The design of the 6.270 tables was simple this year. One ball was placed in each corner of a rectangular table and a fifth ball was placed on an elevated platform in the center. If the middle ball was knocked off then two more balls would fall into the playing field from above at 20 and 40 seconds into the competition. The goal of the competition was to have more balls on your teams side of the table at the end of 60 seconds. The two sides were distinguished by their color, white or blue.
Because the design of the competition was so simple, it allowed for a wide variety of designs to be successful. We initially planned to go for the center ball and leave some kind of ramp so that we could deflect the two falling balls onto our side of the table. After thinking this idea over we realized that it had a weakness. We would only be able to get a maximum of three balls added to our side. We would have to hope that the opponent did not have a way to sweep the perimeter and collect the balls that were on our side, including the two additional balls that fell into the playing field.
Our final design was the chomper. The chomper was designed to carry balls. Instead of pushing them around the playing field it would eat them up and carry them inside. We designed it to hold four balls. If successful we would be able to hold enough balls on our side of the table to win the match. The difficult part of our design was making the chomping mechanism. The balls used in the competition were about the size of a softball and were made of smooth plastic. Our final chimping design had two large lego wheels mounted several inches out from the axis of rotation of the mounting arm. This allowed for the wheels to ride on top of the balls and essentially climb the ball as the ball was rolled into the front of our robot. After some tweaking, and the addition of three extra motors on the drive system we got the chomper working at 100%.
Now that our robot was able to carry four balls we planned to simply drive around the perimeter and collect the balls and then return to our side. Perhaps we were too optimistic. When we sat down to program the robot we ran into problems. We used differential drive which caused the robot to turn left as it went strait because the right motor was much stronger than the left motor. To compensate for this we added shaft encodes to each wheel and we were able to write a program that would adjust the power to the motors on the fly to allow the chomper to drive strait. After lots of bug fixing and program debugging we were able to write a program that would drive the chomper through the opponents side and collect the two balls without fail.