BACKGROUND

Field

The present disclosure relates to an autonomous driving system mounted on a vehicle.

Background Art

DE 102012025328A1 discloses a device that determines whether or not to execute lane change based on vehicle speeds of and inter-vehicle distances of vehicles traveling in an adjacent lane when determining that a driver has an intention to perform lane change.

SUMMARY

For realizing smooth traffic, it is demanded not to generate an imbalance in a traffic flow in each of lanes.

However, according to the prior art described in DE 102012025328A1, lane change is performed regardless of an imbalance in a traffic flow when lane change is demanded. Therefore, an imbalance in a traffic flow cannot be eliminated by using this prior art.

The present disclosure is made in the light of the problem as described above, and has an object to provide an autonomous driving system that can contribute to eliminate an imbalance in a traffic flow in each of lanes of a road on which an own vehicle is traveling.

An autonomous driving system according to the present disclosure includes at least an information acquisition section, a lane selection section and a control section. The information acquisition section is configured to acquire information concerning a vehicle density in an adjacent lane that is adjacent to a lane on which an own vehicle is traveling, when the own vehicle travels on a road having a plurality of lanes. The lane selection section is configured to select the adjacent lane as an own vehicle travel lane, when the vehicle density in the adjacent lane that is calculated from the information acquired by the information acquisition section is lower than a threshold density that is determined in accordance with relations between the own vehicle and surrounding vehicles. The control section is configured to perform lane change to the adjacent lane autonomously, or propose lane change to the adjacent lane to a driver, when the lane selection section selects the adjacent lane as the own vehicle travel lane.

According to the above described configuration, when the vehicle density in the adjacent lane is lower than the threshold density, lane change to the adjacent lane is performed autonomously, or lane change to the adjacent lane is proposed to a driver. Therefore, a traffic flow is dispersed by the lane change of the own vehicle at least between the lane on which the own vehicle is traveling and the adjacent lane. Consequently, according to the autonomous driving system according to the present disclosure, contribution can be made to elimination of an imbalance in a traffic flow in each of lanes.

The lane selection section may be configured to determine the threshold density in accordance with at least a relative speed to the own vehicle of a vehicle traveling in the adjacent lane. According to this configuration, whether to perform lane change to the adjacent lane is determined with a flow state in the adjacent lane also taken into consideration, in addition to the vehicle density in the adjacent lane. Consequently, an effect of lane change of the own vehicle dispersing a traffic flow can be enhanced, and lane change to suit to a sense of an occupant can be realized. In this case, the threshold density may be set at a smaller value as the relative speed is low.

The lane selection section may be configured to determine the threshold density in accordance with at least a forward inter-vehicle distance between the own vehicle and a vehicle traveling ahead of the own vehicle in the lane on which the own vehicle is traveling, or a rearward inter-vehicle distance between the own vehicle and a vehicle traveling behind the own vehicle in the lane on which the own vehicle is traveling. According to this configuration, whether to perform lane change to the adjacent lane is determined with a congestion state in the lane on which the own vehicle is traveling also taken into consideration, in addition to the vehicle density in the adjacent lane. Consequently, an effect of lane change of the own vehicle dispersing a traffic flow can be enhanced, and lane change to suit to a sense of an occupant can be realized. In this case, the threshold density may be set at a smaller value as the forward inter-vehicle distance or the rearward inter-vehicle distance is long.

The lane selection section may be configured to determine the threshold density in accordance with at least a vehicle density in a lane on which the own vehicle is traveling. According to this configuration, whether to perform lane change to the adjacent lane is determined with a congestion state in the lane on which the own vehicle is traveling also taken into consideration, in addition to the vehicle density in the adjacent lane. Consequently, an effect of lane change of the own vehicle dispersing a traffic flow can be enhanced, and lane change to suit to a sense of an occupant can be realized. In this case, the threshold density may be set at a smaller value as a vehicle density in the lane on which the own vehicle is traveling is small.

Further, the lane selection section may be configured to select as the own vehicle travel lane a lane having a lower vehicle density, of both adjacent lanes that are adjacent to a lane on which the own vehicle is traveling, when vehicle densities in both the adjacent lanes are lower than the threshold density. According to this configuration, contribution can be made to elimination of an imbalance in a traffic flow in each of lanes in a road having three or more lanes.

The lane selection section may be configured to select as the own vehicle travel lane a lane satisfying a constraint determined by regulation information or traveling road information, of both adjacent lanes that are adjacent to a lane on which the own vehicle is traveling, when vehicle densities in both the adjacent lanes are lower than the threshold density. According to this configuration, while satisfying the constraint determined by the regulation information or the traveling road information, contribution can be made to elimination of an imbalance in a traffic flow in each of lanes in a road having three or more lanes.

The lane selection section may be configured to select as the own vehicle travel lane a lane that can make a traveling state of the own vehicle approach more loosely a target traveling state, of both adjacent lanes that are adjacent to a lane on which an own vehicle is traveling, when vehicle densities in both the adjacent lanes are lower than the threshold density. According to this configuration, while making the traveling state of the own vehicle approach the target traveling state, contribution can be made to elimination of an imbalance in a traffic flow in each of lanes in a road having three or more lanes.

According to the autonomous driving system according to the present disclosure, when the vehicle density in the adjacent lane is lower than the threshold density, lane change to the adjacent lane is performed autonomously, or lane change to the adjacent lane is proposed to a driver. Therefore, a traffic flow is dispersed by the lane change of the own vehicle at least between the lane on which the own vehicle is traveling and the adjacent lane. Consequently, according to the autonomous driving system according to the present disclosure, contribution can be made to elimination of an imbalance in a traffic flow in each of lanes.

