I’ve made inverse kinetics for each of the legs, and I’ve been using the base’s bone to see how it works. I found it the whole model freaks out once the model reaches a certain point.
I’ve made a gif on the problem:
http://imgur.com/Xs8IN4a
With Ik you want the bone to move from the foot as that is where the weight will be distributed. The bone you have the ik on is your leg bone. Unless your going for a different affect.
Like SimplyD3D said, the IK constraint needs to be on the last bone in the chain. IIRC, the controller bone can’t be a child of the chain. Also, make sure the chain length is set to the # of bones you want the IK to affect.
Randy