Snakes primarily climb trees and other rough surfaces. Snake skin has ... Snakes use the
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Preparation material foridea generationat 7:30am May 2003 Motohide Hatanaka Center for Design Research Stanford University, USA
Contents • What do animals do? • Insects (Kevin Hufford) • Small Mammals (Dan Santos) • Rock Climbers (Trey McClung) • Mollusks (SangBae Kim) • Snakes (Miguel Piedrahita) • Birds (Motohide Hatanaka) • Climbing scenario
Contents (for printouts) • Tasks identified and conceptual solutions • Horizontal-vertical-horizontal transition • Thrusting inward and outward • Prevent fall off • Creating surface normal force • Hugging force • What if you fall? • Parameter optimization & sensitivity analysis (2 sets of copied notes)
Insects (Kevin Hufford) Kevin and his fishhook-clawed foot
Thin-film Adhesion Arolium Cockroach: Linked to claws Ant: Linked to claws and may also be extended independently Secretion pores on arolium Federle, W., E. L. Brainerd, T. A. McMahon, and B. Hölldobler. 2001. Biomechanics of the movable pretarsal adhesive organ in ants and bees. Proceedings of the National Academy of Sciences, USA 98:6215-6220. http://www.bio.umass.edu/biology/brainerd/pdf/Brainerd-2001-PNAS.pdf
Cockroach Foot http://www.lclark.edu/~autumn/climbing/hybrid.html
Thin-film Adhesion Palmetto tortoise beetle (Hemisphaerota cyanea) • 10,000 bristles per foot • 200x its own weight • for short periods http://creatures.ifas.ufl.edu/orn/palms/hemisphaerota_cyanea.htm
Thin-film Adhesion Palmetto tortoise beetle (Hemisphaerota cyanea) White arrows point to secretion pores at base of bristles (C) Oily footprints left by normal walking; (D) Prints left after clinging to surface Eisner, T., and D. J. Aneshansley. 2000. Defense by foot adhesion in a beetle (Hemisphaerota cyanea). Proceedings of the National Academy of Sciences, USA 97:6568-6573. HTML: http://www.pnas.org/cgi/content/full/97/12/6568 PDF: http://www.pnas.org/cgi/reprint/97/12/6568.pdf Clumped bristles conduct oily fluid to tips; Spread bristles make contact and seal off pores.
Forelimbs and Claws provide Normal Force keeping animal falling back Hind limbs use normal force to provide thrust to climb Clawed Animals:Squirrels, Possums, etc.
Adaptation on some Arboreal animals which allows controlled climbing downward. No new joints to reverse foot. Extra-extension of existing joints. Hind Foot Reversal
Human Climbing • Humans usually use aids http://news.bbc.co.uk/1/hi/sci/tech/1334582.stm • Passive (pic & link?) • Active (pic & link?) • Clever hand moves http://chvc2.netfirms.com/climb.htm • Mostly used to pull body normal to surface • Sometimes arms used to lift • Tire easier than legs • Open grip, crimp, finger-lock, jamming (finger, hand, fist) (pics) • Foot use • Inside, outside toe (pic?) • Legs mostly used for lifting • Climbing uses twice the energy required for walking Elton et al (1998). Habitual energy expenditure of human climbing and clambering. Annals of Human Biology 25: (6) 523-5
Active Aids Passive Aids LINKS http://www.sportextreme.com/Se_Shop/HTC/Climbing/CammingDevices/CammingDevices.page.KategoriID.211_index.html http://www.sportextreme.com/Se_Shop/HTC/Climbing/Nuts_brass_hex/Nuts_brass_hex.page.KategoriID.211_index.html
Finger Jam Fist Jam Keep COM near body center Hand Jam Foot use Graphics from: http://chvc2.netfirms.com/climb.htm Pictures from: http://sun-valley.stanford.edu/papers/BretlMRL:2003.pdf OR http://arl.stanford.edu/~tbretl/publications.html
How snails move.. http://members.lycos.co.uk/Mollusks/index.html
Snail Anatomy The snail's musculous foot is it's main locomotive organ. The foot is almost all of the snail's soft body visible outside the shell...
Undulating Muscle Contraction • Four tentacles that each can be withdrawn by an own retractor muscle…. On the foot's sole side there are mucus glands that produce the slime snails crawl on. The snail's slime trace reduces the friction between it's foot sole and the ground. Locomotion takes place by undulating movements of the foot sole running from back to the snail's front. Video clip of moving snail
Snail’s Foot • Undulating foot – wave of muscle contraction moves forward. • Stationary foot – minimize loss of mucus making thin film on the ground. Undulating foot Stationary foot
Mucus of Snail • Mucus of snail produce sticking force • Flexible body fit on various ground surface and produce capillary force (viscosity high
http://members.lycos.co.uk/Mollusks/index.html Mucus reduce water loss.. The thick skin on the back and sides of the body also contains large numbers of mucous glands. Mucous released in to the network of furrows between the tubercles (small bumps on the skin) spreads over the whole of the animal's body, so that the evaporation of water from the animal's skin is reduced
Snake Climbing • Several snake species are good climbers, particularly the rat snake. • Snakes primarily climb trees and other rough surfaces. • Snake skin has flexible “pawls” at nanoscale level, which provide frictional anisotropy: low friction for forward sliding and high friction for backward motion. • The cross-section of these snakes is optimized for climbing:
Concertina Locomotion • Snakes use the “concertina” method of locomotion to climb both up and down. • Body is drawn into a series of pleats, with each pleat draped over an available projection. • To climb, the pleats at the front open out and the snake’s head reaches forward until a new purchase point is found. Then new folds are formed at the head end, and these folds begin to travel backward along the snake’s body. • Scales play a minor role in climbing
Birds flap wings to increase ground reaction force traction Traction = N = static friction coefficient N= surface normal force Think of increasing both andN Kenneth Dial, Wing-Assisted Incline Running and the Evolution of Flight. Science 299, 402-4 (2003)
Balancing fore-limb pull and foot/tail support Vertical force balance: Forelimb pull + foot support + tail support = -(gravitational force) Horizontal force balance: forelimb pull = -(foot pressure + tail pressure Chatterjee Sankar, The Rise of Birds. The Johns Hopkins University Press, Baltimore, Maryland, 1997.
We didn’t prepare any slides, but... Sean Bailey Jonathan Clark