Gradient information calculating system, vehicle running control system, navigation system, and gradient information calculating method

Abstract

A gradient information calculating system includes a first calculating unit () that detects three-dimensional location information through autonomous navigation, and calculates a first gradient value (θb, B), based on a distance (m) traveled, and an on-plane distance (L) obtained by projecting the distance (m) traveled on a horizontal plane, a road map information storing unit () that stores road map information that represents each road by nodes of which the location information is known, and a link that connects the nodes, a second calculating unit () that estimates elevations of the nodes from previously measured elevation data, and calculates a second gradient value (A), based on a difference in elevation between the nodes and the length of the link, and a gradient data selecting unit () that selects one of the first and second gradient values to be adopted as a gradient value of the link, according to a difference between the first and the second gradient values.