Evaluating human-extravehicular activity suit injury using wearable sensors

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.Cataloged from PDF version of thesis.Includes bibliographical references (pages 81-82).All the current flown spacesuits are gas pressurized and require astronauts to exert a substantial amount of energy in order to move the suit into a desired position. The pressurization of the suit therefore limits human mobility, causes discomfort, and leads to a variety of contact and strain injuries. While suit-related injuries have been observed for many years and some basic countermeasures have been implemented, there is still a lack of understanding of how humans move within the spacesuit. The rise of wearable technologies is changing the paradigm of biomechanics and allowing a continuous monitoring of motion performance in fields like athletics or medical rehabilitation. Similarly, pressure sensors allow a sensing capability to better locate the areas and magnitudes of contact between the human and their interface and reduce the risk of injuries. Coupled together these sensors allow a better understanding of the complex interactions between the astronaut and his suit, enhance astronauts performance through a real time monitoring and reducing the risk of injury. The first set of objectives of this research are: to gain a greater understanding of this human-spacesuit interaction and potential for injury by analyzing the suit-induced pressures against the body, to determine the validity of the particular sensors used with suggested alternatives, and to extend the wearable technology application to other relatable fields such as soldier armor and protective gear. An experiment was conducted in conjunction with David Clark Incorporated Company on the Launch Entry Development spacesuit analyzing the human-spacesuit system behavior for isolated and functional upper body movement tasks: elbow flexion/extension, shoulder flexion/extension, shoulder abduction/adduction and cross body reach, which is a complex succession of critical motions for astronaut and pilot task. The contact pressure between the person and the spacesuit was measured by three low-pressure sensors (the Polipo) over the arm, and one high-pressure sensor located on the shoulder (Novel). The same sensors were used in a separate experiment conducted in conjunction with Protect the Force Company on several different United States Marine Corps (USMC) protective gear configurations, which analyzed the human-gear interactions for: shoulder flexion/extension, horizontal shoulder abduction/adduction, vertical shoulder abduction/adduction, and the cross body reach. Findings suggest that as suit pressurization increases, contact pressure across the top of the shoulder increases for all motion types. While it proved to be a perfectly acceptable method for gathering shoulder data, improvements can be made on the particular sensors used and the type of data collected and analyzed. In the future, human-suit interface data can be utilized to influence future gas-pressurized spacesuit design. Additionally, this thesis briefly explores the incompatibilities between Russian and U.S. EVA capabilities in order to make a case for equipment standardization.by Sabrina Reyes.S.M