These bionic legs are so light, paraplegics can wear them under clothing
t takes just 26 pounds of hardware to get Steven Sanchez walking again. He lost the use of his legs more than a decade ago in a BMX biking accident. Now Sanchez serves as test pilot for an innovative, lightweight exoskeleton from SuitX called Phoenix.
Unveiled on Monday, the wearable robot is the result of years of work and stands apart from bulky, heavy and extremely expensive exoskeletons, like the one a partially paralyzed man wore to make the opening kick at the 2014 World Cup.
“It felt really freeing, being able to stand up and feel my legs move around and being able to move through the hallways without people kind of afraid of a wheelchair," said the 28-year-old Sanchez, describing to Mashable the first time he used Phoenix.
The Phoenix suit is not cheap, it costs an estimated $40,000, but similar systems from companies like ReWalk cost nearly twice as much.
"The whole idea behind designing an exoskeleton is that it borrows from robotics technology. But this one is based on... the way we walk," said SuitX Founder and CEO Dr. Homayoon Kazerooni, who spoke to Mashable from a robotics competition in Dubai.
Instead of placing motors (also known as actuators) at each joint, Phoenix has just two motors at the hips, a design that cuts the weight of SuitX's exoskeleton considerably. Phoenix has just two motors at the hips, a design that cuts the weight of SuitX's exoskeleton considerably. The knees have electrically controlled tension settings that tighten when the wearer is standing up and swing freely when they're walking with the device.
"The human leg during level-ground walking doesn’t require much power at the knee and we’re using the same principles with our Phoenix,” said Dr. Kazerooni. Similarly, the exoskeletons ankle and foot section are standard foot/ankle orthotics and not powered at all. Without power in the knees and lower legs, the exoskeleton is not, however, appropriate for stair-climbing beyond a step or two. "I don’t think any exoskeleton allows for climbing stairs," noted Dr. Kazerooni.
SuitX's Phoenix is fully customizable. It comes in a modular design and, according to Dr. Kazerooni, is adjustable for all kinds of weights, heights and leg sizes. And while some exoskeletons are controlled by thought, Phoenix keeps things simple and puts the controllers, literally, in the hands of the wearer. It comes with two crutches, one of which includes buttons for "Go or No Go" and "Sit" or "Standup." Pressing those buttons sends messages to the hip actuators, which also control knee tension. The wearer can press forward for each step or use a continuous walk mode.
Because it's so lightweight and adjustable, wearers can put the Phoenix exoskeleton on without assistance. Sanchez, who has been testing Phoenix for almost four years, explained that he dons it in 10-15 minutes, with most of the time devoted to cinching down and securing several straps. "15 minutes is taking your sweet, sweet time. I've gotten ready in less than five minutes," Sanchez said, laughing.
Physical therapists can use a tablet-based app for calibration and gait adjustment. Typically, it's done only once.
A paraplegic wearing Phoenix can walk up to 1.1 mph (running is out of the question) for up to four hours on a charge. Sanchez said he wears the exoskeleton as often as a few hours a day, though it's more typical for him to put it on once a week.
Dr. Kazerooni believes his design, which he's been working on for five years, is "very robust and low-cost." It could also be quite stylish. “You know, they can actually wear this under their clothing,” said Dr. Kazerooni.
Sanchez, who has yet to wear the suit under his clothes, has no illusions about SuitX's Phoenix replacing the wheelchair anytime soon, but he does see a powerful use case for it right now. “This device gets me up and standing [to a height of almost 6 feet] and relieves pressure on my body, especially in my buttocks area. I deal with a lot of pressure sores."
He also explained that he can still get around far more quickly with a wheelchair — at least for now. "That is my goal, pushing SuitX making it one day — this suit — able to run."