Scientists Create Robotic Leg with Artificial Muscles

Scientists from ETH Zurich and the Max Planck Institute for Intelligent Systems have created a robotic leg that runs on artificial muscles, demonstrating agility and energy efficiency in navigating varied terrains.

The research is published in the journal Nature Communications.

The robotic leg uses artificial electro-hydraulic muscles to power its movements, differing from traditional robots that typically employ motors. The artificial muscles are oil-filled plastic bags with conductive black electrodes on the sides. When an electric charge is applied, the electrodes attract each other, pushing the oil to one side and shortening the bag. This mechanism, which mimics the contraction and extension of muscles in living creatures, enables the leg to move in various directions.

"When we activate these muscles, the so-called electro hydraulic actuator slips together, which means the electrodes come closer and push the oil to the other side of the actuator. This leads to a contraction and thickening of the muscle, similar to a human muscle," Thomas Buchner, Doctoral Researcher in the Soft Robotics Lab at ETH Zurich said.

A key feature of the leg's design is the antagonistic pairing of these muscles at each joint, akin to the interaction between human biceps and triceps.

"If the biceps contract, the triceps stretches, and the other way around the biceps stretches when the triceps contracts," Buchner explained.

Unlike motor-driven robots, these electro-hydraulic actuators are more energy-efficient, capable of high jumps, quick movements, and automatic adjustment to uneven terrains without complex sensors.

The leg's agility comes from its ability to explosively lift its own weight, similar to a human jumping. Moreover, it can adapt to the environment without needing sensors to constantly monitor its angle.

The team is now focusing on further developing these adaptive artificial muscle systems that encompass elements like tendons and bio-inspired joints.