On the occasion of a week-long practical training in the university of Würzburg, I two-timed! Of course only with the used building-system, namely Fischertechnik.
The task was to construct a compact robot out of basic pieces, that is also stabile. Then it was equipped with electronics, which doesn't come from Fischertechnik, but has been a work by two students.
The robot was programmed with PBasic, a Basic language with some "specialities", which takes getting used to.
The final program should let the bot drive to given X-Y way points. It used a Gyroscop (measures angular rates) and a Hall sensor (measures magnetic fields, in this case the magnets on the wheels). After many programming and testing hours, Undestroyable reached an accuracy of about 10 cm aberrance after 6 points, which is quite noteworthy for this system and probably demonstrates the limits.
The program can be opened with every editor, more informations about it and the used microcontroller (Basic Stamp) can be found the homepage of the fabricator.