STTR Phase I: Integrated Powered Knee-Ankle Prosthetic System

This Small Business Technology Transfer (STTR) Phase I research project proposes the development of the design features, sensory system and the control algorithm of an integrated powered knee-ankle power regenerative prosthesis. Despite significant advances in lower limb prosthetics over the past decade, all presently commercially available lower limb prostheses incorporate passive ankle joints. That is, the joints of the prostheses can either store or dissipate energy, but cannot provide any net power over a gait cycle. The inability to deliver joint power significantly impairs the ability of these prostheses to restore many locomotive functions, including level walking, walking up stairs, walking up slopes, running, and jumping, all of which require significant net positive power at the knee joint, ankle joint, or both. The objective of this proposal is to investigate the use of integrated powered knee and ankle joints in transfemoral prostheses that use sensory information from the ground and the wearer. The hypothesis is that a prosthesis with actively powered knee and ankle joints will significantly enhance the mobility of transfemoral amputees while walking on level grounds, as well as stairs and slopes. The proposed work will result in new theoretical frameworks for both the control, sensory system, and design of such systems. Major intellectual contributions will include the design of power systems; development of the sensory system to obtain information from the ground and from the user; the development of a control framework for the interactive control of prostheses; and the development of adaptive and robust controllers for impedance modulation during locomotion. This project intends to create principles that provide significantly greater functional capabilities for above-knee amputees. Specifically, the proposed work will enable more natural, stable, and adaptable prostheses. These research elements in this proposal will also form a foundation for powered orthotic systems. Additional significant benefits of this work include fostering a broader awareness and increased sensitivity of young engineers and educational institutions to disability issues. Limb loss also affects a growing number of military personnel serving in recent conflicts, as well as a far larger number of veterans from previous wars.