different outputs of the inverse dynamics tool between opensim4.1 and 3.3

[Wang Xingyue]

hi, I converted an opensim3.3 head and neck model to the latest version(opensim4.1). But when I used the same motion file in the inverse dynamics tool, I found something different in the storage file. In opensim3.3, these titles are pitch2_moment, roll2_moment and yaw2_moment. However, in opensim4.1, those are pitch2_force, roll2_force and yaw2_force.

I think it should be torques not force. But I don't know which part is wrong. Hope someone can help me!!

[Ayman Habib]

Hello,

One of the issues that should be observed carefully when upgrading models from version 3.3 to 4.0 is the fact that coordinates were allowed to have user specified types that were inconsistent with the joint definitions. This has been mentioned in the release/upgrade-notes here
https://simtk-confluence.stanford.edu/p ... d=28777222

Apparently some coordinates were declared rotational in version 3.3 (causing results to be reported as moments) while in fact they are defined as coupled (per the underlying joints). This has been fixed in 4.0 and later.

Please check the upgrade notes linked above to see if you have result files that need upgrading or regeneration in the latest version.

Hope this helps,
-Ayman