This 3D-Printed AT-AT Is Big Enough to Ride On

Do you remember the first time you watched The Empire Strikes Back? There was a lot to admire in that movie, but few things inspired as much respect for the Empire’s might as the AT-ATs walking across the frozen surface of Hoth. The sheer scale of those machines was breathtaking and James Bruton was able to capture some of that greatness by 3D printing an AT-AT that is big enough to ride on.

A year ago, Bruton made an AT-AT robot on a much smaller scale—though it was still quite large, at about the size of a beagle. But that pales in comparison to this build, which is truly gargantuan. It is close to the size of an Asian elephant and is strong enough to carry a full-grown man. That would be cool under any circumstances, but it is especially impressive because this AT-AT doesn’t have hydraulics or a welded-steel frame. Bruton constructed it using aluminum extrusion and 3D-printed parts, and actuated everything using electric motors.

Bruton made a video a couple of months ago that went into detail about the design of the legs. Each leg is a connected pair of parallelograms, actuated by electric motors via unique 3D-printed gearsets integrated into the structure of the leg. Not only do those let Bruton move the legs with relatively small DC gearmotors, but they also make the legs look like those of the AT-ATs we saw on screen. Each leg has its own Teensy 4.0 development board to control its two motors and Bruton added potentiometers for feedback, so the motors can act like servos.

The movies don’t really show us how the AT-ATs turn — from what we can see, they really shouldn’t even be able to do so. That meant that Bruton had to come up with a way to make his AT-AT turn that would look right. He chose to make the legs pivot along the horizontal plane on oversized lazy Susan turntables, actuated by more motors.

The AT-AT is pilotable via a handheld controller, which has a Teensy 4.1 development board inside. It communicates with the other Teensy boards through RJ45 (Ethernet) cables.

Finally, Bruton turned to Billie Achilleos for help with dressing up the massive robot. She used lots of EVA foam and paint to create panels that cover the legs, as well as a big head. With those, the machine is instantly recognizable as an AT-AT.