ROBOTS MUSCLE UP: "Not only can the artificial muscles move in many ways, they do so with impressive resilience. They can generate about six times more force per unit area than mammalian skeletal muscle can....".

Author:Brownell, Lindsay

SOFT ROBOTICS has made leaps and bounds over the last decade, as researchers around the world have experimented with different materials and designs to allow once rigid, jerky machines to bend and flex in ways that mimic and can interact more naturally with living organisms. However, increased flexibility and dexterity has a tradeoff of reduced strength, as softer materials generally are not as strong or resilient as inflexible ones, which limits their use.

However, researchers at the Harvard's John A. Paulson School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering, as well as the Massachusetts Institute of Technology's Computer Science and Artificial Intelligence Laboratory (CSAIL) have created origami-inspired artificial muscles that add strength to soft robots, allowing them to lift objects that are up to 1,000 times their own weight using only air or water pressure.

"We were very surprised by how strong the actuators [aka muscles] were," says Daniela Rus, professor of electrical engineering at MIT. "We expected they'd have a higher maximum functional weight than ordinary soft robots, but we didn't expect a 1,000-fold increase. It's like giving these robots superpowers."

"Artificial muscle-like actuators are one of the most-important grand challenges in all of engineering," notes Robert J. Wood, professor of engineering and applied sciences at SEAS and Founding Core Faculty member at Wyss. "Now that we have created actuators with properties similar to natural muscle, we can imagine building almost any robot for almost any task."

Each artificial muscle consists of an inner skeleton that can be made of various materials, such as a metal coil or a sheet of plastic folded into a certain pattern, surrounded by air or fluid and 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 is determined entirely by the shape and composition of the skeleton.

"One of the key aspects of these muscles is that they're programmable, in the sense that designing how the skeleton folds defines how the whole structure moves. You essentially get that motion for free, without the need for a control system," explains Shuguang Li, postdoctoral fellow at...

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