Pressure and kinematic in-suit sensors: Assessing human-suit interaction for injury risk mitigation

With NASA's current trajectory under the Commercial Crew program, spacesuits will become a critical system for the successful implementation of commercial orbital transportation services (COTS). 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 objective of this research is to gain a greater understanding of this human-spacesuit interaction and potential for injury by analyzing the suit-induced pressures against the body along with joint kinematics of how astronauts move inside the space suit. 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 an in-suit sensing capability to better locate the areas of contact between the human and the suit 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 astronaut's performance through a real time monitoring and reducing the risk of injury. An experiment was conducted in conjunction with David Clark Incorporated Company on the Launch Entry Development spacesuit. The experiment analyzed the mobility and human-spacesuit system behavior for isolated and functional upper body movement tasks, with each motion repeated 15 times: 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 a high-pressure sensor located on the shoulder (Novel). Joint angles were measured internally and externally to the suit with 6 inertial measurement units (Opal IMUs): three external and three internal. The spacesuit was tested in its natural recumbent position. The analysis of the mobility of the spacesuit, and the interactions between the suit and the person are analyzed and conclusion and recommendations are given.