Manta Ray inspired multistable soft robot

Abstract

Manta rays are unique animals that exhibit complex motion behavior, given their rigid bodies and flexible fins. During turning maneuvers, these animals can hold their fins in asymmetric positions while flapping to achieve a smaller turning radius and faster-turning speed. This collective behavior can be challenging to attain using conventional soft robots or actuators. Local bistability can be leveraged to mimic this behavior by inducing spatially distributed prestress in thin, fin-like surfaces that reshape into 3D, stable configurations without the need of continuous actuation. We present a pneumatically actuated manta ray-inspired soft robot concept with multiple stable states which approximate the ray's asymmetric strokes and stroke frequency. The fins are actuated by an array of inflatable bistable and metastable dome-shaped units that allow us to independently deflect sections of the fin to achieve a desired po-sition. We tune our robot's geometry by performing a numerical parameter sweep over different geometrical configurations of the patterned dome structure. Our approach offers a new route for imposing various target 3D deflected positions of morphing surfaces with minimal actuation or feedback control by utilizing multistability.