Soft Robotic Snake with Tunable Undulatory Gait for Efficient Underwater Locomotion

This study presents the design and experimental evaluation of a bio‐inspired underwater soft snake robot, using two 3D‐printed soft actuators to replicate anguilliform locomotion. The robot's propulsion is driven by a water pump regulated through phase‐controlled displacement signals and voltage gradients, inducing sinusoidal body undulations with increasing amplitude from head to tail. A series of experiments are conducted to investigate the influence of tail material properties, phase shift values, voltage growth rates, and undulation frequency on swimming performance. Results demonstrate a positive correlation between undulation amplitude and propulsion speed, with both speed and efficiency modulated by tail compliance and gait parameters. The highest performance is achieved with a phase offset of 2/3 π , a 3D‐printed PLA tail segment, a voltage growth rate of 1.2, and a undulation period T = 6s reaching a peak underwater speed of 4.464 cm s −1 (0.076 body lengths per second). Notably, locomotion speed increased with phase offset up to an optimal threshold, beyond which performance declined. These findings offer new insights into the mechanics of soft‐bodied aquatic locomotion and contribute to the advancement of high‐efficiency soft robotic swimmers for underwater exploration and bio‐inspired engineering.