An Experimental Characterization of Mechanical Layer Jamming Systems

TL;DR

This paper experimentally investigates mechanical layer jamming in soft robotics, analyzing how design parameters affect stiffness modulation and providing insights for optimized system design.

Contribution

It identifies key design parameters for mechanical layer jamming and quantifies their effects on stiffness modulation under bending and torsion loads.

Findings

Peak stiffness change of 5 times in bending

Peak stiffness change of 3.2 times in torsion

Measured separation force between jammed layers

Abstract

Organisms in nature, such as Cephalopods and Pachyderms, exploit stiffness modulation to achieve amazing dexterity in the control of their appendages. In this paper, we explore the phenomenon of layer jamming, which is a popular stiffness modulation mechanism that provides an equivalent capability for soft robots. More specifically, we focus on mechanical layer jamming, which we realise through two-layer multi material structure with tooth-like protrusions. We identify key design parameters for mechanical layer jamming systems, including the ability to modulate stiffness, and perform a variety of comprehensive tests placing the specimens under bending and torsional loads to understand the influence of our selected design parameters (mainly tooth geometry) on the performance of the jammed structures. We note the ability of these structures to produce a peak change in stiffness of 5 times in bending and 3.2 times in torsion. We also measure the force required to separate the two jammed layers, an often ignored parameter in the study of jamming-induced stiffness change. This study aims to shed light on the principled design of mechanical layer jammed systems and guide researchers in the selection of appropriate designs for their specific application domains.