A portable exosuit assists both walking and running

The team’s portable exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which uses an algorithm that robustly predicts transitions between walking and running gaits. Credit: Wyss Institute at Harvard University

A versatile, portable exosuit that assists both walking and running highlights the potential for lightweight and non-restrictive wearable robots outside the lab

Between walking at a leisurely pace and running for your life, human gaits can cover a wide range of speeds. Typically, we choose the gait that allows us to consume the least amount of energy at a given speed. For example, at low speeds, the metabolic rate of walking is lower than that of running in a slow jog; vice versa at high speeds, the metabolic cost of running is lower than that of speed walking.

Researchers in academic and industry labs have previously developed robotic devices for rehabilitation and other areas of life that can either assist walking or running, but no untethered portable device could efficiently do both. Assisting walking and running with a single device is challenging because of the fundamentally different biomechanics of the two gaits. However, both gaits have in common an extension of the hip joint, which starts around the time when the foot comes in contact with the ground and requires considerable energy for propelling the body forward.

As reported today in Science, a team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS), and the University of Nebraska Omaha now has developed a portable exosuit that assists with gait-specific hip extension during both walking and running. Their lightweight exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which is controlled by an algorithm that can robustly detect the transition from walking to running and vice versa.

The team first showed that the exosuit worn by users in treadmill-based indoor tests, on average, reduced their metabolic costs of walking by 9.3% and of running by 4% compared to when they were walking and running without the device. “We were excited to see that the device also performed well during uphill walking, at different running speeds and during overground testing outside, which showed the versatility of the system,” said Conor Walsh, Ph.D., who led the study. Walsh is a Core Faculty member of the Wyss Institute, the Gordon McKay Professor of Engineering and Applied Sciences at SEAS, and Founder of the Harvard Biodesign Lab. “While the metabolic reductions we found are modest, our study demonstrates that it is possible to have a portable wearable robot assist more than just a single activity, helping to pave the way for these systems to become ubiquitous in our lives,” said Walsh.

The hip exosuit was developed as part of the Defense Advanced Research Projects Agency (DARPA)’s former Warrior Web program and is the culmination of years of research and optimization of the soft exosuit technology by the team. A previous multi-joint exosuit developed by the team could assist both the hip and ankle during walking, and a medical version of the exosuit aimed at improving gait rehabilitation for stroke survivors is now commercially available in the US and Europe, via a collaboration with ReWalk Robotics.

The team’s most recent hip-assisting exosuit is designed to be simpler and lighter weight compared to their past multi-joint exosuit. It assists the wearer via a cable actuation system. The actuation cables apply a tensile force between the waist belt and thigh wraps to generate an external extension torque at the hip joint that works in concert with the gluteal muscles. The device weighs 5kg in total with more than 90% of its weight located close to the body’s center of mass. “This approach to concentrating the weight, combined with the flexible apparel interface, minimizes the energetic burden and movement restriction to the wearer,” said co-first-author Jinsoo Kim, a SEAS graduate student in Walsh’s group. “This is important for walking, but even more so for running as the limbs move back and forth much faster.” Kim shared the first-authorship with Giuk Lee, Ph.D., a former postdoctoral fellow on Walsh’s team and now Assistant Professor at Chung-Ang University in Seoul, South Korea.

A major challenge the team had to solve was that the exosuit needed to be able to distinguish between walking and running gaits and change its actuation profiles accordingly with the right amount of assistance provided at the right time of the gait cycle.

To explain the different kinetics during the gait cycles, biomechanists often compare walking to the motions of an inverted pendulum and running to the motions of a spring-mass system. During walking, the body’s center of mass moves upward after heel-strike, then reaches maximum height at the middle of the stance phase to descend towards the end of the stance phase. In running, the movement of the center of mass is opposite. It descends towards a minimum height at the middle of the stance phase and then moves upward towards push-off.

