Artificial muscle makes soft robots stronger

A new type of artificial muscle allows soft robots to lift nearly 1,000 times their own weight.
By Jason Spencer | Nov 29, 2017
Scientists from Harvard University and MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) have created artificial muscles that allow soft robots to lift objects that are up to 1,000 times their own weight, a new study published in the Proceedings of the National Academy of Sciences reports.

Soft robotics has made large strides over the past decade. However, while recent advancements have enabled the machines to bend and flex in new ways, the softer materials typically come with reduced strength.

The new origami-inspired muscles in the study get around that obstacle and could one day lead to much more efficient machines.

"We were very surprised by how strong the actuators [aka, "muscles"] were," said study co-author Daniela Rus, the Andrew and Erna Viterbi Professor of Electrical Engineering and Computer Science at MIT, according to Phys.org. "We expected they'd have a higher maximum functional weight than ordinary soft robots, but we didn't expect a thousand-fold increase. It's like giving these robots superpowers."

Making muscle-like actuators is one of the largest challenges in engineering. Now that it has been overcome, scientists can potentially build nearly any robot for almost any task.

Each artificial muscle consists of an inner "skeleton" made from materials like metal coil or a sheet of folded plastic surrounded by air or fluid and sealed inside a plastic or textile bag. A vacuum inside the bag causes the muscles to move by forcing the "skin" to collapse onto the skeleton. That tension drives the motion, and allows the device to work without any other external human input.

In the study, the team created dozens of different muscles with materials ranging from metal springs to packing foam to sheets of plastic. They then experimented with different skeleton shapes to create muscles that can contract down to 10 percent of their original size, lift a flower off the ground, and twist into a coil.

Those experiments showed the muscles can move in many ways, and are able to operate with a high amount of resilience. Not only that, but the technology can generate roughly six times more force per unit area than mammalian skeletal muscle, and is both lightweight and easy to make. A single muscle can be constructed within ten minutes using materials that cost less than $1.

Another important property is that the actuators are highly scalable, meaning they can be constructed at different sizes. That is important because it greatly increases their potential applications. The team believes they could one day be used for a wide variety of tasks, includingminiature surgical devices, wearable robotic exoskeletons, transformable architecture, deep-sea manipulators, and large deployable structures for space exploration.

"The possibilities really are limitless," added Rus, in a statement. "But the very next thing I would like to build with these muscles is an elephant robot with a trunk that can manipulate the world in ways that are as flexible and powerful as you see in real elephants."

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