I don’t know if this is new but I’m calling it double strung quaternions (DSQ). Its a method to reinforce a rotation relative to a transform space. In lamens terms it trys to make rotations true to our way of seeing them in a control. I’ve been looking into ik spine systems and hopefully this maybe a way towards helping out with rotation issues. Here’s a demo using z as its direction.
(click on the above image to view it the demonstration)
Bugs im noticing are that it uses linear distances to work our the quernions, quatDrivers as I call them (they can infact drive any value with distances) – i get some slight wobblying, but i think this can be cured using a valuespace normalisation method like so:

a = 10, b = 20

summation = 30

norm a = .33 norm b = .66

multiplication by the norm gives a = 3.33r and b = 13.66r
This is a derived final value which might yeild better results. The whole system is enclosable and useable across a variety of articulation problems.