I enjoyed the disco bike light project I recently completed. For that project I took a design idea and ran it through a process similar to what we do for clients that hire us for electronic engineering services. That process made writing about the design a little more structured and I ended up with something I could test and use.
I’m going to do that again, but this time with a dual axis solar tracker controller/tracker.
We’ve blogged before about a dual axis solar tracker, and even created a couple of prototypes. The block diagram above describes a kind-of universal dual axis motor controller. With it you could control both motors regardless of the feedback mechanism they required. You could also use a low cost accelerometer to verify that the motors are in a desired position.
That block diagram, and oddly enough the disco bike light project, started me thinking about a dual axis solar tracker that used just the accelerometer for feedback and got rid of the extra “stuff”. This design’s block diagram might look more like this…
I’ve added a light sensor, some manual controls, and some kind of programming interface. But I’ve removed most of the feedback, as we will try to use just the accelerometer to determine panel position.
Tracking the sun can get pretty complicated. You can maximize light incident upon the panels while following a pre-programmed movement that’s calibrated to the time day and time of year. A system like that adjusts for seasonal changes and could even modify its track due to foliage, adjacent vehicles, or buildings. But I want to shoot for something a little more simple. After all, what I want to find out is whether or not I can use a low cost accelerometer to get the job done.
So my design will check to see if it is day-time. If it is, it will follow a predetermined path as defined by accelerometer readings. Here’s a simple flow chart.
I know our mechanical system uses a 24V and a 12V brushed DC motor. The current load is pretty low, but I would guess it peaks at around 8 amps and is more likely in the 3 amp range during a movement. Also, the system needs to be outdoors, so an extended temperature range is required of the ICs I select.
This is the design I’m going to blog about in the following weeks, and we’ll see how it goes.