Issues creating scaling model with new marker set w/ tracking markers

[AUDE LEFRANC]

Hello Everyone!

I'm very new to openSim, so apologies if this is a silly question.
I'm using openSim 4.0. I have been trying to create/adjust a model using a static trial with a slightly different marker set. I open up a built in model (gait 2392), and I then adjust the marker names so that they align with the plug-in gait marker set that was used and saved that marker set. I scaled the model using the static trial and saved marker set. One thing to note is that the plug in gait has a bunch of tracking markers that aren't placed with great precision, so they shouldn't be included in the model error. When I was adjusting the tracking weights, I remove all weight from these tracking markers (for example, the thigh marker). However, when I create the model, there is a large error due to the thigh tracking markers (which should not have any weight placed on them).

Why is that? How do I fix it?

Thank you!

[Ayman Habib]

Hi Aude,

Please try version 4.1 (still in Beta) as it may have fixes for the issue you reported (Markers being tracked even if not included in tracking tasks) and let us know what you find out. Keep in mind that there should be agreement between the names of markers in the model, data files and tasks (xml) files.

Best regards,
-Ayman

[Thomas Ruppert]

Hi Aude,

I am in a similar position to you were when you posted this! I am a new user struggling to get good results when using markers from my trc file. I have been trying to add and edit markers in the gait 2354 example from the tutorial, and have applied it to the model. When I run IK I get motion that resembles the original but is not really realistic for the body.

I know that you had a slightly different issue, but I am wondering what helped you and any reccomendations you might have for a new user that is using Opensim models with their own tracking data.

Best,
Tommy