Robophysical study of jumping dynamics on granular media
Robophysical study of jumping dynamics on granular media
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DOI：
10.1038/nphys3568
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发表时间：
2016-03-01
期刊：
影响因子：
19.6
通讯作者：
Goldman, Daniel I.
中科院分区：
文献类型：
--
作者：
Aguilar, Jeffrey;Goldman, Daniel I.
表征侵入沙子和土壤的可变形物体上的力需要了解此类基底的固体和流体响应及其对物体状态的影响。对干燥颗粒介质侵入的最详细研究表明，固定形状物体在自由撞击（例如炮弹）和强制缓慢穿透过程中的相互作用可以通过类似流体静力学和流体动力学的力来描述。在这里，我们研究了一类新的颗粒相互作用：通过被动和主动方式改变形状（自我变形）的物体的快速入侵。对在干燥颗粒介质上跳跃的简单弹簧质量机器人的系统研究表明，跳跃性能是通过非线性摩擦和流体动力阻力以及诱导附加质量（传统入侵模型未考虑到的）的相互作用来解释的，其特征是脚加速的颗粒快速固化区域。包含这些动力学的模型表明，由于推离过程中最佳时机的变化，增加的质量会降低某些自变形的性能。我们的系统机器人物理实验揭示了新的软物质物理学和机器人自我变形和控制的原理，它们共同提供了可变形陆地环境中的运动原理。
Characterizing forces on deformable objects intruding into sand and soil requires understanding the solid- and fluid-like responses of such substrates and their effect on the state of the object. The most detailed studies of intrusion in dry granular media have revealed that interactions of fixed-shape objects during free impact (for example, cannonballs) and forced slow penetration can be described by hydrostatic- and hydrodynamic-like forces. Here we investigate a new class of granular interactions: rapid intrusions by objects that change shape (self-deform) through passive and active means. Systematic studies of a simple spring-mass robot jumping on dry granular media reveal that jumping performance is explained by an interplay of nonlinear frictional and hydrodynamic drag as well as induced added mass (unaccounted by traditional intrusion models) characterized by a rapidly solidified region of grains accelerated by the foot. A model incorporating these dynamics reveals that added mass degrades the performance of certain self-deformations owing to a shift in optimal timing during push-off. Our systematic robophysical experiment reveals both new soft-matter physics and principles for robotic self-deformation and control, which together provide principles of movement in deformable terrestrial environments.