Development of an active powered prosthesis system using position-based impedance control

In this paper, we discuss the implementation of an active powered knee prosthesis using position-based impedance control. We propose a new mechanical structure for knee prosthetics such that maintenance is more convenient and the noise in the load cell measurement, caused by a motor, is greatly reduced. We developed the embedded system based on a 32-bit digital signal controller and made a standalone operation without tethering possible by attaching the developed embedded system directly to the prosthesis. We divided the walking cycle into 5 stages and controlled the prosthesis such that it had different mechanical impedance depending on the stage. For efficient control of the impedance, we first derived the relationship between the knee angle and the torque applied to the knee, and then proposed a position-based impedance controller for the knee prosthesis. We evaluated the walking performance of the knee prosthesis through experiments, such as walking on a level surface or on an incline. We also analyzed the features of the proposed knee prosthesis by comparing the walking data of the proposed prosthesis with normal walking data. © ICROS 2017.