Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Mechanical Engineering | en_US |
| dc.contributor.advisor | Jing, Xingjian (ME) | en_US |
| dc.creator | Chao, Xu | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/13804 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Design, analysis, and testing of biomimetic underwater robots | en_US |
| dcterms.abstract | The ocean significantly impacts humanity by serving as a valuable source of energy and food, as well as an essential channel for maritime transport. Marine robots play an indispensable role in taking the place of human beings to carry out various activities in extreme underwater environments with respect to eliminating human risks and high adaptability to surrounding conditions. Over the decades, a variety of marine robots have been developed, including traditional thruster-driven ROVs and AUVs, as well as biomimetic swimming robots. | en_US |
| dcterms.abstract | To carry out tasks with high effectiveness and efficiency, marine robots should have extended operational durations and high agility. These capabilities hinge on the robots’ performance in energy efficiency, swimming speed, and maneuverability. It is worth noting that most fish are naturally endowed with the capability of efficient swimming as a result of millions of years’ natural selection and evolution. Approximately 85% of fish adopt the body and/or caudal fin (BCF) propulsion method, which is also a popular biomimetic approach for driving underwater robots due to its feature in dexterous and efficient swimming. However, it is rare to find swimming robots whose performance is comparable to that of their biological counterparts. Consequently, the pursuit of creating high-performance marine robots to narrow the gap with the natural skillful swimmers, fish, remains a significant focus in marine robotics research. This study aims to explore novel strategies for constructing high-performance swimming robots. | en_US |
| dcterms.abstract | In the first part, a robotic tadpole is constructed using a multi-joint-link mechanism and a compliant fin to study the effects of the active-joint ratio and the geometry-related stiffness of the fin on its swimming performance. To thoroughly and conveniently investigate the robot’s performance, the dynamic model with well-identified hydrodynamic parameters is derived. Extensive simulations and experiments are conducted to determine the optimal active-joint ratio among several designed tails, the optimal control parameters of each tail, and the optimal shape of the fin. The findings are also verified in water with currents to show the applicability in real marine environments with disturbances. | en_US |
| dcterms.abstract | Secondly, a novel stiffness modulation mechanism without introducing extra power sources is proposed to enable robotic fish to adapt to various tail beat frequencies and maintain good performance. The tail body of the robot is composed of a parallel mechanism, a rigid link, an elastic steel strip, and a slider mechanism. By controlling the rhythmic swing trajectory of the parallel mechanism, the effective length of the spring steel spanning between the rigid link and the caudal fin can be adjusted, thereby enabling the tuning of the tail’s stiffness. Numerous simulations and experiments based on the derived dynamic model demonstrate that the proposed method can effectively help the robot maintain optimal performance across a wide range of frequencies. | en_US |
| dcterms.abstract | The final part focuses on exploring nonlinear structures in the design of robotic fish to achieve efficient and agile swimming. The design integrates a flexible spine with a lightweight, parallel-linkage structure. Theoretical models are derived to facilitate the control of the robot and the understanding of its nonlinear behaviors. By actively managing the endpoint of the flexible spine, the elastic tail is endowed with remarkable controllability and adjustable bistability. Consequently, the ability to switch between monostable and bistable operational states enables the robot to demonstrate superior swimming capabilities in terms of swimming speed, energy efficiency, and maneuverability, which is validated by experimental results. | en_US |
| dcterms.extent | xix, 166 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2025 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Robots -- Motion | en_US |
| dcterms.LCSH | Fishes -- Locomotion | en_US |
| dcterms.LCSH | Biomimetics | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | open access | en_US |
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