Exploiting Bistability for High-Performance Dielectric Elastomer Resonators

Soft actuators with muscle-like motions have drawn increasing interests in areas such as bioinspired robotics and human–robot communications. Dielectric elastomers resonators (DERs), in particular, demonstrate outstanding output performance comparable to natural muscles by adopting a resonant actuation technique. However, their narrow resonant bandwidth results in poor adaptability and output consistency, thus greatly restrict their potential for real-world applications. To bridge this gap, this article presents a nonlinear mechanism coupled DER that exploits the inherent bistability and a unique subharmonic resonance to broaden the resonant bandwidth and to improve the output performance and energy efficiency. The proposed bistable DER demonstrates a broad resonant bandwidth that expands the resonant bandwidth of the DERs by over an order of magnitude. The inherent bistability also improves the power output by over two-fold and the energy efficiency by over four times in light viscous payload conditions. An intriguing nonlinear dynamic phenomenon, namely an isola, is uncovered both numerically and experimentally in this article, and is exploited to improve the energy efficiency and outputs of the DER at low applied electric field amplitudes. The outcomes of this article can offer guidelines for developing broadband and high-performing soft actuators.

I. Introduction

Resonant actuation is an intriguing technique commonly adopted by animals to achieve highly agile locomotion and to minimize the cost-of-transportation [1]. For instance,ects drive their muscle–thorax system at its resonance to optimize the exerted lift force [2]. Soft actuators are an emerging type of actuation technology that exhibit muscle-like motions; they have been successfully applied to areas such as bioinspired robotics [3], [4], human–robot communication [5], [6], and medical robotics [7], [8]. Among these soft actuation technologies, dielectric elastomer actuators (DEAs) can achieve an outstanding output power density and energy efficiency by utilizing the resonant actuation, which make the DEAs advantageous in realizing many highly dynamic robotic applications, such as insect-like micro-aerial vehicles (MAVs) [9], [10] or rapid running soft robots [11], [12].