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Reconfiguration Mechanism Design Mark Yim Associate Professor and Gabel Family Associate Professor Dept. of Mechanical Engineering and Applied Mechanics, University of Pennsylvania There are two fundamental electro-mechanical components to self-reconfiguring robot systems
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Reconfiguration Mechanism Design Mark Yim Associate Professor and Gabel Family Associate Professor Dept. of Mechanical Engineering and Applied Mechanics, University of Pennsylvania
There are two fundamental electro-mechanical components to self-reconfiguring robot systems • An attaching/detaching mechanism • Some form of motion between reconfigurations. • Focus on hardware, however, choices in hardware effect software design and vice versa.
Costs of micro-scale device(pessimistic view) • Module: 1mm x 1mm x 1mm MEMS (silicon) • Silicon cost ~ $1/sq inch • 2003 Revenue $5.7billion / 4.78 billion sq inch silicon • $200 / 12” diam, $30 /8“ diam wafers • 100um-2000um thick (choose 1mm) • Assume processing costs ~$9/sq inch • Modules cost 1.6¢ • Synthesize human shape • Mark weighs 65 Kg -> 65,000 cm3 • Assume density of water (1kg = 1000 cm3 ) • 65,000,000 modules • 1000 modules per cm3 • Cost: $1,007,502.025
Costs of micro-scale device(optimistic view) • In mature systems, cost goes by the pound. • E.g. Xerox machines • Optimization in space/volume • The process cost can be reduced. Ultimately to near the cost of silicon (factor of 10 savings) • Fill factor of modules does not need to be 100% (factor of 10 savings) • Find a smaller person to synthesize (factor of 2 savings) • Cost $5,037
Outline • Review of Motion mechanisms • Chain style reconfiguration • Lattice style reconfiguration • Review of Latching mechanisms • Discussion
Three Classes of Existing Self-Reconfigurable Robots Mobile Chain Lattice
Lattice Self-Reconfiguration Telecube G1
Proteo Proteo (never built) Rhombic Face (Edge length = 5 cm)
I-Cube, Cem Unsal @ CMU Metamorphic, Chirikjian @ Hopkins
Molecule: Kotay & Rus Crystal: Vona & Rus Dartmouth
Satoshi Murata (lattice) • Fracta • 3D fracta
Molecube, Lipson @ cornell ATRON, Ostergaard, et. al @ U. S. Denmark
Inoue, Pnumatic Riken, Vertical
Stochastic/Graph Grammars • No main actuation (external) • Klavins • Lipson • Latching • Magnets • Pressure differential in oil
Chain Self-ReconfigurationPolyBot Generation 2 (G2), and 3 (G3)
Polypod UPenn superbot
Conro, Shen/will @ ISI Mtran, Murata et al
1 DOF motion docking Local self-collision detection Higher stiffness dock No singularities, No mechanical advantage Discrete motions GeneralManipulation difficult Unstructured environments difficult 6 DOF motion docking Global self-collision detection Lower stiffness dock Singularities Complicates control Arbitrary motions Lattice vs Chain Lattice is easier for self-reconfiguration Chain is easier for locomotion/manipulation
Main drives: • Geared DC motors (most popular) • Magnetic • Pneumatic • None Not shown yet: • Combustive: easier if modules are large • Thermal (nuclear?): perhaps in space • Mechanochemical: does this exist? • Electrostatic: ok if small? High voltages • Molecular motors: if very tiny
Latching mechanisms • Magnetic – issue: strength • Mechanical – issue: actuator (size (strength/speed)) • Pneumatic – issue: valves, supply • Hydraulic – issue: valves, supply Not shown yet: • Electrostatic: ok if small? High voltages • Dry Adhesive: attach/detach motion?
Stolen from: Esbed Ostergaard Thesis U. Southern Denmark
Questions • What are the important parameters for the motion part? What are the tradeoffs? • DOF? • Shape? • #of attachments • Workspace? • What are the important parameters for attaching/detaching mechanisms?
What on earth are we going to do with these robots? • NASA program • It’s going to be more robust to send specialized machine per task • Multifunction cost savings vs capability • Space station repair • Mars exploration • Moon station (selfreplication) • Construction • Locomotion with manipulation • E.g. mine sensor support w/shoring • Building construction • Architecture • Exploration • Search and rescue • Undersea mining • Planetary mining • Shape only • Structures • Telepario • Shady robots • Programmable antennae • Research contribution for itself • On microscale • Self assembling chips (self-walking chips?) • Mechanical RSA (tiles form shapes to open locks) • Mechanical FPGA
Shape vs function • 3 people do shape only • Fundamental assumptions(?) • Self • Organizing • Reconfiguring • Repairing • Funding • Communities to relate to? • Complexity systems community • Nanoscience community (foundations of nanoscience) • Availability of low cost reliable hardware helps to enable robotics research • Common platform, (e.g. mote like) • Sources of funding? • DARPA, NSF, Europe, (Brad has money) • Japan Aist/TiTech last