Self-localization estimation device

1. A self-localization estimation device comprising:

a processor;

a non-transitory computer-readable storage medium; and

a set of computer-executable instructions stored on the non-transitory computer-readable storage medium that cause the processor to:

acquire map information including lane information specifying lanes in which vehicles are enabled to travel;

detect in-lane localization information specifying an in-lane position of an own vehicle, the in-lane position being a position of the own vehicle in a lane in which the own vehicle is travelling;

estimate absolute-localization information specifying an absolute localization of the own vehicle and an error in the absolute localization;

determine whether there is lane-relevant candidate information, based on a degree of overlap between the in-lane position including a first error distribution thereof and the absolute localization including a second error distribution thereof, the lane-relevant candidate information representing which lanes identified by the lane information that the in-lane position of the own vehicle corresponds to; and

estimate, based on a result of the determination of whether there is lane-relevant candidate information, a position of the own vehicle with respect to the lane information included in the map information.

2. The self-localization estimation device according to claim 1 , wherein:

the set of computer-executable instructions further cause the processor to:

continue, upon determining that there are two items of the lane-relevant candidate information, estimation of the localization of the own vehicle until at least one of the items of the lane-relevant candidate information satisfies a screening condition; and

perform a screening of the items of the lane-relevant candidate information upon at least one of the items of the lane-relevant candidate information satisfies the screening condition.

3. The self-localization estimation device according to claim 2 , wherein the set of computer-executable instructions further cause the processor to:

detect comparison-target information different from information to be used in the detection of the in-lane localization information and the estimation of the absolute-localization information;

determine whether at least one of the items of the lane-relevant candidate information satisfies the screening in accordance with the comparison-target information; and

perform screening of the items of the lane-relevant candidate information in accordance with a result of the determination of whether at least one of the items of the lane-relevant candidate information satisfies the screening.

4. The self-localization estimation device according to claim 3 , wherein the set of computer-executable instructions further cause the processor to:

detect, as the comparison-target information for each item of the lane-relevant candidate information, line-pattern information that is detected from an image taken by an imaging device installed in the own vehicle, the line-pattern information being a travelling line-pattern information specifying a line pattern of at least one lane boundary line that marks the lane in which the own vehicle is travelling;

detect, from the lane information, a map line-pattern information for specifying a line pattern of at least one lane boundary line included in the lane information;

determine whether the travelling line-pattern information for each item of the lane-relevant candidate information mismatches the map line-pattern information; and

reject one of the items of the lane-relevant candidate information upon the travelling line-pattern information for the one of the items of the lane-relevant candidate information mismatching the map line-pattern information.

5. The self-localization estimation device according to claim 4 , wherein the set of computer-executable instructions further cause the processor to:

estimate the absolute-localization information based on a detection result by a gyro sensor;

detect the comparison-target information based on navigation signals received from a plurality of navigation satellites; and

determine that the screening condition is satisfied for one item of the lane-relevant candidate information upon determining that a position of the own vehicle specified based on the comparison-target information and the one item of the lane-relevant candidate information deviate from each other, thus rejecting the deviated one item of the lane-relevant candidate information.

6. The self-localization estimation device according to claim 3 , wherein the set of computer-executable instructions further cause the processor to:

when there are items of the lane-relevant candidate information, and when at least one item of the lane-relevant candidate information deviates from the lane information, determine that the screening condition is satisfied for the at least one item of the lane-relevant candidate information, thus rejecting the deviated at least one item of the lane-relevant candidate information.

7. The self-localization estimation device according to claim 1 , wherein the set of computer-executable instructions further cause the processor to

notify a user that a confidence level of a result is low when plural items of the lane-relevant candidate information are present or when an amount of the error of the absolute localization is equal to or more than a predetermined margin.