISA), electronic modules to process sensor data, and a navigation computer to calculate attitude, velocity and position. In the ISA, most gryoscopes such as RLGs and FOGs, have digital output, but typical accelerometers use current as an analog output. For a high precision inertial navigation system, sufficient stability and resolution of the accelerometer board converting the analog accelerometer output into digital data needs to be guaranteed. To achieve this precision, the asymmetric error and A/D reset scale error of the accelerometer board must be properly compensated. If the relation between the acceleration error and the errors of boards are exactly known, the compensation and estimation techniques for the errors may be well developed. However, the A/D Reset scale error consists of a pulse-train type term with a period inversely proportional to an input acceleration additional to a proportional term, which makes it difficult to estimate. In this paper, the effects on the acceleration output for auto-pilot situations and the effects of A/D reset scale errors during horizontal alignment are qualitatively analyzed. The result can be applied to the development of the real-time compensation technique for A/D reset scale error and the derivation of the design parameters for accelerometer board.

• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.521-534
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• 2021

Purpose: In this paper, we propose an indoor positioning scheme based on pedestrian dead reckoning using inertial measurement unit. By minimizing the effects of the orientation error of smart-phone, the more accurate estimation for the direction, the step count, and the stride can be achieved. Method: The effectiveness and the performance of the proposed scheme is evaluated by experiments, and it is compared with the conventional scheme in the same conditions. Result: The results showed that the positioning error of the proposed scheme was 0.76m, while that of the conventional scheme was 1.84m. Conclusion: Sine most people carry his/her own smart-phone, the proposed scheme can be helpful to recognize where he/she was and was heading when the fast evacuation is needed in indoors.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.2
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• pp.95-101
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• 2013

The paper investigates the geometric effect of landmarks to the navigation error in the landmark based 3D vision navigation and introduces the INS/Vision integrated navigation system considering its effect. The integrated system uses the vision navigation results taking into account the dilution of precision for landmark geometry. Also, the integrated system helps the vision navigation to consider it. An indirect filter with feedback structure is designed, in which the position and the attitude errors are measurements of the filter. Performance of the integrated system is evaluated through the computer simulations. Simulation results show that the proposed algorithm works well and that better performance can be expected when the error characteristics of vision navigation are considered.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1104-1110
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• 2014

This paper investigates geometric effect of landmarks on three-dimensional navigation error in landmark-based vision navigation systems. Dilution of precision is derived for landmark measurement error on the focal plane of the camera and separately expressed in position DOP and attitude DOP. Values of DOP are observed for various configurations of landmarks.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.479-484
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• 2012

Geometric effect of landmarks to the navigation error is investigated in the two-dimensional line-of-sight measurement based vision navigation system. DOP is derived between line-of-sight measurement error and navigation solution error. For cases of three landmarks in an area, variations of the DOP were observed through computer simulations. Vision navigation system experiments were performed for the cases. Simulation and experimental results show that navigation solution errors have similar trend to DOP values of the simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.2
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• pp.163-170
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• 2016

Tropospheric delay is one of the largest error source in pseudolite navigation system. Because a pseudolite is installed on the ground and transmits its signal to a user in the air or on the ground, the conventional tropospheric delay model developed for a satellite navigation doesn't work properly. In this paper, performance analysis of several pseudolite tropospheric delay models has been done using meteorological data. Based on the result, a new compensation method for Hopfield model has been proposed.