Self-balancing unicycle

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Used in Paris

A self-balancing unicycle is a unicycle electric vehicle that assists the rider in staying upright by using an electric motor and gyroscopes controlled by a computer that is fed data from accelerometers and other sensors.[1] As of 2015, several models were commercially available.[2] They are commonly referred to as Electric Unicycles and EUCs.

Control theory of the self-balancing unicycle[edit]

Creating a self-powered unicycle that balances itself in three dimensions is a robotics and control theory problem. A self-balancing unicycle can be considered as a non-linear control system similar to that of a two-dimensional inverted pendulum with a unicycle cart at its base. There are many higher-order effects involved in modelling the full system. Rotation of the drive wheel itself can provide control in only one dimension, forwards and backwards. Control in other dimensions generally requires other actuators, such as auxiliary pendulums, reaction wheels, or control moment gyroscopes attached to the main unicycle pendulum.

Legal status[edit]

Laws in some places do not address powered unicycles, but there are some provisions regarding electric mobility devices for the disabled.[citation needed]

Human-ridable self-balancing unicycles and commercialization[edit]

Single-axis self-balancing ridable unicycles[edit]

Single-axis unicycles are self-balancing only in the forwards-backwards direction, so a rider must balance them from side to side, such as Trevor Blackwell's Eunicycle or the RYNO Motors Micro-Cycle.[better source needed][3] In 2008, Focus Designs released the first commercially available self-balancing unicycle.[better source needed][4] In 2011, Inventist marketed an 11 kg stand-up, seatless version called the Solowheel that has a weight, size and carry handles that make it usable by last mile commuters.[better source needed][5][6][7][8] Late in 2015, the Ford Motor Company patented a "self-propelled unicycle engagable with vehicle", intended for last-mile commuters.[9]

The RIOT wheel is a ridable single-axis self-balancing unicycle with an unusually low centre of gravity, with its rider in front of, rather than on top of its single wheel, balanced by a counterweight within the wheel.[citation needed]

True two-axis self-balancing ridable unicycles[edit]

A two-axis self-balancing unicycle balances itself side to side, in addition to the forward and backward axis.

  • In 2003, Bombardier announced a conceptual design for such a device used as a sport vehicle, the Embrio. It is unclear whether Bombardier ever intends to create a working prototype of this vehicle.[citation needed]
  • Aleksander Polutnik's Enicycle (2006) is probably the first two-axis balancing human-ridable unicycle.[citation needed]

Similar vehicles[edit]

A number of vehicles share characteristics of self-balancing unicycles:

Fictional self-balancing unicycles[edit]

OpenSource technology[edit]

The community developed some OpenSource technology for electric unicycles:

  • Android app
  • Shell to be 3D printed
  • Firmware

Please see more information on the EGG Electric Unicycle project page.

The community gathers on the online forum Electric Unicycle.

See also[edit]


  1. ^ Rice, Vincent (26 January 2012). "Version 2.0 of Focus Designs Self-Balancing Unicycle now ready for primetime". GizMag. Retrieved 25 September 2014. 
  2. ^ " :: Self balancing electric micro unicycle reviews :: Airwheel, Firewheel, Gotway, Inmotion, IPS, Legway, Ninebot One, Rockwheel, Solowheel :: All Reviews By Brand". Retrieved 2015-12-27. 
  3. ^ Micro-Cycle — archived RYNO Motors 'blog page
  4. ^ "Slide 3 Slide 3", Self-Balancing Unicycle | Focus Designs, Inc. | The SBU is the coolest light electric vehicle on the market. The gyro-stabilized SBU contains full-frontal nerdity!,, 2013-04-17, retrieved 2013-04-26 
  5. ^ "Home - SOLOWHEEL". 
  6. ^ Solowheel: self-balancing last mile transport for the upstanding commuter.
  7. ^ Last Mille Club, unicycle archive
  8. ^ Kaiman, Jonathan (May 30, 2015), "For Solowheel maker, a patent rights nightmare in China", The Los Angeles Times 
  9. ^ Read, Richard (December 29, 2015). "Ford Patent Could Transform Your Car Into A Unicycle". The Car Connection. Internet Brns Automotive Group. Retrieved 10 September 2016. 
  10. ^ Carnegie Mellon Press Release, August 6, 2006 – "Ballbot"
  11. ^ Ruan, Jian-Wei Zhao; Xiao-Gang (1 September 2011). "Modelling and Control of a Flexible Two-Wheeled Self-Balancing Mobile Robot". 3 (3): 330–355. doi:10.1504/IJSCC.2011.042438 – via ACM Digital Library. 
  12. ^ Flexible two-wheeled self-balancing mobile robot, 9th IFAC Symposium on Robot Control (2009)
  13. ^ Wu, Junfeng; Zhang, Wanying; Wang, Shengda (26 November 2012). "A Two-Wheeled Self-Balancing Robot with the Fuzzy PD Control Method". 2012: 1–13. doi:10.1155/2012/469491. 
  15. ^ "What is a Swegway?". 
  16. ^ ANALOG — Science Fiction/Science Fact, Vol. LXXXIII, No. 5, July 1969, pp. 120-151. Illustrations by Peter Skirka.
  17. ^ "Little Wheel - game at". Retrieved 2013-04-26. 

Further reading[edit]

  • S. V. Ulyanov et al. Soft computing for the intelligent robust control of a robotic unicycle with a new physical measure for mechanical controllability. Soft Computing Volume 2 Issue 2 (1998) pp 73–88.
  • Zenkov, DV, AM Bloch, and JE Marsden [2001] The Lyapunov-Malkin Theorem and Stabilization of the Unicycle with Rider. Systems and Control Letters, Volume 45, Number 4, 5 April 2002, pp. 293–302(10) (postscript format available here [1])
  • Zenkov, DV, AM Bloch, NE Leonard and JE Marsden, Matching and Stabilization of Low-dimensional Nonholonomic Systems. Proc. CDC, 39, (2000), 1289-1295. (pdf format available here [2])
  • Sheng, Zaiquan; Yamafuji, Kazuo: Realization of a Human Riding a Unicycle by a Robot. Proceedings of the 1995 IEEE International Conference on Robotics and Automation, Vol. 2 (c1995), pp 1319–1326
  • A. Schoonwinkel, "Design and test of a computer stabilized unicycle," Ph.D. dissertation, Stanford University, California, 1987.
  • Johnson, R.C. Unicycles and bifurcations, American J. of Physics, volume 66, no.7, 589-92

External links[edit]