“We took advantage of these biomechanical insights to develop our biologically inspired gait classification algorithm that can robustly and reliably detect a transition from one gait to the other by monitoring the acceleration of an individual’s center of mass with sensors that are attached to the body,” said co-corresponding author Philippe Malcolm, Ph.D., Assistant Professor at University of Nebraska Omaha. “Once a gait transition is detected, the exosuit automatically adjusts the timing of its actuation profile to assist the other gait, as we demonstrated by its ability to reduce metabolic oxygen consumption in wearers.”

In ongoing work, the team is focused on optimizing all aspects of the technology, including further reducing weight, individualizing assistance and improving ease of use. “It is very satisfying to see how far our approach has come,” said Walsh, “and we are excited to continue to apply it to a range of applications, including assisting those with gait impairments, industry workers at risk of injury performing physically strenuous tasks, or recreational weekend warriors.”

“This breakthrough study coming out of the Wyss Institute’s Bioinspired Soft Robotics platform gives us a glimpse into a future where wearable robotic devices can improve the lives of the healthy, as well as serve those with injuries or in need of rehabilitation,” said Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School, the Vascular Biology Program at Boston Children’s Hospital, and Professor of Bioengineering at SEAS.

Learn more: Suit up with a robot to walk AND run more easily

 

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First inexpensive ankle exoskeleton that could be worn under clothes without restricting motion

The new ankle exoskeleton design integrates into the shoe and under clothing.

A new lightweight, low-profile and inexpensive ankle exoskeleton could be widely used among elderly people, those with impaired lower-leg muscle strength and workers whose jobs require substantial walking or running.

Developed by Vanderbilt mechanical engineers, the device is believed to be the first ankle exoskeleton that could be worn under clothes without restricting motion. It does not require additional components such as batteries or actuators carried on the back or waist.

The study, published online by IEEE Transactions on Neural Systems & Rehabilitation Engineering, builds on a successful and widely cited ankle exoskeleton concept from other researchers in 2015.

“We’ve shown how an unpowered ankle exoskeleton could be redesigned to fit under clothing and inside/under shoes so it more seamlessly integrates into daily life,” said Matt Yandell, a mechanical engineering Ph.D. student and lead author of the study.

In a significant design advancement, the team invented an unpowered friction clutch mechanism that fits under the foot or shoe and is no thicker than a typical shoe insole. The complete device, which includes a soft shank sleeve and assistive spring, weighs just over one pound.

The unpowered ankle exoskeleton costs less than $100 to fabricate, without factoring in optimized design for manufacturing and economies of scale.

“Our design is lightweight, low profile, quiet, uses no motor or batteries, it is low cost to manufacture, and naturally adapts to different walking speeds to assist the ankle muscles,” said Karl Zelik, assistant professor of mechanical engineering and senior author on the study.

Zelik will be presenting this work next week at the Wearable Robotics Association Conference in Phoenix, Arizona.

The potential applications are broad, from helping aging people stay active to assisting recreational walkers, hikers or runners, he said.

“It could also help reduce fatigue in occupations that involve lots of walking, such as postal and warehouse workers, and soldiers in the field,” Zelik said.

Learn more: New low-profile ankle exoskeleton fits under clothes for potential broad adoption

 

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New AI algorithms could allow robots to learn to move by themselves, imitating animals

ONE OF THE VALERO LAB’S ROBOTS AND THE NEW ROBOTIC LIMB IN ACTION. PHOTO/MATTHEW LIN

For a newborn giraffe or wildebeest, being born can be a perilous introduction to the world—predators lie in wait for an opportunity to make a meal of the herd’s weakest member. This is why many species have evolved ways for their juveniles to find their footing within minutes of birth.

It’s an astonishing evolutionary feat that has long inspired biologists and roboticists. Now a team of USC researchers at the USC Viterbi School of Engineering believe they have become the first to create an AI-controlled robotic limb driven by animal-like tendons that can be tripped up and then recover within the time of the next footfall, a task for which the robot was never explicitly programmed to do.

