Slit Tubes for Semisoft Pneumatic Actuators

Abstract

This article describes a new principle for designing soft or 'semisoft' pneumatic actuators: SLiT (for SLit-in-Tube) actuators. Inflating an elastomeric balloon, when enclosed by an external shell (a material with higher Young's modulus) containing slits of different directions and lengths, produces a variety of motions, including bending, twisting, contraction, and elongation. The requisite pressure for actuation depends on the length of the slits, and this dependence allows sequential actuation by controlling the applied pressure. Different actuators can also be controlled using external "sliders" that act as reprogrammable "on-off" switches. A pneumatic arm and a walker constructed from SLiT actuators demonstrate their ease of fabrication and the range of motions they can achieve.

A new class of semisoft pneumatic actuators, which can achieve a range of complex motions, is presented. The arrangement of slits into an external, thin-walled and inextensible shell (which constrains the inflation of a silicone tube) controls the motions of soft pneumatic actuators. This design enables the fabrication of a pneumatically actuated arm and a walker.

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