A self-resetting soft ring for autonomous, continuous leaping in unstructured environments

Continuous leaping is an effective locomotion strategy for traversing cluttered and unstructured environments. However, achieving autonomous continuous leaping in soft machines remains challenging because it requires recyclable energy storage and release, reliable self-resetting for relaunch, aerial stability, and adaptability across diverse terrains. Here, we report a self-resetting soft ring jumper capable of autonomous, continuous, and stable horizontal leaping under constant infrared illumination. The jumper consists of a photothermally responsive liquid crystal elastomer ring integrated with a rigid V-shaped tail. Under illumination, the soft ring self-twists to store elastic energy while simultaneously inducing out-of-plane bending of the tail through geometric constraints imposed by the rigid tail. Once a critical threshold is reached, snapping of the rotating rigid tail against the ground launches the ring into the air. During flight, the ring autonomously untwists to recover its original shape and self-resets, enabling repeated cycles of energy storage, release, and relaunch. The snapping mechanism and full leaping dynamics are captured by combined static and dynamic Cosserat-rod models. By tuning geometric asymmetry and the center of mass, the jumper transitions among crawling, directional leaping, and vertical jumping. Optimized designs achieve vertical jumps exceeding 80 body heights and directional leaps over 3 body lengths. Beyond controlled motion on flat surfaces, the jumper demonstrates resilient multimodal locomotion across slopes, parallel hurdles, water-land interfaces, and diverse natural terrains including grass, sand, rocks, mulch, and water surfaces. This work can find potential applications in environmental navigation, swarm robotics, and unstructured terrain navigation.