- 學位論文
利用腹部動態控制蝴蝶飛行研究
Flight Control Simulation of Butterfly with Abdominal Motion
摘要
本研究探討真實蝴蝶利用腹部操控飛行的機制，提出腹部擺動控制設計，其結果可應用於微飛行器的飛行操控上。蝴蝶飛行時，腹部會相對於身體做擺動，先前研究認為蝴蝶可以藉此控制身體的俯仰動態，進而影響拍翅方向並操控飛行。本研究利用高速攝影機記錄大白斑蝶(Idea leuconoe)的飛行動作，建立三維數值模擬，分析真實蝴蝶拍翅產生的空氣動力矩與腹部擺動對身體俯仰動態的影響，並探討如何利用腹部擺動來操控飛行。 研究結果顯示，蝴蝶前飛時，翅膀上翼前緣渦漩貼附，壓力中心位於蝴蝶質心前方；下拍時氣流相對於翅膀的來流速度較上拍時高，壓力合力大於上拍。一週期拍翅產生的總空氣動力矩大於零，會使蝴蝶失去原先的俯仰週期穩定性而墜落。本研究接著指出，腹部擺動所產生的慣性力矩數量級與拍翅產生的空氣動力矩相當，且可抑制蝴蝶一週期的俯仰角動量變化。真實蝴蝶的腹部擺動動作可降低原先平均俯仰角加速度的20.12 %，而若以擺動振幅40、相位差0.9時更可降低 61.12 %，證實了蝴蝶會藉由擺動其腹部來提升飛行時的俯仰穩定性。 為了進一步研究腹部擺動操控飛行的方法，本研究提出兩種自動控制設計：直接控制法與串聯PD控制法。模擬結果顯示，此二種控制法皆可挽回飛行墜落現象，且利用不同的目標函數，可以飛出不同的軌跡。其中，串聯PD控制考慮了質量中心、壓力中心位置以及慣性力矩效應，可在 60 的擺動振幅內達成良好的飛行控制效果；同時，擺動腹部所消耗之機械功率與拍翅相比而言極小，顯示能量使用效益優勢，以及未來應用之可實踐性。 本研究結合生物飛行、流體力學與自動控制，所提出的空氣動力矩分析與腹部動態控制設計，將來可應用於仿生拍撲微飛行器之飛行操控上。如在飛行器尾端使用雙連桿機構，並以本研究所提出的控制方法擺動，為飛行操控建立嶄新之觀點。
並列摘要
The objective of this study is to explore the mechanism of how butterflies use the abdominal motion to maneuver flight, and propose a design of an abdominal dynamics control scheme. The results can be applied to the flight control of micro aerial vehicles (MAVs). In nature, butterflies fly with significant abdominal swinging motion. It is believed that abdominal motion can change the body pitching angle, and perform different flight modes. In this study, two orthogonally-aligned high speed cameras are used to record flying kinetics data of Idea leuconoe. A 3-D numerical simulation model based on real butterflies’ geometry and mass distribution is created to analyze aerodynamics moment and the effects of abdominal motion. The results are discussed in following three sections. In the first section, because of attachment of leading-edge vortex, center of pressure (COP) is in front of center of mass (COM) of butterfly. The airflow velocity relative to the wings in downstroke is higher than that in upstroke, causing the greater pressure force generated in downstroke than that in upstroke. Aerodynamics moment consequently lead butterfly to pitch up, breaking the pitching periodic stability and cause butterfly to fall down. In the second section, it shows that the magnitude of inertial moment produced by abdominal motion is on the same order of aerodynamics moment generated by wings, and can suppress the change of pitching angular momentum. The real abdominal motion can reduce the mean pitching angular acceleration by 20.12 % and by 60.12 % with amplitude of 40 and 0.1 phase lag. It is concluded that real butterflies utilize abdominal motion to stabilize flight. In the last section, for the purpose of using abdominal motion to control flight, we design two automatic control scheme: direct control and serial proportional-derivative (serial PD) control. These two control can effectively prevent butterfly from falling down, and with different goal function, butterfly will fly in different locus. Serial PD control is designed with consideration of distance between COP and COM, and the effect of inertial moment. It can control flight within an abdominal amplitude of 60. Moreover, the mechanical power required to oscillate abdomen is much lower than that to flap wings, showing the high applicability in micro aerial vehicle (MAVs). Our results of aerodynamics moment analysis, abdominal mechanism and the design of abdominal control scheme might provide a novel method of flight control for micro aerial vehicles.