bug fixes in v2.1 address knee_angle and wrap visibility

[Edith Arnold]

Two bugs in the 2-leg, OpenSim version of the lower limb model were recently brought to my attention, and I have posted a new version to correct these issues. v2.1 is now available for download. The
bugs and fixes are:

Bug: The range of the knee_angle_r and knee_angle_l coordinate was inappropriately increased from 0-100 degrees to 0-120 degrees in one of the posted model versions. I was working with this range in a research version of the model and did not intend to post it publicly. This model was only validated for a range of 0-100 degrees (see the publication affiliated with the project) and the increased range introduces errors in muscle geometry.

Fix: In the short term, I have reverted the range of motion to 0-100 degrees in version 2.1 To avoid invalid regions of muscle geometry please download the new version.
If you have already made modifications to the model that you'd rather not have to re-do, reduce the range directly in your files. This is done by changing two lines. Under <Coordinate name="knee_angle_r"> and <Coordinate name="knee_angle_l"> replace this:
<range> 0.00000000 2.09439510 </range>
with this:
<range> 0.00000000 1.74532925 </range>

Reload the model and check that the coordinate slider in the GUI goes from 0-100 degrees.

In the long term, I am making several changes to the model to make it appropriate for higher knee flexion applications and will share this when I have validated it. There will then be two versions of the
model available, the lower flexion one that is aligned with the publication and a higher flexion version which will be documented on the project page. Check back in a few months for this.

Bug: Wrapping surfaces were showing up as shaded, even after hiding them in the GUI and re-saving the model.

Fix: I have changed the display preferences code for the wrapping surfaces. I think this was a problem introduced when converting the model between versions of OpenSim. If you'd like to correct it
directly in your models find the VisibleObject lines under each wrap surface and replace this:
<VisibleProperties name="">
<display_preference> 0 </display_preference>
<show_normals> false </show_normals>

<material_name> DEFAULT </material_name>
</VisibleProperties>

with this:
<display_preference> 0 </display_preference>


Please let me know if you have any questions about these changes.

-Edith