Patent ID: 7693613

Claim:
A method for estimating, by a terrain navigational system of a moving vehicle with limited maneuverability, curvilinear distances to be traversed by the vehicle from its instantaneous position to reach points of a travel region containing potential obstacles to be circumvented by said vehicle in order to establish a distance map covering the travel region wherein the curvilinear distance estimations of the distance map are obtained by means of a distance transform, the method comprising the steps of: providing a virtual, impassible obstacle in addition to detected real impassible obstacles; arranging the virtual, impassible obstacle in a predetermined spatial position with respect to the vehicle; moving the virtual, impassible obstacle in a predetermined relationship respect to the vehicle; cataloging distance map cells which are associated with the virtual, impassible obstacle that are inaccessible to the vehicle owing to its maneuverability limits; forcing the distance transform to put aside, in its search for the lengths of the shortest paths, the paths that are out of range of the vehicle owing to its limited maneuverability; and plotting a course which prohibits unrealistic vehicle turns based on the paths that are out of range of the vehicle owing to its limited maneuverability.