Apperently something went wrong with attaching the files, I reattached them now. - I eddited a .mot file to define the motion. I also added these files in attachement. - And Indeed I am looking at the center of mass columns of the BodyKinematics, both at the linear and rotational. Thanks again for t...

To give some more background, the jaw is attached to the skull with 2 tempormandibular joints (TMJ's). So I split the jaw in 2 parts, to avoid problems with the fact that in opensim each body can only have one parent body. In the attachement you find 3 models and their kinematics. only_left has only...

Thank you for your reply. Yes indeed I would not expect gravity to show up in the acceleration. I am applying a constant rotation, so no falling. And I included the topology view in the attachment. Here I meant with simplification mainly geometry (I am also looking at dynamics and the differences wh...

Thanks for the reply. I set the gravity to 0 and then the -9.81 offset in the y-axis disappears, but I still have accelerations that I can't explain...

Hi all I am currently working on a jaw model. I added a screenshot and the topology view in the first slide of the attachement. I used a simplified model to be able to compare te results with manual calculations. At the moment I am looking at the body kinematics from a constant circular rotation aro...

Hi, Do you perform Forward Dynamics or Inverse? OpenSim ignores constraints during Inverse Dynamics. Also make sure that the initial state is consistent with the constraints. Best Hi, I am currently working on a jaw model. I defined it as the skull with two children, namely the left and right part ...

Also, while I was trying to make the new model, I accidentally ended up with a model where the parts of the jaw could move separately. But I checked the results of the inverse dynamics anyway and they seemed quite similar to the ones of the model with the weld constraint. So then I decided to make 2...

Okay thank you again for your reply. At the moment I am trying to make the model with spherical joints for the TMJ and a slider joint between the two parts of the mandible. The problem is that I can't define a joint between 2 bodies which are already child of the same parent body. So I guess I have ...

Okay I will give that a try, but than the problem is that a real TMJ does have 6 DOF. Of course the translations are small, but they can not be neglected.

Thank you for your fast reply. I did gave both TMJs 6DOF as this is indeed closer to the anatomy and indeed a model with 1DOF gave problems. So if I am right then I get for the mobility: For the model with one joint: 2 bodies and 1 joint with 6DOF => M = 6*(2-1-1) + 6 = 6 For the model with two join...