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Coupled Rigid Bodies, Impulsive Dynamics, Applications - Trap Jaw Ants, Leaping Lizards, Falling Cat

Ross Dynamics Lab via YouTube

Overview

Explore advanced dynamics applications in this 55-minute lecture covering coupled rigid bodies, impulsive dynamics, and fascinating biological systems. Delve into the unusual behavior of rolling and spinning bodies, multi-rigid body systems like the acrobot, and conservation of angular momentum with examples ranging from astronaut reorientation to how cats land on their feet. Examine gyro-stabilization in ships and spacecraft, impact dynamics in passive dynamic walking and jumping toys, and the ballistic jaw propulsion of trap-jaw ants. Conclude with an analysis of continuous systems with changing geometry, such as flying snakes, modeled as quasi-rigid bodies. Gain insights into the intersection of physics and biology, with potential applications in robotics and engineering design.

Syllabus

Get it?.
Introduction of topics.
Unusual behavior of rolling and spinning bodies, like the tippe top and a spinning egg.
Coupled, multi-rigid body systems, such as the acrobot (acrobat robot on the high bar).
Conservation of angular momentum and interesting applications, such as astronaut reorientation in space ("Elroy's beanie"), tail-assisted pitch control of jumping lizards (suggesting the use of tails for robots), how cats land on their feet, and pitch control of cars in a jump off a ramp. The jumping lizards material is from http://doi.org/10.1038/nature10710.
Gyro-stabilization of ships (watercraft rocking due to waves) and control momentum gyroscopes for spacecraft. The company that makes the ship-stabilizing gyro is https://www.seakeeper.com.
Impact dynamics or impulsive dynamics, instantaneous dynamics vs. continuous dynamics. Applications include passive dynamic walking (of a simple compass bipedal walker), jumping popper toy (quick release of stored elastic energy), and ballistic jaw propulsion of trap-jaw ants ("ejection seat"). More about trap-jaw ants from Sheila Patek's paper: https://www.pnas.org/content/pnas/103/34/12787.full.pdf.
Continuous systems of changing geometry modeled as quasi-rigid bodies (that is bodies with time-varying geometry) with time-varying moment of inertia, e.g., the flying snake. More about flying snake modeling: https://youtu.be/0PQ1_XpjBso.

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Ross Dynamics Lab

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