Dynamic tests of MR (Magnetorheologic) damper and analysis of response characteristics in semi-active knee prosthesis

摘要

MR (Magnetorheologic) cylinders are often preferred to dampen the torques generated, in today's mechanical and electromechanical designs. In this study, a design containing MR cylinder was revisited, an MR current drive circuit was designed and a set of preliminary tests were performed to evaluate the dynamic behavior of the cylinder. After ensemble phase of the MR cylinder, prosthesis frame, and the current drive circuit, force-velocity (push-pull) tests were carried out at various operating speeds. Comparatively examined results showed that the reaction force increases with the increase of the current value and gave the hysteresis curves under which linear regions can be determined. Prosthetic walking was also examined in order to assess the dynamic response characteristics of the cylinders. MR and Pneumatic based prostheses were observed and quantified in terms of the responses and adaptation ability to walking phase changes. These tests and applied control strategies showed that the response time of the MR cylinder under proper current excitation is much better than pneumatic cylinder behavior.