Driving assistance device

1. A driving assistance device configured to be mounted on an own vehicle, the driving assistance device comprising:

a lane change detection unit that detects that the own vehicle is scheduled to perform a lane change;

a lane identification unit configured to identify an original lane and a destination lane based on detection of a first boundary and a second boundary, the original lane being a lane in which the own vehicle travels before the lane change is performed, the destination lane being a lane in which the own vehicle is scheduled to travel after the lane change is performed, the first boundary being a boundary between the original lane and the destination lane, the second boundary being a boundary that defines the original lane and is located on a side opposite to the first boundary;

a first space determination unit that configured to determine that a passable space is present at least between the own vehicle and an object vehicle traveling in the destination lane, on the side of the own vehicle nearer the destination lane with respect to a position of the own vehicle in the original lane, the passable space being a space through which a moving object can pass the own vehicle, the passable space comprising a space between the own vehicle and an object vehicle traveling in the destination lane; and

an operation control unit configured to cause the own vehicle to perform a lateral movement operation before performing a lane change based on the first space determination unit determining that the passable space is present, the lateral movement operation causing the own vehicle to approach the destination lane.

2. The driving assistance device according to claim 1 , further comprising a speed identification unit that identifies a speed of the own vehicle, wherein:

determining that the passable space is present is based on an interval in an intersecting direction intersecting the destination lane between the own vehicle and the object vehicle being a first threshold distance or more; and

the first threshold distance is set to be smaller as the identified speed is lower.

3. The driving assistance device according to claim 1 , further comprising a notification control unit configured to control a notification unit mounted on the own vehicle to cause the notification unit to notify that it has been detected that the own vehicle is scheduled to perform a lane change and it has been determined that the passable space is present.

4. The driving assistance device according to claim 1 , wherein

the operation control unit is configured to determine that an object is present or absent in the passable space, and

the operation control unit causes the own vehicle to perform the lateral movement operation based on determining that no moving object is detected in the passable space, and

operation control unit disables the own vehicle from performing the lateral movement operation based on determining that the moving object is detected in the passable space.

5. The driving assistance device according to claim 1 , wherein as the lateral movement operation, the operation control unit causes the own vehicle to operate so that an interval between the own vehicle and the first boundary in an intersecting direction is shorter than an interval between the own vehicle and the second boundary in the intersecting direction, the intersecting direction being a direction intersecting the destination lane.

6. The driving assistance device according to claim 1 , wherein as the lateral movement operation, the operation control unit causes the own vehicle to operate so that an interval between the own vehicle and the first boundary in an intersecting direction is shorter than an interval between the own vehicle and an object that is present on a side of the second boundary when viewed from the own vehicle, the intersecting direction being a direction intersecting the destination lane.

7. The driving assistance device according to claim 1 , wherein as the lateral movement operation, the operation control unit causes the own vehicle to operate so that an interval between the own vehicle and the first boundary in an intersecting direction intersecting the destination lane becomes a predetermined distance, the predetermined distance being smaller than ½ of a width of the original lane.

8. The driving assistance device according to claim 1 , wherein as the lateral movement operation, the operation control unit causes the own vehicle to operate so that an interval between the own vehicle and the object vehicle in an intersecting direction intersecting the destination lane is shorter than an interval between the own vehicle and the second boundary in the intersecting direction.

9. The driving assistance device according to claim 1 , wherein:

the first space determination unit determines that the passable space is present based on an interval between the own vehicle and the object vehicle in an intersecting direction intersecting the destination lane being equal to or greater than a first threshold distance; and

as the lateral movement operation, the operation control unit causes the own vehicle to operate so that the interval between the own vehicle and the object vehicle in the intersecting direction intersecting the destination lane becomes a predetermined distance, the predetermined distance being shorter than the first threshold distance.

10. The driving assistance device according to claim 1 , wherein:

as the lateral movement operation, the operation control unit causes the own vehicle to travel parallel to the first boundary at a predetermined distance away from the first boundary in the original lane; and

for a state in which the object vehicle is not present in the destination lane, the predetermined distance is set to be shorter than for a state in which the object vehicle is present in the destination lane.

11. The driving assistance device according to claim 1 , further comprising a second space determination unit configured to determine that a movement candidate space of a predetermined size or more is present on a side of the destination lane when viewed from the own vehicle, wherein

for a state in which it is detected that the own vehicle is scheduled to perform a lane change, it is determined that the passable space is present, and it is determined that the movement candidate space is present, the operation control unit causes the own vehicle to perform the lateral movement operation, and

for a state in which it is detected that the own vehicle is scheduled to perform a lane change, it is determined that the passable space is present, and it is determined that the movement candidate space is not present, the operation control unit disables the own vehicle from performing the lateral movement operation.

12. The driving assistance device according to claim 1 , wherein:

the operation control unit determines that a preceding vehicle is present in a range of a predetermined distance or less in front of the own vehicle in the original lane; and

for a state in which it is determined that the preceding vehicle is present in the range, as the lateral movement operation, the operation control unit causes the own vehicle to operate so that a front side of the own vehicle is closer to the destination lane than a rear side of the own vehicle is.