I have some IK chains on an armature for a human shaped model. I have an IK chains on both the hands and the lower arms but the IK chain on the hand is inactive (influence set to 0). I have some other constraints which act as IK/FK switches, and a Track to constraint to act as an elbow control. I set it up similar to option #2 on http://wiki.blender.org/index.php/Doc:Tutorials/Animation/Armatures/BSoD/Arm_Rigs but not quite the same (the bone called “arm” on that page is absent in my design and the track to constraint is on the upper arm).
What happens is that on the right arm, the upper arm ignores its IK rotation constraints. This doesn’t happen on the left harm even though it is set up the same way. In addition, the model does not follow the armature in 3D view, but it does when it is rendered. When I it G to change location on the elbow control bone, the upper arm follows its IK rotation constraints and the IK chain the way I want it to (even if I push G and don’t actually move it). However, once I change the frame, the upper arm continues to ignore its IK rotation constraints and stops following the IK chain. Even before I change the frame, it ignores the IK chain during rendering.
I thought I had this working the way I wanted to in the past but I can’t seem to get it to work anymore. Also, I find it very strange that the left arm works the way I want it to but the right arm does not.
ik_human_20100728.blend (425 KB)