High Center-of-Mass, Multi-Legged Soft Robots Powered by Geometrically Encoded Liquid Crystal Elastomer Arc Appendages

Abstract

Biological appendages are paramount for locomotion by combining high compliance and versatile maneuverability. Yet most soft robots are largely confined to the contact surface due to their appendage-free and single-mode deformation, resulting in a low center-of-mass (CoM) and limited postural/spatial mobility. Here, we create soft robots utilizing liquid crystal elastomer (LCE) arc fibers as appendages to emulate the complex maneuvers of their biological counterparts. Geometrically encoding combined torsional and flexural modes allows these robots to transcend surface constraints via a naturally elevated CoM and enhanced maneuverability. Leveraging the kinetics and thermodynamics of the fiber deformation-recovery cycles, we integrate the encoded fibers into the 3D-printed body with vertical and horizontal rotational symmetries, inspired by the locomotion of the octopus and the golden wheel spider, respectively. Our model can elevate, lower, tilt, and rotate with substantial postural freedom. It can also be engineered to roll at 1.3 body lengths per second, climb a 32.5° incline, and traverse unstructured terrain. These feats are enabled by the large inertia generated by the inherent instability of the raised CoM and the effective ground anchoring of the appendages. These insights lay the foundation for customizable, high-mobility soft robotic platforms that navigate complex real-world environments.