• Title/Summary/Keyword: 위성 자세 제어

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Analytical Solution for Attitude Command Generation of Agile Spacecraft (고기동 인공위성의 해석적 자세명령생성 기법 연구)

  • Mok, Sung-Hoon;Bang, Hyochoong;Kim, Hee-Seob
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.8
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    • pp.639-651
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    • 2018
  • An analytical solution to generate attitude command profile for agile spacecraft is proposed. In realistic environment, obtaining analytical minimum-time optimal solution is very difficult because of following constraints-: 1) actuator saturation, 2) flexible mode excitation, 3) uplink command bandwidth limit. For that reasons, this paper applies two simplifications, an eigen-axis rotation and a finite-jerk approximated profile, to derive the solution in an analytical manner. The resulting attitude profile can be used as a feedforward or reference input to on-board attitude controller, and it can enhance spacecraft agility. Equations of attitude command profile are derived in two general boundary conditions: rest-to-rest maneuver and spin-to-spin maneuver. Simulation results demonstrate that the initial and final boundary conditions, in terms of time, attitude, and angular velocities, are well satisfied with the proposed analytical solution. The derived attitude command generation algorithm may be used to minimize a number of parameters to be uploaded to spacecraft or to automate a sequence of attitude command generation on-board.

A Study of Spacecraft Alignment Measurement with Theodolite (데오도라이트를 이용한 위성체 얼라인먼트 측정에 관한 연구)

  • Yun,Yong-Sik;Park,Hong-Cheol;Son,Yeong-Seon;Choe,Jong-Yeon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.31 no.10
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    • pp.105-111
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    • 2003
  • A measurement of spacecraft alignment is an important process of spacecraft assembly, integration and test. Because, it is necessary that a operator of a ground station controls the precise positions of on-orbit spacecraft by using the alignment data of attitude orbit control sensors(AOCS) on spacecraft. And, an accuracy of spacecraft alignment requirement is about $0.1^{\circ}{\sim}0.7^{\circ}$. A spacecraft alignment is measured by autocollimation of theodolite. This paper describes the measurement principle and method of spacecraft alignment. The result shows that all the AOCS on the spacecraft are aligned within the tolerance required through the alignment measurement.

Results Analysis for On-orbit Operation of KOMPSAT-1 Propulsion System (다목적실용위성 1호 추진시스템 궤도운용 결과 분석)

  • 김정수;한조영;진익민
    • Journal of the Korean Society of Propulsion Engineers
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    • v.4 no.4
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    • pp.107-113
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    • 2000
  • Design configuration and performance requirements for KOMPSAT-1 propulsion system were described. Operational results of the propulsion system obtained through the satellite Launch and Early Operation Phase were scrutinized. Performance characteristics of the thrusters which are employed for spacecraft attitude control and the corresponding propellant depletion rate were analysed according to satellite operation modes. Additionally, propellant leakproof and thermal control capability were checked out from the view point of system verification. Propellant depletion rates calculated by PVT method in $\Delta$V maneuvering and each attitude control mode produce the very meaningful results for the prediction of total propellant consumption up to the end of satellite mission life.

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병렬기구의 개발현황

  • Cha, Yeong-Yeop
    • ICROS
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    • v.15 no.1
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    • pp.22-28
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    • 2009
  • 병렬기구는 조립, 포장, 기계가공, 크레인, 수중공학, 항공 및 해양구조, 비행 및 3D 시뮬레이션, 위성 접시안테나 위치제어, 망원경 자세제어, 그리고 정형외과 수술 등 여러 분야에 사용되고 있다.

저궤도 위성 열진공 시험의 전자 시험 설계

  • Gwon, Dong-Yeong;Jeon, Mun-Jin;Lee, Na-Yeong;Kim, Dae-Yeong
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.2
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    • pp.170.2-170.2
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    • 2012
  • 위성의 열진공 환경 시험은 고진공 극저온의 우주 환경을 모사하여 열제어 기능 및 임무 수행 능력을 검증하는 시험이다. 이 시험에서는 위성 주위에 부착한 방열판으로 위성 외각 온도를 변화 시켜 위성의 태양 지향 자세 또는 심우주 지향 자세를 모사하며, 이에 따른 위성의 온도 변화에 따라 지상 시험 장비로 위성의 히터 설정, 유닛 전원 형상의 변경 등을 해야한다. 또한 극고온 또는 극저온의 환경에 장시간 연속적으로 노출된 상태에서 위성의 기본적인 기능부터 영상 미션까지 검토하는 CPT 시험을 수행하며, 이 CPT 시험은 극한의 위성 상태의 시험이기 때문에 온도를 고려한 전자 시험 설계 및 24시간 위성 모니터링 시스템, 위험상황 발생 시 대처 방안 등에 대한 준비가 필요하다. 본 논문에서는 열진공 시험 시의 전자시험의 형상과 설계에 대해서 설명하고, 시험 결과에 대해서 정리하였다.

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Attitude Controller Design for a Bias Momentum Satellite with Double Gimbal (더블김벌을 장착한 바이어스 모멘텀 위성의 자세제어기 설계)

  • Park, Young-Woong;Bang, Hyo-Choong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.32 no.4
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    • pp.34-42
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    • 2004
  • In this paper, a double gimbal is used for roll/yaw attitude control of spacecraft and two feedback controllers are designed. One is a PD controller of no phase difference between roll and yaw control input. The other is a PD controller with a phase lag compensator about the yaw control input. The phase lag compensator is designed a first order system and a lag parameter is designed for the control of yaw angle. There are two case simulations for each of controllers; constant disturbance torques and initial errors of nutation. We obtain the results through simulations that a steady-state error and a rising time of yaw angle are developed by the compensator. In this paper, simulation parameters use the values of KOREASAT 1.

Radial Type Satellite Attitude Controller Design using LMI Method and Robustness Analysis (LMI 방법을 이용한 방사형 인공위성 제어로직 설계 및 강건성 분석)

  • Rhee, Seung-Wu
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.43 no.11
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    • pp.998-1007
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    • 2015
  • The $H_{\infty}$ control theory using LMI method is applied to design an attitude controller of radial type satellite that has strongly coupled channels due to the large product of inertia. It is observed that the cross-over frequency of open-loop with $H_{\infty}$ controller is lower than that of open-loop without controller, which is not typical phenomenon in an optimal control design result: it is interpreted that due to a large product of inertia, there is certain limit in increasing agility of satellite by just tuning weighting function. ${\mu}$-analysis is performed to verify the stability and performance robustness with the assumption of +/-5% MOI variation. ${\mu}$-analysis result shows that the variation of principal MOI degrades the stability and performance robustness more than the variation of POI does.