Perhaps the most basic type of mobile robotic chassis involves a pair of motors that drive and turn it like a tank, with some sort of supporting “pivot point” to keep it upright. While this pivot is normally a single ball bearing or just a post that gets dragged along, this build by Markus Purtz puts a different spin on things, adding an actual steerable third wheel.
The result is something entirely unique, with two wheels pulling the vehicle, while a single wheel in the back acts almost like a boat’s rudder, guiding it in the proper direction. This back wheel is steered by a small MG90S servo, via rods attached to the horn. The result, as seen in the video below, is a very speedy and maneuverable vehicle. Although only the back wheel is used for steering, with an ESC hooked up to each driving motor, it should even be possible to use a combination of differential and turning control for even more control options.
In addition to the interesting motor setup, this 3D-printed device features a series of magnets to keep the top cover on. It also has accommodations for both an FPV RC camera, and a GoPro if you want to film its exploits. Print files are available on Thingiverse if you’d like to make your own.