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Exploring the Role of Damping in a Passive Prosthetic Knee Through Modeling, Design, and Testing

2019
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Release : 2019
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Book Synopsis Exploring the Role of Damping in a Passive Prosthetic Knee Through Modeling, Design, and Testing by : Nina T. Petelina

Download or read book Exploring the Role of Damping in a Passive Prosthetic Knee Through Modeling, Design, and Testing written by Nina T. Petelina. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: With about 440,000 people with an above-knee amputation in India alone, there is a great need for high performance prosthetic knee. Due to socio-economic stigma associated with amputation, one of the main requirements for a lower limb prosthesis is achieving able-bodied kinematics. However, the prostheses available in developing countries, such as India, primarily focus the design on stability and low cost. This study presents a shear-based rotary viscous damper design for late stance and swing flexion for a passive single-axis knee prosthesis. The optimal normalized damping coefficient range of 0.012 - 0.014 ... was determined by optimizing a set of passive components to replicate a knee moment for an able-bodied subject and transtibial amputee wearing a fully characterized prosthetic foot. Dampers with a stacked fin architecture, where a highly viscous fluid is sheared between neighboring disks, were built with a range of damping coefficients from 0.37 to 1.80 Nm/(rad/s). The performance of dampers was evaluated through field and clinical testing with unilateral transfemoral amputees. The results of the studies showed that not only damping is required to prevent hyper flexion, but the optimal damping range allows achieve a peak knee flexion close to able-bodied. In future design, the validated damping selection framework will be used to expand the prosthetic knee design to other gait activities such as walking at different speeds, on slopes or uneven terrains.

Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking

2019
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Release : 2019
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Book Synopsis Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking by : Venkata Narayana Murthy Arelekatti

Download or read book Frameworks for the Design of Passive Prosthetic Knee Components Using User-centered Methods and Biomechanics of Level-ground Walking written by Venkata Narayana Murthy Arelekatti. This book was released on 2019. Available in PDF, EPUB and Kindle. Book excerpt: Passive knee prostheses in developing countries use low-cost components driven primarily by the need to prevent falls, resulting in undesirable gait deviations during walking. There is a severe lack of reliable data on the specific needs of low-income amputees, which poses a significant challenge towards developing globally appropriate prosthetic technology. This thesis presents the analysis of user-centered needs and relevant lower leg dynamics as frameworks for the design of passive prosthetic knee components that can enable transfemoral (above-knee) amputees to ambulate with minimal gait deviations leading to higher user satisfaction. The goal of developing these frameworks is ultimately to design a low cost, fully passive prosthetic knee device for persons with transfemoral amputations living in the developing world. To identify user needs, structured oral interviews of 19 transfemoral amputees in India were conducted regarding 22 different Activities of Daily Living (ADLs). A scale of relative importance for different needs was compiled, which can help designers, doctors, and administrators provide better clinical solutions to amputees. Cross-legged sitting was identified as the most critical user need with the potential for highest improvement in the quality of life of amputees. Two identical rotator prototypes were designed and validated for cross-legged sitting on 9 amputees in India. To compute and replicate the target knee moment profile for a prosthetic knee device, the dynamics of level-ground walking were analyzed using a conceptual link-segment model of the prosthetic leg with the knee joint modeled as a combination of passive linear springs and dampers. The effects of changes in inertial properties (mass, radius of gyration, and center of mass location) of the prosthetic leg on the lower leg kinetics were also quantified in the model. The knee moment required for achieving normative joint kinematics at the hip, knee and ankle by the optimal engagement of spring and dampers was replicated computationally with a maximum R2=0.90 in an idealized clutching scheme. Multiple prototypes of modular knee mechanisms were built to replicate the model, including (i) an automatic locking module for stability during early stance, (ii) a linear spring module for facilitating knee flexion-extension during early stance, and (iii) a rotary damping module for control during terminal stance and swing. Qualitative feedback from two unilateral transfemoral amputees in India showed the automatic locking module provided the predicted performance for timely stance to swing transition. Fluid-based viscous damping was found to provide more optimal control compared to friction-based damping. A comprehensive biomechanical framework was developed that predicted the range of optimal damping coefficients for transfemoral amputees. The framework used the results from the link-segment model and empirical data of transfemoral gait characteristics such as slower walking speeds and asymmetries in the stance-swing duration. An experimental prosthetic knee with five different damping conditions was built and tested on three subjects with unilateral transfemoral amputation in a motion capture lab. Increased damping led to reduced peak knee flexion during terminal stance and swing, as predicted by the framework. The framework predicted the optimal damping value for achieving normative peak knee flexion to within one standard deviation of the able-bodied value during the swing phase.

