After seeing full-sized vehicles where a human — or even two — sits in between gigantic rolling wheels, Leon van den Beukel decided to make a miniature version operated over Bluetooth. His device’s wheels certainly won’t support a person, but stand several inches tall, large enough to accommodate a trio of bearings and a gearmotor in each, and push the limits of his printer’s bed area.
The wheels can spin together or differentially, allowing the rig to move and turn under control of a simple Android Bluetooth app. A breadboard in the center of the roller body is held somewhat upright by the weight of batteries underneath, though it’s definitely prone to rolling around unpredictably. A slice of bicycle tubing is attached to a 3D-printed wheel that mounts to each gearmotor, which contacts its larger wheel via slices of sandpaper.
Control is accomplished through an HC-05 Bluetooth module, along with an Arduino Pro Mini board. Everything is wired through a small breadboard at the center of the device, and an L298N H-bridge board provides power to the motors. Be sure to check it out rolling along the floor in the video below, and if you want to make something similar, Arduino code, STLs, and the Android control app are available on GitHub.