Passive shoulder exoskeleton reduces negative effects of fatigue on overhead precision task

Research output: Unpublished contribution to conferencePoster


Introduction: Occupational passive shoulder exoskeletons (PSE) contribute to relieve overhead work. However, limited insights in overhead working performance impede large-scale adoption in industry. Objective: Investigate the effect of PSE during overhead tasks in a fatigued state. Methods: Randomized, counterbalanced cross-over design with two levels of PSE support (SUP and NoSUP) and two levels of intervention (peripheral fatigue (FAT) and control). Participants were blinded for the PSE’s assistance level support. In each trial, an overhead drilling task was performed before and after executing the intervention protocol. Muscle activity and subjective workload (NASA-TLX) were assessed. EMG signals were rectified and filtered (4th order Butterworth, frequency cut of 10 Hz). The effect of the level of support, the intervention and time were assessed using linear mixed-effects regressions. Results: The PSE support did not significantly affect fatigue-induced changes in muscle activity. Nonetheless, the average muscle activity was significantly lower in SUP compared to NoSUP (p<0.002) for the deltoideus (anterior, medialis, posterior). Moreover, with and without PSE support, FAT increased mental and physical demand and decreased perception of performance. Conclusion: During overhead work, while PSE support decreased activity of muscles working to elevate the arm, it did not impact fatigue induced changes, nor altered subjective experience. Thus, the challenge is that users perceive the benefits of PSE support even in a fatigued state. This way there could be higher user acceptance and higher interest by the industry. Future studies identifying a trade-off between perceived effort and physiological performance improvements through human-robot interaction are necessary.
Original languageEnglish
Publication statusAccepted/In press - Aug 2022

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RehabWeek 2022


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