Until recently, wearable robotic devices that could enhance a user’s physical abilities were largely the stuff of science fiction. Real-life prototypes existed, but were too costly, cumbersome, and uncomfortable for “practical,” everyday use. However, new research hints at an imminent revolution in the design of robotic exoskeletons and other devices. Here, we review two studies that are especially promising for people with movement disorders such as cerebral palsy.
Exoskeletons: not just for Iron Man
For many people, the term “robotic exoskeleton” evokes the image of a suit like that worn by Iron Man. Indeed, attempts to create real-life exoskeletons have been similar in design and often created with the aim of bestowing super strength. While such suits may have military potential, the cost alone is enough to prevent individual civilians from reaping their benefits. Moreover, they are generally uncomfortable and difficult to use (1).
Steve Collins, a researcher at Carnegie Mellon in Pittsburgh, Pennsylvania, believes that the future of robotic exoskeletons lies in minimalist designs targeted for individual needs. His research team has created a software-controlled ankle brace that helps people with physical impairments to walk without becoming quickly exhausted. These braces apply torque (a rotational force) at different time intervals and with different amounts of power. To determine what would be the most effective for each study participant, the researchers connected them to a breath monitor that recorded their oxygen consumption – a proxy of energy use – while doing physical tasks in ankle braces with different torque settings. With this method, they were able to customize the braces and substantially reduce energy expenditure (2). Collins predicts that in the next five years, it will become common to see people wearing exoskeletons in everyday life (1).
Children with cerebral palsy may benefit from robotic training method
People with cerebral palsy often walk with what is commonly referred to as “crouch gait,” due in part to weakness in the soleus muscles. Soleus muscles run from just below the knee to the heel and are used when extending the leg. Researchers from the School of Engineering and Applied Science at Columbia University designed the Tethered Pelvic Assist Device (TPAD) with the aim of strengthening the soleus muscles in children with cerebral palsy. TPAD is a comfortable, cable-driven robot that users wear while walking on a treadmill. Rather than adding mass or inertia to the body, it applies external forces – specifically a downward pelvic pull – on the user. A six-week pilot study on six children with cerebral palsy showed that this device improved the participants’ upright posture, muscle coordination, step length, and range of motion (3, 4). The researchers also received very positive feedback from the children and their parents. Emphasizing that there is currently no highly-effective physical therapy for crouch gait, team leader Sunil Agrawal expressed optimism about the effect TPAD could have on children with cerebral palsy.
Take-away: The future of wearable robotic devices for people with cerebral palsy
While still in the testing and development phase, technologies like those we have outlined today could be life changing for people with cerebral palsy and other motor conditions.
- Robotic Exoskeleton Adapts While It’s Worn
- Human-in-the-loop optimization of exoskeleton assistance during walking
- Robot-driven downward pelvic pull to improve crouch gait in children with cerebral palsy
- Robotic Training Method May Improve Gait, Posture in Kids with Cerebral Palsy, Researchers Say