CAMBRIDGE — A new type of wearable robotic technology could one day give ordinary people the power to finish a marathon in less than two hours.
But before achieving that feat, a team at Harvard and the University of Nebraska Omaha needed to perfect its latest version of an exosuit to make it easier for a person wearing it to walk and run efficiently.
Previous exosuits could only identify a single gait — walking or running — but not both, said researchers. They lacked the ability to smoothly transition between strolling and sprinting without breaking stride.
“This is a milestone for the field,” said Jinsoo Kim, the co-first-author of the study published Thursday in Science, an academic journal. “It highlights the potential of the system for everyday activities, not just one activity in the lab.”
The new exosuit is intended to help soldiers and first-responders who are working under strenuous situations, said Kim, an engineering graduate student at Harvard. The technology could potentially alleviate fatigue incurred while traveling distances or carrying heavy loads, researchers predict.
“When you wear it, you forget you’re wearing it,” said Ignacio Galiana, one of the robotics engineers involved in the study. He likened the device to power-steering systems that drivers often take for granted.
The new exosuit is made of a lightweight fabric and includes a thigh wrap and waist belt, which weaves together an intricate web of cables. The electric motor and a controller unit, some of the heaviest parts of the roughly 5-kilogram device, is positioned on a person’s back and emits a subtle whirring noise.
Sensors on the user’s thighs and abdomen are programmed to detect motion, Kim said. Using a pulley system that works with a user’s internal muscles, the battery-equipped suit delivers support to the hip joint, all in a nearly instantaneous calculation.
Exosuits work by reducing a person’s energy consumption.
Through testing on a treadmill, the team discovered that participants who wore the device decreased their metabolic rate by about 9 percent while walking and 4 percent while running. That potentially translates into performance gains for the user, said Philippe Malcolm, a co-corresponding author on the study.
“In theory, that should allow a person to carry extra loads at the same speed, or arrive more rested at the scene,” said Malcolm, an assistant professor at the University of Nebraska Omaha.
Researchers in the lab recently developed an exosuit to help stroke patients regain mobility in physical therapy, working in collaboration with ReWalk Robotics, a medical device company, which builds and sells the devices.
Other applications are in progress for people suffering from Parkinson’s disease and multiple sclerosis, Kim said.
Conor Walsh, a Harvard professor who was the study’s principal investigator, is also developing exosuits to improve safety in industrial settings, such as an automotive factory, where workers might strain their backs lifting heavy machinery.
The study was funded by two federal agencies, the Defense Advanced Research Projects Agency and the National Defense Foundation, Walsh said.
It was awarded to Harvard’s Wyss Institute for Biologically Inspired Engineering and the John A. Paulson School of Engineering and Applied Sciences, as well as the University of Nebraska Omaha.
Researchers said they ultimately want to improve exosuits’ designs to make them user-friendly and widely available to the public.
To achieve the exoskeleton’s dual mobility, the team reconciled biomechanical differences between walking and running.
When people walk, their legs move back and forth like an inverted pendulum, Malcolm said. Running creates a motion similar to a spring bouncing up and down.
For the exosuit to work, it must accurately determine whether the person is running or walking before applying the right force at the right time to the user’s hip joint.
“If you get it wrong, you can really make it hard for a person to walk,” Walsh said.
The wrong identification could result in a user exerting approximately 30 percent more energy.
The exosuit’s versatility remains a work in progress. Researchers said they hope to decrease its weight by 2 kilograms, an energy- and cost-saving measure.
Another goal entails customizing the device for people’s unique gaits, they said.
All individuals have a peculiar style of propelling their bodies forward, Kim said. If the suit exerts a more precise force, users could minimize their metabolic energy consumption, he said.
And Kim envisions equipping the exosuit with other capabilities, including being able to help people climb stairs or jump around.
“Maybe, this exosuit needs to carry out all these different activities,” he mused.
Alison Kuznitz can be reached at firstname.lastname@example.org.