All Japan Micromouse Robot Competition is a robotics competition that takes place for 30 years with almost no-change in rules. The concept is to place autonomous robots inside a maze. The robots will explore the maze in order to map it and then they do performance runs from the entry to the center and the faster micro-robot wins. Last year the winner run the maze in 6.4 seconds and this year in the 30th contest the TETRA micro-mouse (pictured above) by Kato-san did a test run in only 4,7" although in the actual competition it disqualified.---



The TETRA micro-mouse is the cutting-edge of the competition, which attracts many innovative robots. It uses two pairs of closely stacked wheels, each one with its own electric motor. The CG is very low and most weight is placed over the front pair of wheels. As David Otten, a veteran of the competition explains in this video the TETRA is very agile in turns because its rear wheels have little vertical loading and their lateral grip is very low to provide resistance, so it turns like a two, side-by-side wheel robot. While accelerating, the weight transfers to the rear forcing all 4 wheels to the ground thus providing good stability. In the video David Otten say that they don't know how it can also brake as good, but the big front overhang might be the answer, it stops the robot from flipping over and the wheels can drag it while keeping it stable.

The TETRA was disqualified because the LED sensors it uses to detect the walls (by calculating the light reflection) got confused from the ambient lighting. Its creator says that this problem is addressed by comparing the data for its multiple sensors in order to cancel out the ambient lighting.



The images above show a maze plan and a screenshot from the competition. However those robots are extremely fast, especially when they figure out that they are in a mapped route, images don't do them justice, just watch these videos:

TETRA micro-mouse run
mouse-robot mapping the maze
(watch the diffirence in speed in the known parts, via BotJunkie )

Some links:
Kato-san website (in Japanese)
robotspodcast.com/forum
botjunkie.com/
robots-dreams.com

(images of TETRA from robots-dreams.com flickr )