Bluebot-L (about to retire)
The design of the base is terribly flawed, but everything else works well :)
The base is much too long, and there are two sets of batteries at each end. This has two bad consequences: the robot has a high moment of intertia, and a small change in direction moves the light sensors too much.
As a result the robot over-corrects and hunts. I'm going to wheel it out for one last run so that I can create a video record, and then it will be retired to be reborn once I have made a new, more sensible base.