Link: http://cs-people.bu.edu/aaron/turret/turret.htm
The idea of this project was to create a fully-automated sentry gun, capable of picking out a human target and accurately tracking and shooting him or her in the heart. Really, the idea was to find a cool robotics project for the summer while I was working at an advertising agency, and I'd only ever seen sentry guns in movies (like Congo) and video games (Half-Life 1, Half-Life 2, Team Fortress Classic). I couldn't find any record of anyone building one, even the military, although it seems likely I just didn't look hard enough. It's a pretty simple technology. One of my friends did mention the Phalanx anti-missile gun, which is of similar design, but uses radar for tracking instead of an optical method. The Phalanx has been around since the early 80's. He was also quick to add that there are some pretty good reasons for not building an optical sentry gun, a big one being that it's generally a good idea to shoot down any missile headed in your direction, but that same philosophy may not be the best when applied to humans. If you're here just to see my little brother get shot with it, scroll to the bottom. I'm sorry this webpage sucks, it will get better with time.