Transforming Piezoelectric Metamaterials into Functional Soft Robots

North Carolina State University, Raleigh NC

Investigators

Abstract

This grant will support research on new methods for embodying intelligence in millimeter- to centimeter-scale soft robots. These robots have a layer of flexible plastic as a frame, supporting a second layer of flexible piezoelectric polymer. Piezoelectric materials contract or expand in response to applied voltage, allowing them to be used as actuators. Alternatively, they generate a voltage when twisted or stretched, allowing them to be used as sensors instead. Configuring different regions of the piezoelectric layer as sensors or actuators, and interconnecting those regions through customized circuits, causes deformation waves to travel through the robot structure. These propagating deformations can propel the robot forward or backward, or turn the robot clockwise or counterclockwise. Different types of deformation waves might also, for example, have different heights, potentially allowing the robot to pass over an obstacle or to squeeze under a small gap. Contacting objects in the environment can change the wave propagation pattern, in turn changing the robot's motion. This project will proceed in three parts. First is a study of the different ways that deformation waves can travel in the robot structure, and how these different types of waves can be shaped and switched by different patch geometries, interconnection patterns, and contact with surrounding objects. Next is understanding how the different types of waves can be used to accomplish basic types of movements. Finally is combining these effects to achieve goals like navigating an obstacle field or escaping a maze. Ultimately these capabilities could allow many such small, flexible, low-power robots to search a disaster site for people in need of help, to monitor dry brushland for fires, or to patrol sensitive areas for intruders. The outreach activities through established summer programs and other educational initiatives will positively impact science, technology, engineering, and mathematics education of K-12 students. This research intends to bridge the fundamental knowledge gap between active mechanical metamaterials and soft robotics. It aims to embody physical intelligence in active mechanical metamaterials for creating a new class of intelligent maneuverable soft robots with reduced control burden. The new soft robots will leverage embodied materials intelligence from constituent soft electroactive polymers capable of both self-sensing and actuation, as well as mechanical intelligence from periodic architectures that localize multimodal dynamic wave modes at the boundary for distinct adaptive behaviors. This research looks to generate new knowledge on wave localization mechanisms, dynamic energy localization, and path reconfiguration. These look to enable the creation of intelligent maneuverable soft robots capable of energy efficient and robust movement through challenging terrains, as well as self-adaptive locomotion and obstacle-responsive behavior in complex unstructured environments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.