A group of autonomous quadrocopters were developed by researchers at the Swiss Federal Institute of Technology (A.K.A. Skynet) to fly with such precision they can track and return a ball thrown at it with a fitted tennis racket head. Not only can one quadrocopter return a ball, but two of these guys can volley a ball back and forth (see video below)...
It's kinda cute to watch and also scary to think how fast technology and robotics are moving.
There are motion-capture cameras which track the quadrocopters from above. When the person throws the ball, it’s tracked by the camera, and a specially written program works out where the ball is going to go. The program then maneuvers the vehicle accordingly, angling it so it bounces toward the thrower.heeheee... watching them fly reminds me of the 80's movie *Batteries Not Included... :)