Francisco J. Valero-Cuevas, a professor of Biomedical Engineering and professor of Biokinesiology & Physical Therapy at USC, in a project with USC Viterbi School of Engineering doctoral student Ali Marjaninejad and two other doctoral students—Darío Urbina-Meléndez and Brian Cohn, has developed a bio-inspired algorithm that can learn a new walking task by itself after only 5 minutes of unstructured play, and then adapt to other tasks without any additional programming.

Their article, outlined in the March cover article of Nature Machine Intelligence, opens exciting possibilities for understanding human movement and disability, creating responsive prosthetics, and robots that can interact with complex and changing environments like space exploration and search-and-rescue.

“Nowadays, it takes the equivalent of months or years of training for a robot to be ready to interact with the world, but we want to achieve the quick learning and adaptations seen in nature,” said senior author Valero-Cuevas, who also has appointments in computer scienceelectrical and computer engineeringaerospace and mechanical engineering and neuroscience at USC.

Marjaninejad, a doctoral candidate in the Department of Biomedical Engineering at USC, and the paper’s lead author, said this breakthrough is akin to the natural learning that happens in babies. Marjaninejad explains, the robot was first allowed to understand its environment in a process of free play (or what is known as ‘motor babbling’).

“These random movements of the leg allow the robot to build an internal map of its limb and its interactions with the environment,” said Marjaninejad.

The paper’s authors say that, unlike most current work, their robots learn-by-doing, and without any prior or parallel computer simulations to guide learning.

Marjaninejad also added this is particularly important because programmers can predict and code for multiple scenarios, but not for every possible scenario—thus pre-programmed robots are inevitably prone to failure.

“However, if you let these [new] robots learn from relevant experience, then they will eventually find a solution that, once found, will be put to use and adapted as needed. The solution may not be perfect, but will be adopted if it is good enough for the situation. Not every one of us needs or wants—or is able to spend the time and effort— to win an Olympic medal,” Marjaninejad said.

Through this process of discovering their body and environment, the robot limbs designed at Valero-Cuevas’ lab at USC use their unique experience to develop the gait pattern that works well enough for them, producing robots with personalized movements. “You can recognize someone coming down the hall because they have a particular footfall,” Valero-Cuevas said. “Our robot uses its limited experience to find a solution to a problem that then becomes its personalized habit, or ‘personality’—We get the dainty walker, the lazy walker, the champ… you name it.”

The potential applications for the technology are many, particularly in assistive technology, where robotic limbs and exoskeletons that are intuitive and responsive to a user’s personal needs would be invaluable to those who have lost the use of their limbs. “Exoskeletons or assistive devices will need to naturally interpret your movements to accommodate what you need,” Valero-Cuevas said.

“Because our robots can learn habits, they can learn your habits, and mimic your movement style for the tasks you need in everyday life—even as you learn a new task, or grow stronger or weaker.”

According to the authors, the research will also have strong applications in the fields of space exploration and rescue missions, allowing for robots that do what needs to be done without being escorted or supervised as they venture into a new planet, or uncertain and dangerous terrain in the wake of natural disasters. These robots would be able to adapt to low or high gravity, loose rocks one day and mud after it rains, for example.

The paper’s two additional authors, doctoral students Brian Cohn and Darío Urbina-Meléndez weighed in on the research:

“The ability for a species to learn and adapt their movements as their bodies and environments change has been a powerful driver of evolution from the start,” said Cohn, a doctoral candidate in computer science at the USC Viterbi School of Engineering. “Our work constitutes a step towards empowering robots to learn and adapt from each experience, just as animals do.”

“I envision muscle-driven robots, capable of mastering what an animal takes months to learn, in just a few minutes,” said Urbina-Meléndez, a doctoral candidate in biomedical engineering who believes in the capacity for robotics to take bold inspiration from life. “Our work combining engineering, AI, anatomy and neuroscience is a strong indication that this is possible.”

