High customization costs and reduction of natural mobility put current rehabilitative knee braces at a disadvantage. A
resolution to this problem is to integrate a Magnetorheological (MR) fluid-based joint into the system. A MR joint will
allow patients to apply and control a resistive torque to knee flexion and extension. The resistance torque can also be
continuously adjusted as a function of extension angle and patient strength (or as a function of time), which is currently
impossible with state of the art rehabilitative knee braces. A novel MR fluid-based controllable knee brace is designed
and prototyped in this research. The device exhibits large resistive torque in the on-state and low resistance in the offstate.
The controllable variable stiffness, compactness, and portability of the system make it a proper alternative to
current rehabilitative knee braces.
The disadvantage of current knee braces ranges from high cost for customization to a loss in physical mobility and limited rehabilitative value. One approach to solving this problem is to use a Magnetorheological (MR) device to make the knee brace have a controllable resistance. Our design solution is to replace the manufacturer's joint with an rotary MR fluid based shear damper. The device is designed based on a maximum yield stress, a corresponding magnetic field, a torque and the MR fluid viscosity. The analytical and experimental results show the advantages and the feasibility of using the proposed MR based controllable knee braces.