Effects of Upper-Limb Exoskeletons Designed for Use in the Working Environment—A Literature Review

Abstract

Introduction: Many employees report high physical strain from overhead work and resulting musculoskeletal disorders. The consequences of these conditions extend far beyond everyday working life and can severely limit the quality of life of those affected. One solution to this problem may be the use of upper-limb exoskeletons, which are supposed to relieve the shoulder joint in particular. The aim of this literature review was to provide an overview of the use and efficacy of exoskeletons for upper extremities in the working environment.Methods: A literature review was conducted using the PICO scheme and the PRISMA statement. To this end, a systematic search was performed in the PubMed, Web of Science and Scopus databases in May 2020 and updated in February 2022. The obtained studies were screened using previously defined inclusion and exclusion criteria and assessed for quality. Pertinent data were then extracted from the publications and analyzed with regard to type of exoskeleton used as well as efficacy of exoskeleton use.Results: 35 suitable studies were included in the review. 18 different exoskeletons were examined. The majority of the exoskeletons only supported the shoulder joint and were used to assist individuals working at or above shoulder level. The main focus of the studies was the reduction of muscle activity in the shoulder area. Indeed, 16 studies showed a reduced activity in the deltoid and trapezius muscles after exoskeleton use. Kinematically, a deviation of the movement behavior could be determined in some models. In addition, study participants reported perceived reduction in exertion and discomfort.Discussion: Exoskeletons for upper extremities may generate significant relief for the intended tasks, but the effects in the field (i.e., working environment) are less pronounced than in the laboratory setting. This may be due to the fact that not only overhead tasks but also secondary tasks have to be performed in the field. In addition, currently available exoskeletons do not seem to be suitable for all overhead workplaces and should always be assessed in the human-workplace context. Further studies in various settings are required that should also include more females and older people.

Use of Lower Limb Exoskeletons as an Assessment Tool for Human Motor Performance: A Systematic Review

“…Further, the target population for exoskeletons in general is very heterogeneous. Research on exoskeletons is primarily carried out in the medical field [ 104 ], in addition to military use or use in the working environment [ 105 ]. Here, the focus is on diseases that severely restrict movement, such as stroke or paraplegia.…”

Passive shoulder exoskeleton support partially mitigates fatigue-induced effects in overhead work

“…Despite the potential of PSEs (de Looze et al, 2016), and their experimentally confirmed ability to reduce joint load, muscle activity and muscle fatigue during laboratory based overhead work (De Vries and De Looze, 2019;Bär et al, 2021;De Bock et al, 2022a;van der Have et al, 2022), large-scale adoption in industry is not yet forthcoming (Crea et al, 2021). This may partially be explained by the limited representativeness of laboratory studies Moeller et al, 2022) and the lack of generalizability of field studies (Crea et al, 2021;De Bock et al, 2022b;Kuber et al, 2022). Furthermore, effort expectancy, social influence, and performance expectancy determine the intention to use exoskeletons prior to testing an exoskeleton (Elprama et al, 2020), and perceived comfort, task-technology fit, perceived safety, and perceived usefulness affect the intention to use an exoskeleton after testing the device (Schwerha et al, 2022).…”

“…Even though the potential positive effects of PSEs on employees' health might be significant (de Looze et al, 2016;Moeller et al, 2022), some concerns towards precision performance remain. Overhead work endurance performance increases when wearing a PSE (Butler, 2016;Spada et al, 2017), which is confirmed by reductions in muscle activity and fatigue (De Vries and De Looze, 2019;Bär et al, 2021;De Bock et al, 2022a;Schmalz et al, 2019).…”

“…Most PSE assessments contain experimental conditions with short PSE wearing times during overhead work (Moeller et al, 2022) and showed the attenuation of muscle fatigue development (De Bock et al, 2022a;Schmalz et al, 2019). Nevertheless, fatigue could still occur during prolonged overhead work (Sood et al, 2007), yet no evidence documents the effect of PSEs in a physically fatigued state.…”

Evaluation of Active Shoulder Exoskeleton Support to Deduce Application-Oriented Optimization Potentials for Overhead Work

“…Active systems (e.g., shoulder exoskeleton S700 (exoIQ, Hamburg, Germany)), on the other hand, have the potential to regulate the support level during the use itself, adapting to the requirement of the manual task and individual wishes. Many studies have shown the effect of load reduction on workers with an exoskeleton [6][7][8]. Otten et al showed a possible reduction in shoulder muscle activity of up to 58.2% with the Lucy exoskeleton during overhead activities [9,10].…”