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Messages - Paul L

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1
That looks great, and I'm excited to see it working!  I'd order a board, but I'm strapped for time and have never done SMD before, so I'll have to pass, but I'm interested in buying a fully finished one when you get to that point!  Keep us updated and keep up the good work! 

Just a thought, and it would require a board redesign, buy if you use A4988 driver boards (I think they're similar to the Easy Driver in specs), you could shrink the size of the board (or put 4 drivers on it and control 2 separate heliostats) quite a bit. 
   
Cheers,

Paul

2
Heliostat Projects / Re: Worm thoughts
« 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').     

3
Heliostat Projects / Re: Stepper motor rotary to linear motion.. HOW?
« 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.


4
Heliostat Projects / Re: simple linear actuator instead ??
« 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...

5
Hi Sheffieldnick,

  I would say yes, a counterweight would be a great idea; 10kg is pretty heavy for NEMA17, so if it's not balanced properly, they might have a tough go.  You shouldn't have to worry about wind movement when the steppers are off - the leadscrews are essentially self locking.  I used casters with the wheel taken off for the "screw nuts".  I took pictures and posted them in the forums here: http://cerebralmeltdown.com/forum/index.php?topic=305.msg1583#msg1583

For this design to work properly, you have to have everything plumb and level, with super accurate measurements and as little play in the parts as possible.  If any of those things are off slightly, you'll notice in the end, so take your time and do it right the first time!  Even my best build had a little bit of drift, and I tried damn hard to be accurate.  This is one of the reasons why I think worm gearboxes are the way to go - way less room for user/build error.  But if you're trying to keep costs to a minimum, this is the way to go!

Very cool that you'll be using the ESP8266 and the added features you've added in - it'd be great if you posted your code once you have it all up an running.  Also, ff I recall correctly, the Easy Driver has a 3.3v/5v linear regulator on board for external power supply, so you'd be able to use that to power the ESP8266 rather than the MP1584. 

Best of luck, and keep us posted!

6
Heliostat Projects / Worm thoughts
« on: March 09, 2016, 09:42:35 AM »
Hi Everyone,

   It's been a while since I've posted, so I thought I'd dust off the keyboard and share a few thoughts here.

   I've been hoping for the last few years that someone here would come up with an accurate, easy to do diy worm gear for all these stepper driven heliostat designs.  It's becoming increasingly clear that it's not going to happen, and that it's not a trivial task do accomplish, so I am begrudgingly abandoning hopes of that happening.

   I've been thinking again lately of the tensegrity design I had posted on the forums a few years ago (http://cerebralmeltdown.com/forum/index.php?topic=357.msg1504#msg1502) and am thinking about building a small test version.  What originally put me off ever pursing it years ago was the problem with the "bail" not working as the original designer had intended.  What I plan to do now is mount small steppers directly on the tensegrity structure where the bail would have gone.  Most likely 28byj-48 motors since they are readily available and inexpensive.  Since they run with very little power, I plan on chaining a handful of them together for azimuth control and running several mylar mirrors simultaneously, while another stepper controls all or their altitudes,.

  The problem with this idea, I imagine, then would be the holding power of the 28byj-48's.  A large mylar mirror with a small gust of wind would throw alignment of these small motors out.  My solution is to use another fairly common piece of equipment - guitar tuning pegs or gearheads.  They're cheap, small, readily available, are self locking and have great holding power. The gearing ratio on them would also bump up the accuracy of the heliostat considerably - I believe the most common gear reduction is 12:1.  The are remarkably accurate when under tension, but there is some slop when changing direction (at solar noon say, or while pulling off the limit switches)but I assume one could account for those few extra steps in the coding.  Graphtech, a company out of Vancouver supplies tuning pegs with even higher gear ratios - I've contacted them - gave then a brief overview of this site -  and they've graciously sent me a few 39:1 tuning pegs to experiment with.  They seem to be of better quality than the standard pegs I've purchased off ebay, though I assume they'd be quite expensive to buy. 

