In this paper, an exoskeleton for human knee is proposed. This design is based on the magnetorheological (MR) fluid theory and its application on vibration damper. The damper is analyzed and developed to suit the human motion. The motor torque is optimized that the knee torque is smallest as possible. After formulating the equations related to motor torque, external forces on human leg and damper force, the design is undertaken followed by optimization using ANSYS APDL software. The objective function in this software is concentrated on maximal damping force of damper (supporting 30% force when human foot lands on the ground).
This paper deal with a semi-active type bush design and magnetic analysis associated with the magnetorheological elastomer. It is focused on the magnetic field intensity analysis with 3 coil structure. The bush design consists of 3 coil structure of the bush in order to apply the magnetic field. As a result of first investigation, it is found that MRE thickness and electric current are most important parameters to design an effective bush. From the magnetic analysis, it is identified that the magnetic permeability of the MRE is lower than MR fluid. In addition, the bush model is formulated to have the uniformity of the magnetic flux and intensity field distribution.
Magnetorhological fluids (MR) have been applied to numerous devices or systems which require forward or feedback control to achieve desired performances. One of applications is the rehabilitation device. MR dampers applied to artificial joints are implemented with two phases; stance phase: motion to support the feet on the ground, and swing phase : motion to step out. In case of stance phase, the damping force should be increased by applying the magnetic field to support the body. On the other hand, in case of swing phase, the damping force should be removed by not applying the magnetic field so that the prosthesis can be easily rotated by the motor. In this study, a special mechanism of MR damper is proposed to make a prosthetic leg which can derive on/off mode using permanent magnet only. The design mechanism is undertaken and damping force is analyzed to validate the effectiveness of the proposed damper system for the patient’s motion without control device.