Tiny, Solar Powered, Light Seeking BEAM Bot (Mini Photopopper)
Introduction: Tiny, Solar Powered, Light Seeking BEAM Bot (Mini Photopopper)
Today I will show you how I made this tiny little robot!
Since I first mentioned the word in an Instructable and got a couple questions about it, every new BEAM Instructable I feel the need to explain my understanding of the term "BEAM robotics". Wikipedia will tell you that BEAM stands for Biology Electronics Aesthetics and Mechanics, and though I have heard conflicting theories about the name in the past I do feel that BEAM embodies these aspects. It is a style of electronics developed in the late 90s and early 2000s using mostly found components in ways that are quite elegant or clever, in order to create the most basic intelligent robots.
This particular style of robot know as a photovore, phototrope or photopopper, meaning it uses some very simple logic to locomote toward light.
Making tiny photopoppers has been done before, indeed even I have tried (in the video you can see my attempt from 2018 built on a PCB I designed), but I am really happy with how this particular one turned out and am excited to share the process with you all!. I have included links to other examples below, but I wanted to make this new bot for a couple reasons.
1. I knew I could do better than my predecessors just because these (relatively) new IXOLAR monocrystaline solar panels from digikey seemed to have incredible specs and oh boy did they work awesome in the end! Solar panel efficiency is tied to surface area so this means when you shrink a panel in both dimensions, you get much much less power. But these IXOLAR panels are 25% efficient which is crazy! And not only that. they claimed to work fine in partial shade or even indoors which is something that other monocrystaline and polycrystalline cells tend to struggle with. 51
You will notice in the video that I actually have another photopopper using very similar parts but I used an amorphous cell for that one because I wanted it to work indoors (where amorphous cells shine) and I was still unaware of how good these monocrystaline cells had become. Again, you can see for yourself in the video, but the new cell is smaller than the old one, AND it pops around twice as fast indoors! Though this may also have something to do with the lower trigger voltage for this new bot =P.
2. This point also ties into the solar panel power conundrum but I actually wanted this guy to move like bigger photopoppers so I was happy to sacrifice some miniaturisation for good functionality and again, I think this project achieved that. The other examples either wouldn't move too well or are still a little big but I really wanted to try make this guy as similar as I could to bigger photopoppers...just smaller! I could maybe have used smaller parts like some BPW34 cells, and some more clever circuitry/special motors to deal with lower voltage, really Im not sure, but more than anything I really just wanted this guy to be as small as possible and still move "properly"
Photovore here on instructables using a flexible amorphous cell and vibration motors:
https://www.instructables.com/Nano-Photovore-BEAM-...
And a great, albeit short, write up on a much more similar photopopper to this one:
https://www.fetchmodus.org/projects/beam/photopopp...
A super cool example using 8x BPW34 cells and an aluminium cap. Seriously, if you haven't seen <PERSON> videos check this out! Such incredible production value... but still a little big for my liking ;).
https://www.youtube.com/watch?v=3RKTKfLhuPE
All of these were great inspirations for if this was even feasible as well as for specific parts (I will touch more on components in the next step).
Step 1: Parts
2x Voltage monitors: MCP112-195
For this particular photopopper I chose to use a voltage monitor that triggers at ~1.9V, with the added voltage drop in the diode and the voltage added by the photodiodes, this means that the circuit triggers when the storage cap reaches around 2.3V. In my previous attempt I used MCP112-270s that trigger at 2.7V which meant the capacitor needed to charge to around 3.1V! This is unnecessarily high for the motors I used but may be right depending on your other component choices. 832