Objective and Subjective Effects of a Passive Exoskeleton on Overhead Work

Abstract

Overhead work is a frequent cause of shoulder work-related musculoskeletal disorders. Exoskeletons offering arm support have the potential to reduce shoulder strain, without requiring large scale reorganization of the workspace. Assessment of such systems however requires to take multiple factors into consideration. This paper presents a thorough in-lab assessment of PAEXO, a novel passive exoskeleton for arm support during overhead work. A list of evaluation criteria and associated performance metrics is proposed to cover both objective and subjective effects of the exoskeleton, on the user and on the task being performed. These metrics are measured during a lab study, where 12 participants perform an overhead pointing task with and without the exoskeleton, while their physical, physiological and psychological states are monitored. Results show that using PAEXO reduces shoulder physical strain as well as global physiological strain, without increasing low back strain nor degrading balance. These positive effects are achieved without degrading task performance. Importantly, participants' opinions of PAEXO are positive, in agreement with the objective measures. Thus, PAEXO seems a promising solution to help prevent shoulder injuries and diseases among overhead workers, without negatively impacting productivity.

The Effects of Upper-Body Exoskeletons on Human Metabolic Cost and Thermal Response during Work Tasks—A Systematic Review

“…Table 1 shows an overview of the main characteristics of the nine considered studies [ 26 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ], following the PICO model and highlighting the type of exoskeleton used. All the articles that met the eligibility criteria are very recent—eight were published between 2019 and 2020 and one, the oldest, in 2014.…”

“…All the studies were carried out in the laboratory. Most of them (six out of nine, [ 38 , 40 , 41 , 42 , 44 , 45 ]), chose a repetitive lifting task to be performed in the experimental trial, two out of nine [ 26 , 39 ] selected an overhead working task and one considered a static holding posture of the trunk [ 43 ]. All the studies were based on the comparison between the “with exoskeleton condition (WEC)” and “without exoskeleton condition (WOEC)”.…”

“…All the studies were based on the comparison between the “with exoskeleton condition (WEC)” and “without exoskeleton condition (WOEC)”. One study [ 38 ] considered two different exoskeletons; another one [ 26 ] tested the same exoskeleton but with different angle-moment settings.…”

“…In total, eight different UBEs were investigated: seven BSEs [ 38 , 40 , 41 , 42 , 43 , 44 , 45 ] and one ULSE [ 26 , 39 ]. Among them, seven were passive assistive devices and one [ 45 ] was an active device.…”

“…This acceptance is strongly related to the discomfort and usability of exoskeletons, especially when they are used for a long time. Workers’ acceptance can be tested by performing subjective measurements aiming to investigate aspects related to the physical demand, constraints, perceived usefulness, ease of use, intention to use and performance [ 26 ]. There are some issues that remain open regarding the long-term effects of exoskeletons on human biomechanics and physiology [ 25 ], the “transference of risk” [ 2 ]—i.e., the occurrence of other risks caused by the presence of exoskeletons—and the lack of scientific evidence on the ergonomic aspects related to the use of exoskeletons in workplaces [ 25 ].…”