A 'Robotic Shorts' that make it easier to walk and run

Harvard University researchers have developed a new powered exosuit that can make you feel as much as a dozen pounds lighter when walking or running. Scientific American reports that the 11-pound system, which is built around a pair of flexible shorts and a motor worn on the lower back, could benefit anyone who has to cover large distances by foot, including recreational hikers, military personnel, and rescue workers.

According to the researchers, who have published their findings in the journal Science, this system differs from previous exosuits because it’s able to make it easier to both walk and run. The challenge, as shown by a video accompanying the research, is that your legs work very differently depending on whether you’re walking or running. When walking, the team says your center of mass moves like an “inverted pendulum,” while running causes it to move like a “spring-mass system.” The system needs to be able to accommodate both of them, and sense when the wearer’s gait changes.

The exosuit works by connecting motors worn on the lower back to the wearer’s thighs through a series of actuation cables. By applying force to these cables, the system is able to assist the gluteal muscles in powering the legs. The whole setup is powered by a waist-mounted battery which has enough range for around five miles. The exosuit has a total combined weight of 11 pounds, although the same team is currently developing a system that weighs 40 percent less.

By having someone run and walk on a treadmill while wearing the shorts and measuring the amount of oxygen they consumed while breathing, the researchers calculated that the metabolic cost of walking and running were reduced by 9.3 and 4 percent respectively, compared to running without wearing the shorts. That change in effort is the equivalent of feeling 16.3 pounds or 12.6 pounds lighter, respectively.

As well as helping people who need to cover large distances on foot, the team hopes that system could one day help anyone with a disability that restricts walking. Inevitably, as the research’s connection to the Defense Advanced Research Project Agency (DARPA)’s Warrior Web program suggests, the suit’s users could also include military personnel, who frequently have to carry dozens of pounds of gear by foot. The Warrior Web program is tasked with developing technologies that reduce the strain of carrying so much equipment.

The exosuit isn’t without its limitations. The photos make the system look very bulky, especially on the lower back, where it would limit the wearer’s ability to carry a full-sized backpack. The system is also designed around male walking styles since it can be difficult to tailor exoskeletons to individual body shapes and movement styles. Scientific American reports that new versions are currently in development for women, however.

The researchers have been putting the exosuit through its paces in a controlled laboratory setting so far, but the hope is that future studies could evaluate the device in more real-world environments. The team also hopes to expand the approach to assist industry workers performing “physically strenuous tasks” as well as people with “gait impairments.”
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