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Driving Robotic Rehab

POSTED 12/18/2017

 | By: Tanya M. Anandan, Contributing Editor

Rehabilitation robotics, although still an emerging field, is getting a shot of adrenaline because of sheer necessity. Mainly to keep pace with the world’s aging population.

By 2050, the global population of people aged 65 and older is projected to double. Incidences of disease and injury associated with aging, including Parkinson’s disease, traumatic brain injury and stroke, will follow suit. Sobering, yes. But hope endures.

Our brains have remarkable plasticity. Through repetitive movement, we can reconnect vital neurons and relearn motor control. Robotic rehabilitation is helping us set new therapeutic goals, augment the efforts of physiotherapists, motivate patients, and qualify results. Robotic rehab is forcing us to reevaluate what we thought was possible for recovery and renewal.

Robotic gait therapy facilitates patients’ leg movements and mirrors a natural walking gait for faster rehabilitation and recovery. (Courtesy of maxon motor, copyright Hocoma)Robotic devices such as Toyota’s new Welwalk system and the Hocoma Lokomat® (shown) provide robot-assisted gait therapy for patients with walking disabilities caused by neurological, muscular, or bone-related disorders. These robotic exoskeletons help physiotherapists provide more intense and consistent therapies for severely impaired patients.

With the robot handling the heavy lifting, physiotherapists are free to focus on other aspects of therapy and fine-tune sessions to each individual. Robot-assisted therapy also reduces physical strain on therapists, allows therapists to tend to more patients, increases therapy duration and intensity, and provides reproducible results.

Mighty Motors
RIA member maxon precision motors makes many of the motors you will find in today’s robotic rehabilitation devices, including the Lokomat robot. Only 40 millimeters in diameter, each of the maxon RE 40 motors in the robot’s knees provides 150 watts of power.

Established in 1961, maxon’s world headquarters is in Sachseln, Switzerland. maxon is a private company owned by the family of Dr. Karl-Walter Braun. Yes, that Braun, the name behind Braun electric shavers. 

Like many Swiss companies, maxon has a strong engineering base and relies heavily on its country’s deep talent pool of engineers. The Swiss are proficient at making things small and precise, like their legendary watch technology.

Pete van Beek, Midwest Senior Sales Engineer, has been with maxon for 24 years. He says “extreme power density is the name of the game” in motor technology, especially for rehabilitation robotics where many of these devices are attached to the body. This means the motor must pack a lot of power into a small package. 

In addition to extreme power density, maxon’s motors are known for their lightweight design, high efficiency for longer battery life, all metal construction to hold up to vibration and shock, low inductance coil design for longer brush life, large speed range capability, and fast acceleration/deceleration. 

The company routinely makes custom modifications to their motors to tailor-fit specific applications. Industry, universities, research institutes, and startups often turn to maxon for its extensive experience in solving drive technology challenges.

Robotic exoskeleton helps patients with mobility impairments to stand, walk and perform rehabilitative exercises. (Courtesy of maxon motor, copyright Rex Bionics Ltd.)At its most basic level, a motor consists of magnets and coiled copper wires called windings. van Beek says maxon has always strived to use the highest flux density magnets to get the most torque out of its motors. The company’s engineers have found creative ways to pack more turns into their windings and transfer heat out and away from the motor. Ultimately, the motor’s ability to dissipate heat and run at higher operating temperatures dictates how much power you can obtain from the motor.

“In an exoskeleton, you’re really overdriving these motors. You’re just hammering them,” says van Beek. “Getting rid of the heat is critical, because that allows you to get more torque and more performance out of your motor.”

maxon makes two types of DC motors, brushed and brushless. 

Powerful but Small
The company’s brushed and cylinder brushless motors are all centered on a patented ironless winding that provides efficiencies up to and exceeding 90 percent, according to van Beek. That could be the difference between an exoskeleton with a battery that lasts an hour versus two to three hours.

