Micromouse - IEEE79-1
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Back to - Micromouse - The early years 1978-9 21 March 2014

IEEE spectrum 1979
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SPECIAL REPORT
Microprocessors
The amazing micromice:
see how they won

Probing the innards of the smartest and fastest entries
in the Amazing Micro-Mouse Maze Contest

    The stage was set. A crowd of spectators, mainly engineers, were there. So were reporters from the Wall Street Journal, the New York Times, other publications, and television. All waited in expectancy as Spectrum's Mystery Mouse Maze was unveiled. Then the color television cameras of CBS and NBC began to roll; the moment would be recreated that evening for viewers of the Walter Cronkite and John Chancellor-David Brinkley news shows. The final races of the Amazing Micro-Mouse Maze Contest were beginning at the National Computer Conference in New York, and what was perhaps most amazing was the wide public interest that the competition had evoked almost since its inception.
    Publicity was not the chief goal when the micromouse contest was conceived. Nor did Spectrum's editors suspect that more than 6000 entries would be received. A modest announcement of the contest was made in the May 1977 issue of Spectrum by Editor Don Christiansen, who first suggested the contest. Later Computer magazine became a cosponsor.
    A secret maze was constructed, and the show went on the road, with time trials at the National Computer Conference in Anaheim, Calif., Personal Computing '78 in Philadelphia, WESCON in Los Angeles, and ELECTRO '79 in New York City. The challenge was to employ microprocessor technology to design and construct a self-contained "thinking mouse" that could solve a maze and, in subsequent trials, avoid its earliei mistakes. A loophole in the rules, however, let strictly mechanical, "nonintelligent" mice enter, too.
    At the finals in New York's Sheraton Centre, three engineers - two from Battelle Northwest and one from WED Enterprises - teamed up to score a sweep as two of their entries took prizes for fastest and smartest mouse, respectively. Four other micromice solved Spectrum's maze, and two won prizes. Of the 15 micromice entered, only six managed to solve the maze at least once. Cattywampus, a smart micromouse, did not solve the maze but won a prize for "the most ingenious design."

Mice that could learn
    Learning by exploring was, in essence, the algorithm used by Moonlight Express (Fig. 1) as it negotiated the maze in record learning time. Designed and built by Art Boland and Ron Dilbeck of Battelle Northwest Laboratories, Richland, Wash., and Phil Stover of WED Enterprises, Glendale, Calif., it was an improved version of the Moonlight Special, a smart micromouse that had demonstrated its learning prowess at previous time trials of the contest as well as at the finals.



Roger Allan   Associate Editor
    The major difference between the Express and the Special was in their foward speeds: the Express had stepping motors with four times the torque used on the Special. Top motor speeds of 52.07 cm/s for the Express vs 20.32 cm/s for the Special were made possible. In addition the motor-drive circuitry for the Express was strengthened to handle the increased load of the new motors, and the Special's gear train was entirely eliminated.
    Some of the hardware used in the Special - for example, interrupt logic - was eliminated by the use of IC devices that were exclusively from the Z-80A family of components (the Express was based on the Z-80A microprocessor, as was the Special). This represented only a slight modification of the earlier electronic circuitry in the Special (Fig. 2).
    A distinguishing feature of the Special was that it looked like a real mouse. Everything else - the optical sensor arrangement, battery supply, and the high-level software - were the same in the Express as in the Special.
    The Moonlight Express and Special were equally intelligent. Both went through the maze on their first runs, exploring paths and mapping nodes (or three-way crossings) into their memories. Both solved the maze on each of their second and third tries, traveling the shortest possible maze routes, from entrance to exit.

Doing It with logic
    Not all micromice at the finals contained microprocessors. Dudley and Mushka, two Canadian entries, managed to solve the maze with simple IC logic (Fig. 3). Both had been built from the same basic design, and each solved the maze on its last run in 252 and 94.74, s respectively. Dudley was entered by David Schaefer of NCR, Waterloo, Ontario, and Roger Sanderson of the University of Waterloo. Mushka, which won the runner-up smart prize, was entered by Bob Norton of Hamilton, Ontario, and John Ditner of the University of Waterloo.
    The original designs for Dudley and Mushka (Fig. 4) called for a 1602 microprocessor, a Model 2758 EPROM with 1k x 8b of memory, a peripheral interface adapter IC, and three infrared sensors. The sensors were to detect the presence of walls around the mouse and to allow it to negotiate the maze without touching the walls. A software algorithm that would have provided the mouse with learning capability on successive trials was to be included. All of this was scrapped at the last minute, however, in favor of a simpler logic circuit due to insufficient time before the finals to do this.
    Each mouse used two 3-V hobby dc motors to drive left and right wheels. Front and right switches activated a pair of one-shot multivibrators and three OR gates. Normally the mouse's left wheel was driven forward to the right When the

62 0018-9235/79/ 0900-0062500.75 1979 IEEE IEEE spectrum 1979

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