origami, linkages, and polyhedra
TRANSCRIPT
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Erik DemaineErik Demaine, MIT, MIT
Folding Folding withwith AlgorithmsAlgorithms
Origami,Origami, Linkages,Linkages,& Polyhedra:& Polyhedra:
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New BookNew Book
• www.gfalop.org• Appearing
this month• Cambridge
UniversityPress
• ~600 pages
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Geometric FoldingGeometric Folding
Linkages(1D)
Paper(2D)
Polyhedra(3D)
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Folding is Everywhere:Folding is Everywhere:LinkagesLinkages
RoboticsMechanics
Graphics Biology
[CanadArm]
HIV protease
[Leclercq, Akkouche, Galin2001]
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Folding is Everywhere:Folding is Everywhere:PaperPaper
Airbags
Origami Deployable structures
[Hercules Beetle, opus 424, Robert Lang]
[BRL Inc]
[You & Kuriba-yashi2003]
[Lang & LLNL2002]
5m →100m
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Folding is Everywhere:Folding is Everywhere:PolyhedraPolyhedra
Sheet-metalmanufacturing
Reconfigurable robotics,self-assembly, nanomanufacturing
[Lundström Design][Daniela Rus et al.]
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Geometric FoldingGeometric Folding
Linkages(1D)
Paper(2D)
Polyhedra(3D)
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LinkagesLinkages
Peaucellier 1864
Watt 1764
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Basic Questions about LinkagesBasic Questions about Linkages
Given a linkage…
• Rigidity:▪Does the linkage move at all?
• Universality:▪Into what configurations can it fold?
• Motion planning:▪How do we get there?
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RigidityRigidity
• What linkages can move at all?• Rigid frameworks: buildings, bridges, etc.
[Big Dig in Boston][Chubynsky, Hespenheide, Jacobs, Kuhn, Lei,
Menor, Rader, Thorpe, Whiteley, Zavodszky 2003]
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RigidityRigidity
• What linkages can move at all?▪Known: Characterization in 2D [Laman 1970]▪Unsolved: Most problems in 3D
Flexible
Rigid Rigid
Rigid
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UniversalityUniversality
• Can a linkage move universally betweenany two configurations?
Wire bendingHydraulic tube
bendingRobotic arm
folding
AIM Inc
Horn Machine Tools CanadArm
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UniversalityUniversality
• Can a chain linkage move universally between any two configurations?▪Yes in 2D
[Connelly, Demaine, Rote — FOCS 2000]▪No in 3D
[Cantarella & Johnston 1998] ▪Yes in 4D
[Cocan & O’Rourke 2002]
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Universality: Unfolding 2D ChainsUniversality: Unfolding 2D Chains[[CantarellaCantarella, Demaine, , Demaine, IbenIben, O’Brien , O’Brien —— SoCGSoCG 2004]2004]
spiral
spider
tentacle
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Motion PlanningMotion Planning[[IbenIben, O’Brien, Demaine, O’Brien, Demaine —— SIGGRAPH 2004, SIGGRAPH 2004, SoCGSoCG 2006]2006]
• Find short motion from A to B (if possible)• Universality results give new insight into
cases of interest, e.g., polygon morphing
→ ? →
→ ? →
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Challenge in 3DChallenge in 3D
• 3D chains can be locked:[Cantarella & Johnston 1998]
• Unsolved: Which 3D chains are locked?• Known: Motion planning of 3D chains
is computationally intractable[Alt, Knauer, Rote, Whitesides 2004]
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ProteinsProteins
• DNA encodes proteins ingenetic code
• Proteins are “fundamental building blocks of life”
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ProteinProteinFoldingFolding
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Importance of Protein FoldingImportance of Protein Folding
• Geometry of a protein folding is an important aspect of its behavior
• Prediction of protein folding, and synthesis of proteins with desired foldings, are central problems in computational biology▪Drug design▪ Preventing diseases (e.g., Alzheimer’s,
mad-cow disease, cystic fibrosis,some forms of cancer)
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Mechanics of Protein FoldingMechanics of Protein Folding
• Protein backbone is roughly a 3D chainwith fixed-angle constraints
• Natural question:▪3D chains are hard to fold▪How does nature fold
proteins so easily?
