Modeling the viscoelastic creep of the cylindrical dielectric elastomer actuator

Cylindrical dielectric elastomer actuator (CDEA) is known as an effective type of dielectric elastomer actuators. Owing to the advantageous properties of compact structure, CDEA has shown promising potential application in the development of the soft robotics. However, the inherent nonlinear viscoelasticity of dielectric elastomers causes the strain of actuators to change with time. This feature of CDEA is challenging to modeling and control of DE actuator and may limit their motion accuracy in practical applications. In this paper, to accurately describe the time-dependent nonlinear viscoelasticity properties of the actuator, by combining the advantages of the Kelvin-Voigt model and the Generalized Maxwell, a generalized combination model is proposed. The comparisons between the model prediction and experimental results demonstrate that the proposed model can accurately predict the response of the actuator under step voltage excitation, and the minimum prediction error can be achieved by 1.97%. This research results can provide theoretical guidance for the design of CDEA and is helpful to reduce the creep effect and improve the control efficiency of the CDEA.