ENGINEERING “CURLING” COMPETITION
Objective:
Create two automated vehicles to travel 27 feet, which are no bigger than 12” diameter and no heavier than 3 lbs. Design and build time was 5 weeks. Each team would create two vehicles. Each team would battle each other team. Closest robot to the center of the 3 concentric target rings is the winner. Per round, each team would alternate sending a vehicle down the track, toward the target.
Design Decisions:
I'd never used an Arduino before, but decided this would be a good project to learn on. I'd thought about DC motors with rotary encoders to measure the distance traveled, but understood the added complexity of a separate brake mechanism, and wanted to keep things simple. I chose a stepper motor because it intrinsically rotates in countable increments, and if the coils are left energized, some braking action can be achieved when stopped.
The shroud was designed to be exactly 12 inches in diameter, to exert the maximum “reach” into the target zone. The rear sides were a shallow incline to prevent an opponent's vehicle pushing ours. The front was more steeply sloped to allow pushing of opponents. Ground clearance was designed to be 0.1” to minimize the potential of an opponent scooping/lifting the vehicle. Weight was positioned near the front wheel, to maximize traction, both for pushing and braking. Rear wheels spaced as far as possible, and connected directly to each other via a solid axle to assure a straight and predictable path.
No steering mechanism was designed, but rather the vehicle was aimed manually with a small red-dot laser sight. An RGB LED was included inside the translucent shroud to allow the operator to visually see a countdown (green -> yellow -> red over 10 seconds) with which to aim the vehicle .
All wheels were lathe turned so that they would be maximally round, on-size, and with very concentric axle bores. Mounting brackets for rear axles and stepper were laser cut, with secondary holes and countersinks produced on the mill.
Results:
This thing was incredibly accurate and consistent! No other team scored a single point against it, and it managed to push opponents out of the way when necessary. Opponents were not, however, able to
displace this vehicle. We easily won the competition.
SECOND VEHICLE
The rest of my team didn't really seize the opportunity to design and build the second required, so i build something more traditional for this type of challenge in around 9 hours. This vehicle worked well, but not nearly as well as the first vehicle. The build was done entirely on the fly, with little measurement or planning. The cad drawings were for documentation, rather than the design process.
