Researchers at ETH Zurich are very good at keeping robots upright. In 2022, the school’s robotics team taught the quadruped ANYmal robot how to climb a mountain without falling over. The school’s new research, published in collaboration with the Max Planck Institute for Intelligent Systems in Stuttgart, takes a unique approach to the problem of traversing uneven terrain.
The artificial muscles shown at the school are powered by a hybrid electro-hydraulic system. In addition to the ability to automatically adapt to the surface on which they are moving, the legs move faster and jump higher than their more standard electric counterparts, and they do not require additional sensors or control devices.
The actuator on the bridge is surprisingly simple. The team describes it as “a plastic bag filled with oil, similar to those used to make ice sculptures.” The bag is then covered with electrodes. To be honest, the whole thing feels a bit like a school science project.
“As soon as you apply voltage (to the electrodes), the electrodes are attracted to each other because of the static electricity,” said graduate student Thomas Buchner. “Similarly, if you rub a balloon against your head, the same static electricity causes your hair to stick to the balloon.”
The bag then expands or contracts depending on the voltage applied. Unlike standard electric actuators, this system does not generate much heat.
So the actuators help the system traverse uneven terrain and jump high. But in terms of practical use, the system still has a long way to go.
“Compared to walking robots using electric motors, our system is still limited: the legs are currently attached to bars and can only move in circles and jump, not yet freely,” says Christoph Keplinger, a professor at the Max Planck Institute for Robotics. “By combining the robotic legs with quadruped robots or bipedal humanoid robots, they could one day be deployed as battery-powered rescue robots.”
