Usually that error is caused by having the file you're trying to write to open in, or accessed by, another program. For example, if you have that .osim file open in a text editor because you're editing it, that will cause this error. Ditto for .sto files in Excel. More rarely, sometimes there are "o...

I can't speak to the automatic tool, but from the data in your folder it looks like the source of your problems is that the foot is not "tall" enough. From your scale setup file, you are not scaling the height (Y axis) of the calcaneus or talus or toes at all. This is going to lead to a poor fit sin...

I have a github repo that shows how to use muscle volume to scale max isometric force. My use-case was using the Handsfield regression equations that predict muscle volume from height and weight but you should be able to pretty easily adapt the code to your data! https://github.com/johnjdavisiv/scal...

The hip joint centers are just wherever the hip joint centers were in the skeleton that was digitized to create the generic model. So, for that particular skeleton, they are "perfectly accurate." In fact in MRI studies, the gold standard for hip joint center is literally just the center of the head ...

Hi Nick, thanks for the great new feature! One quick thought/question - do you think the FunctionBasedPath class could also be used to "port in" muscle lengths and moment arms that are calculated elsewhere? From the docs it sounds like it should work as long as you can create a Function object for a...

Two things come to mind: First, I've found that I shouldn't always trust the visualizer--I've seen those 'double muscle' bugs sometimes and they don't always reflect actual errors in the wrapping. Checking the moment arm in the plot tool will sometimes show the wrapping is working just fine (though ...

In the images, I noticed that the troublesome muscle appears to pass through a torus wrapping surface too. I've found that those torus wrapping surfaces can cause exactly this kind of "jumping" or "falling off" behavior on other wrapping surfaces. Try replacing the torus with a via point (located at...

I'm pretty sure the "errorVariance" is a just a regularization parameter: a smoothing penalty such that, the greater it is, the smoother (less "wiggly") the spline fit is. The "GCV" stands for generalized cross-validation, which based on my read of the docs is how the method chooses the errorVarianc...

You might consider using the Arnold 2010 model - it uses muscle parameters from Ward 2008 which used 21 cadavers that were ~82 years. The Arnold model uses a specific tension of 61 N/cm^2 (higher than what's typically estimated from direct measurements of muscles) to scale PCSA to max isometric forc...

I'd also like to throw my hat in the ring to request opensim-moco availability on Conda for Linux (and MacOS). I'm switching over to Linux/Mac + Python (from Windows + MATLAB) for my research and being able to start working with Moco would be great. The regular opensim distro on Conda works like a c...