Dual curvature control using pneumatic actuators

Pneu-Nets, or pneumatic networks have widely been used as extremely light soft actuators capable of gripping and performing a variety of locomotion such as forward and twisting movements. However, when dealing with sophisticated movements involving Pneu-Nets, previous researchers have used separate compartments to form a large system of Pneu-Nets to activate each channel in order to achieve a complex shape or function. Here, we present a novel design strategy of Pneu-Nets to achieve complex forms (dual curvature) from a single channel with a single compartment. Using the idea of strain hardening of hyperelastic elastomers, when controlled precisely to activate different regions of the same compartment, depending on the pressure of air which is present in the channels, two different forms or curvatures can be obtained from a single input to sequentially bend, stretch, and twist. Using Abaqus simulations, along with tensile tests on several combinations of commercial elastomers, Pneu-Nets with dual curvatures are designed and experimentally demonstrated to introduce a new paradigm in the field of soft actuators.