Flexible ‘Tissue’ Gives New Muscle to Robots

Nothing fires the imagination like advances in the field of robotics. And the latest — soft muscle “tissue,” that solves a huge problem for the next phase of life-like robotics, promises to bring the Terminator that much closer to reality. That’s because replicating the fluid motion of humans has always eluded engineers and scientists — relegating any talk of human-like robots to the realm of science fiction and movies. But engineers now say they have a solution to their vexing problem.

The newly developed synthetic muscle is based closely on natural muscle movements — inspired by muscles in living organisms — and is made from silicone rubber interspersed with tiny bubbles of ethanol, which give it low density and high elasticity. When ethanol is heated, it greatly expands within the rubber, causing a rapid “tremendous increase in volume,” the research reports. To do any lifting, previous models employed bulky pneumatic or hydraulic systems.

The rubber material of the new and improved version, according to New York’s Columbia University engineers, can be 3-D-printed into as many shapes as can be imagined, and electrically actuated through a thin wire embedded inside the “muscle.” When prompted through heat generation, the material can expand to nine times its original size.

In tests, the flexible rubber muscle demonstrated incredible strength, having a strain density – the amount of energy stored in each gram of a stretched elastic body – 15 times greater than human muscle. Moreover, the material was able to lift 1,000 times its own weight, said researchers who reported their work in the journal Nature Communications.

Professor Hod Lipson, from the Creative Machines laboratory at Columbia, said in a report on the lab’s website: “We’ve been making great strides toward making robot minds, but robot bodies are still primitive. This is a big piece of the puzzle and, like biology, the new actuator can be shaped and reshaped a thousand ways. We’ve overcome one of the final barriers to making lifelike robots.”

Overcoming the clunkiness of robotic movement has long been the goal of engineers. Though advances in thinking and computing have been well established, fluid movements have evaded researchers due their reliance on hydraulics. The flexible rubber “muscles” promise to overcome that. Robots with the new “tissue” can grasp and manipulate much like humans, and will be better able to perform delicate tasks such as surgery, and pick up soft objects, Lipson’s research shows.

Dr. Aslan Miriyev, who co-authored the research, said: “Our soft functional material may serve as robust soft muscle, possibly revolutionizing the way that soft robotic solutions are engineered today. It can push, pull, bend, twist, and lift weight. It’s the closest artificial material equivalent we have to a natural muscle.”

So while it may be some time yet before robots replace humans in the workforce, at least this much is clear: The path to get there has just cleared one of the few remaining hurdles. The next step — many say the final step in the evolution of artificial intelligence — will be programming a robot’s “mind” to control the muscles.