Here is a neat unicycle robot that can jump on one of its wheel and balance using brushless motors. It stands 22cm tall and has two identical wheels for balancing. It has 3D printed components. The robot uses optical encoders to record rotational velocity for the motor while 4 IMUs are used to sense the Wheelbot’s orientation in space.
The Wheelbot relies on 4 x batteries (24V) to move. As you can see in the above video, this robot can maintain its balance when pushed or put on a tilted surface.