1 set of external vs 2 sets of external loads

[Anthony Kulas]

Hello,
I am currently using model 2392 for a single leg squat task. I am able to scale the model and run the inverse kinematics tool which also correctly shows the GRFs for the right leg. However, since there is only one set of external loads (right leg only, not left leg), the RRA tool is interrupted with an error of:
FowardTool.run: ERR- Column index for left ground_force_vx not found
I have searched through the XML files and tried to change the calcn_l to a blank but with no success. Is there somewhere in the code that I have overlooked where I can change OpenSIm RRA to only "look" for one set of external loads? Thank you.

[Ayman Habib]

Dear Anthony,

As of now the code expects two sets of external forces. We're aware of this, serious, limitation and will have a fix for it later in the summer (release 2.0) For the time being however, as a work around, you may want to add a set of columns with 0 value for the missing columns.

Best of luck,
-Ayman

[Samuel Dyson]

Hi,

Just wondering if this issue has been resolved yet? It still appears that OpenSim requires forces for the left and right foot.

[Ayman Habib]

Hi Samuel,

OpenSim stopped requiring this since version 2.0.2. You should be aware, however, that running RRA, CMC or ID tools require that you have all the forces being applied to the model. For example in the case of gait, if you have data from one force plate/foot-strike then you can only run RRA/CMC/ID for that part of the gait cycle.

Hope this helps,
-Ayman

[Samuel Dyson]

Thanks Ayman, appreciate all your help