Understanding contact modeling and parameters

[bilal-bdai]

I'm currently using the model builder to set up a humanoid simulation from a given URDF file. When I print model.rigid_contact_max, I receive the value 212852, and I suspect that this high number of contact points may be contributing to the simulation's slow performance.

I have a couple of questions regarding the collision model:

Contact Point Limitation:
Is there a way to limit the number of contact points per mesh during collision checks?

Contact Model Details:
While tracing the code, I noticed that eval_rigid_contacts appears to implement a classical linear spring-damper model. Is this model used when a robot makes contact with the ground, or is it solely for mesh-mesh collision computations? Also, is there an alternative approach available—perhaps a complementarity-based method? I'm exploring this because stiff visco-elastic contacts often require very fine integration time steps, which can introduce significant computational overhead.

Any guidance on tuning the simulation or adjusting the model for more realistic behavior and better performance would be greatly appreciated.

Thank you in advance for your help!

[shi-eric]

@eric-heiden can you help?