Ver. 0.9.6 fixes a bug in the code which caused the altitude and azimuth of the heliostat to be calculated incorrectly for certain inputted angles. The entire “heliostat angle” algorithm was rewritten and tested throughly inside a computer simulation, so it should be good to go.

Code for the new Arduino IDE 1.0 has also been added.

As always, let me know if you encounter any issues.

The Open Source Sun Tracking / Heliostat project has been entered in the Build Lounge laser cutter contest. These contests are always a lot of fun since they inevitably introduce new individuals to your project. You can read about the contest and also view the contest entries by clicking the banner below. You can then vote (ideally for my project ) by selecting the the entry on the left side of the page and clicking the “vote” button. Thanks!

It’s been a fairly quiet around the site over the last several months as I have been busy with school. I’ve still been working on various projects, but just haven’t had much time to document them.

Over this winter’s break between semesters, I decided it was about time I finished the introductory video to the Open Source Sun Tracking / Heliostat Project which is shown below. It was a bit of a learning experience (aka a serious pain in the you know what) to put everything together, but overall it didn’t turn out too bad.

www.youtube.com/watch?v=QXtEDCK7GwY

If you remember Sid’s Sun Tracking Machine posted on this site a couple of months ago, you’ll no doubt recognize its design in these pictures at the Minnesota State Fair. The event itself is massive. Their website gives the number of attendees for 2011 at 1,769,782!

To quote the sign below,

This solar tracker follows the path of the sun throughout the day. Continual reposition of the photovoltaic panels and solar hot water system allows them to always directly face the sun and capture the maximum amount of sunlight.

This efficient solar array will produce about 2607 kWh of power annually, which is enough to power about a quarter of the electricity needed for the average, energy-efficient Minnesota home.

The 80 square feet of solar hot water panels will produce enough hot water to supply the average household with approx. 80% of their hot water needs.

A picture of the tracker from below, pointing at the sun

Side Shot of Solar Tracker

A picture of the electronics housing, with this site featured

One last shot of it and the surrounding area.

This page shows off a single machine sun tracking / heliostat electronics set up. You may have already found it, but, if not, there is a more elaborate electronics system here which includes things like shift registers for increasing the number of controllable machines, relays to allow multiple machines to be controlled with just one set of driver boards, and switches to change heliostat targets.

Not surprisingly more elaborate also means more complicated. To try and make life a little simpler, the system on this page leaves out some of the extra bells and whistles and instead keeps only the bare essentials. Should you ever wish to include some of the previously mentioned “extras” they can, of course, still be added later down the road.

There isn’t a whole lot of extraneous information on this page. Instead it focuses on an electronics system which is as “plug and play” as possible. The extraneous information, however, does exist on the Open Source Sun Tracking / Heliostat Electronics page. It wouldn’t be a bad idea for you to at least skim through it and focus on the parts which are only touched upon briefly here.

Program

Please note that the electronic system on this page requires a slightly different version of the Sun Tracking / Heliostat Program. You can download it by clicking the link below.

Arduino_SunTracker_V096_Simpler_Electronics

The only noticeable difference between this program and the one on the Open Source Arduino Sun Tracking / Heliostat Program page is the way the stepper motor driver board code is set up inside it, so you can still refer to the documentation there for learning how to use it.

Arduino IDE 1.0 (or higher) Code

If you have updated the Arduino IDE to 1.0 or above, you will need to use this program instead of the one above. Arduino_SunTracker_V096_Simpler_Electronics_Arduino1 (Alternatively, you can also download an older version of the IDE and just use the above program)

You will also likely need to replace the line “#include <WProgram.h>” at the top of the Flash.h file (download link is in previous section on this page) with the below syntax in order for the program to upload.
#if defined(ARDUINO) && ARDUINO >= 100
#include “Arduino.h”
#else
#include “WProgram.h”
#endif

Arduino

The first thing you will need is an Arduino microcontroller. There are a myriad of different types that will work, but I would recommend either the Arduino UNO or the Arduino Duemilanove.

RTC

The RTC (real time clock) is what allows your Arduino to keep accurate time. I’m using the one from Adafruit. The sun tracking / heliostat code given on this page is specifically set up so that the RTC can be easily plugged into the Arduino’s analog pins. The tutorial given on the Adafruit site for soldering the RTC together gives an example on how to connect the RTC in this manner. Below is a somewhat uglier picture that I took of the set up.

