Why not a 6 year update?! This first hub motor electric uni build was simple and reliable and convinced me that non-balancing pedalable electric unicycles, really, work, great. At the time it also convinced me that I needed a higher pedal gear ratio to take advantage of the motor's output and the higher speed capbility. That lead to a small myriad of even increasingly complex uni projects with free spinning cranks, chain drives, CVT's and IGH's. Interesting in their own right, but also plagued by their own complexity.
In the end I started to miss the raw simplicity and reliability of the original fixed crank build and decided to dust it off this past week. Upgraded the controller to a Phaserruner FOC and built a small rack for holding a set prototype potted batteries with 18650 cells, but otherwise there was really nothing to do. The thing just works and is a joy to ride. Why did I leave it hanging in storage for the last 6 years!?
The Phaserunner is much smoother than the original custom-made trapezoidal drive controller that I had on it earlier. Normally that would be a good thing, but on a build like this the buzzing sound of the motor provided good tactile feedback on how hard the motor was running. Wih the Phaserunner, you have no idea unless you look at the CA display whether you're getting like 100 watts or 1000 watts of assist. So going up a hill you easily forget how much work the motor is doing and then on letting go of the throttle are in for quite the suprise when your legs have to pickup the slack or you'll go flat on your face.
It's also clear from riding around again that the throttle is not at all the optimal control input for an electric assist unicycle. You normally want to free your hands now and then for balance, and needing to be tethered to a handlbar is annoying. There are two approaches that I want to try next on this:
Torque sensor on the cranks: This would work awesome I'm sure and would natuerally let you amplify braking torque when going downhill as much as forward torque going up hill. But adding a torque sensor to a build like this won't be very easy.
Grade hill sensors: This has the advantage of potentially being much easier to implement than a torque sensor. Instead, you would have distance sensors (either optical or ultrasonic) on the front and back of the unicycle, and measure how far away the ground is from each case. That would provide the control electronics an idea the grade hill you are riding in order to produce a motor torque that cancels it out, giving increasing power the steeper the climb and regen braking on the downhills. It would also have the benefit of providing stabilizing feedback control if the unicycle does start to fall forwards or backwards.
Previously competed in the Suntrip race on a back to back tandem solar powered row/cycle trike
. 550 watt solar roof, dual Grin All Axle hub motors, dual Phaserunner controllers, 12 LiGo batteries, and a whole wack of gear.
Now back in Vancouver learning to be a dad with my Big Dummy Frame (yes This One
, thanks ES!) with GMAC 10T rear hub motor, Phaserunner controller, and 52V 19Ah EM3EV pack
My website: http://www.ebikes.ca
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