Analysis and application of a rolled dielectric elastomer actuator with two degrees of freedom

A rolled dielectric elastomer (DE) actuator with two degrees of freedom, which can bend and elongate, was implemented by membrane pre-stretching, interdigital shape electrode patterning, and wrapping on a compression spring. Then modeling of the actuator was conducted by constructing and solving differential equations, which include constitutive, geometrical, equilibrium equations and boundary conditions. Experiments show the actuator can bend up to 75.3 degrees and elongate with a displacement of 8.4 mm at the voltage of 5.0 kV, which agree well with analytical results. The principal stress and stretch ratio distribution of each layer of elastomer were given, on which the effects of electrostatic pressure and interlayer pressure were also discussed. Two crawling robots with a single and a double-actuator were proposed, and their locomotion performance was investigated. Locomotion experiments show two robots can move forward with both bending and elongation strategies, and the maximum velocity reaches 20 mm s(-1). This research is favorable to the application of soft DE in biomimetic robots.