Question 1: What was the general strategy or plan behind your bot design?

I built Stretch as an adjustable robot. My idea was to have different parts, which could be adjusted, including the length (distance to light sensor) and width (distance between wheels).

Question 2: What technologies/mechanisms did you use?

The software was the same I used for my other robots, so I could just work on the robot hardware.

Question 3: What was the most challenging aspect of construction?

The robot was actually rebuilt from scratch in about ten minutes the night before the event, while my wife was packing for the trip. The hardest part was trying to explain why I was re-building a robot, while she was packing my clothes!

When I finally had a chance to test it, I discovered it was geared up 1:5, instead of geared down 5:1. Luckily, it was easy to fix.

Question 4: Are there any special features you care to talk about?

Stretch was designed so I could change the gear ratio, by sliding a couple gears on an axle. It could go between 1:1 and 5:1. The only time I really used that was in the Accurate Stop event (the only event Stretch was not in the top two finishers). I could also adjust the light sensor (which I never did) and change the width of the rear wheels. The time I did adjust the wheels in the continuous line event, it performed much worse.

Question 5: What surprised you about how your bot behaved/performed during the event?

Stretch got very lucky in the continuous line event, when it made it past all the dashes and got to the end, at which point, it turned around and ran the course backwards, then forwards & backwards AGAIN (before getting stuck on the edge of the paper).

It was also lucky in the closed loop event. (usually) The course had 5 loops, and they were the exact size of Stretch's turning radius. Sometimes, I caught the turn wrong, and had to loop around for a second attempt.

Looking back, Stretch didn't need to have the adjustable gear ratio. It didn't help, and would just cause more friction.