Influences of different exoskeleton designs and tool mass on physical demands and performance in a simulated overhead drilling task

We compared different passive exoskeletal designs in terms of physical demands (maximum acceptable frequency = MAF, perceived discomfort, and muscular loading) and quality in a simulated overhead drilling task, and the moderating influence of tool mass (similar to 2 and similar to 5 kg). Three distinct designs were used: full-body and upper-body exoskeletons with attached mechanical arms; and an upper-body exoskeleton providing primarily shoulder support. Participants (n = 16, gender-balanced) simulated drilling for 15 min to determine their MAF, then maintained this pace for three additional minutes while the remaining outcome measures were obtained. The full-body/upper-body devices led to the lowest/highest MAF for females and the lowest quality. The shoulder support design reduced peak shoulder muscle loading but did not significantly affect either quality or MAF. Differences between exoskeleton designs were largely consistent across the two tool masses. These results may be helpful to (re)design exoskeletons to help reduce injury risk and improve performance.