Dynamic Magnetorheological Damper for Orthotic Tremor Suppression

This paper explores the design methodology and effectiveness of small-scale magnetorheological dampers (MRDs) in applications that require rapidly variable damping. Previously applications of MRDs have been chiefly limited to vehicle shock absorbers and seismic vibration attenuators. There has been recent biomedical interest in active-damping technology, particularly in the field of rehabilitation robotics. The topic at hand is the feasibility of developing MRDs that would be functionally and dimensionally adequate for actuation of an upper limb tremor suppression orthosis. A nonlinear Bingham plastic model is used to determine the MRD’s functional characteristics, and experimental data is presented to validate the mathematical model. In addition, the dynamic response of the damper to step input signals and its bandwidth were estimated to explore its potential use in applications that require variable force at relatively high frequencies. A finite element analysis of the magnetic field within the damper was performed, resulting in an optimized design.