Design and Dynamic Response Analysis of a Multipole Multidisc Magnetorheological Fluid Brake

Abstract

This article designs a multipole multidisc magnetorheological (MR) brake aimed at overcoming the problems of low torque-to-power ratio and low torque density of traditional MR brakes. This brake adopts a hybrid magnetization with an outer coil and an inner coil group. The structural description is presented first. The magnetic field strength within MR fluid gaps could be increased or decreased by the combination of the magnetic fields generated by the coils. Magnetic circuit modeling is proposed to evaluate the magnetic field strength within fluid gaps. Then, simulations are developed to study the performance of the proposed brake. A prototype of the brake is manufactured and its performance is verified by experiments. The experimental results demonstrate that the proposed brake can generate a maximum braking torque of 134.6 Nm at 1.0-A coil current, with a torque density of 18.69 kNm−2, and a torque-to-power ratio of 1.93 NmW−1. The multipole multidisc MR brake has a superior torque-to-power ratio, and a high torque density. Finally, the closed-loop feedback control of the braking torque is carried out. The proposed GA-optimized fuzzy proportional-integral–derivative (PID) controller has a higher torque tracking accuracy. The results confirm the feasibility of the proposed MR brake design and control system.