Two ellipsoid muscles

[Lukuas31415]

Main changes of this PR

Issues that are addressed by this PR:

Features that have been added:

Additional information

Author's checklist

• I updated the documentation.
• I checked that everything compiles and runs as it should.

[carme-hp]

Hi Lukas, can yo look into this error?

Error: Traceback (most recent call last):
  File "<string>", line 179, in updateNeumannContraction_1
NameError: name 'tendon_end_t' is not defined

[Lukuas31415]

Hi Lukas, can yo look into this error?

Error: Traceback (most recent call last):
  File "<string>", line 179, in updateNeumannContraction_1
NameError: name 'tendon_end_t' is not defined

I haven't gotten this error so far. But I still added the variable in the beginning of the file, so this shouldn't be an issue now.

[Lukuas31415]

@carme-hp, I have a question: What do you think about the following plot of the lengths of the ellipsoid muscles with the spring-tendon simulation (only muscle 2 is being activated)? Until 70ms it looks great, but after that the second muscle is contracting again, but it's not being activated again, and the first activation has gone through the entire muscle already.

And this is the plot for the direct connection of the muscles. It seems to be extremely unstable (in paraview it looks a bit wonky as well). This simulation has to be fixed before merging.

[carme-hp]

How does the direct connection look like in paraview? I think it could lead to the muscles overlapping.
That the direct comection is unstable is expected.
The first plot looks good! Could be that because the muscle is a hyperelastic material it contracts again due to spring behaviour, but i'm not sure about it.

[Lukuas31415]

The muscles of the direct connection are not overlapping, but that could easily happen with slightly different parameters. This is a screenshot from this simulation in paraview. It does not capture the wonkyness well, because it's also the process that's weird. It is very jittery and doesn't behave as expected at all.

Another weird thing is the beginning of the simulation. The first 40ms seem to work fine, but at 20ms, the first muscle is contracting again, even though the second muscle is still contracting. Can that also be explained, or is the simulation not working at all times?

[carme-hp]

Are you sure about 2+? I'd expect that the muscle in the left uses 2- and the one in the right uses 2+.

[Lukuas31415]

I thought so too, but after looking at the result in Paraview, I was sure this had to be 2+ in both cases, because this is the only case where the connection looks reasonable.

[carme-hp]

Okay, then we keep it like this but lets open an issue about this

[carme-hp]

Ready to merge!