Creative Robotics’ HUB-ee wheels are just what they sound like: hub wheels, where the motor is contained inside the wheel’s hub to save space on your robot. Hub wheels are great for complicated builds like rack-and-pinion steering rigs where you want wheels that both drive the robot as well as turn to steer. They also make for very clean builds because a lot of components you could normally see are hidden.
Each HUB-ee Wheel consists of a 12mm gearmotor, a small circuit board equipped with a motor driver chip and a quadrature encoder, as well a gearbox, all concealed inside the hub. They come in a small number of configurations: 180-1 and 120-1 gear ratios, available in either metric or imperial.
The wheels connect to a microcontroller with a Micro-MaTch ribbon cable, and Creative Robotics also offer breakout boards for managing these connectors, as well as a HUB-ee friendly prototyping shield. If you don’t want to use the breakout boards, Creative Robotics shows you how to cut a Micro-MaTch cable in half and attach the wires individually to the controller.
The HUB-ee wheels attach to your robot’s chassis one of two ways. The first are fairly typical M3 screws. The other is much more intriguing: the M3 holes also double as Lego cross-axle holes that accommodate a standard cross-connector pin. These holes don’t go all the way through, limiting the tensile strength of this attachment method. However, the cross-holes are on both sides of the wheels, allowing you add support to either side.