Assembly Planning

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Assembly Planning
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Levels of Problems

• Parts are assumed free-flying ?Assembly sequence
  planning
• Tools/fixtures are taken intoaccount
• Entire manipulation system is taken into
  account ? Manipulation planning

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Applications

• Answers to questions such as
• How many parts need to be removed to extract a
  given part P?
• Can the product be assembled by adding a single
  part at a time?
• How much can the assembly processed by
  parallelized?
• Design for manufacturing and servicing
• Design of manufacturing systems

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Assembly Sequence Planning

• Very constrained goal state, but unconstrained
  initial state ? Disassembly planning
• Large number of dofs, but simple paths? Motion
  space

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Set of Assembly Sequences as an AND/OR Graph
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Contact Analysis
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Contact Analysis
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Number of Hands
An assembly that requires n hands
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Mononoticity of an Assembly
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Mononoticity of an Assembly
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Example Assemblies

• With translations only
• monotone
• two-handed

• With translations only
• non-monotone, 2-handed
• monotone, 3-handed
• With general motions
• monotone, 2-handed

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Example Assemblies

• With translations only
• monotone
• two-handed

• With translations only
• non-monotone, 2-handed
• monotone, 3-handed
• With general motions
• monotone, 2-handed

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Nonlinearalizable 1-Handed Assembly
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Planning Approaches

• Generate-and-test
• Generate-and-test plus caching
• Non-directional blocking graph
• Interference diagram

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Directional Blocking Graph(for infinitesimal
translations)
R.H. Wilson and J.C. Latombe. Geometric Reasoning
about Mechanical Assembly. Artificial
Intelligence, 71(2)371-396, 1995.
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Directional Blocking Graph(for infinitesimal
translations)
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Non-Directional Blocking Graph(for infinitesimal
translations)
The NDBG is a partition of a motion space into
cells
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Non-Directional Blocking Graph(for infinitesimal
translations)
? Assembly sequencing in polynomial time
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Non-Directional Blocking Graph(for extended
translations)
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Extension to 3-D
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Extension to 3-D
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Interference Diagram
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Interference Diagram
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Assembly Sequences Generated Using NDBGs
Sandia National Labs (R. Wilson)
Munich University (F. Schwarzer)