Modeling and simulation of a magnetorheological knee brake

Currently, many prosthetic devices are available on the market. However, most of these devices are inefficient because they are either difficult to operate, require too much power, or they are extremely costly. Magnetorheological (MR) fluid is a smart fluid; a prosthesis carried out with this fluid requires less power than other devices and is simpler to operate. The purpose of the study is to theoretically model a prosthetic knee and predict the braking torque. A knee similar to MR brake was designed. The proposed design of the MR fluid knee features a non-circular rotor, which results in a variable gap size for the MR fluid between the stator and the rotor. The torque generated by the MR fluid knee is highly dependent on the gap size, angle, and the applied current. Therefore, the gap size varies with the angle of the knee. When the current is applied and MR knee is subjected to a magnetic field, it produces yield stress due to the shear friction which results in the generation of variable braking torque. The braking torque generated is the function of angle and the applied current. A torque equation is derived from the theoretical data to yield the predicted results.