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Heliostat Prototype #2

Here is my second heliostat prototype. It's one major improvement over the first is the way the stepper motors are set up to move the mirror. This prototype uses a simple threaded rod / lever arm arrangement instead of the worm gear setup I had on the first one. The worm gears on the first one worked well enough, but they are hard to make from scratch without a CNC machine, so I decided to omit them in order to make it easier for people who don't have one.

Another improvement is not in the design but the software used to run it. I am now using the Sun Tracker program to do all of the calculations and also to control the stepper motors.

Now, there is something that I need to say about this heliostat. It never worked (ARRGH), and I cannot for the life of me figure out why. Everything checked out, but, for some reason, no matter what I did the reflection from the mirror would not stay on target. Within a couple of hours, the reflection would drift away and miss the target completely.

I must have checked everything 100 times at least, but never had any luck. I finally decided to just scrap it and hope that whatever the problem was would disappear with a fresh design, which it did by the way.

I am going to assume that I just messed something up instead of blaming it on the gimbal design. Granted, I can't really say that it wasn't the gimbal design, but I honestly don't see how it could be at fault.

Why I Scrapped the Gimbal Design

In any case, it has some other problems as well. For one, you have to change the dimensions every time you want to use a different sized mirror. I wanted to build several heliostats, and all of my mirrors are different sizes, so I would have to figure out the dimensions for each one separately.

It also seemed like the gimbal design would be much harder to align when using multiple mirrors. If you look at the picture below, you'll see that there are two sides that need to be plum while at the same time making the mirror itself level. While doing just one mirror, this might not be such a big deal, but I planned on doing several chained together so that they could be controlled with just two stepper motors. Trying to keep multiple mirrors aligned seemed very time consuming.

 

 

It wasn't a complete waste though. I was still able to use it to code the new threaded rod / lever arm feature in the Sun Tracker program.

After scrapping heliostat prototype #2, I was able to put together the third one in no time at all. Believe it or not, it actually worked. Check it out on this page "Heliostat Prototype #3". 

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