A lone soldier stands in a dark alley, eyeing a door. Even though he’s covered in bulky armor, he charges forward and bursts through, and is engulfed in a barrage of gunfire. Rather than retreat, the soldier stands tall as bullets ping off him harmlessly.
This isn’t a trailer for the latest superhero movie. It’s an animation produced by the U.S. military, designed to show off its vision for a brawny robotic exoskeleton that it hopes to deploy with elite commandos. Dubbed the Tactical Assault Light Operator Suit, or TALOS, it’s the focus of a multimillion dollar research project catalyzed by a commando’s death during a hostage rescue in Afghanistan. The TALOS’s name pays homage to a metal giant of Greek mythology who guarded the island of Crete, effortlessly circling it three times a day. More casually, it is called the Iron Man suit.
The TALOS is just one part of a much larger, global research push to develop exoskeletons that would endow people with superhuman strength and endurance. But imagining Iron Man in comic books and movies has proven easier than building him. The effort is littered with failures. A predecessor to the TALOS, called the Human Universal Load Carrier (HULC), was shelved after it proved impractical, exhausting users instead of supercharging them. And some scientists are skeptical that the TALOS and similar heavy, hard-bodied exoskeleton designs will work anytime soon, saying they often fail to address fundamental physiological issues.
Improving on the effortlessness of the human stride—little more than a forward lean and a flick of the calf—turns out to be a daunting engineering challenge. Building a machine to help someone with a disability is one thing, but “it’s very difficult from a design perspective to augment human walking and running, because we’re so good at it,” says Hugh Herr, an engineer at the Massachusetts Institute of Technology (MIT) in Cambridge. The exoskeletons developed so far, he says, are too bulky and tend to fight the natural rhythms of the body, which turns them into “fancy exercise machines.”
As a result, some researchers are lowering their sights. They are taking a softer, smaller approach, building suits that resemble running tights hooked to motorized wires, or a modest ankle brace. In just the last few years, they have finally achieved a long-sought goal: creating an exoskeleton that actually saves the user energy while walking on a level treadmill.
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