The majority of exoskeletons currently on the market only focus on the lower body. For one, demand is simply higher—your legs are what give you mobility, after all. Two, upper body problems are tougher to solve, because the range of motion is more complex.
“The ability to pick up a cup of coffee and moving it around is more complicated than moving your feet forward,” says professor Jacob Rosen, director of UCLA’s Bionics Lab. He specializes in working with stroke patients, who often have one healthy, mobile arm, and one that is paralyzed. The goal is to use exoskeletons to restore life to the affected arm.
“We are designed to deal with an environment that is hard to predict,” Rosen says. “That’s why we have two arms, two lungs, two kidneys.” And since we’re not starfish that can sprout backup extremities, we have to get a bit more creative in how we adapt to such situations.
The UCLA Bionics Lab is currently outfitting stroke patients with robotic arms using a technique called “mirror image.” Patients put both arms (one healthy, one paralyzed) in exoskeletal sleeves and then begin navigating a virtual reality system—for example, playing a squash game. Every time the patient moves the healthy arm, electrical signals are sent to the other sleeve, which moves the paralyzed arm in the same fashion. This could help stroke victims “relearn” how to use their upper limbs.
In another activity that also resembles physical therapy, an “artificial force field” is created. The exoskeleton will help a paralyzed arm move within a restricted space. In the game, the patient must “paint” a virtual surface, but every time the arm strays from the area that’s supposed to be painted, the robotic sleeve pushes the paralyzed arm back, replacing the need for another human to physically force the patient’s arm to move in certain ways in order to rebuild mobility.