Inverse dynamics differences - OpenSim 4.2 vs OpenSim 4.1
Posted: Wed Jun 16, 2021 7:27 am
Hi all,
I've noticed a big difference in inverse dynamics results between OpenSim 4.2 vs 4.0/4.1 using Ajay Seth et al.'s thoracoscapular model and was wondering why this may be happening. I know that the Scapulothoracic Joint is now built-in with OpenSim 4.2 as opposed to using a plug-in with previous versions (4.0/4.1), but was wondering if there was a change in dynamics with this joint that may have happened across versions. My understanding from going through the change and pull requests (2877 and 2932) is that the dynamics should not have changed (https://github.com/opensim-org/opensim- ... ANGELOG.md). I haven't noticed any big differences in IK or CMC results between the different OpenSim versions using this model (differences have been in the decimal places), so it's only the inverse dynamics results that seem to be affected.
I would attach the files here, but the attachments don't seem to go through due to a "board attachment quota", so I'll link the files I'm using here.
The model (ThoracoscapularShoulderModelSubject.osim) I'm using is the scaled model found in package here: https://simtk.org/frs/?group_id=1708. The motion file is abd01_IK.mot found under Results > IK found in the package downloaded from the above link. I filtered the coordinates at 3 Hz in the GUI and did not apply any external loads as it was a simple arm elevation motion.
To get the model to run in 4.1, I've been using the ScapulothoracicJointPlugin 4.1 found here: https://simtk.org/frs/?group_id=986
Any help or advice would be appreciated.
Thank you!
Dan
I've noticed a big difference in inverse dynamics results between OpenSim 4.2 vs 4.0/4.1 using Ajay Seth et al.'s thoracoscapular model and was wondering why this may be happening. I know that the Scapulothoracic Joint is now built-in with OpenSim 4.2 as opposed to using a plug-in with previous versions (4.0/4.1), but was wondering if there was a change in dynamics with this joint that may have happened across versions. My understanding from going through the change and pull requests (2877 and 2932) is that the dynamics should not have changed (https://github.com/opensim-org/opensim- ... ANGELOG.md). I haven't noticed any big differences in IK or CMC results between the different OpenSim versions using this model (differences have been in the decimal places), so it's only the inverse dynamics results that seem to be affected.
I would attach the files here, but the attachments don't seem to go through due to a "board attachment quota", so I'll link the files I'm using here.
The model (ThoracoscapularShoulderModelSubject.osim) I'm using is the scaled model found in package here: https://simtk.org/frs/?group_id=1708. The motion file is abd01_IK.mot found under Results > IK found in the package downloaded from the above link. I filtered the coordinates at 3 Hz in the GUI and did not apply any external loads as it was a simple arm elevation motion.
To get the model to run in 4.1, I've been using the ScapulothoracicJointPlugin 4.1 found here: https://simtk.org/frs/?group_id=986
Any help or advice would be appreciated.
Thank you!
Dan