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.

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.

This book presents the selected peer-reviewed proceedings of the International Conference on Innovative Engineering Design (ICOIED 2020). The contents provide a multidisciplinary approach for the development of innovative product design and their benefits for the society. The book presents latest advances in various fields like design process, service development, micro/nano technology, sensors and MEMS, and sustainability in engineering design. This book can be useful for students, researchers, and professionals interested in innovative product/process design and development.

This book presents cutting-edge research and developments in the field of biomedical engineering, with a special emphasis on achievements by Asian research groups. It covers machine learning and computational modeling methods applied to biomedical and clinical research, advanced methods for biosignal processing and bioimaging, MEMS applications, and advances in biosensors. Further topics include biomechanics, prosthetics, orthotics and tissue engineering. Other related (bio-) engineering applications, such as in ecosystem development, water quality assessment, and material research, are also covered. Gathering the proceedings of the 6th Kuala Lumpur International Conference on Biomedical Engineering, held online on July 28-29, 2021 from Kuala Lumpur, Malaysia, the book is intended to provide researchers and professionals with extensive and timely information on the state-of-the-art research and applications in biomedical engineering, and to promote interdisciplinary and international collaborations.

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.

An estimated 230,000 above-knee amputees are in need of prosthetic devices in India with a majority of them facing severe socio-economic constraints in their daily lives. However, only a few passive prosthetic knee devices in the market have been designed to enable normative gait and to meet the unique daily life needs of above-knee amputees in the developing world. This thesis builds upon a past study at MIT, which established optimal mechanical component coefficients in prosthetic knee function required for achieving able-bodied kinematics. A mechanism for the design of a fully passive, low-cost prosthetic knee device, which aims to facilitate able-bodied kinematics at a low metabolic cost is presented. The mechanism is implemented using an automatic early stance lock for stability, a linear spring for early stance flexionextension and a differential friction damping system for late stance and swing control. For preliminary validation of the knee mechanism two field trials were carried out on five above-knee amputees in India, which showed satisfactory performance of the early stance lock and enabled smooth stance to swing transition by timely initiation of late stance flexion.

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.