17) Solowheel-style hub motor Unicycle project 2011

I looked at the Trevor Blackwell unicycle, the Enicycle, the Focus Designs unicycle, the Ryno Motors one-wheeled scooter, the micycle and most recently the solowheel and decided that it was about time I built a unicycle!
There will be two footpegs each side so if I want to I can ride it with no saddle as in the solowheel example. The batteries will be fitted in one side and the electronics on the other. This means there will be no little box mounted above the wheel, making it more portable, more compact + lower centre of gravity.
For now the footpegs are welded on but eventually I will make them fold up flat on each side.
This also means I can mount roller skate wheels on end of each footpeg as "stabilisers" while I learn to ride the thing if I want to.
Here is the welded frame ready for testing of the accel/gyro inputs and motor controller.
The motor is a BRUSHED hub motor from an electric bike mounted in a 20 inch BMX wheel.
Although brushless motors are now more common in the electric bike motor world, I found an older brushed design as this is more like a normal electric motor nd canbe controlled by a normal type of motor controller.
By undoing 4 bolts the wheel/motor assembly can be removed from base of the machine (upwards in this image).
The gyro and accelerometer sensors are in the small black box (temporarily)
as close to main axle as possible. 

Testing unicycle motor controller

Early testing video before electronics were tidied up. 
MAY 2011: Not tight enough balance control so have now changed OSMC control to locked-antiphase. More on this to follow.
Have decided to add a unicycle saddle for now while I try to learn to ride it.
On hold.
Not enough torque at wheel to inspire confidence riding it. I suspect once moving along it would be OK actually but have strong feeling that if I continue with this one I will end up in the casualty department of the hospital I work in!
OSMC motor controller on left (designed for large combat robots).
Controlled by an Arduino which is reading the accelerometer and gyro.
Two potentiometers are present to adjust variables within the software, particularly the Proportional
and Derivative gains. 
3300 mAh 12V NiMh batteries x 3 are fitted.
These packs are 22cm long and all three fit in frame on opposite side to the electronics.
They are designed for radio control racing cars.
View of the control box modified to fit available space.