Comparative evaluation of cervical exoskeletons using IMUs

Abstract

Musculoskeletal disorders and pain in the neck and shoulders are commonly reported in workers whose activities imply overhead tasks. Repetitive passive head support or traumatic movements of the neck can cause damage to the ligaments and tendons of this region, with mild to severe long-term consequences. Exoskeletons are one of the solutions to help workers and their evaluation requires scientific methods and protocols to prove their effectiveness and make recommendations (Crea et al., 2021) (De Bock et al., 2022). Cervical exoskeletons could therefore be a valuable ergonomic solution to reduce stress on the neck and shoulders. However, while the growth of exoskeleton technology has led to multiple systems available on the market, it is still difficult to objectively determine which type or model of neck exoskeleton is the best adapted for overhead work and if the user’s perception matches with biomechanical outcomes.In this randomized crossover design study, 8 participants (3 women) performed dynamic and static extensions of the head in sitting position without trunk support for a period of 3 minutes (then 3 minutes of rest) while wearing three different head/neck exoskeletons in comparison with a situation without an exoskeleton. This allowed us to evaluate comfort, utility, usability, safety and impact (AFNOR, 2017) (Giovanelli & Touchard, 2018). A solution, based on synchronized merger of wireless inertial sensors, EMG signals, Polar OH1+ optical heart rate sensor (Hettiarachchi et al., 2019) and videos of the task (Motion CAPTIV, TEA, France) (Peeters et al., 2019) was used to examine joint angles of the head and spine movements, the bioelectrical activity of the sternocleidomastoid muscle and heart rate. Further these biomechanical and physiological outcomes, the perception of intensity was assessed by the Borg scale (Meyer, 2014) : CR10 Scale for the cervical and lumbar spine as well by the Rated Perceived Exertion (RPE) Scale for the global level of activity.The synthesis of this comparative analysis was carried out and compiled in the form of a conceptual basis from the C-K theory (Hatchuel & Weil, 2003) from the analysis of the design logic of exoskeletons.The results of this comparative analysis showed differences in terms of comfort, utility, usability, safety depending on the design logic of the solutions tested, but also depending on the morphology of the testers.