Dear Isaac Team,
Isaac Sim 4.5.0, Ubuntu 22.04, RTX 3090 driver 535.113.
I build a long “soft rod” by chaining 17 capsules with RevoluteJoints.
Each joint frame:
- axis alternates Z / Y / Z …
- lowerLimit = -1 deg, upperLimit = +1 deg
- no extra stiffness / damping set (left at default 0)
Gravity is set to (0, 0, -9).
When the simulation starts, the rod bends far beyond the ±1 deg limit, even though no drives are active.
Is the USDA setup wrong, or is PhysX currently unable to strictly enforce small swing limits on a long, light-weight articulated chain under large gravity?
Repro files attached:
1.txt (29.0 KB)
Thanks in advance!
Hi @zhaowentao, thanks for posting your question. I believe that your rod has a lot of segments. If that is the case, then the joint limits are set for one link relative to the parent link. So if you set all of them to 1 degree, then they will add up as you progress down the chain. E.g. if you have two joints, then the first joint can move up link 1 to 1 degree down relative to link 0, the second joint can move the link 2 by 1 degree down relative to link 1, and 2 degrees down relative to link 2 if link 1 is at the lower limit. Does that make sense?
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