While I haven't had time to play with this idea yet, I hope to "fairly" soon.  That being said, I'm expecting my first child in...a few days ago, so I'm guessing my free time will be in short supply in the near future.  Just thought I'd throw the idea out there and see where all of you will take it, since it could be applied to any stepper heliostat design, not just 28byj-48s.  Hopefully someone on the forums here will give it a go and post about it!

Cheers,

Paul

7
Quote
Anyway, I suppose that same webcam set up could be used to track the position of the sun and move the sun tracker or heliostat accordingly. That would get rid of the GPS altogether. I'm not sure how accurate it would be, but it's an idea.


It would, wouldn't it?!  All you'd need is a single board computer like a Raspberry Pi (or this $9 competitor - http://arstechnica.com/information-technology/2015/05/move-over-raspberry-pi-this-startup-is-building-a-9-computer/) that can run openCV and a webcam.     

Here's a relevant paper if anyone wants to take a look - http://www.jmest.org/wp-content/uploads/JMESTN42350280.pdf

Also, having it be able to track clouds and predict sun availability would be a really cool addition - great idea!

New to me and could be of interest to others: pcDuino.  It's a single board computer with arduino pinouts so you can just plug existing shields into it!   

8
Heliostat Projects / Re: worm-drive vs linear-actuator vs belted-pulley
« on: September 12, 2015, 08:44:48 AM »
Hey Gabriel!

    I've been scratching my head for the last two days - how exactly would you get a linear actuator system to rotate a full 360?  The only mechanism I could imagine for the job would be a Scotch yoke, so the program would have to be modified to change direction at solar noon.  Is that what you were thinking? 


9
Heliostat Projects / Re: worm-drive vs linear-actuator vs belted-pulley
« on: September 07, 2015, 09:54:17 AM »
Hey Ben!

    Nice to see you being so active on the forums lately - I like the enthusiasm!  :)  Of those three systems, I've used the worm drive and linear actuator.  Both these systems do what they're supposed to do - track/redirect sun.  But there are strengths and weaknesses to both. 

Linear actuators - The best thing about this setup is the relatively cheap, readily available parts you need to build it.  Once all the bugs are figured out - its a fairly robust system.  But setting it up can be a pain - the measurements have to be dead on and there's a lot of re-adjusting.  It also has limited range, which is my biggest problem with the setup.  Can be a little noisier than worm gears - I apply oil to the lead screws periodically.

Worm gear systems are tougher to find, and way more expensive than linear acutator systems.  On the plus side, setup is way more simplified, movements are quicker and there is no limit to the range that it can track.  I managed to salvage and modify two worm drives from an old electric wheelchair and they work really well.  Worm gears are also self locking, so you don't have to worry as much about misalignment due to high winds.  And mine are in a sealed unit, so it's really quiet and can handle the weather.

Belt n pulley I've never tried, but I'd be a little concerned about the holding power of such a system in high winds since it's not going to self lock, and you cant depend on the holding torque of the stepper, which is powered down between moves with Gabriel's program to save power.

The big companies use slewing drives, which would, in an ideal world,what I would use.  Basically, they're large self contained worm drives that can take alot of weight.   

Winner in my books?  By far a worm gear setup.  Nicer to look at, easier to set up, quiet, efficient movement, gears are self contained and protected from elements, self locking.

10
Oooo, I love thinking of new ideas/suggestions!!

Here's what I think: a GPS and compass addition would be great - especially for a portable system.  Having a feature where it self levels (or maybe compensates for being off level) for  would also be dreamy, but hard/costly to setup.  As far as GPS modules go, cost really shouldn't be a concern - you can get them on ebay for 11.00, free shipping and they work super.  You could also remove the RTC if you had a GPS, so that would save some costs there.  If there was a set design, preferably with worm gears, the homing microswitch could be removed with the addition of an LDR/LED array.  Just turn the heliostat on, let it get the gps position.  The program will already know the position of the sun depending on the GPS location, so if the steppers are then programmed to move to the brightest location in the sky according to the LDR/LED array and then set that as the position of the sun, that's all it needs to know.  A self setting heliostat; no figuring angles or cardinal directions!  That's be great...
 
