a) stable, (CG between the wheels), b) will be falling backwards (CG behind rear wheel), c), d), e) examples of poses
Experiment from 2010, Currently on hold. The program relies on solving differential equations, which are a bit heavy (and difficult to debug) for traditional embedded processors. (A processor with an fpu (math co-processor) should have been used.)
One use of the system could be for VTOL (Vertical Take Off and Landing) in cases where the wheels can't roll on the ground like for example a small remote controlled airplane landing on some unprepared ground.
However if the wheels can roll on the ground, there would be a more stable and simpler solution where the wheels also are equipped with a motor similar to the Segway.