Download or read book Design of Soft Knee Exoskeleton and Modeling Effects of Variable Stiffness for Advanced Space Suits and Planetary Exploration written by Allison Paige Porter and published by . This book was released on 2020 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Existing gas-pressurized space suit designs aim to provide astronauts with a wide range of joint motion while minimizing joint torque during extra-vehicular activity (EVA). However, current space suits have stiff joints with limited range, which impede performance. Future designs should consider that some joint torque can be beneficial in storing elastic energy for locomotion in reduced gravity planetary EVAs. Though current gas-pressurized space suits restrict astronaut movement, they are capable of partially supporting their own mass and storing elastic energy in the lower body, allowing metabolic cost reduction during locomotion in reduced gravity, such as on Mars or the moon. The BioSuit[superscript TM] developed by the Massachusetts Institute of Technology (MIT), is an advanced, skin-tight compression garment concept, which exerts mechanical counterpressure (MCP) directly on the astronaut’s skin with the benefits of increasing range of motion and performance while also reducing mass when compared to gas-pressurized space suits. A BioSuit[superscript TM] soft knee exoskeleton with tunable knee stiffness was developed to minimize metabolic expenditure during locomotion in partial gravity and maximize mobility. Musculoskeletal modeling simulated predicted soft knee exoskeleton stiffness at the knee during walking in Earth and Lunar gravity. This thesis summarizes the design and development of prototype actuation in a soft exoskeleton in collaboration with the D-Air Lab (Vicenza, Italy) that applies variable knee stiffness. Soft knee exoskeleton design criteria, fabrication techniques, and simulated impacts on joint kinematics and metabolic cost are discussed. The soft knee exoskeleton was shown to exert tunable knee stiffness via airbags. Prototypes were developed to minimize partial gravity locomotion metabolic cost and space suit inflexibility. An OpenSim software pipeline was shown to be capable of torsional spring stiffness modeling at the knee analogous with predicted soft knee exoskeleton stiffness. Integration of 1G and 0.17G walking data enabled comparison of energetics trends between exoskeleton conditions within each gravity level. The results of this thesis demonstrate the ability to integrate a soft knee exoskeleton into the BioSuit[superscript TM] to improve space suit design and enable longer, safer, and more complex EVAs in partial gravity.
Download or read book Space Exploration Challenges written by Bradley Thomas Holschuh and published by . This book was released on 2010 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses two challenges associated with advanced space and planetary exploration: characterizing and improving the mobility of current and future gas pressurized space suits; and developing effective domestic Planetary Protection policies for the emerging private space industry. Gas-pressurized space suits are known to be highly resistive to astronaut movement. As NASA seeks to return to planetary exploration, there is a critical need to improve full body space suit mobility for planetary exploration. Volume effects (the torque required to displace gas due to internal volume change during movement) and structural effects (the additional torque required to bend the suit materials in their pressurized state) are cited as the primary contributors to suit rigidity. Constant volume soft joints have become the design goal of space suit engineers, and simple joints like the elbow are believed to have nearly achieved such performance. However, more complex joints like the shoulder and waist have not yet achieved comparable optimization. As a result, it is hypothesized that joints like the shoulder and waist introduce a third, and not well studied, contributor to space suit rigidity: pressure effects (the additional work required to compress gas in the closed operating volume of the suit during movement). This thesis quantifies the individual contributors to space suit rigidity through modeling and experimentation. An Extravehicular Mobility Unit (EMU) space suit arm was mounted in a -30kPa hypobaric chamber, and both volume and torque measurements were taken versus elbow angle. The arm was tested with both open and closed operating volumes to determine the contribution of pressure effects to total elbow rigidity. These tests were then repeated using a full EMU volume to determine the actual impact of elbow pressure effects on rigidity when connected to the full suit. In both cases, structural and volume effects were found to be primary contributors to elbow joint rigidity, with structural effects dominating at low flexion angles and volume effects dominating at high flexion angles; pressure effects were detected in the tests that used only the volume of the arm, but were found to be a secondary contributor to total rigidity (on average 5%). These pressure effects were not detected in the tests that used the volume representative of a full EMU. Unexpected structural effects behavior was also measured at high ( 75°) flexion angles, suggesting that the underlying mechanisms of these effects are not yet fully understood, and that current models predicting structural effects behavior do not fully represent the actual mechanisms at work. The detection of pressure effects in the well-optimized