Variable-resolution velocity-time roadmap generation considering safety constraints for autonomous vehicles

This research develops a new roadmap method for autonomous vehicles based on variable-resolution partitioning of a continuous state-time space. Unlike conventional roadmaps, which include position information only, the proposed roadmap also includes velocity and time information. Each node of the proposed roadmap contains position and velocity information and is the same as a Variable-resolution Velocity Roadmap (VVR). Each directed link of the proposed roadmap has a range of time values, where the time ranges are determined by variable-resolution partitioning of the time space. An ordered pair of nodes is connected by a directed link within a time region if any combination of their velocity and time values is within the acceptable range of the nodes and produces a trajectory satisfying a set of safety constraints. In this manner, a possible trajectory, with transit time, connecting an arbitrary starting node and destination node is obtained by applying a graph search technique on the proposed roadmap. The proposed method is demonstrated through simulations.