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Hi OpenSim Team,

I am currently trying to implement contact forces for my model, and I have looked at the tutorial covering it with the bouncing ball and ellipsoid; however, I am trying to implement contact forces that allow my model to remain still on the ground. I don't want to weld my model onto the ground because I want it to be able to traverse the ground following a rectilinear motion. Is there a specific force type I should use or property value I should tweak in order to have contact forces on my model without a bouncing motion?

I want it to be able to traverse the ground following a rectilinear motion

You could attach your model to Ground via a SliderJoint (https://simtk.org/api_docs/opensim/api_ ... Joint.html) or constrain it using a PointOnLineConstraint (https://simtk.org/api_docs/opensim/api_ ... raint.html).

Thanks for the suggestions, but is there anyway to remove the bouncing force from the huntcrosselyforce? I would ideally like to use contact spheres for the points on my model that make contact with the ground.

is there anyway to remove the bouncing force from the huntcrosselyforce?

You could increase the dissipation coefficient. Please see Section 11.2 in the Simbody theory manual: https://github.com/simbody/simbody/tree ... imbody/doc.

Increasing the dissipation coefficient seemed to help, but the model I have slowly tilts forward when I run an in-place motion, a motion that should allow the model to remain standing still. Also, I have decided to use contact meshes for the model as opposed to contact spheres to see if it would make a difference, but I still experience the same issue of having my model tilt forward.

Do you have any suggestions on how I can have my model remain standing still without bouncing or tilting forward using contact forces? For example, if the object in the bouncing ball tutorial was instead a bouncing cube, would it be possible to remove the bouncing motion and simply have the cube sitting up straight without falling over.