Limit rotation on IK chain is global and not local

Support Animation and Rigging
1

Hi Blenderers !

I recently started my first animation and i am encountering an issue with the limit rotation on an IK bone. When i am moving the Main Body Bone ©, the IK limit rotation on Z axis (-24°/24° on image 4) stays on global axis instead of locals, that would allow it to turn with. The problem disappear when i remove this Z axis rotation limit.

I made a serie of pictures to help you understand the problem (the model has actually more objects in, but i deleted everything not related to the problem, to make it more clear).

The Main Bone (A) allow to move the whole structure. I use it because if i just select the mode, some pipes (that i deletd here because not involved in the problem) move away from model everytime i moved it.

So basically : how do i set the IK limit rotation in local and not global ? Thanks :slight_smile:

Sans titre 1
Sans titre 11920×1080 320 KB

Sans titre 2
Sans titre 21920×1080 297 KB

Sans titre 3
Sans titre 31920×1080 276 KB

Sans titre 4
Sans titre 4341×571 32.5 KB

2

I have a feeling that you’re probably misunderstanding what’s going on. IK angle limits are definitely local. However, local axes are created by a relationship to an actual parent bone. “Child-of” relationships do not create local axes.

I can’t conceive of any reason why you’d ever want to follow an IK constraint with a child-of, and the way that Blender handles IK kind of separately, kind of in a different order from other constraints, suggests that it might just bug out if you did that.

Try deleting the child-of and just parenting it to main body bone. Also, seriously consider other constraints for what you want to do, using an IK constraint to do this kind of transformation is a little weird (unreachable target, extremely limited angles) and I’d probably try to do it with locked tracks instead.

3

I’ve done this because i wanted the feet to stay on ground when moving the body, but indeed the Child Of was the problem. To make it keep going keeping feets on ground when moving the body, i’ve set the Child Of on the Guide at the end, works like a charm.

Thank you very much for the solution Bandages :slight_smile:

4

You should be looking at a floor constraint for what you want instead.

5

I did. But I wanted all the model to move when using the highest armature above the head. Without, the feet where always pointing at the ground