Experimental Performance Characterization of an Underwater Growing Robot

Soft-growing robots are an emerging field of robots that perform their growth through tip extension using a fluid flow-driven system while the robot base is stationary. With growth without relative motion with the surrounding, this can be applicable in areas of exploring constrained environments where minimum harm to the environment is required. This paper presents an experimental performance characterization of a soft underwater growing robot designed for exploring shallow water coral reef environments. The robot’s design, fabrication, and control are described, emphasizing the integration of the robot base, retraction setup, and robot body. The experiments evaluate growth velocity and tip force under various depths and flow rates. Results show consistent tip velocity across depths, with a slightly higher velocity of 14.2 mm/s at approximately 330 mm depth. The tip velocity increases with the flow rate but at a decreasing rate. The average tip force per unit length decreases with greater depth, exhibiting a nearly linear distribution from 533 mm to around 203 mm. Depths below 203 mm result in significantly higher tip forces. Through these findings, the research provides information on robot performance and advances the realization of the concept in sensitive underwater environments.