Comparison of 3D Photogrammetric and Laser Hand Scans to Manual Measurement Methods for EVA Glove Fabrication

Spacesuits are critical to human survival and exploration outside of the Earth's protective environment. A number of environmental variables must be considered when designing a protective suit, which vary by location: Low Earth Orbit (LEO), Lunar Surface, or Mars Surface. Common to all the environments is the importance of a well-fitting suit, including gloves, in order to effectively and safely conduct EVA operations. During the Mercury, Gemini, Apollo, and Skylab programs, astronauts wore customized pressure suits and gloves. During the Shuttle era, astronauts were allocated to one of five general suit sizes: XS, S, M, L, and XL which were eventually reduced to 2 or 3 sizes. Shuttle EVA gloves varied between re-flight of standard sizes, to customized gloves. In spite of the customization of current EVA gloves, astronauts on the International Space Station (ISS) can experiencing strength degradation of over 50%, and many are experiencing finger injuries, including the loss of fingernails. The lack of significant performance improvement with current customization is confounding and the cause of the injuries are still largely unknown. Our objective is perform research to better understand the current “Fit” problems, which we believe will lead to customized suits and gloves which are designed to improve overall performance: enhance dexterity, reduce strength requirements, and minimize fatigue while still satisfying both thermal and micro-meteoroid requirements. Although many industries (e.g. aeronautics, automobile and apparel) are moving towards Digital Human Modelling (DHM) in order to design and fabricate with Finite Element Analyses (FEA), customization of current Phase VI gloves still generally begins with a manual measurement of each crew member's hands in accordance with NASA Human Factor's standards, followed by a mold casting which is scanned and measured. Manufacture of each glove is labor intensive. As far as the authors can determine, no dynamic digital analyses has been made of different hand configurations to characterize changes in measurements in order to design a glove with optimized fit from finger extension to tool grasp. In order to accomplish a future vision of scanning a hand in motion followed by rapid prototyping of a functionally optimized EVA glove, the Texas A&M University (TAMU) Aerospace Human Systems Laboratory (AHSL) recently acquired a 3dMD 3D Motion Capture system configured to capture 20 seconds of hand motion or 200 frames. While the final goal will be to develop digital scans which can be converted to FEA models, complete with skin properties, the objective of this paper is to report the results of comparing manual anthropometric hand measurements with those produced through the digital imaging of the 3dMD system and the results of converting the digital file into a 3D printed hand which replicates both the manual and 3dMD measurements. We are also exploring digital images with the Vitus Laser System. Initial results indicate that motion capture digital images may be used to accurately determine dimensional changes in a hand which provides a positive step towards DHM of the hand/EVA glove combination.