… …
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Mechanics of Protein FoldingMechanics of Protein Folding
• Why do proteins fold easily?• Possible answer:
▪Ribosome constructsproteins, enforcinggeometric constraints
[Nissen, Hansen, Ban, Moore, Steitz— Science 2000]
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Mechanics of Protein FoldingMechanics of Protein Folding
• Why do proteins fold easily?• Possible answer:
▪Ribosome constructsproteins, enforcinggeometric constraints
• Cone model: [Demaine,Langerman, O’Rourke 2006]▪All producible states
can reach each other▪Flattenable▪Helical canonical state
q0
α
z
x
y
Cα
Bα
ribosome
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Geometric FoldingGeometric Folding
Linkages(1D)
Paper(2D)
Polyhedra(3D)
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OrigamiOrigami
• Perhaps as old as paper itself (105 AD)• Revolution in complex
origami design overpast ~25 years
Joel CooperSatoshi Kamiya
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Pangolin by Eric Joisel
Bat byMichael LaFosse
BlackForestCuckooClock byRobert Lang
Mask by Eric Joisel
Photos fromOrigamido:
Masterworks ofPaper Folding
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Tree Frog, opus 280 Koi, opus 425
Models & photosby Robert Lang
Dancers,opp. 457 & 458 Hermit Crab
Mt Diablo Tarantula, opus 481
Roosevelt Elk,opus 358
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2006 Design ChallengePhotos by Brian Chan
Brian Chan
Robert LangGiang Dinh
Jason Ku
Andrea Hawksley
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Origami Mathematics & AlgorithmsOrigami Mathematics & Algorithms
• Explosion in technical origami thanksin part to growing mathematical and computational understanding of origami
GargoyleJason Ku
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Origami Mathematics & AlgorithmsOrigami Mathematics & Algorithms
• Theorem: Any 2D or 3D shapecan be folded from a square of paper[Demaine, Demaine, Mitchell 1999]
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Origami Mathematics & AlgorithmsOrigami Mathematics & Algorithms
• Algorithm to fold optimal origami “base” with desired stick-figure projection[Lang 1996–2006; Lang & Demaine 2006]
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?
Folded States vs. Folding MotionsFolded States vs. Folding Motions
• Folded state = origami model• Folding motion = how you got there
crease pattern folded statefolding motion
• Every folded state can be made by a folding motion: No “locked origami”[Demaine, Devadoss, Mitchell, O’Rourke 2004]
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Paper ThicknessPaper Thickness[[GalivanGalivan 2001]2001]
• Analysis of paper “loss”from repeatedlyfolding in half
• ¾-mile long paperfolds in half 12 times!
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FoldFold--andand--Cut ProblemCut Problem
• Fold a sheet of paper flat• Make one complete straight cut• Unfold the pieces
• What shapes can result?
?
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FoldFold--andand--Cut ResultCut Result
• Any collection of straight cuts can be made by folding flat & one straight cut[Demaine, Demaine, Lubiw 1998][Bern, Demaine, Eppstein, Hayes 1999]
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Deployable StructuresDeployable Structures
• Existing design ad hoc• Unsolved: techniques &
algorithms to design
[You & Kuribayashi 2003]
[Lang & LLNL2002]
5m →100m
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Origami Flashers Origami Flashers [Jeremy Shafer][Jeremy Shafer]
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Origami Flashers Origami Flashers [Jeremy Shafer][Jeremy Shafer]
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SelfSelf--Folding Origami:Folding Origami:Pleated Hyperbolic Pleated Hyperbolic ParaboloidParaboloid
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Circular Variation from BauhausCircular Variation from Bauhaus
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Circular Variations Circular Variations [Demaine & Demaine][Demaine & Demaine]
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Simulating Paper FoldingSimulating Paper Folding[Demaine, Demaine, [Demaine, Demaine, FizelFizel, , OchsendorfOchsendorf 2006]2006]
• Particle-spring simulation of forces in paper: elasticity and crease “failure”
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Geometric FoldingGeometric Folding
Linkages(1D)
Paper(2D)
Polyhedra(3D)
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Unfolding PolyhedraUnfolding Polyhedra
• Given 3D polyhedron• Cut surface & unfold• No overlap
• Goals:▪Minimum cutting
(⇒ minimum gluing)▪Efficient layout [Lundström Design]
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Theory ofTheory ofUnfolding PolyhedraUnfolding Polyhedra
• Focus on one-piece unfoldings• Convex polyhedra (no “dents”)
▪Known: Always have aone-piece unfolding[Sharir & Schorr 1986;Aronov & O’Rourke 1991]
▪Unsolved: By cuttingonly along edges?[Dürer 1525]
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Theory ofTheory ofUnfolding PolyhedraUnfolding Polyhedra
• Focus on one-piece unfoldings• Nonconvex polyhedra
▪Unsolved: Always have aone-piece unfolding?
▪Known: Not possiblejust by edge cuts[Bern, Demaine,Eppstein, Kuo,Mantler, Snoeyink 2003]
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Folding Polygons into PolyhedraFolding Polygons into Polyhedra
• Given polygon of paper• Fold arbitrarily• Glue boundary together• What convex polyhedra
can be made?
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Folding Polygons into PolyhedraFolding Polygons into Polyhedra
• Efficient algorithms to find allgluings into convex polyhedra[Demaine, Demaine, Lubiw, O’Rourke 2002]▪Unsolved: Efficient algorithms
to find actual polyhedra formed
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Reconfigurable RoboticsReconfigurable Robotics
• Crux of many reconfigurable robots is the attach/detachmechanism
• Hinged polyhedra suggest that components can remain connected[O’Rourke]
[Daniela Rus et al.]
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SelfSelf--Assembly & Assembly & NanomanufacturingNanomanufacturing
• Millimeter-scale “self-working” 2D hinged polygons[Mao, Thalladi, Wolfe, Whitesides, Whitesides 2002]
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SelfSelf--Assembly & Assembly & NanomanufacturingNanomanufacturing
• Generalization to arbitrary desired3D shapes viahinged polyhedra(currently at macro level)[Demaine, Griffith, Jacobson 2007]
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DNA FoldingDNA Folding
• Synthetic DNA to fold into desired polygon [Rothemund— Nature 2006]
~100nm