Limit Switches

The limit switches are used to allow the machine to reset its position. Here is a picture of the schematic. Note that they are wired normally open, or NO.

Here is a picture of a test circuit I built to make sure the limit switches were working before attaching them to my heliostat.

This picture shows a simple way of attaching the resistor in the above schematic to the Arduino.

Driver Board / Power Supply

Like the Arduino, there are also many different driver boards that will work with this system. You can check out the Wiring a Step/Dir Type Stepper Motor Driver Board to an Arduino page for more info on what I’m using and how to set it up. It is probably the most involved section of this system, which is why it has an entire page dedicated to it.

Stepper Motors

Most any type of stepper motor could probably be made to work with this system. Two things you should pay attention to when purchasing yours are holding torque, which is basically a measure of how powerful the motors are, and whether or not they are unipolar or bipolar stepper motors.

The amount of holding torque your stepper motors will require largely depends on the size of your solar machine. If you are building a mid sized machine (around one square meter of collection surface), I would say around 80 oz. inch of holding torque would probably be adequate. Of course, you might be able to get by with less if you can build an especially well balanced machine. On the flip side, having more holding torque means that you can get away with a machine that might not operate very smoothly. A lot of it depends on your building skills. Once you decide on how much holding torque you need, the next step is to decide on whether to get a bipolar or unipolar stepper motor / driver board.

If you buy a bipolar driver board, you can use bipolar and also unipolar stepper motors.

If you buy a unipolar driver board, however, you cannot use bipolar stepper motors because there is no way to wire a bipolar stepper to a unipolar driver board. Note: A bipolar stepper motor only has 4 wires while a unipolar stepper motor typically has 6 or 8 wires.

I recommend the bipolar driver boards because you can use both types of stepper motors with them. Also, bipolar driver boards only need four wires to hook up each stepper motor (stepper motors with more than four wires can typically be wired as a four wire stepper), which means that you will save on the cost of wire and also have a little less wiring to do.

Also take note that there is a ton of information on stepper motors available on the net. A quick Google search will give you more than you will know what to do with.

The End

That covers the bulk of the information for a single machine sun tracking / heliostat electronics system. Have a question? Did I leave something out? Go ahead and leave a comment below.

This page will show you how to wire a  step/dir type stepper motor driver board to an Arduino. The driver board used in this particular example is available from Avayan Electronics and has thus far proven to be quite superb.

Here is the link http://www.avayanelectronics.com/Products/AE-STPR8811/ae-stpr8811.html

Although commercial driver boards vary in their design, the general method of wiring and controlling them typically remains more or less the same. The one thing to watch out for though is to make sure you buy a stepper motor that is compatible with your driver board.

If you buy a BiPolar stepper motor driver, then you can use basically any stepper motor just by wiring it correctly.

If you buy a UniPolar stepper motor driver, however, stepper motors with four wires (BiPolar) will not work, but all the other stepper motor types will.

If I have a choice, I generally just go with the BiPolar drivers because there are only four wires to keep in order.

Driver Board Stepper Motor Test Code

You can download example stepper motor control code by clicking the link. Stepper Motor Test.zip The code itself is rather simplified, but will be a good, quick test to make sure you have your board wired correctly.

You will notice that I have the code set up to test two stepper motors sense I am using them to control a pan and tilt solar tracker / heliostat. This entire tutorial is slightly biased toward this tracker, but hopefully not so much so that you won’t still find it useful if the tracker is not how you came to this site.

The code is programmed to turn Motor 1 one full revolution forwards and backwards. Next, (if it is set up) motor 2 will do the same thing.

NOTE: A word of wisdom from someone who has learned it the hard way, if you were thinking of using the Stepper.h library to control your stepper motor(s), don’t bother because it’s not for the step / dir type driver board like we’re using here. You might have luck using the AccelStepper library though.

Wiring the Driver Board to the Arduino

For my particular driver board (and possibly yours too), many extra “features” are built into it. These features can be controlled through the various pins if desired, or simply left unused if not needed.

The first thing we’ll address is the VCC and GND pins. Here, the VCC pin on the driver board is wired to the 5v pin on the Arduino and the GND pin just goes to, well, GND on the Arduino.

Next, we’ll take a look at the Step and Dir pins. The Step pin tells the stepper motor when it is time to move one step, and the Dir pin tells it which direction to take that step. It is possible to wire these two pins to most any of the Arduino’s pins, but I typically just use pins 2 and 3 for the first driver board and pins 4 and 5 for the second.

