Wednesday, April 20, 2011
US scientists take steps to making 'bionic' leg
As 20-year-old Hailey Daniswicz flexes muscles in her thigh, electrodes attached to her leg instruct a computer avatar to flex its knee and ankle - parts of Hailey's leg that have been missing since 2005.
Daniswicz, a sophomore at Northwestern University who lost her lower leg to bone cancer, is training the computer to recognize slight movements in her thigh so she can eventually be fitted with a "bionic" leg - a robotic prosthesis she would control with her own nerves and muscles.
"We're really integrating the machine with the person," said Levi Hargrove, a research scientist at the Rehabilitation Institute of Chicago's Center for Bionic Medicine who is leading the project.
Daniswicz is part of a clinical trial sponsored by the US Army that is using electromyography - electrical signals produced by muscles - and pattern recognition computer software to control a new generation of robotic limbs.
Electrodes attached to nine different muscles in the thigh act as antennas, picking up electrical signals sent from the nerves to the muscles. These signals are fired in a specific pattern depending on how a person intends to move.
With a bit of training, the computer can learn a person's signal pattern for when they want to bend a knee or flex an ankle and it makes the virtual reality avatar move.
"The way most prosthetics work now is you have mechanical sensors. You have to push and interact with them," Hargrove said. "With this, you measure the actual neural intent and have that tell the motor what to do."
Researchers at the institute have already developed prosthetic arms directed by nerve impulses. But a robotic leg would give lower limb amputees a new kind of freedom, allowing them to climb stairs more safely and with more natural motion.
Daniswicz has been training her computer avatar since January and she can now instruct it to bend and straighten its knee, and flex and straighten its ankle, just by making slight movements in her thigh muscles.
"Hailey has taught the computer what to do, and now, whenever she does it, it listens, interprets and makes the leg on the virtual reality avatar move," Hargrove said.
Daniswicz is one of four volunteers in the study trial that set out to determine whether patients would need surgery to implant additional nerve endings - a technique called targeted muscle reinnervation - to control the motorized leg.
Daniswicz, a sophomore at Northwestern University who lost her lower leg to bone cancer, is training the computer to recognize slight movements in her thigh so she can eventually be fitted with a "bionic" leg - a robotic prosthesis she would control with her own nerves and muscles.
"We're really integrating the machine with the person," said Levi Hargrove, a research scientist at the Rehabilitation Institute of Chicago's Center for Bionic Medicine who is leading the project.
Daniswicz is part of a clinical trial sponsored by the US Army that is using electromyography - electrical signals produced by muscles - and pattern recognition computer software to control a new generation of robotic limbs.
Electrodes attached to nine different muscles in the thigh act as antennas, picking up electrical signals sent from the nerves to the muscles. These signals are fired in a specific pattern depending on how a person intends to move.
With a bit of training, the computer can learn a person's signal pattern for when they want to bend a knee or flex an ankle and it makes the virtual reality avatar move.
"The way most prosthetics work now is you have mechanical sensors. You have to push and interact with them," Hargrove said. "With this, you measure the actual neural intent and have that tell the motor what to do."
Researchers at the institute have already developed prosthetic arms directed by nerve impulses. But a robotic leg would give lower limb amputees a new kind of freedom, allowing them to climb stairs more safely and with more natural motion.
Daniswicz has been training her computer avatar since January and she can now instruct it to bend and straighten its knee, and flex and straighten its ankle, just by making slight movements in her thigh muscles.
"Hailey has taught the computer what to do, and now, whenever she does it, it listens, interprets and makes the leg on the virtual reality avatar move," Hargrove said.
Daniswicz is one of four volunteers in the study trial that set out to determine whether patients would need surgery to implant additional nerve endings - a technique called targeted muscle reinnervation - to control the motorized leg.
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