| dc.description.abstract | Replication of healthy knee behavior after amputation requires prosthetic knees to provide active and resistive stance behaviors, as well as ballistic and non-ballistic swing behaviors. Current state-of-the-art prosthetic knees are deficient in providing one or more of these behaviors. This work describes a novel approach to the design and control of a powered knee prosthesis that provides a sufficiently low impedance to enable a fully ballistic swing-phase, while also providing sufficiently high torque to offer stance-phase knee-extension during activities such as step-over stair ascent. Replication of active/resistive stance and ballistic/non-ballistic swing is achieved by employing feedback control, as is conventional in powered knee prostheses, but also by widening the range of behaviors achieved via feedback control by employing mechanical reconfiguration of the transmission between the stance and swing phases of gait. As such, the device can operate in one of two behavioral regimes: 1) a low-impedance, low-torque, high-speed regime with characteristics appropriate for either ballistic swing or for powered swing when appropriate; and 2) a relatively higher-impedance, high-torque, and lower-speed regime appropriate for either resistive stance or active stance depending on the gait situation. Experiments with a single study participant with a transfemoral amputation are presented that compare the functionality of the resulting design and control approach with that of a conventional passive microprocessor-controlled knee prosthesis. | |
