simtk.org

Hi all,

I''ve been working with OpenSim 4.0 and am have experienced an issue with the visualizer and certain muscle paths. When I run forward dynamics, the simulation completes successfully, but I can't view the results in the GUI. When I hit the play button to animate the model nothing happens, but there is dof motion when plotted.

If I remove a particular muscles (EDCs) from the forceset, the simulation completes and the results can be viewed. Furthermore, if I remove the pathwraps for these muscles the simulation also completes and I can see the results as well. It's clear that there is some issue with the path wrap for these muscles, but I'm not sure if it's just a visualization issue or there is a problem with the way the paths wrap on the wrap surfaces. When I plot the moment arms, I don't see any discontinuities, so I'm thinking it may just be a visualization problem. The visualizer also freezes when I drag the coordinate sliders, so it's been hard to see exactly how the wrap surfaces are applied.

I was wondering if anyone else has experienced a similar problem and if you have any recommendations for this. I'm attaching a simplified version of my model that can recreate the issue.

Thanks!
Daniel

Hi Daniel,

Thanks for reporting, I'll take a look.

Generally speaking, path visualization issues are unrelated to simulation results since the visualizer uses its own mechanism to optimize path display/update. It's very likely that there's an ubrupt change in path wrapping or the combination of various PathPoints that are active/inactive that are specific to this model/configuration.

I'll let you know what I find out.

-Ayman

Daniel-

You have to try and simplify this model. This is far too complex to be useful. It has ~63 wrap objects, mostly ellipsoids, where most muscles wrap around 4-5 wrap objects. This is literally nightmare inducing.

You, and others, won't be able to troubleshoot your model because every time you have the slightest issue, it could be one of (literally) a thousand problems.

I strongly suggest that you simplify this model, otherwise you will be having ongoing, unsupportable, issues moving forward.

-J