elbow joint, even if only in a limited volume, suggests that these effects may prove significant for sub-optimized, larger, multi-axis space suit joints. A novel, fast-acting pressure control system, developed in response to these findings, was found to be capable of mitigating pressure spikes due to volume change (and thus, pressure effects). Implementation of a similar system in future space suit designs could lead to improvements in overall suit mobility. A second study, which focused on the implications of the development of the US private space industry on domestic Planetary Protection policy, is also presented. As signatories of the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space (commonly known as the Outer Space Treaty), the United States is responsible for implementing Planetary Protection procedures designed to prevent biological contamination of the Solar System, as well as contamination of the Earth by any samples returned from extra-terrestrial bodies. NASA has established policies and procedures to comply with this treaty, and has successfully policed itself independently and autonomously since the signing of the treaty. However, for the first time in the history of the American space program, private entities outside of NASA have developed the capability and interest to send objects into space and beyond Earth orbit, and no current protocol exists to guarantee these profit-minded entities comply with US Planetary Protection obligations (a costly and time-consuming process). This thesis presents a review of US Planetary Protection obligations, including NASA's procedures and infrastructure related to Planetary Protection, and based on these current protocols provides policy architecture recommendations for the emerging commercial spaceflight industry. It was determined that the most effective policy architecture for ensuring public and private compliance with Planetary Protection places NASA in control of all domestic Planetary Protection matters, and in this role NASA is charged with overseeing, supporting, and regulating the private spaceflight industry. The underlying analysis and architecture tradeoffs that led to this recommendation are presented and discussed.
Download or read book Engineering a Robotic Exoskeleton for Space Suit Simulation written by Forrest Edward Meyen and published by . This book was released on 2013 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
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.
Download or read book Engineering Design Study of a Space Suit with an Integrated Environmental Control System written by Douglas C. Howard and published by . This book was released on 1968 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Equipotential Space suit Design Concept and Its Application to a Space suit Elbow Joint written by Donald E. Barthlome and published by . This book was released on 1969 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Space Suit Simulator for Partial Gravity Extravehicular Activity Experimentation and Training written by Andrea Lynn Gilkey and published by . This book was released on 2012 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Kinematic Analysis and Joint Hysteresis Modeling for a Lower body Exoskeleton style Space Suit Simulator written by Anthony J. Nejman and published by . This book was released on 2011 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: A mechanical exoskeleton has the capacity to replicate the properties of a pressurized space suit with regards to motion resistance. Using such an exoskeleton for ground based mission training and research provides a lower-cost, less operationally-complex alternative to using a space suit. To that end, NASA is supporting the development of such a device, termed a Space Suit Simulator (S3). The S3 must be designed to allow the wearer the same range of motion allowed in a space suit, and the joints must be actuated to produce the experienced resistive torques. The challenge moving forward is to develop a lower limb (ankle, knee, hip) exoskeleton and then a whole-body exoskeleton that includes multiple interconnected joints with some joints having multiple degree-of-freedom, such as the hip and shoulder. A kinematic design of the lower-body exoskeleton was developed by using Denavit-Hartenberg notation and transformation matrices to derive the Jacobian matrix, which was in turn used to develop a method of testing for singular configurations along a given path of motion. The S3 was tested for singularities while operating through a standard walking gait cycle, and no singularities were uncovered. Translational manipulability of the S3 end effector was analyzed at near-singular configurations along the gait cycle to determine directions of motion which may result in increased joint torques or loss of freedom of motion. A graphical representation of the leg and S3 end effector workspace verified that the S3 allows the human leg to move within the operational envelope anticipated during space suit use. The four degree-of-freedom exoskeleton design eliminates constrictive singularities by aligning human and exoskeleton joint axes. A computational algorithm, based on the Preisach hysteresis model, was used to mimic space suit joint hysteresis behavior in knee flexion and hip abduction/adduction, and it was demonstrated that linear actuators may be used to produce the required joint torque resistance. The kinematic design and computational hysteresis algorithms will support the further development of a physical space suit simulator.
