The Construction of a Soft Gripper Based on Magnetorheological Elastomer with Permanent Magnet

TL;DR

This paper addresses the design of a soft gripper using magnetorheological elastomer (MRE) and a permanent magnet to enable self-closure without continuous power. The authors model the MRE–PM interaction as a magnetic spring, deriving the rolling torque from magnetic coenergy with $W_{co}(\theta)$ and $T_{co}(\theta)$ and validating with finite-element simulations. They fabricate a three-finger MRE gripper, integrate a linear electromagnet, and demonstrate gripping performance on several objects with a high success rate (≈97%) and lifting capacity up to ~$97\ \text{g}$. The approach is simple, energy-efficient, gravity-insensitive, and scalable, offering a practical route to soft grippers that can handle delicate items.

Abstract

Recently, magnetorheological elastomers have become an interesting smart material with many new designs for robotics. A variety of applications have been built with magnetorheological elastomers, such as vibration absorbers, actuators, or grippers, showing that this material is promising for soft robotics. In this work, the novel concept of a gripper is proposed, exploring the features of a magnetorheological elastomer and permanent magnet. The gripper uses the energy of a permanent magnet to provide a self-closing gripping mechanism. The usage of flexible material enables one to hold delicate objects of various shapes. This paper presents the rolling effect of magnetorheological elastomer and permanent magnet, the design process, and the features of the soft gripper. The effectiveness of the soft gripper was validated in a series of experiments that involved lifting different objects.

Figures (13)

• Figure 1: The working principle of MRE stripe attached to a permanent magnet. (a) pulling force causing rolling. (b) steady state.
• Figure 2: The magnetic field in MRE stripe attached to the permanent magnet with example contact angles equal to 60°.
• Figure 3: The magnetic coenergy versus angle for MRE stripe rolling on permanent magnet (a) and the force characteristics (b) calculated from virtual work principle.
• Figure 4: The cylindrical permanent magnet with MRE stripe rolled in.
• Figure 5: The idea of the gripper moves to the open and closed state. Elements: MRE (grey), permanent magnet (red), and mounting frame (blue).