This is the One-Wheel Cubli: an inverted pendulum system that can balance on its pivot using a single reaction wheel. It has 2 degrees of freedom. As the inertia in one direction is higher than the other, the system moves faster in the direction with the lower inertia.
This robot has inertial sensors that measure tilt angles and angular velocity. A microcontroller interprets the data to send commands to the motor.
[HT] [Researchers: Matthias Hofer, Michael Muehlebach, Raffaello D’Andrea || Design: Michael Egli, Matthias Müller]