Cubli

The video shows a research project at ETH Zurich called Cubli. It takes advantage of reaction wheels, in several unique ways. Typically a reaction wheel is used on an orbiting space craft in order to maintain attitude. Basically they are a type of flywheel that is continuously spinning. A change in angular speed/momentum of the reaction wheel results in an adjustment of the craft, due to the conservation of angular momentum.

Cubli takes this to the next level. Spacecraft are typically outside the effects of a large gravitational pull, and angular corrections are calculated only in the inertial frame of the craft. Cubli is working within another inertial reference frame, so all of its attitude adjustments must take into account that frame, that is gravity. Watching the video you can see the reaction wheels spin up and then quickly brake in order to bring the cube first up on edge, then on its vertex. The positioning of the cube is maintained using the reaction wheels, and the reaction wheels can also be used to control the direction of the fall, creating a "Walking" action.

There are more videos after the break, as well as a couple other pretty awesome projects at the Institute for Dynamic Systems and Control at ETH Zurich.