Which residual is reaching < 9000N? In the screenshot there are some large FY values (>200 N). This might point out that there is an issue with the external forces you are applying to the model (either in magnitude or location or both). One way to check is to run Inverse Dynamics and see if reasonab...

There are some extra options with IK that you can use by editing an existing setup. You can create the setup file from the GUI by saving the settings, and then you can open up the setup file in a text editor (such as Notepad++). One helpful way to see all the tags is the XML Browser (in the GUI, Hel...

As long as you can get the external force/moment and the point at which the force is applied, this should work. For your canes, it seems like it should give you the force and point applied (with the markers). One question is whether the canes can generate a moment (something similar to the free mome...

There are a few options for how to do this. The Overview of OpenSim Workflows is a great place to start to see what might be best for your specific research question: https://opensimconfluence.atlassian.net ... +Workflows

The OpenCap webinar describes some ways to estimate kinetic quantities: https://www.youtube.com/watch?v=7Xk8-K7A3Zk In case it's helpful for future questions that are more specific to OpenCap, there is also a forum for OpenCap questions as well: https://simtk.org/plugins/phpBB/indexPhpbb.php?group_i...

The choices for optimal force values is important for RRA, and it's possible that picking larger or smaller values (for all actuators) can change the final simulation output (due to numerical and optimization differences). To get a sense of how to tweak these values, it could be helpful to go throug...

The LaiUhlrich2022 model is based on the LaiArnold (https://link.springer.com/article/10.10 ... 017-1920-7) and Rajagopal (https://nmbl.stanford.edu/wp-content/up ... 505900.pdf). These would be great places to start to learn about the construction of these models.

Thanks for the clarification, I definitely missed the part about different body frames. I'm not sure, but it does seem like you would still need to compare some common frame difference between the two if you need to get an orientation difference measure. Perhaps this could be done by creating axes f...

One way we've compared orientations between frames with a single number is using the "angle" measure of the axis-angle representation of the rotation between the two frames. This was done, for instance, in the OpenSense validation paper (see Eq. 1 in https://nmbl.stanford.edu/wp-content/uploads/Open...

Check out `Model::getCoordinatesInMultibodyTreeOrder` (documentation, code) which could be helpful your use case.

This is used, for instance, in Inverse Dynamics: https://github.com/opensim-org/opensim- ... s.cpp#L169