Download or read book Quantifying Astronaut Tasks written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-04 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary aim of this research effort was to advance the current understanding of astronauts' capabilities and limitations in space-suited EVA by developing models of the constitutive and compatibility relations of a space suit, based on experimental data gained from human test subjects as well as a 12 degree-of-freedom human-sized robot, and utilizing these fundamental relations to estimate a human factors performance metric for space suited EVA work. The three specific objectives are to: 1) Compile a detailed database of torques required to bend the joints of a space suit, using realistic, multi- joint human motions. 2) Develop a mathematical model of the constitutive relations between space suit joint torques and joint angular positions, based on experimental data and compare other investigators' physics-based models to experimental data. 3) Estimate the work envelope of a space suited astronaut, using the constitutive and compatibility relations of the space suit. The body of work that makes up this report includes experimentation, empirical and physics-based modeling, and model applications. A detailed space suit joint torque-angle database was compiled with a novel experimental approach that used space-suited human test subjects to generate realistic, multi-joint motions and an instrumented robot to measure the torques required to accomplish these motions in a space suit. Based on the experimental data, a mathematical model is developed to predict joint torque from the joint angle history. Two physics-based models of pressurized fabric cylinder bending are compared to experimental data, yielding design insights. The mathematical model is applied to EVA operations in an inverse kinematic analysis coupled to the space suit model to calculate the volume in which space-suited astronauts can work with their hands, demonstrating that operational human factors metrics can be predicted from fundamental space suit information.Newman, DavaJohnson Space CenterHUMAN FAC
Download or read book Design of a Lower Extremity Exoskeleton to Increase Knee ROM During Valgus Bracing for Osteoarthritic Gait written by Jennifer M. Cao and published by . This book was released on 2017 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knee osteoarthritis (KOA) is the primary cause of chronic immobility in populations over the age of 65. It is a joint degenerative disease in which the articular cartilage in the knee joint wears down over time, leading to symptoms of pain, instability, joint stiffness, and misalignment of the lower extremities. Without intervention, these symptoms gradually worsen over time, decreasing the overall knee range of motion (ROM) and ability to walk. Current clinical interventions include offloading braces, which mechanically realign the lower extremities to alleviate the pain experienced in the medial compartment of the knee joint. Though these braces have proven effective in pain management, studies have shown a significant decrease in knee ROM while using the brace. Concurrently, development of active exoskeletons for rehabilitative gait has increased within recent years in efforts to provide patients with a more effective intervention for dealing with KOA. Though some developed exoskeletons are promising in their efficacy of fostering gait therapy, these devices are heavy, tethered, difficult to control, unavailable to patients, or costly due to the number of complicated components used to manufacture the device. However, the idea that an active component can improve gait therapy for patients motivates this study. This study proposes the design of an adjustable lower extremity exoskeleton which features a single linear actuator adapted onto a commercially available offloading brace. This design hopes to provide patients with pain alleviation from the brace, while also actively driving the knee through flexion and extension. The design and execution of this exoskeleton was accomplished by 3D computer simulation, 3D CAD modeling, and rapid prototyping techniques. The exoskeleton features 3D printed, ABS plastic struts and supports to achieve successful adaptation of the linear actuator to the brace and an electromechanical system with a rechargeable operating capacity of 7 hours. Design validation was completed by running preliminary gait trials of neutral gait (without brace or exoskeleton), offloading brace, and exoskeleton to observe changes between the different gait scenarios. Results from this testing on a single subject show that there was an observed, significant decrease in average knee ROM in the offloading brace trials from the neutral trials and an observed, significant increase in average knee ROM in the exoskeleton trials when compared to the brace trials as hypothesized. Further evaluation must be completed on the clinical efficacy of this device with a larger, and clinically relevant sample size to assess knee ROM, pain while using the device, and overall comfort level. Further development of this design could focus on material assessment, cost analysis, and risk mitigation through failure mode analysis.
