Using the Range constraint for keyframe animation

This method lets you keyframe the movement of each effector without having to transform and key the root of the skeleton.

1. Set up a biped skeleton with Chain IK constraints for each leg.
2. Use each foot effector as the root in a Range constraint, the effectors being the source and the root being the constrained object.

   When you translate the effectors for each foot, the hips move as well.