Title:
Snakes and Spiders, Robots and Geometry
Snakes and Spiders, Robots and Geometry
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Author(s)
Hatton, Ross L.
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Abstract
Locomotion and perception are common threads between
robotics and biology. Understanding these phenomena at a
mechanical level involves nonlinear dynamics and
the coordination of many degrees of freedom. In this talk, I will
discuss geometric approaches to organizing this information
in two problem domains: 1) Undulatory locomotion of snakes
and swimmers; and 2) vibration propagation in spider webs. In the first section, I will discuss how differential geometry
and Lie Group Theory provide insight into the locomotion of
undulating systems through a vocabulary of lengths, areas,
and curvatures. In particular, a tool called the Lie
Bracket combines these geometric concepts to describe the effects of cyclic changes in the locomotor’s shape, such as the
gaits used by swimming or crawling systems. Building on
these results, I will demonstrate that the geometric techniques
are useful beyond the “clean” ideal systems on which they
have traditionally been developed, and can provide insight into
the motion of systems with considerably more complex
dynamics, such as locomotors in granular media. In the second section, I will turn my attention to vibration
propagation through spiders’ webs. Due to poor eyesight,
many spiders rely on web vibrations for situational
awareness. Web-borne vibrations are used to determine the
location of prey, predators, and potential mates. The influence
of web geometry and composition on web vibrations is
important for understanding spider’s behavior and ecology.
Past studies on web vibrations have experimentally measured
the frequency response of web geometries by removing
threads from existing webs. The full influence of web structure
and tension distribution on vibration transmission; however,
has not been addressed in prior work. We have constructed
physical artificial webs and computer models to better
understand the effect of web structure on vibration
transmission. These models provide insight into the
propagation of vibrations through the webs, the frequency
response of the bare web, and the influence of the spider’s
mass and stiffness on the vibration transmission patterns.
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Date Issued
2017-04-12
Extent
52:35 minutes
Resource Type
Moving Image
Resource Subtype
Lecture