Engineering topics
Jarvis, Sarah
Publications and source records attributed to Jarvis, Sarah.
Estimation of Preferred Work Envelope from Simulated Functional Tasks in a Spacesuit
Spacesuits allow humans to function in an incredibly harsh environment. However, they introduce some restrictions to human capabilities. In general, crewmembers in a spacesuit have a restricted maximal reach envelope, reduced field of view, and reduced tactility. When tasks and interfaces are being designed, they need to take into account the restrictions associated with working in an Extravehicular Activity (EVA) suit.
Development of Human-Spacesuit Interaction Models
Today’s astronaut corps represents a wide range of various anthropometric dimensions. Accommodating this wide range of anthropometry and protecting for size variations in future crews, makes spacesuit sizing and fit a challenging and necessary aspect of suit development. Spacesuit fit can play an important role in performance, but a suit fit assessment, especially in dynamic postures, is difficult without extensive human-in-the-loop testing. One approach to address this issue is to model and simulate the human-spacesuit interactions for a target population early in the design process. The Anthropometry and Biomechanics Facility (ABF) at the NASA Johnson Space Center has been working to incorporate parametric human models based on 3D full-body scan data with spacesuit CAD models that can be driven by the user or imported motion capture data. An articulated spacesuit model combined with a poseable high-fidelity human model allows comparisons to be made between spacesuit capabilities and normal human ranges of motion. Furthermore, predictions can be made as to how a specific individual or population may perform in the suit from the perspective of reach and mobility. In this paper, we will present case study examples of reach, mobility, and fit analyses that can be done with these models and the methodology developed thus far. These models have the potential to become powerful tools for evaluating future spacesuit design architectures from the perspective of optimizing fit and performance.
Test Bed for Human Performance in Mockup Suit
Crewmembers' ability to adjust to changes in gravity and sensorimotor function is essential for successful suited mobility in lunar and planetary missions. Setups for current pressurized spacesuit testing require suit technicians, specialized medical clearances, and test support personnel along with increased risk to the subject. Furthermore, suited setups constrain the types of additional hardware that can be used. A test bed was developed with the goal to evaluate human suited performance using an unpressurized Mark III mockup suit and virtual reality (VR) system.
Development of Underwater Motion Capture System for Space Suit Mobility Assessment
No abstract available
Assessment of Suited Reach Envelope in an Underwater Environment
Predicting the performance of a crewmember in an extravehicular activity (EVA) space suit presents unique challenges. The kinematic patterns of suited motions are difficult to reproduce in gravity. Additionally, 3-D suited kinematics have been practically and technically difficult to quantify in an underwater environment, in which crewmembers are commonly trained and assessed for performance. The goal of this study is to develop a hardware and software system to predictively evaluate the kinematic mobility of suited crewmembers, by measuring the 3-D reach envelope of the suit in an underwater environment. This work is ultimately aimed at developing quantitative metrics to compare the mobility of the existing Extravehicular Mobility Unit (EMU) to newly developed space suit, such as the Z-2. The EMU has been extensively used at NASA since 1981 for EVA outside the Space Shuttle and International Space Station. The Z-2 suit is NASA's newest prototype space suit. The suit is comprised of new upper torso and lower torso architectures, which were designed to improve test subject mobility.
EVA Human Health and Performance Benchmarking Study Overview and Development of a Microgravity Protocol
The primary objective of this study is to develop a protocol to reliably characterize human health and performance metrics for individuals working inside various EVA suits under realistic spaceflight conditions. Expected results and methodologies developed during this study will provide the baseline benchmarking data and protocols with which future EVA suits and suit configurations (e.g., varied pressure, mass, center of gravity [CG]) and different test subject populations (e.g., deconditioned crewmembers) may be reliably assessed and compared. Results may also be used, in conjunction with subsequent testing, to inform fitness-for-duty standards, as well as design requirements and operations concepts for future EVA suits and other exploration systems.
A Parametric Model of Shoulder Articulation for Virtual Assessment of Space Suit Fit
Shoulder injury is one of the most severe risks that have the potential to impair crewmembers' performance and health in long duration space flight. Overall, 64% of crewmembers experience shoulder pain after extra-vehicular training in a space suit, and 14% of symptomatic crewmembers require surgical repair (Williams & Johnson, 2003). Suboptimal suit fit, in particular at the shoulder region, has been identified as one of the predominant risk factors. However, traditional suit fit assessments and laser scans represent only a single person's data, and thus may not be generalized across wide variations of body shapes and poses. The aim of this work is to develop a software tool based on a statistical analysis of a large dataset of crewmember body shapes. This tool can accurately predict the skin deformation and shape variations for any body size and shoulder pose for a target population, from which the geometry can be exported and evaluated against suit models in commercial CAD software. A preliminary software tool was developed by statistically analyzing 150 body shapes matched with body dimension ranges specified in the Human-Systems Integration Requirements of NASA ("baseline model"). Further, the baseline model was incorporated with shoulder joint articulation ("articulation model"), using additional subjects scanned in a variety of shoulder poses across a pre-specified range of motion. Scan data was cleaned and aligned using body landmarks. The skin deformation patterns were dimensionally reduced and the co-variation with shoulder angles was analyzed. A software tool is currently in development and will be presented in the final proceeding. This tool would allow suit engineers to parametrically generate body shapes in strategically targeted anthropometry dimensions and shoulder poses. This would also enable virtual fit assessments, with which the contact volume and clearance between the suit and body surface can be predictively quantified at reduced time and cost.
A Parametric Model of Shoulder Articulation for Virtual Assessment of Space Suit Fit
Suboptimal suit fit is a known risk factor for crewmember shoulder injury. Suit fit assessment is however prohibitively time consuming and cannot be generalized across wide variations of body shapes and poses. In this work, we have developed a new design tool based on the statistical analysis of body shape scans. This tool is aimed at predicting the skin deformation and shape variations for any body size and shoulder pose for a target population. This new process, when incorporated with CAD software, will enable virtual suit fit assessments, predictively quantifying the contact volume, and clearance between the suit and body surface at reduced time and cost.
A Parametric Model of Shoulder Articulation for Virtual Assessment of Space Suit Fit
Goal of space human factors analyses: Place the highly variable human body within these restrictive physical environments to ensure that the entire anticipated population can live, work, and interact. Space suits are a very restrictive space and if not properly sized can result in pain or injury. The highly dynamic motions performed while wearing a space suit often make it difficult to model. Limited human body models do not have much allowance for customization of anthropometry and representation of the population that may wear a space suit.