Design and Experimental Analysis of a Biomedical Prosthetic Knee With Magnetorheological Fluid

Current prosthetic legs rely on technology that is inefficient. Electric motors used today require high amounts of current to operate. Prostheses utilizing smart materials, including magnetorheological fluid (MRF), require less power to operate effectively. In this study, the MR fluid knee was designed for above the knee amputees. The design was in the family of MR fluid brake/clutch as it provides simple design and good MR fluid uniformity. However, this MR knee design is different from any existing MR brake, featuring a novel non-circular rotor. Three fourths of the rotor, considered circular, has the same radius, and the remaining quarter has a varying radius to provide a variable gap size between the rotor and stator. This feature allows the MR fluid to experience a stronger magnetic field as the knee rotates, resulting in a variable braking torque. At this stage of research, the first working prototype of the proposed MR fluid knee was built and tested to determine the braking torque profile. Corresponding theoretical models were also created. The calculated torque was used to predict the performance of the MRF knee. The experiments has been conducted to examine the MRF knee performance and to compare with the theoretical model. The knee was expected to use less power to operate and provided the necessary braking torque required by an average male human body. An improved design was planned for weight reduction and optimization to allow the commercialization of the MRF knee.