Solar Robot

On Sunday I spent the afternoon on my deck outside working on a project that I had been wanting to do for a long time. Make: 06 featured some simple and fun robotics projects that seemed like a good starting point for getting more familiar with soldering some electronics circuits. I ordered a simple BEAM kit similar to the one in the magazine from Solarbotics in Canada for $12.50 plus s+h, and got all my soldering equipment at radio shack for 25 bucks. This bot soaks up solar energy, stores it up in its capacitors, and then releases the charge when it reaches a certain voltage in order to power its motor. It was a freeform circuit, meaning I just soldered one piece to the next in sequence until it was complete; no need for prototyping, and no circuit board to fit components into. It was a difficult process, and I worked very carefully. It took me a couple hours to attach four capacitors in a ring around a small motor, and to assemble a simple 1381 solarengine circuit and attach it to the motor. I then soldered some wires to the motor and the tiny solar panel included in the kit, and practically jumped out of my seat when the motor started spinning. It took me a second to realize that I had done it, and then I just started laughing like a supervillain. It took me a while longer to complete the robot's structure, and make it unique. I bent and connected three paper clips to form a bumper ring and solar panel support. I soldered a dime to the top support to provide a platform for the solar panel, and then just stuck it on with some putty. Because of the dime, I named it "The Liberty Spinner" Later, I attached a pencil lead to each of the capacitors with some putty and set it on some paper surrounded by cups and under a lamp in order to have it draw an image.

It gets around by spinning a small rubber nub on the bottom of it, which gives it a twitchy, tippy, rotational motion. Under intense light, it will activate the motor every second or so. It's really fun to watch it go, because it will move until it bumps up against something, and then slowly work its way around it. You can see it moving around in this photo gallery. When it gets stuck, it will often wiggle itself loose after a few dozen twitches. With the pencil drawing it made, I could get a sense for its overall behavior, without having to watch it for the whole three hours it took to draw this. The darker circles are the outlines of the cups that I traced just to show where the obstacles were. The smudgy marks are from the chalk pieces that I attached first, but swapped because they were too tough to balance and not well defined enough. I also moved one of the cups because it kept getting stuck between it and the lamp base, which was just a bit shorter than the bot's bumper ring. It's neat to see how far it could reach into the corners, and how it spun its way around some of the cups, leaving a jittery concentric arc.



This was a very fun and satisfying project. It has me really excited about the future projects I'm planning. I think I'll start with an "Eggbot". I got a tutorial on it by its creator when I attended this month's meeting of the Twin Cities Robotics Group. Man was that ever a great time. I can't wait for the next one.