Patrick Wensing and Katie Strausser
It can be all too easy to take the most basic human actions for granted, including the number of steps we take on any given day. According to the National Spinal Cord Injury Statistical Center, in the United States more than 300,000 people are recovering from spinal cord injuries, making the simple act of walking a challenge.
In rehabilitation centers and clinical settings, exoskeletons can help patients recover from spinal cord injuries by retraining the body to walk. Now, a new project led by the University of Notre Dame is focusing on making those machines more intuitive, using the fundamentals of human movement to improve rehabilitation outcomes and give patients a sense of control over their recovery.
“When it comes to robots and humans interacting, it’s a common challenge for robots to understand our goals and intentions,” said Patrick Wensing, assistant professor in the Department of Aerospace and Mechanical Engineering at Notre Dame. “Human-machine interface technologies traditionally operate without physical models of movement. The main goal of this project is to use the fundamental mechanics of walking to inform user intent recognition.”
Wensing and his team are working in collaboration with Ekso Bionics, a leading developer of wearable exoskeletons. The National Science Foundation is funding the three-year project as part of its National Robotics Initiative.
The use of an exoskeleton as part of rehabilitation and recovery is predicated by the need for a human operator to guide the machine, controlling the gait speed and guiding the patient.
“The exoskeleton is trying to follow a certain gait,” Wensing said. “You can configure it to provide a variable amount of assistance, but if you want to stop, start or change your speed, you often need someone to do that for you by using a button interface on the device.”
Other methods have focused on electromyography sensors, a process through which sensors are applied to the skin or embedded into muscles to sense the electrical signals that activate movement. The process can be noisy, invasive and not necessarily more effective. “What we’re trying to do is enable existing products to have more impact by making them more intuitive to operate,” Wensing said. The team wanted to work with Ekso Bionics for its broad FDA clearance and the base of injury level its exoskeletons can be used with, including the highest level of spinal cord injury.
During experiments the team has planned for later this summer, operators will use an exoskeleton and attempt to manipulate its movement by intentionally speeding it up and slowing it down. The team will then analyze movement cues to develop new intent detection technology, which the researchers will also implement and test as part of the project.
Developing a more intuitive machine, free from the need of a human operator, could improve the process of rehabilitation, allowing the patient to take even more steps per session and speed up the process of retraining the body to walk — but the tangential effects could have a greater impact.
The average age of individuals with a spinal cord injury is 42 years old at first injury, Wensing said. Those patients are often temporarily or permanently displaced from the workforce or encounter barriers sometimes outside of their control, such as financial and health care issues, accessibility and employer attitudes. However, studies have shown that patients with spinal cord injuries are more likely to return to work with supportive rehabilitation professionals, family and community members, as well as with a growing restoration of their own independence.
Exoskeletons are also used to enhance the mobility of individuals who have experienced severe stroke or neurotrauma. More than 6.4 million stroke survivors live outside of long-term care facilities in the United States, according to the American Heart Association. Those individuals could benefit from machines that are more intuitive. Getting access to exoskeletons in clinical and rehabilitation settings is also a challenge — and if you want one for home, they are not covered currently by insurance. As technology improves, Wensing said a case could be made to insurance companies that it’s in their best interest to fund exoskeletons for recovery.
“As a patient living with one of these injuries, if you’re in control of your own movement, you maintain more of your dignity and regain your own former independence,” Wensing said. “When taking steps with these devices, it empowers you to stick with the program, to go back to rehab and follow through.”
Researchers are currently analyzing existing data provided by Ekso Bionics exoskeletons and will conduct experiments onsite at the company’s headquarters in northern California.
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