Estimation of Knee Angles Based on Thigh Motion: A Functional Approach and Implications for High-Level Controlling of Active Prosthetic Knees

Abstract

Human locomotion is the result of complex neuromusculoskeletal cooperation between different joints and limbs of the lower extremities. This collaboration (also called synergy [1]) results in an energyefficient gait. Unfortunately, for an above-knee amputee, this cooperation is lost since current prosthetic devices do not emulate the missing functionality in a manner similar to their biological counterparts. Transfemoral amputees can select between passive (Mauch knee [2]), semi-active (Ottobock's C-leg [3] and Ossur's rheo knee [4]), and active prosthetic devices (Ossur's power knee [5]). What distinguishes the active ones from the other two is the injection of positive power for activities such as ascending stairs and standing up from a chair.