If you look at a lot of the rotating panels out there, you will notice that they don't spin freely in a circle. Rather, they increment a certain amount in one direction, and a certain amount in another. That is to say, they rotate about an axis, but don't make multiple revolutions about the axis. With such a setup, you could easily run one cable or a bunch of wires back to your computer or encoder as need be.
Still, there are ways that a freely rotating panel could be done. You could make panels with wireless controllers built into them and rotate them all the live long day. It would be expensive, and would probably be a pain with the batteries and all..
Also, there are things known as rotary feedthroughs. I have a leslie speaker system that consists of speakers that spin about an axis.. this gives a great effect when playing organ music. Anyway, they get the wires in there somehow. Of course, running a few speaker wires is much easier than running a ton of control wires.
Later,
-88mph