Explaining the ergonomic assessment of human movement in industrial contexts

The repetitive nature of manufacturing processes is identified as a risk factor for the onset of musculoskeletal disorders. For prevention, the operator’s exposure risk is measured through ergonomic risk scores which are often associated with a workstation, ignoring the variability among operators. Moreover, the score values hinder a comprehensive interpretation by occupational physicians. Observation methods require significant effort, preventing accurate and continuous evaluation. The conducted study developed a solution using inertial sensors for automatic operator risk exposure in the manufacturing industry. Two experimental assessments were conducted: laboratory validation, performed by 14 subjects, using an optical motion capture system as a reference; and field evaluation, with 6 participants, acquired on a real automotive assembly line, served as the basis for an ergonomic risk evaluation study. Through the research, it was implemented an upper-body motion tracking algorithm relying on inertial information, to estimate the angular orientation of anatomical joints. An adjusted ergonomic risk score, based on direct measurements was developed allowing an ergonomic evaluation which also has an explanation approach, based on the comprehensive analysis of the angular risk factors. Direct measurements fasten the ergonomic feedback, consequently, the evaluation can be extended to more operators, ultimately preventing work-related injuries.