A usabilidade de um modelo de exoesqueleto para membros superiores aplicado na indústria de abate e processamento de carnes, seus efeitos e impactos na redução do esforço físico

Abstract

The meat slaughtering and processing sector in Brazil presents high rates of occupational illness resulting from work-related musculoskeletal disorders (WMSDs), especially in repetitive activities involving elevation of the upper limbs. In this context, this research supports the thesis that the use of a passive upper-limb exoskeleton constitutes a technically feasible and ergonomically effective solution to reduce muscle activation and workers’ perceived exertion in meat processing plants. The general objective was to develop and apply a diagnostic model to evaluate the usability and ergonomic efficiency of the exoskeleton in repetitive tasks involving arm elevation above 45°, based on the parameters established by NR-36 and the ISO 11228 series. The study was carried out in a pork slaughtering industry, using surface electromyography (EMG) to measure the electrical activity of the anterior and medial deltoid muscles, the Borg Scale to assess subjective perception of exertion, and the System Usability Scale (SUS) questionnaire to measure the acceptability of the technology. The results showed visible reductions in the intensity of EMG signals in the anterior and medial deltoids, both on the left and right sides, during the use of the exoskeleton, evidencing clear differences between the conditions with and without the equipment, as well as average gains per task and positive linear correlations. Residual analysis reinforced the consistency of the data, and the normalized adjusted mean of the four studied muscles indicated a consistent reduction in effort, with lower normalized peak values during the use of the equipment. A decrease in perceived exertion was also observed through the Borg Scale, as well as high usability according to the SUS. The statistical results showed reductions in the adjusted mean values of the muscles, with confidence intervals indicating a tendency toward lower muscle activation during the use of the exoskeleton. The normalized peak values also showed consistent reductions, especially in the medial deltoids, with high effect sizes (Cohen’s d > 1.0). The Borg Scale demonstrated that, without the exoskeleton, 58.8% of the participants reported moderate exertion, whereas with the exoskeleton 100% reported light or very light exertion. The SUS confirmed high acceptability, with 88.2% of the participants classifying usability as excellent, exceeding the reference threshold of 68 points. The discussion reinforced that, although no statistically significant differences were observed, the practical effects are relevant for applied ergonomics. The reduction in muscle activation and perceived exertion, associated with high acceptability, corroborates the initial thesis and demonstrates that the exoskeleton has the potential to contribute to the prevention of WMSDs and compliance with the requirements of NR-36. The conclusions validate the feasibility of the exoskeleton as an ergonomic solution applicable in meat processing plants and potentially replicable in other productive environments, with caution regarding generalization and recommendation for future studies with expanded samples and longitudinal analyses.