Performance Study of Low Inertia Magnetorheological Actuators for Kinesthetic Haptic Devices

Abstract

A challenge to high quality virtual reality (VR)simulations is the development of high-fidelity haptic devices that can render a wide range of impedances at both low and high frequencies. To this end, a thorough analytical and experimental assessment of the performance of magnetorheological (MR) actuators is performed and compared to electric motor (EM) actuation. A 2 degrees-of-freedom dynamic model of a kinesthetic haptic device is used to conduct the analytical study comparing the rendering area, rendering bandwidth, gearing and scaling of both technologies. Simulation predictions are corroborated by experimental validation over a wide range of operating conditions. Results show that, for a same output force, MR actuators can render a bandwidth over 52.9% higher than electric motors due to their low inertia. Unlike electric motors, the performance of MR actuators for use in haptic devices are not limited by their output inertia but by their viscous damping, which must be carefully addressed at the design stage.

Design and characterization of a miniaturized low inertia and low viscous friction magnetorheological clutch using 3D metal printing for human-robot applications

“…All measured data are compared to an equivalent drum-type MR clutch with similar mass and volume used in previous work (Lebel et al, 2021) and made with conventional machining processes. The reference clutch reaches a maximum torque of 0.4 N.m at 7 A, with a 140-turn coil of 28 AWG wire and three output drums.…”

“…Their actuators must have a high torque density while having low mass and inertia. To ensure the back drivability of such robot—which is the ability to move it by its end effector—the actuator system must show low friction and inertia (Lebel et al, 2021). Magnetorheological (MR) actuators have been shown suitable for those applications, by decoupling the inertia and friction from the motor and transmission and thus reducing the reflected mass, friction and inertia of the end effector (Shafer and Kermani, 2011a; Veronneau et al, 2018).…”

“…The magnetic flux can be generated by a permanent magnet (Bucchi et al, 2014; Rizzo et al, 2015), but is often generated by a magnetic coil for fast response actuators (Fauteux et al, 2010). The shear interface can have various geometries (Nam and Ahn, 2009; Pisetskiy and Kermani, 2020; Singh et al, 2020; Wang et al, 2013) but the two main geometries are the disk type (Bucchi et al, 2017; Pisetskiy and Kermani, 2021; Shafer and Kermani, 2011b) and the drum type (Lebel et al, 2021; Qin et al, 2018; Rossa et al, 2014; Figure 3). Another type is called serpentine, and consists of one large drum where the magnetic flux crosses the same MR fluid gap several times, in a serpentine way (Blake and Gurocak, 2005; Senkal and Gurocak, 2009).…”

Toward a Digital Twin for Arthroscopic Knee Surgery: A Systematic Review

“…Closely related to actuation is the transmission of forces from actuator to the haptic device, where traditional methods for impedance devices are capstan and direct drives [123]. Recently, Lebel et al [132] compared the use of magnetorheological (MR) clutches to lower reflected inertia of haptic devices. They found the MR clutch system to have approximately 50 % more bandwidth, 190 % less reflected inertia, and 66 % more damping than a DC-motor system.…”