Attitude control with magnetorquers

[Daria Andrievskaia]

Hi Basilisk people,

I'm working on a cubesat model, which ADCS is solely magnetorquers and magnetometers. Among the BSK tutorials there are ones describing how to use magnetic torque bars (MTB) along with reaction wheels to drive the net angular momentum of the RWs to zero for example. I am wondering is it possible to use only MTBs for attitude control?

Thank you!

Regards, Daria

[benjamin....@u-space.fr]

Hello Daria, 

MTBs can generate a magnetic moment vector in any direction in the spacecraft body-frame, with a maximum magnitude dictated by the saturation capacity of the individual coils or rods. This magnetic moment m interacts with the Earth magnetic field B and subjects the spacecraft to an external torque given by cross(m,B). As a result, it is impossible to produce a magnetic torque in a direction that is colinear to the magnetic field. 

This is why you cannot achieve generic 3-axis control with MTQs alone, because there always is a direction about which it is impossible to produce an instantaneous torque.

Cheers, 

Ben

[Hanspeter Schaub]

As Ben says, you can do 2D attitude control.  There are solutions that converge over many orbits as the 2D plane where you can apply torques varies over the orbit with the local magnetic field direction.  We don't have such a module in BSK yet.  You would have to create your own.

[Daria Andrievskaia]

Thank you for your response Ben!

среда, 4 мая 2022 г. в 20:39:07 UTC+2, benjamin....@u-space.fr:

[Daria Andrievskaia]

Thank you prof Schaub! Will try to do so

четверг, 5 мая 2022 г. в 04:07:37 UTC+2, hanspete...@colorado.edu: