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Book Dynamic Analysis of Astronaut Motions During Extravehicular Activity

Download or read book Dynamic Analysis of Astronaut Motions During Extravehicular Activity written by Grant Schaffner and published by . This book was released on 1995 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dynamic Analysis of Astronaut Motions in Microgravity

Download or read book Dynamic Analysis of Astronaut Motions in Microgravity written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulations of astronaut motions during extravehicular activity (EVA) tasks were performed using computational multibody dynamics methods. The application of computational dynamic simulation to EVA was prompted by the realization that physical microgravity simulators have inherent limitations: viscosity in neutral buoyancy tanks; friction in air bearing floors; short duration for parabolic aircraft; and inertia and friction in suspension mechanisms. These limitations can mask critical dynamic effects that later cause problems during actual EVA's performed in space. Methods of formulating dynamic equations of motion for multibody systems are discussed with emphasis on Kane's method, which forms the basis of the simulations presented herein. Formulation of the equations of motion for a two degree of freedom arm is presented as an explicit example. The four basic steps in creating the computational simulations were: system description, in which the geometry, mass properties, and interconnection of system bodies are input to the computer; equation formulation based on the system description; inverse kinematics, in which the angles, velocities, and accelerations of joints are calculated for prescribed motion of the endpoint (hand) of the arm; and inverse dynamics, in which joint torques are calculated for a prescribed motion. A graphical animation and data plotting program, EVADS (EVA Dynamics Simulation), was developed and used to analyze the results of the simulations that were performed on a Silicon Graphics Indigo2 computer. EVA tasks involving manipulation of the Spartan 204 free flying astronomy payload, as performed during Space Shuttle mission STS-63 (February 1995), served as the subject for two dynamic simulations. An EVA crewmember was modeled as a seven segment system with an eighth segment representing the massive payload attached to the hand. For both simulations, the initial configuration of the lower body (trunk, upper leg, and lower leg) was a neutral mi...

Book Astronaut centric Analysis of a Jetpack with Integrated Control moment Gyroscopes for Enhanced Extravehicular Activity Performance

Download or read book Astronaut centric Analysis of a Jetpack with Integrated Control moment Gyroscopes for Enhanced Extravehicular Activity Performance written by Celena Hensley Dopart and published by . This book was released on 2014 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a stepping-stone towards eventual human exploration of Mars, NASA plans to explore low-gravity objects. Since the surface environments encountered on such missions would limit the independent mobility of astronauts, a maneuvering unit that offers counter reaction forces and torques during movements and tasks will likely be required. The next-generation maneuvering and stability system proposed in this research incorporates control moment gyroscopes (CMGs) into an extravehicular activity (EVA) jetpack device currently being considered at NASA Johnson Space Center (JSC). This Mobility Augmenting Jetpack with Integrated CMGs (MAJIC) system will offer rigid attitude control not previously required for EVA tasks. This research project was designed to: (1) assess EVA task motions, astronaut dynamics, and mission concepts to support the objective comparison of the original jets-only Jetpack system and MAJIC, and (2) analyze the performance of both systems based on user evaluations of the two control configurations. An EVA task list with associated motions and tools was compiled to develop a relevant mission concept of operations that would inform the subsequent research objectives. A method for analyzing astronaut dynamics during these EVA tasks was developed and used to compare system stability of the proposed (CMG-augmented) vs. current (jets-only) control systems. The combined astronaut dynamics and controls models formed a full simulation that was integrated into a Virtual Reality (VR) environment at JSC to offer a platform for two human evaluations comparing the proposed and current control systems. Although computational analyses demonstrated increased attitude stability and decreased fuel consumption consistently across all missions and EVA tasks, results from the user evaluations were mixed. In the preliminary user evaluation, users showed overwhelming preference for MAJIC during worksite EVA tasks that incorporated astronaut motions, but no trend for piloted missions that did not incorporate astronaut motions. The results of the follow-up user evaluation indicate that benefits of MAJIC are more pronounced in certain mission scenarios, including ones in which mass and moment of inertia properties are increased (e.g. when tools are used). Future work should explore these mission scenarios further and continue development of motion capture capabilities to include full-body actuation and contact models within the virtual reality environment.

