Reaction-Wheel Cube

A cube designed to hold itself upright on a single edge using reaction wheels. The principle is momentum exchange: accelerate a flywheel one direction and the frame is pushed the other, and if you can do that fast enough and precisely enough, you can catch the cube faster than gravity can tip it over.

The frame is machined aluminum rather than printed, because the wheels need something stiff to react against — any flex in the structure shows up as lost control authority. The wheels themselves were machined and balanced, and the drive and sensing are handled on an Arduino with an IMU closing the loop.

Most of the work has been mechanical: getting the frame square, the wheels concentric, and the mass where the model says it should be.