Chen Mao Wei, Wu Jiang Hao, Sun Mao
School of Transportation Science and Engineering, Beihang University, Beijing, China.
Institute of Fluid Mechanics, Beihang University, Beijing, China.
PLoS One. 2017 Mar 15;12(3):e0173481. doi: 10.1371/journal.pone.0173481. eCollection 2017.
In the present paper, the controlled flight of fruitflies after voluntary takeoff is studied. Wing and body kinematics of the insects after takeoff are measured using high-speed video techniques, and the aerodynamic force and moment are calculated by the computational fluid dynamics method based on the measured data. How the control moments are generated is analyzed by correlating the computed moments with the wing kinematics. A fruit-fly has a large pitch-up angular velocity owing to the takeoff jump and the fly controls its body attitude by producing pitching moments. It is found that the pitching moment is produced by changes in both the aerodynamic force and the moment arm. The change in the aerodynamic force is mainly due to the change in angle of attack. The change in the moment arm is mainly due to the change in the mean stroke angle and deviation angle, and the deviation angle plays a more important role than the mean stroke angle in changing the moment arm (note that change in deviation angle implies variation in the position of the aerodynamic stroke plane with respect to the anatomical stroke plane). This is unlike the case of fruitflies correcting pitch perturbations in steady free flight, where they produce pitching moment mainly by changes in mean stroke angle.
在本文中，研究了果蝇在自主起飞后的受控飞行。利用高速视频技术测量昆虫起飞后的翅膀和身体运动学，并基于测量数据通过计算流体动力学方法计算气动力和力矩。通过将计算得到的力矩与翅膀运动学相关联，分析控制力矩是如何产生的。果蝇由于起飞跳跃具有较大的上仰角速度，并且通过产生俯仰力矩来控制其身体姿态。研究发现，俯仰力矩是由气动力和力臂的变化共同产生的。气动力的变化主要是由于攻角的变化。力臂的变化主要是由于平均冲程角和偏转角的变化，并且在改变力臂方面，偏转角比平均冲程角起着更重要的作用（注意，偏转角的变化意味着气动冲程平面相对于解剖学冲程平面的位置变化）。这与果蝇在稳定自由飞行中纠正俯仰扰动的情况不同，在稳定自由飞行中，它们主要通过平均冲程角的变化来产生俯仰力矩。
