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정성훈,설동민,이철수,선중규 한국항행학회 2019 韓國航行學會論文誌 Vol.23 No.5
본 논문은 정밀한 전파항법시스템 구현을 위해 안테나의 방향별 군지연 차이가 시스템에 미치는 영향을 분석하였다. 분석은 안테나 시뮬레이션과 시험을 통해서 수행 하였고, 시험은 무반향 챔버에서 진행 하였다. 안테나의 방향별 군지연은 위상(phase)을 기반으로 분석 하였으며, 측정 분석 결과 안테나의 방향별로 최대 약 7.7 ns까지 군지연 차이가 발생했다. 분석된 군지연 차이를 거리로 환산하면 약 2.31 m이며, 이를 실제 TOA (time of arrival)기반의 전파항법시스템에서 시험 하였다. 시험 결과 2.1 m의 거리 변화를 확인 하였으며, 이는 시뮬레이션과 챔버 시험 분석 값과 유사한 수치이다. This paper presents analysis results for the effect of the directional group delay of the antenna to implement a precision radio navigation system. The analysis was conducted through antenna simulation and test, and the test was performed in an anechoic chamber. The directional group delay of the antenna was calculated in phase-based analysis method. The results showed that a variation of up to 7.7ns in group delay occurred per antenna direction. The group delay variation from the analysis is 2.31 meters when converted into distance. It was tested using a real radio navigation system based on the time of arrival (TOA). The test verified the distance variation of 2.1 meters, and this value is similar to those obtained from the simulation and chamber test analysis.
TOA Based Indoor Positioning Algorithm in NLOS Environments
임재욱,이철수,설동민,정성훈,이상범 사단법인 항법시스템학회 2021 Journal of Positioning, Navigation, and Timing Vol.10 No.2
In this paper, we propose a method to improve the positioning accuracy of TOA based indoor positioning system in NLOS environments. TOA based indoor positioning systems have been studied mostly considering LOS environments. However, it is almost impossible to maintain the LOS environments due to obstacles such as people, furniture, walls, and so on. The proposed method in this study compensates the range error caused by the NLOS environments. We confirmed that positioning accuracy of a proposed method is improved than conventional algorithms through simulation and field test.
적분 접근법과 파라메트릭 접근법을 융합한허리 장착 보행항법시스템
주호진,이재홍,박찬국,이철수,설동민 제어·로봇·시스템학회 2019 제어·로봇·시스템학회 논문지 Vol.25 No.4
In this paper, we proposed a pedestrian dead reckoning (PDR) system consisting of an integration approach and a parametric approach. The integration approach is used for obtaining the position by integrating the inertial sensor signal, and the parametric approach is for estimating the stride through the gait characteristic and estimating the position through the estimated step length and walking direction. If the inertial sensor is attached to the shoe, the position can be estimated by the integration approach with a zero velocity update. The integration approach has a disadvantage that the position error increases very quickly if periodic position or velocity correction is not possible. Therefore, when the inertial sensor is mounted at another part, the position is generally estimated through the parametric approach. In the case of the parametric approach, because the step length is estimated through the parameter, there is a disadvantage that the step length estimation error becomes large when the walking motion is not normal. To overcome these drawbacks, we proposed a waist-mounted PDR system combining the integration approach and parametric approach. The performance of the proposed algorithm was verified by experiments.
유성원(Sungwon Yoo),설동민(Dong-Min Seol),이철수(Chulsoo Lee),왕딩양(Dingyang Wang),조성호(Sung Ho Cho) 한국전자파학회 2020 한국전자파학회논문지 Vol.31 No.3
본 논문에서는 벽 투과 환경에서 IR-UWB(Impulse Radio Ultra-wideband) 레이다를 위한 새로운 탐지 알고리즘을 제안한다. 제안하는 방법은 멈춰 있거나 움직이는 표적을 탐지하기 위하여 다중 MTI(Moving Target Indicator)와 CFAR(Constant False Alarm Rate)이 결합된 탐지기를 사용한다. 각 탐지기는 표적의 상태에 맞게 설계되었으며, 특히 수정된 CFAR 방식을 적용하여 빠르게 움직이는 표적을 올바르게 탐지할 수 있도록 하였다. 다른 움직임을 가진 표적들에 대한 높은 탐지율을 달성하기 위하여, CFAR 탐지기의 출력들은 논리적 절차를 통하여 결합된다. 이 결합은 높은 탐지율을 얻을 수 있지만, 또한 오탐율을 상승시킨다. 증가된 오탐율을 억제하기 위하여, CFAR에서 탐지된 신호의 특성을 이용하여 실제 표적과 거짓 표적을 구분한다. 벽 투과 환경에서 다양한 움직임을 가진 다중 표적에 대한 시험을 수행하여, 제안하는 알고리즘이 기존의 방식인 CA(Cell Averaging)-CFAR과 OS(Ordered Statistics)-CFAR에 비하여 탐지율과 오탐율의 측면에서 성능이 향상되었음을 검증하였다. In this paper, we present a novel detection architecture in a through-wall environment using impulse radio ultra-wideband(IR-UWB) radar. In the proposed architecture, multiple moving target indicators and constant false alarm rate(CFAR) detectors are combined to detect both stationary and moving targets. Each detector is designed for the state of targets; in particular, the modified CFAR method is applied to detect fast-moving targets precisely. The outputs of the CFAR detectors are combined through a logical operation to achieve high detection rates for the targets in different movement. This fusion can be used not only to achieve a high detection rate but also increase the false alarm rate. The characteristics of the signals detected on the CFAR are analyzed to reduce the high false alarm rate by classifying the actual target and false target. Experiments were performed for different scenarios of multiple targets using various movements. It is verified that the proposed algorithm has improved performance in terms of both detection rate and false alarm rate compared with conventional approaches, such as cell averaging CFAR and ordered statistics CFAR.