The ReWalk exoskeleton has four maxon motors inside. The motors perform the movement of the hips and knees. In this case, brushed DC motors and gearheads were chosen for their power density, efficiency level, and robust design. The gearbox contains ceramic components to extend the service life of the assembly, thus making it reliable, low maintenance and powerful, yet small.

Maxon motors are also inside the Rex Bionics exoskeleton (shown) used for robotic rehabilitation. REX® enables patients with mobility impairments to stand, walk and exercise on their own or with minimal assistance. Ten maxon motors provide smooth limb movements. Watch this wheelchair user put REX through its paces.

Recumbent trike provides therapeutic benefits to patients with spinal cord disorders. (Courtesy of maxon motor)At the Institute for Rehabilitation and Performance Technology (IRPT) at the Bern University of Applied Sciences in Switzerland, researchers study the effects of cycling using recumbent trikes with robotic technology to help restore lost motor functions of patients with spinal cord lesions. A maxon motor keeps the cycler’s legs in motion.

You will find maxon motors in all kinds of rehabilitation and personal-assist robots, everything from exoskeletons and robotic physiotherapy devices for upper body, arm and hand rehabilitation, to prosthetics, and even a robotic stair-climbing wheelchair. But these are not the types of motors used in your standard industrial robots. maxon motors are very small, ranging from 4 to 65 millimeters in diameter (0.5 to 480 watts).

They are however just the right size for one industrial arm. In 2016, Mecademic introduced the world’s smallest industrial robot. You can hold the Meca500 robot in the palm of your hand. This six-axis arm weighs only 5 kilograms, but with the help of maxon motors it achieves repeatability of 0.005 millimeters. 

maxon motors were also on board the first Mars rover, when it landed on the red planet in 1997, and have driven every Mars mission since. maxon motors drive the wheels as well as the probes that collect samples from the planet’s surface.

Adaptive Orthotics for Vets
Back on Earth, university researchers are developing novel approaches for using robotics to help our wounded veterans live more active lifestyles. Dr. Michael Yip, Assistant Professor of Electrical and Computer Engineering, and Director of the Advanced Robotics and Controls Lab (ARCLab), at the University of California San Diego is working with the U.S. Navy to create robotic orthotics and prosthetics that adjust to the wearer’s activities.

“This category of orthotics and prosthetics is new in the sense that we’re not only looking to recover functionality on a very basic level, but we want to reach high performance functionality for high-impact activities such as running, hiking and jumping, the types of sport and exercises that you would expect a young adult to participate in,” says Yip.

The idea is that with robotics you’re no longer limited to a rigid orthotic or prosthetic. You can use robotics to change the behavior of the device to adapt to the activity. For example, you can change the shape or stiffness of the prosthetic.

“When you see some of the Paralympic track runners, the prosthetics that they use on the track are a very different shape, which provides different types of stiffness that are conducive for running,” explains Yip. “They are generally not comfortable or good for your posture when standing or walking. 

“Right now, they have to physically carry around different prosthetics and switch them in an out for different activities,” he continues. “Being able to vary the shape and the stiffness of the prosthetic, or orthotic, can really help address all the different types of activities somebody might go through during a daily routine.”

Professor Yip can’t divulge many details at this stage of development, but says the orthotic would be a sort of exoskeleton that might include a robotic frame around the ankle and knee. The prosthetic would be a robotic limb that is programmed to adjust its shape and stiffness according to the user’s input. The person wearing the prosthetic or orthotic has control. 

“If you need to climb stairs, you just tune it so that it’s stair-ready,” says Yip. “Then when you’re done climbing the stairs, you set it back to a standard level.”

Yip’s team is currently working on an orthotic device for veterans at the Navy Medical Center in Balboa Park. By having a device that’s able to adapt to different activities, you reduce loading on the joints and subsequently reduce instances of arthritis often caused by traditional orthotics or prosthetics that are designed for only one activity.

