how to setup an ik chain with multiple bones using control rig

UnrealEditor_413Uby5sb6

I’m trying to create an elbow hinge ik setup across multiple joints using the two bone ik function. but since all the bones are not aligned in a straight line, the rig gets misaligned . is there a workaround for this

… TWO bone.
Why would it work on 3?
:stuck_out_tongue:

I think you just got the setup wrong on the skeleton possibly.
The position changing the way it does when you connect the IK would indicate that the rest of the skeletal mesh is not parented onto that specific bone.

BTW, IMHO this is a mechanical thing. it should not be using a skeletal mesh in the first place.
Yea it’s easier to set up, maybe, but if you went and made it with separate mesh parts correctly parented and socketed you would get 100% accurate results always.
That’s because the skeletal mesh can compress the mesh between joints, and the mesh itself will never be able to.

Setting this up with separate parts and different BP Joints (1.5 - PhysicsConstraints | Unreal Engine 4.27 Documentation) is probably the way to go about it.

1 Like

i,ve tried a few different ways to rig this inside of unreal. but without much luck. the problem is definitely not with the skeleton cause i,ve exported an fbx animation and it works without a hitch.
i was hoping to recreate the same setup using control rig. maybe use it with sequencer. maybe :grimacing:

think i need to find for a better way to get it working inside of unreal.
UnrealEditor_aEWi6yJb6T

maya_sXPrYaVc6D

The fact an animation works has nothing to do with the skeleton being right or wrong.
A DCC sets and exports ALL bone positions, not just 2 as the IK control rig nodes would.
As such, it’s not any indicator of the skeletal structure integrity.

Putting that aside.
IK works from Final point - solving rotations back to the base.

What it will never do, is keep the motor on top rotating along with the bone it isn’t actually attached to - so your skeleton is visually wrong as well. (though a quick parenting change of the bone may solve it).

All that said. Doesn’t control rig support FABRIK and other solvers by now?
Use one of the more advanced solvers, and you could potentially get it to work better.

For my money, changing from skeletal 2 static is still a no-brainer… The difference for animating it is that you have to use Take Recorder.

1 Like