Session: Research Posters

Paper Number: 120048

120048 - Caterpillar-Inspired Soft Crawling Robot Driven by Distributed Programmable Thermal Actuation 

Soft robots have attracted wide attention in biomedical engineering, surgical assistance, active prosthetics, camouflage, and perception technologies. Lots of inspiration has been taken from the animal world to incorporate soft materials with mechanical design for soft robotics, for example, octopus, fish, snakes, worms, and caterpillars. Some unique features of these animals, including multi-modal locomotion and passing through confined gaps, can be beneficial in complex and unstructured environments. Among the various types of actuation methods, electric stimulus is one of the simplest and most convenient. For electrically stimulated actuators, bimorph thermal actuator, based on mismatch in coefficient of thermal expansion of two materials, has drawn much attention due to programmable operation, lightweight, low actuation voltage, being electrolyte-free, and potential for untethered operation. Among different thermal responsive materials, liquid crystal elastomer (LCE), a thermally driven actuating material that combines polymer network and liquid crystal mesogens, has attracted much attention because of its unique properties, including large (~40%) and reversible actuation, high processability, and programmability.

Here, we report a crawling robot that mimics the caterpillar locomotion with multiple crawling modes, controlled by joule heating of a patterned soft heater in an LCE-based thermal bimorph actuator. In this work, we used AgNWs as the heating element, embedded just below the surface of a polydimethylsiloxane (PDMS) matrix. CB powders were doped inside the PDMS precursor to enhance thermal conductivity. With distributed heating pattern and switchable conducting channels, different temperature and curvature distribution are achieved, enabling bidirectional locomotion as a result of the adjustable friction competition between the front and rear end with the ground. The thermal bimorph behavior is studied to predict and optimize the local curvature of the robot under thermal stimuli. The bidirectional actuation modes have been validated with finite element analysis (FEA) using Abaqus/CAE. The opposite sliding sequence of the two actuators is a result of different centroid location and touching angle with the ground when the robot bends to a different shape. The crawling speeds with respect to two locomotion modes, different input power and different actuation frequency have been studied. Finally, due to the symmetric two-actuator design in our crawling robot and the 2-directional locomotion capability for each actuator, we demonstrated the application of the soft crawling robot by passing through small, confined space with a much lower gap height than that of the robot. This capability of passing through small, confined space in forward and backward locomotion can be of promising potential for search and rescue. The strategy of patterned and distributed heating and actuation with thermal responsive materials offers new capabilities for smart and multifunctional soft robots.

Presenting Author: Shuang Wu North Carolina State University

Presenting Author Biography: Postdoctoral researcher at North Carolina State University. Research focus on soft and stretchable devices and soft sensors.

Authors:

Shuang Wu North Carolina State University
Yaoye Hong North Carolina State University
Yao Zhao North Carolina State University
Jie Yin North Carolina State University
Yong Zhu North Carolina State University