Really Special Forces
A powered exoskeleton could transform the average joe into a super soldier 

From: Discover - February 2002 - page 25
By: Brad Lemley

Lamont Drechel is a mild-mannered mechanical engineer, but right now he looks
like the violent offspring of G.I. Jane and Robocop. Clad in camouflage
fatigues, he is strapped into a Plexiglas framework hinged at his elbows,
hips, and other joints to follow his movements. He kneels, stretches, and
casts menacing glances around a machine shop at Sarcos, the Salt Lake City,
UT, engineering firm that made the apparatus. "It's surprisingly
comfortable," he says, breaking into a grin. "I feel like I can do pretty
much whatever I want." Drechsel's sense of freedom will expand even more once
he and his colleagues attach pistons to the hinges, each firing in response
to his subtlest finger twitch or leg flex. The result will be an exoskeleton
- essentially a powered suit of armor. Such a device could give a soldier a
huge advantage in battle. "We want to give our troops at least a
two-horsepower augmentation of strength and endurance," says Ephrahim Garcia,
who directs the exoskeleton program for the Defense Advanced Research
Projects Agency, often called DARPA for short. Last spring, the agency doled
out the first grants from its $50 million Exoskeletons for Human Performance
Augmentation project to Sarcos, Oak Ridge National Laboratory, and the Human
Engineering Laboratory at the University of California at Berkeley. The
mandate: Have a legs-only exoskeleton ready for trials by 2003 and a
whole-body version by 2005.  

Wearing a device built to DARPA specs, a grunt, without grunting, could heft
400 pounds, including bigger weapons, bulletproof armor, better
communications devices, and more food, and remain continuously active for at
least four hours. Exoskeletons could be optimized for other combat tasks,
too, such as running much faster than ordinary humans, jumping over fences,
or picking up rubble during rescue efforts. Add a soupcon of artificial
intelligence and the suit could save its wearer if he is wounded. "You could
send a command to take this guy home," says Stephen Jacobsen, CEO of Sarcos.  

The program to create a powered exoskeleton springs from the premise that
future warfare will be urban. Soldiers will need to climb stairs, dart
through narrow alleys, and leap from rooftops, none of which can be done in
tanks or airplanes. But Francois Pin, who heads the Oak Ridge effort, sees
dozens of non-military uses as well. "Construction is a $4 billion industry
in this country, and it's very primitive. We are injuring people every day.
Cargo handling, search and rescue - the possibilities are endless." 
Ultimately, exoskeletons could transform society. The elderly could regain
the physical abilities of youth, and paraplegics could walk. "This is a dream
that's buried in everyone's psyche. Everybody wants to be strong," Jacobsen
says.  

Because of that deep appeal, the idea of exoskeletons is far from new. Robert
A. Heinlein swaddled soldiers in powered armor in his 1959 novel Starship
Troopers, and in the 1986 film Aliens, a machine-enhanced Sigourney Weaver
slaps around one of the title characters.  

Although fiction has outpaced real life, participants in the exoskeleton
project believe advances in power generation, microprocessors, and control
technologies are finally bringing the dream within reach. "I truly believe
that in five years, we will be there," says Homayoon Kazerooni, director of
Berkeley's Human Engineering Laboratory. Still, even optimists like Jacobsen
recognize the magnitude of the challenge. "There are large technical hurdles
at every level," he says.  

The main problem is power. Actuators - the robotic equivalent of muscles -
must be strong, efficient, durable, controllable, and quiet, none of which is
easily accomplished. Sarcos is among the world's leading robotics firms,
having built everything from undersea salvage robots for the Navy to
animatronic buccaneers for The Walt Disney Company's Pirates of the Caribbean
rides. With most such devices, however, "there's a dirty little secret in the
next room," says Jacobsen. "Electrical stuff has a big generator somewhere.
Hydraulics has a hidden motor and pump. With this machine, you don't get to
have that dirty secret?" The key to success, he thinks, is to find a way to
emulate the efficiency of muscle tissue. "Muscle is so damn good at this
stuff. If you took all of the muscles off of a healthy adult male and put
them in full contraction, they would lift 20 tons. And they run on carrots."  

"Each of the labs has a different idea about skinning this cat," says Pin.
His Oak Ridge team plans to use a fuel cell to power hydraulic actuators.
Sarcos's suit will incorporate a separate, hydrogen- or petroleum-fired
piston at every joint, an approach that aims to avoid the losses that plague
distributed-power systems. Kazerooni's lab in Berkeley will be experimenting
with a pneumatic system powered by hydrogen peroxide. So far, nobody has an
actuator that approaches the required efficiencies.  

Although power issues remain thorny, control technologies have come a long
way over the past decade. In the late 1990s, Pin's group built an artificial
arm that responds instantly to commands and can load 4,000-pound bombs into
F-15 jet bays. The operator grabs a handle-like device at the end of the
arm's framework, and the machine follows his motions, providing
force-feedback so he can feel the bomb's weight, shape, and inertia. "We had
young guys from the Air Force who had never seen a computer; they were
successfully loading bombs with this thing in 15 minutes," Pin says.  

But in a whole-body exoskeleton, the force-feedback mechanism must be
extremely subtle. Sarcos has extensive experience with building master-slave
systems, in which a person wearing a control harness directs the movements of
a robot. "We've discovered that humans don't do well under constant load.
Even if you have to push with just a pound or two of force, you get tired
very quickly," says Jacobsen. The exoskeleton, he says, "should barely touch
you but be extremely responsive?" Sarcos has pioneered sensors that allow
amputees to control mechanical arms through tiny movements of skin or muscle,
but whether such sensors can work on a fully clothed soldier in a whole-body
exoskeleton remains to be seen.  

If any lab does succeed, exoskeletons may quickly appear in a bewildering
variety of forms. Kazerooni expects partial versions will hit the market
first. "A factory worker might have just a pair of enhanced arms," he says.
"There will be many job-specific applications for arms alone or legs alone?'  

Jacobsen is particularly excited about the potential for powered legs. "About
3 percent of the world can be accessed in a wheeled vehicle, but 85 percent
can be reached by something with legs," he says. He envisions a
centaur-truck: A human being wears and controls the front set of legs, while
one or more leg pairs follow along behind, supporting a flatbed. "You could
transport cargo anywhere," he says. Later there could be a market for many
types of whole-body suits as well. "Just as there are little cars, big cars,
and big trucks, there will be specialized suits for all kinds of tasks," he
predicts.  

Power is the crucial missing element, Jacobsen believes. Everything else is
difficult but doable. "Motors, more than anything else, are what made
airplanes possible," he says. "This is similar. People wanted to fly, and the
development happened. Whatever gets water, grows. Now, this is getting
water?."  

http://www.darpa.mil/dso/thrust/md/Exoskeletons/garcia.html
http://www.darpa.mil/dso/solicitations/00/Baa00-34/cbd.htm
http://www.sarcos.com/index1.html
http://www.me.berkeley.edu/hel/
