How Non-Uniform Stiffness Affects the Propulsion Performance of a Biomimetic Robotic Fish

Abstract

Live fish in nature exhibit various stiffness characteristics. The anguilliform swimmer, like eels, has a relatively flexible body, while the thunniform swimmer, like the swordfishes, has a much stiffer body. Correspondingly, in the design of biomimetic robotic fish, how to balance the non-uniform stiffness to achieve better propulsion performance is an essential question needed to be answered. In this paper, we conduct an experimental study on this question. First, a customized experimental platform is built, which eases the adjustment of the non-uniform stiffness ratio, the stiffness of the flexible part, the flapping frequency, and the flapping amplitude. Second, extensive experiments are carried out, finding that to maximize the propulsion performance of the biomimetic robotic fish, the non-uniform stiffness ratio is required to adapt to different locomotor parameters. Specifically, the non-uniform stiffness ratio needs to be reduced when the robotic fish works at low frequency, and it needs to be increased when the robotic fish works at high frequency. Finally, detailed discussions are given to further analyze the experimental results. Overall, this study can shed light on the design of a non-uniform biomimetic robotic fish, which helps to increase its propulsion performance.

A Survey on Reinforcement Learning Methods in Bionic Underwater Robots

“…The application of bionic underwater robots, characterized by low power consumption, high maneuverability, and environmental friendliness, has become a rapidly developing research field. In the past decades, research into bionic underwater robots, by imitating the shape, swimming patterns, and behaviors of fish, has achieved promising results concerning propulsion mechanisms [ 1 , 2 ], bionic propulsion design [ 3 , 4 , 5 , 6 , 7 , 8 ], high performance optimization [ 9 , 10 , 11 , 12 ], and other aspects. Furthermore, extended research involving motion control, target tracking, and underwater navigation has been conducted for bionic underwater robots.…”