Innovative Hand Exoskeleton Design for Extravehicular Activities in Space
Innovative Hand Exoskeleton Design for Extravehicular Activities in Space

Author: Pierluigi Freni

Publisher: Springer

Published: 2014-06-23

Total Pages: 98

ISBN-13: 331903958X

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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.

An Unpowered Exoskeleton to Reduce Astronaut Hand Fatigue During Microgravity EVA
An Unpowered Exoskeleton to Reduce Astronaut Hand Fatigue During Microgravity EVA

Author: Alan John Carey

Publisher:

Published: 2016

Total Pages:

ISBN-13: 9781369202564

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Astronaut hand fatigue during Extravehicular Activity (EVA) and EVA training is a critical risk in human space exploration. Improved glove designs over the past forty years have reduced hand fatigue, but limitations of the technology prevent major improvements to reduce hand fatigue. Therefore, a mechanism to assist astronauts by reducing hand fatigue was explored. Many organizations have already developed exoskeletons to assist astronauts, but all mechanisms developed required electrically powered actuators and control systems to enhance grip strength. However, astronauts already possess the strength required to actuate the glove; what is needed is a method to reduce fatigue without introducing electromechanical complexity. A passive mechanical system was developed as a proof-of-concept to test the feasibility of an unpowered exoskeleton to maintain static grip around an object. The semi- rigid nature of an inflated pressure glove provided an ideal substrate to mount a mechanism and associated components to allow an astronaut to release his/her grip inside the glove while maintaining attitude, as the mechanism will keep the glove closed around an object.Three prototypes were fabricated and tested to evaluate the architecture. The final two prototypes were tested on a real pressure suit glove at Final Frontier Design (FFD), and the third mechanism demonstrated attachment and basic operating principles. At University of California (UC) Davis, pressure glove analogs were fabricated from a baseball batting glove and polystyrene to simulate a real pressure glove without the risk of testing in a reduced pressure environment (i.e. a glove box). Testing of the third prototype showed a reduction in fatigue as measured by Maximum Voluntary Contraction (MVC) grip force over a 30 second period when the mechanism assisted gripping an object.

Space Suit Simulator for Partial Gravity Extravehicular Activity Experimentation and Training
Space Suit Simulator for Partial Gravity Extravehicular Activity Experimentation and Training

Author: Andrea Lynn Gilkey

Publisher:

Published: 2012

Total Pages: 121

ISBN-13:

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During human space exploration, mobility is extremely limited when working inside a pressurized space suit. Astronauts perform extensive training on Earth to become accustomed to space suit-imposed high joint torques and limited range of motion. Space suit experimentation is difficult for researchers because the current suit is expensive, bulky, heavy, hard to don/doff, and in very short supply. The main objective of this thesis is to develop a wearable space suit simulator (S3) exoskeleton that can mimic the joint torques and reduced mobility of various pressurized space suit designs. A space suit simulator exoskeleton is a novel method for simulating joint torques while offering a lightweight, portable, and easily accessible design. This thesis describes early work towards development of the S3 exoskeleton. A space suit joint database was developed, which includes joint torque and angle range of motion information for multiple pressurized space suits, degrees of freedom, and pressurization levels. The space suit joint database was used to set the joint torque and angle range of motion requirements for the S3 exoskeleton. Additionally, various actuators that have been used in previous exoskeleton designs were compared according to weight and bulk characteristics to select actuators for the S3 exoskeleton. The conceptual designs of the S3 knee and hip components are presented. Finally, the S3 computer simulation is described, which allows users to input the geometries and locations of the S3 exoskeleton components. The computer simulation outputs the space suit hysteresis curves to compare S3 joint design performance to actual space suit performance. Feasible design solutions for the S3 exoskeleton joints can be determined from designs that minimize the root-mean-square error of the hysteresis curves.

Engineering a Robotic Exoskeleton for Space Suit Simulation
Engineering a Robotic Exoskeleton for Space Suit Simulation

Author: Forrest Edward Meyen

Publisher:

Published: 2013

Total Pages: 182

ISBN-13:

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Novel methods for assessing space suit designs and human performance capabilities are needed as NASA prepares for manned missions beyond low Earth orbit. Current human performance tests and training are conducted in space suits that are heavy and expensive, characteristics that constrain possible testing environments and reduce suit availability to researchers. Space suit mock-ups used in planetary exploration simulations are light and relatively inexpensive but do not accurately simulate the joint stiffness inherent to space suits, a key factor impacting extravehicular activity performance. The MIT Man-Vehicle Laboratory and Aurora Flight Sciences designed and built an actively controlled exoskeleton for space suit simulation called the Extravehicular Activity Space Suit Simulator (EVA S3), which can be programmed to simulate the joint torques recorded from various space suits. The goal of this research is to create a simulator that is lighter and cheaper than a traditional space suit so that it can be used in a variety of testing and training environments. The EVA S3 employs pneumatic actuators to vary joint stiffness and a pre-programmed controller to allow the experimenter to apply torque profiles to mimic various space suit designs in the field. The focus of this thesis is the design, construction, integration, and testing of the hip joint and backpack for the EVA S3. The final designs of the other joints are also described. Results from robotic testing to validate the mechanical design and control system are discussed along with the planned improvements for the next iteration of the EVA S3. The fianl EVA S3 consists of a metal and composite exoskeleton frame with pneumatic actuators that control the resistance of motion in the ankle, knee, and hip joints, and an upper body brace that resists shoulder and elbow motions with passive spring elements. The EVA S3 is lighter (26 kg excluding the tethered components) and less expensive (under $600,000 including research, design, and personnel) than a modem space suit. Design adjustments and control system improvements are still needed to achieve a desired space suit torque simulation fidelity within 10% root-mean-square error.

Development and Testing of Hand Exoskeletons
Development and Testing of Hand Exoskeletons

Author: Matteo Bianchi

Publisher: Springer Nature

Published: 2020-02-05

Total Pages: 107

ISBN-13: 3030376850

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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.

sEMG-based Control Strategy for a Hand Exoskeleton System
sEMG-based Control Strategy for a Hand Exoskeleton System

Author: Nicola Secciani

Publisher: Springer Nature

Published: 2021-11-22

Total Pages: 103

ISBN-13: 3030902838

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This book reports on the design and testing of an sEMG-based control strategy for a fully-wearable low-cost hand exoskeleton. It describes in detail the modifications carried out to the electronics of a previous prototype, covering in turn the implementation of an innovative sEMG classifier for predicting the wearer's motor intention and driving the exoskeleton accordingly. While similar classifier have been widely used for motor intention prediction, their application to wearable device control has been neglected so far. Thus, this book fills a gap in the literature providing readers with extensive information and a source of inspiration for the future design and control of medical and assistive devices.