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
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$\begingroup$ That is both dependent on your control design, your actuator capabilities and sensor accuracy and availability. Supposing you have star sensor, with continuous updates, one is pretty much limited by then actuator, for example wheels jitter. $\endgroup$ – Prakhar Aug 11 '20 at 4:57
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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.
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$\begingroup$ Your link to the attitude determination primer doesn't work for me. I get a page of XML. If you can come up with a good link, I suggest you add it to the resources page on meta - we get a ton of cubesat attitude control questions. space.meta.stackexchange.com/questions/249/… $\endgroup$ – Organic Marble Aug 17 '20 at 20:27
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1$\begingroup$ I see what happened, you got bitten by the NASA NTRS redesign just like I did a while back. I edited in what I think is the correct link, please revert if it wasn't. When one clicks on the new NASA NTRS links, it opens in some kind of goofy URL that doesn't work when cut and pasted. You have to copy the download link and use that instead. $\endgroup$ – Organic Marble Aug 17 '20 at 22:57
