Self-balancing unicycle

Self-balancing unicycles at 'Paris sans Voiture' (Paris without cars), September 2015.

A self-balancing unicycle (also electric unicycle) is an self-balancing unicycle personal transporter. The rider controls the speed by leaning forwards or backwards, and steers by twisting the unit using their feet. The self-balancing mechanism uses gyroscopes, accelerometers in a similar way to that used by the Segway PT.

Theory of operation

Most commercial units are self-balancing in the direction of travel only (single axis) with lateral stability being provided by the rider; more complex fully self-balancing dual-axis devices also need to self-balance from side to side. The control mechanisms of both use control moment gyroscopes, reaction wheels and/or auxiliary pendulums and can be considered to be inverted pendulum.

History

Trevor Blackwell demonstrates his prototype

Early experimentation

See also Monowheel

A hand-power monowheel was patented in 1869 by Richard C. Hemming^[1] with a pedal-power unit patented in 1885.^[2] Various motorized monowheels were developed and demonstrated during the 1930s without commercial success^[3] and Charles F Taylor was granted a patent for a 'vehicle having a single supporting and driving wheel' in 1964 after some 25 years of experimentation.^[4]

Commercialisation

In 2003, Bombardier announced a conceptual design for such a device used as a sport vehicle, the Embrio.^[5] In September 2004 Trevor Blackwell demonstrated a functional self-balancing unicycle, using the control-mechanism similar to that used by the Segway PT and published the designs as the Eunicycle.^[6] In November 2006 Janick and Marc Simeray filed a US patent for a compact seatless device,^[7] the same year that Aleksander Polutnik demonstrated a first two-axis balancing human-ridable unicycle, the Enicycle. In 2008, Focus Designs released the first commercially available self-balancing unicycle^[8] and RYNO Motors demonstrated their prototype unit.^[9]

Shane Chen of Inventist launched the compact seatless 'Solowheel' in February 2011^[10] and in the following month concluded a licencing agreement with the Simeray brothers^[11]^[12] and filed a patent relating to the device^[13] which was challenged by the Simeray brothers in a related patent application filed in 2015.^[12]

Late in 2015, the Ford Motor Company patented a "self-propelled unicycle engagable with vehicle", intended for last-mile commuters.^[14]

Popular culture

A self-balancing unicycle was described in 1969 in The Man From R.O.B.O.T., a short story by science fiction author Harry Harrison.^[15]
Fenton Crackshell, a Disney character, is depicted wearing a robotic unicycle suit as Gizmoduck.
Demolishor, a Decepticon from the 2009 Transformers sequel, whose robot mode is a gigantic robotic unicycle.
The "tumblebugs" in The Roads Must Roll
The protagonist in the Flash browser game, Little Wheel.^[16]
Thor, fictional inventor of the wheel and the comb, of the comic strip B.C..
Securitrons from Fallout: New Vegas.