xEMU Lower Torso Assembly (LTA) Brief Fleet Sizing Study
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The Exploration Extravehicular Mobility Unit (xEMU) project is tasked with building a spacesuit for the lunar 2024 missions. These missions will require a mobile Lower Torso Assembly (LTA) to fit the required range of astronauts’ anthropometry with optimal mobility. The goal of this work is to predict the proportion of the current and projected crew population accommodated by the new LTA design. Initially, virtual fit checks were conducted via CAD modeling. Body shape manikins were iteratively positioned inside the CAD geometry. The resultant suit-to-body contact and overlap was quantified and used to develop a statistical model to predict the probability of fit. Twenty test subjects whose predicted fit is at a borderline level are currently being assessed. The subjects don/doff a 3D printed LTA mockup, and perform basic functional movements, including walking, kneeling and squatting. 3D scans are recorded, and a questionnaire is administered for the overall fit and any discomfort locations. The statistical model will be updated using the physical test outcome and projected to a large database of approximately 2000 male and 1000 female body shapes from the US Army. The model will estimate the overall proportion of the accommodated population to characterize the anthropometry of the crew who would fit in the LTA. This will determine if the current LTA sizing is adequate to meet the xEMU requirements.