I have a simple robot claw rig - it’s just a couple of bones with an IK solver at the end, and two ‘pincers’, which rotate in opposite directions.
The pincers are constrained so they can only rotate on their local Z axis, but the rest of the bones aren’t. I’d like to be able to move the actual arm in three dimensions.
This rig doesn’t work: when I move the IK solver somewhere that’s not directly in line with the X-axis, it all rotates and I have no control over the rotation.
Ideally, I’d like to control the whole thing by having one ‘hand’ bone, whose position and rotation I could control directly, which would then set the position and location of the claw-bit.
Is this possible, and if so, how do I go about it?
Click on the console window and see if it has any messages about cycles - if you are losing control of the rig there is probably a cyclic dependency (A depends on B, but B depends on A).
I have just been playing around to try and get the sort of rig you are doing and this is what I came up with:
It is as follows:
two segments of arm on right
these have a small IK target and two claw bones attached to the end
IK -> no target, chain length doesn’t matter for mine but depends how many links in your armature and if meant to influence higher bones or not
two pairs of floating bones - a scaler and an IK target (the little one)
these scaling bones are parented to the last bone in the arm segment (not the IK or will result in cyclic dependency)
The scaling bones copy the scale of the arm IK, the claws have the little IK targets as… IK targets.
End result - move IK bone around and arm follows to point towards it; scale IK bone and the scaler bones get bigger and smaller, moving the IK targets closer together or further apart and allowing the claws to pinch and release.
For show you can limit the scale of the IK bone to prevent overdeformation and hide all the other bones so your armature is controlled by a single bone with location and scale only.
I hope that makes sense - have uploaded file to mediafire at:
EDIT: Is there anyway to control the angle of the pincer relative to the arm? Ie, no matter where the arm is bent, the two yellow bones are parallel to the Z axis (or, even better, parallel to something I can directly control)?
