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...

The _px, _py, _pz fields are the location of the center of pressure of the GRF - Unlike markers, which are by default in mm, force positions are expressed in meters, and are almost always expressed relative to the location of the global coordinate system (the axes you see in the GUI viewer). So when...

Hi Reese, You can use the PropertyHelper class (requires OpenSim 4.2+) to "trick" MATLAB into playing nice with the line of action plugin. You also have to add the directory the .dll file is in. Here is a GitHub gist showing how to do it: https://gist.github.com/johnjdavisiv/26b17b41afd7555e0c18f8cd...

I think Vincent is right, though you might not have to go to the trouble of creating virtual markers if you can extract the joint angles and if you can be sure they are expressed in the same coordinate system as your OpenSim model's joints. The IKTool is capable of tracking joint angles supplied as ...

You might want to check the <socket_parent_frame> and the <fixed> tags in the MarkerSet in your model - if these are set wrong that could cause the markers to get "left behind" during scaling. In the GUI it's easy to accidentally change the socket parent frame of a marker to the ground frame, but if...