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Underactuated fluidic control of a continuous multistable membrane

Significance Mechanical elements which exhibit several equilibria states and snapping instabilities are increasingly popular in the design of microelectromechanical systems, mechanical logic systems, origami structures, and especially in soft robotics. All previous research examined the actuation dynamics of either a single bistable element or multistable structures, which are an assembly of discrete bistable elements. In this work, we present analysis and experimental demonstration of underactuated fluidic control of a continuous multistable structure, enabling us to arbitrarily pattern such continuous structures by a single pressure inlet. These continuous multistable structures inherently have infinite possible stable patterns, thus offering an essential increase in versatility. This work addresses the challenge of underactuated pattern generation in continuous multistable structures. The examined configuration is a slender membrane which can concurrently sustain two different equilibria states, separated by transition regions, and is actuated by a viscous fluid. We first demonstrate the formation and motion of a single transition region and then sequencing of several such moving transition regions to achieve arbitrary patterns by controlling the inlet pressure of the actuating fluid. Finally, we show that nonuniform membrane properties, along with transient dynamics of the fluid, can be leveraged to directly snap through any segment of the membrane.