I wanted to rig and animate a worm using IK, so that if i move the tip of the tail i get the bend one would expect. Unfortunately using plain IK the tip will point towards the ground instead of staying parallel, easing into the slope of the arched spine.
This is what i end up with:
Ideally it should look more like a Gaussian function.
I thought that IK limits might help, but they are all relative to the previous bone and not global. To fix this i tried using rotation constraints, however, when the limit values approach usable angles the bend just "flips" along the Z axis so it's bending underground.