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.
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"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.