Whitney’s exo is named “Austin” in his honor, and its robotic heritage extends back to BLEEX, an exoskeleton that Kazerooni began developing in 2000 with grant money from the Pentagon’s Defense Advanced Research Projects Agency (Darpa). In 2005, Kazerooni co-founded the company Berkeley Bionics to commercialize the devices pioneered in his university lab.
With the goal of developing an exoskeleton that costs close to what a powered wheelchair does, the students were forced to adopt a minimalist approach. Instead of updating earlier models by adding features, they had to strip them out. “Kaz told us, ‘Find a way to use fewer motors and still make this thing walk,’” Pillai says. She and the team employed two motors rather than the four or six motors of previous models. Instead of custom-designing every part, the team members bought some components from Sports Authority, including snowboard bindings and soccer shin guards to secure Whitney’s feet and legs, and shoulder straps from a backpack to hold the exo’s motors and batteries to his back. Reid, who was in charge of the Austin’s computer control systems, had to work with a system that had very few actuators powering joint movements or sensors reporting leg positions to the computer brain, which itself is a $60 microprocessor rather than a $500 one. “It’s been a huge adjustment to get performance out of the machine,” he says.
Seven minutes into the test, Whitney has walked only about 20 feet. The team had completely rebuilt the knees just a few days prior, a major design change equivalent to replacing the wings of the space shuttle a week before takeoff. The good news is that they’re holding firm. But now the machine’s torso framework is out of alignment. “It just doesn’t feel right,” Whitney says. “It’s pushing really hard on my lower back, and that’s causing me pain.” He takes another step, then stops, panting, head hung down over his shoulders and a bead of sweat dripping from his nose. “I can’t make it any further,” he says. “Get the chair."
McKinley and Tung fix the back-angle problem by 2 a.m. But new problems keep cropping up. On Thursday, after working flawlessly for thousands of previous steps, a bolt in the hip joint wriggles loose and locks the legs into a completely straight position. Austin has to be lifted, like a corpse frozen in rigor mortis, back to his chair. At Friday evening’s dress rehearsal, less than 24 hours before the commencement ceremony, Whitney’s black graduation gown gets pinned beneath the pads that hold him in the exo. When he tries to stand up, the tautly stretched fabric breaks one of the plates in the back. This time the Kaz Lab members are up until 3 a.m. machining a replacement.
“It’s like a game show,” McKinley says. “Like someone has written these riddles for us and we have x-amount of time to solve them.” When Whitney stands at graduation, though, the time to solve problems will have expired. If you comb YouTube for exoskeleton videos, what you’ll see are tightly edited demonstrations in clinical settings where every variable, such as the walking surface, can be controlled. Whitney, in contrast, is going to perform live and outdoors. “This will be a very transparent demonstration,” Reid says, “for better or worse.”single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.