Buckling Elements for Elastomer Deformation

Buckling instabilities can be the cause for dramatic breakdown in a variety of systems. However, this paper seeks to exploit the addition of buckling elements within soft robotic systems, to create a passive binary switch from a stiffened system to an unstiffened system via a quick, predictable response. This binary switch essentially operates as a high pass filter for pressure, restraining motion at low pressures and allowing full control at high pressures. To test, the proposed elements were attached to fluidic elastomer actuators in three configurations, the first with no element, the second with an element that extended across all internal pneumatic chambers and a third that offset the element, allowing the first two pneumatic chambers to actuate prior to buckling. The actuators were then inflated and their pressure and curvature responses were recorded with respect to volume. Buckled elements are shown to suppress effective curvature at low pressures, prior to buckling. Post buckling, the rate of effective curvature increases. The snap angle of buckling for each of the constrained systems is shown to be 19.6° for the fully constrained pneu-net and 28.6° for the pneu-net with offset buckling element (averaged across five trials). This paper proposes the use of such buckling elements in responsive gripping technologies and as a method for morphological change.