Efficient Cost Computation in Cost Map Planning for Non-Circular Robots

Abstract

For a robot with a circular footprint, obstacles in a map can be inflated by the radius of the footprint, and planning can treat the robot as a point robot. Many robotic vehicles however have non-circular footprints. When operating in cluttered spaces it therefore becomes important to evaluate the footprint of these robots against a cost map. This evaluation is one of the major computational burdens in planning for robots whose footprints can not be assumed to be circular. In this paper, we propose an efficient method for evaluating a footprint of the robot against a cost map. Our method involves a transformation of the set of points covered by the footprint of the robot into two sets of points: points that should be evaluated against the cost map with inflated obstacles, and ppints that should be evaluated against the original cost map. The cumulative number of these points is much smaller than the number of points in the original footprint of the robot. Moreover, the method automatically reduces the robot to a single point when its footprint is circular. On the theoretical side, the paper proves the correctness of our method. On the experimental side, the paper shows that the method results in a significant speedup.