Abstract:
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The main purpose of the present work is to study the application of industrial passive
exoskeletons in companies of the automotive sector in order to improve the workers wellness.
Biomechanical functional evaluation tests have been performed to document the real benefit
that the use of these exoskeletons would bring in the reduction of efforts registered in certain
muscle groups and related to the risk of musculoskeletal injury. Objective and quantitative
EMG signals have been used to test three different exoskeletons. The tests have been
performed in the actual under-floor workstations from Nissan plant at Zona Franca in
Barcelona.
From the signal four different variables have been studied: Maximum 10% EMG amplitude,
maximum 50% EMG Amplitude and Root-Mean Square (RMS) of the signal, as amplitude
variables to assess the muscle activation, and Mean Power Frequency (MPF), from the
frequency-domain to assess fatigue. Wilcoxon signed rank test (with a significance level of
α=5%) have been used to statistically report the significant differences.
From the obtained results, it must be highlighted that great reductions of muscle activity are
found at the shoulder area (up to 40% in deltoids). This illustrates that the studied exoskeletons
are useful for preventing injuries in Under-Floor (UF) tasks such as the studied ones. Especially
good results are obtained for the workstations with more aerial tasks (which imply higher
abduction angles at the shoulder joint), achieving, in some cases, reductions in the deltoids
above the 65%. Statistically significant reductions have been found, for at least one of the
exoskeletons tested, in deltoids, triceps, upper-trapezius and latissimus dorsi.
It should be kept in mind that this is a trial phase and that exoskeletons still have adverse
results in specific cases. But, based on the global results obtained, it can be concluded that
their usefulness will probably make them a reality very soon. |