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

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

Assembly Planning Example

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

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

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:

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

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

OR Gate for uiujuk

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

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