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Title: | 扁平機器魚推進之動態地面效應研究 Dynamic Ground Effect on the Propulsion of a Robotic Flat-fish |
Authors: | I-Hsiang Chen 陳奕翔 |
Advisor: | 郭振華(Jen-Hwa Guo) |
Keyword: | 仿生,機器魚,側鰭,推進效率,水下技術, biomimetic,robotic fish,side fin,propulsion efficiency,underwater technology, |
Publication Year : | 2020 |
Degree: | 碩士 |
Abstract: | 本研究探討仿生型水下載具利用動態地面效應增進推進效率之方法。已知的研究顯示,當靠近固體邊界游動時,具有側鰭之扁平魚類會藉由調整側鰭擺動方式來運用與地面的距離提升推進效率。為了能運用此生物力學的概念,以提升自主式水載具的能量運用效率,本研究設計並製作一具結合側鰭與尾鰭擺動推進之扁平形機器魚。側鰭與尾鰭的作動是由多組伺服馬達驅動關節連桿達成,採用柔性扁平帶狀材料,並控制其週期振動之包絡線使呈等振幅與線性振幅兩種擺動方式,在不同波數的振動模式下,探討動態地面效應對於推進性能的影響。本研究使用理論與實驗建立側鰭之推力模式,並整合魚體、側鰭及尾鰭之動力學模型,使用文獻中所推求之動態地面效應之二維勢流理論模型近似解,求得魚體與底面距離對於推進力與推進速度之影響。理論及實驗數據顯示,機器魚在離底面不同距離下,進行等振福與線性振幅運動實驗,可驗證動態地面效應具有提升機器魚推進效率之結果。而線性振幅之側鰭擺動模式,以及側鰭之波數較大者其動態地面效應對推進效率之提升較為顯著。 The aim of this research is to develop a robotic fish of a flat-fish shape which can increase its propulsive efficiency by swimming near a solid boundary. The dynamic ground effect is a phenomenon which is known to be a hydrodynamic benefit for flat-fish while swimming near ground to gain energy efficiency. A fish mechanism which oscillates with two ribbon fins as paired side-fins and a tail fin is designed and built. The ribbon fins comprise of rigid links and a flexible material, actuated by an array of servo motors. The ribbon fins are periodically oscillating with sinusoidal functions. Kinematic conditions that define the ribbon fin swimming patterns, such as the wave number, constant and linear oscillation envelops are investigated to understand the benefits on the propulsion efficiency from the dynamic ground effect. A side-fin is modeled as a transformed oscillating dipole in two-dimensional potential flow, and approximate solutions of propulsive energy and forward velocity due to ground effect are derived using its image dipole on the opposite side of the ground. The gain in propulsion efficiency is predicted and experimentally investigated using the robotic fish near a solid ground. It is found that both theoretically predictions and experimental data show that higher efficiencies can be achieved when swimming near the ground. Higher wave numbers, and linear amplitude mode of oscillation have better propulsion efficiency. The proposed technique is expected to benefit robotic fish that swim with a close distance along a ground by increasing its propulsive efficiency. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/19210 |
DOI: | 10.6342/NTU202003790 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 工程科學及海洋工程學系 |
Files in This Item:
File | Size | Format | |
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U0001-1708202016112500.pdf Restricted Access | 3.43 MB | Adobe PDF |
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