Sun Tracker

thingiverse

This is something my daughter and I utilized as a sun tracker. The basic concept revolves around attaching four light sensors (we employed photoreistors) in each quadrant; as the light drifts off-center, it casts shadows on the opposite side. This allows maximizing the values of all sensors to point towards the brightest spot. Our design includes slots for dropping in the sensors and letting their leads exit at the back. It also features a hole down the center that can be used for calibration - the light coming through this hole projects a circle when pointed directly at the light source. I've constructed it at various heights, with taller models being more sensitive to small changes in angle but causing a lot of seeking; on the other hand, shorter models are more forgiving yet less sensitive. We found that black filament works best in avoiding reflections. Additionally, I have included my Arduino sketch, which may be considered naive but suited our purposes; however, it causes quite a bit of seeking around the optimal value when using typical photoreceptors. To test it out, try attaching two servos together with the sensor at the top to create a 2-axis tracker, as seen in the attached photo. For best results, print it with black filament, one shell layer, and 100% infill.