• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.371-378
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• 2019

High precision pointing satellite uses the reaction wheels for the attitude control and their momentum dumping is performed by the three magnetic torquers. In this paper, the effects of one magnetic torquer's failure on the momentum dumping will be reviewed. When the satellite on the high inclination angle orbit holds LVLH (Local Vertical Local Horizontal) attitude, pitch axis magnetic torquer failure causes the momentum dumping failure. But in case of other torquer's failure, momentum dumping is still possible with degraded dumping performance. When pitch axis magnetic torquer fails, momentum dumping is possible by changing the satellite attitude. This paper propose the satellite attitude change to make the momentum dumping possible when pitch axis magnetic torquer fails. In addition, if torquer arrangement is modified, momentum dumping is always possible regardless of any torquer's failure.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.147-158
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• 2020

In this paper, we will review the thruster based reaction wheel momentum dumping method for low Earth orbit satellite. Thruster based momentum dumping is widely used in GEO satellites by performing momentum dumping and attitude control using thrusters at the specific time. LEO satellite should perform momentum dumping at any time, thus it is not appropriate to use GEO satellite's momentum dumping method. In this research, we will review the method for LEO satellite, which perform momentum dumping always and use reaction wheels for attitude control during dumping. To reduce thruster's valve on and off counts, we propose to use the maximum pulse width for thruster operation. To prevent attitude error increase by thrusters, we adjust the thruster operation interval. Through simulation, we verify the proposed method's effects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.9
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• pp.81-88
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• 2005

This paper analyzes the fuel consumption for the momentum dumping of the COMS which has a single solar array system. First, numerical analyses are conducted to find an optimal momentum dumping time considering the COMS configuration. It is assumed that the momentum dumping is conducted once a day and at a fixed time of a day. Secondly, in an effort to reduce the momentum dumping fuel consumption, this paper proposes a new approach which combines the momentum dumping and the ordinary north/south stationkeeping. Finally, to evaluate the proposed technique, the stationkeeping simulations are conducted and analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.760-766
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• 2018

Due to external disturbances on the satellite, unwanted momentum is accumulated on reaction wheels. To remove this momentum, three magnetic torquers which are installed along the satellite's axes are used. The magnetic torquers generated torque indirectly by interactions with the earth's magnetic field. Thus, during momentum dumping, we should consider both the magnetic torquer and the earth's magnetic field generated on the magnetic torquers at the same time. When low earth orbit satellite with high inclination angle holds nadir pointing attitude, weak earth's magnetic field is generated along the satellite's pitch axis. In this case, one magnetic torquer is overloaded and momentum dumping performance is degraded. This research will review the method to improve the momentum dumping performance by adjusting magnetic torquers arrangement.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.85-94
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• 2003

A geosynchronous Satellite in general, has two momentum management logics to maintain its wheel momentum tin the stable region. The one is applied in order to control accumulative wheel momentum in the momentum dumping mode and the other is utilized in order to control attitude errors during the stationkeeping. In this paper, the momentum management logics are explained for dumping/sationkeeping mode and the logics are verified by simulation on the 3 attitude subsystem.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.193-200
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• 2011

The external disturbance torque acting on a low earth orbit spacecraft was analyzed. For the Earth pointing attitude, the maximum torque to the spacecraft is about $8.3{\times}10^{-4}$ Nms and the momentum accumulated for an orbit is about 1.4 Nms and for the Sun pointing attitude, the maximum torque to the spacecraft is about $1.6{\times}10^{-3}$ Nms and the momentum is accumulated about 3.0 Nms in the spacecraft body reference frame. The analysis results confirm that the size of magnetic torquer selected previously for the satellite is sufficient to manage the accumulated momentum by considering the dumping capacity for an orbit.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.245-250
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• 1998

Attitude determination and control of satellite is important component which determines the accomplish satellite missions. In this study, attitude control using reaction wheels and momentum dumping of wheels are considered. Attitude control law is designed by Sliding control and LQR. Attitude maneuver control law is obtained by Shooting method. Wheels momentum dumping control law is designed by Bang-Bang control. Four reaction wheels are configurated for minimized the electric power consumption. Wheels control torque and magnetic moment of magnetic torquer are limited.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.285-286
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• 2014

• Bulletin of the Korean Space Science Society
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• 2005.04a
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• pp.133-137
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• 2005

This paper describes the design and performance verification of a pitch momentum bias control system being built by students at the Space System Research Laboratory(SSRL). HAUSAT-2 ADCS(Attitude Determination and Control of Subsystem) op-elation mode is divided into two parts, initial mode and on-orbit mode. This paper describes design of the HAUSAT-2 performance of attitude control results using pitch momentum bias control method in initial mode and on-orbit mode and momentum dumping method.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.115-118
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• 1995

This paper present an attitude control using quaternions as feedback attitude errors. The Euler's eigenaxis rotation provides the shortest angular path between two attitudes. This eigenaxis rotation can be achieved by using quaternions since quaternions are related with the eigenaxis. The suggested controller uses error quaternions and body angular rates and generates a decoupling control torque that counteracts the natural gyroscopic coupling torque. The momentum dumping strategy using the earth magnetic field is also applied in this paper to unload the angular momentum of the reaction wheels used in the attitude control.