Coming soon: A real superhero suit

Published May 9, 2008

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Iron Man, the latest offering from Marvel Studios, opened countrywide last weekend weekend. The movie is about a genius businessman who invents a suit of armour with extraordinary strength. Like all comic book heroes, Iron Man isn't real, right?

In 1963, when Iron Man first appeared in comic books, US Army researcher Serge Zaroodny published a report describing his design for a wearable robot that would provide the wearer with superhero power.

It wasn't until nearly 40 years later that the Pentagon's Defence Advanced Research Projects Agency (Darpa) launched a $75-million programme called Exoskeletons for Human Performance Augmentation, to design a machine that would allow soldiers to carry heavy weights, hike for days without tiring, whisk injured soldiers off the battlefield, handle large weapons, and even include armour that would protect it from enemy fire.

A number of exoskeletons went into development thanks to funding from Darpa, among them the Sarcos XOS, developed by Steve Jacobsen.

The XOS is a robotic exoskeleton, which the user steps into and straps on like a robot suit. Sensors in the hand-grips, feet and back detect the movements of the operator's body and send the data to a central processor hundreds, sometimes thousands of times a second.

The computer then calculates how to move the exoskeleton to minimise the strain on the operator. It then sends instructions to a series of valves that control the flow of high-pressure hydraulic fluid to cylinder actuators in the joints. The fluid moves the cylinders, which move cables attached to them, acting as tendons, and pulling on the robotic limbs.

Thus, the operator is imbued with superhero strength. He (or she) can lift 90kg with ease, and do 500 reps without breaking a sweat. The machine does all the work.

While Sarcos may have succeeded on one count, it has yet to solve a rather large problem: power. Thanks to the power demand of its hydraulic system, the current XOS remains tethered to an external power supply. A battery pack provides only 20 minutes of operation time.

Even so the XOS is the only full exoskeleton of the original batch that has been moved into the next stage of development.

On the other side of the Pacific Ocean, in Japan, Yoshiyuki Sankai, of the University of Tsukuba, has been developing his own breed of exo-skeleton.

In 2004, Sankai launched a company called Cyperdyne to market his full-body exoskeleton, the Hybrid Assistive Limb, or HAL, currently in its fifth incarnation.

This wearable robot integrates mechanics, electronics, bionics and robotics in a new field called cybernics. HAL-5 works by using bioelectric sensors attached to the skin to monitor signals transmitted from the brain to the muscles. When one attempts to move, the brain sends electrical impulses to the muscles.

When these impulses arrive at the muscles, faint bio-electrical signals appear on the skin's surface. The sensors pick up these currents, and send them to a computer, which interprets the signals and analyses how much strength the wearer intends to generate. The computer then sends its own signals to control electric motors in the joints of the exoskeleton. In fact, the motors of the exoskeleton respond a fraction of a second faster to the signals from the brain than the muscles of the wearer.

While this system moves individual elements of the exoskeleton, a second system provides autonomous robotic control of the motors to co-ordinate their movements.

HAL-5 not only assists with movement, but also enables the wearer to lift up to 40kg more than he/she would normally be able to. The suit itself weighs just 23kg (to the XOS's 68kg), but the wearer does not feel this weight. "It's like riding on a robot, rather than wearing one," says Sankai.

The suit includes a battery pack, which provides two hours 40 minutes of continuous operating time.

Unlike the Sarcos XOS, which is now being tailored for military use, HAL-5 is intended to be used for medical rehabilitation, support for people with physical disabilities, for use in heavy labour at factories and in rescue operations.

HAL-5 is intended to go into production this year, with about 500 to be produced each year.

Although neither the Sarcos XOS or HAL-5 includes such features as flame throwers or jet packs, or even impenetrable armour, the real Iron Man may not be that far off.

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