Rupert |
Mr. Glitch |
Both Rupert and Mr. Glitch shared the same drive train - an adder/subtracter made with two differential gears. Driving one differential would cause both wheels to turn at the same speed in the same direction. Driving the other would cause both wheels to turn at the same speed in opposite directions. Driving a combination of both added the speeds of driving them separately on each wheel - so one motor would drive straight, and the other would adjust turning. We found numerous advantages to this drive system:
Our sole method of navigation was line following. Shaft encoding would have been easier, but boring. A shaft encoder robot can only follow very fixed paths, and our entire strategy was based on a dynamic path. We used an array of 9 light sensors on the bottom of the robot to follow the lines, although usually only six were watched at a time. In lab, the sensors picked up the blue jail as black, and we coded for that. However, during the contest (under much different lighting) they picked it up as white. We didn't figure this out until after impounding, and thus couldn't fix it. It was frustrating to watch Mr. Glitch banging against a wall because he couldn't figure out he was in the jail.