SBIR Phase I: Quasi-Active Prosthetic Ankle System: Dynamic Angle and Stiffness Optimizations for Multiple Gait Activities

The broader impact/commercial potential of this project is that its successful completion will lead to greater access to improved, smart prosthetics devices. The proposed work will develop assistive technology for the lower limb amputee population. The majority of the 1.8 million Americans suffering from limb loss have a lower limb amputation. Living with a lower limb loss results in severe long term health challenges; hip and knee replacement surgeries, Osteoarthritis, Osteoporosis, reduced activity levels, increased weight gain, socket discomfort, and chronic lower back pain. The proposed system promises to improve health by supporting a more active lifestyle through increased walking comfort and efficiency. This has significant societal impact on the growing amputee population through increased community and family involvement. Because of the many possibilities to control the proposed research device, human mobility scientists will be able to study amputee walking compensations by tuning different parameters on the system. This new tool will likely lead to new concepts on how to further reduce the long term consequences of amputee walking. This research is targeted for functional level K2 and above amputees. Improving functionality without increasing the cost over similar systems means the market potential and societal impact will be substantial. This Small Business Innovation Research (SBIR) Phase I project is focused on the support of individuals that have lost a lower limb. Living with the loss of a lower limb has severe effects on an individual?s mobility, including; reduced walking speed, increased reliance on the healthy limb, increased walking asymmetry, difficulty navigating uneven surfaces, and reduced stability with increased risk of falling. Proper ankle angle adaptation to a sloped surface is important for amputees, otherwise severe compensations arise in their remaining joints. The research objective of the proposed work is to develop a prosthetic ankle that adapts its equilibrium position to a slope while dynamically optimizing its torsional stiffness. These features will ensure a natural loading response on the amputated limb while providing the most possible assistance from a passive system. A unique actuator design that can simultaneously change its length and stiffness properties will be incorporated into an ankle prosthesis. This prosthesis will be microprocessor controlled, and while not adding positive energy to a step, it will optimize angle and stiffness parameters at every point within the step. The result of such a device would be improved walking stability, comfort, and efficiency for a lower limb amputee.