CS 326 A: Motion Planning Collision Detection and Distance Computation

C-Space Sampling  Need for efficient collision-checking algorithms

Collision Checking vs. Distance Computation Distance is in the workspace between the two closest points distance = 0  collision

It may be easier to check collision than to compute distance

Pure collision checking does not allow us to rigorously test segments C-space

Pure collision checking does not allow us to rigorously test segments C-space

Articulated Robot

High-Level Algorithm 1.Set d to  2.For every pair (L,O) of robot link and workspace obstacle do a.Compute the distance  between L and O b.If  = 0 then return collision c.If  < d then reset d to  3.Return d

Basic problem Given two objects A and B: - either compute the distance between them - or determine whether they collide, or not

Two Approaches  Hierarchical bounding approximation of objects (different types of primitive volumes)  Tracking of closest features

Two Approaches  Hierarchical bounding approximation of objects  Tracking of closest features