Pointing accuracy and relevant manoeuvers CUBESAT

Question

How do you calculate or determine the pointng accuracy of your CUBESAT in sunlit-part and eclipse-part modes? Also how do you determine the maximum roll/pitch/yaw angles and slew rate required in relevant manoeuvers?

Thank you

Answer 1

There is nothing special about the attitude control of a CubeSat compared to any other satellite. CubeSats just have more stringent size/mass/power constraints which might limit some of your options.

For the determination simple CubeSats rely on Coarse Suns Sensors (CSS) or even on the voltages from their solar panels. Magnetometers are also common, especially to implement simple detumbling algorithms. More elaborate control systems will use gyros (Inertial Measurement Units) and star trackers for increased accuracy.

Sensor data can be used raw, or more commonly, fed into a filter such as a Kalman Filter.

Maximum Pitch/Roll/Yaw angles are purely dependent on your mission, as usually there is no physical limitation on what attitude the satellite may point while in space. Any limits usually derive from constraints such as not pointing a camera at the sun or pointing the telescope to deep space.

The maximum slew rate is limited by how big your actuators (torquer bars, reaction wheels, thrust) are relative to your satellite. Or conversely, if your mission requires as specific slew rate, that would drive the size of your actuators.

NASA has published a good primer for students on Attitude Determination for CubeSats.

I also would strongly recommend you start by reading some books on the subject:

• The Classic: Wertz, Attitude Determination and Control
• Chobotov, Spacecraft Attitude Dynamics
• A more modern text: Yang, Spacecraft Modeling
• Many others on Amazon.