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Hyundai/Kia engineers calibrate a strap-on exoskeleton developed in house.

The race to engineer robotic personal mobility

In her year-end LinkedIn post last December, GM CEO Mary Barra predicted that “2016 and beyond will be pivotal in terms of how people around the world will get from Point A to Point B…Game changers like shared mobility, autonomous driving and alternative propulsion are evolving rapidly and we [are] developing and testing new concepts and ideas that will redefine the future of personal mobility…”

Innovations in the ever-expanding category of personal mobility technology (PM) have become the norm both in and out of the auto industry in recent years. Beyond renewed focus on the bicycle, new design concepts for all kinds of novel electric vehicles continue to appear—everything from nimble quad/tricycle city cars, urban runabouts and sidewalk buggies to e-bikes, scooters and self-balancing Segways, hoverboards and even unicycles.

Concept car designers at BMW, Ford, Geely, GM, Honda, Hyundai/Kia, Renault NissanSuzuki, Toyota, VW and others have incorporated these PM vehicles—often miniaturized, foldable, or collapsible—to explore ‘dual-mode’ ways to get passengers that ‘last-mile’ home by providing ‘total mobility services.’ Navigating that critical last mile—really, only the last few hundred meters—has garnered greater attention as the world’s population ages and interest grows in improving accessibility for the elderly, paraplegics and the mobility-impaired.

But wheels, despite their mechanical efficiency, can limit access in areas where there are stairs or rough ground, and one generally needs legs to drive cars. This basic limitation is why many prototype robots such as the DARPA Challenge’s rescue-bots and Google/Boston Dynamics’ Big Dog robotic mules, the Cheetah robot sprinter and Honda's world-famous Asimo, rove around on legs.

Exoskeletons stand up

So it’s little wonder that engineers at some forty-plus companies and research organizations worldwide have in recent years developed strap-on legged/walking PM vehicle designs. In these powered exoskeletons the passenger actually wears a mobile robot. Although these systems bear only passing resemblance to Tony Stark’s Iron Man suit or Ellen Ripley’s Caterpillar Power Loader from the movie Alien, not only are exoskeletons starting to address the PM issues of disabled and aged people, the same articulated body booster technology offers help to industrial workers, nurses, firefighters, soldiers and others who regularly bear loads or move rapidly over distances.

Since 2014, for example, researchers at Hyundai/Kia have been developing a prototype wearable exoskeleton that assists people with mobility problems. This system, which includes sensors, drive motors, transmissions, batteries and a computer controller, can sense the wearer’s intention to move and either supplement or boost muscle power.

Company engineers have completed four strap-on modules including a knee flexor, hip joint-flexor, a combination of both, as well as a related device for medical treatment that is now under clinical testing. See


But high costs and weight still stand in the way of wider use of the nascent technology. Medical exoskeletons produced by companies such as Japan’s Cyberdyne and Israel’s Rewalk Robotics can cost more than $80,000 and can weigh in at over 20 kg (44 lb).

Bare-bones exoskeleton

Meanwhile, Homayoon Kazerooni, professor of mechanical engineering at the University of California, Berkeley, and co-founder of Richmond, CA-based Ekso Bionics, the current exoskeleton market leader, has been working to make the technology more affordable. For the last five years, the robotics pioneer and his colleagues at his latest start-up firm, SuitX in Berkeley, have come up with a stripped-down 12-kg (27-lb) medical exoskeleton called Phoenix that enables people with mobility disorders to rise up from their wheelchairs and walk, even get into a car and drive it away.

Still, the no-frills Phoenix system costs about $30,000, so Kazerooni’s team is trying to reduce cost and weight. “Rather than making the Ferrari of exoskeletons, we’re trying to make the Honda sedan,” Kazerooni told Automotive Engineering at the recent RoboUniverse New York conference at the Javits Center.

“We want a system that can do the basic maneuvers at an affordable price—a couple of thousand dollars,” he said. Their current aim is to use the device to train the muscles of cerebral palsy sufferers—to exercise them to postpone further deterioration.

“Our approach is simplification; to build a fully functioning exoskeleton with the minimum amount of structure and the maximum intelligence to cut weight, complexity and manufacturing costs,” Kazerooni stated. “Phoenix, for instance, has no sensors in the feet, no actuators in the knee module and features the smallest possible computer.”

Phoenix’ design differs from those of most other systems in that it has electric motors only in the hip module whereas others also have them in the knees to lift and move the lower legs as the user strides ahead. “The knees have no actuation,” he explained. “All movement is created by the hip actuators and a special knee-joint geometry, which together swing the lower legs forward.”

During each step, one of Phoenix’ hip motors lifts a leg while an unpowered knee mechanism rotates the lower leg forward in a natural fashion. The knee mechanism, controlled by sensors that measure tilt, angle and acceleration, then stiffens up when they sense the foot meeting the ground so the leg can take the body weight.

The key is that sophisticated software ensures that all these movements occur at just the right moment, in just the right way, since any error could cause a fall.

“The computer control is pretty intelligent,” Kazerooni noted. “It recognizes the user’s intent, provides self-stabilization and offers a rich user interface as well—gait analysis, operational parameter tuning and so forth.”

The Phoenix unit, which offers 4 hours of continuous battery life and double that for intermittent use, is now undergoing U.S. Food and Drug Administration tests. SuitX hopes to place the systems—one for adults, another for children—on the market by year’s end.

Auto worker assistants

Kazerooni added that SuitX also makes hip-, knee-, shoulder-support products for industrial workers, in particular, auto plant employees. The company’s MAX (modular agile exoskeleton) unit “minimizes the risk of injury among factory workers, who often repeatedly take and maintain the ‘wrong’ postures during shoulder-, lower back- or leg-intensive job tasks such as loading trucks, welding, assembly, etc.”

The MAX modules provide powered assistance to hold whatever position the worker chooses. “The system minimizes injuries, boosts productivity, reduces fatigue—generally improves the worker’s quality of life,” he said.

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