Artificial Muscles Give Soft Robots ‘Superpowers’

Researchers have created origami-inspired artificial muscles that allow soft robots to lift objects up to 1,000 times their own weight. The artificial muscles can be made for less than $1.

While soft robots can bend and flex in ways similar to living organisms, they lack the strength of a typical rigid robot, which limits their use. Until now.

Researchers at the Wyss Institute at Harvard University and MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) have created origami-inspired artificial muscles that allow soft robots to lift objects that are up to 1,000 times their own weight using only air or water pressure.

For comparisons sake, a UR10 robot arm that weighs 64 pounds can lift a third of its weight.

According to the researchers, the artificial muscles consist of an inner skeleton that can be made of various materials and is surrounded by air or fluid. The muscles are also sealed inside a plastic or textile bag that serves as the skin. A vacuum applied to the inside of the bag initiates the muscle’s movement by causing the skin to collapse onto the skeleton, creating tension that drives the motion. No other power source or human input is required to direct the muscle’s movement. It’s simply determined by the shape and composition of the skeleton.

MIT CSAIL director Daniela Rus says these artificial muscles are “giving these robots superpowers.”

This video shows how origami-inspired artificial muscles can be customized into nearly any shape and lift up to 1,000 times their own weight. Credit: Wyss Institute at Harvard University

“When creating robots, one always has to ask, ‘Where is the intelligence – is it in the body, or in the brain?’” adds Rus. “Incorporating intelligence into the body (via specific folding patterns, in the case of our actuators) has the potential to simplify the algorithms needed to direct the robot to achieve its goal. All these actuators have the same simple on/off switch, which their bodies then translate into a broad range of motions.”

The artificial muscles can also move with impressive resilience. They generate about six times more force per unit area than mammalian skeletal muscle can, according to the researchers. And they’re also quick and cheap to produce; a single muscle can be built in ten minutes for less than $1.

“Artificial muscle-like actuators are one of the most important grand challenges in all of engineering,” says Rob Wood, Ph.D., corresponding author of the paper and Founding Core Faculty member of the Wyss Institute, who is also the Charles River Professor of Engineering and Applied Sciences at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS). “Now that we have created actuators with properties similar to natural muscle, we can imagine building almost any robot for almost any task.”

The structural geometry of artificial muscle skeleton determines the muscle’s motion. Credit: Shuguang Li / Wyss Institute at Harvard University

The artificial muscles are powered by a vacuum, a feature that makes them safer than most of the other artificial muscles currently being tested. The researchers envision the artificial muscles being used in numerous applications at multiple scales, such as miniature surgical devices, wearable robotic exoskeletons, transformable architecture, deep-sea manipulators for research or construction, and large deployable structures for space exploration.

“In addition to their muscle-like properties, these soft actuators are highly scalable. We have built them at sizes ranging from a few millimeters up to a meter, and their performance holds up across the board,” Wood says.

The team was even able to construct the muscles out of the water-soluble polymer PVA, which opens the possibility of robots that can perform tasks in natural settings with minimal environmental impact, as well as ingestible robots.

“The possibilities really are limitless. 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,” Rus says.

The study will be published this week in Proceedings of the National Academy of Sciences (PNAS).

About the Author

Steve Crowe · Steve Crowe is managing editor of Robotics Trends. Steve has been writing about technology since 2008. He lives in Belchertown, MA with his wife and daughter.
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