Sean Hodgins @ idlehandsproject.com writes:
After I built the tiny balancing robot using an IR sensor for stabilization, there was a comment on the youtube video about how it would be a good thing for kids to build and learn about PID controls. I thought that was a great idea, the only problem was that that tiny robot was the simplest of balancing robots. It was just an on off switch for telling the motor which way to move. There was no actual PID implementation in that system. So that got me thinking about how it would have been really cool if in one of my classes where I was learning about control theory I had a robot that actually let you see the changes in a PID system in real time. I decided to take it upon myself to create such a robot.
PIDDYBOT – A Self Balancing Teaching Tool – [Link]