Vehicle control system

• US 20070191997A1
• Filed: 02/07/2007
• Published: 08/16/2007
• Est. Priority Date: 02/13/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Tsuru, Naohiko, Isaji, Kazuyoshi
• Granted Patent: US 7,433,772 B2
• Time in Patent Office: Days
• US Class Current: 701/1
• CPC Class Codes: B60T 2201/022 Collision avoidance systems
• CPC Class Codes: B60T 2201/08 Lane monitoring; Lane Keeping Systems
• CPC Class Codes: B60T 2201/081 using distance control
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2210/24 Curve radius
• CPC Class Codes: B60T 2210/32 Vehicle surroundings
• CPC Class Codes: B60T 7/22 initiated by contact of vehicle, e.g. bumper, with an external object, e.g. another vehicle , or by means of contactless obstacle detectors mounted on the vehicle
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60W 2420/408 Radar; Laser, e.g. lidar
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2552/30 Road curve radius
• CPC Class Codes: B60W 30/02 Control of vehicle driving stability
• CPC Class Codes: B60W 30/16 Control of distance between vehicles, e.g. keeping a distance to preceding vehicle
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: B60W 40/076 Slope angle of the road
• CPC Class Codes: G08G 1/166 for active traffic, e.g. moving vehicles, pedestrians, bikes
• CPC Class Codes: G08G 1/167 Driving aids for lane monitoring, lane changing, e.g. blind spot detection

Abstract

When a vehicle travels along a curve of a road, a target vehicle acceleration/deceleration that is used for accelerating/decelerating the vehicle to a target vehicle speed, which is set for the curve, is calculated. Based on a comparison between a present vehicle speed of the vehicle and the target vehicle speed, the vehicle is controlled such that an acceleration/deceleration of the vehicle coincides with the target vehicle acceleration/deceleration.

Claims

1. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and a road associated object on a road, wherein the road associated object is an object located along an extension line of a traveling direction of the vehicle, and at a boundary of a curve of the road or in a vicinity of the boundary, wherein the curve exists ahead of the vehicle;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the road associated object, wherein;

the approaching/separating state evaluation index increases when a relative speed between the vehicle and the road associated object increases at a time of approaching of the vehicle to the road associated object; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a curvature radius obtaining means for obtaining a curvature radius of the curve;

a target vehicle speed setting means for setting a target vehicle speed of the vehicle, with which the vehicle travels along the curve, based on the curvature radius of the curve;

a vehicle speed obtaining means for obtaining a current speed of the vehicle;

a target vehicle deceleration calculating means for calculating a target vehicle deceleration, with which the vehicle is controlled to travel so that the vehicle travels along the curve with the target vehicle speed, based on the approaching/separating state evaluation index, the distance, the current speed of the vehicle, and the target vehicle speed; and

a vehicle control means for controlling the vehicle to decelerate such that a deceleration of the vehicle coincides with the target vehicle deceleration, when the current speed of the vehicle is larger than the target vehicle speed.

2. The vehicle control system according to claim 1, wherein the vehicle control means controls the vehicle to maintain the current speed of the vehicle when a difference between the current speed of the vehicle and the target vehicle speed is smaller than a predetermined value.

3. The vehicle control system according to claim 1, wherein:

the target vehicle deceleration calculating means calculates a target vehicle acceleration in addition to the target vehicle deceleration, wherein the vehicle is controlled to travel with the target vehicle acceleration by the vehicle control means so that the vehicle travels along the curve with the target vehicle speed; and

the vehicle control means controls the vehicle to accelerate such that an acceleration of the vehicle coincides with the target vehicle acceleration, when the current speed of the vehicle is smaller than the target vehicle speed.

4. The vehicle control system according to claim 1, wherein the evaluation index calculating means calculates KdB_p, which is a present value of the approaching/separating state evaluation index, using the following equation, given D, which is the distance, and V_s0, which is the current speed of the vehicle:

KdB_—

p=10×

log{|−

2×

V_s0|/(D³×

5×

10<sup>−

8</sup>)}.

