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Robotic Advances Promise Artificial Legs That Emulate Healthy Limbs
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Details — Recent advances in robotics technology make it possible to
create prosthetics that can duplicate the natural movement of human
legs. This capability promises to dramatically improve the mobility of
lower-limb amputees, allowing them to negotiate stairs
and slopes and uneven ground, significantly reducing their risk of
falling as well as reducing stress on the rest of their bodies.


That is the view of Michael Goldfarb, the H. Fort Flowers Professor of
Mechanical Engineering, and his colleagues at Vanderbilt University's
Center for Intelligent Mechatronics expressed in a perspective's article
in the Nov. 6 issue of the journal Science Translational Medicine.


For the last decade, Goldfarb's team has been doing pioneering research
in lower-limb prosthetics. It developed the first robotic prosthesis
with both powered knee and ankle joints. And the design became the first
artificial leg controlled by thought when researchers at the
Rehabilitation Institute of Chicago created a neural interface for it.
In the article, Goldfarb and graduate students Brian Lawson and Amanda
Shultz describe the technological advances that have made robotic

prostheses viable. These include lithium-ion batteries that can store
more electricity, powerful brushless electric motors with rare-Earth
magnets, miniaturized sensors built into semiconductor chips,
particularly accelerometers and gyroscopes, and low-power computer
chips.

The size and weight of these components is small enough
so that they can be combined into a package comparable to that of a
biological leg and they can duplicate all of its basic functions. The
electric motors play the role of muscles. The batteries store enough
power so the robot legs can operate for a full day on a single charge.
The sensors serve the function of the nerves in the peripheral nervous
system, providing vital information such as the angle between the thigh
and lower leg and the force being exerted on the bottom of the foot,
etc. The microprocessor provides the coordination function normally
provided by the central nervous system. And, in the most advanced
systems, a neural interface enhances integration with the brain. Unlike
passive artificial legs, robotic legs have the capability of moving
independently and out of sync with its users movements. So the
development of a system that integrates the movement of the prosthesis
with the movement of the user is "substantially more important with a
robotic leg," according to the authors. Not only must this control
system coordinate the actions of the prosthesis within an activity, such
as walking, but it must also recognize a user's intent to change from
one activity to another, such as moving from walking to stair climbing.
Identifying the user's intent requires some connection with the central
nervous system.

Currently, there are several different
approaches to establishing this connection that vary greatly in
invasiveness. The least invasive method uses physical sensors that
divine the user's intent from his or her body language. Another method
-- the electromyography interface -- uses electrodes implanted into the
user's leg muscles. The most invasive techniques involve implanting
electrodes directly into a patient's peripheral nerves or directly into
his or her brain. The jury is still out on which of these approaches
will prove to be best. "Approaches that entail a greater degree of
invasiveness must obviously justify the invasiveness with substantial
functional advantage…," the article states.

Source: Science Daily
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 سپاس شده توسط emad akrami ، Dash @li
#2
oh،yeah ok
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 سپاس شده توسط Hossein.J


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