Is Your Exoskeleton Ready for Primetime?
Wearable robotic exoskeletons can be a game changer. But the tech may still be too hard on your brain.
While at the mention of exoskeletons—or wearable mobile apparatuses, as they are called in marketing brochures—scenes of Tony Stark in his Iron Man armor elegantly zipping and hovering start to flicker in our minds, we often forget the test scenes where he struggles to control his flight and shoots himself straight into a wall. And this highlights the often overlooked, burdensome reality of exoskeletons: You can’t just slip on a mechanical, superpower-enabling exoskeleton “suit” (several types of which already exist) and operate it without burning lots of brain power to control the damn thing.
Although constantly evolving and improving, past iterations of exoskeleton mechanized gear have been abandoned for their inaccessibility and difficulty of use, after they have been shown to frustrate the user by making simple tasks more cumbersome and draining, requiring them to expend considerable mental energy to carefully control movements—and leading to herky-jerky robotic responses if they do not.
Along these lines, a recently published article in the journal Applied Ergonomics went so far as to claim that exoskeletons can negate the potential bodily benefits by placing excess burden on the brain. Exoskeletons designed to reduce lower back pain may actually compete with mental resources at work, canceling out the benefits of wearing them, the new study indicates. “It’s almost like dancing with a really bad partner,” said senior author William Marras in a statement. Marras is a professor of integrated systems engineering and director of the Ohio State University Spine Research Institute.
A zero-sum brain straining game
In the study led by Marras, the researchers had participants suit up in a Laevo exoskeleton designed to help control posture and motion during lifting to protect the lower back and reduce the possibility of injury. Upon attaching the exoskeleton to the user’s chest and legs, the participants then repeatedly lifted a medicine ball in two 30-minutes sessions.
“You’ve got to use exoskeletons with some intelligence and some understanding of what the job entails.”
The Texas A&M and Ohio State University researchers used infrared sensors to evaluate the participants’ brain activity and measured the force on participant’s lower backs during each session. Then, in separate sessions, they asked those same participants to perform the same medicine ball lifting, but added a mental task: subtracting 13 from a random number between 500 and 1,000 each time they lifted the ball.
Marras and company found that when the participants were simply lifting and lowering the ball, the exoskeleton slightly reduced the load on the participants’ lower backs. But when the participants had to do math in their heads while lifting and lowering the ball, those benefits disappeared. Although exoskeleton users on an assembly line may not have to do math in their heads, any kind of mental strain—like psychological stress, mental math, or instructions—could have the same effect, Marras said.
Like riding a bike
However, Boudewijn Wisse, founder and technical director of Laevo Exoskeletons, the company that made the devices used in the research, says you need both the right exoskeleton for the job and the know-how to use the gadget in question properly, practicing until the movements are perfected. Neither of these issues were adequately addressed in this study, he says.
Wisse argues that by choosing a task like asymmetrical lifting meant for an exoskeleton with a different purpose (symmetrical lifting), the article’s researchers only harnessed a small fraction of the spring energy stored in the exoskeleton. (In asymmetric lifting, there is a rotation between the start and stop position, as opposed to symmetric lifting, where the start and stop position are the same.) That, in turn, puts excess strain on the brain—so instead of making the task easier, it makes it harder. What’s more, Wisse says it can take weeks until someone can be proficient, energy-efficient, and familiar with an exoskeleton, not just the few minutes the participants had for the article’s experiments.
“Usability, comfort level, and mental load are the basis for exoskeleton development,” says Wisse. “If the exoskeleton is not easy to use, it will have zero effect. For non-electronic, purely mechanical devices, we, as an industry, try to keep the exoskeletons simple to make the adoption easy for the people doing the job.”
Laevo’s non-electronic exoskeletons give mechanical benefits much as a bike does, and they become second nature to use after just a bit of practice—as long as you’re willing to get past the element of fear, says Wisse.
Marras did concede somewhat, saying, “All exoskeletons aren’t bad, but people are messy, and everyone is different: You’ve got to use exoskeletons with some intelligence and some understanding of what the job entails.”
The ghost in the machine
Part of being human is that we are bipeds—our locomotion depends on two limbs, freeing up our arms and hands for other tasks. When you can’t walk, your independence becomes compromised, and you face the social stigma of immobility. Medical exoskeletons and other devices promise to return locomotion to people with paraplegia from spinal cord injuries, stroke, and neurological diseases like multiple sclerosis.
In the case of a person with paraplegia, Larry Jasinski, the CEO of ReWalk, a company which makes commercial bionic walking assistants, says one of the biggest barriers is trust. “Imagine that you can’t feel anything from your chest down, understanding that you’re floating in the air four feet above the ground,” he says. “If you fall, the only thing that will stop you is your hands or your head. There’s a fear element when you stand up that first time because you don’t trust [the exoskeleton].”
Jasinski adds that about 5 percent of clients that try their devices can’t get past that fear and ultimately cannot get the exoskeletons to work for them. “They just can’t get comfortable,” he says.
With exoskeletons that use a combination of sensors and software like a top-of-the-line motorcycle, ReWalk Robotics has helped people get back on their feet to where they can “chew bubble gum and walk.” Many users of ReWalk’s medical exoskeletons are happy to be walking around with family and friends, but some don’t stop there. Jasinski says dozens of users have participated in running events from five and ten kilometers to some of the biggest marathons, which are not only a physical endurance test but a mental one as well.
