Work-related musculoskeletal disorders (WMSDs) cost US industries billions annually and reduce quality of life for those afflicted. Passive exoskeletons (EXOs) have emerged as a potential intervention to reduce worker exposures to WMSD risk factors. As EXO adoption is rising, EXO manufacturers are designing and producing new EXOs in accordance with growing demand. However, there are no standardized EXO evaluation protocols and EXO use recommendations, due in part to insufficient information on the reliability of EXO evaluation measures. The purpose of this thesis was to quantify the reliability of common EXO evaluation measures, using both traditional approaches a more advanced statistical approach (i.e., Generalizability Theory), while also identifying potential effects of EXO type, work task, and individual differences. This work used data from a recently completed EXO evaluation study, conducted in Virginia Tech's Occupational Ergonomics and Biomechanics Lab. Forty-two total participants completed simulated occupational tasks, in two separate experimental sessions on different days, while using an arm-support EXO (ASE) and a back-support EXO (BSE). Several outcome measures reached excellent within-session reliability within four trials for many tasks considered. Between-session reliability levels were lower than within-session levels, with outcome measures reaching moderate-to-good reliability for most tasks. Interindividual differences accounted for the largest proportion of variance for measurement reliability, followed by the experimental session. For all tasks, outcome measures reached excellent dependability levels, with many achieving excellent levels within five total trials. Inconsistencies observed in between-session reliability levels and dependability levels suggest that additional training and EXO familiarity may affect measurement reliability of outcome measures differently for some tasks, unique to each EXO type. These discrepancies emphasize the importance for additional research into this topic. Overall, the current findings indicate that many of the commonly used EXO evaluation measures are reliable and dependable within five trials and one experimental session, providing a potential foundation for standardized EXO assessment protocols. / Master of Science / Work-related musculoskeletal disorders (WMSDs) are a substantial economic burden and impair the quality of life for affected workers. Passive exoskeletons (EXOs), which use springs or elastic material to distribute the load placed on workers during manual labor, are a possible solution to reduce worker exposure to WMSD risk factors. EXO adoption is rising, but there are no standardized procedures to test the effectiveness of EXOs or standardized recommendations for EXO use. The purpose of this thesis was to determine the reliability of EXO evaluation measures commonly used in prior research, using both traditional reliability calculation methods alongside a more advanced method (i.e., Generalizability Theory). Data from a recently completed study were used, which were collected from 42 participants in two separate experimental sessions on two different days. Participants completed tasks intended to simulate manual work, using either an arm-support exoskeleton – which supported their upper arms during relevant tasks, or a back-support exoskeleton – which supported their lower back during relevant tasks. Many of the tasks and outcome measures reached excellent reliability within four repetitions in a single day. When examining reliability of evaluations across days, we found reliability levels were lower than levels obtained from a single day. All tasks and outcome measures reached excellent dependability levels, with many requiring only five trials to reach excellent levels. Reliability increased with the number of trials in an EXO evaluation experiment. Moreover, our results revealed that the EXO type being used and the biological sex of a participant both influence reliability, but individual participant differences had the greatest effect on measurement reliability. This research reveals possible experimental conditions required for reliable, efficient, and cost-effective EXO research, facilitating the development of a standardized EXO evaluation protocol.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/120953 |
| Date | 16 August 2024 |
| Creators | Noll, Alexander Baldrich Benoni |
| Contributors | Industrial and Systems Engineering, Nussbaum, Maury A., Kim, Sun Wook, Madigan, Michael L., Lim, Sol Ie |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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