Wait, part 6? I never thought I'd get that many. On the other hand, breaking the SDS into small parts was inevitable: all that awesome can't be contained in one post.
How much awesome? Well, so far we've seen a plasma-guided rocket, aerodynamic bicycle farings, a life-size remote control and motion base, an SUV car wash, and an autonomous oil-spill cleaning robot. Is that enough awesome for you?
Well, maybe for you. BUT NOT FOR ME! Today I'll be showing you the EVs I saw at the SDS.
One group had made a solar-powered electric boat. I've exploded an electric motor by over-revving before, and with the way speedboats seem to come out of the water all the time, I was interested in how they solved this problem.
Turns out, they sidestepped the whole problem by NOT GOING THAT FAST. Yes, they were participating in a race, but that kind of speed is just ridiculous. Their prop never came out of the water.
Which is also how they avoided the other big problem with boats: waterproof seals. They did have a waterproof mount, but it didn't work well for them. It put too much drag on their prop shaft. Luckily, the shaft went through the hull well above the waterline, so they just replaced it with a custom mount, lubricated with grease. Voila! Problem solved.
Their controls included the same potentiometer box I used in Silent E, but their motor was a lot different. Mine is a series wound brushed DC motor; theirs is a brushless DC pancake motor, which requires a more complicated controller. Works fine, though:
All in all, I was very impressed with the solar-powered boat. I hope to see more interesting solar stuff in the future!
It seems that every SDS must include a hybrid golf cart. One year, there were two, one in series and one in parallel. This year's was built on the cannibalized remains of a cart from a year or two ago, according to the students.
Given its heritage, I had to wonder what made it worthy of a senior design project. Apparently, this one uses regenerative braking (really, just a function of the controller, but what the heck) and allows you to switch between modes on-the-fly: you can drive fully electric, fully gasoline, or hybrid.
They had a problem with the chain tension, and were considering several solutions; until then, they couldn't get past about 10MPH with the electric drive enabled. I recommended a tensioner, like you see on 10-speed bikes (but bigger of course). They'd considered that idea, but they didn't really have enough money to implement it. They were actually thinking of just welding a bar in place, which would be noisy, but would work.
Yeah -- until friction quickly destroys the chain, the bar, or both. I'm not really impressed with this hybrid. But that's okay; I expect it'll be cannibalized for next year's cart. :D
Well, that's all for today. Next week, I'll wrap up with the multi-touch table, the iPad-controlled amplifier, the mine-clearing car, the wi-fi blood pressure tester... oh, yeah, and the electronic beer pong table. College students. Whatcha gonna do?!?