10.28.2009 - Hu on Snakes

    • Biological diversity
      • Static stability <-Most animals
        • Average size: small (beetle size)
        • Average legs: six
      • Dynamic stability <-Few animals
    • Snake movement
      • Undulation
      • Sidewinding
      • Ratcheting
      • Concertina
    • Most experiments have snakes move through pegs
      • Snakes can move without normal forces to lateral parts of body
    • Snakes change gate based on the friction coefficient of the ground
    • Model employed in the talk assumes sliding friction only (coulomb friction)
    • Snake has very low inertia - when it stops moving it doesn't keep moving
    • The dynamics of the snake were written in terms of the kinematics of the snakes assumed shape
    • Speed is dependent on the ratio of forward-to-sidwards friction coefficient
    • Since friction is the method of motion weight distribution is very important
    • Snakes may also employ "active friction"