An exoskeleton suit has been developed that could help older people or those with disabilities to walk or lift heavy objects. Great photo.

Dubbed HAL, or hybrid assistive limb, the latest versions of the suit will be unveiled this June at the 2005 World Expo in Aichi, Japan, which opened last month. A commercial product is slated for release by the end of the year.

HAL is the result of 10 years’ work by Yoshiyuki Sankai of the University of Tsukuba in Japan, and integrates mechanics, electronics, bionics and robotics in a new field known as cybernics. The most fully developed prototype, HAL 3, is a motor-driven metal “exoskeleton” that you strap onto your legs to power-assist leg movements. A backpack holds a computer with a wireless network connection, and the batteries are on a belt.

Two control systems interact to help the wearer stand, walk and climb stairs. A “bio-cybernic” system uses bioelectric sensors attached to the skin on the legs to monitor signals transmitted from the brain to the muscles. It can do this because when someone intends to stand or walk, the nerve signal to the muscles generates a detectable electric current on the skin’s surface. These currents are picked up by the sensors and sent to the computer, which translates the nerve signals into signals of its own for controlling electric motors at the hips and knees of the exoskeleton. It takes a fraction of a second for the motors to respond accordingly, and in fact they respond fractionally faster to the original signal from the brain than the wearer’s muscles do.

“The motors respond faster to signals from the wearer’s brain than their own muscles”While the bio-cybernic system moves individual elements of the exoskeleton, a second system provides autonomous robotic control of the motors to coordinate these movements and make a task easier overall, helping someone to walk, for instance. The system activates itself automatically once the user starts to move. The first time they walk, its sensors record posture and pattern of motion, and this information is stored in an onboard database for later use. When the user walks again, sensors alert the computer, which recognises the movement and regenerates the stored pattern to provide power-assisted movement. The actions of both systems can be calibrated according to a particular user’s needs, for instance to give extra assistance to a weaker limb.

The HAL 4 and HAL 5 prototypes, which will also be demonstrated at Expo 2005, don’t just help a person to walk. They have an upper part to assist the arms, and will help a person lift up to 40 kilograms more than they can manage unaided. The new HALs will also eliminate the need for a backpack. Instead, the computer and wireless connection have been shrunk to fit in a pouch attached to the suit’s belt. HAL 5 also has smaller motor housings, making the suit much less bulky around the hips and knees.

HAL 3 weighs 22 kilograms, but the help it gives the user is more than enough to compensate for this. “It’s like riding on a robot, rather than wearing one,” says Sankai. He adds that HAL 4 will weigh 17 kilograms, and he hopes HAL 5 may be lighter still.

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