Learn more: A Robotic Leg, Born Without Prior Knowledge, Learns to Walk

 

 

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Real science has finally caught up to the science fiction of Iron Man’s transforming exoskeleton suit

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BYU researchers unfold new class of mechanical devices

In a paper published today in Science Robotics, engineers at Brigham Young University detail new technology that allows them to build complex mechanisms into the exterior of a structure without taking up any actual space below the surface.

This new class of mechanisms, called “developable mechanisms,” get their name from developable surfaces, or materials that can take on 3-D shapes from flat conformations without tearing or stretching, like a sheet of paper or metal. They reside in a curved surface (like, say, the arms of Iron Man’s suit) and can transform or morph when deployed to serve unique functions. When not in use, they can fold back into the surface of the structure seamlessly.

“These new discoveries make it possible to build complex machines that integrate with surfaces to be very compact, but can deploy and do complex tasks,” said researcher Larry Howell, professor of mechanical engineering at BYU. “It opens up a whole new world of potential devices that have more functions, but are still very compact.”

Making hyper-compact mechanisms is something increasingly important as manufacturers across medical, space and military industries are constantly working to get more complex functionality in less space. Potential applications of developable mechanisms include:

  • Medical: Surgical instruments that can both cut materials and deploy lights simultaneously during minimally-invasive surgery
  • Vehicles and airplanes: Storage components that could deploy from the inner surface of the fuselage and be completely out of the way when not in use
  • Military: Quad-rotor drones that have adjustable wing spans for fitting in tight spaces
  • Space: Wheels that could deploy claws for rock crawling, which could be especially useful to an interplanetary rover.

This new class of mechanical structures evolved from Howell and colleague Spencer Magleby’s work on origami-based engineering, done in collaboration with origami artist Robert Lang. From solar arrays for NASA to bulletproof barriers for police officers, their work has generated national and international coverage. As the group of researchers moved to curved origami principles, the mathematics revealed a new way of doing more complex machines.

“Origami was a stepping stone to this,” Magleby said. “The art of Origami has inspired us to do things that don’t even look like Origami, yet it is the core of much of this new engineering.”

The new line of research is sponsored by the National Science Foundation and includes researchers at BYU, the University of Southern Indiana and Lang Origami.

“It’s pretty cool to accomplish things that have merely been science fiction in the past,” Howell said. “These are discoveries that will enable us to do things that no one has ever been able to do before. And we hope that other engineers, as they build on these discoveries, will apply them in ways that will help make the world a better place.

Learn more: BYU researchers unfold new class of mechanical devices

 

 

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Robotic spine exoskeleton could lead to new treatments for children with spine deformities such as idiopathic scoliosis and kyphosis

Credit: Sunil Agrawal/Columbia Engineering
Robotic Spine Exoskeleton consists of two six-degrees-of-freedom parallel-actuated modules connected in series, each with six actuated limbs. Each module controls the translations/rotations or forces/moments of one ring in three dimensions with respect to the adjacent ring.Credit: Sunil Agrawal/Columbia Engineering
Robotic Spine Exoskeleton consists of two six-degrees-of-freedom parallel-actuated modules connected in series, each with six actuated limbs. Each module controls the translations/rotations or forces/moments of one ring in three dimensions with respect to the adjacent ring.

Designed by Columbia Engineers, RoSE is first device to measure 3D stiffness of human torso, could lead to new treatments for children with spine deformities such as idiopathic scoliosis and kyphosis

Spine deformities, such as idiopathic scoliosis and kyphosis (also known as “hunchback”), are characterized by an abnormal curvature in the spine. The children with these spinal deformities are typically advised to wear a brace that fits around the torso and hips to correct the abnormal curve. Bracing has been shown to prevent progression of the abnormal curve and avoid surgery. The underlying technology for bracing has not fundamentally changed in the last 50 years.

