Experimental Investigation of Locomotive Efficiency of a Soft Robotic Eel with a Largely Passive Body

Dinh Quang Nguyen, Van Anh Ho

Abstract: In this paper, the swimming efficiency of a soft elongated robot with a largely passive body was evaluated. The previously developed robot was constituted of a series of soft actuators, and we assumed that half of the soft eel robot’s body was uncontrolled. In this case, only the head segment plays the role of the wave source, and the rest becomes the wave propagation parts. Four values of tail beat frequencies were chosen from 0.83 Hz to 1.67 Hz, while the maximum pressure of head segment was varied from 40 kPa to 75 kPa. The swimming velocity increases corresponding to the rise of the head segment’s inner pressure and reaches a peak at 65 kPa, followed by decrements of the speed. We observed that the soft eel robot performed the best swimming efficiency at 1.0 Hz with the highest velocity of 12.46 cm/s (or 0.235 BL/s (Body Length per second)), with lowest COT (cost of transport) of 9.39. The results in this paper can be utilized to enlarge the working conditions of the soft elongated robot body even when the body is partly damaged.