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Wednesday, May 18, 2011

I'm Back Again!

Well hello everyone!

It's really been a long time since I've last updated.
For the past few weeks I've been busy working, while on the weekends helping build the Solar team's new car Celeritas.

Finishing the car was a real time crunch. The race was in Houston, Texas on April 14-16 and believe me when I say it was close. We literally finished coding major components of the car on the trip down there. Luckily the 22 hour trip gave us a lot of time to focus.

We managed to get the code to a working condition once we got to the paddock area, but there was still plenty to do. We had a few major body adjustments to the car, and some minor brake spacing issues to work out. but in the end it all came together. We finished the race with 1st in our class. We also managed to get 2,200 MPG equivalent!

You might have noticed I said equivalent. Well in reality, our solar car runs off of electricity using an electric hub motor. So we have to manually monitor the amount of energy flowing from our batteries to our motor to calculate the energy consumption versus a gasoline powered car.
Thankfully, in the past year, due to the increase in electric vehicles on the market, the SAE determined that there are officially 33.7 kilowatt hours (kWh) worth of energy in one gallon of gasoline. You can run some numbers backwards and see that we consumed about 65 kWh of energy, and in the total run, we calculated our motor to be about 80% efficient. That's impressive, considering internal combustion engines run at less than 50% efficiency.

You can read more at our website at
and you can also read plenty of great articles by googling Purdue Solar Racing.

Well it was a blast, but what am I doing now?

Its currently the summer for me, and I'm not taking a break anytime soon. I have classes through August, then its back to work again. Luckily though, I have a bit more free time in the near future, and I plan on bringing back some old projects and knocking a few off my list.

Earlier today I dusted off the Arduino board and started working on my solar tracker again.
I uploaded the code to the board and started debugging. First thing I noticed is a slight mistake in the code. because of the slight variations in the components, the two voltage readings from photoresistors will almost never be equal for an extended amount of time. I had to add a tolerance value into the selection statement in order to get the servo to sit still long enough to be useful. I can always show you the code. Let me know if you want to see it!

Next step is to package it all together. I started a rough CAD model of how I'm going to fit everything onto the servo. I decided I want to have the Arduino board spin with the solar cells. This will (I think) minimize the amount of wiring required to connect everything. Because most of the components will then be spinning, that also lessens the number of wires getting wrapped around the servo spindle.
That last statement might be irrelevant though. Either way I'm going to have wires getting wrapped up, and one wire could be as bad as 10.

Soon I'll upload a video of the project so far. I may also make a video showing how to calibrate a continuous servo.

And on a side note, when I moved into my apartment in Lafayette, I was a bit cramped on space and I wasn't able to pack the Bucket. The linux adventures are going to have to be put off until I make a second trip to get my stuff. I guess that leaves more time for the Arduino!

How 'bout you guys? Do you have any projects you've started recently? Any ideas? Or have you been doing anything interesting the past few months?

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