If you use a MuscleAnalysis, OpenSim will generate separate output files containing the normalized fiber lengths, etc. for you. If you wish to compute these quantities manually, you will need to set the state of the model from the data in the states file one row at a time and then call getNormalized...

The activation for each muscle can be found in the states file. You can use a MuscleAnalysis (https://simtk.org/api_docs/opensim/api_ ... ml#details) to generate additional files containing muscle-related quantities, including the other quantities you have listed.

The "pcsa_force" parameter scales the normalized force obtained from the force-length curve. The Ligament::computeForce() method can be found here: https://github.com/opensim-org/opensim-core/blob/02ac830cb81dd6dc2b01c2c32663b2237532ea8b/OpenSim/Simulation/Model/Ligament.cpp#L226 . On lines 242-243,...

It's difficult to diagnose the issue without more detail about what specifically you are plotting, what Tool you were using, etc. If the forces you wish to export are muscle forces and you are running the Static Optimization or CMC Tool, then you can add a MuscleAnalysis to the setup file. The muscl...

You may need to adjust the Geometry Search Path (see the "User Preferences" page in the documentation: https://simtk-confluence.stanford.edu:8 ... references).

It would be helpful to post the error message. Scanning the code, I see two potential issues: (1) You are calling the default constructor for the Body class, which I believe creates a body with mass set to NaN ( https://github.com/opensim-org/opensim-core/blob/main/OpenSim/Simulation/SimbodyEngine/B...

Based on the first line of the error message, there is a typo in the TRC file. The error message says that "OrigDataStartFrame" has been spelled "OrigDataStarFrame" (missing the second "t" in "Start"). More information about the TRC file format can be found on the "Marker (.trc) Files" page in the d...

No method 'setDataSource' with matching signature found for class 'org.opensim.modeling.ExternalForce'. The argument passed to the ExternalForce::setDataSource() method must be of type Storage (see the OpenSim 3.2 doxygen documentation here: https://simtk.org/api_docs/opensim/api_docs32/classOpenSi...

I was modifying an osim file manually using notepad This is not a recommended method for building models, particularly for OpenSim version 4.0 and later, since it is difficult to get all the details (syntax, component paths, etc.) correct. You might want to use the scripting interface ( https://sim...

Which version of OpenSim are you using? There was an issue in version 4.4 (possibly in earlier versions as well) where the ellipsoid drawn by EllipsoidJoint::generateDecorations() could not be hidden. This was reported as Issue #1440 in the GUI repo ( https://github.com/opensim-org/opensim-gui/issue...