Inverse Dynamics

[Adriana Jorge]

Hello everyone,

I'm a masters student using OpenSim for the first time for my thesis. I've been trying to preform Inverse Dynamics using Rajagopal's model and data acquired using the Qualisys system. I have already successfully scaled the model to match my subject and also preformed Inverse Kinematics, which results I want to use for the Inverse Dynamics. However, I'm getting some weird results in terms of joint moments and I fear there might be something wrong with the ground reaction forces' file that I'm inputing. Other than that, I'm have no clue as to what can be the problem. Can anyone take a look at the GRF files and tell me if there's something wrong with them? And if not, does anyone have any suggestion as to what can be wrong? In attachment you can find an example of a GRF file and some joint moments I ploted from the results I obtained from that GRF file. I really hope someone can help.

Best regards,
Adriana

[Quinten Humphrey]

Did you associate your GRF data to your IK results to ensure it was applied to the correct body part?

[Adriana Jorge]

Not sure, how can I do that?

Best regards,

Adriana

[Quinten Humphrey]

When you run the tool for Inverse KInematics, a coordinate file will load in the navigator under your model. Right-click on that and click associate motion data. Your files will open, then look for your grf file and open that. Once loaded, the grf will display green arrows. Look to see where they are and the direction the arrows are pointing.