(Controlling the pose of a double pendulum with a single motor between the rods, at arbitrary pose, and with arbitrary rod dimensions.)
VTOL using balance
a) stable, (CG between the wheels), b) will be falling backwards (CG behind rear wheel), c), d), e) examples of poses
Experiment from 2010 with an AVR processor. Unfortunately fixed point arithmetic made it really tiresome to work with.
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.