A Lightweight Powered Knee Prosthesis Replicating Early-Stance Knee Flexion During Level Walking

Chen, Wei; Ma, Yongxin; Ren, Lei; Liang, Wei; Wang, Xu; Zhang, Yao; Wei, Guowu; Ren, Luquan

Abstract

Powered knee prostheses promise to improve the mo- bility of transfemoral amputees by imitating the biomechanics of the missing knee joint. Unfortunately, the heavy weight and short battery life severely limit the application of powered prostheses. Here, we present a lightweight powered knee prosthesis, which employs a series elastic actuator (SEA) integrating a high torque density external rotor motor, a ball screw and a slider-crank mech- anism. A genetic algorithm (GA) is used to optimize the slider- crank mechanism’s key parameters and improve the prosthesis’s compactness. Combined with the hardware, a hybrid controller is proposed, which comprises impedance control in the stance phase with position control during the pre-swing and swing phases. The controller was applied to the powered prosthesis, and its capability to provide level walking functionality was evaluated on four above- knee amputees. The data obtained from these experimental trials indicated that the prosthesis could replicate the key biomechanical functions of a biological knee in the sagittal plane while the weight was lighter than most powered knee prostheses. In addition, the vertical ground reaction force (GRF) was quantitatively analyzed to validate that the powered knee prosthesis could improve wearing comfort with early-stance knee flexion.

• Journal Article Type: Article
• Acceptance Date: Jun 5, 2024
• Online Publication Date: Jun 19, 2024
• Publication Date: 2024-11
• Deposit Date: Oct 3, 2024
• Journal: IEEE Robotics and Automation Letters
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Issue: 11
• Pages: 1-8
• DOI: https://doi.org/10.1109/lra.2024.3416799