Application of Magneto-Rheological Fluid based clutches for improved performance in haptic interfaces

The two main objectives in designing a haptic interface are stability and transparency. The dynamics of the actuators employed in a haptic interface have a significant effect on these goals. In this article, the potential benefits of Magneto-Rheological 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. This contributes significantly 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 degrees-of-freedom (DOF) haptic interfaces are used in a virtual wall experiment. These devices take advantage of an MRF-based clutch and a brushless DC motor at their core, respectively. The results of both devices are compared and show the superiority of the MRF-based clutch. In addition, design and analysis of a small-scale MRF-based clutch, suitable for a multi-DOF haptic interface, is given and its torque capacity, inertia, and mass are compared with those of conventional servo systems. Conclusions drawn from this investigation indicate that MRF clutch actuation approaches can indeed be developed to design haptic interfaces with improved stability and transparency.