Pete Ashley E, Kress Daniel, Dimitrov Marina A, Lentink David
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
J R Soc Interface. 2015 Sep 6;12(110):0508. doi: 10.1098/rsif.2015.0508.
Birds improve vision by stabilizing head position relative to their surroundings, while their body is forced up and down during flapping flight. Stabilization is facilitated by compensatory motion of the sophisticated avian head-neck system. While relative head motion has been studied in stationary and walking birds, little is known about how birds accomplish head stabilization during flapping flight. To unravel this, we approximate the avian neck with a linear mass-spring-damper system for vertical displacements, analogous to proven head stabilization models for walking humans. We corroborate the model's dimensionless natural frequency and damping ratios from high-speed video recordings of whooper swans (Cygnus cygnus) flying over a lake. The data show that flap-induced body oscillations can be passively attenuated through the neck. We find that the passive model robustly attenuates large body oscillations, even in response to head mass and gust perturbations. Our proof of principle shows that bird-inspired drones with flapping wings could record better images with a swan-inspired passive camera suspension.
鸟类通过相对于周围环境稳定头部位置来改善视力，而在扑翼飞行过程中它们的身体会上下起伏。复杂的鸟类头颈系统的补偿运动有助于实现稳定。虽然已经对静止和行走的鸟类的相对头部运动进行了研究，但对于鸟类在扑翼飞行过程中如何实现头部稳定却知之甚少。为了弄清楚这一点，我们用一个线性质量 - 弹簧 - 阻尼系统来近似鸟类的颈部垂直位移，类似于已证实的人类行走时的头部稳定模型。我们通过对在湖面上方飞行的大天鹅（Cygnus cygnus）的高速视频记录来验证该模型的无量纲固有频率和阻尼比。数据表明，扑翼引起的身体振荡可以通过颈部被动衰减。我们发现，即使响应头部质量和阵风扰动，被动模型也能有力地衰减大的身体振荡。我们的原理证明表明，具有扑翼的受鸟类启发的无人机可以通过受天鹅启发的被动相机悬架记录更好的图像。
