RRA residuals

[Shivangi Giri]

Hello,
I am trying to reduce residuals by running RRA for a walking trial. I used the "Preview Experimental Data" to check the alignment of motion data with GRF and it looks good (Fig attached below). But as soon as I run RRA, my model goes down and then up. This I understand can be because of 1) either GRF is not strong enough or has not been applied properly and 2) because of the low value of RRA actuators at the pelvis.
The values of RRA actuators should be low to reduce residuals to a minimum. And after increasing the values of RRA actuators the model walks fine but the residuals produced are unacceptable. I tried the recommended mass adjustments so that the GRF matches the motion for that subject, but the issue persists.
Kindly help me to solve this as I have almost tried everything to make it work.

Thanks & Regards,
Shivangi

[jimmy d]

But as soon as I run RRA, my model goes down and then up.

You are running RRA when not all the forces are available. In the picture you posted, only one GRF is present, so the balance of forces and masses are inconsistent and the model will 'sink'. You should only perform RRA during periods when ALL the forces are known. During that gair, that would be single or double support when one or both feet are in contact with the forceplate.

[Shivangi Giri]

Thank you James for your reply. I apologize for seeing your post this late. Yes I understood what you said and also implemented the same.
I had another question. Why do the RRA moment residuals increase with mass adjustments? The force residuals are very low but average moment residuals are around 20 Nm whereas the moment peaks go as high as 100 Nm.
Please can you suggest something?

Thanks & Regards,
Shivangi