Here’s a second design, called the JeeBot Mini – no less:
The first JeeBot used servo’s but that’s not really such a great fit for self-balancing. This one uses miniature (and pretty weak) motors, directly driven by the ATmega’s I/O pins. The small socket is for the same Memsic 2125 accelerometer as on the original JeeBot, but placed at a 45° angle to use both X and Y axis together.
On the right is a tiny 100 mAh LiPo battery – plenty for simple trials. No gyro, no regulator, and no resonator (so far). No JeeNode either – just a serial FTDI interface and a bare ATmega168 chip running the LilyPad bootstrap @ 8 Mhz, straight off 3.7 V from the battery.
I’m waiting for some wheels for this thing. Am not sure the wheels will turn fast enough to regain balance once detected. If not, maybe raising the center of gravity by extending the “chassis” upwards will help. Or bigger wheels. Or both. Or maybe the design choices are hopelessly wrong already… we’ll see.