Electric unicycle

An electric unicycle is a self-balancing personal transporter with a single wheel. 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
The problem of creating a self-balanced unicycle, a self-powered unicycle that balances in all three dimensions, is an interesting problem in robotics and control theory. The theoretical work on the unicycle problem is complemented by the work in the construction of real mechanically mounted unicycles.

First, a self-balanced unicycle can be considered as a nonlinear control system similar to a two-dimensional inverted pendulum with a unicycle cart at its base: however, there are many higher-order effects that participate in the modeling of the complete system. The rotation of the drive wheel itself can provide one-dimensional control (ie forward and backward): control in other dimensions generally requires other actuators, such as auxiliary pendulums, reaction wheels or gyroscope moment control attached to the main pendulum of the unicycle.

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.


The wheel is in a plastic case with a handle for carrying the device. On the top panel there is an on / off button, a battery charge indicator and a charging connector. To the right and to the left there are symmetrically two steps on which the rider stands. Footboards at monokolos, as a rule, develop for convenience of transfer of the device. Inside is a powerful blisks (250-2000 watts) electric motor, the gyroscopes that keep the balance wheel, and rechargeable batteries. The monowheel has neither the back nor the front side, the operation of the device is completely symmetrical.

The principle of work
When power is on, electronic gyroscopes and accelerometers begin to change the torque of the motor so that the wheel housing tilted by the pedal through the pedals restores the horizontal position. The longitudinal equilibrium is achieved by “approaching” the device under the center of gravity (the rider with a monowheel), and the dynamic transverse equilibrium is due to the centrifugal force of rotation that occurs when the wheel is tilted to the sides. Thus, the monowheel is controlled by moving the center of gravity (tilting the body) forward, backward and sideways. With a full stop, the user of the device must lean on one leg.

Unlike other personal vehicles, such as electric scooter and segway, the monowheel requires more training time. Some early models of mono-wheels were equipped with two wheels, as well as additional removable wheels for pedals, in order to simplify training, but this approach did not find wide application. It is necessary to consolidate the skills in order of priority: get up on the pedals and dismount (control the wheel with one foot), pick up speed and brake (shift the center of gravity), steer to maintain transverse balance, turn. Training takes from an hour (with an experienced assistant) to 2-3 days (completely independently).


Early experimentation
A hand-power monowheel was patented in 1869 by Richard C. Hemming with a pedal-power unit patented in 1885. Various motorized monowheels were developed and demonstrated during the 1930s without commercial success 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.

Today there are many different models of monocolaces. Most of them have similar parameters:

Weight: 8.5-29 kg
Maximum speed: 10—50 km / h
Travel distance per charge: 10-240 km
Wheel diameter: 10, 12, 14, 16, 18, 22 inches.
Optional: Bluetooth-speaker, communication with a smartphone to indicate speed, power and battery charge, to set restrictions, lights.

Electric scooters, including monowheels, cannot be used on highways in some countries. The use of monowheels requires wearing protective equipment for roller skates, because of the danger of falls.

In Russia, riding on a monowheel is equal to a pedestrian

The danger of riding a monowheel is hitting an obstacle: in this case, the wheel slows down dramatically and does not keep pace with the rider leaning forward by inertia, which causes it to fall. From this point of view, the most powerful mono-wheels are the safest, since the high instantaneous power allows the wheel to accelerate sharply and “drive up” under the person leaning forward.

Another danger is a sharp acceleration / tilt forward, especially when the monowheel is already traveling at maximum speed. Working at the limit, it does not have time to develop even more power and turns off. In this regard, the higher the developed speed, the more dangerous the wheel is during sharp acceleration at high speed. This is compensated for only by limiting the maximum speed in combination with the excess capacity of some models.

Nevertheless, thanks to a simple design, in which there is no huge number of mechanical components, the monowheel is a safer transport than, for example, an electric scooter, which allows you to develop a high speed, which often breaks the steering wheel, collapses the axles of the folding mechanism, shock absorbers, the wheel diameter is smaller, which also adversely affects when the wheel gets even in small pits and encounters with obstacles. In addition, the safety of the monowheel adds its amazing maneuverability, which can not be compared with any other vehicle of the same class.

In 2003, Bombardier announced a conceptual design for such a device used as a sport vehicle, the Embrio. 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. In November 2006 Janick and Marc Simeray filed a US patent for a compact seatless device,. In 2008 RYNO Motors demonstrated their prototype unit. In January 2009 Focus Designs demonstrates electric unicycle to Segway inventor. In Oct 2010 Focus Designs published a video of an electric unicycle with hub motor and a seat.

Shane Chen of Inventist launched the compact seatless ‘Solowheel’ in February 2011 and in the following month concluded a licensing agreement with the Simeray brothers and filed a patent relating to the device which was challenged by the Simeray brothers in a related patent application filed in 2015.

Late in 2015, the Ford Motor Company patented a “self-propelled unicycle engagable with vehicle”, intended for last-mile commuters.

In April 2018 Ryno Motors, publishes video about invention of single wheel motorcycle.

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.
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.
In The Lorax, protagonist Ted Wiggins uses a self-balancing unicycle with handlebars.
Thor, fictional inventor of the wheel and the comb, of the comic strip B.C..
Securitrons from Fallout: New Vegas.

Source from Wikipedia