Full-body powered exoskeletons for industrial workers have the potential to reduce the incidence of work-related musculoskeletal disorders while increasing strength beyond human capabilities. However, operating current full-body powered exoskeletons imposes different loading, motion, and balance requirements on users compared to unaided task performance, potentially resulting in additional mental workload on the user which may reduce situation awareness (SA) and increase risk of collision with pedestrians, negating the health and safety benefits of exoskeletons. Exoskeletons could be equipped with visual aids to improve SA, like rearview cameras or radar displays. However, research on design and evaluation of such displays for exoskeleton users are absent in the literature.
This empirical study compared several augmented reality (AR) head-up displays (HUDs) in providing SA to minimize pedestrian collisions while completing common warehouse tasks. Specifically, the study consisted of an experimental factor of display abstraction including four levels, from low to high abstraction: rearview camera, overhead radar, ring radar, and no visual aid (as control). The second factor was elevation angle that was analyzed with the overhead and ring radar displays at 15°, 45°, and 90°. A 1x4 repeated measures ANOVA on all four display abstraction levels at 90° revealed that every display condition performed better than the no visual aid condition, the Bonferroni post-hoc test revealed that overhead and ring radars (medium and high abstraction respectively) received higher usability ratings than the rearview camera (low abstraction). A 2x3 repeated measures ANOVA on the two radar displays at all three display angles found that the overhead radar yielded better transport time and situation awareness ratings than the ring radar. Further, the two-way ANOVA found that 45° angles yielded the best transport collision times. Thus, AR displays presents promise in augment SA to minimize collision risk to collision and injury in warehouse settings. / Master of Science / Exoskeletons can increase the strength capabilities of industrial workers while reducing the likelihood of injury from heavy lifting and materials handling. However, full-body powered exoskeletons are currently very unwieldy, demanding users to focus their attention on controlling the exoskeleton that may cause a loss awareness of their surroundings. This may increase the likelihood of collisions with pedestrians, presenting a significant safety concern that could negate the benefits of exoskeletons. Rearview cameras and radar displays of nearby pedestrians could improve situation awareness for the exoskeleton user; however, these methods are not well-tested in settings where exoskeletons would be used. This study compared a rearview camera, a conventional radar, and a ring-shaped radar at display angles of 15°, 45°, and 90° using an augmented reality headset and simulated warehouse task to determine the combination of display type and angle that would maximize situation awareness and minimize collisions with pedestrians. The study revealed that all displays performed better than no display support and the latest evidence from this study and the literature suggests that a conventional overhead radar at 45° performed best.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/118434 |
| Date | 19 March 2024 |
| Creators | Hollister, Mark Andrew |
| Contributors | Industrial and Systems Engineering, Lau, Nathan Ka Ching, Srinivasan, Divya, Gabbard, Joseph L. |
| 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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