Optimal Design of a Magneto-Rheological Damper for Above-Knee Prosthetic Leg

It is well-known that above-knee prosthetic leg (AKPL) is one of the most important rehabilitation devices for lower limb amputees to regain mobility, independence, and improve their quality of life. Passive AKPLs are simple and economical, but cannot provide the individuals with ordinary human gait due to the lack of damping force/torque adjustability in real-time. Contrarily, although active AKPLs can control the knee joint motion for coordinated walking, their complicated structure and control scheme make them primarily focus on high-end market. Therefore, in this research, a magneto-rheological fluid-based damper (MRD) is proposed for semi-active AKPLs. By changing the applied magnetic field strength, the produced damping force can be adjusted corresponding to specific movements of AKPLs. Following an overview of AKPLs, rectangular and trapezoidal configurations of the MRD are studied. An optimization procedure using finite element analysis (FEA) is then conducted for the MRD design configurations, considering the mass, expected damping force and installability. From the obtained solutions, the optimal design for the proposed MRD is presented with detailed discussions.