Assessment of an upper limb exosuit with textile coupling

Abstract

Exoskeletons are human-machine interaction devices that can either assist or oppose the user’s motion. Soft exoskeletons are lightweight devices whose lack of rigid pieces provides them with soft behaviour. These exosuits use textiles and soft actuation mechanisms to enhance compliance and comfort during user interaction. The absence of a rigid structure, thereby, provokes drawbacks related to force transfer and fixation of the system to the wearer’s anatomy. Commonly-reported issues include textile-slippery phenomena, pressure-related discomfort, actuation perturbations due to muscle volume variability and joint misalignment during human motion. This paper introduces the fixation solution adopted in LuxBit, a textile-wearable cable-driven exoskeleton to assist elbow and shoulder flexion. Different textiles and sewing patterns are combined in this coupling-interface to promote force distribution and adaption to the wearer’s anatomy. Then, the document assesses the assistance capability of the device by measuring the trajectory and electromyography signals of four subjects while flexing the elbow and shoulder up to 90 degrees. The experiments also allow discussing the benefits for a healthy user in both cases, when carrying a 0.75kg load and not.