This last pin to address is the Enable (ENBLn) pin. Not all driver boards have this one. It’s purpose, however, is to basically just turn the stepper motor on and off. This can be quite useful if you are trying to save power. In my case, this pin must be written LOW to turn the board on and HIGH to turn it off. It sounds backwards, but that is indeed how it is set up. I have my Enable pin wired to pin 6 on the Arduino.

Pin Recap (Driver Board On Left, Arduino On Right)

VCC  –>  5v
GND –> GND
Motor 1 STEP –> Pin 2
Motor 1 DIR –> Pin 3
Motor 2 STEP –> Pin 4
Motor 2 DIR –> Pin 5
Enable –> Pin 6

Note: When using multiple driver boards, it is possible for them to share Arduino pins. For example, 5v, GND, and Pin 6 can all be wired in parallel with multiple boards.

Controlling Step Size

It is oftentimes the case that you can control the step size of the stepper motor by changing settings on the driver board. You should check your driver board’s documentation to see how step size is controlled, but the one I’m using does so through jumpers (shown in the picture below).

A couple of reasons for controlling the stepper motor’s step size is for both increased precision and smoother (quieter) operation. Generally, the best step size for your particular stepper motor(s) can be determined through experimentation.

The various step sizes for my driver board can be seen in the picture below. One of the most important things to realize when changing the step size is that doing so also changes the number of steps required to move your stepper motor(s) a set distance.

For example, if I have a stepper motor which has 200 steps / rev written on the back of it, one would expect it to take 200 steps for the stepper to make one complete revolution. This would be correct if I were to use “full” stepping, but, if my driver board was set on “half” stepping it would actually require 400 steps to make one complete revolution.

If it was on “quad” stepping it would take 800 and if it was on “eight” stepping it would take 1600. You may have noticed that the full, half quad, and eight options are essentially just multipliers. Full stepping essentially just multiplies by 1 which means that it basically does nothing to the number of steps / rev printed on your stepper motor. Half stepping multiplies by 2, quad by 4, and eight multiplies by 8.

Wiring Driver Board to Stepper Motor

Wiring a stepper motor can either be really easy or really confusing. If you buy a stepper motor that has a decent data sheet you can access, and also if your driver board has good documentation, then figuring out how to do it shouldn’t be too overwhelming.

My general recommendation in this department is to just Google it because there is already a ton of information on this subject. Suffice it to say that there are just too many variations to really fit in this tutorial.

I will give you this one warning however, don’t start wiring the stepper motors to the driver board until you have turned off power. The driver board can be damaged if you do so.

Power Supply

For any stepper motor of a decent size, the Arduino itself will not be enough to power it. This is easily remedied by adding DC power supply to the mix. Driver boards can typically accept a range of voltage inputs, so check the documentation for yours to find out what it is. The power supply I’m using was originally for an old HP printer. It has a 18V output and is capable of up to 2.23A.

VREF Adjust

VREF, if your driver board has the option, essentially allows you to control how much power goes into your stepper motor. Too much power, and your stepper motor will overheat. Too little power, and the thing might not have enough torque to get the job done.

The documentation that comes with your driver board will likely contain formulas which will allow you to calculate the exact optimum VREF setting you should use. I generally go for the less scientific (lazy) approach and just start low and keep increasing until I reach a happy medium of adequate torque without too much heat.

I generally let the motors run for at least half an hour before determining that they aren’t overheating. I also check the driver board chip itself with a temperature probe to make sure that it also isn’t overheating.

A good temperature range for both the stepper motor and the driver chip can be determined by looking it up in their data sheets.

The actual VREF is typically set with a variable resistor. There should also be a place to test the VREF with a multimeter. Black probe goes to ground and red probe goes to the VREF contact point. As the variable resistor is adjusted, the measured voltage should also change. The higher the voltage, the greater the power to the stepper motor.

NOTE: Your driver board, like mine, might need to be hooked up to the Arduino first so that the enable pin can be controlled to turn the board on.

The End

Finally, we have reached the end of everything (relevant at least) that I can think of adding to this page.

If I missed something, leave a comment below.
Thanks!

The solar panel sun tracking machine in the above picture was built by Sid Frantz. Sid and I have been communicating back and forth by email in an effort to get the Open Source Arduino Controlled Sun Tracking / Heliostat System to work with his machine. There have of course been hurdles, and there are still likely more to come, but, for the moment at least, it seems to be working!

