Innovative Hand Exoskeleton Design For Extravehicular Activities In Space

Environmental conditions and pressurized spacesuits expose astronauts to problems of fatigue during lengthy extravehicular activities, with adverse impacts especially on the dexterity, force and endurance of the hands and arms. A state-of-the-art exploration in the field of hand exoskeletons revealed that available products are unsuitable for space applications because of their bulkiness and mass. This book proposes a novel approach to the development of hand exoskeletons, based on an innovative soft robotics concept that relies on the exploitation of electroactive polymers operating as sensors and actuators, on a combination of electromyography and mechanomyography for detection of the user’s will and on neural networks for control. The result is a design that should enhance astronauts’ performance during extravehicular activities. In summary, the advantages of the described approach are a low-weight, high-flexibility exoskeleton that allows for dexterity and compliance with the user’s will.

This book describes the development of portable, wearable, and highly customizable hand exoskeletons to aid patients suffering from hand disabilities. It presents an original approach for the design of human hand motion assistance devices that relies on (i) an optimization-based kinematic scaling procedure, which guarantees a significant adaptability to the user’s hands motion, and (ii) a topology optimization-based design methodology, which allowed the design of a lightweight, comfortable device with a high level of performance. The book covers the whole process of hand exoskeleton development, from establishing a new design strategy, to the construction and testing of hand exoskeleton prototypes, using additive manufacturing techniques. As such, it offers timely information to both researchers and engineers developing human motion assistance systems, especially wearable ones.

The empirical investigation of extravehicular activity (EVA) mass handling conducted on NASA's Precision Air-Bearing Floor led to a Phase I SBIR from JSC. The purpose of the SBIR was to design an innovative system for evaluating space suit mobility and stability in conditions that simulate EVA on the surface of the Moon or Mars. The approach we used to satisfy the Phase I objectives was based on a structured methodology for the development of human-systems technology. Accordingly the project was broken down into a number of tasks and subtasks. In sequence, the major tasks were: 1) Identify missions and tasks that will involve EVA and resulting mobility requirements in the near and long term; 2) Assess possible methods for evaluating mobility of space suits during field-based EVA tests; 3) Identify requirements for behavioral evaluation by interacting with NASA stakeholders;.4) Identify necessary and sufficient technology for implementation of a mobility evaluation system; and 5) Prioritize and select technology solutions. The work conducted in these tasks is described in this final volume of the series on EVA mass handling. While prior volumes in the series focus on novel data-analytic techniques, this volume addresses technology that is necessary for minimally intrusive data collection and near-real-time data analysis and display.McDonald, P. Vernon and Newman, DavaJohnson Space CenterDATA ACQUISITION; REAL TIME OPERATION; EXTRAVEHICULAR ACTIVITY; FIELD TESTS; SPACE SUITS; STABILITY; MOON; GAS BEARINGS

The objective was to assess the effects of extravehicular activity (EVA) gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that with EVA gloves strength is reduced by nearly 50 percent, there is a considerable reduction in dexterity, performance decrements increase with increasing pressure differential, and some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed. Bishu, Ram R. and Klute, Glenn Johnson Space Center...