James Bruton’s Amazing 3D-Printed Robot Dog Can Now Walk Dynamically

4/16/20Update:

James Bruton has done a pretty significant redesign of the openDog since his last video. Most important among the changes is the reversal of the front legs, so that the knees bed in the same direction as the front legs. Be sure to check out his newest video to get a look at the new design.

The world has been stunned again and again with robots like Boston Dynamics’ Spot and Atlas — a quadruped robot dog and biped robot humanoid respectively. Each of those robots was the result of several years of research and development, and millions of dollars in funding. They were designed and built by large teams of engineers, each of whom is specialized in a specific area of robotics. That would lead you to believe that it isn’t possible for a single person working alone to create something similar. But James Bruton is dispelling that myth by assembling a mini prototype of a robot dog called openDog, dubbed "miniDog," which it is now able to walk dynamically.

When we say that a robot can is capable of “dynamic walking,” we mean that it is able to adjust its gait as necessary to react to unpredictable external forces. It’s straightforward enough to program a quadruped robot to put one foot in front of the other as it traverses a nice, flat surface. But it’s quite another to implement the programming — and necessary sensors — that allow it to handle unforeseen circumstances. Boston Dynamics is at the forefront of that capability, and they have demonstrated their robots’ ability to react instantaneously to respond to tripping, being shoved, and more. Bruton has given his miniDog the same capability, but on a much more humble budget.

The vast majority of miniDog's mechanical and structural components were 3D-printed, which is an achievement in its own right. It is actuated by numerous motors and servos to give each leg several degrees of freedom. Most importantly, however, is the feedback system. Bruton has implemented that in the most affordable way possible, with a combination of an IMU (Inertial Measurement Unit) sensor and a handful of Hall effect sensors. The IMU tells the robot if it’s leaning too far in any one direction. The Hall effect sensors are attached to the legs, and tell the robot how much the legs are flexing under stress. Bruton utilized a similar approach in his Sonic the Hedgehog robot to help it respond to bumps as it drives around. These sensors, together with clever programming, let openDog continue to walk reliably — even when substantial external forces are applied to it.

Bruton still has a lot of work to do on openDog, so be sure to subscribe to his YouTube channel to follow the progress on this project.