Help with adding Exoskeleton to Rajagopal Model

[Emily Klinkman]

Hi everyone,

I am trying to add bilateral active ankle exoskeletons to the Rajagopal 2015 model, in order to run IK, ID, and Static Optimization from experimental data. I'm adding the exo direcly into the .osim file.

I've added the exo frame geometry as an object under <BodySet> with an attached .stl file and now the model won't open in the GUI. I get the following errors:

(1) Attempting to assign an invalid StimTK::MobilizedBodyIndex in Object 'pelvis_offset' of type PhysicalOffsetFrame. Thrown at PhysicalFrame.cpp:73 in setMobilizedBodyIndex()
(2) Body 'exo_r' not connected by a Joint.A FreeJoint will be added to connect it to ground

Has anyone experienced the same errors and know what I'm doing incorrectly? I'm assuming I need to specify a joint to connect the exo to the ankle but I'm not sure where to put it. Thanks in advance! Happy to connect via email and send my .osim files.
See below for snippet of .osim:

OSIM_screenshot.png (58.18 KiB) Viewed 502 times

[Mohammadreza Rezaie]

Hi, your assumption is correct. The error is due to lack of any connection to your exo. It seems that OpenSim's automatically defined a joint between the exo and the ground.

Joints are specified in JointSet. Use hip_r joint as a reference to define a new joint between foot(?) and the exo bodies (Simply copy and paste it and then, adjust it). You can have 6 degrees of freedom (Dof) between bodies in CustomJoint, or no DoF in WeldJoint. Please see:
https://simtk-confluence.stanford.edu:8 ... JointTypes
https://simtk.org/api_docs/opensim/api_ ... ml#details

[Mahshida hamid]

Hey, did you find the error. I am actually stuck in a similar problem too.