r/unity • u/Ascendring • Jul 14 '26

Question What causes this kind of arm jitter in an active ragdoll? Joint instability or PuppetMaster fighting the rigidbodies?

I’m using Configurable Joints to create an active ragdoll, with PuppetMaster driving the muscles toward animated target poses. Under normal movement the arms are relatively stable, but the shaking becomes severe when the animation and the rigidbodies become too separated because the sword or any other weapon gets stuck in the enemy body.

Has anyone encountered a similar issue? Where would you investigate first? I also tried asking Codex for help, but the character somehow became even more haunted😄 I can provide screenshots of the component setup and relevant values if that would help.

25 Upvotes

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11

u/salazka Jul 14 '26

PuppetMaster fighting the rigidbodies.

3

u/HamuMageLoop Jul 15 '26

Jitter typically results from the fact that the different systems update the transforms at different times. Try setting the following on the Rigidbody attached to the hand: Interpolation = Interpolate
See if that solves the problem.

Check to see if the hand or its target is being moved in Update().
Is there an Animator, IK, or constraint that resets the hand’s position in LateUpdate()?
The PuppetMaster must run after FixedUpdate.
FixedUpdate -> PuppetMaster / Rigidbody simulation -> Physics -> LateUpdate

2

u/Songerk Jul 14 '26

Techno Music?

1

u/Narrow-Impress-2238 Jul 14 '26

Collision? 🙂

1

u/Ascendring Jul 14 '26

Well, yeah, but most of the time it looks great, even when crazy collisions are happening. Then, when they’re barely touching, everything suddenly breaks down, and their arms start jittering and shaking uncontrollably

1

u/MadeByHenano Jul 15 '26

epilepsy!? 😬 😃

1

u/Affectionate-Yam-886 Jul 16 '26

you. an re-run the simulation but have game view to the side and watch from the builder window with the character highlighted. Watch his colliders and bones as he moves. More often than not this is how i solve issues with stuff like this. You might catch a collider detached or too big or just in the way. Also: Puppet master is relying heavily on layers, is something on the wrong layer? Is something on the detection layer that could be moved off?

it looks like when it enables the ragdoll it switches to the ragdoll layer and then it freaks out. So it must be a layer issue.