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저궤도위성 추력기 기반 궤도제어모드에서 궤도 각속도 변화에 따른 안정화 연구
최홍택(Hong-Taek Choi),오시환(Shi-Hwan Oh),용기력(Ki-Lyuk Yong) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
After LEO satellite is launched, it performs the mission on the mission orbit. In general, attitude control subsystem for the LEO satellite consists of ground test mode, safe hole mode, orbit maintenance mode, standby mode and image mode to perform the mission. The satellite performs orbit correction and maintenance and inclination correction and maintenance using thruster after the insertion of the mission orbit. The internal disturbance is caused by thruster which is equipped with incorrectly, change of center of mass, and thrust level, etc. Nutation is also derived during ΔV to change altitude and inclination. Roll and pitch axis rotation is necessary for ΔV. In order to eliminate nutation angle and to stabilize the satellite, ΔV requires correct orbital rate. In this study, we reviewed the orbital rate according to reference frame and compare the attitude date with the requirement of the ΔV.
저궤도 위성 추력기의 교란토크를 고려한 위치 및 방위 설계
최홍택(Hong-taek Choi),김종범(Jong-Bum Kim),공현철(Hyeon-Cheol Gong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Attitude control subsystem for the LEO satellite consists of contingency mode, maneuver mode and mission mode to perform the mission. The contingency mode is divided into sun acquisition submode, sun pointing submode and gyroless submode, and the maneuver mode is divided into attitude hold submode and △Ⅴ submode, while the mission mode divided into recess submode and image submode. In this paper, I designed thruster location and orientation of which was used for sun acquisition submode and maneuver mode as an actuator considering thruster disturbance torque uncertainty for LEO satellite.
제어모멘트자이로와 반작용휠의 순차적 사용을 통한 위성 고기동 연구
손준원(Jun-Won Son),최홍택(Hong-Taek Choi) 한국항공우주연구원 2014 항공우주기술 Vol.13 No.2
네 개의 반작용휠이 장착된 위성에 두 개의 우주검증용 제어모멘트자이로가 탑재되었다고 가정하고, 이들을 이용한 위성 고기동 방법에 대해서 연구해 보았다. 토크가 큰 제어모멘트자이로를 먼저 사용하여 위성의 자세오차를 줄인 후에, 반작용휠을 통해 나머지 자세오차를 제어하는 방법을 제안하였다. 본 방법을 사용할 경우, 제어모멘트자이로에서 발생하는 특이점 문제를 회피할 수 있으며, 토크 명령 계산시 김벌각 정보가 필요 없다는 장점이 있다. 또한 시뮬레이션을 통해, 본 방법이 기존에 연구된 방법들에 비해 위성의 기동성능에는 큰 차이가 없으며, 필요한 반작용휠의 모멘텀도 크게 줄어드는 것을 확인하였다. We assume that two control moment gyros are installed for space qualification in a satellite with four reaction wheels, and study the high agile maneuver method. Using high torque control moment gyros, we reduce the satellite"s attitude error. After that, we activate reaction wheels to control remaining attitude error. This proposed method can avoid singularity problem of control moment gyros, and do not require gimbals" angle to calculate torque command. Through numerical simulations, we show that our method"s agile performance is similar to previous method and reduce the reaction wheels" required momentum.
임조령(Jo Ryeong Yim),최홍택(Hong-Taek Choi) 한국항공우주연구원 2012 항공우주기술 Vol.11 No.2
본 기술논문에서는 고기동 고정밀 위성의 별 추적기 초기 점검 원격측정 데이터가 분석되었다. 최근에 발사된 위성은 고기동 고정밀 위성이므로 고도의 요구조건을 만족하기 위해 광학계, 전자부, 배플이 분리된 형태로 광학계 부분의 온도를 20 degC 근처로 유지하면서 저주파 오차 성능을 향상 시킨 프랑스 SODERN사의 SED36을 사용하였다. 본 논문에서는 위성으로부터 내려 받은 원격측정 데이터의 처리를 통해 초기 점검 상태, 요구 조건 만족 여부, 이상 현상 및 주요 임무 기동에서의 별 추적기 잡음각 성능 분석 결과를 제시하였다. This technical paper describes the analysis results of telemetry data for the initial activation of star trackers for an agile high accuracy low earth orbit satellite. The satellite was recently launched and is in the Launch and Early Operation Phases. It uses two SED36 star trackers manufactured by SODERN. The star tracker is separated by three parts, an optical head, an electronics box, and a baffle with maintaining optical head base plate temperature 20 degC in order to achieve the better performance in low frequency error. This paper presents the initial activation status, requirements and performance, anomaly occurrence, and noise equivalent angle performance analysis during the mission mode by processing the telemetry data.
스텝핑 모터 특성에 따른 2축 짐발 안테나 시스템의 미소진동 측정 시험
김대관(Kim Dae-Kwan),최홍택(Choi Hong-Taek),박지용(Park Gee-Yong) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
A 2-axis gimbal system is one of main disturbance sources affecting on image jitter response of a satellite. The gimbal system can be rotated on its azimuth and elevation axes, resulting in variation of its moment of inertia and structural modes, so that generates non-linear vibration characteristics. In order to estimate the jitter response, it is an indispensable process to characterize micro-vibration disturbance of the 2-axis gimbal system. In the present research, the vibration characteristics of the 2-axis gimbal system was investigated with respect to the types of stepping motors. The micro-vibration tests were performed for 2-phase and 5-phase stepping motors. The test results show that the disturbance can be reduced with vibration attenuation ratio of 60% by replacing the 2-phase stepping motor with the 5-phase one.