Download or read book Mechanical Counter pressure Space Suit Design Using Active Materials written by Bradley Thomas Holschuh and published by . This book was released on 2014 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanical counter-pressure (MCP) space suits have the potential to greatly improve the mobility of astronauts as they conduct planetary exploration activities; however, the underlying technologies required to provide uniform compression in an MCP garment at sucient pressures (29.6 kPa) for space exploration have not yet been demonstrated, and donning and dong of such a suit remains a signicant challenge. This research effort focuses on the novel use of active material technologies to produce a garment with controllable compression capabilities to address these problems. We the describe the modeling, development, and testing of low spring index (C = 3) nickel titanium (NiTi) shape memory alloy (SMA) coil actuators designed for use in wearable compression garments. Several actuators were manufactured, annealed, and tested to assess their de-twinning and activation characteristics. We then describe the derivation and development of a complete two-spring model to predict the performance of hybrid compression textiles combining passive elastic fabrics and integrated SMA coil actuators based on 11 design parameters. Design studies (including two specifically tailored for MCP applications) are presented using the derived model to demonstrate the range of possible garment performance outcomes based on strategically chosen SMA and material parameters. Finally, we present a novel methodology for producing modular 3D-printed SMA actuator cartridges designed for use in compression garments, and test 5 active tourniquet prototypes (made using these cartridges and commercially available fabrics) to assess the eect of SMA actuation on the tourniquet compression characteristics. Our results demonstrate that hybrid active tourniquet prototypes are highly effective, with counter-pressures increasing by an average of 81.9% when activated (taking an average of only 23.7 seconds to achieve steady state). Maximum average counter-pressures reached 34.3 kPa, achieving 115.9% of the target MCP counter-pressure. We observed signicant spatial variability in the active counter-pressure profiles, stemming from high friction, asymmetric fabric stretching, and near-field pressure spikes/voids caused by the SMA cartridge. Modifications to reduce tourniquet friction were effective at mitigating a proportion of this variability. System performance and repeatability were found to depend heavily on the passive fabric characteristics, with performance losses attributable to irrecoverable fabric strain, degradation in fabric elastic modulus, and non-linear modulus behavior. The results of this research open the door to new opportunities to advance the field of MCP spacesuit design, as well as opportunities to improve compression garments used in healthcare therapies, competitive athletics, and battlefield medicine.
Download or read book Evaluation of the Mark III Spacesuit written by Conor Ryan Cullinane and published by . This book was released on 2018 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spacesuit Assemblies (SSAs) provide life support for human operators performing extravehicular activities (EVAs). The overall goal of this research was to investigate three research questions to address gaps in the field of spacesuit assembly (SSA) evaluations: [1] What are the mobility and agility limitations causing operators to experience performance decrements when wearing a SSA?; [2] What is causing operators to experience increased joint torques?; and [3] How does the distributed weight of an SSA, transferred to the operator, affect performance? This research leveraged both experimental and computational modeling capabilities to evaluate SSAs with a human-centered focus, in ways previously unachievable. The space suit evaluated for this research was NASA's Mark III (MkIII) Planetary Technology Demonstrator SSA, built to test the next generation in planetary exploration capabilities, improving upon Apollo era technology. The hip brief assembly (HBA) is built with three nested bearings, each with a single rotational degree of freedom that together provide the range of motion, walking efficiency, and kneeling capabilities. An initial investigation, combining a pilot study and supporting modeling, revealed limitations in the current human-SSA system that may impair the operator's mobility/stability and agility. Limitations identified and investigated in this thesis include SSA degrees of freedom (DOFs), the SSA range of motion (ROM) envelope, the bearing resistances, the SSA component's inertial effects, the SSA mass load transfer dynamics, and suit fit. The SSA architecture was modeled as part of the thesis, creating a tool that was useful in the investigation of the human-suit system. The model relied on SSA component geometries and inherent mass/inertia and bearing resistance characteristics to output joint dynamics, rather than requiring those dynamics as an input (which would require extensive experimental setups). The model was used to isolate components that contribute to the measured operator performance degradations and to quantify the extent of their contributions. These investigations lead to suggestions for design requirements and evaluation techniques that can guide future SSA development and evaluations.
