Browsing by Author "Park, Hanjun"

Now showing 1 - 6 of 6
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    Changes in kinematics and muscle activity when learning to use a whole-body powered exoskeleton for stationary load handling
    Park, Hanjun; Kim, Sunwook; Nussbaum, Maury A.; Srinivasan, Divya (SAGE, 2022-10-11)
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    Effects of using a whole-body powered exoskeleton during simulated occupational load-handling tasks: A pilot study
    Park, Hanjun; Kim, Sunwook; Nussbaum, Maury A.; Srinivasan, Divya (Elsevier, 2022-01-01)
    Whole-body powered exoskeletons (WB-PEXOs) can be effective in reducing the physical demands of heavy occupational work, yet almost no empirical evidence exists on the effects of WB-PEXO use. This study assessed the effects of WB-PEXO use on back and leg muscle activities during lab-based simulations of load handling tasks. Six participants (4M, 2F) completed two such tasks (load carriage and stationary load transfer), both with and without a WB-PEXO, and with a range of load masses in each task. WB-PEXO use reduced median levels of muscle activity in the back (∼42–53% in thoracic and ∼24–43% in lumbar regions) and legs (∼41–63% in knee flexors and extensors), and mainly when handling loads beyond low-moderate levels (10–15 kg). Overall, using the WB-PEXO also reduced inter-individual variance (smaller SD) in muscle activities. Future work should examine diverse users, focus on finding effective matches between WB-PEXO use and specific tasks, and identify applications in varied work environments.
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    Effects of using passive back- and arm-support exoskeletons for cart pushing and pulling
    Park, Hanjun; Noll, Alex; Kim, Sunwook; Nussbaum, Maury A. (SAGE, 2023-10-20)
    Though studies have shown both BSEs and ASEs are effective in reducing physical demands for various manual material handling tasks, limited evidence is currently available on their effects in pushing and pulling tasks. We evaluated the impacts of using a passive back-support (BSE) and an arm-support exoskeleton (ASE) on trunk kinematics, and the back and arm musculature for pushing and pulling of a moderately loaded (100 kg) cart. Fourteen volunteers performed cart the tasks, each of whom was randomly assigned one of the exoskeletons (BSE or ASE). Wearing the BSE substantially reduced lumbar muscle activity during both pushing (up to ~39%) and pulling (up to ~35%) compared to not wearing EXOs, while wearing an ASE had no significant impacts. For the anterior deltoid muscle, neither BSE nor ASE had beneficial impacts. Findings from the current study help to understand the effects of BSEs and ASEs in pushing and pulling tasks.
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    Gait kinematics when learning to use a whole-body powered exoskeleton
    Park, Hanjun; Lee, Youngjae; Kim, Sunwook; Nussbaum, Maury A.; Srinivasan, Divya (SAGE, 2021-09)
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    A pilot study investigating motor adaptations when learning to walk with a whole-body powered exoskeleton
    Park, Hanjun; Kim, Sunwook; Nussbaum, Maury A.; Srinivasan, Divya (Elsevier, 2023-04-01)
    Evidence is emerging on how whole-body powered exoskeleton (EXO) use impacts users in basic occupational work scenarios, yet our understanding of how users learn to use this complex technology is limited. We explored how novice users adapted to using an EXO during gait. Six novices and five experienced users completed the study. Novices completed an initial training/familiarization gait session, followed by three subsequent gait sessions using the EXO, while experienced users completed one gait session with the EXO. Spatiotemporal gait measures, pelvis and lower limb joint kinematics, muscle activities, EXO torques, and human-EXO interaction forces were measured. Adaptations among novices were most pronounced in spatiotemporal gait measures, followed by joint kinematics, with smaller changes evident in muscle activity and EXO joint torques. Compared to the experienced users, novices exhibited a shorter step length and walked with significantly greater anterior pelvic tilt and less hip extension. Novices also used lower joint torques from the EXO at the hip and knee, and they had greater biceps femoris activity. Overall, our results may suggest that novices exhibited clear progress in learning, but they had not yet adopted motor strategies similar to those of experienced users after the three sessions. We suggest potential future directions to enhance motor adaptations to powered EXO in terms of both training protocols and human-EXO interfaces.
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    Reliability Analysis of Task Performance and Subjective Measures for Assessment of Occupational Exoskeletons
    Noll, Alexander; Nussbaum, Maury A.; Kim, Sunwook; Park, Hanjun (SAGE, 2023-10-19)
    Use of occupational exoskeletons (EXOs), an emerging intervention, has attracted great interest from various industries. To facilitate their industry adoption, emphasis has been placed on the standardization of EXO assessment, but little effort has been made to improve experimental efficiency and effectiveness. Therefore, we investigated the within-session reliability of task performance (completion time) and subjective outcome measures when using arm- and back-support EXOs during donning/doffing and cart pushing/pulling tasks. Twenty-four participants replicated 10 trials of these tasks in each of two sessions, with each participant randomly assigned to one of two EXO groups. Within-session reliability increased with the number of trials and in Session 2 (vs. Session 1). Many outcome measures achieved excellent reliability, though the number of trials required for this varied across outcome measures, tasks, and EXO types. These findings can assist in the efficient design of future studies to assess the effects of EXO use.