Author Topic: Arduino-based heliostat array  (Read 2378 times)

Brendan

  • New Member
  • *
  • Posts: 30
    • View Profile
Arduino-based heliostat array
« on: August 10, 2010, 10:09:30 PM »
Gabriel,

Wow!  I came to your site today and saw what you've done lately.  Really great work.  I'm on a very similar project and really appreciate it.  My work is at www.heliostats.org.  I'm looking forward to your code posts.  I want to incorporate them because I stink at coding.  I think your take on how to control motors from one arduino and motor controller is exactly right and I'm trying the same. 

Anyway, I hope to have more questions and more to offer in terms of a 'stat design soon.  I've got a Makerbot for parts and am waiting on the next version of the plastic extruder.  Maybe one of these days we'll all be working on thermal storage systems or high concentration PV.

Anyhow, thanks for your work.

Brendan


Gabriel

  • Administrator
  • Hero Member
  • *****
  • Posts: 656
    • View Profile
Re: Arduino-based heliostat array
« Reply #1 on: August 12, 2010, 05:59:29 AM »
Thanks!

Your site looks pretty cool so far. It will be neat to see what you come up with next.


The code should be up soon. It has a been a lot of work to document it, but it is mostly done now.

I've actually been holding off on uploading it because my heliostats hadn't really been working quite right. It was the most perplexing thing. Absolutely everything was exactly as it should be, but the reflection still tended to drift.

I must have double checked the output from the program a hundred times, and everything seemed perfect.

Yesterday I finally sat down and figured out exactly where the reflection was supposed to be by using a laser level, a tape measure, compass, and some trig. When I manually moved the mirror to where it needed to be and then just let it do its thing for the rest of the day, it did much better.


I'm starting to think that my compass isn't entirely accurate since my heliostat seems to be about 3.5 degrees off from where it is supposed to be along the azimuth.


I guess getting these things aligned correctly is a lot more tricky that one might guess. Oh well, I think I have it mostly figured out. As soon as the sun comes out again I'll be able to do more to get it aligned better.


Have Fun!
Gabriel


Jon

  • Jr. Member
  • **
  • Posts: 93
    • View Profile
    • YouTube
Re: Arduino-based heliostat array
« Reply #2 on: August 18, 2010, 02:05:18 PM »
I seen Gabriel mentoned a compass.  You probably know this but maby some people out there don't.  A standard/common magnetic compass will naturally point to the "magnetic pole" and not to the "north pole / true north ".  You have to look on a map to find out where the current magnetic pole is and basically you'll get an idea of how many degrees off your compass can be.  Last I looked a few years ago, the magnetic pole was in about North-Central Canada, and my compass was about 15 degrees off then since im eastward of that here in PA.   Sometimes maps will indicate how many degrees off a compass can be from true north.

Perhaps the best way to set up a compass is to go out at night and find the North-Pole Star ("Polaris") and align your compass, sundial, or anything else with that.
« Last Edit: August 18, 2010, 02:09:51 PM by Jon »

Gabriel

  • Administrator
  • Hero Member
  • *****
  • Posts: 656
    • View Profile
Re: Arduino-based heliostat array
« Reply #3 on: August 18, 2010, 04:38:30 PM »
Yes that's definitely true.

One thing I experimented with to double check my compass was to first drive a pole into the ground which I then made plumb. Once that was finished I was able to use a program which gave the current position of the sun to figure out when its azimuth equaled 0 degrees. At the same time the azimuth is at zero, the pole's shadow runs parallel along north and south.

It seemed to work as it gave the same north direction as my compass.

It's a pretty neat trick.


For the last week I haven't had any sun to test my heliostats out with. Hopefully I will be able to make a video of them in action once it comes out again.

Fall semester starts next Monday for me, so hopefully the sun will come out soon because I will probably be much too busy past that point to do any work on my site.