A Novel Robotic Variable Stiffness Mechanism Based on Helically Wound Structured Electrostatic Layer Jamming

TL;DR

This paper presents a new helical electrostatic layer jamming mechanism for robotic fingers that offers exponentially tunable stiffness with reduced size, validated through experiments and a functional prototype.

Contribution

It introduces the HWS-ELJ mechanism with a helical design for improved stiffness control and demonstrates its practical application in a robotic finger prototype.

Findings

HWS-ELJ provides exponential stiffness adjustment with winding angle.

Experimental results confirm the theoretical stiffness modulation trends.

A robotic finger prototype successfully demonstrates voltage-driven stiffness control.

Abstract

This paper introduces a novel variable stiffness mechanism termed Helically Wound Structured Electrostatic Layer Jamming (HWS-ELJ) and systematically investigates its potential applications in variable stiffness robotic finger design. The proposed method utilizes electrostatic attraction to enhance interlayer friction, thereby suppressing relative sliding and enabling tunable stiffness. Compared with conventional planar ELJ, the helical configuration of HWS-ELJ provides exponentially increasing stiffness adjustment with winding angle, achieving significantly greater stiffness enhancement for the same electrode contact area while reducing the required footprint under equivalent stiffness conditions. Considering the practical advantage of voltage-based control, a series of experimental tests under different initial force conditions were conducted to evaluate the stiffness modulation characteristics of HWS-ELJ. The results demonstrated its rational design and efficacy, with outcomes following the deduced theoretical trends. Furthermore, a robotic finger prototype integrating HWS-ELJ was developed, demonstrating voltage-driven stiffness modulation and confirming the feasibility of the proposed robotic variable stiffness mechanism.