Robotic dog runs independently on a treadmill with no support

Engineers from the Computational Robot Design & Fabrication Lab (CREATE) at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland built and designed this robotic dog prototype. 

How was the robot built? 

The team conceptualized this robot based on real dogs’ motor control processes. They investigated the biological mechanisms of actual dogs to imitate them in a robotic creation. 

This resulted in the development of a prototype that can operate on its own once put in motion without the support of motors.

Three joints connect the robot's four legs; all synched with one another. This ability enables the robot to move swiftly, much like a real dog. 

Core robotic parts are built around metal rods that function as bones, 3D-printed pulleys that serve as joints, and thin wires that act as tendons. All the parts are held together with the help of a few screws.

This robotic dog has bilateral symmetry, which signifies any organism or object that can be divided into two equal halves.

A dog was chosen above any other animal, like a cheetah, since a wealth of datasets on the movements of dogs was accessible in open source. 

The data was then methodically organized using the "principal component analysis" approach in the next phase. “This [component analysis] basically entailed grouping the data into several vectors describing the main axes of dog motion and using this information to establish exact specifications for the robot,” explained the release. 

The testing on a treadmill

The team tested their prototype’s motion using a treadmill.

To their surprise, once the robot was put into action, it could operate independently without the activation of control motors. Simply put, the treadmill's motion was enough to keep it going. Moreover, it quickly achieved a 6 km/h speed on the treadmill.

In another test, scientists placed a stick between its legs, and the robot continued its graceful gallop without any damage.

A counterweight, similar to a pendulum, was affixed to the robot's body to enable it to stay in motion. “The counterweight uses resonance to inject energy,” said Mickaël Achkar, who led this development.  

However, the robot’s control motors could still be used to achieve a broader range of motion, for instance, jumping and overcoming any terrain obstacles without the help of its counterweight. 

“We’d like to push our design further with the motors, but for now, the prototype isn’t very robust. Our goal isn’t to compete with ultra-high-tech robotic dogs, but rather to explore bio-inspired robot designs,” said Achkar.

“This entails honing a robot’s fundamental design and modifying its passive proprieties so that only simple control systems are needed – all while maximizing the robot's capabilities. What we’ve done here – engineering the joints to work in synergy – has already proven useful for creating robotic hands and other body parts,” concluded Achkar.

The team has yet to indicate which domains this new robot may be employed in in the future.

The study report for this prototype has been submitted to a scientific journal for publication.