Terrestrial snake robot model explodes/falls apart after some seconds of simulation

[Fredrikhb]

Hello,

I have a 3-joint 4-link snake robot which is composed of a custom shape to form its links using the Group node. The robot body is connected by HingeJoints, where the endPoint Solid has two children; another HingeJoint and a Group node( which consists of one shape and two pose nodes). I've attached the proto file as a .txt file.

My issue:
The model explodes/jumps off/yeets off the map after some seconds of simulation. It could be about 11 seconds, or 26 seconds. It works fine until this happens. I am using default motor settings. My code only applies a torque to the first motor. I have also tried reducing the model back to two Solids (composed of a group each) between the HingeJoint and motor as seen in the image below. Yet, even in the simplest model, they both rotate and wiggle about the anchor point forth and back as expected for a while, before they get blown off the map. What could cause this?

Things I have tried:
Changing density values.
Changing to mass.
Making sure there is a sufficient gap between the two arms in the anchor point.
Making sure they both start off the ground floor.
Resetting the motor velocity to 0 after each direction.

Is there some underlying issue with the physics engine when it comes to rotating and moving cylinders across the floor?

SnakeRobot.txt
.

[Fredrikhb]

Update: Applying a dampingConstant set to 1 seems to have solved the issue. I can understand that this pulls any mathematical "energy" back to zero, but I can't really see why it's necessary in this case.