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Hi,

Yes, that's right :) I'm still working on the code to improve accuracy.  Sorry for the delayed reply, i thought this thread was kind of dea, but I'm happy someone finds this useful.

let me know what kind of details you are interested in, I'll be glad to share anything
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Heliostat Projects / Re: Super low-cost heliostat with ESP8266 for WiFi control
« Last post by moritz on May 29, 2017, 01:01:50 AM »
Hi Nick and Gabriel,

I have that bi-weekly maker / diy radio show called "Netzbasteln" on german national public radio Deutschlandfunk Nova. See netzbasteln.de for all past projects. Quite some of them contained an ESP8266, which i really felt in love with. Same goes for the idea of a heliostat which I wanna build in one of the two next shows - which is already next sunday - or also two weeks later. I am really enthusiastic and grateful for the great work you did here, Gabriel!

For my heliostat I already welded the frame (using a bicycle fork), now its up to the motors (will use steppers and Pololu A4998 / 8825 drivers I already used for a CNC and and an Eggbot) and the code. I want to use an ESP8266 (propably Wemos D1 Mini) and program a small webserver on a hotspot that allows you to control everything in a web-browser. Nick wrote:

I'm sharing all my code with Gabriel as I go along, and I'm hoping that at some point we'll have a single source tree that automatically recognises its hardware, and compiles the correct code for the Uno/Mega/ESP8266.


My question: would you mind me (and two friends who are professional programmers and would help) joining this effort and send me the code you are already working on? Guess it would even be best to put it on github and work on it together there! I can do that if you want.

Some work for ESP8266 has already been done - but i assume its a very old version and we should start over anyway:
http://cerebralmeltdown.com/forum/index.php?topic=854.msg3400#msg3400

Many greetings, really looking forward!
Moritz
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I haven't tried it in awhile, but I was able to install it on my Windows 10 machine and use it without any issue at all. Thanks!
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Thanks for the program Gabriel. Does your software work on the latest Windows 10 and does it still work properly?
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Hi luiklodwig,

I really like this idea because it creates closed loop system, such that accuracy of mechanical parts doesn't play big role.
As I understand, camera is stationary, not moving, pointed towards the target, right?

I plan to build something similar, but instead of camera use light sensor mounted at target window. Because in my case, distance between mirror and target window is only around 2 meters.

I would use time of day for coarse positioning, and once achieved use light sensor for fine adjustments

Can you provide more details of your implementation?
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Heliostat Projects / Re: Worm thoughts
« Last post by Paul L on April 23, 2017, 07:58:57 AM »
Just a quick update on this idea:  It works really well as far as moving power is concerned.  I hooked up a 5v 28byj-48 to a common tuning peg, and attached it all to a lazy susan bearing which would act as the azimuth.  I stacked a three foot tall pile of textbooks on it, and it had no problem moving the whole thing, which was really amazing to me seeing how the running voltage was 5v, and roughly 200mA if I remember correctly (I did this a few months after the original post, so it's been awhile).  I'm guessing the books weighed thirty lbs.  It's slow but it works, and the resolution was pretty darn good!  The only drawback is the play when the motor stops - it's really sloppy.  There would have to be some kind of resistance to pull against the heliostat to tighten everything up.

I did take pictures with all the pieces I used, but I can't seem to find them now....I'll post them if I come across them.

This would most likely be the cheapest way to build a heliostat  - I think the motors, couplings, and tuning pegs came to less than ten dollars - per heliostat!  And it's not just a toy, it can move practical amounts of weight, including, I would guess, full sized mylar mirrors (4'x8').     
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Heliostat Projects / Re: Super low-cost heliostat with ESP8266 for WiFi control
« Last post by Gabriel on April 15, 2017, 10:28:27 AM »
This is a bit of a delayed reply, but you shouldn't need anti-backlash nuts. What would be more helpful is more of a say anti-backlash heliostat. So, the altitude and azimuth motions would be pulled in one direction by say a spring or a weight. That would help eliminate any wobble.

Also, It's something that I don't think I have documented well, but the closer you can keep the mirrors towards the axis of rotation the better. There will always be some drift as they get further and further  away, which may or may not be the reason for Paul's drift.

It's technically something that could be compensated for in the software, but it would add yet one more variable to the settings as I believe that you also need to have the distance to the target programmed in. I haven't gotten around to figuring out the math to compensate for it either.

I don't think it would take much to run a heliostat, or heliostats, off of solar. In the grand scheme of things they don't use much power. All they do is move part of a revolution forward and backward in each axis once a day, which amounts to practically nothing for smallish machines.

I actually managed to pick up a solar kit which even has the outdoor box for the batteries and charge controller for $10 dollars where I work, so I am planning on doing pretty much the same thing. Whenever I finally finish 3D printing all of the parts for it. Only 40 more hours of printing to go. ;)

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Thanks for all that info Paul - very helpful!  :)

Do you think I'd need an anti-backlash nut on my lead screws? They seem popular on CNC cutters/3D printers, but perhaps that precision isn't needed in this application?

I love your idea of using glued nuts for pivots! Simple and very economical.

I'm sharing all my code with Gabriel as I go along, and I'm hoping that at some point we'll have a single source tree that automatically recognises its hardware, and compiles the correct code for the Uno/Mega/ESP8266.

The EasyDriver board does indeed have its own regulator which can output 3.3V/5V, but apparently it can't manage a high enough current to drive the ESP8266 when it is using WiFi. I also want to completely disable the EasyDriver boards unless I need the motors to move, so for those reasons it makes sense to have the separate MP1584 powering all the logic.

I don't know how practical it will be to run the heliostats off (solar-fed) batteries, but I'm trying to minimise the power requirements so I can hopefully try that in the future.

Cheers
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Heliostat Projects / Re: Stepper motor rotary to linear motion.. HOW?
« Last post by Paul L on April 04, 2017, 04:20:22 PM »
You're right emimina, the newer versions are using worm gears.

They are definitely the better way to go (easier to set up, better range or motion).  But of course, they cost more.

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Heliostat Projects / Re: simple linear actuator instead ??
« Last post by Paul L on April 04, 2017, 04:15:55 PM »
Hi Emimina,

   The Sunharvester code has written is specifically for stepper motors - so the short answer is no, you can't use a linear actuator.  I think you may be able to do it, but it would require a bunch of re-coding adding some kind of optical encoder to the motor itself.  Hope that helps...
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