SBIR Phase II: Advanced Controlled-Impedance Transfemoral Knee/Ankle Prosthesis

This Small Business Innovation Research (SBIR) Phase II project aims to develop a transfemoral prosthesis which will allow wearers to walk and run more smoothly, with greater stability and less effort. Typically, transfemoral amputees have difficulty achieving a natural gait, thus causing discomfort and greater energy expenditure. It is expected that the development of this advanced prosthesis will greatly enhance the function and comfort of amputees and bring new technology to the prosthetic industry. In Phase I research, a unique engineering model of the knee and the ankle was developed, implementing the pneumatic compliance (spring) and electrically-controlled hydraulic damping. In Phase II, complete prototypes of the microprocessor-controlled knee/ankle prosthesis will be developed, with the following features: (a) compliant (elastic, rather than stiff) knee flexion during stance phase, which will return energy to the wearer and improve comfort, (b) co-ordination of knee and ankle impedance to match desired walking cadence, and minimal energy expenditure by tuning the spring rate to the natural frequency; and (c) myoelectric control of knee impedance. In addition, high-performance features will be integrated into the prosthetic device, including adaptive swing phase knee impedance, and automatic control of stance phase impedance. The commercial application of this project will be in the area of prosthetic devices for use by people with knee and foot (transfemoral) amputation. The proposed product will allow the amputees to wear their prosthesis for a longer time period, with less effort and more safety, and to walk on more rugged and uneven terrain. Estimates of revenues resulting from this project show gross sales starting at $750,000 per year, growing rapidly after 5 years to over $8,000,000.