Sun Pointing Attitude Control with Magnetic Torquers Only
- Paper number
IAC-06-C1.2.01
- Author
Dr. Huaizu You, National Space Organization, Taiwan, China
- Coauthor
Dr. Ying-Wen Jan, National Space Organization, Taiwan, China
- Year
2006
- Abstract
Satellite tumbles after it is separated from the rocket and the tumbling might happen when any contingency or anomaly occurs. During this Acquisition and Safe Hold (ASH) mode, it is required that the satellite consumes the least power due to the fact that most satellites use photovoltaic cells to sustain their power and heat, and that the battery has limited capacity. Therefore, it is necessary to maneuver the satellite to sun pointing attitude using the least actuators within a tolerable period of time. In this paper, a small satellite, Argo, is analyzed. Argo satellite, developed by National Space Organization (NSPO), Taiwan, will join the German-based RapidEye constellation and serves the remote sensing mission in 2008 to provide agricultural and cartographic information, and it has a near-circular sun-synchronous low-Earth orbit (LEO).
Using actuators merely from magnetic torquers without reaction wheels to perform three-axis active attitude control for a small satellite in a sun-synchronous, low Earth orbit is achievable, in conjunction with sensor suite comprising magnetometers and omni-directional sun sensor. The spacecraft angular velocity is estimated based on sensor information from both magnetometers and sun sensors. The omni-directional sun sensor provides a global field of view of the sky so as to enhance the chance of acquiring the sun during satellite tumbling state. The control law is based on spacecraft dynamics: the command torque profile switches between B-dot law, which damps rates but cannot accomplish three-axis attitude pointing, and sun alignment torque, which compensates the sun vector attitude pointing error and maneuvers the satellite orientation such that the zenith direction is facing the sun. The switch timing depends on whether the spacecraft angular momentum has less than 80
- Abstract document
- Manuscript document
IAC-06-C1.2.01.pdf (🔒 authorized access only).
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