Book Masters Theses in the Pure and Applied Sciences

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this jOint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 40 (thesis year 1995) a total of 10,746 thesis titles from 19 Canadian and 144 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 40 reports theses submitted in 1995, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

Book Understanding Human space Suit Interaction to Prevent Injury During Extravehicular Activity

Download or read book Understanding Human space Suit Interaction to Prevent Injury During Extravehicular Activity written by Allison Paige Anderson and published by . This book was released on 2014 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extravehicular Activity (EVA) is a critical component of human spaceflight. Working in gas-pressurized space suits, however, causes fatigue, unnecessary energy expenditure, and injury. The problem of injury is particularly acute and is exacerbated with the additional hours astronauts spend training inside the suit, especially underwater in NASA's Neutral Buoyancy Laboratory (NBL). Although space suit performance and improved system designs have been investigated, relatively little is known about how the astronaut moves and interacts with the space suit, what factors lead to injury, and how to prevent injury. At the outset of this research effort there were no technologies suitable to evaluate human movement and contact within the space suit during dynamic movements. The objective of this thesis is to help understand human-space suit interaction and design hardware to assess and ultimately mitigate injury. This is accomplished through two specific aims. The first specific aim is to use data mining techniques to uncover trends in space suit configuration, training environment, and anthropometry, which may lead to injury. Two groups of subjects were analyzed: those whose reported shoulder injury incidence is specifically attributable to the NBL or working in the space suit, and those whose shoulder problems began in active duty, meaning working in the suit could have been a contributing factor. The first statistical model correctly identifies 39% of injured subjects, while the second model correctly identifies 68% of injured subjects. For both models, percent of training incidence in the space suit planar hard upper torso (HUT) was the most important predictor variable. Frequency of training and recovery between training were also identified as significant metrics. These variables can be monitored and modified operationally to reduce the impacts on the astronaut's health. Several anthropometric dimensions were also found to have explanatory power for injury. Expanded chest depth was included in both models, while bi-deltoid breadth was relevant for identifying injured NBL subjects and shoulder circumference was relevant for identifying injured Active subjects. These dimensions may be targeted as particularly important to accommodate in future designs of the HUT or any advanced concept space suits. Finally, for the NBL subjects, previous record of injury was found to be an important factor. Further descriptive analysis implies that analyzing the HUT style and size together may be critical for future detailed studies on fit and accommodation. These results quantitatively elucidate the underlying mechanisms of shoulder injuries for astronauts working inside the space suit. The second specific aim is to develop a wearable pressure sensing capability to quantitatively measure areas on the body's surface that the space suit impacts during normal EVA movement. A low-pressure sensing system was designed and constructed for the upper body during dynamic movements inside the space suit environment. Sensors were designed to measure between 5-60 kPa with approximately 1 kPa resolution. The sensors are constructed from hyper-elastic silicone imbedded with a microfluidic channel. The channel is filled with liquid conductive metal, galinstan, such that an applied pressure corresponds to a change in resistance of the liquid metal. The system of 12 pressure sensors accommodates anthropometry from a 50th percentile female to a 95th percentile male upper body dimensions with near shirt-sleeve mobility. The wiring was intentionally designed to achieve the best trade between flexibility, resistance, and stretch ability, but ultimately was the greatest limitation in system durability. The electronics architecture utilizes onboard data storage with more than 4 hours of use. The entire system was designed with extreme environments in mind, where considerations of shock, battery hazards, and material properties in mixed gas, pressurized atmosphere were minimized to ensure user safety. The pressure sensing system was used in a human subject experiment to characterize human-suit interaction. Three experienced subjects were asked to perform a series of 3 isolated joint movements and 2 functional tasks, all focused on upper body movement. Movements were repeated 12 times each and pressure responses were evaluated both by quantifying peak pressure and full profile responses. Comparing subjective feedback to the quantitative pressure data allows a sense of the variability of movement and minor changes in loading on the body while performing suited motions. Users generally felt they were consistent for all movements. However, using a nonparametric H-test, 53% of movements were found to be biomechanically inconsistent (p

