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A shout-out to those who think that Cubli is a gyroscope. It is not. In a gyroscope the wheel spins at a high angular velocity to keep constant orientation. In the Cubli we use reaction torques to balance. These torques are what the Cubli's structure 'feels' when the three motors attached to it accelerate or decelerate the wheels. In fact, Cubli's controller tries to minimize wheel velocities in addition to keeping the structure upright. This method is more reactive to external disturbances and reduces vibrations and sensor noise.

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(original comment modified for simplicity, Thanks +Markus Waibel)