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Hello all, I have a question regarding inverse kinematics that I never really thought about until now. I'll share some details before asking just so you understand what I mean. So, I ran the inverse kinematics tool and got results. Then, using those results I was able to perform inverse dynamics.
Now, if I were to restart OpenSim and load the IK motion to the same model, I get an error "java.lang.IndexOutOfBoundsException: Index: 154, Size: 147" which I'm assuming is because the location of the model isn't the same as the location for the IK data?

I have discovered that the pose my model creates after running the IK can be set as the default. It changes the posture but I am able to load the IK motion data if I were to restart OpenSim.

So for my question, is it okay if I use the pose my model creates after IK or do I need to change the model's location another way? Will the first way cause any problems with RRA/SO/FD?

Hi Quinten,

The issue here is likely a visualization issue that has to do with visualizing path wrapping. IK by itself doesn't use muscles altogether. This is very specific to your model and the motion as users solve IK problems routinely without an issue for a variety of models. Please open a bug report and attach your model and motion so we take a look into this issue, likely caused by drastic change in wrapping configuration from one frame to the next. As a visualization issue, it should have no effect whatsoever on downstream analyses/tools. Typically these tools either require initial states or pose the model in default pose before solving.

Hope this helps,
-Ayman

Yes it does. Thank you Ayman and I will open a bug report.