Integrative Fit Assessments for Multi-Component Stack-Up of xEMU
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Sufficient mobility, proper fit, and adequate comfort are critical design goals for the Exploration Extravehicular Mobility Unit (xEMU), NASA�s next generation spacesuit. While component-wise fit assessments can provide baseline information, the wearers� experience might be different when multiple components are stacked and integrated together. This study is concerned with the fit, comfort, and mobility associated with the stack-up of the Hard Upper Torso (HUT), Lower Torso Assembly (LTA) and other interconnecting components. The first aim of this study was to identify the sizing ring configuration preferred by wearers of different body shapes and sizes. Sizing rings are inserts placed between the Body Seal Closure of the HUT and the waist bearing. Sizing rings of different heights can be combined to accommodate the wearer�s torso size. Human test subjects wore the stack-up of 3D printed mockups and performed prescribed functional EVA postures as they were surveyed for feedback on fit and comfort. The second aim was to assess the effect of elongating the brief height by 50.8 mm, instead of using a same height sizing ring. The hypothetical benefit was a closer alignment of the mechanical pivot point of the brief with the anatomical low back joint center, especially for wearers with a longer torso. Human-in-the-loop testing was performed to compare the baseline and elongated brief configurations, with a focus on mobility and comfort differences. Based on the test outcome, a statistical model is currently in development to predict the optimal sizing ring and brief configuration as a function of the wearer�s anthropometry. This study can also help to determine the largest and smallest body sizes in crew populations that can be accommodated with the HUT-to-LTA stack-up, with increased mobility and comfort.