Drop Landing Model

[Jiang Ping]

Hi all,

I am trying to add a contact force to the foot. I think that "Drop Landing Model" will be a good example, but I don't have the access to see the source code. Is there any chance for me to see it?

One more question, why several sepheres were added to the model as contact geometry instead of adding the mesh geometry of foot by converting VTP. files to OBJ. files?

thanks,
Jiang

[Jennifer Hicks]

Jiang -

You can see an example of how to specify contact in the BouncingBlock model that we distribute with OpenSim.

The drop landing model was intended as a demonstration model only. It's representation of foot-floor contact has not been validated in a research setting (e.g. the placement of the contact spheres on the foot were not carefully tuned).

Best wishes,
Jen

[Jiang Ping]

Hi Jen,

Thanks for your reply. I saw the example and tried to add ElasticFoundationForce to the model as contact force. It works well, but when I changed the force type to HuntCrossleyForce, it didn't work. The model penetrated into the ground.

What's the difference between ElasticFoundationForce and HuntCrossleyForce? How to specify HuntCrossleyForce properly?

thanks,

Jiang

[Nokhez Qazi]

Hi Jiang,

Could you please post any updates or results you recieved. Did the HuntCrossleyForce work? Were you successful with converting .VTP files to .OBJ files? How did u make them water tight? Kindly update me as I am running into these same issues.

So far, I have converted .VTP to .STL using Paraview, then using MeshLab, I converted the .STL file to .OBJ file. Some .VTP files get converted pretty well to .OBJ files (eg. l_femur), however it is not watertight, or there is some other issue since it just falls through the contact half space even with a really high stiffness value for the HuntCrossleyForce. Please update on your progress.

Thanks,
Nokhez

[Jiang Ping]

Hi Jiang,

Could you please post any updates or results you recieved. Did the HuntCrossleyForce work? Were you successful with converting .VTP files to .OBJ files? How did u make them water tight? Kindly update me as I am running into these same issues.

So far, I have converted .VTP to .STL using Paraview, then using MeshLab, I converted the .STL file to .OBJ file. Some .VTP files get converted pretty well to .OBJ files (eg. l_femur), however it is not watertight, or there is some other issue since it just falls through the contact half space even with a really high stiffness value for the HuntCrossleyForce. Please update on your progress.

Thanks,
Nokhez

if you try to use .obj files for contact geometry, you should use elasticfoundationforce instead of HuntCrossleyForce