5. The vehicle control system according to claim 4, wherein the target vehicle acceleration/deceleration calculating means calculates dV_s0/dt, which is the target vehicle acceleration or deceleration, using the following equation, given V_s0—

_t, which is the target vehicle speed;

dV_s0/dt=7.5×

D²×

10<sup>{(|KdB—

p|/10)−

8}</sup>×

(V_s0−

V<sub>s0—

t</sub>).

6. The vehicle control system according to claim 5, wherein the target vehicle acceleration/deceleration calculating means calculates a final value of the target vehicle acceleration or deceleration by multiplying the target vehicle acceleration or deceleration, respectively, by gain, which is a positive value and is equal to or smaller than one.

7. The vehicle control system according to claim 1, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object, wherein the road associated object includes at least one of a lane marking, a pole, a guardrail, a curbstone, a reflective plate, and a delineator.

8. The vehicle control system according to claim 1, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object using road map data and a position of the vehicle, which is detected by a global positioning system.

9. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and a road associated object on a road, wherein the road associated object is an object located along an extension line of a traveling direction of the vehicle, and at a boundary of a curve of the road or in a vicinity of the boundary, wherein the curve exists ahead of the vehicle;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the road associated object, wherein;

the approaching/separating state evaluation index increases when a relative speed between the vehicle and the road associated object increases at a time of approaching of the vehicle to the road associated object; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a curvature radius obtaining means for obtaining a curvature radius of the curve;

a target vehicle speed setting means for setting a target vehicle speed of the vehicle, with which the vehicle travels along the curve, based on the curvature radius of the curve;

a vehicle speed obtaining means for obtaining a current speed of the vehicle;

a target vehicle acceleration/deceleration calculating means for calculating a target vehicle acceleration or deceleration, with which the vehicle is controlled to travel so that the vehicle travels along the curve with the target vehicle speed, based on the approaching/separating state evaluation index, the distance, the current speed of the vehicle, and the target vehicle speed; and

a vehicle control means for controlling the vehicle such that an acceleration or deceleration of the vehicle coincides with the target vehicle acceleration or deceleration, respectively, based on a comparison between the current speed of the vehicle and the target vehicle speed.

10. The vehicle control system according to claim 9, wherein:

the vehicle control means controls the vehicle to decelerate such that the deceleration of the vehicle coincides with the target vehicle deceleration when the current speed of the vehicle is larger than the target vehicle speed; and

the vehicle control means controls the vehicle to accelerate such that the acceleration of the vehicle coincides with the target vehicle acceleration when the current speed of the vehicle is smaller than the target vehicle speed.

11. The vehicle control system according to claim 9, wherein the vehicle control means controls the vehicle to maintain the current speed of the vehicle when a difference between the current speed of the vehicle and the target vehicle speed is smaller than a predetermined value.

12. The vehicle control system according to claim 9, wherein the evaluation index calculating means calculates KdB_p, which is a present value of the approaching/separating state evaluation index, using the following equation, given D, which is the distance, and V_s0, which is the current speed of the vehicle:

KdB_—

p=10×

log{|−

2×

V_s0|/(D³×

5×

10<sup>−

8</sup>)}.

13. The vehicle control system according to claim 12, wherein the target vehicle acceleration/deceleration calculating means calculates dV_s0/dt, which is the target vehicle acceleration or deceleration, using the following equation, given V_s0—

_t, which is the target vehicle speed;

dV_s0/dt=7.5×

D²×

10<sup>{(|KdB—

p|/10)−

8}</sup>×

(V_s0−

V<sub>s0—

t</sub>).

