Abstract: This study aims to develop a magnetorheological (MR) damper for semi-active knee prostheses to restore the walking ability of transfemoral amputees. The core dimensions of the MR damper were determined via theoretical magnetic feld calculations, and the theoretical relationship between current and joint torque was derived through electromagnetic simulation. Then, a physical prototype of the semi-active prosthetic knee equipped with the MR damper was manufactured. Based on the data obtained from angle sensor, pressure sensor (loadcell), and inertial measurement unit (IMU) on the prosthesis, a matching control algorithm is developed. The joint torque of the MR damper can be adaptively adjusted according to the walking speed of the amputee, allowing the amputee to realize a natural gait. The efectiveness of the control program was verifed by the ADAMS and MATLAB co-simulation. The results of the test and simulation show that the MR damper can provide sufcient torque needed for normal human activities.

Key words: Semi-active knee prosthesis , · Magnetorheological damper , · Theoretical analysis , · ADAMS and MATLAB co-simulation