Gripping characteristics of an electromagnetically activated magnetorheological fluid-based gripper

Young T Choi,Christine M Hartzell,Norman M Wereley,Thomas Leps

doi:10.1063/1.5006094

Abstract

The design and test of a magnetorheological fluid (MRF)-based universal gripper (MR gripper) are presented in this study. The MR gripper was developed to have a simple design, but with the ability to produce reliable gripping and handling of a wide range of simple objects. The MR gripper design consists of a bladder mounted atop an electromagnet, where the bladder is filled with an MRF, which was formulated to have long-term stable sedimentation stability, that was synthesized using a high viscosity linear polysiloxane (HVLP) carrier fluid with a carbonyl iron particle (CIP) volume fraction of 35%. Two bladders were fabricated: a magnetizable bladder using a magnetorheological elastomer (MRE), and a passive (non-magnetizable) silicone rubber bladder. The holding force and applied (initial compression) force of the MR gripper for a bladder fill volume of 75% were experimentally measured, for both magnetizable and passive bladders, using a servohydraulic material testing machine for a range of objects. The gripping performance of the MR gripper using an MRE bladder was compared to that of the MR gripper using a passive bladder.

Highlights

Robotic grippers have been developed to emulate the dexterity of the human hand because the human hand can perform power grips, and precision grips for delicate and precise tasks in various work scenarios
The magnetorheological fluid (MRF) synthesized for this study used a high viscosity linear polysiloxane (HVLP) carrier fluid, in which were dispersed carbonyl iron particles (35 vol%)
The holding force of the passive bladder case was smoothly reduced after a peak value and became zero after much larger displacement than the magnetorheological elastomer (MRE) bladder case

Summary

Introduction

Robotic grippers have been developed to emulate the dexterity of the human hand because the human hand can perform power grips, and precision grips for delicate and precise tasks in various work scenarios. To decrease system complexity and to minimize the need for sensors and actuators for such simple tasks as picking and holding that require no delicate manipulation of the gripped object, universal grippers based on granular jamming have been recently developed.[2,3,4] Granular-jamming universal grippers have an elastic bladder that is filled with a granular material and passively conforms to an object’s shape and size. Universal granular-jamming grippers are simple and low cost but can grip a wide range of objects without relying on extensive sensors, actuators and feedback control. The universal granular-jamming gripper requires a vacuum pump and an air source to evacuate or inflate the bladder to enable gipping and release of objects, which limits how compact the gripping system due to the added volume and weight of the air handling components.

Methods

Results

Conclusion