Design and Preliminary Assessment of Lightweight Swing-Assist Knee Prosthesis

This paper presents the design and control of a lightweight swing assist (SA) knee prosthesis. The SA knee relies on passive stability to provide support during the stance phase of walking and incorporates a small motor and battery to actively assist the knee motion during the swing phase. A prototype SA knee was constructed and experimentally evaluated on a single transfemoral amputee. The experiments consisted of treadmill walking at three speeds, first on a dailyuse passive prosthesis and subsequently on the SA prosthesis prototype, while recording motion capture and ground reaction force data from which prosthesis knee kinematics and affectedside hip torque were computed. A comparison of the passive daily-use prosthesis and the SA prosthesis indicates that the SA prosthesis provides more consistent and repeatable knee motion and reduces pre-swing peak hip torque across all walking speeds.