Any step that removes human input is a step in the right direction.

I like dual acting steppers - though not super important.  Agree with solardude, it would look cooler.
Not sure what the benefits would be with 32 bit mc's?  More accurate?

I'll think on this for a while and may add more later!

Cheers,

Paul   

11
Think Tank / Re: Another wireless networking option: ESP8266
« on: August 06, 2015, 08:30:42 PM »
hey alobo,

   sounds like you're making some progress porting it to the esp8266!  keep up the good work, and keep us all informed -  it's an interesting project and I'm interested in where you'll take it!

cheers,

Paul

12
Hey Zimirken,

    I've love to get my hands on this print and try it out - I may have to download it and try printing at the local makerspace, since I don't have 3d printer as of yet.  I like that you're using these cheap, small motors.  I've only played with them a briefly, but was impressed by their torque and low cost; I'm actually surprised you have to use more than 5 volts to get them to work.  I modified mine to increase torque as per this video:
 
https://www.youtube.com/watch?v=jHLyJbNgcDo 

They seemed like they would be strong enough to move a fairly large mirror....

Good work, and thanks for sharing!

Cheers,

Paul

13
Think Tank / Oh, deployable things.
« on: January 12, 2015, 05:34:35 PM »
Hi All,

   I've had this idea bouncing in my head for awhile and I feel like it needs to be let out so others can have their say about it.  Let's collaborate!!!  Bring on the ideas!!  I could describe it much more eloquently, but I just want it out for now so sorry for the uglyness that is about to follow.  So here we go: Wouldn't it be cool if it was possible to have heliostats non stationary - mobile in other words?  Imagine, going anywhere you want, pushing a button and then having a heliostat roll on out, find a sunny spot for itself and then self-orient to your set target?  If it gets shaded, it would self move to a new and sunny location.  That's what I've been thinking, but on a grander scale, in a backyard.  Imagine a swarm of micro-helostats, all with sensors for self leveling, orienting and sun seeking.  It really wouldn't be too hard to do I think.  Deployable mirrors could be added, using mylar epoxied to snap band trusses so it could be rolled away in bad weather.  Each heliostat would communicate with each other via cheap nRF24L01 boards.  All use cheap, but incredibly strong 28byj-48 steppers and cheap 3 DOF sensors.  Have them all solar powered.  Waaaaaaaaaaaaaaaaattt?  Am I crazy here?  Now, that'd be cool!

Paul

I think it'd be great anyway, to have a dozen of these things running around my yard.         

14
Heliostat Projects / Re: Heliostat Design(s) [Work in Progress]
« on: November 14, 2014, 02:15:30 PM »
Nice work Gabriel!

   I'm wondering how you've made each mirror adjustable - are you using the same system in your first pics in this post with the adjustable blocks of wood with the threaded rod running through it? Set and tighten?   I've wondered awhile about making adjustable mirrors and the only other system I've seen is the one used in the "solar death ray mirror - I can't find the link now, but they used several small mirrors with a dab of silicone to hold it in place, and then used screws on the four corners to set the angle of the mirror.

Anyway, good job!

Cheers,
Paul

15
Heliostat Projects / Re: Heliostat Design(s) [Work in Progress]
« on: October 08, 2014, 08:11:31 PM »
Hey Gabriel!

    Well, I have to admit that I've been anticipating this post with bated breath for awhile - you always seem like you're making leaps forward on your design, and this is no exception.  Kudos!  Let me know when you have them for sale to the general public! :)  Fingers crossed that everything goes well for you - this build looks awesome!

Cheers,

Paul

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