Lauren Harvill

An Ergonomic Evaluation of the Extravehicular Mobility Unit (EMU) Spacesuit Hard Upper Torso (HUT) Size Effect on Mobility, Strength, and Metabolic Performance

Introduction: The objective of this project was to develop a comprehensive methodology to assess the suit fit and performance differences between a nominally sized extravehicular mobility unit (EMU) spacesuit and a nominal +1 (plus) sized EMU. Method: This study considered a multitude of evaluation metrics including 3D clearances and pressure point mapping to quantify potential issues associated with using off-nominal suit sizes. Results: There were minimal differences with using a plus suit size. Discussion: Analysis of the results indicates that future suit size evaluations should consider this ergonomic approach to understand and mitigate potential suit fit and performance issues.

Development of Underwater Motion Capture System for Space Suit Mobility Assessment

The objective of this study was to develop and deploy a novel motion capture system that utilizes off-the-shelf, dive-rated hardware to measure 3-D whole body reach envelopes of space suits in an underwater analog, which simulates a microgravity environment. The accuracy of the developed system was compared to a gold standard motion capture system in a dry-land condition before deployment. This study is ultimately aimed at providing a methodology for quantitative metrics to evaluate and compare the mobility performances of a newly developed prototype space suit versus an existing space suit at the Neutral Buoyancy Laboratory (NBL) at NASA’s Johnson Space Center.

Evaluating Suit Fit Using Performance Degradation

The Mark III planetary technology demonstrator space suit can be tailored to an individual by changing the modular components of the suit, such as the arms, legs, and gloves, as well as adding or removing sizing inserts in key areas. A method was sought to identify the transition from an ideal suit fit to a bad fit and how to quantify this breakdown using a metric of mobility-based human performance data. To this end, the degradation of the range of motion of the elbow and wrist of the suit as a function of suit sizing modifications was investigated to attempt to improve suit fit. The sizing range tested spanned optimal and poor fit and was adjusted incrementally to compare each joint angle across five different sizing configurations. Suited range of motion data were collected using a motion capture system for nine isolated and functional tasks utilizing the elbow and wrist joints. A total of four subjects were tested with motions involving both arms simultaneously as well as the right arm by itself. Findings indicated that no single joint drives the performance of the arm as a function of suit size; instead it is based on the interaction of multiple joints along a limb. To determine a size adjustment range where an individual can operate the suit at an acceptable level, a performance detriment limit was set. This user-selected limit reveals the task-dependent tolerance of the suit fit around optimal size. For example, the isolated joint motion indicated that the suit can deviate from optimal by as little as -0.6 in to -2.6 in before a 10% performance drop occurs in the wrist or elbow joint. This study identified a preliminary method to quantify the impact of size on performance and developed a new way to gauge tolerances around optimal size.