Analysis and Optimization of Passive Knee Prosthetic Design Parameters Over Varying Cadences

2017
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Release : 2017
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Book Synopsis Analysis and Optimization of Passive Knee Prosthetic Design Parameters Over Varying Cadences by : Krithika Swaminathan

Download or read book Analysis and Optimization of Passive Knee Prosthetic Design Parameters Over Varying Cadences written by Krithika Swaminathan. This book was released on 2017. Available in PDF, EPUB and Kindle. Book excerpt: The need for effective prostheses is prevalent worldwide, and is especially dire in developing countries and low-resource settings. The MIT GEAR Lab is addressing this gap through the ATKnee, a low-cost, passive prosthetic knee that employs the use of spring and damper components to replicate the knee torque of the able-bodied human knee. In this study, we build upon prior work to optimize the components used in the ATKnee by accounting for results from field-testing. We first develop an inverse dynamics model to confirm understanding of previous work. We then use a genetic optimization algorithm to optimize parameters across different walking speeds and various spring-damper configurations. The best fit, as measured by the highest R2 value, is obtained when a viscous damper is active during the first dissipative phase (b*11 ), a friction damper is active during the second dissipative phase (b*/20 ), and an additional friction damper is active throughout both phases (b*/0). We make the suggestion that b*/0 = 0.084, b*/11 = 0.008, b*/0 = 0.183, gives the most optimal passive system knee torque with the engagement and disengagement timings teng = 51.3%, tdis1 = 64.2% for the first damper, and teng2 = 86.1%, tdis2 = 95.2% for the second damper. We find that the parameters are robust to subject body mass, but show a positive correlation with walking speed. We conclude that while we are able to suggest an optimized parameter set that includes higher order dampers, it will be important to investigate the effects of cadence, as well as to study the joint torques at the hip, which is further from the foot.

Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation

2013
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Release : 2013
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Book Synopsis Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation by : Yashraj Shyam Narang

Download or read book Identification of Design Requirements for a High-performance, Low-cost, Passive Prosthetic Knee Through User Analysis and Dynamic Simulation written by Yashraj Shyam Narang. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: In January 2012, a partnership was initiated between the Massachusetts Institute of Technology and Bhagwan Mahaveer Viklang Sahayata Samiti (BMVSS, a.k.a., Jaipur Foot) to design a high-performance, low-cost, passive prosthetic knee for transfemoral amputees in India. The knee was primarily intended to improve the walking gait of amputees relative to existing low-cost devices. This thesis aimed to identify detailed design requirements for the prosthetic knee through user analysis and dynamic simulation. User analysis identified the needs and constraints of numerous stakeholders in the prosthesis development process. Members of the Indian biomechanics, prosthetics, and rehabilitation communities were interviewed to identify general requirements for the design, manufacturing, evaluation, and fitting of a prosthetic knee, and a structured survey of Indian amputees was conducted to quantify the demographics, functional capabilities, and functional needs of future end users. Dynamic simulation identified methods to enable transfemoral amputees to walk with reduced energy expenditure and normative gait kinematics. 2-dimensional inverse dynamics simulations were used to calculate the effects of inertial alterations of a prosthetic leg on the energy expenditure required to walk with normative kinematics. In addition, simulations were performed to compute the effects of inertial alterations on the knee moment required to walk with normative kinematics. Mechanical power analysis, sensitivity analysis, and optimization were used to formulate a passive mechanical model that could accurately reproduce the specified knee moment. The effects of walking cadence on critical results were also examined. Through the identification of user-centered and biomechanical requirements, the thesis provides a blueprint for the mechanism design comprising the next phase of the project.

Biomechanics of Prosthetic Knee Systems

2013 Artificial knee
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Release : 2013
Genre : Artificial knee
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Book Synopsis Biomechanics of Prosthetic Knee Systems by : Hande Argunsah Bayram

Download or read book Biomechanics of Prosthetic Knee Systems written by Hande Argunsah Bayram. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: One significant drawback of the commercial passive and microprocessored prosthetic devices, the inability of delivering positive energy when needed, is due to the absence of the knee flexion during stance phase. Moreover, consequences such as circumduction and disturbed gait pattern take place due to the improper energy flow at the knee and the absence of the positive energy delivery during the swing phase. Current generation powered design has solved these problems by delivering the needed energy with heavy battery demanding motors, which increase the mass of the device significantly. Hence, the gait quality of transfemoral amputees has not improved significantly in the last 50 years due to the inefficient energy flow distribution causing the patient to hike his/her pelvis, which leads to back pain in the long run. In this context, state-of-art prosthetics technology is trending toward creating energy regenerative devices, which are able to harvest/ return energy during ambulation by a spring mechanism, since a spring not only permits significant power demand reduction but also provides high power-to-weight ratio. This study will examine the sagittal plane knee moment versus knee flexion angle properties robotically, clinically and theoretically to explore the functional stiffness of a healthy knee as well as a prosthetic knee during the energy return and harvest phases of gait. With this intention, a prosthetic knee test method will be developed for investigating the torque-angle properties of the knee by iteratively modifying the hip trajectory until achieving the closest to healthy knee biomechanics by a 3-Degree of Freedom (DOF) Simulator. This research reveals that constant spring stiffness is suboptimal to varying gait requirements for different types of activity, due to the variability of the power requirements of the knee caused by the passive, viscous and elastic characteristics and the activation dependent properties of the muscles. Exploring this variation is crucial for the design of transfemoral prosthetic devices that aim to mimic normal gait. This research will contribute to a better understanding of determination of the prosthetic knee design strategy; hence, by using modern computational tools, a prosthetic knee device could be simulated even before initiating the hardware design process.

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