Design and Performance Study of an Underwater Soft Snake-like Robot

In this paper, we propose a design of an underwater soft snake-like robot prototype that uses two actuators made of 3D-printed soft materials to build the robot body. Control signals with appropriate displacement phases and different voltages are used to control the water pump to drive the soft actuator to bend to generate a sine wave with increasing amplitude along the body axis. We test customized tail materials, phase shifts, and voltage growth rate signals to observe the effects of different parameters on the movement of the snake robot in water. Experiments show that the movement speed is positively correlated with the swing amplitude of the snake robot's motion module. In addition, measured data show that swimming efficiency and movement speed are also affected by tail flexibility and movement gait. When the phase offset is 2/3π, the tail is made of harder PLA material, and the voltage growth rate is 1.2, the maximum underwater movement speed achieved by the snake robot is 4.464 cm/s (0.076 BL/s). We also found that when the phase offset increases, the snake motion speed and motion efficiency first increase and then decrease. The results obtained in this study will aid in the advancement of soft, slender swimming robots and improve the understanding of the swimming capabilities of both robots and sea snakes.