This page contains a quick overview of the tracker’s mechanics and electronics.

Update:

More pictures of one of Sid’s sun tracking machines at the Minnesota state fair have been added at this link. Very cool! www.cerebralmeltdown.com/2011/09/18/sids-sun-tracking-machine-at-minnesota-state-fair/

More On Sid Frantz

As you may be able to guess from the pictures, Sid does in fact build and sell these machines (along with other things) commercially. His email is sid {at} fgsinc {dot} com. If you have an idea for a project but lack either the equipment or skills to make it happen, he’s the person to contact.

Gear Reduction System

This tracker consists of 4K watts worth of solar panels. Obviously, it is one hefty beast. The azimuth gear reduction system consists of a 60:1 gearbox which then goes to a 12:112 sprocket. The altitude gear reduction system is the same but with an additional 5:1 chain drive.

Electronics

The picture below shows the electronics layout. On the left, you can see the power supply. At the top are the driver boards for the stepper motors. You can also see the Arduino microcontroller in the middle. This particular variant is the Arduino Pro.

Here is a close up shot of the above.

With the Arduino removed, you can see the RTC module used for keeping the time along with its battery backup. There are also convenient outputs for the stepper motors and limit switches.

Share Your Project

Even though he isn’t a programmer,  Sid has been able to help me a great deal with the Arduino Sun Tracking program simply by relaying to me the odd behaviors that he has experienced with his particular set up. As always, if anybody has a project they would like to share, please send it along by either commenting, posting it on the forum, or by emailing. It’s more helpful than you might realize. Thanks!

Here is a Heliostat project which, if I have my facts correct, was designed and built by industrial design students from Amsterdam. The site itself features several open source solar builds and is definitely worth keeping your eye on in the future.

One thing is certain, the design of this heliostat is a heck of a lot better looking than what I made.

Unfortunately, they haven’t been able to get the tracking figured out yet. Some of my code from the Arduino Sun Tracking / Heliostat project was used for the main tracking calculations, but they made the switch from stepper motors to DC motors with a Hall sensors to provide position feedback and ran out of time before being able to get it to work.

Interestingly enough, Brendan at Heliostats.org has been working on this exact thing. It certainly would make for a great addition to the Open Source Arduino Sun Tracking / Heliostat project if someone was able to get this idea to work.

Owning a CNC machine means that you must inevitably find ways of dealing with the endless stream of dust that is created when cutting material. This dust can easily be controlled with the use of a shop vac. The downside, however, is that the dust filter inside the shop vac can only handle a limited amount of the stuff before it is overwhelmed and has to be cleaned to regain good suction. This is where adding a cyclone dust separation system can make your life much easier.

With such a system, most of the dust never even makes it to the shop vac’s filter because it is collected in a separate container located before the shop vac. This container also adds the advantage of making the task of emptying out the collected dust a lot easier.

I’ve seen several of these systems scattered across the web. The commercial versions similar to the one on this page range from around $20 to $100, and some of the DIY versions I found looked like they would take more effort than I felt like putting in.

I finally ended up just designing something from scratch. It turned out to be really simple to make. And guess what, it actually works!

Here is a top view of my DIY dust collection cyclone separator. The dust filled air enters through the shop vac hose on the right. It then spins around in a cyclone. Because it’s heavier, the dust ends up in the bottom of the bucket while the now largely dust free air continues out the the left tube to the shop vac.

To make this dust collection system, I started out with a lid from a drywall mud bucket and cut two 2.5″ holes with a hole saw. The input side (right) has a 90 degree PVC elbow attached to it. This is what helps create the cyclone. I used caulk to help seal around the PVC and hold it in place. I also used some weather stripping to seal around the shop vac hose.

The output side (left) consists of just the shop vac hose shoved down into the 2.5″ hole.

Here’s how much dust is in the bucket after several hours of operation. This bucket is deeper than your typical 5 gallon one. It’s somewhat hard to make out in the picture, but there is about 4″ of dust in the bucket.

Here’s a picture of the inside of the shop vac. Notice how there is hardly any dust in it. Also, keep in mind that my shop vac wasn’t exactly clean to begin with. It will be a very long time indeed before I have to empty it out.

I’ve been quite happy with this DIY CNC dust collection separator’s operation so far. It’s amazing how such a simple thing makes my life so much easier.