TOKYO -- Recent advances in the development of artificial muscles by Japanese researchers may soon bring big benefits to such fields as nursing care, medicine, and search and rescue.
Artificial muscles are materials and devices that contract and expand in response to an electric, pneumatic or other stimulus and move in ways similar to their biological counterparts. Although they are slower and less powerful than motors, they can be made lighter and smaller, making it easier for them to make complex movements. When used in robots, artificial muscles add a degree of realism and subtlety of movement that results in an entirely new breed of machine capable of performing tasks not possible with motor-based technology.
A team from the Tokyo Institute of Technology, led by professor Koichi Suzumori, has developed a "muscle fiber" that consists of a rubber tube 1.2mm in diameter covered with a mesh made of a strong synthetic fiber. About 400 of these tubes are bundled together, and air is sent through each of the tubes to make them contract, reproducing the movements of the hamstrings and the muscles around the knee.
The team is also studying ways to expand artificial muscle fibers through a chemical reaction, rather than by using compressed air.
A delicate touch
Human leg muscles are comprised of bundles of large numbers of thin muscle fibers. The fibers in older-generation, pneumatically powered artificial muscles are thicker in diameter than the new type. The Tokyo institute's creation allows for a more nuanced movement because each fiber can be controlled separately. The researchers expect their technology to speed up the development of bipedal robots capable of walking smoothly even on uneven surfaces.
The team is focusing on using soft elastic materials for their creation because such attributes will make rescue robots more flexible, a trait that would make them better at navigating obstacles at disaster sites. The developers aim to commercialize the artificial muscle in three years. They also envision the muscle being used in the fingers of nursing care robots and in artificial arms and hands.
But their thinking goes even further outside the box. The team is considering incorporating artificial muscle fibers into clothing to create a kind of "power suit." The idea is that wearers would be able to perform physically demanding tasks with only minimal exertion.
At Nagoya University, associate professor Yukikazu Takeoka and other researchers have synthesized an artificial muscle material using a polymer gel. They devised an innovative way to produce the gel so that the material is 10 times more elastic than conventional polymer gel-based materials, such as the kind used in diapers.
One promising application for the new material is for use in helping medical devices deliver medicine to a specific part of the body. The gel moves the device by repeatedly expanding and contracting.
The greater fluidity of movement enabled by the latest crop of artificial muscles can offer benefits for nonhumanoid robots, too. Professor Ming Aiguo and other researchers at the University of Electro-Communications have created a robot that swims by mimicking the movements of a trout. The robot uses a fiber material that bends when electricity is applied. It can move forward and backward, as well as turn.
Potential uses include searching underwater for missing people in areas that have been hit by a tsunami. The researchers hope to commercialize the technology in 10 years.
All shapes and sizes
Research on artificial muscles has spiked worldwide in the past two or three years. Driving the trend is the growing use of robots in such fields as medical care, nursing care and disaster relief. Motor-driven robots are currently used for such purposes, but they cannot offer the same flexibility and delicacy of movement -- and, ultimately, safety -- as robots that employ "muscles."
The use of robots thus far has largely been limited to factories. For these machines, motors are ideal because they provide the kind of powerful, fast and precise movements needed for manufacturing. But off the factory floor, robots need to be light and capable of complex, delicate movements because their primary function shifts to serving people. This delicacy is difficult to achieve with motors alone.
Advances in artificial muscle research are literally reshaping robots, opening the door to the creation of snakelike devices that can slither through narrow openings and insectile machines that can climb walls on legs tipped with suction cups.
The research creates a virtuous circle: The more researchers learn how to mimic muscles, the better they understand the human body. The use of artificial muscles based on this deeper understanding will better equip doctors to treat diseases, patients to rehabilitate and athletes to improve.