The prospect of slipping into a robotic exoskeleton that could enhance strength, keep the body active while recovering from an injury or even serve as a prosthetic limb has great appeal. Unlike the svelt body armor donned by Iron Man, however, most exoskeletons to date have looked more like clunky spare parts cobbled together.

Japan's CYBERDYNE, Inc. is hoping to change that with a sleek, white exoskeleton now in the works that it says can augment the body's own strength or do the work of ailing (or missing) limbs. The company is confident enough in its new technology to have started construction on a new lab expected to mass-produce up to 500 robotic power suits (think Star Wars storm trooper without the helmet) annually, beginning in October, according to Japan's Kyodo News Web site.

CYBERDYNE was launched in June 2004 to commercialize the cybernetic work of a group of researchers headed by Yoshiyuki Sankai a professor of system and information engineering at Japan's University of Tsukuba. Its newest product: the Robot Suit Hybrid Assistive Limb (HAL) exoskeleton, which the company created to help train doctors and physical therapists, assist disabled people, allow laborers to carry heavier loads, and aid in emergency rescues. A prototype of the exoskeleton suit is designed for the small in stature, standing five feet, three inches (1.6 meters) tall. The suit weighs 50.7 pounds (23 kilograms) and is powered by a 100-volt AC battery (that lasts up to five hours, depending upon how much energy the suit exerts). By way of comparison, a lower-body exoskeleton developed by the Massachusetts Institute of Technology Media Lab's Biomechatronics Group is powered by a 48-volt battery pack and weighs about 26 pounds (11.8 kilograms).

CYBERDYNE (which film buffs will recognize as the name of the company that built the ill-fated "Skynet" in the Terminator movies) designed the HAL exoskeleton primarily to enhance the wearer's existing physical capabilities 10-fold. The exoskeleton detects—via a sensor attached to the wearer's skin—brain signals sent to muscles to get them moving. The exoskeleton's computer analyzes these signals to determine how it must move (and with how much force) to assist the wearer. The company claims on its Web site that the device can also operate autonomously (based on data stored in its computer), which is key when used by people suffering spinal cord injuries or physical disabilities resulting from strokes or other disorders.

The HAL exoskeleton is currently only available in Japan, but the company says it has plans to eventually offer it in the European Union as well. The company will rent (no option to buy at this time) the suits for about $1,300 per month (including maintenance and upgrades), according to the company's site, which also says that rental fees will vary: Health care facilities and other businesses renting the suits will pay about three times as much as individuals. The site does not explain why, and the company could not be reached for comment.

CYBERDYNE is not the only company developing exoskeleton technology. The U.S. Army is in the very early stages of testing an aluminum exoskeleton created by Sarcos, a Salt Lake City robotics and medical device manufacturer (and a division of defense contractor Raytheon), to improve soldiers' strength and endurance. The exoskeleton is made of a combination of sensors, actuators and controllers, and can help the wearer lift 200 pounds several hundred times without tiring, the company said Wednesday in a press release. The company also claims the suit is agile enough to play soccer and climb stairs and ramps.

But there are still many kinks that must be worked out before HAL or any other exoskeleton become part of everyday life. Exoskeletons work in parallel with human muscles, serving as an artificial system that helps the body overcome inertia and gravity, says Hugh Herr, principal investigator for M.I.T.'s Biomechatronics Group, which is developing a light, low-power exoskeleton that straps to a person's waist, legs and feet. Wearers' feet go into boots attached to a series of metal tubes that run up a leg to a backpack. The device transfers the backpack's payload from the back of the wearer to the ground.

One of the difficulties in developing exoskeletons for health care is the diversity of medical needs they must meet. "One might have knee and ankle problems, others might have elbow problems," Herr says. "How in the world do you build a wearable robot that accommodates a lot of people?"

There are also concerns about the exoskeleton discouraging rehabilitation by doing all of the work of damaged limbs that might benefit from even limited use. "If the orthotic does everything," Herr says, "the muscle degrades, so you want the orthotic to do just the right amount of work."

Power efficiency could also become an issue, given that the HAL moves thanks to a number of electric motors placed throughout the exoskeleton. The problem with electrical power is that you have to recharge, says Ray Baughman, professor of chemistry and director of the University of Texas at Dallas's NanoTech Institute. Baughman and his colleagues have been developing substances that serve as artificial muscles (by converting chemical energy into electrical energy) that may someday be able to move prosthetic limbs and robot parts. Their goal is to avoid the downtime inherent in motor-powered prosthetics that must be recharged.

Makes you appreciate Iron Man's strength and agility all the more.