simtk.org

Hi Moco Team,

I attempted to run Moco on Ajay Seth's thoracoscapular model to predict scapular + humeral kinematics for an arm elevation motion but didn't realize that ScapulothoraicJoints aren't supported yet in Moco and ran into error issue (generalized speeds don't match the derivative of the generalized coordinates: qdot != u). I should've probably checked the release notes before running the simulation as this warning was there in the release update. Anyways, I wanted to ask if there is a timeline on when the ScapulothoracicJoint along with other problem joints (BallJoint, FreeJoint, EllipsoidJoint) will be supported in Moco? The error message also stated to consider replacing with a "CustomJoint" -- do you have any advice on how to go about doing that for the ScapulothoracicJoint?

Thank you!

Dan Mulla

Hi Dan,

Yes, we current do not support the Scapulothoracic joint and the other joints listed. No current timeline, but we'd like to add it to Moco soon.

The Scapulothoracic joint is very specific, I think it would be difficult to replace it with a CustomJoint.

Aaron Fox recently published a paper using the Wu shoulder model in Moco: https://www.biorxiv.org/content/10.1101 ... 880v2.full. This model works, although I'm not sure you can predict scapular motions with that model.

-Nick

Hi Nick,

Thanks for the reply and update. Unfortunately, the Wu model doesn't allow for free scapular motion. Looking forward to when the Scapulothoracic joint will be supported by Moco in a future update -- happy to test things out if needed.

Take care.

Dan