simtk.org

Hey there,

I have a general question about FreeJoints:
I have a modell containing one block which is connected to the ground with a FreeJoint.
Additionally I wanted to add five cylinders, being again connected to the block with FreeJoints.
And this was (for whatever reason) not possible.... I tried to define the cylinders to the ground (again with FreeJoints) but that didn't work either. In both cases, I was not able to open the modell, because OpenSim broke down immediately.
In order to check my code, I created a new model and added the cylinders (with FreeJoints and the ground being the ParentBody). There was no problem about it.

My conclusion is now, that I can only define one FreeJoint per Modell. Is that right? Or if not, where could be the problem?

Thanks for your help =)
Carolin

Hi Carolin,

There's absolutely no restriction on the number of FreeJoints in a model. Please post your .osim file and I'm sure we can help you figure out what's wrong with it (Likely missing body specification/typo) or misformatted xml if you're editing the file manually.

Best regards,
-Ayman

Hi Ayman,
thanks for your fast reply. I've attached the osim-file (Kniekinemator_Knie_2_Weld.xml, because I could not upload it as *.osim). I wanted to connect the cylinders (S_rf, S_vm, S_vl, S_rf, S_sm) with a FreeJoint to the body "Block_oben". The example I've uploaded connect them with a WeldJoint. Maybe you can give me an example of how to do it right.
Thank You again.
Carolin

OpenSim requires adequate number of Coordinates be specified with the corresponding Joint type. In your first use of the FreeJoint with the ground had 6 Coordinates specified and the others have none.
I suspect that is the problem.