Exoskeletons in rehabilitation

A stroke or an accident are life-changing events since many survivors experience limitations of mobility. Not all patients regain full mobility with subsequent rehabilitation. Some physical restrictions may persist, making adaptive equipment and assistive technologies necessary. Exoskeleton use in rehabilitation shows promise for better treatment results.

In clinics and hospitals around the world, exoskeletons have become a valuable tool in rehabilitation. As an exoskeleton technology provider for treatment facilities, this is something Ekso Bionics Europe GmbH can attest to. Stephan Aderhold, Vice President Sales & Marketing EMEA is excited: "This year marks the 10-year anniversary of Ekso! Over the past 10 years, our mission remained unchanged – namely, helping people regain functional mobility and improve their quality of life. We provide innovative cutting-edge technology for both outpatient and inpatient rehabilitation centers and are very proud to offer this technology in over 400 rehabilitation centers worldwide."

Things one needs for therapy: the exoskeleton, the patient, the therapist, and a lot of patience. Contrary to what non-experts might think, it takes more than just putting on the exoskeleton to start walking. While the robotics of the exoskeleton takes over certain movements or supports their execution, users must trigger and initiate some of these motions themselves.

The EksoNR from Ekso Bionics was developed for neurorehabilitation and is suitable for stroke patients and patients suffering from other neurological diseases who are affected by an abnormal gait. During the treatment session, the therapist operates the device via a touchscreen controller. The tool uses real-time feedback, which allows the therapist to customize the session to the user’s special needs. Apart from gait training, the device is also designed to help users balance and practice sit-to-stand positions and standing. This enables patients to relearn and regain lost motor functions.

To properly support the movements of the person wearing them, exoskeletons must fit properly. Sometimes that requires complex adjustments that depend on the respective application. It’s not as easy as it sounds as researcher of the University of Michigan and the University of Stuttgart discovered. David Remy is a Full Professor at the Institute for Nonlinear Mechanics at the University of Stuttgart and a researcher in this field. He points out that exoskeletons are usually not ready for immediate use and sometimes require adjustments that take half a day or even an entire day. He and his research team want to make it possible to adjust the device in less than two minutes (check out this press release for a description of the project)! The key is subjective feedback.

Remy describes the experimental setup, which uses an ankle exoskeleton and a touchscreen and had users walk on a treadmill: "The users were asked to click on any point in a two-dimensional grid on the screen of a tablet. They were told that this choice affects the configuration of the exoskeleton, but they were not told how this happens. While they walked with the exoskeleton, users were then asked to try different configurations until they found their preferred setting. We left the interpretation of ‘preference’ up to the participants. Behind the scenes, a computer used the selected points to calculate parameters for the torque and timing values that control the exoskeleton’s support and fed them into a control unit. We changed the mapping between the points on the touchscreen and the parameters with each repetition of the experiment. This means that in the first test, points further to the right prompted a higher level of support, while points were located higher up in the next test and so on. This allowed us to repeat the experiment, with users never finding their preferred, individual setting at the same point on the screen. We could show that the subjective preference is a very constant and reliably measurable value."

Professor Remy expects that this method will be used in three to five years to make exoskeleton adjustments. If you would like more information about exoskeletons, REHACARE 2022 showcases various exhibitors and a special exhibit area in Hall 6 featuring this topic.