A Lightweight Magnetorheological Actuator Using Hybrid Magnetization

This article presents the design and validation of a lightweight magnetorheological (MR) clutch, called hybrid magnetorheological (HMR) clutch. The clutch utilizes a hybrid magnetization using an electromagnetic coil and a permanent magnet. The electromagnetic coil can adjust the magnetic field generated by the permanent magnet to a desired value and fully control the transmitted torque. To achieve the maximum torque-to-mass ratio, the design of the HMR clutch is formulated as a multiobjective optimization problem with three design objectives, namely the transmitted torque, the mass of the clutch, and the magnetic field strength within the clutch pack. A prototype of the HMR clutch is fabricated, and its dynamic performance is experimentally validated. Experimental results clearly demonstrate the advantages of the HMR clutch in applications requiring fast and precise motion and torque control.