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Introduction: Low-back passive exoskeletons have been introduced in some manufacturing plants as personal protective equipment (PPE) to reduce the likelihood of work-related musculoskeletal disorders (WMSDs). Although previous studies have demonstrated how exoskeletons can accomplish these goals, the effects of user preference on physical and cognitive demands have not been adequately considered. The purpose of this study was to evaluate physical and cognitive responses to wearing different exoskeletons while performing simulated manufacturing tasks and examine their relationship with user preference.

Methods: Participants performed simulated manufacturing tasks for the intended use of the exoskeleton (lifting) and unrelated use (walking and drilling) without the exoskeleton and with four commercially available exoskeletons. Electromyography (EMG) sensors were placed bilaterally on the erector spinae muscle. After completing the tasks with and without each exoskeleton, the participants were asked to complete a user experience survey and the NASA TLX to evaluate cognitive and physical workload. At the end of the study, the participants were asked to rank the exoskeletons based on their preference for each specific task and overall experience.

Results:

1. Participants reported no increase in cognitive workload from wearing any of the exoskeletons, as supported by NASA-TLX scores.
2. Low-back exoskeletons reduced lumbar muscle activation when lifting. A greater reduction in muscle activation was observed when participants used their preferred exoskeleton.
3. Exoskeletons hindered the ability to perform tasks unrelated to their intended use.

Discussion: PPE must fit and function properly for each user to reduce the risk of WMSDs. Lack of coordination between the human and the exoskeleton can increase physical and cognitive demands, exposing workers to new or existing risk factors in the workplace. This study provides insight into how selecting an exoskeleton based on user preferences can influence task performance due to changes in physical and cognitive demands associated with reducing new or existing occupational risks and WMSDs.

Conclusion: Before implementing exoskeletons in manufacturing settings, it may be important to give operators different exoskeleton options and allow them to choose their preferred exoskeleton to perform tasks related to the intended purpose. Since female employment in manufacturing is at an all-time high and will likely continue to grow in the next decade, it is important to design exoskeletons that can accommodate female anthropometry. The knowledge of this research might result in better exoskeleton design and the development of new training protocols that can ensure the safety and well-being of the users.