I found this self-balancing unicycle via Trevor Blackwell’s site. Dr. Hofer’s self-balancing unicycle uses a wide tire for lateral stability. Trevor had spent several months learning how to ride a unicycle before building his; the large tire makes the learning curve for this one a lot less severe. The project site is in German, but I found one write-up in English. The majority of it is dedicated to the control scheme. It is very difficult to model the unicycle as an inverse pendulum due to so many unknowns. Dr. Hofer’s team used fuzzy control instead which let them apply several layers of rules without requiring a lot of previous knowledge. Here’s a photo gallery of the device.
[sean] reminded me that I forgot to include the obligatory link to Bombardier’s Embrio concept.