Download or read book On the Deformation of Human Skin for Mechanical Counter Pressure Space Suit Development written by Edward William Obropta (Jr.) and published by . This book was released on 2015 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exploration of planetary bodies requires space suits that do not inhibit astronaut mobility. Gas pressurized suits are typically bulky and stiff to operate or require unnatural human motion. Development of mechanical counter pressure (MCP) space suits can change the current space suit design paradigm. The primary goal of this thesis is to develop methodology to quantify strain and deformation of human skin to inform how to make a MCP space suit, or second skin, that maximizes mobility and minimizes human energy expenditure. Specific emphasis was placed on joint mobility, therefore, the Lines of Non-Extension (LoNE) was investigated in detail throughout the deformation of the human elbow joint. This goal was driven by three research objectives: develop a system to measure human skin deformation and strain, develop a rigorous method to compute LoNE, and examine the variation of skin strain between multiple subjects. The contributions of this thesis are the development of a multi-camera system to measure skin deformation at 1 mm2, a streamline approach for calculating LoNE, strain data at the elbow joint and a methodology moving forward to measure more sections of the human body. The results from the six subjects showed that skin deformation can be similar in magnitude between subjects of varying anthropometrics, but the principal strain directions and LoNE maps can vary. The elbow data was flattened to 2D and normalized by anthropometrics to allow comparisons between subjects. This skin deformation data informs material selection, material placement, and suit patterning. This data is relevant to any compression garment or device that interacts with human skin.
Download or read book Designing Exoskeletons written by Luis Adrian Zuñiga-Aviles and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Designing Exoskeletons focuses on developing exoskeletons, following the lifecycle of an exoskeleton from design to manufacture. It demonstrates how modern technologies can be used at every stage of the process, such as design methodologies, CAD/CAE/CAM software, rapid prototyping, test benches, materials, heat and surface treatments, and manufacturing processes. Several case studies are presented to provide detailed considerations on developing specific topics. Exoskeletons are designed to provide work-power, rehabilitation, and assistive training to sports, and military applications. Beginning with a review of the history of exoskeletons from ancient to modern times, the book builds on this by mapping out recent innovations and state-of-the-art technologies that utilise advanced exoskeletons design. Presenting a comprehensive guide to computer design tools used by bioengineers, the book demonstrates the capabilities of modern software at all stages of the process, looking at computer-aided design, manufacturing, and engineering. It also details the materials used to create exoskeletons, notably steels, engineering polymers, composites, and emerging materials. Manufacturing processes, both conventional and unconventional are discussed- for example, casting, powder metallurgy, additive manufacturing, and heat and surface treatments. This book is essential reading for those in the field of exoskeletons, such as designers, workers in research and development, engineering and design students, and those interested in robotics applied to medical devices"--
Download or read book Modeling Space Suit Mobility written by P. B. Schmidt and published by . This book was released on 2001 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling and Tradespace Exploration of a Space Suit Hip Bearing Assembly Using Multi degree of freedom Range of Motion Analysis written by Patrick Calvin McKeen and published by . This book was released on 2019 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space suits are crucial to human spaceflight, but can restrict motion, require additional energy, and increase injury risk. Previous planetary suits were largely based on flexible components, which generate additional forces on the occupant as they resist volumetric changes from flexing components. The NASA Mark III suit addresses this problem using a Hip Brief Assembly (HBA), composed of rigid, constant-volume sections connected by bearings. However, due to the rigid components and fixed degrees of freedom (DoFs), the HBA and other hard-component joint assemblies (HCJAs) have stricter bounds on motion. For example, previous analysis shows that the hip multi-DoF range of motion (ROM) for an HBA occupant is not well-aligned with the nominal hip ROM during