Issue with Physical offset frame in v4.1

[Alex Noakes]

Hi,
I'm trying to convert the Caruthers et al sit to stand model from the v3.3 to v4.1 of OpenSim and I'm having an issue with the offset of the pelvis. The interface gives me an error saying "Attempting to assign an invalid SimTK::Mobilizedbodyindex. In object 'pelvis_offset' of type PhysicalOffsetFrame. Thrown at PhysicalFrame.cpp:37 in setMobilizedBodyIndex()." I'm unable to find the item pelvis_offset and therefore cannot understand the issue. Thank you for your help!
Kind regards
Alex

[Ayman Habib]

Hi Alex,

Please post a link to the model (as it is not a model that we regularly distribute/maintain), so we can check it out.

Best regards,
-Ayman

[Alex Noakes]

Thank you for responding. The link for the model is below.
https://simtk.org/projects/osufullbody_sts
Cheers
Alex

[Ayman Habib]

Hello,

The download link states that the model is compatible with version 3.3 so I'm not sure what updates you need to make so it works in version 4.0+ however attempted loading of the model fails due to:
BodySet 'bodyset' has subcomponents with duplicate name 'radius_l'. The duplicate is being renamed to 'radius_l_0'.
JointSet 'jointset' has subcomponents with duplicate name 'sternoclavicular'. The duplicate is being renamed to 'sternoclavicular_0'.
JointSet 'jointset' has subcomponents with duplicate name 'radioulnar_l'. The duplicate is being renamed to 'radioulnar_l_0'

Renaming the bodies/joints causes downstream effects as bodies are not found. We didn't enforce the name uniqueness pre 4.0 but you should manually change the names in the osim file to be unique before attempting to load the model, also a long list of coordinates have inconsistent type which should be fixed according to the release notes of version 4.0.

Hope this helps,
-Ayman

[Alex Noakes]

Okay, thank you for you help. Is there any way to download the older 3.3 version of open sim so that I can bypass having to change the code in the model?
Kind regards
Alex

[Thomas Uchida]

Yes- older versions of OpenSim are available on the SimTK project page (https://simtk.org/projects/opensim; click "Downloads" at the top and then expand the "Previous Releases" section under "OpenSim 4.1").