While bracing can stop/retard the progression of abnormal spine curves in adolescents, current braces impose a number of limitations due to their rigid, static, and sensor-less designs. In addition, users find them uncomfortable to wear and can suffer from skin breakdown caused by prolonged, excessive force. Moreover, the inability to control the correction provided by the brace makes it difficult for users to adapt to changes in the torso over the course of treatment, resulting in diminished effectiveness.

To address these deficiencies, Columbia Engineering researchers have invented a new Robotic Spine Exoskeleton (RoSE) that may solve most of these limitations and lead to new treatments for spine deformities. The RoSE is a dynamic spine brace that enabled the team to conduct the first study that looks at in vivomeasurements of torso stiffness and characterizes the three-dimensional stiffness of the human torso. The studywas published online March 30 in IEEE Transactions of Neural Systems and Rehabilitation Engineering.

“To our knowledge, there are no other studies on dynamic braces like ours. Earlier studies used cadavers, which by definition don’t provide a dynamic picture,” says the study’s principal investigator Sunil Agrawal, professor of mechanical engineering at Columbia Engineering and professor of rehabilitation and regenerative medicine at Columbia University Vagelos College of Physicians and Surgeons. “The RoSE is the first device to measure and modulate the position or forces in all six degrees-of-freedom in specific regions of the torso. This study is foundational and we believe will lead to exciting advances both in characterizing and treating spine deformities.”

Developed in Agrawal’s Robotics and Rehabilitation (ROAR) Laboratory, the RoSE consists of three rings placed on the pelvis, mid-thoracic, and upper-thoracic regions of the spine. The motion of two adjacent rings is controlled by a six-degrees-of-freedom parallel-actuated robot. Overall, the system has 12 degrees-of-freedom controlled by 12 motors. The RoSE can control the motion of the upper rings with respect to the pelvis ring or apply controlled forces on these rings during the motion. The system can also apply corrective forces in specific directions while still allowing free motion in other directions.

Eight healthy male subjects and two male subjects with spine deformities participated in the pilot study, which was designed to characterize the three-dimensional stiffness of their torsos. The researchers used the RoSE, to control the position/orientation of specific cross sections of the subjects’ torsos while simultaneously measuring the exerted forces/moments.

The results showed that the three-dimensional stiffness of the human torso can be characterized using the RoSE and that the spine deformities induce torso stiffness characteristics significantly different from the healthy subjects. Spinal abnormal curves are three-dimensional; hence the stiffness characteristics are curve-specific and depend on the locations of the curve apex on the human torso.

“Our results open up the possibility for designing spine braces that incorporate patient-specific torso stiffness characteristics,” says the study’s co-principal investigator David P. Roye, a spine surgeon and a professor of pediatric orthopedics at the Columbia University Irving Medical Center. “Our findings could also lead to new interventions using dynamic modulation of three-dimensional forces for spine deformity treatment.”

“We built upon the principles used in conventional spine braces, i.e., to provide three-point loading at the curve apex using the three rings to snugly fit on the human torso,” says the lead author Joon-Hyuk Park, who worked on this research as a PhD student and a team member at Agrawal’s ROAR laboratory. “In order to characterize the three-dimensional stiffness of the human torso, the RoSE applies six unidirectional displacements in each DOF of the human torso, at two different levels, while simultaneously measuring the forces and moments.”

While this first study used a male brace designed for adults, Agrawal and his team have already designed a brace for girls as idiopathic scoliosis is 10 times more common in teenage girls than boys. The team is actively recruiting girls with scoliosis in order to characterize how torso stiffness varies due to such a medical condition.

“Directional difference in the stiffness of the spine may help predict which children can potentially benefit from bracing and avoid surgery,” says Agrawal.

Learn more: First Dynamic Spine Brace—Robotic Spine Exoskeleton—Characterizes Spine Deformities

 

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