Wing Fold and Twist Greatly Improves Flight Efficiency for Bat-Scale Flapping Wing Robots
Wing Fold and Twist Greatly Improves Flight Efficiency for Bat-Scale Flapping Wing Robots
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DOI：
10.1109/iros51168.2021.9636735
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发表时间：
2021-09
期刊：
影响因子：
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通讯作者：
Xiaozhou Fan;K. Breuer;H. Vejdani
中科院分区：
文献类型：
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作者：
Xiaozhou Fan;K. Breuer;H. Vejdani
受蝙蝠飞行性能的启发，我们探索了扑翼机器人扭转和折叠翅膀的优势。为此，我们开发了一个将这两个自由度结合到机翼上的动力学模型。假设扭转沿机翼线性增加，而机翼折叠被建模为手翼相对于臂翼的相对旋转。给出了2、5和8m/S前向飞行速度下的机翼运动学参数优化方案。讨论了机翼方向、有效攻角和随之而来的升力和推力产生之间复杂的相互作用。结果表明，机翼扭转和折叠减轻了上冲程中的负升力和负推力，在某些情况下，手翼在整个周期内都产生持续的正推力。因此，与刚性平板的底壳相比，功耗急剧下降。另一个关键的认识是，机翼的扭转和折叠在实现有效飞行方面的相对重要性强烈地取决于速度。在慢速飞行中，扭转在最小化功率方面明显更有效，但在快速飞行时会变得能量效率低下。结果还表明，在上仰过程中，45°的机翼折叠对所有速度都是有益的。机翼扭转和折叠的协同作用在慢速飞行时最为显著。这些发现为扑翼机器人的设计提供了有用的指导。
Inspired by bat flight performance, we explore the advantages of wing twist and fold for flapping wing robots. For this purpose, we develop a dynamical model that incorporates these two degrees of freedom to the wing. The twist is assumed to be linearly-increasing along the wing, while the wing fold is modeled as a relative rotation of the handwing with respect to the armwing. An optimization scheme parameterizes the wing kinematics for 2, 5 and 8 m/s forward flight velocities. The intricate interplay between wing orientation, effective angle of attack and the ensuing lift and thrust generation are discussed. The results show that wing twist and fold alleviate negative lift and thrust in the upstroke, and in some cases producing persistent positive thrust throughout cycle for handwing. As a result, power consumption drops precipitously compared to the base case of a rigid flat plate. Another crucial realization is the relative importance of wing twist and fold in achieving efficient flight strongly depends on speeds. At slow flight, twist is significantly more effective in minimizing the power, but becomes energetically inefficient for fast speeds. The results also show that a 45° wing fold during upstroke is energetically beneficial for all speeds. The synergy of wing twist and fold are most prominent at slow flight. These findings provides useful guidelines for designing flapping wing robots.