Limit rotation relative to non-parent bone for IK

I guess it is more of a noob question, but still I currently cannot figure it out. What I am trying to do is rig an arm consisting of just 3 bones (upper arm, lower arm, hand) and use IK on it. Requirements are:

  • moving the hand makes the upper and lower arm follow by IK
  • the direction of the elbow can be controlled
  • rotating the hand bone makes the lower arm follow, and when the lower reaches a rotation limit, the upper arm begins to move also

The closest I could come up with so far, was this:

  • add 2 extra bones for hand control and elbow control
  • add IK constraint to lower arm with target ‘hand control’ and pole target ‘elbow control’
  • add copy rotation constraint to hand bone with target ‘hand control’

To fulfill my third condition, I guess I would need IK constraints which go from child to parent (which seems not to be available). Can this be done? Or is there another way to get what I want? It seems to be such a simple matter…

hand-constraint.blend (506.3 KB)

Hey, Look here

Quite a lot of info there. Thanks. But do you have a specific vid in mind specifically relating to this problem? Have only found this about IK, but it’s not the right one: