Experiment 1. Hardware 1.1 Fire-Fighting Robot Contest Maze at Trinity See document: arena.gif We arrived at Trinity Saturday, the afternoon before the contest. There were 3 mazes set up for testing, similar to ours, but to our surprise, the contest rules had changed at the last minute! Due to the overwhelming number of contestants, we now had to succesfully complete a pre-qualifying run in the maze to be allowed to compete on Sunday. We set our robot "Willitrun" into their maze to try it out, but all it did was veer into walls. Luckily we brought extension cords, tools, DMM's, a scope, and lots of parts! Testing on the bench showed that our object sensor sensitivity had somehow increased to double of what it was at Ward College. Why? Trinity had high pressure sodium overhead lighting, strictly a DC light source (not modulated by a ballast). Since our sensors were no longer swamped by 40 KHz flourescent ballasts, their sensitivity leaped! Since our algorithm was to meander towards the open space in the middle of hallways, it lost control when all sensors saw walls everywhere all the time! We increased R27 to 470 ohms (less IR LED intensity) which helped, but we had another problem: The sodium lighting swamped our flame sensors. Luckily we had some Kodak 87C IR lowpass filter material with us. This material passes 900-1000 nM and longer wavelength IR light but rejects all visible light under 800 nM. See document: kodak87c.gif We glued small pieces of it over all our sensors, the flame sensors and the object proximity sensors. After hours of fine tuning, we finally got "Willitrun" to complete a qualifying run - finding and extinguishing a candle - we were in! See document: ffc20.jpg 1.2.1 Flame Detectors The home-rolled flame detectors worked so well, we had a couple of people in the business ask about our design. The Kodak filter film really helped cut the ambient light interference. The modified AWG#10 splicing connector housings provided about a 30 degree aperture, wide enough to sense a flame by passing by it in motion, and narrow enough to zoom in on it off the front sensor. 1.2.2 Fan Lesson learned: Too much experimenting can be bad! After seeing the overkill some of the other robots had for fan horsepower, we decide to wire in another D-cell in series with our other two for more windpower. It worked - too well. In our first official run in the actual contest, Willitrun quickly found the candle in the 4th room, turned towards it, gave the fan a short test burst and blew out the candle instantly. The crowd cheered! The judge got out his ruler, our run was disqualified because we now could blow out the candle from 13" away - the rules say it must be within 12". If we left it alone, our algorithm would have seen the test burst leave the candle still lit, and would have moved in a few inches further before trying again, which would have made for a perfect run. See the next section "Optimize" for ideas on how this robot could be improved for next years' contest.
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