A Novel Fish-Inspired Robot with a Double-Cam Mechanism

Zhibin Song,Zhongru Fu,Rongjie Kang,Paolo Dario,Donato Romano

doi:10.3390/machines10030190

Zhibin Song, Zhongru Fu + Show 3 more

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https://doi.org/10.3390/machines10030190

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Abstract

Fishes have evolved different excellent swimming strategies. To study the influence of tail fin swing on the swimming performance of bionic robot fish, with one joint under the same tail swing frequency and amplitude, we designed a novel robot fish, driven by a double-cam mechanism. By designing the profile of the cam in the mechanism, the robot fish can achieve different undulatory motion trajectory of the caudal fin under the same tail swing frequency and amplitude. The mechanism simulated the undulatory motion of crucian carp. We studied the influence of undulatory motion on the swimming speed of robot fish, which was analyzed by dynamic analysis of the undulatory motion and experiments. According to the experimental results, we can find that the swimming speed of the robotic fish is different under various wave motions. When other conditions are the same, the speed that the robot fish can achieve by imitating the swing motion of the real fish is 1.5 times that of the robot fish doing the cycloid motion. The experimental results correspond to the kinetic analysis results. Furthermore, it is proven that the robot fish with a low caudal peduncle stiffness swims faster under a low swinging frequency, and the speed of a robot fish with a high caudal peduncle stiffness is higher under a high tail swinging frequency.

Highlights

In the most evident group of data, the results show that the swimming speed of the robot fish can reach 1.2 BL/s under the real fish motion law at the frequency of 4 Hz
The results show that the Strouhal number of the robot fish under the real fish motion is lower than under the cycloid motion law, which indicates that the robotic fish is more efficient under the real fish motion
We explore the influence of the caudal peduncle stiffness on swimming speed, because we found that it has an inevitable influence on the swimming performances of fish robots

Summary

Introduction

Oceans represent a large genetic stock; this stock has evolved into a large variety of aquatic life, occupying almost 99% of the available living space volume, most of which remains unexplored by human beings. Underwater robots can explore oceans and aquatic environments; the main approaches comprise of main propeller and biomimetic propulsion systems. Propeller propulsion has achieved success in certain applications; the corresponding noise disturbs the environments of ocean life [2], leading to failures in monitoring and/or protecting ocean life. Bio-robots have shown good potential for being implemented (and even assimilating) into aquatic living communities. They use their super-streamlined bodies to exploit fluid-mechanical principles, achieving extraordinary propulsion efficiencies, acceleration, and maneuverability [3]

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