prosthetic devices to help disabled people walk better. (Author’s note: Herr was my faculty advisor in the Leg Lab when I was a postdoc.) “If the mission is to carry very heavy objects, or to lift an object from the floor to a table, then it clearly works,” he says.
So here’s my bottom line. A few things have improved: the hardware is cheaper, stronger, and lighter; the control is a little smoother; and the devices are more powerful. But two fundamental problems remain, and they are somewhat related.
One is mobility. Part of the original vision of the DARPA program was to create a suit that soldiers could wear to augment their movement capabilities in the field—think running 10 miles without breaking a sweat, or carrying around 200 pounds of equipment effortlessly. But when it comes to exoskeletons, Herr says he is “not aware of any improvements in locomotion” as of yet. Presumably that’s because strapping on bulky equipment changes people’s natural gait and makes it harder to walk smoothly.
For his part, Herr’s research group is working on a lightweight, low-power, lower-body exoskeleton focused not on increasing strength but on “allowing humans to get from point A to point B with less energy,” he says. Applications of such a device might include rehabilitation, defense, and sporting equipment—but it certainly won’t be easy to make it work right.
“Humans have evolved over millions of years,” Herr says. “Something like walking is highly refined. It’s exceedingly difficult to get a machine to improve on those efficient dynamics.”
The other big challenge in exoskeletons is how to power the device. Hydraulics is Raytheon’s preferred method. But hooking up a soldier or worker to a high-pressure fluid line won’t work in the field. So the company has devised a backpack-size internal combustion engine running on gasoline (or other liquid fuel); that power source drives hydraulic fluid to control the robotic joints. Clearly, a soldier won’t want to carry something noisy and smelly that could blow up in the field. But it’s very hard to do better than an internal combustion engine, in terms of delivering power efficiently. So this remains a great unsolved problem for exoskeletons—and robots in general.
And, much more broadly, for alternative energy. If scientists ever solve the portable energy problem, they will find many other things to apply it to besides exoskeletons. Whether it’s a fundamentally new kind of battery or energy storage device, or a new kind of fuel, it could potentially change the cleantech landscape. Indeed, the societal context around alternative energy and green technology has changed a lot more in the past decade than the issues around personal robotics.
The Boston area should help lead the way on these fronts. Besides Raytheon and MIT, Massachusetts is home to robotics companies like iRobot, Boston Dynamics (Leg Lab founder Marc Raibert’s company), CyPhy Works, Harvest Automation, Heartland Robotics, iWalk (Herr’s company), Myomo, and U.S. defense facilities such as the Natick Soldier Systems Center.
For my money, though, I would not expect to see a soldier, or anyone else, wearing an exoskeleton for at least another decade. Though it might make a nice Halloween costume in a few weeks.
