1. Criticality-Based Motion Planning (2)
CS 326A: Motion Planning
Criticality-Based Motion Planning (2)

2. Topics Target finding  Information (or belief) state/space
Part orientation  Sensorless reduction of uncertainty
Assembly planning  Path space
Stereotaxic radiosurgery

3. Assembly Planning Example

4. Levels of Problems
Parts are assumed free-flying Assembly sequence planning
Tools/fixtures are taken into account
Entire manipulation system is taken into account  Manipulation planning

5. Assembly Sequence Planning
Example of a multi-robot coordination problem, but …
Very constrained goal state, but unconstrained initial state  Disassembly planning
Many dofs, but simple paths  Motion space

6. Various “Interesting” Cases
Multi-hand:
Non-monotonic 2-handed assembly:
An assembly on n parts may require up to n hands for its (dis-)assembly [Natarajan]
No single part can be added or removed:

7. Various “Interesting” Cases
With translations only
non-monotone, 2-handed
monotone, 3-handed
With general motions
monotone, 2-handed
With translations only
monotone
two-handed

8. Complexity of Partitioning
Assembly partitioning problem: - Given a set of non-overlapping polygons, - Decide if a proper subset of them can be removed as a rigid body without colliding with the other polygons.
This problem is NP-complete

10. OR Gate for uiujuk

11. Planning Approaches
Generate-and-test: Hypothesize a subassembly and test if it can separated from the rest using contact analysis …
But … exponential number of subassemblies:
O(2n) subassemblies,
but only two pairs can
be separated

12. Planning Approaches Generate-and-test Generate-and-test plus caching
Non-directional blocking graph (limited to single-step motions)
Interference diagram