School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA.
J R Soc Interface. 2011 Oct 7;8(63):1480-6. doi: 10.1098/rsif.2011.0019. Epub 2011 Apr 6.
The analysis of terrestrial locomotion over the past half century has focused largely on strategies of mechanical energy recovery used during walking and running. In contrast, we describe the underlying mechanics of legged locomotion as a collision-like interaction that redirects the centre of mass (CoM). We introduce the collision angle, determined by the angle between the CoM force and velocity vectors, and show by computing the collision fraction, a ratio of actual to potential collision, that the quadrupedal walk and gallop employ collision-reduction strategies while the trot permits greater collisions. We provide the first experimental evidence that a collision-based approach can differentiate quadrupedal gaits and quantify interspecific differences. Furthermore, we show that this approach explains the physical basis of a commonly used locomotion metric, the mechanical cost of transport. Collision angle and collision fraction provide a unifying analysis of legged locomotion which can be applied broadly across animal size, leg number and gait.
在过去的半个世纪中，对陆地运动的分析主要集中在行走和奔跑过程中机械能量回收的策略上。相比之下，我们将腿部运动的基础力学描述为一种类似碰撞的相互作用，这种相互作用会改变质心（CoM）的方向。我们引入了碰撞角，由 CoM 力和速度矢量之间的夹角确定，并通过计算碰撞分数（实际碰撞与潜在碰撞的比值）来表明，四足行走和奔跑采用了减少碰撞的策略，而小跑则允许更大的碰撞。我们提供了第一个实验证据，证明基于碰撞的方法可以区分四足步态并量化种间差异。此外，我们还表明，这种方法解释了一种常用运动度量的物理基础，即运输的机械成本。碰撞角和碰撞分数为腿部运动提供了一种统一的分析方法，可广泛应用于动物体型、腿部数量和步态。
