Exoskeleton Helps With Heavy Loads
March 11, 2004 -- How would you like to be able to climb your favorite mountain with a 100-pound backpack that feels like it weighs a little more than your lunch and an extra pair of shoes?
If Homayoon Kazerooni gets his wish, you won't have to wait more than a few years to hook up his "exoskeleton" and quite literally take a load off your back. Kazerooni is professor of mechanical engineering, and director of UC Berkeley's Robotics and Human Engineering Laboratory, and he's got a contraption in his lab that will add mechanical muscles to your body without having to take a single steroid.
The Berkeley Lower Extremity Exoskeleton, known affectionately as "Exo" to Kazerooni was developed with funding from the Defense Advanced Research Projects Agency, or DARPA, the Pentagon's effort to fund research on projects that to some people might seem a bit over the top. But Kazerooni's Exo is serious stuff, with possible applications ranging from fire fighting to combat to mountain climbing.
Firefighter Tool?
In his crystal ball, he sees the day when a fire fighter might be able to charge up stairs carrying equipment that would normally be far to heavy to manage, or a medic might be able to single-handedly carry out a wounded colleague, or a rescue worker might be able to carry in enough food and supplies to satisfy the needs of a small community."
"This is a machine that does not require any push buttons, steering wheels, key boards, joy sticks, or anything like that," Kazerooni says. "You don't drive the machine. You become an integral part of Exo while you are walking, and Exo carries the load."
He admits it's a bit awkward at times, and it's not all that hard for someone else to push you over, along with your 100-pound backpack, but this is still pretty early in research that can only be described as pioneering.
Most of us think of robots as those gold-plated dune buggies that are now grinding out the miles on Mars, but that kind of robotics is only part of the story. Those robots have to be largely self sufficient, even making some decisions through artificial intelligence.
Kazerooni's lab is deeply involved in the development of robots that rely on human intelligence for their commands, although the human doesn't have to even be aware of that.
"The human provides the intelligence control system for the exo, but the Exo actually provides most of the strength that is needed to perform a task," says Kazerooni.
An Engine in Your Legs
The machine looks a little like a metal skeleton, strapped to the boots and legs of the operator, called the "pilot." Computer-driven sensors detect the movement of the pilot, and hydraulic actuators flex the legs to carry the weight of the entire system, as well as a payload of at least 70 pounds.
"Exo" constantly calculates what it needs to do so that very little weight is imposed on the pilot. If the pilot moves one leg forward, for example, the computer instantly orders the hydraulics to extend Exo's leg forward just enough to carry the load.
That takes a fair amount of energy, and most researchers would rely on electric motors to get the job done, but Kazerooni desperately wants Exo to be more that just another laboratory exercise. So electric motors were out, because that would require a heavy battery pack or a very long extension cord.
So instead, Kazerooni and his Berkeley team turned to the kind of device that has driven industrial society for more than a century now — the internal combustion engine.
A tiny engine, like the type used in model aircraft, runs the entire contraption because as Kazerooni says, "you can get a lot of energy from one gallon of gasoline." So one of the things that makes this robot unique is it can be refueled in the field, using a fuel that is commonly available.
Of course, those model airplane engines are noisy as heck, but the researchers have made progress in reducing the noise. It will need to get a lot quieter though, to be of much use or it will spoil many a walk and reduce the number of applications. A quieter version is due out by late summer.
Powered by Human Network
"Exo" also takes computer networking to a new level. Since the sensors and hydraulics need to communicate with each other, they are tied together through a Local Area Network (LAN,) similar to the kind used in offices and homes around the world. But this one becomes part of the pilot, so Kazerooni calls it a "bodyLAN."
What's neat about the bodyLAN is it can transmit data from the Exo to a monitor somewhere else, say at a combat command post.
"Someone else might be able to tell that an ankle is broken, or the soldier isn't walking anymore," Kazerooni says.
That technology could easily be transferred to such things as helmets worn by fire fighters, he says.
To be honest, Exo doesn't look like the kind of gadget you would want to wear to the prom, and Kazerooni admits there are still a lot of bugs in the system. He says that when one of his researchers tried it on for the first time, "my knees were shaking" because he wondered what would happen if his co-worker fell down with all that extra weight.
So Kazerooni tried it on himself, and he immediately saw the potential, but he also saw the weaknesses.
"It's a little rough right now, because we are at the beginning stage," he says. "If you push on me when I am wearing the machine, I will fall. If you push on me a little, I won't fall because I can recover. The way I recover is a function of my ability and my skills to keep from falling."
So that calls for a little training, and more research.
Kazerooni wants to see the day when a pilot can run and jump while wearing Exo, and ultimately, even climb mountains.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.