Motor-Free Device Reduces Stress from Walking.doc

Motor-Free Device Reduces Stress from Walking Devices that help people walk were once thought to be difficult, if notimpossible, to design. Until recently, such a device required electricity from anexternal power supply. Now, American scientists have built a small, wearableaddition to normal shoes. Their new invention eases the load on muscles in the leg and makes walking easier. Steven Collins and Greg Sawicki are biomedical engineers. They both studiedhow human beings walk. They found that our ankles and calves performmotions similar to a spring joined to a clutch. In an automobile, a clutch isused to connect and disconnect a driving or driven part of an engine or otherpiece of equipment. The researchers found that the human body parts areable to both store and release energy, just like a spring. Steven Collins works with Carnegie Mellon University in Pennsylvania. GregSawicki is with North Carolina State University. He spoke to VOA on Skype. We found in basic science experiments that that system, your calf andAchilles tendon, works a lot like a catapult. So, the muscle holds on to thetendon and your body actually stretches your Achilles tendon quite a bit andthen stores the energy in the tissue and then its given back to propel youforward in the world. Mr. Sawicki says he and Mr. Collins designed a mechanical device thatperforms the same kind of energy ‘give-and-take’ outside the body. Their newankle exoskeleton is made of carbon fiber and metal. It connects to ordinaryshoes and takes over part of the work of walking. Mr. Sawicki says thedevice reduces the amount of energy required for walking by as much asseven percent. The unpowered ankle exoskeleton can help people walk farther with the sameamount of energy. It also can restore normal movement for individuals whohave trouble walking. Mr. Sawicki says it takes only a few minutes for someone to get used to theankle exoskeleton. He says the wearer quickly learns to use less muscleenergy, letting the device do muc