Multifunctional Electroelastomer Roll Actuators and Their Application for Biomimetic Walking Robots

Abstract

Dielectric elastomer artificial muscles (electroelastomers) have been shown to exhibit excellent performance in a variety of actuator configurations. By rolling highly prestrained electroelastomer films onto a central compression spring, we have demonstrated multifunctional electroelastomer rolls (MERs) that combine load bearing, actuation, and sensing functions. The rolls are compact, have a potentially high electroelastomer-to-structure weight ratio, and can be configured to actuate in several ways including axial extension and bending, and as multiple degree-of-freedom (DOF) actuators that combine both extension and bending. 1-DOF, 2-DOF, and 3-DOF MERs have all been demonstrated through suitable electrode patterning on a single monolithic substrate. The bending MER actuators can act as leg and knee joints to produce biomimetic walking that is adaptable to many environments. Results of animation and the fabrications of a robot model of a synthetic bug or animal based on the MERs are presented. A new concept for an antagonist actuator for more precise control is introduced.

Advances in Dielectric Elastomers for Actuators and Artificial Muscles

“…Reliability is an issue as the spring and end caps may generate areas of localized high stress that may result in premature failure. Spring rolls capable of both bending and elongation have been reported by Pei et al [250][251][252] Bending is achieved by patterning the electrodes; for two and three degree-offreedom actuators two and three electrically isolated electrode pairs are required respectively. By actuating one electrode pair, only a portion of the actuator will elongate, causing the actuator to bend.…”

Large-scale failure modes of dielectric elastomer actuators

“…This positive feedback leads to an unstable compression of the elastomer material with catastrophic failure. In these studies, the one-dimensional models with linear stress/strain relationships predicted pull-in threshold values of about half of the extensions reported in the literature, see for example Pei et al (2003) and Plante et al (2005). Hence, linear models are inadequate to deal with the significant nonlinear behavior of DEAs (large deformation and nonlinear elasticity).…”

“…doi:10. 1016/j.ijsolstr.2006.03.026 A number of different DEA designs have been implemented in the past decade, see for example: Kornbluh et al (1995), Pelrine et al (1998), Wingert et al (2002b), Pei et al (2003), Vogan et al (2004) and Plante et al (2005). Some of these proof-of-concept actuators have shown extensions up to three times their initial lengths, acceptable efficiencies and specific energy densities.…”

A mathematical model for cylindrical, fiber reinforced electro-pneumatic actuators

“…Due to the incompressibility of the elastomer the thickness reduction is accompanied by an areal expansion. Most of dielectric elastomer research has concentrated on experimental performance and design (Kornbluh et al, 2000;Pei et al, 2004;Pei et al, 2003;Pelrine et al, 1998;Pelrine et al, 2000a;Pelrine et al, 2000b;Pelrine et al, 2002;Sommer-Larsen and Kofod, 2002;Wingert et al, 2002). Pelrine et al were the first researchers to exploit the electrostatic effect to develop compliant actuators.…”

“…Begley conducted experimental and theoretical analyses of dielectric elastomers fabricated using ultra thin metal electrodes, focusing on electrode crack spacing (Begley et al, 2005). Mathematical models have been developed for the uniaxial extension of cylindrical tubes (Carpi and de Rossi, 2004), and bending and extension of cylindrical roll actuators (Pei et al, 2003). Both models assume a linear elastic constitutive response whilst acknowledging that a more accurate model could be obtained by accounting for material nonlinearities.…”