Advanced Artificial Muscles
ARCLab is also working on artificial muscles as an innovative and low-cost actuator for robots. The key element of their artificial muscles is conductive sewing thread, the kind often used for textiles that contain electronics like light-up T-shirts. 

The synthetic muscle fibers are made of silver-coated nylon sewing threads that are spun into a tightly coiled structure. When voltage is applied to the fibers, they heat up and contract. As they cool, they relax to their original length. By braiding multiple coiled fibers together, Yip’s team has created a stronger “muscle” that can lift a heavier load. Yip explains why this is significant.

University researchers built a robotic glove for hand rehabilitation using artificial muscles made from conductive sewing thread. (Courtesy of Jacobs School of Engineering, UC San Diego)“We’ve twisted the threads, which amplifies the contraction to the point where you’re achieving up to 30 percent contraction and that’s approaching the range of human muscles. If you look at traditional artificial muscles, they used to be metal alloys that you heat up and they would contract maybe 1 or 2 percent. The best human muscle is about 40 percent contraction, so we’re very much within range of realistic biological contractions.”

Before Yip joined UC San Diego, he worked at Walt Disney Imagineering, the R&D arm and creative force behind Disney’s theme parks and attractions. At Disney Research, he developed the artificial muscle technology to make life-like animatronic hands and arms. Now at UC, Yip and his team work on amplifying the force and contraction of these artificial muscles to create robotic devices for rehabilitation, augmentation and limb replacement.

“We’re looking at using these muscles for rehabilitation of the hand, using it for posture control, for a potential actuator for orthotics and prosthetics, and in general, for biomimetic robots, or robots that behave like natural animals,” says Yip, whose research team has already built a glove for hand rehabilitation (shown).

There are also implications for exoskeletons. A single thread weighs less than a gram. Even when bundled, the weight is negligible. It becomes a lightweight actuator that can apply a significant amount of additional force to help lift a load. And because it’s a thread or rope, it can be weaved into textiles.

Yip says there’s been significant interest from industry in these actuators: “We’re talking about a general-purpose actuator that behaves differently than anything before it. It’s inherently compliant and lightweight, so that makes it safe. You can push against it, and it has spring-like behavior. It’s not a rigid, stiff joint.

“All of these robots these days use motors,” he continues. “You’re using technology that’s designed to have a rotating spindle which spins at high speeds, and then you slap on gears and heavy-duty transmissions to create linear motion. This actuator natively generates linear motion. There’s something really nice about how clean it generates linear motion like a normal muscle, something you don’t see with traditional motors.”

Yip’s research team is also in discussions with chemists at the Jet Propulsion Laboratory and the California Institute of Technology to develop a new mechanism for actuating the artificial muscles that is more energy-efficient. 

“This is not the final version of these muscles in any sense,” says Yip. “We now have the properties, though, to really demonstrate some great robotics with them.”

Meanwhile, other developments in artificial muscle technology, soft robotics, and collaborative and wearable robotics are bringing new life to rehabilitation and wellness.

Researchers from the University of Texas at Austin are developing Harmony and Maestro, two rehabilitation robots for upper-body extremity therapy.

KUKA’s LBR Med robot is handling the heavy lifting for Robert®, a robotic device for rehabilitating bedridden patients.

Soft roboticists at Harvard have designed a soft, wearable robotic exosuit to help stroke victims walk again.

Robotic Apparel with Muscle  
A new startup aims to flip the rehabilitation robotics market on its head and bring a wearable robotic solution direct to consumers. Seismic has created a new category of wearable robotics it calls Powered ClothingTM. This lightweight, connected apparel is designed to add “intelligent wearable strength” to muscles and joints.

“If you look at the history of rehabilitation robotics, the products are typically bigger, bulky, expensive devices focused on the acute care clinical experience,” says Seismic CEO Rich Mahoney. “These devices sell for tens and hundreds of thousands of dollars to large institutions. They never make it into the home, and they never make it into consumer products. I think there is a lot of opportunity for robotics to benefit people, but the current paths have led to a limited number of devices with a limited application space.”

