Segment determination device and segment determination method

A segment determination device comprising:

• at least one memory configured to store a program;
• and
• a central processing unit (CPU) coupled to the at least one memory and configured to execute the program to:
• acquire altitude information about a plurality of points on a road on which the vehicle travels;
• determine a feature amount that indicates gradient information about the road based on the altitude information about points including a first point ahead of the vehicle in a traveling direction of the vehicle and a second point further ahead of the first point among the plurality of points, wherein the feature amount is determined as a sum of areas of regions surrounded by a first line and a second line, the first line obtained by connecting the first point ahead of the vehicle and the second point farther from the vehicle than the first point among the plurality of points, and the second line obtained by sequentially connecting a plurality of points from the first point to the second point among the plurality of points;
• and
• in a case where the feature amount is outside of a predetermined range, determine a segment as a constant gradient segment, in which the first point is set as a start point and whichever of two points adjacent to the second point that is closer to the vehicle is set as an end point,
• wherein the constant gradient segment is a gradient that is constant and a vehicle sets a constant gear stage of a transmission of the vehicle while traveling over the constant gradient segment.