Semester Award Granted

Summer 2025

Submission Date

August 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Thesis/Dissertation Advisor [Chair]

Oscar Curet

Abstract

The Black Ghost Knifefish achieves remarkable swimming gait transition by leveraging the distinctive morphology and kinematics of a single, elongated undular fin. Alongside bi-directional swimming, complex maneuvers incorporating vertical movement and pitch control can also be attained. Inspired by the Knifefish, we explore a novel propulsive and directional control method for an undulating membrane affixed to a robotic vessel utilizing counter-propagating waveforms in tandem with a sigmoidal spatiotemporal pattern to control forward, backward, and turning of the vessel. The proposed actuation supplied the propulsion necessary for the robotic vessel to swim bi-directionally with heading control under varying flow speed conditions. Manipulation of the colliding point of opposed propagated waves and a sigmoidal adjustment to the curvature of the fin equipped the vessel with 2D positional and heading control, allowing for both guided trajectory swimming and station-keeping when subjected to external flow disturbances. Vessel kinematics and particle image velocimetry were evaluated for detailed analysis of vessel control and resulting fluid mechanics. Refinement of undulatory swimming mechanisms offers potential for smoother navigation in AUVs, serving as ancillary propulsion to traditional rotary mechanisms or as a sole propulsive method.

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