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Assembly Planning

Assembly Planning. Levels of Problems. Parts are assumed free-flying  Assembly sequence planning Tools/fixtures are taken into account Entire manipulation system is taken into account  M anipulation planning. Applications. Answers to questions such as:

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Assembly Planning

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  1. Assembly Planning

  2. 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

  3. 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 process be parallelized? • Design for manufacturing and servicing • Design of manufacturing systems

  4. Assembly Sequence Planning • Very constrained goal state, but unconstrained initial state Disassembly planning • Large number of dofs, but simple paths Motion space

  5. Set of Assembly Sequences as an AND/OR Graph

  6. Contact Analysis How would you compute a directionof motion for the T-shaped object?

  7. Contact Analysis

  8. Planning Approaches • Generate-and-test • Generate-and-test plus caching • Non-directional blocking graph • Interference diagram

  9. 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.

  10. 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.

  11. Directional Blocking Graph(for infinitesimal translations)

  12. Directional Blocking Graph(for infinitesimal translations) How do you see that this is a potentially good direction?

  13. Directional Blocking Graph(for infinitesimal translations) How do you see that this is a potentially good direction?

  14. Motion Space(for infinitesimal translations) The motion space is the spaceof all directions of motionIt does not say which objects are moving S1

  15. Non-Directional Blocking Graph(for infinitesimal translations) The NDBG is a partition of a motion space into cells (points and arcs) What happens when one switches from one cell to the next?

  16. Non-Directional Blocking Graph(for infinitesimal translations)  Assembly sequencing in polynomial time

  17. Non-Directional Blocking Graph(for extended translations) How would you compute the NDBG?

  18. Sketch of an Assembly Planner • Plan a sequence that is valid for extended translations • If one is found, return it • Else plan a sequence that is valid for infinitesimal translations • If none is found then return failure • Else use a general motion planner to validate each step of the sequence

  19. Extension to 3-D(for infinitesimal or extended translations) What is the motion space?

  20. Extension to 3-D(for infinitesimal or extended translations) How would you do for extended translations?

  21. More Extensions • What would be the motion space if we allowed parts to both translate and rotate? • What about multi-step motions, e.g., along d1 for distance l1, then d2 for distance l2, ...?

  22. Contact Analysis

  23. More Extensions • What would be the motion space if we allowed parts to both translate and rotate? • What about multi-step motions, e.g., along d1 for distance l1, then d2 for distance l2, ...?

  24. Interference Diagram

  25. Interference Diagram

  26. Assembly Sequences Generated Using NDBGs Sandia National Labs (R. Wilson) Munich University (F. Schwarzer)

  27. Number of Hands An assembly that requires n hands

  28. Mononoticity of an Assembly

  29. Mononoticity of an Assembly

  30. With translations only monotone two-handed Example Assemblies • With translations only • non-monotone, 2-handed • monotone, 3-handed • With general motions • monotone, 2-handed

  31. With translations only monotone two-handed Example Assemblies • With translations only • non-monotone, 2-handed • monotone, 3-handed • With general motions • monotone, 2-handed

  32. Nonlinearalizable 1-Handed Assembly

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