Popular Mechanics (South Africa)
Athletes + Engineers = Miracles
THE FUTURISTIC TECH AND HUMAN INGENUITY THAT’S REDEFINING WHAT IT MEANS TO BE PARALYSED.
T
ITHE MORNING OF the powered exoskeleton finals at the 2016 Cybathlon opened on a less-than-promising note.
Mark Daniel, a 26-year-old former welder who’d been paralysed from the waist down in a car accident at 18, was rushing down a ramp at the venue when his wheelchair caught on a post. He took a hard tumble out of his chair and on to the pavement. This alarmed his teammates, a group of six engineers and technicians from the Florida Institute for Human and Machine Cognition. They’d been working 12-hour days for months, designing, assembling, and refining the robotic exoskeleton suit for which Daniel served as the lone pilot. They had no Plan B. Given the public and media spotlight focused on the Cybathlon, careers could rise or fall depending on Daniel’s performance.
All week in Zurich, Switzerland, it had been ‘Go slow, Mark. Take it easy, Mark’. He understood the concern, but was determined to make the most of his first trip abroad. Before this, the Floridian hadn’t done much travelling beyond Tallahassee.
On their first night in town, before anybody went to bed, Daniel’s teammates had unpacked and assembled the exoskeleton – 30-plus kilograms of aluminium-alloy frame, compact DC motors, sophisticated software, and lithium-battery-powered actuators. Daniel donned the suit, and the engineers asked him to walk down the hallway to test it. Instead, he made a beeline for the elevator, rode down to the lobby, and high-stepped through the bar. The next day, in his wheelchair, Daniel rolled out to see the city.
Now, after the tumble at the venue, team members fluttered around him nervously, but he was fine, he was okay, and now it was time. Daniel was in the arena, lining up for the final. The six-challenge, 40-metre-long courses were laid out in adjacent paths, allowing spectators to follow the action. His opponent was a man from Germany piloting a commercially made exoskeleton he’d used for years; Daniel had trained on the IHMC device for just eight weeks.
Organised and hosted by ETH Zürich, an elite Swiss science and technology university, the Cybathlon showcases individuals with significant physical disabilities competing in races that simulate everyday tasks. It shines a spotlight on the high-tech prosthetic devices designed by the world’s leading research groups that enable them to compete.
Each event presents a fascinating dance between human and machine: the energy of the cyclists blasting around the track in the functional electrical stimulation event; the intricate play of contestants buttering slices of bread in the powered arm prosthesis competition; the bull-rush charge of the powered wheelchair race.
But the powered exoskeleton race, a combined athletic and engineering spectacle in which people who are paralysed are empowered to walk, recalls the Biblical miracle at the pool of Bethesda. Strapped into his suit, Daniel stood for what was arguably the Cybathlon’s marquee event.
He clicked the button on the control panel of his right crutch, which sent a walk command through the software in the computer in his exoskeleton’s backpack to motors housed in the actuators encasing his leg joints. Daniel stepped to the starting line. He knew that he carried a flag not just for his teammates, but for a burgeoning community of the disabled: In the US alone, an estimated 291 000 people are living with spinal-cord injuries. Instead of causing him to freeze up, the pressure broke something open.
‘Suddenly, I felt crystal-clear inside my head,’ he says. ‘The stands, the fans hollering, the guy in the exo next to me – I didn’t see or hear any of that. I was in a bubble. All I saw was the lane in front of me’
t’s November 2019, and engineers at the IHMC robotics lab in Pensacola, Florida, are gearing up for their second shot at the powered exoskeleton race when the Cybathlon returns in November 2020 (like the Olympics, it’s held every four years). (Editor’s note: The event was due to be held in Zurich in September 2020, but the plan was adjusted because of the global pandemic. This issue went to print prior to the event taking place.)
Their new, upgraded exoskeleton (dubbed ‘Quix’) is beginning to come together. At the daily 9:30 am staff meeting, Cybathlon team leader and senior scientist Peter Neuhaus has his game face on.
A video of the exo race at Cybathlon 2016 plays in a loop on the lab’s overhead monitors. It shows Mark Daniel manoeuvring the suit gingerly as he ascends and descends a ramp, opens and closes a door, and negotiates a slalom line. Daniel will return as the team’s pilot at Cybathlon 2020.
Serving as a template for the 2020 exoskeleton, the suit Daniel wore at the 2016 event sits in the middle of the lab, perched jauntily on an IKEA sofa. With its six-foot-tall humanoid shape, articulated hip, knee, and ankle joints, and mechanical ‘feet’ set flush on the floor, the device looks like it’s about to stand and walk on its own, a feat that, with a few tweaks, lies well within its power. Lead software and controls engineer Brandon Peterson explains that the software and mechanics in the exo are similar to what’s used in IHMC’s humanoid robots.
