Electromagnetic Clutch-Based Ankle Exosuit for Assisting Stroke Survivors With Different Body Sizes

Abstract

Exosuits can be effective in aiding stroke rehabilitation. However, single-motor exosuits are <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">challenging</b> to adapt to users with different body sizes. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Methods:</i> This letter proposes an electromagnetic clutch-based ankle exosuit (ECAE) for stroke survivors with different body sizes. This exosuit includes a single-motor actuation unit, two novel electromagnetic ratchet clutches, and functional textiles. Compared with other ankle rehabilitation robots, this exsouit could adapt to different users in terms of adaptive preload after wearing, maintaining device transparency when unpowered, and providing timely assistance. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Experiments:</i> Benchtop experiments were constructed to evaluate the property of designed clutches. Fifteen healthy subjects with different body sizes wore the ECAE to verify its adaptive performance. Then, they walked with unpowered and powered exosuits to validate transparency and timely assistive performance, respectively. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Results:</i> Designed clutches have a fast switching response (<20 ms). The ECAE could adaptively adjust the cable length with a slight preload (0.32–1.31 N) for different users. Compared with this exosuit without designed clutches, device transparency is increased by 84.58% (P < 0.001), and the assistive delay time is reduced by 57.77% (P < 0.004). <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Conclusion:</i> This ECAE could adapt to different users without needing customization, which could reduce the price of exosuits.