Robotic Tentacles with Three‐Dimensional Mobility Based on Flexible Elastomers

Buckling of Elastomeric Beams Enables Actuation of Soft Machines

“…[4,5] The first generation of these systems-originally sketched by Suzumori, [6][7][8] and then realized and elaborated by us, [5,[9][10][11][12][13] and by others [4] -use pneumatic actuators, comprising networks of micro-channels; in our systems, differential expansion of these pneumatic networks (PneuNets) by pressurization using air produces motions (especially bending, curling, and variants on them) that are already established as useful in grippers, and interesting for their potential in walkers, tentacles, and a number of other soft, actuated systems. [14] 4 Although the design of the first of these systems has been relatively simple, the motion they produce on actuation can be surprisingly sophisticated: for example, a representative structure-the "finger" or "tentacle" of a gripper-curls non-uniformly, starting from its tip and proceeding to its stem, although the pressure applied in the PneuNet is approximately uniform throughout the system of inflatable channels.…”

“…It is based on a cooperative, reversible, buckling motion in structures consisting of a slab of an elastic polymer (or other elastic material) containing arrays of interacting beams and void spaces, when subjected to uniform compression. Previous studies of soft machines (grippers and tentacles) [5,9,10] have focused on actuations that produce motions based primarily on bending: e.g., grasping and walking. The buckling motions produced in the systems described here result in torsional motions, with angular rotations of ~30°, localized at specific points in the structures.…”

“…This type of adaptability is characteristic of many soft pneumatic-based systems. [5,9,10] Conclusion. This paper describes a new strategy for actuating soft machines.…”

“…[14] 4 Although the design of the first of these systems has been relatively simple, the motion they produce on actuation can be surprisingly sophisticated: for example, a representative structure-the "finger" or "tentacle" of a gripper-curls non-uniformly, starting from its tip and proceeding to its stem, although the pressure applied in the PneuNet is approximately uniform throughout the system of inflatable channels. [10,11] This motion reflects a non-linear property of soft materials and structures, referred to as a "snapthrough instability". [15][16][17][18][19] Although nonlinear properties of materials are often considered a disadvantage, this type of non-linearity, illustrated by snap-through, and other complex mechanical characteristics of soft systems, are proving to be useful, and to offer new capabilities to effectors, machines, and robots, because they enable a range of motions of sufficient complexity that-although they might be possible to replicate in a hard robotic system [20] -it would be complicated and expensive to do so.…”

“…This type of adaptability is characteristic of many soft pneumatic-based systems. [5,9,10] This gripper can hold and lift objects of complex shapes (for example, a toy elephant; Figure S5a, supporting video: gripper_toy.mp4), and a 50 g standard weight ( Figure S5b, supporting video: gripper_weight.mp4).Using buckling actuators for locomotion. Soft buckling actuators have potential applications in devices that translate/locomote: they are light, and (in principle) adaptive to their environment.…”