James Bruton Builds Tank Vehicle Inspired by Conveyor Belts

Go take a look at a modern conveyor system. In many cases, it won't actually use a belt at all. Instead, it will use a track made up of hundreds of segments linked together. Unlike a belt that can really only flex along its length so it can loop back around on itself, a segmented track has some flexibility in the horizontal plane. That allows the track to make turns, which is pretty important in a modern factory. James Bruton found that inspiring and used the idea to make this tank vehicle that steers by bending.

Bruton has built many tracked vehicles over the years and most of them steer like a conventional tank: by adjusting the relative speeds — or even directions — of the tracks. If the left track moves forward faster than the right track, then the vehicle will make a gradual right turn. If the left track moves forward at the same speed as the right track moves backward, the vehicle will spin clockwise in place.

But this vehicle is much different. It only has a single track, so there is no way to use vectoring like that for steering. Inside, this vehicle steers by physically altering the shape of the track into an arc. That's possible because the tank track is very similar to what you'd see on a conveyor. Bruton designed the track segments so that they have a little bit of play, which lets them sit at an angle relative to each. Each pair of segments only allows a small angle, but that adds up quickly and results in a substantial arc across the length of the vehicle.

The vehicle's structure and the track are all 3D-printed. The track wraps around two drive units, each of which contains a motor controlled by an Arduino Mega 2560. Those motors rotate cogs that drive the track. A heavy duty pivot joint connects the two drive units and only allows them to move relative to each other along the same horizontal plane. A linear actuator arm controls the angle of the joint and ultimately the radius of the track's arc. A small arc results in a tight turn, while a large arcs results in a wide turn.

But even at the tightest, the turning radius of this vehicle is quite large — it won't be turning on a dime by any means. The vehicle also isn't very good at climbing over obstacles, though Bruton thinks that he could improve that ability with some design revisions. As is, this single-track bending tank is a cool example of an unusual and innovative drive type.