simtk.org

Hi all,
The current gait2392 model has only one Dof for the knee. The tx and ty are functions of the knee flexion angle. I am wondering if anyone develop a model which allows that the movements of the 6 DOfs of the knee are precribed.
I tried that. but once I made the tx and ty indepedent, after scaling, the bone looks unrealistic. Does any have experience on that?
Thanks in advance.

Kang

Kang
Have you received any feedback about a model using 6 DOFs for the knee?

Mike

I did not receive any response yet.

Kang,

Did you get 6 sliders for the 6-dof at the knee with your modified model? If so and they exhibit the correct motion then never mind the bone geometry, it's just used for visualization.

-Ayman

Thanks. When I creat the knee joint with 3 translational DOF, the visualization becomes awkward after scaling.

Kang,

If there's a specific visualization problem, please report a bug and attach the model and we'll check it out and let you know..

Thanks
-Ayman

Ayman,

I have reported a bug and attach the model and other necessary files .

Thank you for your help in advance. If this is not a bug, please also let me know

Kang,

The extra DOFs look just fine.

I see the model looking funny with disconnected knee after scaling but that's exactly what happens when you give the optimizer (used to move markers) these knobs to work with. It would do anything to reduce marker error and the translations at the knee are not different from any other knobs.
Things that may help:
- Limit the range for the translations at the left knee.
- Shorten the range of the .trc file used for scaling (model should be almost static, otherwise the averaging of frames makes no sense)

Just keep in mind that you'll run into the same issue of the knee disconnecting during IK, and later unless you lock, prescribe or otherwise constrain the translation coordinates you introduced at the knee.

Good Luck,
-Ayman