[Willy Wampa] is showing off . What strikes us about the build is how well tuned his feedback loop seems to be. In the video after the break you will see that there is absolutely no visible oscillation used to keep its balance.
The parts used are quite easy to obtain. The acrylic mounting plates are his wife’s design and were custom cut through the Pololu service. They were also the source of the gear motors. He’s using a SparkFun IMU with an Arduino and a motor shield. He first posted about the build about a month ago, but the new revision switches to a Pololu motor driver shield which he says works much better, and adds control via a wireless Wii Nunchuck.

The PID loop which gives it that remarkably solid upright stance is from a librarywritten by [Brett Beauregard]. Once again the concept of open source lets us build great things by standing on the shoulders of others.

http://hackaday.com/2012/09/25/wii-n...lid-balancing/