Robotic unicycle

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The problem of creating a robotic unicycle, a self-powered unicycle that balances itself in three dimensions, is an interesting problem in robotics and control theory. Balancing such a vehicle is a similar control problem to balancing an inverted pendulum.

The theoretical work on the unicycle problem is complemented by work on the construction of actual mechanically ridden unicycles.

A number of vehicles are almost robotic unicycles:

The Segway is a vehicle which is capable of automatically balancing itself in the forwards-and-backwards direction, but has two parallel wheels rather than being capable of balancing from side to side.

The Eunicycle is a powered unicycle that is capable of balancing itself forwards and backwards automatically, but requires a human rider to balance it from side to side.

In 2003, Bombardier announced a conceptual design for such a device used as a sport vehicle, the EMBRIO. It is unclear whether Bombardier intends to create a working prototype of this vehicle.

Contents 1 Trivia 2 References 3 See also 4 External links

Trivia

• Pixar's 1987 animated film "Red's Dream" depicts a computer-animated unicycle riding itself. It is unclear to what degree this provided motivation for the research described above.

References

• 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 [1999] Stabilization of the Unicycle with Rider. Proc. CDC 38, 3470-3471 (pdf format available here)
• 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)
• 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.

See also

• Inverted pendulum
• Lyapunov-Malkin theorem
• Eunicycle - an example of a powered unicycle that self-balances front-and-back, but needs to be balanced by the rider side-to-side

External links

• Robot unicycle model (Japanese language text)
• http://www.ifr.mavt.ethz.ch/movic98/proceedings/78c.pdf another paper
• An interesting post from the Unicycling mailing list
• Mike Hinson's collection of unicyling, robotics, and physics links
• Bombardier Recreation Products EMBRIO one-wheeled recreational vehicle concept design
• The loonycycle, which superficially resembles a simple robotic unicycle, but uses side-thrusting fans for lateral balance
• Rosie the Robot - a Question of Balance Ken Perlin's page on robotic unicycles, with designs and java applet examples.
• Pixar - Red's Dream
• A robotic unicycle built for a university engineering project

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Note: the term "unicycle" is also sometimes used in robotics to mean a generalised cart or car moving in a two-dimensional world; these are also often called "unicyle-like" or "unicycle-type" vehicles. This usage is distinct from the sense of "one wheeled robot bicycle" above.

A physically realisable unicycle, in this sense, is a nonholonomic system. This is a system in which a return to the original internal (wheel) configuration does not guarantee return to the original system (unicycle) position. In other words, the system outcome is path-dependent.