Abstract

The study of biomimetic robotic fish has received a growing amount of research interest in the past several years. This thesis describes the development and testing of a novel mechanical design of a biomimetic robotic fish. The robotic fish has a structure which uses oscillating caudal fins and a pair of pectoral fins to generate fish-like swimming motion. This unique design enables the robotic fish to swim in two swimming modes, namely Body/Caudal Fin (BCF) and Median/Paired Fin (MPF). In order to combine BCF mode with MPF mode, the robotic fish utilizes a flexible posterior body, an oscillating foil actuated by three servomotors, and one pair of pectoral fins individually driven by four servomotors. Effective servo motions and swimming gaits are then proposed to control its swimming behaviour. Based on these results, fish-like swimming can be achieved including forward, backward, and turning motions. An experimental setup for the robotic fish was implemented using machine vision position and velocity measurement. The experimental results show that the robotic fish performed well in terms of manoeuvrability and cruise speed. Based on the experimental data, a low order dynamic model is proposed and identified. Together, these results provide an experimental framework for development of new modelling and control techniques for biomimetic robotic fish.