Tankbot I
This little guy was my first attempt at a robotics platform. It has had a variety of controllers and sensors on it throughout the years. The latest incarnation is a mega16 with some older motor driver and encoder modules.
This platform started out as a kit like this one.
Pictures
The bot now has a cliff sensor and will run around a tabletop without driving off the edge (hopefully anyway). I used a GP2D12 IR sensor which seems to work reasonably well. Now I need to add other sensors to keep from bumping into things and an RF link for commands/feedback.