gait (gait NHROM). In this thesis, a set of methods for describing HCJA geometry and the effect on occupant ROM is presented. A generalized model builds on Denavit-Hartenberg parameterization to describe HCJA structure, rotation, and surface shape. Also included is a computational approach, compatible with standard 3D model files, to estimate the multi-DoF ROM for joints of an HCJA occupant, and compare and score the suit-restricted ROMs against nominal, unencumbered ROMs. These models are utilized to analyze HBA geometry and improve alignment between in-suit occupant ROM and gait NHROM. A set of design constraints based on feasible geometries and parameter bounds were devised and used to limit a tradespace analysis of alternate geometries in the HBA model. The geometries were evaluated and given an ROM score based on occupant access to gait NHROM. Over 1.3 billion alternate geometries were tested, and 10,912 met or bested the nominal geometry. The top-scoring geometry showed a more than sixfold improvement on access to gait NHROM, as well as a more natural neutral leg position, a significant increase in adduction range, and improved kneeling ability. The tradespace data set is also used to analyze trends in HBA geometry, suggesting two-bearing HBAs would have very poor hip ROM and the most dominant factors behind a high ROM score is the extent of the cant in the HBA Proximal and Distal sections.
Download or read book Design of a Passive Dual Joint Stance Assistance Knee Exoskeleton written by Minerva Vasudevan Pillai and published by . This book was released on 2014 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lower Extremity Exoskeleton technology has been geared towards benefiting medical and augmentation fields. Functional modularity in exoskeleton design allows practitioners to prescribe exoskeletons which can be geared towards the user's needs and abilities. While most modular knee exoskeleton technology either live in the realm of medicine or augmentation, a stance assistive knee exoskeleton can benefit both able bodied individuals as well as individuals with decreased quadriceps function or knee weakness. Fully passive systems are lower cost but have limited functionality. Powered systems have diverse functionality but are expensive and large. Microcontroller controlled resistive knees are more functionally diverse than fully passive system, but only provide system resistance to motion and can be expensive. Passive microcontroller controlled systems can lead to a low cost and functionally versatile system. By embedding some of the required functionality into the mechanical hardware of the system, the burden on the microcontrollers and need for sensors is reduced. To determine the required functionality the characteristic behavior of the knee during level walking and stair descent were studied. Characteristics for a stance assistive knee joint exoskeleton are derived using biomechanics data. These characteristics are 1) The joint provides resistance to flexion during stance 2) The joint does not impede extension during stance 3) The joint can enter free mode under load at any knee angle 4) The joint has very low impedance / is free while extending and flexing during swing A dual jointed architecture with a clutch connected across one joint and a torque generator connected across the other is developed to mechanically achieve requirements 1 and 4. By requiring the clutch or torque generator to provide resistance in one direction but no impedance in the other, characteristic 2 is achieved. By controlling the locking and unlocking of the clutch, characteristic 3 is achieved. The torque generator and clutch requirements can be fulfilled by several passive mechanical components. Several passive mechanical components were analyzed. It was determined that using a wrap spring clutch as the clutch and using a gas spring as the torque generator provides the required characteristics. This combination requires only a small actuator to lock and unlock the clutch. This combination also allows the restoration of energy during extension after it is stored during the resistance phases. This hardware combination results in a stance assistance knee exoskeleton which is relatively small, light and can further help reduce the metabolic cost associated with wearing an exoskeleton. A simplified controller was implemented to gauge system performance. Additional applications for the hardware architecture are proposed. These applications include use of the knee exoskeleton with a modular hip. The hardware is not limited to use as a knee exoskeleton. It can be used to reduce the erector spinae muscles forces in the back, if it is installed at the user's hip. Experiments are proposed to evaluate the effect of the device on the biological joint torque and user's metabolic cost.
