Thrust Improvement of a Biomimetic Robotic Fish by Using a Deformable Caudal Fin

Abstract

In nature, live fish has various deformable fins which are capable to promote the swimming speed, efficiency, stability, and thrust generation. However, this feature is rarely possessed by current man-made biomimetic robotic fishes. In this paper, a novel deformable caudal fin platform is proposed to improve thrust generation of biomimetic robotic fish. First, the design of the deformable caudal fin is given, which includes a servo motor, a gear-based transmission mechanism, fin bones, and silica membrane. Second, an improved Central Pattern Generator (CPG) model was developed to coordinately control the flapping of the tail and the deformation of the caudal fin. More specifically, three deformation patterns, i.e., conventional nondeformable mode, sinusoidal-based mode, instant mode, of the caudal fin are investigated. Third, extensive experiments are conducted to explore the effects of deformation of the caudal fin on the thrust generation of the biomimetic robotic fish. It was found that the instant mode of the caudal fin has the largest thrust, which sees a 27.5% improvement compared to the conventional nondeformable mode, followed by the sinusoidal-based mode, which also sees an 18.2% improvement. This work provides a novel way to design and control the deformation of the caudal fin, which sheds light on the development of high-performance biomimetic robotic fish.

A Novel Untethered Robotic Fish with an Actively Deformable Caudal Fin

“…The design and functionality of the deformable caudal fin are described in detail in another study. [ 26 ] It deforms in the vertical plane of the robotic fish. Notably, this implementation represents the first instance of an actively deformable caudal fin being applied to an untethered biomimetic robotic fish.…”

“…In our previous work, we proposed an actively deformable caudal fin and investigated three deformation modes in terms of thrust. [ 26 ] Building upon this research, the present study introduces a novel untethered robotic fish driven by the actively deformable caudal fin. This work makes two key contributions.…”

Quantifying the Leaping Motion Using a Self-Propelled Bionic Robotic Dolphin Platform

“…When a body moves near the water surface at high speed, the wave-making resistance becomes the primary drag, consuming energy very evidently [ 19 , 20 ]. Extensive investigations on the propulsion efficiency of robotic fish, including system design and control optimization, were conducted in [ 21 , 22 , 23 , 24 , 25 ]. The influences of wave-making resistance on the propulsion performance of a bionic robotic dolphin has been less analyzed.…”