At Nagasaki University in Nagasaki-City, Japan, mechanical engineer Shunji Moromugi straps on a pair of what he calls "power pants" and gets to work. Holding a 16-kilogram barbell on his shoulders, he does 90 squats in 90 seconds without breaking a sweat. That's because the pants contain computerized sensors that detect what his legs are doing-deep knee bends-and tubelike artificial muscles, mounted on both sides of the knee, that expand and contract with flows of compressed air. The artificial muscles are attached to a steel brace that spans the thigh and calf; when they lengthen, they extend Moromugi's knee and help him stand more easily.

These power pants might just be the closest thing yet to a realization of long-held visions of mechanical systems that improve the mobility of the elderly and disabled or boost the strength of soldiers and rescue workers. Where previous wearable robots proved cumbersome and hard to control, this latest version-a collaboration between Nagasaki University, the University of Electro-Communications in Tokyo, Japan, and the University of California, Irvine-is smarter and more practical. Robotics experts say it's an important step toward building machines that people will actually use. "This is novel because it's sensing over the entire soft-tissue interface of the body," says Ephrahim Garcia, a mechanical and aerospace engineer at Cornell University and a former program manager at the U.S. Defense Advanced Research Projects Agency. "You need intense amounts of computation to pull it off," he adds.