High-performance magneto-rheological clutches for direct-drive actuation: Design and development

Abstract

This paper presents an improved design, complete analysis, and prototype development of high torque-to-mass ratio Magneto-Rheological (MR) clutches. The proposed MR clutches are intended as the main actuation mechanism of a robotic manipulator with five degrees of freedom. Multiple steps to increase the toque-to-mass ratio of the clutch are evaluated and implemented in one design. First, we focus on the Hall sensors’ configuration. Our proposed MR clutches feature embedded Hall sensors for the indirect torque measurement. A new arrangement of the sensors with no effect on the magnetic reluctance of the clutch is presented. Second, we improve the magnetization of the MR clutch. We utilize a new hybrid design that features a combination of an electromagnetic coil and a permanent magnet for improved torque-to-mass ratio. Third, the gap size reduction in the hybrid MR clutch is introduced and the effect of such reduction on maximum torque and the dynamic range of MR clutch is investigated. Finally, the design for a pair of MR clutches with a shared magnetic core for antagonistic actuation of the robot joint is presented and experimentally validated. The details of each approach are discussed and the results of the finite element analysis are used to highlight the required engineering steps and to demonstrate the improvements achieved. Using the proposed design, several prototypes of the MR clutch with various torque capacities ranging from 15 to 200 N·m are developed, assembled, and tested. The experimental results demonstrate the performance of the proposed design and validate the accuracy of the analysis used for the development.

Design and Modeling of a Smart Torque-Adjustable Rotary Electroadhesive Clutch for Application in Human-Robot Interaction

“…As seen, the rendered torque of the haptic device perfectly tracks the desired environmental torque in both forward and backward motions. The clutch is able to track the desired torque in backward (positive) direction as long as the velocity of the operator's hand is lower than the rotation velocity of the clutch rotor [18]. The same performance can be seen in Fig.…”

A low-power magnetorheological fluid clutch utilizing electropermanent magnet arrays

“…Other relevant MRF-based clutch designs that utilize active electromagnets to transmit torque require being on for the entirety of maximum (or minimum) torque transmission for 1 hour. One sample design using this modality requires about about 3.5 W Pisetskiy and Kermani (2021), which translates to 3,500 mWh of power consumption for maximum torque transmission. The MEC consumes several orders of magnitude less energy than comparable devices for the same function (in this calculation, only 0.036% of the electromagnet-based design).…”

“…Other researchers developed a small-scale MRF clutch and compared it to that of a traditional DC motor for potential use in haptic feedback systems Najmaei et al (2014). Another publication developed and characterized a five degree-of-freedom robotic arm with MRF clutches in each joint; electromagnets in conjunction with a permanent magnet were used to control a specific range of magnetic field to variably control the joint stiffness at each joint Pisetskiy and Kermani (2021). A recent article developed an upper leg prosthesis, combining a MRF clutch with an MRF brake to provide improved energy efficiency compared to a motor-reducer for walking de Andrade et al (2021).…”

“…This is not an EPM, since it does not represent latching on or off-states, but instead requires active input to raise or lower the effective output of the permanent magnet. This strategy is utilized in the robotic arm described in the previous paragraph Pisetskiy and Kermani (2021).…”

Experimental Evaluation of Modified Groundhook Car Suspension with Fast Magnetorheological Damper

“…Magnetorheological (MR) technology is widely used [4] in controllable mechanical devices (clutches [5], brakes [6], and seals [7]), and it appears to be a good option for the semi-active control of dampers [8]. The MR damper uses MR fluid, which is a suspension of ferromagnetic particles in the carrier fluid [9].…”