The Electric Unicycle’s only control is the on-off switch. The rider controls everything else by shifting his weight. You lean forward to accelerate, lean backwards to brake, and gyrate your arms wildly to turn. With a little practice you can get more graceful and keep your arms mostly by your side.
The unicycle balances itself using a simple feedback loop between a solid-state gyroscope and the wheel motor. When it detects itself tilting forward, it runs the wheel forward to keep it vertical. When it detects itself tilting backwards it runs the wheel backwards. It does this so rapidly (200 updates per second) that it feels perfectly smooth. This is really the same thing that a conventional unicycle rider does with his legs.
Under British law, having only one wheel a unicycle does not count as a bicycle and can therefore be ridden on the {pavement,sidewalk}; I have no idea whether this machine would therefore be not merely exempt but actually irrelevant for the purposes of road tax.
You can download the complete software from the site, and the mechanical fabrication drawings are available in Postscript. The MPEG Video is pretty cool, too.
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