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

Match 2 – Stuyvesant vs. Union-Endi­cott

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.