A Dual-Bearing Magnetorheological Grease Clutch with Intention-Based Demagnetization for Wearable Haptic Feedback
For wearable haptic feedback systems, this work addresses the leakage and sticky sensation problems of MR clutches, but the improvements are incremental over existing MR fluid devices.
This paper presents a dual-bearing magnetorheological grease clutch for wearable haptic feedback that avoids leakage issues and achieves a maximum locking torque of 43.42 N·m and torque-to-mass ratio of 96.5 N·m/kg. An intention-based demagnetization control strategy accelerates clutch release and improves perceived transparency and smoothness.
This paper presents the design, modeling, and control of a dual-bearing magnetorheological grease (MRG) clutch for wearable haptic feedback. Compared with conventional MR fluid devices, the proposed clutch avoids leakage-related reliability degradation while achieving high torque density in a compact structure. To provide physical insight into the torque-generation mechanism, a physics-inspired interpretive model is introduced to capture the dominant relationship among excitation current, magnetic-field evolution in the bearing gaps, and clutch locking torque. To mitigate the undesirable ``sticky'' sensation caused by passive bidirectional braking, an intention-based control strategy with active demagnetization is further developed to enable smoother release during human--robot interaction. Experimental characterization shows that the proposed clutch achieves a maximum locking torque of 43.42\,N$\cdot$m at 1.3\,A and a torque-to-mass ratio of 96.5\,N$\cdot$m/kg. Bench tests, replay validation, teleoperation experiments, and user studies indicate that the proposed approach accelerates clutch release and improves perceived release transparency and contact-to-release smoothness, while maintaining effective multi-level kinesthetic rendering.