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Researcher Mickaël Achkar at the Swiss Federal Institute of Technology in Lausanne (EPFL) studied dogs’ biological mechanisms to create a smarter robot design.
“I wanted to engineer a robot with animal characteristics, bearing in mind that animals – like humans – move in a huge variety of ways,” he said. Most of these movements are executed by just a few joints, so he drew inspiration from animals’ motor control processes.
Dogs were an obvious choice thanks to a vast open-source dataset containing information on their motion. Achkar extracted data on their synergistic movements, which happen when several muscle groups are activated at the same time. This was summarised using a method known as principal component analysis, grouping the data into several vectors describing the main axes of dog motion. This information was then used to establish exact specifications for the robot.
The resulting robotic dog has bilateral symmetry. Each of its four legs has three joints, and each joint is coordinated with the others. This allows the robot to run in the same way as a real dog, the researchers claimed.
To build the prototype, Achkar used metal rods as the bones, 3D-printed pulleys as the joints and thin cables as the tendons.
During testing on a treadmill, researchers discovered that once the robot got moving, it could run autonomously without having to activate its control motors. “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 team then added a counterweight, similar to a pendulum, which restored the robot’s ability to stay in motion once it started by using resonance to inject energy.
The bot’s control motors are nevertheless useful for achieving a broader range of motion. It can jump and overcome obstacles without the help of its counterweight, for example. “We’d like to push our design further with the motors, but for now the prototype isn’t very robust,” said Achkar.
The mechanical dog was put to the test with obstacles, such as a stick placed between its legs. The robot was able to resume its gallop, the EPFL announcement said, reaching speeds of 6km/h.
“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.”
Achkar has submitted his research paper to a scientific journal for publication.
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