College of Mechanical Engineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou 310014, China.
College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016, China.
J Exp Biol. 2024 Jun 1;227(11). doi: 10.1242/jeb.246931. Epub 2024 Jun 7.
Secure landing is indispensable for both leaping animals and robotics. Tree frogs, renowned for their adhesive capabilities, can effectively jump across intricate 3D terrain and land safely. Compared with jumping, the mechanisms underlying their landing technique, particularly in arboreal environments, have remained largely unknown. In this study, we focused on the landing patterns of the tree frog Polypedates dennysi on horizontally placed perches, explicitly emphasizing the influence of perch diameters. Tree frogs demonstrated diverse landing postures, including the utilization of: (1) single front foot, (2) double front feet, (3) anterior bellies, (4) middle bellies, (5) posterior bellies, (6) single hind foot, or (5) double hind feet. Generally, tree frogs favoured bellies on slimmer targets but double front feet on large perches. Analysis of limb-trunk relationships revealed their adaptability to modify postures, including body positions and limb orientations, for successful landing. The variations in the initial landing postures affected the subsequent landing procedures and, consequently, the dynamics. As the initial contact position switched from front foot back to the hind foot, the stabilization time decreased at first, reaching a minimum in middle belly landings, and then increased again. The maximum vertical forces showed an inverse trend, whereas the maximum fore-aft forces continuously increased as the initial contact position switched. As the perch diameter increased, the time expended dropped, whereas the maximum impact force increased. These findings not only add to our understanding of frog landings but also highlight the necessity of considering perch diameters and landing styles when studying the biomechanics of arboreal locomotion.
安全着陆对跳跃动物和机器人来说都是必不可少的。树蛙以其粘性能力而闻名，它们可以有效地跳跃复杂的 3D 地形并安全着陆。与跳跃相比，它们着陆技术的机制，特别是在树木环境中的机制，仍然知之甚少。在这项研究中，我们专注于树蛙 Polypedates dennysi 在水平放置的栖木上的着陆模式，特别强调了栖木直径的影响。树蛙表现出多种着陆姿势，包括：（1）单前脚，（2）双前脚，（3）前腹部，（4）中腹部，（5）后腹部，（6）单后脚或（5）双后脚。通常，树蛙更喜欢在较细的目标上使用腹部，但在较大的栖木上则更喜欢使用双前脚。对肢体-树干关系的分析表明，它们能够适应修改姿势，包括身体位置和肢体方向，以实现成功着陆。初始着陆姿势的变化会影响后续的着陆程序，并因此影响动力学。随着初始接触位置从前脚向后脚切换，稳定时间先减少，在中腹部着陆时达到最小值，然后再次增加。最大垂直力呈相反趋势，而最大前后力随着初始接触位置的切换而持续增加。随着栖木直径的增加，所花费的时间减少，而最大冲击力增加。这些发现不仅增加了我们对青蛙着陆的理解，还强调了在研究树木运动的生物力学时需要考虑栖木直径和着陆方式。
