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.