Wearable robotic suit will provide core support and powered assistance for everyday activities, particularly for the aging population. (Courtesy of Seismic)Mahoney says hardware-intensive devices such as exoskeletons are neither practical nor affordable for everyday consumers. Seismic’s robotic suit is instead focused on general wellness. It’s designed to be worn discreetly under clothing, to provide wearable strength during any activity that requires core support, such as sitting and standing for long periods of time, or getting up from a chair.

The company is initially focusing on baby boomers, noting that within 10 years, people aged 65 and older will outnumber young children for the first time in history. It’s no coincidence that the startup’s primary investor is Tokyo-based Global Brain. Support for products and services geared toward older adults is already more advanced in Japan, but the country will face significant challenges ahead as its 65-and-older population is projected to increase to 30 percent by 2025.

Seismic’s robotic apparel is based on patented technology originally developed at nonprofit research center SRI International as part of a DARPA-funded program called Warrior Web. The DARPA wearable robotics program was created to reduce soldiers’ fatigue and risk of injury when they carry heavy loads. The wearable technology was designed to be lightweight and body conforming — an alternative to big, bulky exoskeletons.

Soft, but Strong to the Core 
What makes Seismic’s robotic suit unique are the electromechanical artificial muscles embedded into the fabric. The “muscles” are powered by small motors connected to tendon-like filaments. When these “tendons” contract, they pull on strategically located positions on the body, creating an external force that acts like human muscle. 

Robotic suit has integrated artificial muscles and sensors that detect wearer’s movements and provide strength and support for the hips and lower back when needed. (Courtesy of Seismic)“We have a harnessing solution that’s textile-based, that comfortably harnesses the muscle to the body,” explains Mahoney. “We don’t use an exoskeleton or a frame. We use the human body itself as the frame.”

Seismic’s artificial muscles are combined with innovations in 3D-engineered knit textiles, tiny mobility tracking sensors, and on-board computing to create a product that looks and feels like apparel, but functions more like an extension of the human body.

“We are designing it to act in a very synergistic way with the wearer,” says Mahoney, “so that the sensors are able to detect movement, and depending on the setting, will automatically add strength to the person while they are doing different activities.”

The robotic suit is worn as an undergarment. The artificial muscles are integrated into the thigh and lower lumbar regions of the suit to support a person’s hips and lower back. The force applied varies and is programmed depending on the wearer’s height and weight, physical features, and the amount of power-assist desired.

“We are designing it as clothing you can wear all day long. You shouldn’t be aware of it,” says Mahoney. “Some of our best internal testing is when the system is working synergistically with the wearer and they don’t even realize that it’s moving, because it’s coordinating with them so well.”

Seismic is the rebranded company name of Superflex, the prototype exosuit developed at SRI International, where Mahoney was Executive Director of Robotics for over seven years. He was also the founding President of Silicon Valley Robotics and formerly U.S. General Manager of Motorika, which makes robot-assisted rehabilitation products. 

The primary focus of Mahoney’s 25-plus year career has been rehabilitation robotics and assistive technology. In 2016, he decided it was time to get back to early-stage product development, so he licensed the technology from SRI, bid his adieu, and brought with him three colleagues from the lab. The current team comprises leaders in textile innovation, robotics, biomechanics, and artificial intelligence.

This is the first of several products that Seismic is developing with its Powered Clothing technology. The company eventually plans to bring its wearable robotics to medical rehabilitation, industrial work, athletics, gaming, and high-end apparel design.

The robotic suit has been in beta testing for the past year as the startup progresses through Series A funding. Mahoney says they are exploring partnerships with continuing care retirement communities, among other marketing avenues. Seismic’s goal is to shake up the market in 2018.

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