Collision prevention apparatus

1 . A collision prevention apparatus, comprising:

a first sensor configured to detect a distance between a leading vehicle in front of an own vehicle and the own vehicle; and

a processor configured to:

based on the detected distance, calculate a relative speed of the own vehicle with respect to the leading vehicle;

determine whether there is a possibility of the own vehicle colliding with the leading vehicle based on the detected distance and the calculated relative speed;

determine whether the leading vehicle that has been temporarily stopped has started moving;

based on determining that the leading vehicle has started moving, increase a target value of an inter-vehicular distance between the own vehicle and the leading vehicle from a standard distance preset for an autonomous deceleration, or increase a target deceleration degree from a standard deceleration degree preset for the autonomous deceleration; and

based on determining that there is the possibility of the own vehicle colliding with the leading vehicle, perform the autonomous deceleration.

2 . The collision prevention apparatus according to claim 1 , wherein the processor is configured to, based on determining that the leading vehicle has started moving, increase the target value of the inter-vehicular distance.

3 . The collision prevention apparatus according to claim 2 , wherein the processor is configured to increase the target value of the inter-vehicular distance as a ratio of the detected distance between the leading vehicle and the own vehicle to the calculated relative speed becomes smaller.

4 . The collision prevention apparatus according to claim 1 , wherein the processor is configured to, based on determining that the leading vehicle has started moving, increase the target deceleration degree for the autonomous deceleration.

5 . The collision prevention apparatus according to claim 4 , wherein the processor is configured to increase the target deceleration degree for the autonomous deceleration as the calculated relative speed becomes higher.

6 . The collision prevention apparatus according to claim 4 , wherein the processor is configured to increase the target deceleration degree for the autonomous deceleration as a difference between (i) the detected distance and (ii) the target value of the inter-vehicular distance, becomes smaller.

7 . The collision prevention apparatus according to claim 1 , wherein

the processor is configured to:

based on determining that the leading vehicle has started moving, increase a first threshold value from a first base value, the first threshold value being used to determine whether to initiate the autonomous deceleration of the own vehicle, and determine whether the detected distance is equal to or smaller than the first threshold value; and

based on determining that the detected distance is equal to or smaller than the first threshold value, perform the autonomous deceleration of the own vehicle.

8 . The collision prevention apparatus according to claim 7 , wherein

the processor is configured to:

based on determining that the leading vehicle has started moving, increase a second threshold value that is greater than the first threshold value from a second base value, the second threshold value being used to determine whether to issue an alarm, and determine whether the detected distance is equal to or smaller than the second threshold value; and

based on determining that the detected distance is equal to or smaller than the second threshold value, issue the alarm by at least one of an alarm lamp, a buzzer, or a vibration of a seat of the own vehicle.

9 . The collision prevention apparatus according to claim 7 , wherein the processor is configured to change the target value to the standard distance and change the target deceleration degree to the standard deceleration degree when an amount of time elapsed from a time point at which it is determined that the detected distance is equal to or smaller than the first threshold value is equal to or greater than a third threshold value.

10 . The collision prevention apparatus according to claim 9 , wherein the processor is configured to set the third threshold value such that the third threshold value is greater as a road intersecting with a road on which the own vehicle is traveling has a greater width and a larger number of lanes than the road on which the own vehicle is traveling.

11 . The collision prevention apparatus according to claim 9 , wherein the processor is configured to set the third threshold value such that the third threshold value is smaller in a case where a road ahead of the own vehicle has a crosswalk or a stop line, compared to a case in which the road ahead of the own vehicle has a crossroads or a T-junction.

12 . The collision prevention apparatus according to claim 9 , wherein the processor is configured to set the third threshold value such that the third threshold value is greater as a congestion degree of vehicles ahead of the own vehicle becomes higher.

13 . The collision prevention apparatus according to claim 7 , wherein the processor is configured to change the target value to the standard distance and change the target deceleration degree to the standard deceleration degree when a traveling distance of the own vehicle from a time point at which it is determined that the detected distance is equal to or smaller than the first threshold value is equal to or greater than a fourth threshold value.

