Suitability of Small-Scale Magnetorheological Fluid-Based Clutches in Haptic Interfaces for Improved Performance

Haptic information provides important cues in teleoperated systems. It enables the user to feel the interaction with a remote or virtual environment during teleoperation. The two main objectives in designing a haptic interface are stability and transparency. An actuator with poor dynamics, high inertia, large size, and heavy weight can significantly undermine these goals. In this article, the potential benefits of magnetorheological fluid (MRF)-based actuators to the field of haptics are discussed. Devices developed with such fluids are known to possess superior mechanical characteristics over conventional servo systems. These characteristics significantly contribute to improved stability and transparency of haptic devices. In this study, this idea is evaluated from both theoretical and experimental points of view. First, the properties of such actuators which motivated this research are discussed. Next, two single degree-of-freedom (DOF) haptic interfaces, one with an MRF-based clutch and the other with a brushless DC motor, are compared in a virtual wall experiment in order to show the superiority of the MRF-based clutch. In addition, the design of a small-scale MRF-based clutch, suitable for a multi-DOF haptic interface, is discussed and its torque capacity, inertia, and mass are compared with conventional servo systems. Conclusions drawn from this investigation indicate that MRF-based actuation approaches can indeed be developed to design haptic interfaces with improved stability and transparency.