simtk.org

Hi,

I ran ID for a right leg model and one including both legs, and got different moments for the hip, knee and ankle. The curve trends are pretty much the same, but magnitudes change. The IK data only contains GRF for the right leg. Does anybody know why this could be happening?

Thanks,

Daniel

Hi Daniel,

If I understand your two cases correctly, I would
expect different ID moments for them. If your
right leg model has no torso, etc., then I'd
expect the ID moments to be incorrect (one reason
being that the ground-reaction forces are from
a full body). For the two-leg model (does this
one include a torso?) I'd expect the ID moments
to be incorrect when the left leg is in contact
with the ground (because there are no left-leg
ground-reaction forces) and incorrect for all
frames if the model does not have a torso.

But since the models include different body
segments and have different masses, the ID
results should be different with the same IK
input.

Regards,
Peter