Manufacturing and Design of Echinoderm-Inspired Underwater Soft Robots

Abstract

Echinoderms, a unique group of marine invertebrates that include sea stars and sea urchins, have emerged recently as a unique focus in the soft robotics field. These animals have unique biological actuators, symmetrical body plans, and robust adhesion mechanisms which give them the ability to deftly navigate challenging underwater or tidal typologies. This thesis aims to leverage these unique abilities by using our understanding of echinoderms to create biologically inspired mechanisms, actuators, and robots, all while developing new manufacturing processes to enable such designs. We start by developing mechanical analogues to echinoderm tube feet, which are millimeter-scale hydraulic protrusions that can chemically adhere to, and release from, objects of many shapes, forms, and compositions. We use permanent magnets embedded into fluidically-actuated bi-stable domes, whose buckling allows for high force adhesion, and a low force release mechanism on ferrous objects. This adhesion mechanism is then incorporated into cylindrical bellow-type actuators, resulting in high aspect ratio tube feet as seen on sea urchins. We further develop tube feet analogues to allow locomotion, by mechanically programming the buckling dome structure to deflect in a prescribed path. These tube feet can be used on a variety of environments, such as for walking on floors, sand, or for swimming. Looking to reduce the barriers from electronics to soft robots, we developed a novel fluidic engine that eliminates the need for traditional pumps, valves, regulators, transducers, and tanks. With this fluidic engine we then integrated a bi-directional actuator for a 270 degree range of motion, suitable for grasping or limb movement through simple electrical control. This engine lets us simplify traditional soft robot components, and we demonstrate a soft, untethered, starfish-inspired amphibious robot.