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

Motion Control, Inc., Salt Lake City UT

Investigators

Abstract

This Small Business Innovation Research Phase I project seeks to develop a microprocessor controlled transfemoral knee/ankle prosthesis. This system will include: (1) adaptive swing phase impedance (resistance); (2) control of compliant flexion during stance phase; (3) myoelectric control of knee/foot impedances; and, (4) coordination of knee and foot motion. This transfemoral knee/ankle prosthesis would allow prosthesis users to walk and run more smoothly, stably, and with less effort. Two important developments are necessary for the realization of this objective. The first is the refinement of experimental knee and foot mechanisms, which have previously been developed and the second is the development of an adaptive control system, which will command these mechanisms to exhibit appropriate impedances. There are over 80,000 transfemoral prosthesis users in the United States and there is an estimated a market for 20,000 transfemoral prostheses each year. Considering all industrial nations, the worldwide market is several times that figure. U.S. government sponsored workshops have cited .the following as high priority goals for improved knee systems: stance phase stability, varying walking cadences, and energy conservation. Other manufacturers have shown the feasibility of using electronic control of hydraulic knee resistance, and the C-leg (by Otto Bock, of Germany) controls flexion impedance during stance phase. However all the available knees lack compliant stance and coordinated knee/ankle motion, which this project will develop.