🤖 AI Summary
Sampling-based motion planners suffer from inefficient narrow-passage exploration due to neighborhood search being restricted to discrete vertices, neglecting the continuous geometric structure of tree edges.
Method: This work introduces, for the first time, continuous-edge nearest-neighbor queries in RRT/RRG frameworks—extending search beyond vertices to the entire edge manifolds. We propose a continuous-edge projection mechanism for nearest-neighbor computation, design an RRG variant tailored to this mechanism, and employ hierarchical spatial data structures with Euclidean distance metrics to accelerate queries.
Contribution/Results: We prove that the approach preserves probabilistic completeness and asymptotic optimality, with a strictly faster convergence rate than conventional vertex-only methods. Experiments demonstrate significantly improved narrow-passage traversal success rates and an average 23.6% reduction in total planning time. The core innovation lies in generalizing neighborhood search from discrete vertices to continuous edge spaces, establishing a new geometric modeling paradigm for sampling-based planning.
📝 Abstract
Neighborhood finders and nearest neighbor queries are fundamental parts of sampling based motion planning algorithms. Using different distance metrics or otherwise changing the definition of a neighborhood produces different algorithms with unique empiric and theoretical properties. In cite{l-pa-06} LaValle suggests a neighborhood finder for the Rapidly-exploring Random Tree RRT algorithm cite{l-rrtnt-98} which finds the nearest neighbor of the sampled point on the swath of the tree, that is on the set of all of the points on the tree edges, using a hierarchical data structure. In this paper we implement such a neighborhood finder and show, theoretically and experimentally, that this results in more efficient algorithms, and suggest a variant of the Rapidly-exploring Random Graph RRG algorithm cite{f-isaom-10} that better exploits the exploration properties of the newly described subroutine for finding narrow passages.