Browsing by Author "McFarland, Shane M."
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Item Feasibility Assessment of an Extravehicular Activity Glove Sensing Platform to Evaluate Potential Hand Injury Risk Factors(45th International Conference on Environmental Systems, 2015-07-12) Reid, Christopher R.; McFarland, Shane M.Injuries to the hands are common among astronauts who train for extravehicular activity. When the gloves are pressurized, they restrict movement and create pressure points during tasks, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally more severe injuries such as onycholysis. A brief review of NASA’s Lifetime Surveillance of Astronaut Health’s injury database reveals that 76% of astronaut hand and arm injuries from training between 1993 and 2010 occurred either to the fingernail, finger crotch, metacarpophalangeal joint, or fingertip. The purpose of this study was to assess the potential of using small sensors to measure forces acting on the fingers and hand within pressurized gloves and other variables such as blood perfusion, skin temperature, humidity, fingernail strain, and skin moisture, among others. Tasks were performed gloved and ungloved in a pressurized glove box. The test demonstrated that fingernails experienced greater transverse strain levels for tension or compression than for longitudinal strain, even during axial fingertip loading. Blood perfusion peaked and dropped as the finger deformed during finger presses, indicating an initial dispersion and decrease of blood perfusion levels. Force- sensitive resistors to force plate comparisons showed similar force curve patterns as fingers were depressed, indicating suitable functionality for future testing. Strategies for proper placement and protection of these sensors for ideal data collection and longevity through the test session were developed and will be implemented going forward for future testing.Item A Novel Method for Characterizing Spacesuit Mobility Through Metabolic Cost(44th International Conference on Environmental Systems, 2014-07-13) McFarland, Shane M.; Norcross, Jason R.Historically, spacesuit mobility has been characterized by directly measuring both range of motion and joint torque of individual anatomic joints. The work detailed herein aims to improve on this method, which is often prone to uncertainly, lack of repeatability, and a general lack of applicability to real-world functional tasks. Specifically, the goal of this work is to characterize suited mobility performance by directly measuring the metabolic performance of the occupant. Pilot testing was conducted in 2013, employing three subjects performing a range of functional tasks in two different suits prototypes, the Mark III and Z-1. Cursory analysis of the results shows the approach has merit, with consistent performance trends toward one suit over the other. Forward work includes the need to look at more subjects, a refined task set, and another suit in a different mass/mobility regime to validate the approach.Item Spacesuit Glove-Induced Hand Trauma and Analysis of Potentially Related Risk Variables(45th International Conference on Environmental Systems, 2015-07-12) Charvat, Jacqueline M.; Norcross, Jason; Reid, Christopher R.; McFarland, Shane M.Injuries to the hands are common among astronauts who train for extravehicular activity (EVA). When the gloves are pressurized, they restrict movement and create pressure points during task work, sometimes resulting in pain, muscle fatigue, abrasions, and occasionally more severe injuries such as onycholysis. Glove injuries, both anecdotal and recorded, have been reported during EVA training and flight persistently through NASA’s history regardless of mission or glove model. Theories as to causation such as glove-hand fit are common but often lacking in supporting evidence. Previous statistical analysis has evaluated onycholysis in the context of crew anthropometry only. The purpose of this study was to analyze all injuries (as documented in the medical records) and available risk factor variables with the goal to determine engineering and operational controls that may reduce hand injuries due to the EVA glove in the future. A literature review and data mining study were conducted between 2012 and 2014. This study included 179 US NASA crew members who trained or completed an EVA between 1981 and 2010 (crossing both Space Shuttle and International Space Station eras) and wore either the 4000 Series or the Phase VI glove during Extravehicular Mobility Unit spacesuit EVA training and flight. All injuries recorded in medical records were analyzed in their association to candidate risk factor variables. Those risk factor variables included demographic characteristics, hand anthropometry, glove fit characteristics, and EVA training/flight characteristics. Using literature, medical records, and anecdotal causation comments recorded in crew member injury data, investigators were able to identify several risk factors associated with increased risk of glove related injuries. Prime among those risk factors were smaller hand anthropometry, duration of individual suited exposures, and improper glove-hand fit as calculated by the difference in the anthropometry middle finger length compared to the baseline EVA glove middle finger length.