While we've seen a number of quadruped "robotic dogs" lately, they all require control motors to maintain their running gait. An experimental new one, however, keeps running on its own once it's been set in motion.
The device was created by Canadian robotics student Mickaël Achkar at Switzerland's EPFL research institute, based on existing motion-capture data of actual running dogs. Utilizing a technique known as principal component analysis, the data was grouped into multiple vectors describing the main axes of dog motion, which in turn guided the design.
The resulting bilaterally symmetric robot has metal rods for bones, 3D-printed polymer pulleys for joints, and thin steel cables for tendons. And as is the case with a real dog, each of its four legs has three joints, each one of which is mechanically coordinated with the others.
When Achkar and colleagues tried testing the robot on a motorized treadmill, they were surprised to discover that once the bot had started running, the motion of the treadmill was all that was required to keep it doing so. Although the robot had been equipped with motors that could be used to move each leg, these didn't have to stay activated.
"At first we thought it might’ve been a fluke," said Achkar. "So we changed the design slightly and tested the robot again – and it couldn’t run anymore."
The scientists proceeded to add a pendulum-like counterweight to the back of the robot, to help keep it in motion once it had started running. That said, the bot obviously isn't a perpetual motion machine, and still utilizes its motors for motions such as jumping and stepping over obstacles.
"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."
You can see the robot in dog-like running action, in the following video.
Source: EPFL