Servo - June 2008

team for the FIRST Tech Challenge. I immeditaly registered, and my FIRST 2007-08 season began!

When my Vex kit finally came in the mail, it was building time, right away, without hesitation. I already had many designs in my head for this year’s game entitled Quad Quandary, in which alliances of two robots each must score points with rings and hexagonal goals around the field. My first design was a three wheeled ‘scooter’ robot which could grab rings and easily score them on the high goal. Well, with limited parts, this proved difficult. Eventually, wanting to follow the K.I.S.S. principle (Keep It Simple, Stupid), I tried a different design.

Another five designs, all with a powerful drivetrain, but they each were ruined by my huge, complex arms. With only so many parts, it was hard to build an arm, let alone be able to pick up plastic rings with just the small grip of metal attached to the servo motors. So, after much thought and now designing with the consideration of the amount of parts I have, I went to Plan B. No arm. How can I score points with no arm!? Well luckily, the Game Design Committee gave teams like mine the luxury of a side goal. This side goal is flat on the ground with one point given per ring score.

There was also the option to push the hexagonal goals into your sectors for another seven points, which luckily scored a lot in the actual game. Another advantage to my new design would be torque! I planned to have enough torque to be able to push whatever robot or obstacle stood in my path. Also, I wanted to be able to push those goals (which turned out to be simple!). This last strategy took a few design iterations. The first was another attempt at a high torque ‘scooter’ ‘bot that had omni-directional capability. My original attempt at this failed and so did my second one which actually came very close to success, but when it came to programming autonomous mode (key part to the

FIGURE 1

game!), it didn’t make the cut.

My last gloriful design was relatively simple and yet extremely powerful. It was a simple 6WD robot with a plow and sensors scattered over it. The 6WD gave it so much torque it could even push the two-time champion robot built by Simbotics (see Figure 1). The plow was really effective at getting rings and hexagon goals into their locations quickly and not stopping because some robot tried to get me!

Before I talk about the competition and what happened on that amazing day, I want to go more in-depth about actually building the robot with the Vex Robotics platform ( www.vexlabs.com). Building with Vex allows you to be creative, and build robust and powerful ‘bots without using all those expensive shop tools like band saws and power sanders. The only tools I used with building Vex were two Allen keys (or hex keys, hex wrenches, whatever you like to call them) and a small wrench. All of which came with the kit.

FIGURE 2. Between matches, all the teams have to fix their robots from the brutality of competition. In this photo, Team 468 is fixing their robot.