David P. Anderson's work on robot localization and behavior with JBot is classic, and well worth studying: jBot: The Journey Robot - David P. Anderson
In particular, check out this video where the robot goes out (in out-of-doors) for 100 feet, and returns to the same spot. http://www.geology.smu.edu/~dpa-www/robo/jbot/jbot_100x.mpg