14 . The collision prevention apparatus according to claim 13 , wherein the processor is configured to set the fourth threshold value such that the fourth threshold value is greater as a road intersecting with a road on which the own vehicle is traveling has a greater width and a larger number of lanes than the road on which the own vehicle is traveling.

15 . The collision prevention apparatus according to claim 13 , wherein the processor is configured to set the fourth threshold value such that the fourth threshold value is smaller in a case where a road ahead of the own vehicle has a crosswalk or a stop line, compared to a case in which the road ahead of the own vehicle has a crossroads or a T-junction.

16 . The collision prevention apparatus according to claim 13 , wherein the processor is configured to set the fourth threshold value such that the fourth threshold value is greater as a congestion degree of vehicles ahead of the own vehicle becomes higher.

17 . The collision prevention apparatus according to claim 1 , further comprising a vehicle state sensor including a vehicle speed sensor that detects a vehicle speed of the own vehicle,

wherein the processor is configured to:

based on the detected distance of the first sensor, determine whether there is the leading vehicle that has been temporarily stopped;

determine whether the detected vehicle speed is smaller than a fifth threshold value; and

based on determining that the detected vehicle speed is smaller than the fifth threshold value, and that there is the leading vehicle that has been temporarily stopped, determine whether the leading vehicle that has been temporarily stopped has started moving.

18 . The collision prevention apparatus according to claim 17 , wherein the processor is configured to:

based on determining that the leading vehicle has started moving, increase the target value of the inter-vehicular distance;

increase the target value of the inter-vehicular distance as a ratio of the detected distance to the calculated relative speed becomes smaller;

based on determining that the leading vehicle has started moving, increase the target deceleration degree for the autonomous deceleration;

increase the target deceleration degree for the autonomous deceleration as the calculated relative speed becomes higher;

increase the target deceleration degree for the autonomous deceleration so as to become greater as a difference between (i) the detected distance and (ii) the target value of the inter-vehicular distance becomes smaller;

based on determining that the leading vehicle has started moving, increase a first threshold value;

based on determining that the leading vehicle has started moving, determine whether the detected distance is equal to or smaller than the first threshold value;

based on determining that the detected distance is equal to or smaller than the first threshold value, perform the autonomous deceleration of the own vehicle;

based on determining that the leading vehicle has started moving, increase a second threshold value that is greater than the first threshold value;

based on determining that the leading vehicle has started moving, determine whether the detected distance is equal to or smaller than the second threshold value;

based on determining that the detected distance is equal to or smaller than the second threshold value, issue an alarm by at least one of an alarm lamp, a buzzer, or a vibration of a seat of the own vehicle;

change the target value to the standard distance and change the target deceleration degree to the standard deceleration degree when an amount of time elapsed from a time point at which it is determined that the detected distance is equal to or smaller than the first threshold value is equal to or greater than a third threshold value;

set the third threshold value such that the third threshold value is greater as a road intersecting with a road on which the own vehicle is traveling has a greater width and a larger number of lanes than the road on which the own vehicle is traveling;

set the third threshold value such that the third threshold value is smaller in a case where a road ahead of the own vehicle has a crosswalk or a stop line, compared to a case in which the road ahead of the own vehicle has a crossroads or a T-junction;

set the third threshold value such that the third threshold value is greater as a congestion degree of vehicles ahead of the own vehicle becomes higher;

change the target value to the standard distance and change the target deceleration degree to the standard deceleration degree when a traveling distance of the own vehicle from the time point at which it is determined that the detected distance is equal to or smaller than the first threshold value is equal to or greater than a fourth threshold value;

set the fourth threshold value such that the fourth threshold value is greater as the road intersecting with the road on which the own vehicle is traveling has the greater width and the larger number of lanes than the road on which the own vehicle is traveling;

set the fourth threshold value such that the fourth threshold value is smaller in the case where the road ahead of the own vehicle has the crosswalk or the stop line, compared to the case in which the road ahead of the own vehicle has the crossroads or the T-junction; and

set the fourth threshold value such that the fourth threshold value is greater as the congestion degree of vehicles ahead of the own vehicle becomes higher.