Driving assistance device for vehicle and driving assistance method for vehicle

1. A driving assistance device for a vehicle, comprising:

an obstacle detection unit that detects an obstacle in a periphery of the vehicle using a sensing result of a peripheral monitoring sensor for monitoring the periphery of the vehicle;

an avoidance determination unit that sequentially determines whether an avoidance of the obstacle detected by the obstacle detection unit is necessary, according to a route of the vehicle; and

a warning processing unit that controls a warning device to issue a warning when the avoidance determination unit determines that the avoidance of the obstacle is necessary, wherein:

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, the warning processing unit controls the warning device to continue issuing the warning when an obstacle distance, which is a distance of the obstacle to the vehicle, is less than a predetermined threshold value set in advance.

2. The driving assistance device for the vehicle according to claim 1 , wherein:

the predetermined threshold value is set in a plurality of stages with different threshold distances; and

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, and the obstacle distance is less than the predetermined threshold value, the warning processing unit changes a mode of the warning based on which one of the threshold distances set in the plurality of stages the obstacle distance is less than.

3. The driving assistance device for the vehicle according to claim 2 , wherein:

the warning processing unit controls a plurality of types of the warning device;

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, and the obstacle distance is less than one of the threshold distances set to be a shorter threshold distance, the warning processing unit increases a numerical number of types of the warning device for issuing the warning; and

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, and the obstacle distance is equal to or larger than one of the threshold distances set to be a longer threshold distance, the warning processing unit decreases the numerical number of types of the warning device for issuing the warning.

4. The driving assistance device for the vehicle according to claim 3 , wherein:

the warning processing unit controls the plurality of types of the warning device, which includes at least a warning element for issuing the warning by a display, to issue the warning; and

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, the obstacle distance is less than the one of the threshold distances, and the warning processing unit decreases the numerical number of types of the warning device for issuing the warning to be one type based on which one of the threshold distances set in the plurality of stages the obstacle distance is less than, the warning processing unit controls one type of the warning device to issue the warning by the display.

5. The driving assistance device for the vehicle according to claim 2 , wherein:

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, and the obstacle distance is equal to or larger than one of the threshold distances set to be a longest threshold distance among the threshold distances set in the plurality of stages, the warning processing unit controls the warning device to terminate the warning.

6. The driving assistance device for the vehicle according to claim 1 , wherein:

in a case where the avoidance determination unit determines that the avoidance of the obstacle is unnecessary after starting the warning, and the obstacle distance is less than the predetermined threshold value, the warning processing unit changes a mode of the warning from a mode before the avoidance determination unit determines that the avoidance of the obstacle is unnecessary while the warning processing unit controls the warning device to continue issuing the warning.

7. The driving assistance device for the vehicle according to claim 1 , further comprising:

one or more processors; and

a memory coupled to the one or more processors and storing program instructions that when executed by the one or more processors cause the one or more processors to provide at least: the obstacle detection unit; the avoidance determination unit; and the warning processing unit.

8. A driving assistance method for a vehicle comprising:

detecting an obstacle in a periphery of the vehicle using a sensing result of a peripheral monitoring sensor for monitoring the periphery of the vehicle;

sequentially determines whether an avoidance of the obstacle detected is necessary, according to a route of the vehicle;

controlling a warning device to issue a warning when determining that the avoidance of the obstacle is necessary; and

in a case where determining that the avoidance of the obstacle is unnecessary after starting the warning, controlling the warning device to continue issuing the warning when an obstacle distance, which is a distance of the obstacle to the vehicle, is less than a predetermined threshold value set in advance.