Design of a Testing Fixture for the Characterization and Modeling of a Powered Prosthetic Ankle Using a Lorentz Force Actuator

Abstract

Developments in prosthetic ankles have been improving amputee gaits, gradually approaching a more normal, non-amputee gait as designs develop. Currently, powered ankle prosthetics, or bionic ankles, hold the potential to mold the amputee gait much closer to its biological counterpart. This requires accurate control of the prosthesis and thus requires an accurate understanding of the plant model characterizing the bionic ankle. It is typically rather difficult to analytically develop such a model, so this project explores an experimental approach through the use of nonlinear stochastic system identification techniques to characterize the prosthetic. Results from initial experiments which use the method for characterizing known linear models revealed unaccounted for sources of error and nonlinearity which future work will attempt to remedy to continue developing such a characterization fixture.