Jamming Metal Sheets Using Electropermanent Magnets for Stiffness Modulation
Leah T. Gaeta, Vi Vo, Sang-Yoep Lee, Srushti Raste, Megha Venkatesam, Jacob Rogatinsky, Deniz Albayrak, Tommaso Ranzani
AI summary
Problem
Existing soft robot stiffening techniques either lack portability due to bulky pneumatic systems or suffer from slow response times, hindering their widespread adoption in dynamic applications.
Approach
The researchers electronically activate electropermanent magnets to generate magnetic fields that instantly jam stacked flexible steel sheets, rapidly increasing structural rigidity and damping without continuous power draw.
Key results
- Up to 68% stiffness increase in 10-layer steel samples under magnetic jamming
- Dynamic energy absorption reaching 113 mJ during cantilever oscillation
- Optimal stiffening achieved with ≤10 layers, with magnetic field strength diminishing in thicker stacks
- Successful integration into wearable haptic feedback and a miniaturized Skee-Ball game
Why it matters
Provides a lightweight, electronically controllable stiffening solution for soft robotics and wearables, enabling faster, more adaptable robotic interactions without pneumatic infrastructure.
Abstract
Soft robots exhibit natural compliance which is desirable in many applications, but often require stiffness mod- ulation techniques when more rigidity is needed. However, many existing stiffening techniques lack portability or fast response times, hindering the ubiquitous adoption of soft robots. Here we introduce a new rapid stiffness modulation method based on magnetism that exhibits portability due to electronic control. This technique jams together thin layers of inherently magnetic metal sheets with a magnetic field generated by electropermanent magnets (EPMs), producing rapid stiffness changes. Quasi- static and dynamic mechanical characterizations for samples with varied layer numbers are presented, highlighting how the magnetic attraction generated by EPMs can be exploited to create a jamming effect. Stiffness increases of up to 68% and energy absorptions of up to 113 mJ were found during quasi-static and dynamic characterizations, respectively. Finally, we demonstrate how this jamming technique can be used in a haptic feedback application and to play a miniaturized version of the game of Skee-Ball®.