The Institute for Dynamic Systems and Control, a research institute at ETH Zurich university, has developed Cubli*: a 15 × 15 × 15 cm cube that can jump up and balance on its corner.
Reaction wheels mounted on three faces of the cube rotate at high angular velocities and then brake suddenly, causing the Cubli to jump up.
Once the Cubli is balancing on its edge, the next two wheels are instantaneously stopped to make it stand on its corner, and an inertial measurement unit (IMU) allows the motor torques to be precisely controlled to make the Cubli continue standing.
In addition to balancing, the motor torques can also be used to achieve a controlled fall such that the Cubli can be commanded to fall in any arbitrary direction.
Combining these three abilities — jumping up, balancing, and controlled falling — the Cubli is able to “walk.”
Technical details in open-access papers cited below.
* Cube + the Swiss German diminutive for “cube”