People who believe that exoskeletons — wearable robots — are a distant, futuristic technology may be surprised by the fact the exoskeleton sales are projected to reach $2.1 billion by 2021, according to a 2015 report from Lexington, Mass.-based WinterGreen Research Inc.

In addition to helping military and civilian wearers accomplish a variety of tasks, robotics can also provide limb function to people with disabilities.

“Disability treatment with sophisticated exoskeletons is anticipated to providing better outcomes for patients with paralysis due to traumatic injury,” the report notes. “People using exoskeleton robots are able to make continued progress in regaining functionality even years after an injury.”

A path to recovery

Trevor Greene (above), who suffered a debilitating brain injury in 2006 from an axe attack while on duty in Afghanistan, fully understands the benefits of assistive technology. With the assistance of a customized exoskeleton developed at Simon Fraser University in Burnaby, British Columbia, the former soldier has recovered his ability to walk.

Greene started working with Ryan D’Arcy in 2009, shortly after the neuroscientist and Simon Fraser University professor saw a documentary about Greene’s injury. D’Arcy asked Greene to join him in a research project aimed at investigating how brain plasticity affects motor functions.

“Plasticity” refers to the brain’s ability to reorganize its neural pathways and synapses in response to a person’s behaviors, thoughts, or emotions. Greene met regularly with D’Arcy to provide functional magnetic resonance imaging (fMRI) scans of his brain, which D’Arcy used to track how the brain rewires itself.

Exoskeletons are generally designed for people with spinal cord injuries to provide lower leg movement. The D’Arcy-Greene project, however, marks the first time the technology has been used for someone with a brain injury.

After many months of testing and retesting, Greene is now able to walk upright with assistance, wearing a custom-made exoskeleton built by Yokneam, Israel-based ReWalk Robotics Ltd. He plans to eventually walk unassisted and, someday, to make his way to a Mount Everest base camp.

“Trevor has been extremely committed to his rehabilitation program,” D’Arcy said.

Help for hands

Brain damage can affect hands as well as legs. Yet therapy focused only on a person’s legs can leave hand muscles contracted, a condition that may be difficult to overcome.

“Part of the focus is to create a portable and independent system, capable of applying therapy without the constant supervision of a therapist,” said research team leader Muthu Wijesundara, a UTARI principal research scientist.

Wijesundara is working on the project with University of North Texas Health Science Center researchers Rita Patterson, Nicoleta Bugnariu, and Timothy Niacaris.

Neurological impairment or severe injury can create significant hand motion dysfunction in afflicted individuals. Existing commercial rehabilitation and assistive devices are based on conventional, rigid robotics, which often incorporate exoskeleton structures.

However, such devices tend to be mechanically complex, costly, large, and heavy. On the other hand, a soft robot typically offers inflatable structures that are less complex, relatively inexpensive, and considered a safer option. There are currently no commercial options for soft robotics on the rehabilitation market, the researchers said.

UTARI’s soft robotic glove incorporates a hybrid soft-and-rigid pneumatic actuator, a design that allows a low operating pressure, easy fabrication, a lightweight structure, and individual control of joints. The glove’s flexible nature enables it to be adapted to various medical conditions and anatomical features.

The system’s technology is based on another University of Texas-Arlington creation, the Bubble Actuator, an adaptive interface that fits between a prosthetic device and a patient’s limb to improve fit and comfort.

The National University of Singapore (NUS) is working on a similar portable device, named the EsoGlove.

“EsoGlove is designed to enable patients to carry out rehabilitation exercises in various settings — in the hospital wards, rehabilitation centers, and even at home,” said Raye Yeow, an assistant professor at the NUS Department of Biomedical Engineering.

Upper-body therapy

Researchers at the University of Texas at Austin have developed a two-armed robotic rehabilitation exoskeleton that promises to provide data-driven therapy to patients suffering from spinal and neurological injuries.

Mechanical engineering researcher Ashish Deshpande and a team of graduate students from the Rehabilitation and Neuromuscular (ReNeu) Robotics Lab designed the exoskeleton, named Harmony, to provide users with full upper-body therapy, natural motion, and tunable pressure and force, enabling the robot to feel virtually weightless.

Harmony’s software is designed to enable therapists and doctors to deliver precise therapy while tracking and analyzing data. The researchers said they hope that Harmony will be used to help patients recover strength and motor skills after injuries. The assistive device could help patients recover coordination for daily activities such as eating and dressing.

Harmony’s design accommodates the entire upper body, setting the robot apart from existing technologies that focus on only one arm and limit bilateral training possibilities. The exoskeleton connects to patients at three places on each side of the upper body and features 14 axes for a wide range of natural motion.

The robot’s sensors collect data at a rate of 2,000 times per second. The information is then fed back into the device to provide a highly personalized robotic interaction. With assistance from physical therapists and doctors, the researchers were able to design Harmony’s shoulder mechanism to facilitate natural, coordinated motions.

Most importantly, the robot helps restore scapulohumeral rhythm, a critical coordinated rotational motion necessary for upper-limb movements and long-term joint stability.

The researchers believe Harmony could significantly reduce a patient’s recovery time, since it can adapt to the specific ways that humans learn. High levels of force control and torque control enable the robot to gently correct a patient during an improperly performed robot-guided exercise.

Harmony can also be programmed to gradually increase exercise difficulty levels. Physical therapists can use the data Harmony collects during exercises to chart patients’ progress and tailor regimens to individual needs.

Efforts to harness the latest advances in biomechanics and robotics have been proliferating. Next, we’ll look at a lower-leg device and an exoskeleton for children.