IHMC’S EXO
Electronics housing [A]
contains the batteries, power distribution board,
and main computer.
Linear linkage
actuators create hip adduction/abduction [B] and hip flexion/extension
[C], flexion/extension at the knee [D], and ankle plantar flexion/ dorsiflexion [E] to allow for a combination of movements in the sagittal and frontal planes. (See diagram
below for a detailed look at the actuators.)
Pressure-sensing
footpads [F] read centre-of-pressure data used to help track phases of the gait cycle and provide balance feedback to the pilot.
Supportive cuffs
secure the pilot’s legs to a device at the thigh [G]
and shin [H].
‘Mark directs the exoskeleton, but he’s actually sort of riding the device,’ Peterson says. ‘The exo weighs about 35 kg, but the user doesn’t feel like they’re carrying that extra weight. Like a car or motorcycle, the exo is grounded and supports its own weight. Mark is along for the ride, but still relies on his crutches for balance.’
Peterson is designing one of the key upgrades for the suit that Daniel will wear for the next competition: sensors embedded in the soles of the exo’s feet that send pressure data to the computer housed in the suit’s backpack. The computer then transmits vibrations to pads in Daniel’s vest, alerting him if he’s off-balance and ensuring that he’s in a safe position to take another step. ‘Ablebodied people do that naturally, using proprioception in the lower body to gain an understanding of their joint positions without having to look down at their legs,’ Peterson says. ‘Mark can’t do that. He has no sensory feedback in his legs, and the messages to and from his brain stop at the break in his spinal cord.’
There will be other updates as well: The team has added two actuators that will allow Daniel to move side to side without having to pivot the entire suit. They’ve also shifted the transmission system in the DC motors from a harmonic drive, whose high gear ratio produces higher friction, to a ball-screw linkage system that reduces friction. New copper tubing will drain heat from the actuators. The challenge is to make everything as cool, small, lightweight, and userfriendly as possible.
Peterson pauses, running his hand along the blue aluminiumanodyne actuator machined to match the length of Daniel’s right thigh. ‘Programming balance in an autonomous humanoid robot is relatively easy,’ he says. ‘Achieving autonomous balance control on a device to which a human is attached is another story. When off-balance, the exo will make a correction based on the software algorithm and the user will instinctively correct with their crutches. The two actions can end up fighting each other, resulting in a dangerous tug-of-war between the robot and user.’
So having a human being strapped into in an exoskeleton makes the job of balancing a lot harder. But of course, the human being is the whole point.
Mark Daniel was five years old when he started riding dirt bikes through the pine woods around Pensacola. He was 15 when his mom and dad insisted he quit after a crash ruptured his spleen and nearly killed him. Daniel redirected his restless energy into cocaine and smallscale street crime. He was 17 when his parents confronted him with a choice: continue on a path of self-destruction or deal with his addiction by enrolling in the Job Corps. Daniel picked Job Corps.
He arrived at the Muhlenberg Job Corps Center in Greenville, Kentucky, strung out, weighing 60 kg, and not far from death. He sweated out the drug cravings, got certified in diesel maintenance,
and learned to weld. He ran 10 miles a day, ate upwards of 6 000 daily calories, lifted weights, and put on 20 kg of muscle. Nine months later, Daniel returned to Pensacola and dived into work.
Then came October 19, 2007. A Friday night. Daniel had been working seven days a week, 10 to 14 hours a day, making good money with no time to spend it. He was just 18, but a plan was taking shape. Work for 10 years, keep saving money. Buy a place in the country (cash, no mortgage) with space for his tools, vehicles, and maybe a few animals. He would start his own contracting company, be his own boss.
That Friday night, he clocked off the job – steel fabrication for a new US Navy storage facility – around 7:30 pm, after working 93 hours in eight days. On the way home, he stopped by a friend’s house. ‘Before I know it, I’m dead asleep,’ Daniel recalls.
Two hours later, he awoke with a jolt. His friend urged him to spend the night on the couch, but Daniel was riding that work wheel – the iron adherence to routine so crucial for people in recovery. He decided to make the 32 km trip home to sleep in his own bed.
Daniel headed out on a dark two-lane road. He nodded off and brushed a guard rail. ‘I cranked up the radio and reminded myself that home was less than 10 miles away,’ he says. ‘That’s the last thing I remember.’
Hours later, he woke up in the ICU, paralysed from the waist down. ‘My spinal cord was broken and one lung crushed from being smashed against the centre console of my truck as it flipped seven times,’ he says. ‘Doc tells me I coded once in the helicopter and again on the