SOFA - Extracting reaction forces from a collision

[satimmer]

Hi

I am currently working on a model to simulate the behavior of soft robotic actuators.
The goal of the simulations is to compare the forces applied on a flat and inclined
surface in order to quantify the force loss due to side wards deformation of the actuator.
Therefore I would like to extract the force vectors of the flat or inclined object in order to
compare the forces applied in the x direction.

On the SOFA forum, I have already found some related topics, but the answer is still
unclear to me. As the force vector can not be extracted directly from the mechanicalObject,
I have taken a look at the following topic in order to compute the forces using the Lagrange
multipliers: https://www.sofa-framework.org/community/forum/topic/getting-forces-generated-by-a-collision/#post-14171 .
Unfortunately, I am not really familiar with adapting the source code of software, so I was
wondering if someone could explain a bit further this implementation in c++ of the
mechanicalObject code and the ConstraintProblem and where I can find these values
after implementing this code?

In attachement I have also added the python script I am currently using to do the simulations.

Thank you in advance!

Kind Regards
Sander

Flat_BSPA_9_sections.zip

[hugtalbot]

Dear @satimmer
Welcome!
Have you looked at the following discussion?

[satimmer]

Dear @hugtalbot
The problem has been resolved by running the scene in a newer version of SOFA. Hereby, I have put the topic as resolved
Kind regards
Sander Timmermans

[hugtalbot]

Hi @satimmer
Sorry, I was not able to find more time to share updates with you earlier.
But I am really glad to read that you solved it ! thanks a lot for getting back to us!

[ChangjingLiu]

Dear @hugtalbot The problem has been resolved by running the scene in a newer version of SOFA. Hereby, I have put the topic as resolved Kind regards Sander Timmermans

Thanks. I have the same problem. Which version of SOFA you are using?

[ChangjingLiu]

Thanks, I solved it.
The force can be obtained by using “.value” method, like the following format in onAnimateBeginEvent
print(self.GenericConstraintSolver.constraintForces.value)

[satimmer]

Exactly, that is how I am extracting it as well. Remember to do the calculations as explained in this link: https://www.sofa-framework.org/community/forum/topic/getting-forces-generated-by-a-collision/#post-14171 .
I was first working with version 19.06 and it is now working on version 21.12.