Mechatronic Design and Implementation of a Low-Noise Powered Knee Prosthesis With High Backdrivability

Working noise is an important consideration that hinders the acceptance of powered prostheses by amputees. In this article, we present a powered knee prosthesis with low noise and high backdrivability. The powertrain of the proposed prosthesis consists of a motor and a four-stage synchronous belt to decrease working noise. At the same time, benefiting from the low impedance of the motor and low impedance design, the proposed prosthesis is endowed with the characteristics of low impedance, and thus, high backdrivability. A three-layer control method based on a finite state machine is implemented, and walking experiments have been carried out on a transfemoral amputee. The results show the characteristics of the proposed prosthesis in low impedance, low noise, and the ability to reproduce a natural gait. In particular, the working noise of the proposed prosthesis is less than 46 dBA most time, which is lower than common household appliances, and may have positive effects on the acceptance of daily uses.