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KnExo, Design, Development, and Functional Evaluation of a Bio-joint Shaped Knee Exoskeleton Assisting in Sit to Stand
  • Omid Arfaie,
  • Ramazan Unal
Omid Arfaie

Corresponding Author:[email protected]

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Ramazan Unal

Abstract

In addressing age-related muscle strength decline among elderly individuals, the development of assistive devices for daily living becomes imperative. This paper introduces a passive knee exoskeleton designed to aid older adults during sit-to-stand movements. Inspired by knee joint biomechanics encompassing rotational and translational motions, this exoskeleton employs a cam mechanism. This mechanism facilitates thigh rotation within a linear slot, adjusting the exoskeleton's rotational center and effectively minimizing misalignment with the body's knee joint. As the upper part attached to thigh rotates within the cam mechanism, a spring in the lower part attached to the shank compresses via a crank, storing energy during the sitting phase and releasing it during standing. The evaluation involves using an instrumented chair and footplate to collect force data during sit-to-stand motions. Force sensor resistors are positioned to measure force and pressure distribution across various regions. Notably, the developed knee exoskeleton (KnExo) provides 25% and 31% assistance of body weight under no-loaded and loaded (with a 20kg load) conditions, respectively, according to initial functional evaluation. Furthermore, compared to a revolute joint, the proposed knee exoskeleton exhibits a substantial 51% reduction in misalignment with the user's knee joint. This underscores its potential as an effective assistive device for elderly individuals coping with diminished muscle strength.
20 Jan 2024Submitted to TechRxiv
26 Jan 2024Published in TechRxiv