Single-Axis Solar Tracker Mechanical Part

Hi arduino users,
I have to reproduce a mechanical design like this one but I can't make it..actually, I don't know how to start with...
This is the assembly I want to clone as it fits exactly my needs. I need to make a solar tracker for a college project controlled using fuzzy logic. I know very well what I have to do in theory but when it comes to practical I get myself completely off the map.
Here's the link Solar Tracker
I can't figure out how the guy managed to connect the servo motor's shaft to the threaded rod where the panel is fixed, or I guess it works like that because the images are a bit disturbed.
These are the parts I have right now:
Motor Driver Motor Driver
2 Pololu Dc Motors like this: Pololu Dc Motors
3 LDR's
sensor screening system(something offhand), Arduino Uno and the academical Kit(servo motor, temperature sensor, LCD, leds, wires and all the stuff)
The project will be implemented at an academical level so the tracker will be tested using a flash(not the sun itself) just like in the above clip. And I think this photovoltaic is more than enough in order to light a couple of leds(just for emphasizing the tracker's role, you know), here's the link: Photovoltaic
I guess I will need a couple of triangular brackets, some sort of threaded rod. Anyway, I don't know how the assembly was created. Thanks in advance for all your help, I'd really appreciate any commentaries being good or bad! Cheers!
PS: What I really need is this..."Go to the closest store and get these pieces: photovoltaic, wooden/plastic/plexiglas support, triangular brackets". Then, go and look for a threaded rod that will connect the 2 heads of the brackets and on that rod stick the photovoltaic...this is what I'm looking for as I'm zero when it comes to put into practice!!

last1left23:
I have to reproduce a mechanical design like this one but I can't make it..actually, I don't know how to start with...

Why are you using DC motors and L298 drivers instead of the much simpler servo. Servos are electrically and mechanically very simple.

I need to make a solar tracker for a college project controlled using fuzzy logic.

You are not the first person on this Forum to use the phrase "fuzzy logic" in relation to solar tracking.

To the best of my knowledge the motion of the earth relative to the sun is one of the least fuzzy things in the universe.

Very simple code (perhaps 10 lines) will keep a solar panel facing the sun based on the input from a pair of LDRs.

...R

Well, good point...I don't see any problem in using the servo but how can I connect the servo's shaft to the photovoltaic, can you guide me through this? Is there a simple way...do you understand how the guy in the video connected the parts? I have to implement with fuzzy logic, this is what the paper has to contain...I wrote a lot in this direction. If I can't implement it with fuzzy logic, lately I will implement it classic but the first option is fuzzy because this is what my instructor asked for.
But this is my last problem, the first problem is how can I obtain that system of articulation so that when the servo's shaft spins it will also spin my photovoltaic...this is my main problem. Can you guide me in this direction? Thanks in advance!
PS: I'd rather use the servo's shaft coaxial with the shaft where the fotovoltaic will be sticked, somehow...maybe connect them through some kind of small tubing, you know? I will try to schematize what I'm trying to tell :slight_smile:

I don't see any problem in using the servo but how can I connect the servo's shaft to the photovoltaic,

The video shows the servo shaft connected to the mounting post, not the PV panel.

You can buy pan/tilt servo platforms: https://www.servocity.com/html/pan_tilt_roll___accessories.html

You don't need to connect the servo shaft to the solar panel. You just connect the servo arm to the panel.

Make a simple pencil drawing showing how you think the panel will be mounted and showing how the servo is connected and post a photo of the drawing.

It will be easier to help you with that as a starting point.

I'm sure there are lots of examples on model airplane forums showing how servos are connected.

...R

Hi,
Welcome to the forum.

What is your electronics, programming, arduino, hardware experience?

Tom.... :slight_smile:

1st Assembly

Identical to the video's assembly
This is how I want it to look in the final but I can't figure how to connect the servo's arm to the mounting post which I guess also includes an arm...so that whenever the servo's arm spins itself it will also spin the arm who is sticked to the mounting post where the PV cell stands.

The other solution is much more complicated...I thought I might attach the servo to the left bracket such that the servo's shaft will be connected to the shaft made by some threaded rod, you know! And on that threaded rod I will stick(hot glue gun) the mounting post which holds the PV cell.
If the drawing is not good please don't hesitate to tell me where the mistake was and I will do my best to make another one...Thanks a lot for your help!!
Ps: It was pretty complicated to me to transfer a 3d drawing into a 2d one but I hope I made myself clear with what I want to obtain and how I thought the servo will be connected! Thanks again!
High resolution hand drawing link:

Photo

Well Tom...
I'm okay with Arduino and control part but I don't have what to control as I still don't have the assembly ready.
So my Arduino experience is pretty well but my hardware experience is minimal...This seems to be the hardest part as I've never seen or implemented a solar tracker like that one although it seems to be the simplest to implement.
Once I get to make the assembly so that I can send PWM commands to the servo and the solar panel will start spinning, then there will be no future problem.
I will make some measurements in order to find out what the universe of discourse of the fuzzy is and fuzzify the system. But there's long path till that moment :slight_smile:
Maybe if I can find somewhere in real life some kind of articulation system and connect it to the servo's arm...I don't know, I really need everyone's help!

