Low inertia torque controllable device using magnetorheological fluid & umbrella-shaped rotor

Magnetorheological fluids (MRFs) are composite materials made of ferromagnetic particles, medium oils, and several types of additives. Their rheological properties change rapidly, stably, and repeatedly when magnetic fields are applied. In this study, we developed a new torque controllable device using the MRF. An umbrella-shaped rotor with multi-layered disc structure was utilized to reduce its inertia. MRF-140CG was used as a sample material for the MRF in this study and modeled with Bingham fluid model in off-state and on-state. Design procedures and validation experiments were conducted for a prototype. According to the design results, the torque/inertia ratio was around 400 00 Nm kgm(-2), which is the same as a coreless motor for haptic devices. According to the experimental results, the max/min torque ratio was around 75 at 0.5 rad s(-1).