Benjamin, Thanks, that explains it perfectly and your fix worked! For some reason, our force plate data is in the analog section of the C3D file, and the previous OpenSim C3D reader somehow figured that out and gave us the the forces. Now it has the same behavior again which is good. I will still us...

Ayman, Thanks for the quick response. I downloaded walking2.c3d and no crashing happens with that one, no matter where I place it. So it's my file that is the problem. We export C3D files from Cortex (Motion Analysis Corp.). In case you need to test this, the (33 MB) file is here: https://drive.goog...

I was happy to see that OpenSim 4.2 now includes ezc3d, but Matlab crashes when I try to read a C3D file. It crashes on on line 68 in osimC3D.m: tables = c3dAdapter.read(path2c3d); The Matlab and Java crash reports are attached. This was with Matlab R2020a on Windows. I also did a clean install of M...

I am not familiar enough with Moco to answer that question. My answer was just to inform you about the approximation that is usually made in postural control models. In such models, the foot is "glued" to the ground. To prevent situations where the heel or toe would leave the ground, a bound on the ...

Yes, the diagram and equation are exactly right.

During standing, you can assume that y*Fx can be neglected and Fy is equal to body weight. Then you can convert the bounds on x (which depend on foot size) to bounds on Ma.

Ton

In models of postural control, this is usually done by placing upper and lower bounds on the ankle moment. That is equivalent to bounding the CoP.

Ton van den Bogert

In principle, there is no problem with muscle length calculations if you have additional degrees of freedom. My only concern would be that the inverse kinematic analysis is less robust, but I don't think it would make a big difference. If you want to know for sure, you can do it both ways: a 1-dof k...

Generating Lua code from the data will definitely work for me. And good to have the data separated from the code this way.

Thanks for the other suggestions and experiences. I will post again when I have my own experience or issues to share.

Ton

Hi Thomas, I have been playing with Scone (finally!) and am really impressed with the design and capabilities! One thing I am exploring is data tracking in a ScriptMeasure. I can't use MimicMeasure, mainly because I want to use heelstrike events in the simulation to synchronize the simulated motion ...

Nicos, Since the goal of sprinting is maximum speed or minimum time, data tracking should probably be avoided. I have optimized a periodic sprinting cycle by simply using "-V" as the cost function, where V is the speed. I added speed V and cycle duration T as unknowns in the optimization problem. No...