La Cucaracha – Sumo Bots 2007

Two years ago, we at Stuyvesant Techtonics built a robot that was nicknamed La Cucaracha (“the Cockroach” in Spanish). It uses the same gearmotors (550-sized motors with a 51:1 aluminum-cased planetary gearhead flush with the motor can) as Harpy, as well as Victor 883 motor controllers and 3-cell lithium-polymer batteries. The motors were mated to Lynxmotion foam rubber sumo wheels and tires.

The Victor motor controllers and Li-po batteries (which were not as common in SO at the time) allowed La Cucaracha to take full advantage of the drivetrain in the robot. However, its rear-drive two-wheel design was not ideal for maneuverability. Moreover, it caused weight distribution problems—much of its weight rested on the forward scoop, and the whole robot pivoted about the wheels. Thus, despite having a straight, sharp, hand-filed scoop, it “rocked” atop the surface of the ring and its scoop would ride on other robots’ scoops easily.

Finally, the addition of a Basic Stamp 2 and breadboard to the electronics proved disastrous. Its purpose was to mix servo signals— the radio we used had two servo channels, one for the forward/back movement of one joystick and another for the left/right movement of another joystick (another radio was borrowed by Ben Lee of Techtonics from Stuyvesant 694, but was fried. This more or less marked the beginning of the schism between Techtonics and Stuypulse).

However, the BS2 carrier board, a breadboard, and the EPVC board used to mount and protect the electronics were all mounted above the upper shell of the robot, on standoffs. This shifted the center of gravity higher on the robot, but the acceleration of the robot due to its high-power drivetrain was such that this would cause La Cucaracha to “pop a wheelie” when driving forward, which can be seen in the videos below. Even worse, the breadboard construction and poor isolation (from motor controllers) of the mixing circuit was unreliable; it failed during a bout against Stuyvesant’s much-ballyhooed rival, Townsend Harris. The BS2 required a hard reset in order for the bot to be functional once more.

New York State Tournament 2007
Match 1 – Stuyvesant vs. Unknown

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Match 2 – Stuyvesant vs. Union-Endicott

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All of these problems served as great lessons for subsequent years in the Sumo Bots event. Nazi Hooverbot, the result of the next year’s work, compensated too much for these problems: it was relatively underpowered (as La Cucaracha was seen as too powerful), it had four wheels, and scoops on every side of the bot. However, for 2009 I took lessons learned from both years, combined with machining and design experience, and produced a juggernaut of fast, low-hitting pushing power: Harpy.


About Me

Personal logo. Copyright © 2010 Xo Wang. Hi, I troll engineer firmware, software, silkenware, and extra firmware at Google. I’m your friend from Stuy and Georgia Tech. Or you might know me from Apple, Invention Studio, Solid Angle, and Science Olympiad. You can find me in San Francisco on a motorcycle, exploding circuit boards.