Introducting friction to catheter procedure simulation

[MarkWrobelUCL]

Hi all,

I am trying to simulate a catheter procedure in a heart vessel. My code can be found here: https://github.com/MarkWrobelUCL/SOFA/blob/main/PA_cath_sim_2.py

My main issue is that I am trying to increase the friction (or introduce friction) between my catheter and vessel. Line 70 has CollisionResponse added with mu=10 to make it obvious if there is a change. I am not sure why this is not working. I have read a precious thread (https://www.sofa-framework.org/community/forum/topic/the-friction-between-a-tissue-and-a-surface/) and added things like UncoupledConstraintCorrection on lines 116 and 127 to no effect.

The only thing I can think of is that my vessel has a HexahedronFEMForceField but I'm not sure my catheter has an analogous object. When I try adding BeamFEMForceField on line 104 it crashes my code.

I would appreciate any help and Ideas as I am quite stuck at this point.

Thanks, Mark

[hugtalbot]

Hi @MarkWrobelUCL

To build a simulation with frictional contact solved using Lagrange multipliers, what is needed is:

• one FreeMotionAnimationLoop ✔️
• only one constraint solver in the root node (LCP is a good choice for contact) ❌
• define the collision response as response='FrictionContactConstraint' ✔️
• each object (mechanical representation of it) must one (only) ConstraintCorrection ❌

Therefore, you can remove:

• this
• and this

and you should make sure to define a defaultCompliance in the UncoupledConstraintCorrection of your blood vessel (if you do not know what value to set, I advise to set the inverse of the vertexMass value in your associated UniformMass)

Hope this helps

[MarkWrobelUCL]

Hi @hugtalbot,

Many thanks for your reply. I have made changes to the code as you have suggested, however it still does not behave as expected https://github.com/MarkWrobelUCL/SOFA/blob/main/PA_cath_sim_2.py.

I set the defaultCompliance to the inverse of the vertex mass however, I do not know what value of vertex mass I should use. At high vertexMass the simulation behaves normally but still has no friction. At low vertex mass the catheter seems to not interact with the vessel at all.

I would appreciate any further help you can give.

Thanks, Mark

[beamadapter]

I am involved in lung intervention and also want to create friction and deformation. Can I communicate with each other? Do you have a WeChat account?

[hugtalbot]

Hey @MarkWrobelUCL
Sorry for popping only now: we now setup a system to carefully watch unsolved topics.
Do you still need any assistance from us?

@beamadapter could you share some updates/achievement of your work? feel free to share here

[github-actions[bot]]

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@MarkWrobelUCL
Feedback has been given to you by the project reviewers, however we have not received a response from you. Without further news in the coming weeks, this discussion will be automatically closed in order to keep this forum clean and fresh 🌱 Thank you for your understanding