The Ascend is a robotic knee brace on a budget

Andrew Tarantola
·Senior Editor
·5 min read

You might be surprised by how many Americans are walking around these days with synthetic joints hidden in their pants. First performed in 1968, more than three-quarters of a million people in the US opted for knee replacement surgery in 2017 alone, according to the American Association of Orthopedic Surgeons. However, many knee replacement candidates (an estimated 300,000 in 2017) simply aren’t yet ready to go under the knife — whether that’s due to health, financial, employment or other reasons — but who could still benefit from some added support from a medical device. But rather than strap yourself into a P-5000 Powered Work Loader — or even something slightly less extravagant like the Ekso NR — Bay Area startup Roam Robotics has a less intensive and expensive means of getting folks with mobility issues back on their feet. It’s called the Ascend and it’s a sub-$10k exoskeletal knee brace for everybody.

Full-body assistive devices like the NR are impressive pieces of medical machinery, to be sure. These exoskeletons can bear the weight of a full-grown adult, helping them walk and reach in ways they otherwise wouldn’t be able to. They’re also $150,000, weigh 60-plus pounds and have a top speed of about a half mile an hour, Roam Robotics founder and CEO, Tim Swift, noted to Engadget, so they’re not exactly convenient to operate. You don’t just strap one of these on at the start of your day and go about your business. However that’s exactly what the Ascend is designed to do.

“Robotics as a whole is a story of not really things that do so much,” Swift said, “but things that do so little. You have to put them in very narrow circumstances to be successful. And our real hunt was ‘how do we put these things in the real world where real people are?’”

“I knew the human good that could be developed by putting robots in people's lives and changing the way they lived them,” he continued. “We just didn't have a tool set that allowed us to be there with them.”

To achieve this, the Ascend is purpose built with low-cost, lightweight materials in mind. Overall one of these devices consists of a 2-pound brace that fits around the upper leg and knee as well as a separate 10-pound backpack which holds the system’s processor, battery and compressed air reserves used for activating the brace as the user steps. A series of cloth bladders inflate and deflate within the rigid plastic framework to help swing the lower leg back and forth.

“The first question we asked is ‘what is the cheapest way humanly possible for us to put power into an object?’,” Swift said. Turns out, that’s air. Liquid hydraulics can get messy when they leak while electromechanical activators are heavy and generate heat when in use, he explained. An electromechanical actuator on the other hand, would likely weigh close to 8 pounds at the joint, making the act of swinging the leg back and forth far more energy intensive than it would be with a lighter weight (hello, pendulum effect). “The problem is weight,” Swift said. “I could wear 10 pounds on my torso and have one pound on my foot, and they'll have the same metabolic impact on me. So your real issue is how much weight you have to put at the joint.”

“There's enormous functional benefits associated with the pneumatic system, that you really can't get through conventional hydraulics or electromechanical systems,” he continued. “If you went out and bought a leg brace that just does the control of the joint the way that our bracing does, you'd be looking at a two pound structure. We're two and a half pounds all in and that includes robotics, actuation, electronics control, sensing, the whole nine yards — so for a half pound, we've added enough robot to do 50 percent of the power of a normal human knee.”

As part of the company’s current, 80-patient pilot study, Roam researchers saw a 50 percent reduction in perceived pain while 60 percent of them reported a functional benefit [such as improving the ability to stand up or better balance while moving up and down stairs] as a result of using the device, Swift asserted, with the goal of, “restoring capabilities, helping people that are really trying to get back to the life that they were intending to live... really putting them back where they want to be.”

For Ascend users, the company estimates that a full battery charge should be sufficient to help users make it through a half-day of conventional use — basically, hiking up and down stairs as opposed to the Adirondacks. For the more robust Elevate brace, which Roam designed specifically for skiers, the battery supports up to 12 hours on the slopes and Roam’s milspec Forge exoskeleton can last between 4 and 6 hours of continued use.

roam
roam

The Ascend is not for everybody however, “for paraplegics or very severely impaired stroke patients, we're probably not a great fit right now,” Swift admitted. “A lot of those patients need not be compliantly guided towards a target, they need to be physically moved to where they need to be. And so in our current instantiation we are really targeting people who are otherwise in volitional control.” The Ascend is currently available to order as both a Medicare-covered device or direct purchase for around $7,000 when they start shipping in late summer. A sport variant designed to help skiers stay on the slopes longer without tiring and a military-spec version, dubbed the Forge, are currently in development.