Customizing PRM Roadmaps at Query Time

In this paper, we propose a new approach for building and querying probabilistic roadmaps. In the roadmap construction stage, we build coarse roadmaps by performing only an approximate validation of the roadmap nodes and/or edges. In the query stage, the roadmap is validated and re ned only in the area of interest for the query, and moreover, is customized in accordance with any speci ed query preferences. This approach, which postpones some of the validation checks (e.g., collision checks) to the query phase, yields more eÆcient solutions to many problems. An important bene t of our approach is that it gives one the ability to customize the same roadmap in accordance with multiple, variable, query preferences. For example, our approach enables one to nd a path which maintains a particular clearance, or makes at most some speci ed number of sharp turns. Our preliminary results on problems drawn from diverse application domains show that this new approach dramatically improves performance, and shows remarkable exibility when adapting to di erent query requirements. This research supported in part by NSF CAREER Award CCR-9624315 (with REU Supplement), NSF Grants IIS-9619850 (with REU Supplement), ACI-9872126, EIA-9975018, EIA-9805823, and EIA-9810937, and by the Texas Higher Education Coordinating Board under grant ARP-036327-017.