Polyend Perc is a drum striking system made from nicely engineered aluminium balls with strike mechanisms inside, you can feed MIDI in and play your physical drums via MIDI. It turns around the usual Trigger to MIDI you find in drum systems, and allows you to strike drums using MIDI instead.
Its a really interesting concept, up to now most robotic or mechanical drum systems, have been freakishly heath robinson, with all kinds of custom hardware to create the physical strike. The folks at Polyend have created a solid aluminium ball mechanism which houses the striking head, all controlled by MIDI via their custom controller.
The main kit comprises of 3 balls, and a controller unit. With an almost unlimited amount of units available, as each Perc ball, requires just one MIDI note. Its very fast, and very sensitive, though it won't whack a drum in quite the same way a large, hairy drummer can.
Here's another demo video which will give you more information