Design of compliant structures for aerial-aquatic robots

Abstract

Currently, tasks like water quality sampling and underwater surveying utilize copious amounts of manual labor because they either require people to deploy aquatic sensors or coordinate actions between aerial and aquatic devices. However, the development of an aerial-aquatic robot that can fly to an aquatic location, collect data, and then fly back to land could dramatically reduce the need for such costly and potentially dangerous manual labor. Unfortunately, most aerial-aquatic robots that have been developed thus far us inefficient aquatic propulsion systems that limit mission times or are unable to successfully demonstrate a full mission cycle. For this reason, improving aerial-aquatic locomotion is still an area of active research. Most aerial-aquatic robots have been inspired by nature, as there are several animals that perform aerial-aquatic maneuvers. However, current robots are limited in how well they can emulate these animals because animals have naturally soft bodies, but their robotic counterparts are made from stiff materials and structures. The focus of my research is the design and modeling of lightweight flexible structures that will ultimately enable aerial-aquatic robots to better mimic the locomotion strategies we observe in nature. Both honeycomb and kirigami structures present a promising solution to this problem as they can be used to dramatically reduce the stiffness of a stiff and lightweight material. Here, I present two projects which demonstrate how both honeycomb and kirigami structures can be used for lightweight, flexible components of aerial-aquatic robots. Both projects present work towards the development of a camber morphing airfoil which can be used for aerial locomotion by allowing for more efficient flight and aquatic motion, by acting as a morphing sail that allows the vehicle to travel at the water's surface. Both of these serve as bio-inspired locomotion strategies, as wing morphing has been observed in many birds, and camber morphing sails have been observed in Portuguese Man-o-War jellyfish. I start by deriving 1D analytical models for honeycomb and kirigami structures and then demonstrate how those structures can be used as flexible aerial-aquatic robot building blocks in a self-sensing structure intended for a camber morphing wing. I then develop 3D models for diamond celled honeycombs and then use those models to design a shape-locking camber morphing wing. Ultimately, this research demonstrates how both honeycomb and kirigami structures can be used to build flexible components of aerial-aquatic robots that enable bio-inspired designs which more accurately imitate nature.