Work-related musculoskeletal disorders (WMSDs) continue to occur despite an increasing understanding of the risk factors that initiate these disorders. Ergonomics is commonly seen as a health and safety approach that has no influence on performance, a perspective potentially hindering intervention proposals in practice. Highlighting potential performance benefits can facilitate intervention cost-justification, along with the traditional focus on reducing exposure to injury risk.
The main objective of this research was to examine the dual influences (i.e., on performance and injury risk) of two distinct types of interventions: adding adjustability, as a commonly advocated approach when considering ergonomics early in the (re)design phase to change task demands; and using exoskeletons to enhance worker capacity. A simulated drilling task was used, which was considered informative as it entailed diverse demands (precision, strength, and speed) and permitted quantifying two dimensions of task performance (productivity and quality).
The dual influences of three levels of workstation adjustability were examined first; increasing adjustability improved performance, with this benefit occurring only when a given level of adjustability also succeeded in reducing ergonomic risk. Across examined conditions, several significant linear associations were found between risk (e.g., Strain Index score) and performance metrics (e.g., completion time), further supporting an inverse relationship between these two outcomes. The dual influences of three distinct passive exoskeletal designs were investigated/compared subsequently, in a simulated overhead drilling task and considering the potential moderating effects of tool mass and precision requirements. Specific designs were: full-body (Full) and upper-body (Arm) exoskeletons with attached mechanical arms; and an upper-body (Shl) exoskeleton providing primarily shoulder support. Both designs with mechanical arms increased static and median total muscle activity while deteriorating quality. The Shl design reduced shoulder loading while increasing dominant upper arm loading and deteriorating quality in the highest precision requirements. Influences of both increasing precision and tool mass were fairly consistent across the examined designs. As such, no single design was obviously superior in both physical demands and performance. Although future work is needed under more diverse/realistic scenarios, these results may be helpful to (re)design interventions that achieve dual benefits on performance and injury risks. / PHD / Occupational injuries continue to occur despite an increasing understanding of what can cause these injuries. A potential reason for this continuing problem is that Ergonomics is commonly seen as a health and safety approach that has no influence on performance. This perspective can hinder approving/funding interventions that aim to reduce injury risk in workplaces. Emphasizing that these interventions can also improve performance (and lead to more profits) can better convince decision makers to approve them, and subsequently reduce injury risk. The primary objective of this dissertation was to examine the influences of two types of ergonomic interventions on both performance and injury risk. Three experiments were completed in the context of a simulated drilling task. This specific task was considered informative, as it entailed diverse demands (precision, strength, and speed) and permitted quantifying two dimensions of task performance (productivity and quality). Examined interventions were: 1) adding adjustability, as a commonly advocated approach when considering Ergonomics early in the (re)design phase to change task demands; and, 2) using exoskeletons, to potentially enhance worker capacity. For the former, increasing adjustability improved performance. However, this benefit occurred only when a given level of adjustability also succeeded in reducing injury risk. This suggests that reducing injury risk is associated with increasing performance. For exoskeletons, the dual influences of three distinct exoskeletal designs were investigated/compared in a simulated overhead drilling task. The potential effects of tool mass and precision requirements were also considered. Specific designs were: full-body and upper-body exoskeletons with attached mechanical arms; and an upper-body exoskeleton providing primarily shoulder support. Both designs with mechanical arms increased overall muscle activity while deteriorating quality. The shoulder-focused design reduced shoulder demands while increasing demands on the dominant upper arm and deteriorating quality in the highest precision requirements. Effects of both increasing precision requirements and tool mass were fairly consistent across the examined designs. As such, no single design was obviously superior in both physical demands and performance. These results may be helpful to (re)design interventions that achieve dual benefits on performance and injury risks. However, future work is needed under more diverse/realistic scenarios.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/89485 |
| Date | 16 November 2017 |
| Creators | Alabdulkarim, Saad A. |
| Contributors | Industrial and Systems Engineering, Nussbaum, Maury A., Dickerson, Deborah Elspeth, Kim, Sun Wook, Srinivasan, Divya |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Dissertation |
| Format | ETD, application/pdf, application/pdf, image/jpeg, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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