One Man’s Epic Quest to Build a Powerful Motorized Electric Unicycle
Here at Hackster, we feature a variety of impressive projects every day of the week. But, some of them truly stand out because of the sheer…
Here at Hackster, we feature a variety of impressive projects every day of the week. But, some of them truly stand out because of the sheer breadth of the undertaking. This 3,000W electric unicycle from John Dingley is one such project, and it’s noteworthy because it would have been a challenge for an entire engineering team to develop—much less for just one man.
Dingley, who goes by XenonJohn on YouTube, already had a lot of experience with self-balancing and electric motor-powered vehicles when he started this project back in October. Over the past several years, he’s built a self-balancing skateboard, and even multiple lower-power electric unicycles. But, this one is the most powerful — and ambitious — build to date.
Dingley started the project with tests on a massive electric hub motor rated for 3,000 watts at 72V. That should translate to somewhere around 3–4 horsepower. The motor is controlled through PWM (pulse-width modulation) from an Arduino Mega. Bench tests of the motor proved that it could run smoothly in both directions, which is obviously an important characteristic for a self-balancing vehicle.
He then moved on to constructing the welded-steel frame. It’s a cantilevered design that floats the seat over the single wheel. A linkage connects the handlebars to the rear of the frame with ball joints, so that turning the handlebars shifts the seat to one side of the wheel or the other. That allows the rider to reposition their weight to steer the unicycle. A small free wheel was also put on the front that acts as a safety to keep the unicycle from flipping forward under hard braking.
The upper frame and seat were constructed from motorcycle and aircraft parts that give the unicycle a sleek retro look. Because that ended up being tubular, Dingley created unique cylindrical battery holders from milled ABS plastic. Those slide nicely into the steel tube that makes up the upper frame, so the finished design looks graceful instead of bulky.
With the construction finished, Dingley was ready to take the unicycle out for some test rides. The first tests proved the concept, but the motor control wasn’t as smooth as he would have liked. Thankfully, after some PID (proportional-integral-derivative) motor tuning, similar to what you’d do for a drone, it was running much better. Dingley has only reached about 30% of max power for now, but even that looks like an absolute blast.