Side-impact collision: mechanics of obstacle negotiation in sidewinding snakes
Side-impact collision: mechanics of obstacle negotiation in sidewinding snakes
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DOI：
10.1088/1748-3190/abb415
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发表时间：
2020-11-01
影响因子：
3.4
通讯作者：
Goldman, Daniel, I
中科院分区：
文献类型：
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作者：
Astley, Henry C.;Rieser, Jennifer M.;Goldman, Daniel, I
蛇擅长在杂乱的环境中移动，而异质性可以作为蛇执行横向波动的推进接触。然而，通常与沙漠有关的侧弯，在其环境中开辟了一条宽阔的道路，这可能会增加其对障碍物的脆弱性。我们之前的研究表明，侧旋可以表示为一对正交体波（垂直和水平），可以独立调制以实现高机动性和倾斜上升，这表明侧旋也可能使用模板调制来越过障碍物。为了验证这一假设，我们在头顶上录制了四条响尾蛇（Crotalus cerastes）穿过一条放置在基底上的垂直木桩线的视频。蛇有三种穿越障碍的方法：一种是传播穿越行为，在这种行为中，蛇的移动部分在木桩周围变形，并在蛇继续侧绕时被拖过去（115/160次），一种是反转转身，使蛇完全重新定向（35/160次），或者切换到手风琴运动（10/160次）。只有当静态接触的最前端区域沿着peg前方的路径传播，或者在头部附近可以形成新的静态接触区域以满足此条件时，才使用Propagate Through响应；否则，蛇只能使用反转或转换成手风琴运动。反转转弯允许蛇重新定向，或者在没有进一步接触栓的情况下逃脱，或者重新定向到一个可以使用传播通过响应的姿势。我们开发了一种算法，利用双波模板的调制在机器人物理模型中再现传播通过行为。这种行为策略为响尾蛇提供了多种选择，可以有效地绕过自然栖息地的障碍物，同时也为处理异质栖息地的机器人系统的设计和控制提供了见解。
Snakes excel at moving through cluttered environments, and heterogeneities can be used as propulsive contacts for snakes performing lateral undulation. However, sidewinding, which is often associated with sandy deserts, cuts a broad path through its environment that may increase its vulnerability to obstacles. Our prior work demonstrated that sidewinding can be represented as a pair of orthogonal body waves (vertical and horizontal) that can be independently modulated to achieve high maneuverability and incline ascent, suggesting that sidewinders may also use template modulations to negotiate obstacles. To test this hypothesis, we recorded overhead video of four sidewinder rattlesnakes (Crotalus cerastes) crossing a line of vertical pegs placed in the substrate. Snakes used three methods to traverse the obstacles: a Propagate Through behavior in which the lifted moving portion of the snake was deformed around the peg and dragged through as the snake continued sidewinding (115/160 runs), Reversal turns that reorient the snake entirely (35/160), or switching to Concertina locomotion (10/160). The Propagate Through response was only used if the anterior-most region of static contact would propagate along a path anterior to the peg, or if a new region of static contact could be formed near the head to satisfy this condition; otherwise, snakes could only use Reversal turns or switch to Concertina locomotion. Reversal turns allowed the snake to re-orient and either escape without further peg contact or re-orient into a posture amenable to using the Propagate Through response. We developed an algorithm to reproduce the Propagate Through behavior in a robophysical model using a modulation of the two-wave template. This range of behavioral strategies provides sidewinders with a versatile range of options for effectively negotiating obstacles in their natural habitat, as well as provide insights into the design and control of robotic systems dealing with heterogeneous habitats.