Image from Reply #6 so we don't have to download them. See Image Guide

...R

Guys, after watching that video many times and consulting with many people I came to this conclusion.
I guess the servo's shaft is locked somehow so that the servo itself will spin around its own axis and as the motor is attached/sticked to the back of the mounting panel holding the PV cell, it will also spin the solar panel itself. So I guess the servo's arm role is to lock the servo's shaft rotation and the rotation is transmitted back to the motor itself. Is it feasible?
I've never actually tried to start the motor and when it starts spinning it's shaft I will hold the shaft and see what's hapenning but the first guess is that the rotation will be transmitted back to the motor itself...I have to test that though!
I will try to redraw the 2 ways of implementing this:

Schema 1

Schema 2

Schema 2 is just a threaded rod anchored between the 2 brackets's hole and the mounting post will be sticked using some bridles. Then I will connect the servo's shaft which has screw thread with the threaded rod I was talking about, but this the second option on my priority list, the first being the one above :)...
Thanks a lot guys for assisting me and I'm sorry for not reading the image posting rules before!!!I'm waiting for your sugesstions:)

How can I use these parts to my advantage?


I couldn't see the bottom image in Reply #8 yesterday because my broadband connection was slow. (Please reduce images to 640x480 before uploading them)

Now that I can see the image the way the servo is fitted seems very straightforward and simple. Why won't that arrangement suit your project?

...R

Would you mind if you could describe it in a few words? I just want to see if the way you describe the way the servo is fitted and the way you see the whole thing complies with my understanding of the things.
I guess is the servo's shaft that's locked and as a consequence the rotation is transmitted back to the motor itself. As the motor is glued to the back of the support, it will also spin the PV panel.
If that's the case I have 2 problems:
How can I assure the servo can move the panel(for not being too heavy, you know). Looking into servo's electromechanical specifications?
How about this panel? I found it in my own country, Romania and it's not too expensive about 13 euros including delivery fees. Here's the link: Photovoltaic_Panel_3V
I'd really like to know how do you think that PV panel will fit my needs and my needs consist in cloning the assembly from the youtube video if it's possible :slight_smile:
The second problem is: Is there a second shaft, holding the panel? I can't understand quite right what's happening at the right end of the assembly, you know! Thanks for everything!
This weekend I'm going to set my a** to work and planning to finish it till 9-10 June.

Looking at the bottom photo in Reply #8 it seems to me that the body of the servo is fixed to the underside of the solar panel and the arm of the servo is fixed to the non-moving frame.

I presume there is a second bearing on the other side of the panel to share the load with the servo.

If the solar panel is balanced it probably does not need much torque to rotate it. In any case you can get some very powerful servos. You could even have two servos one on each side as long as you program them to move in the correct directions.

You have not said what you want the solar panel to do? I have been assuming this is just a demonstration of the ability to make the panel point towards the sun and that the amount of electricity it produces is irrelevant.

...R

Yes, you assumed quite well.
First option is to display the output voltage of the solar panel to an LCD and emphasize tracker's contribution.
A second option will be to use a voltage regulator and light the number of leds the voltage allows me to do...the same, to emphasize the tracker's role.
But I don't want a cigarettes pack-sized panel, you know! The panel I've just ordered is the one from the previous post and their dimensions are: 23x20cm...
Servo's are the best option as I can control them very easy using Arduino and there are already many implementied libraries and coming more.
I still don't know how to connect the right end without using a second shaft, you know! Maybe you could guide me through this last part of the mechanical assembly :slight_smile:

last1left23:
I still don't know how to connect the right end without using a second shaft

Neither do I. Use a second shaft - or something equivalent.

If you still have a problem post a diagram showing what you think you should do.

...R

A couple caveats,

  • solar panel open voltage does not change too much across a wide light intensity variation. Stronger light makes them give more current, that's what you need to emphasize.
    The most obvious way to show it works is just to move the light around and see it turning the panel towards it.
  • If the panel's balance axis is not very well centered, the servo can draw more power than the panel is providing, just to apply the needed torque to hold position. I guess for a student project the overall efficiency does not matter too much.

bafta!