Design of a Pneumatically Actuated Transfemoral Prosthesis

This paper describes the design of an above-knee prosthesis with actively powered knee and ankle joints, both of which are actuated via pneumatic actuators. The prosthesis serves as a laboratory test-bed to validate the design and develop of control interfaces for future self-contained versions (i.e., with onboard hot-gas power and computing), and therefore includes a tether for both pneumatic power and control. The prototype prosthesis provides the full range of motion for both the knee and ankle joints while providing 100% of the knee torque required for fast cadence walking and stair climbing and 76% and 100%, respectively, of the ankle torque required for fast cadence walking and for stair climbing, based on the torques required by a healthy 75 kg subject. The device includes sensors to measure knee and ankle torque and position, in addition to a load cell that measures the interaction force and (sagittal and frontal planes) moments between the user and device.Copyright © 2006 by ASME