Small MR-Brake With Serpentine Flux Path and T-Rotor for Haptics

In haptics applications, fast, stable and crisp force responses are desired. Magnetorheological (MR) brakes are used as actuators in haptics since they provide high torque-to-volume ratios. However, they still tend to be rather large and use high current inputs. We developed a new MR-brake with a T-rotor and serpentine flux path. The new device has 45 mm diameter and 65 mm length. It produces 6.5 Nm torque with 1A current input. It has more than double the torque-to-volume ratio of a commercial MR-brake and a previous T-rotor brake in literature. As such, it can open up many new application areas including portable systems. A prototype was built and tested to assess its effectiveness as a 1 degree-of-freedom (DOF) haptic device in virtual wall collision. The new MR-brake provided a crisp collision and release with the virtual wall.Copyright © 2013 by ASME