Vibration analysis and testing of magnetorheological fluid damper for transtibial prosthetic limb

Abstract

The damping characteristics of a healthy limb change throughout the gait cycle. However, for transtibial amputees who are wearing mechanically passive damping prostheses, the lack of ability to change the damping values might expose them to injuries and health problems during the impact of heel strike. The use of magnetorheological fluid damper in prosthetic limb, which provides a wide dynamic range, seems to be able to prevent these conditions from taking place, due to its response to the magnetic field. In this work, the vibration characteristics of a transtibial prosthetic limb with a magnetorheological (MR) fluid damper have been numerically analyzed and experimentally investigated. A simplified single-degree-of-freedom model has been developed to represent the transtibial prosthetic limb with the damper. The model is then utilized to analyze the response of the prosthetic limb along with the damper when subjected to impact, with and without semi-active control, numerically. The MR fluid damper and attachments to transtibial prosthetic limb have also been tested with impulse excitation to obtain its response with and without semi-active control. Finally, the numerical and experimental results have been compared to show the increase in efficiency of the damping of vibrations experienced during the heel strike of the gait cycle while using the semi-actively controlled magnetorheological fluid damper in the transtibial prosthetic limb.