Aerodynamic disturbances

[GabrieleMeoni]

Description

Summary of changes:

• Created new function calculate_aero_torque that calculates the aerodynamical torque on the satellite under the hypotesis that the satellite is described by a cuboid mesh, as it is as of now (see geometrical model). The model only works for Earth as a central body as of now. The model is based on the aerodynamical parameters calculation presented in"Roto-Translational Spacecraft Formation Control Using Aerodynamic Forces", Ran S. et al. , JOURNAL OF GUIDANCE, CONTROL, AND DYNAMICS, 2017.
• Implemented this function in the function calculate_disturbance_torques in attitude_model.py
• Created pytests for this additional code

Resolved Issues

• fixes Aerodynamic disturbances in Attitude Model #197

How Has This Been Tested?

Two types of tests have been created in order to verify and validate the function:

1. Real word comparison with GOCE data. The satellites perturbations in the same orbit as GOCE shall have the same order of magnitude of reported GOCE perturbations.
2. Corner cases: in three cases has been evaluated the torque resulting from a simple 1-axial rotation of the satellite which resulted in a predictable torque direction or in no torque at all.

Related Pull Requests

None, attitude model not used in development nor tests.

[GabrieleMeoni]

@GiordanoNesci. The model looks good, but this code shows poor integrability with PASEOS. You also did not create a PR.

Please, make also sure that you merge the last student branch

[GabrieleMeoni]

There is a thermal model, this is completely disconnected.

[GiordanoNesci]

There is the possibility to treat the temperature as an input from the thermal model (when the latter is used). As of now the temperature of the spacecraft is treated as a constant, since the model is not sensitive to the temperatures.

[GabrieleMeoni]

Ok, thanks.

[GabrieleMeoni]

This shall be an input or a property of the central body.

[GabrieleMeoni]

As above.

[GiordanoNesci]

The model is almost ready to merge, but there are some minor things to fix:

• Gas temperature and densities shall be moved to be properties of the central body, or inputs
• The temperature of the spacecraft could be retrieved with the thermal model when it is used in the simulation

I do not know if there are any steps missing to make it implementable in the attitude model (e.g. if there is the need to get the mesh from the geometric model, to the attitude model, to the disturbance functions).