Force balance in the take-off of a pierid butterfly: relative importance and timing of leg impulsion and aerodynamic forces
Force balance in the take-off of a pierid butterfly: relative importance and timing of leg impulsion and aerodynamic forces
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DOI：
10.1242/jeb.084699
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发表时间：
2013-09-01
影响因子：
2.8
通讯作者：
Godoy-Diana, Ramiro
中科院分区：
文献类型：
--
作者：
Bimbard, Gaelle;Kolomenskiy, Dmitry;Godoy-Diana, Ramiro
到目前为止，起飞阶段仍然是昆虫飞行的一个难以捉摸的阶段，与其他动作相比，对起飞阶段的探索相对较少。对起飞过程中产生力量所涉及的不同机制的全面评估从未得到探讨。专注于第一次下划，我们从蝴蝶从地面起飞的力平衡角度解决了这个问题。为了确定单一的气动翼力是否可以解释观察到的昆虫的运动，我们首先将一个简单的翼力解析模型与昆虫翅膀和身体运动的视频跟踪估计的质心加速度进行比较。其次，利用机翼运动学对气动流场进行了数值模拟。两种方法得到了相似的机翼气动力。然而，这两种方法都不足以准确地预测物体加速度，包括地面效应也不够。我们不得不求助于腿部力量来获得最适合数据的模型。我们发现，在翅膀向下拍击开始之前，中间和后腿表现出主动伸展，负责昆虫身体向上运动的开始。我们估计，在不同的时间，腿产生的向上的力可能比施加在昆虫身体上的所有其他力都要大得多。腿和翅膀力量的相对时间解释了在机动过程中观察到的轨迹的巨大变化。
Up to now, the take-off stage has remained an elusive phase of insect flight that was relatively poorly explored compared with other maneuvers. An overall assessment of the different mechanisms involved in force production during take-off has never been explored. Focusing on the first downstroke, we have addressed this problem from a force balance perspective in butterflies taking off from the ground. In order to determine whether the sole aerodynamic wing force could explain the observed motion of the insect, we have firstly compared a simple analytical model of the wing force with the acceleration of the insect's center of mass estimated from video tracking of the wing and body motions. Secondly, wing kinematics were also used for numerical simulations of the aerodynamic flow field. Similar wing aerodynamic forces were obtained by the two methods. However, neither are sufficient, nor is the inclusion of the ground effect, to predict faithfully the body acceleration. We have to resort to the leg forces to obtain a model that best fits the data. We show that the median and hind legs display an active extension responsible for the initiation of the upward motion of the insect's body, occurring before the onset of the wing downstroke. We estimate that legs generate, at various times, an upward force that can be much larger than all other forces applied to the insect's body. The relative timing of leg and wing forces explains the large variability of trajectories observed during the maneuvers.