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I currently have a robotic arm rig with the shoulder only being able to rotate along 1 axis, and the bicep only being allowed to rotate along a different axis. I am controlling these bones with an IK controller, and It's working great, save for the fact that when I add a pole target to adjust the solution, all of my axis locks are ignored.

This issue has been driving me crazy, and I am wondering if there is a solution.

Here is the blend file : as you can see, the rig works exactly as intended, but when you set the pole target as the bone labeled "elbow" the axis locks are ignored.

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2 Answers 2

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As it turns out, this is impossible. The issue of ik constraints being ignored because of a pole target is a known problem. Hopefully support for this function will be added in the future. I might have to look into fixing it myself.

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Change the axis limit of the bicep and shoulder like this.

axis lock

Activate the axes display in the Armature panel.

You will see that the correct axis to unlock is the Z instead of the X. You can also change the manipulator to normal or local, to see this more clearly.

When the unlimited axis is the X the IK constraint can't bend in the desired way.

corrected_IK with pole

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  • $\begingroup$ This does not change the fact that adding a pole target for the IK chain invalidates the IK constraints. $\endgroup$
    – colorbomb
    Feb 13, 2017 at 4:09
  • $\begingroup$ You are right, I edited the post to clarify the steps to solve this. $\endgroup$
    – 3dvm
    Feb 13, 2017 at 6:03
  • $\begingroup$ You're correct, HOWEVER this does not apply if the ik chain has a pole target. $\endgroup$
    – colorbomb
    Feb 13, 2017 at 6:09
  • $\begingroup$ In this new image, you can see that the pole bone is set and working properly. $\endgroup$
    – 3dvm
    Feb 13, 2017 at 6:19
  • $\begingroup$ This does not solve the issue, because the shoulder bone is now rotating about 2 axes. The pole bone is overriding the rotation locks on the shoulder bone and the bicep bone. $\endgroup$
    – colorbomb
    Feb 13, 2017 at 6:55

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