Electric vehicles are fertile ground for innovation because the availability of suitable motors, controllers, and power sources makes experimentation accessible even to hobbyists. Even so, [John Dingley] has been working on such vehicles since about 2009, and his latest self-balancing electric unicycle really raises the bar by multiple notches. It sports a monstrous 3000 Watt brushless hub motor intended for an electric motorcycle, and [John] was able to add numerous touches such as voice feedback and 1950’s styling using surplus aircraft and motorcycle parts. To steer, the frame changes shape slightly with help of the handlebars to allow the driver’s center of gravity to shift towards one or the other outer rims of the wheel. In a test drive at a deserted beach, [John] tells us that the bike never went above 20% power; the device’s limitations are entirely by personal courage. Watch the video of the test, embedded below.
We covered [John]’s previous unicycle which used a brushed DC motor and chain drive; the main factor limiting the use of brushless hub motors was the availability of a suitable speed controller. For use in a self-balancing vehicle, the speed controller must provide solid control in both forward and reverse directions, but most are set up to drive forward only. [John] found a solution in the form of a speed controller designed for an electric boat, but still needed to do some integration work to turn PWM into a smooth analog voltage by hand-soldering an LTC2644 DAC. Power comes from twenty LiFePO4 cells in the cylindrical fuselage above the wheel, and switches and knobs provide fine-tuning of the control software. Since the build lacks any sort of digital display, an Arduino using the Talkie library from [Peter Knight] provides an 80s-style computer voice to speak alarms and status to the driver. Even though assemblies like the motor and speed controller were key parts of making the build possible, there was still a lot of work needed for integration and in software.
[John] really knows his stuff; he has a resource page on self-balancing vehicles in general, and here’s a link to a YouTube playlist of the build process of this latest unicycle in particular. Great work!