Reconfiguration Mechanism Design

1
Reconfiguration Mechanism Design

• Mark Yim
• Associate Professor and
• Gabel Family Associate Professor
• Dept. of Mechanical Engineering and Applied
  Mechanics,
• University of Pennsylvania

2

• 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.

3
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 -gt 65,000 cm3
• Assume density of water (1kg 1000 cm3 )
• 65,000,000 modules
• 1000 modules per cm3
• Cost 1,007,502.025

4
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

5
Outline

• Review of Motion mechanisms
• Chain style reconfiguration
• Lattice style reconfiguration
• Review of Latching mechanisms
• Discussion

6
Three Classes of Existing Self-Reconfigurable
Robots
Mobile
Chain
Lattice
7
Telecube G1
Lattice Self-Reconfiguration
8
Proteo (never built)
Proteo
Rhombic Face (Edge length 5 cm)
9

• I-Cube, Cem Unsal _at_ CMU

• Metamorphic, Chirikjian _at_ Hopkins

10
Dartmouth

• Molecule Kotay Rus
• Crystal Vona Rus

11
Satoshi Murata (lattice)

• Fracta
• 3D fracta

12

• Molecube, Lipson _at_ cornell

• ATRON, Ostergaard, et. al _at_ U. S. Denmark

13
Inoue, Pnumatic
Riken, Vertical
14
Stochastic/Graph Grammars

• No main actuation (external)
• Klavins
• Lipson
• Latching
• Magnets
• Pressure differential in oil

15
Chain Self-ReconfigurationPolyBot Generation 2
(G2), and 3 (G3)
16

• Polypod

• UPenn superbot

17

• Conro, Shen/will _at_ ISI

• Mtran, Murata et al

18
Nilsson, Dragon
19
Lattice vs Chain

• 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 is easier for self-reconfiguration Chain
is easier for locomotion/manipulation
20
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

21
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?

22
Stolen from Esbed Ostergaard Thesis U. Southern
Denmark
23
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?

24
(No Transcript)
25
What on earth are we going to do with these
robots?

• NASA program
• Its 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

26

• 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