撓性與旋轉角於大白斑蝶及仿蝴蝶拍撲機構升力之影響

Abstract

本文整合生物實驗、仿蝴蝶飛行器機構設計及PIV流場解析，探討真實蝴蝶主動旋轉有撓性的翅膀對飛行產生巨大影響，期望獲得能量效益較佳、飛行相對穩定之動作策略，供微飛行器設計參考。研究結果顯示，具適當剛性程度之翅膀，翅膀受力變形形成被動旋轉，使升力振幅降低，同時使其主動對稱旋轉具有較佳之平均升力，且主動旋轉增加之功耗十分微小，可為飛行器設計之依據。 本文首先以兩台正交高速攝影機拍攝大白斑蝶(Idea leuconoe)飛行動態，動態分析其翅膀拍動與翼根旋轉變換方向之時間，大白斑蝶變換時間相同則稱為對稱旋轉，其翼根旋轉振幅約15°，且動態觀測翅膀拍動會因受力而彎曲。其次參考蝴蝶翅膀外形與其運動，設計可獨立控制翅膀三個旋轉軸之仿蝴蝶飛行機構。接著分別以翅膀材料差異與控制翅膀轉軸之相位，於機構上探討被動與主動旋轉對升力的影響，與控制馬達主動旋轉之能量效益與升力的關係。 翅膀材料選用碳纖維、PLA及PETG翅膀，其剛性程度分別為最高、適中及最低。六分量平衡儀測得剛性程度越低則升力振幅越小。碳纖翅膀在領先旋轉(翼根旋轉變換早於翅膀反向拍動)有最大升力，但其振幅大，機構會劇烈震動而提高損壞風險。受力變形之翅膀於對稱旋轉能提升平均升力，又以PLA翅膀提升升力約40%為最佳，且振幅較小可提升飛行穩定性。PIV流場可視化觀測顯示被動旋轉可使渦漩持續貼附，配合不同剛性程度翅膀與旋轉相位能提高渦漩強度而提升升力;增加翼根主動旋轉，其功耗與升力之比值優於無旋轉。 本研究由真實生物之飛行策略獲得設計機構之靈感，從六分量平衡儀測量與粒子影像測速法，分析翼根旋轉與翅膀拍動相位和翅膀剛性程度之關聯，並將馬達效率納入考量。結果發現仿生機構與蝴蝶飛行策略相同時，配合對稱旋轉之適當剛性翅膀有最佳平均升力與較小的升力振幅。

It has a huge impact on the lift for real butterfly to rotate the wings actively with its flexibility. Therefore, the purpose of this research is to explore the lift and the motor energy efficiency using the mechanism with three degree of freedom inspired by the wing’s shape and movement of Idea leuconoe on forward flight with different rotation mode, including active rotation and the passive rotation by wing’s flexibility. Orthogonally-aligned high speed cameras are used to capture the dynamics of the butterfly. It was found that their wings would bend due to force and the phase of flapping and rotating angle was advanced rotation. Then make the mechanism with the wings made of carbon fiber, PLA and PETG wings. Their rigidity is the highest, moderate and lowest respectively. The result shows that carbon wing has the maximum instantaneous lift at advanced rotation but larger lift amplitude during one flapping cycle. The larger lift amplitude would increase the risk of damage with vibrate violently. PLA wing with symmetric rotation has the second largest average lift and smaller lift amplitude. Passive and active rotation coupling can obtain the better lift, and at the same time have a smaller lift amplitude. In this study, the flight strategy of real butterflies was inspired by the design agency, and the relationship between the degree of wing rigidity and the phase of rotaion and flapping angle was analyzed from the measurement of the six-component balance, the particle image velocimetry, and the motor efficiency was taken into consideration. This study believes that the appropriate flexible wings with symmetrical rotation have the best average lift and smaller lift amplitude, which can be used as a reference for the subsequent design of the bionic micro-aircraft.