One of the robot topics we discussed was navigation, and how the GPS is inconsistent and kind of bad at keeping track of our robot over, say, a 2-minute match. So, Pete brought up the idea of a mechanical mouse, using a small rubber ball and 2 (3?) rollers to measure how much it rotates, and theorized we could attach two of these mice to the bottom of our robot to give us accurate odometry.

While a single mouse would suffice to measure linear movement, we still need 2 to account for turning. Having two of these trackballs, on opposite sides of the robot, will turn in similar directions when moving in a line, and in different directions when turning, giving us a pretty accurate number as to what direction we're moving and how fast.

The GPS has trouble with small distances and consistency, and an odometer would have issues with moving long distances: so using both systems, they can usually fill out eachother's gaps and create a far better picture of the robot's motion.