What I need is to control bones of an armature by segments of a stretchy B-Bone in the same armature. To build what I had in mind, I would at least need the location and rotation of the segments.
If I had an idea how to fake the behaviour of a stretchy B-Bone (an equally subdivided curve with two handles), that would also be a solution.
What I tried so far:
Parenting the bones to the B-Bone. This doesn't respect the segments.
Using a mesh deformed by the B-Bone and Transformation constraints with vertex groups to control the bones. Doesn't work for the roll - which is important. Leads to cyclic dependencies because the mesh depends on the armature and the armature on the deformation of the mesh.
Using curves and Spline IK constaints to drive a bone chain. Doesn't distribute the curves tilt to the roll of the bones. Needs to be animated outside of the armature.
I made a small animation to show what I was trying to achieve, but I am basically out of ideas. The yellowish bones are the handles driving the B-Bone. The red bones should follow the segments (.gif unfortunately animated by hand).
Maybe there is a way to rebuild the behaviour of a B-Bone with some constraints or using a script that updates the bones while animating?