Ribcage and volumetric structures in the new thoracic spine model

Main Forum
1

Dear AnyBody team! :smiley:

I'm currently working with the new thoracic spine model with volumetric elements to simulate subject-specific sagittal spinal alignment profiles.

The model works really well, however I have some 'constraint above tolerance' errors in some cases, i.e. when the subject's posture causes the rib cage 'sinking' into the volumetric structures.

I'd like to modify some of the drivers in the rib cage so that it does not sink into the abdomen. So my question is, which drivers should I change to "raise up" manually the ribcage?

So far, I gave it a try by changing the Pos value of this driver: Main.HumanModel.BodyModel.Trunk.Joints.RibCage.Manubriosternal.driver

AnyKinEqSimpleDriver driver = {
AnyKinMeasureOrg &ref=.ManubriosternalJointMeasure;
DriverPos ??= {2};
DriverVel ??= {0};
CType ??= {Hard};
Reaction.Type = {Off};
};

As a result (see the screenshot below), the ribcage has lifted, however, something strange happens to the first rib and the sternum seg. :face_with_monocle:

Could you please provide me some advice on how to solve this problem?

Thanks a lot!

Cheers,
Alice

Screenshot
Screenshot1920×2121 103 KB

2

Dear Alice,

To make it right, one thing could be that you remove the rib driver (RotationConstraint) on one of the ribs, maybe the first rib, and drive the rib angle manually. This can help keeping the sternum superiorly. And I know that the ribcage mechanism is complicated, and I think you should not change a lot in it. Just remove the rib driver and drive the rib angle.

best regards,
Hamed