Self-Retractable Soft Growing Robots for Reliable and Fast Retraction While Preserving Their Inherent Advantages

Soft growing robots have garnered significant research interest owing to their unique locomotion. However, real-world applications of these robots are limited by challenges in achieving reversible and repeatable operations, particularly when faced with buckling during retraction. Although a variety of retraction mechanisms have been developed, many necessitate the installation of extra rigid hardware at the distal part, compromising the inherent benefits of soft growing robots. Existing soft retraction mechanisms that maintain these advantages tend to be relatively slow and rely on heavy driving fluids. This study introduces a soft retraction mechanism that depends exclusively on the existing pneumatic force, eliminating the need for additional rigid hardware, power sources, or complex control procedures. This mechanism enables rapid and reliable retraction of soft growing robots without sacrificing their inherent advantages or interfering with their inner channels during retraction. The proposed mechanism's straightforward structure facilitates easy integration with a wide range of tip mounts, steering mechanisms, and other application-specific soft growing robots. This research offers an analysis and experimental examination of the operating principles and behaviors of the proposed mechanism. It also presents the design guidelines and fabrication details for the mechanism, as well as a demonstration of its swift and buckling-free retraction. In summary, the proposed retraction mechanism holds the potential to significantly improve practical applications of soft growing robots.