Book Astronaut Extravehicular Activity

Download or read book Astronaut Extravehicular Activity written by Roedolph Adriaan Opperman and published by . This book was released on 2010 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Extravehicular Activity (EVA) spacesuits are a key enabling technology which allow astronauts to survive and work in the harsh environment of space. Of the entire spacesuit, the gloves may perhaps be considered the most difficult engineering design issue. A significant number of astronauts sustain hand and shoulder injuries during extravehicular activity (EVA) training and operations. In extreme cases these injuries lead to fingernail delamination (onycholysis) or rotator cuff tears and require medical or surgical intervention. In an effort to better understand the causal mechanisms of injury, a study consisting of modeling, statistical and experimental analyses was performed in section I of this thesis. A cursory musculoskeletal modeling tool was developed for use in comparing various spacesuit hard upper torso designs. The modeling effort focuses on optimizing comfort and range of motion of the shoulder joint within the suit. The statistical analysis investigated correlations between the anthropometrics of the hand and susceptibility to injury. A database of 192 male crewmembers' injury records and anthropometrics was sourced from NASA's Johnson Space Center. Hand circumference and width of the metacarpophalangeal (MCP) joint were found to be significantly associated with injuries by the Kruskal-Wallis test. Experimental testing was conducted to characterize skin blood flow and contact pressure inside the glove. This was done as part of NASA's effort to evaluate a hypothesis that fingernail delamination is caused by decreasing blood flow in the finger tips due to compression of the skin inside the extravehicular mobility unit (EMU) glove. The initial investigation consisted of a series of skin blood flow and contact pressure tests of the bare finger, and showed that blood flow decreased to approximately 60% of baseline value with increasing force, however, this occurred more rapidly for finger pads (4N) than for finger tips (ION). A gripping test of a pressure bulb using the bare hand was also performed at a moderate pressure of 13.33kPa (100mmHg) and at a high pressure of 26.66kPa (200mmHg), and showed that blood flow decreased 50% and 45%, respectively. Excessive hyperperfusion was observed for all tests following contact force or pressure, which may also contribute to the onset of delamination. Preliminary data from gripping tests inside the EMU glove in a hypobaric chamber at NASA's Johnson Space Center show that skin blood flow decreased by 45% and 40% when gripping at 3 moderate and high pressures, respectively. These tests show that finger skin blood flow is significantly altered by contact force/pressure, and that occlusion is more sensitive when it is applied to the finger pad than the finger tip. Our results indicate that the pressure on the finger pads required to articulate stiff gloves is more likely to impact blood flow than the pressure on the fingertips associated with tight or ill-fitting gloves. Improving the flexibility of the gloves will therefore not only benefit operational performance, but may also be an effective approach in reducing the incidence of finger injury. Space Policy Abstract EVA injury is only one of many dangers astronauts face in the extreme environment of space. Orbital debris presents a significant threat to astronaut safety and is a growing cause of concern. Since the dawn of satellites in the early 1950's, space debris from intentionally exploded spacecraft, dead satellites, and on-orbit collisions has significantly increased and currently outnumbers operational space hardware. Adding to this phenomenon, the advent of commercial spaceflight and the recent space activities in China and India to establish themselves as spacefairing nations are bound to accelerate the rate of space debris accumulating in low Earth orbit, thus, exacerbating the problem. The policies regulating orbital debris were drafted in the 1960s and 1970s and fail to effectively address the dynamic nature of the debris problem. These policies are not legally enforced under international law and implementation is entirely voluntary. Space debris is a relevant issue in international space cooperation. Unless regulated, some projections indicate space debris will reach a point of critical density, after which the debris will grow exponentially, as more fragments are generated by collisions than are removed by atmospheric drag. Space debris proliferation negatively impacts human spaceflight safety, presents a hazard to orbiting space assets, and may lead to portions of near-Earth orbit becoming inaccessible, thus limiting mission operations. The aim of this research effort was to review current international space policy, legislation and mitigation strategies in light of two recent orbital collision episodes. The first is the February 2009 collision between a defunct Russian Cosmos spacecraft and a commercial Iridium satellite. The second is China's display of technological prowess during the January 2007 intentional demolition of its inactive Fengyun-IC weather satellite using a SC-19 antisatellite (ASAT) missile. In each case the stakeholders, politics, policies, and consequences of the collision are analyzed. The results of this analysis as well as recommendations for alternative mitigation and regulatory strategies are presented.

Book Innovative Hand Exoskeleton Design for Extravehicular Activities in Space

Download or read book Innovative Hand Exoskeleton Design for Extravehicular Activities in Space written by Pierluigi Freni and published by Springer. This book was released on 2014-06-23 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Space Station Systems

Download or read book Space Station Systems written by and published by . This book was released on 1987 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Research and Technology Program Digest

Download or read book Research and Technology Program Digest written by United States. National Aeronautics and Space Administration and published by . This book was released on with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Technology for Large Space Systems A Bibliography with Indexes supplement 20

Download or read book Technology for Large Space Systems A Bibliography with Indexes supplement 20 written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Division and published by . This book was released on 1989 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Research and Technology Program Digest Flash Index

Download or read book Research and Technology Program Digest Flash Index written by and published by . This book was released on 1967 with total page 794 pages. Available in PDF, EPUB and Kindle. Book excerpt: