This article is from the source 'guardian' and was first published or seen on . It last changed over 40 days ago and won't be checked again for changes.

You can find the current article at its original source at http://www.theguardian.com/science/2015/apr/01/lower-leg-exoskeleton-could-take-the-work-out-of-walking

The article has changed 2 times. There is an RSS feed of changes available.

Version 0 Version 1
Lower-leg exoskeleton could take the work out of walking Lower-leg exoskeleton could take the work out of walking
(35 minutes later)
The market is undoubtedly there. Country strolls. Visits to museums. Weekend shopping trips. How much easier they would be wearing an unpowered, lower-leg, carbon fibre exoskeleton.The market is undoubtedly there. Country strolls. Visits to museums. Weekend shopping trips. How much easier they would be wearing an unpowered, lower-leg, carbon fibre exoskeleton.
Though cumbersome to say, the device itself is sleek and simple, using only a spring, wire and clutch mounted on a carbon fibre frame to take some of the slog out of bipedal locomotion.Though cumbersome to say, the device itself is sleek and simple, using only a spring, wire and clutch mounted on a carbon fibre frame to take some of the slog out of bipedal locomotion.
The gadget makes its debut today in a report from US researchers, who found that the mechanical aid reduced the energy needed for walking by 7%, the equivalent of shedding half a stone (4kg) of bodyweight. To specialists in biomechanics, at least, that is quite a feat.The gadget makes its debut today in a report from US researchers, who found that the mechanical aid reduced the energy needed for walking by 7%, the equivalent of shedding half a stone (4kg) of bodyweight. To specialists in biomechanics, at least, that is quite a feat.
“Given that we have had 7 million years to evolve structures and traits for walking, and tens of thousands of hours of practice, we wanted to see if it was even possible to reduce the energy we use for walking,” said Steven Collins, who designed and built the device at Carnegie Mellon University in Pittsburgh.“Given that we have had 7 million years to evolve structures and traits for walking, and tens of thousands of hours of practice, we wanted to see if it was even possible to reduce the energy we use for walking,” said Steven Collins, who designed and built the device at Carnegie Mellon University in Pittsburgh.
Our muscles are fantastic in many ways, says Collins. They grow to meet our needs, heal themselves when injured, and run on organic fuels found all around us. But they are not particularly efficient. “When they produce positive work, they have a conversion efficiency of about 25%, which is about the same as an internal combustion engine in a car,” Collins said.Our muscles are fantastic in many ways, says Collins. They grow to meet our needs, heal themselves when injured, and run on organic fuels found all around us. But they are not particularly efficient. “When they produce positive work, they have a conversion efficiency of about 25%, which is about the same as an internal combustion engine in a car,” Collins said.
Engineers have dabbled for years with powered exoskeletons to help people walk, run or lift heavy objects. But they are heavy. They use motors or hydraulic systems, and have batteries that need constant recharging. “The cool thing about unpowered exoskeletons is that they are light, don’t need recharging, and could be really inexpensive,” said Collins.Engineers have dabbled for years with powered exoskeletons to help people walk, run or lift heavy objects. But they are heavy. They use motors or hydraulic systems, and have batteries that need constant recharging. “The cool thing about unpowered exoskeletons is that they are light, don’t need recharging, and could be really inexpensive,” said Collins.
The device he created, with colleagues at North Carolina State University, attaches around the shin and clips under the foot. Behind the calf, a spring, wire and clutch perform much the same job as the muscle and Achilles tendon. When the wearer’s foot touches the ground, the clutch locks the wire, making the spring stretch as the person walks forwards. When their foot lifts off, the clutch disengages and the spring relaxes, ready for the next step. “It takes the load off the calf muscles, so it reduces the amount of energy they expend in contractions,” Collins said.The device he created, with colleagues at North Carolina State University, attaches around the shin and clips under the foot. Behind the calf, a spring, wire and clutch perform much the same job as the muscle and Achilles tendon. When the wearer’s foot touches the ground, the clutch locks the wire, making the spring stretch as the person walks forwards. When their foot lifts off, the clutch disengages and the spring relaxes, ready for the next step. “It takes the load off the calf muscles, so it reduces the amount of energy they expend in contractions,” Collins said.
In treadmill tests, the researchers report in Nature, the exoskeleton reduced the amount of energy expended on walking by 4.6 to 9.8%, or an average of about 7%. The improvement takes into account the extra energy used in carrying the weight of the exoskeleton, which comes in at about 0.5kg for each leg.In treadmill tests, the researchers report in Nature, the exoskeleton reduced the amount of energy expended on walking by 4.6 to 9.8%, or an average of about 7%. The improvement takes into account the extra energy used in carrying the weight of the exoskeleton, which comes in at about 0.5kg for each leg.
“When you first put it on it feels a bit odd, but once you’ve walked with it for a while, it starts to feel quite comfortable,” Collins said. “But it’s when you take it off that you really feel a big difference. Your leg feels heavy and weak.”“When you first put it on it feels a bit odd, but once you’ve walked with it for a while, it starts to feel quite comfortable,” Collins said. “But it’s when you take it off that you really feel a big difference. Your leg feels heavy and weak.”
The prototype has some wrinkles that need to be ironed out. The tranquility of a countryside walk might broken by the regular metallic twang that follows the wearer around. Stairs pose another problem. “There’s a lever that sticks out at the back of the heel about 10cm. That makes going downstairs an invitation to disaster. So there are lots of little things that would need to be improved before it was a real product,” said Collins.The prototype has some wrinkles that need to be ironed out. The tranquility of a countryside walk might broken by the regular metallic twang that follows the wearer around. Stairs pose another problem. “There’s a lever that sticks out at the back of the heel about 10cm. That makes going downstairs an invitation to disaster. So there are lots of little things that would need to be improved before it was a real product,” said Collins.
Collins says he was motivated in part by sheer scientific curiosity, to see if he could improve the efficiency of human walking. But he hopes that a future version of the device could alleviate the effort of walking for disabled people. People who have had strokes, for example, can use much more energy walking around, because their coordination may be worse, and in time, their muscles weaken.Collins says he was motivated in part by sheer scientific curiosity, to see if he could improve the efficiency of human walking. But he hopes that a future version of the device could alleviate the effort of walking for disabled people. People who have had strokes, for example, can use much more energy walking around, because their coordination may be worse, and in time, their muscles weaken.
“A more sophisticated version could be used by recreational hikers, casual runners to keep up with their more fit companions, or first responders, such as nurses,” he said. “For a lot of people who walk a lot in their jobs, for hours and hours on end, fatigue can be a limiting factor.”“A more sophisticated version could be used by recreational hikers, casual runners to keep up with their more fit companions, or first responders, such as nurses,” he said. “For a lot of people who walk a lot in their jobs, for hours and hours on end, fatigue can be a limiting factor.”
The exoskeleton raises another question that comes up whenever Collins gives a talk on the device. Even though it could help disabled and elderly people, walking is the only exercise some individuals get. Might his device, perversely, put people even more at risk of being overweigh or obese? “It’s a good suspiscion,” he said. “But it’s not clear whether reducing the energy of each step would reduce people’s exercise from walking over, say, a week. It could be that if each step is easier, people take more of them.” The exoskeleton raises another question that comes up whenever Collins gives a talk on the device. Even though it could help disabled and elderly people, walking is the only exercise some individuals get. Might his device, perversely, put people even more at risk of being overweigh or obese? “It’s a good suspicion,” he said. “But it’s not clear whether reducing the energy of each step would reduce people’s exercise from walking over, say, a week. It could be that if each step is easier, people take more of them.”
Robert McNeill Alexander, a specialist in human movement at Leeds University, had reservations about the device. “I’m 80 years old and because of my back, walking is very hard work. But a 7% saving isn’t very much. You’d be better off on a bicycle.”Robert McNeill Alexander, a specialist in human movement at Leeds University, had reservations about the device. “I’m 80 years old and because of my back, walking is very hard work. But a 7% saving isn’t very much. You’d be better off on a bicycle.”
He went on to explain that when running, a human expends 280 joules of energy per metre covered. The energy used for cycling varies with speed, but at 6 metres per second, a person uses only 40 joules per metre on a bike, he said.He went on to explain that when running, a human expends 280 joules of energy per metre covered. The energy used for cycling varies with speed, but at 6 metres per second, a person uses only 40 joules per metre on a bike, he said.
“You might not be able to cycle around a shopping centre, but as it is, you’d look pretty peculiar with all this stuff attached to your leg. People would be roaring with laughter”.“You might not be able to cycle around a shopping centre, but as it is, you’d look pretty peculiar with all this stuff attached to your leg. People would be roaring with laughter”.