School of Mechanical Engineering and Automation, Harbin Institute of Technology, Shenzhen, Shenzhen, People's Republic of China.
J Exp Zool A Ecol Integr Physiol. 2022 Oct;337(8):823-834. doi: 10.1002/jez.2642. Epub 2022 Jul 11.
Frogs can keep an excellent aerial balance for landing and achieve consecutive jumps reliably. A safe landing requires an accurate body righting in the air. However, there is no systematic study on how the frogs adjust the aerial postures and body attitudes after jumping. The stretched long hindlegs swung quickly in the aerial phase, which revealed a clear relationship with the body attitudes. This study aimed to verify the function of frogs' hindlegs on aero body righting in the air. We captured the motions of both hindlegs and found the hindlegs adopted two movement modes, the bilateral parallel, and separated swings. The hindleg-induced torques by the two movements were negatively correlated with the body's angular accelerations on pitch and roll, respectively. Moreover, an analytical model was derived based on the conservation of angular momentum and verified by the dynamic simulations. Thus, we confirmed that the hindlegs are the dominant mechanism in aerial pitch and roll controls. We anticipate our achievements to inspire the design of air-righting tools.
青蛙在着陆时能保持极好的空中平衡，并可靠地进行连续跳跃。安全着陆需要在空中准确地调整身体姿势。然而，目前还没有系统的研究来探讨青蛙在跳跃后如何调整空中姿势和身体姿态。伸展的长后腿在空中阶段快速摆动，这与身体姿态有明显的关系。本研究旨在验证青蛙后腿在空中进行身体姿态调整的功能。我们捕捉了后腿的运动，并发现后腿采用了两种运动模式，即双侧平行和分离摆动。两种运动引起的后腿扭矩与俯仰和滚动方向上的身体角加速度呈负相关。此外，我们还基于角动量守恒原理推导出了一个分析模型，并通过动力学模拟进行了验证。因此，我们确认后腿是空中俯仰和滚动控制的主要机制。我们期望我们的研究成果能够为空气姿态调整工具的设计提供启示。
