I believe this is a problem with the implementation via Millard muscle type. After setting the states in the model I have been calling the following - Mod.realizePosition(state); Mod.realizeVelocity(state); Mod.equilibrateMuscles(state); When I do this, the I get force calculations, but the fibre ve...

We have been having some problems running inverse kinematics via the command line executable (via Matlab). IK works fine when ‘ReportMarkerLocations’ and ‘ReportErrors’ is set to false, however when set to true an error box saying 'ik.exe failed to work' pops up. We have the same error on both 64bit...

This is an interesting question. Generally, there is not a strong relationship between an anthropometric variable like height or leg length and muscle fibre lengths in more distal muscles that have long tendons and short fibres (e.g. gastroc, soleus, tib ant). There is very large variation which is ...

The ligament models are very sensitive to the resting length, and this needs to be scaled along with the origin and insertion points. If you take your model through the range of motion at the joint of interest and calculate the tension in the ligaments, then be careful to make sure this tension deve...

Thanks for this Sherm. This is exactly what I expected after looking into the visualiser code. The getMultibodyDynamics class is not exposed such that it can be accessed from Matlab or Python, however after looking at some previous posts I was able to achieve the same thing using - model.computeStat...

Yes, Luca. I have also found this to be the case. In which case there must be something called within the visualiser that adjusts the states properly. Does anyone know what this step is so I can call it directly from the API?

Sorry to keep reposting on my own post - but it seems that the path scaling is NOT working in the current version. At least in my implementation using the ScaleTool.

Some things I have learnt about the following questions through exploration and communication with Ayman Habib (thanks Ayman) What do the x-values for the force-length relationship represent? The equation used to calculate ligament force or tension is Tension = forceLengthCurve(path.getLength(s)/res...

I just wanted to add that I have been able to fix the problem with the 'getTension' method. Somewhere along the line the states that I were not adjusting were being reset to some default values which was causing the crash.

Hi everyone, I was wondering if someone may be able to help me out with regard to the Ligament model in the latest version of Opensim (3.2). I have read a few recent posts, but I would like the following to be clarified - How does the 'pcsa' value scale the ligament force-length relationship. Does i...