• occupational exoskeleton - muscle coactivation

Work-related musculoskeletal disorders (WMSDs) are one of the most spread illness conditions affecting workers in industries, impacting on their health, healthcare costs and productivity at workplace. One of the main aspects related to an increased probability to develop WMSDs is muscle coactivation, which is directly correlated with different biomechanical and physiological factors. This thesis focuses on the evaluation of muscle coactivation through the computation and assessment of coactivation indices present in literature. In particular, after a preliminary study and evaluation of five coactivation indices, in this thesis the time-varying coactivation function (TMCf) was identified as the one capable of providing the necessary amount of information about muscular coactivation in the shoulder. The TMCf index was applied to two different kind of datasets representing dynamic and static gestures performed by healthy individuals in stereotyped simulated working activities. The main goal of this thesis was to verify whether the use of occupational upper-limb exoskeletons could reduce the muscles’ coactivation with respect to the condition where the exoskeletons were not worn.
Results showed that muscle coactivation decreased when using the exoskeletons. Additionally, muscle coactivation reduced as the amount of assistance, namely the amplitude of antigravitational support provided by the exoskeleton, increased. Such results were consistent between dynamic and static tasks.
Future works will need to investigate the muscle coactivation also on real working conditions, such as with real workers during their daily routine working activities, to generalize the results achieved in this thesis.