Asymmetric stable deformations in inflated dielectric elastomer actuators

Robotic systems that are soft or incorporate soft actuators are well suited for operation in unstructured environments and for safe interactions with fragile objects. The majority, however, are tethered or burdened with bulky payloads of pumps and compressors. In a recent article we presented a sealed, inflated actuator composed of fluidically connected membrane dielectric elastomer actuators capable of large, repeatable, and stable deformations. Each membrane could switch between two identical volumes, and maintain its shape when an applied voltage was removed. Here we extend our previous work by simulating and demonstrating asymmetric stable deformations. In an experimental two-membrane setup, the membranes experience large and significantly different area strains of >100% and >550% when transitioning between stable states. With the addition of more membranes, this asymmetry can increase the number of discrete stable membrane sizes, allowing more complex control when later implemented in a mechanism.

I. Introduction

Soft actuators and systems comprise an exciting development in the field of robotics, coveted for their ability to operate in unpredictable cluttered environments, exhibit robustness to high impacts and chemicals, and facilitate compliant and safe interaction with fragile or living specimens while allowing inexpensive, simple manufacturing methods. Traditionally, most soft systems produce motion by shifting fluid around in flexible chambers using large compressors or pumps through tethers or bulky payloads. Naturally, these limitations have prompted research into methods for untethered operation. Examples of such recent work include the use of on-board air compressors [1], [2], micro-pumps [3], monopropellant liquid fuels [4], [5], or explosive fuels [6].