Several FreeJoints in one modell

[Carolin Renz]

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

[Ayman Habib]

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

[Carolin Renz]

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

[Ajay Seth]

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.