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Hi everyone,

I plotted the active and passive fiber force. I got a warning in the ‘messages’ window in the OpenSim GUI, which says that no suitable initial condition was found for delt2 and levator_scapula. they both have a high active fiber force and lev_scap has a high passive fiber force as well. Has anyone an idea how to resolve this or what the possible cause can be?

When did you get this error message? Was it when running one of the tools, or after simply loading the model in the GUI?

Try using a different pose for your model. Can you determine which pose of your model causes this error? Those forces look unrealistically high. Are you sure your muscle properties are reasonable?

It appeared after I plotted the active and passive fiber force. I dubbel checked my muscleparameters and they look fine. I also checked the movement during when the excessive forces appear. Levator scapula lengthens a lot, that could explain the high passive force. But I don't see anything special in case the active force is really high.

It looks like the muscle model is encountering numerical singularities. In Warnings.PNG, you have plotted fiber length vs. a joint angle. I don't know which joint angle you selected nor what the model looks like, but I'm guessing that the muscle has not been designed for these extreme poses (e.g., perhaps the muscle path is doing something strange). I would start by checking the publication accompanying this model and ensuring that you're using the model within the range for which it has been validated.