Self-position estimation apparatus

A self-position estimation apparatus comprising:

• an image capturing unit capturing a plurality of driving images in a state where an own vehicle is driven along a predetermined driving route and a plurality of reference images at a plurality of positions along the predetermined driving route;
• a detection unit detecting feature points on each of the plurality of driving images and feature points on each of the plurality of reference images correlated to each of the reference images;
• a storage unit storing map information which includes the feature points on each of the plurality of reference images and a position and a posture of the image capturing unit at a time each of the plurality of reference images is captured by the image capturing unit;
• an estimation unit selecting a similar image similar to one of the plurality of driving images from the plurality of reference images to correlate the feature points on the one of the plurality of driving images and feature points on the similar image, the estimation unit estimating a position and a posture of the own vehicle on the predetermined driving route based on a correlation result, the feature points on each of the reference images detected by the detection unit serve as environment feature points in an environment along the predetermined driving route;
• and
• a setting unit estimating a road surface gradient difference of the predetermined driving route and setting a detection range (As) of correlation feature points on each of the plurality of driving images correlated to the environment feature points based on the estimated road surface gradient difference, the setting unit selecting the similar image similar to one of the plurality of driving images from the plurality of reference images based on the correlation feature points detected at the detection range,
• wherein the image capturing unit is fixed to a predetermined position of the own vehicle to capture an image of a predetermined region ahead of the image capturing unit,
• the setting unit selects from the plurality of reference images the similar image which is the most similar to the predetermined region ahead of the image capturing unit and estimates the road surface gradient difference from a difference between a road surface gradient based on the position and the posture of the image capturing unit correlated to the selected similar image and a road surface gradient based on the position and the posture of the image capturing unit estimated on the driving image which is previously captured, and
• the detection range is limited to only a portion of an entirety of the image of the predetermined region.