Maya single chain behavior

Hi folks,

I’ve been toying for a long time with mobile pole vectors that orient an arm properly based on hand position and drive auto-clavicle motion. My last experiment had me writing a custom node in Maya that calculated arm quadrants based on azimuth / elevation calculations, which then drove some other nodes to move the pole vector into a set of positions.

Lately I’ve been playing more and more with the Single Chain solver in Maya. It’s great for limiting shoulder twist, but I’ve started using it to move pole vectors for RP chains. It makes me wonder: does anyone know the math behind the single chain solver? It’s not so simple as an aim constraint-- or is it? Is it just a matter of having an aim constraint where the “pole vector” of the single chain solver is effectively parent constrained to the handle to get those rotations happening?

Thanks in advance,
~ k