14. The vehicle control system according to claim 13, wherein the target vehicle acceleration/deceleration calculating means calculates a final value of the target vehicle acceleration or deceleration by multiplying the target vehicle acceleration or deceleration, respectively, by gain, which is a positive value and is equal to or smaller than one.

15. The vehicle control system according to claim 9, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object, wherein the road associated object includes at least one of a lane marking, a pole, a guardrail, a curbstone, a reflective plate, and a delineator.

16. The vehicle control system according to claim 9, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object using road map data and a position of the vehicle, which is detected by a global positioning system.

17. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and an obstruction on a road, wherein the obstruction exists on the road, which is ahead of the vehicle in a traveling direction of the vehicle;

a relative speed obtaining means for obtaining a relative speed between the vehicle and the obstruction;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the obstruction, wherein;

the approaching/separating state evaluation index increases when the relative speed increases at a time of approaching of the vehicle to the obstruction; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a turning radius calculating means for calculating a turning radius of the vehicle, which is necessary for the vehicle to avoid a collision with the obstruction, based on the distance;

a target lateral acceleration setting means for setting a target value of a lateral acceleration, which is generated in the vehicle in a lateral direction of the vehicle through a steering operation by a driver of the vehicle to avoid the collision;

a target relative speed calculating means for calculating a target relative speed between the vehicle and the obstruction based on the turning radius and the target value of the lateral acceleration;

a target relative deceleration calculating means for calculating a target relative deceleration between the vehicle and the obstruction based on the distance, the relative speed, and the approaching/separating state evaluation index; and

a vehicle control means for controlling the vehicle to decelerate such that a relative deceleration between the vehicle and the obstruction coincides with the target relative deceleration when the relative speed is larger than the target relative speed, wherein the vehicle is controlled to travel with the target relative deceleration by the vehicle control means so that the vehicle is decelerated to the target relative speed.

18. The vehicle control system according to claim 17, wherein the target relative deceleration calculating means calculates a final value of the target relative deceleration by multiplying the target relative deceleration by gain, which is a positive value and is equal to or smaller than one.

19. The vehicle control system according to claim 17, further comprising:

a road surface friction coefficient determining means for determining a friction coefficient between a tire of the vehicle and a surface of the road that is ahead of the vehicle in the traveling direction of the vehicle; and

a maximum deceleration calculating means for calculating a maximum deceleration that is generable in the vehicle based on the friction coefficient, wherein the vehicle control means controls the vehicle such that the relative deceleration is smaller than the maximum deceleration.

20. The vehicle control system according to claim 17, further comprising a vehicle projection plane locus estimating means for estimating a future locus of a projection plane of the vehicle based on a traveling state of the vehicle, wherein:

the projection plane of the vehicle is a plane that has an area of a width and height of the vehicle; and

the future locus of the projection plane is a virtual three-dimensional track left by the projection plane along the road when it is hypothesized that the projection plane travels with a present traveling state of the vehicle maintained, wherein the distance obtaining means obtains the distance between the vehicle and the obstruction, which overlaps with the future locus of the projection plane of the vehicle.

21. The vehicle control system according to claim 20, wherein the vehicle projection plane locus estimating means estimates the future locus of the projection plane of the vehicle in view of a minimum ground clearance of the vehicle.

22. The vehicle control system according to claim 17, wherein the evaluation index calculating means calculates KdB_p, which is a present value of the approaching/separating state evaluation index, using the following equation, given V_r, which is the relative speed and D, which is the distance:

KdB_—

p=10×

log{|−

2×

V_r|/(D³×

5×

10<sup>−

8</sup>)}.

23. The vehicle control system according to claim 22, wherein the target relative deceleration calculating means calculates dV_r/dt, which is the target relative deceleration, using the following equation, given V_r—

_t, which is the target relative speed;

dV_r/dt=7.5×

D²×

10<sup>{(|KdB—

p|/10)−

8}</sup>×

(V_r−

V<sub>r—

t</sub>).

24. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and one of an obstruction and a road associated object, wherein;

the vehicle travels along a road;

the obstruction exists on a curve of the road, wherein the curve exists ahead of the vehicle in a traveling direction of the vehicle; and

the road associated object is an object located at a boundary of the curve or in a vicinity of the boundary;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the one of the obstruction and the road associated object, wherein;

the approaching/separating state evaluation index increases when a relative speed between the vehicle and the one of the obstruction and the road associated object increases at a time of approaching of the vehicle to the one of the obstruction and the road associated object; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a curvature radius obtaining means for obtaining a curvature radius of the curve;

a target vehicle speed setting means for setting a target vehicle speed of the vehicle, with which the vehicle travels along the curve, based on the curvature radius of the curve;

a vehicle speed obtaining means for obtaining a current speed of the vehicle;

a relative speed obtaining means for obtaining the relative speed between the vehicle and the obstruction;

a turning radius calculating means for calculating a turning radius of the vehicle, which is necessary for the vehicle to avoid a collision with the obstruction, based on the distance between the vehicle and the obstruction;

a target lateral acceleration setting means for setting a target value of a lateral acceleration, which is generated in the vehicle in a lateral direction of the vehicle through a steering operation by a driver of the vehicle to avoid the collision;

a target relative speed calculating means for calculating a target relative speed between the vehicle and the obstruction based on the turning radius and the target value of the lateral acceleration;

a target vehicle acceleration/deceleration calculating means for calculating a target vehicle acceleration or deceleration, with which the vehicle is controlled to travel so that the vehicle travels along the curve with the target vehicle speed, based on the approaching/separating state evaluation index between the vehicle and the road associated object, the distance between the vehicle and the road associated object, the current speed of the vehicle, and the target vehicle speed;

a target relative deceleration calculating means for calculating a target relative deceleration between the vehicle and the obstruction based on the distance between the vehicle and the obstruction, the relative speed, and the approaching/separating state evaluation index between the vehicle and the obstruction; and

a vehicle control means for controlling the vehicle to decelerate such that a relative deceleration between the vehicle and the obstruction coincides with the target relative deceleration when the obstruction exists on the curve and the relative speed is larger than the target relative speed, wherein the vehicle is controlled to travel with the target relative deceleration by the vehicle control means so that the vehicle is decelerated to the target relative speed, and controlling the vehicle such that an acceleration or deceleration of the vehicle coincides with the target vehicle acceleration or deceleration, respectively, based on a comparison between the current speed of the vehicle and the target vehicle speed when the obstruction does not exist on the curve.

25. The vehicle control system according to claim 24, wherein the vehicle control means controls the vehicle to decelerate such that the deceleration of the vehicle coincides with the target vehicle deceleration when the current speed of the vehicle is larger than the target vehicle speed, and controls the vehicle to accelerate such that the acceleration of the vehicle coincides with the target vehicle acceleration when the current speed of the vehicle is smaller than the target vehicle speed.

26. The vehicle control system according to claim 24, wherein the vehicle control means controls the vehicle to maintain the current speed of the vehicle when a difference between the current speed of the vehicle and the target vehicle speed is smaller than a predetermined value.

27. The vehicle control system according to claim 24, wherein the evaluation index calculating means calculates KdB_p, which is a present value of the approaching/separating state evaluation index between the vehicle and the road associated object, using the following equation, given V_s0, which is the current speed of the vehicle, and D, which is the distance between the vehicle and the road associated object:

KdB_—

p=10×

log{|−

2×

V_s0|/(D³×

5×

10<sup>−

8</sup>)}.

28. The vehicle control system according to claim 27, wherein the target vehicle acceleration/deceleration calculating means calculates dV_s0/dt, which is the target vehicle acceleration or deceleration, using the following equation, given V_s0—

_t, which is the target vehicle speed;

dV_s0/dt=7.5×

D²×

10<sup>{(|KdB—

p|/10)−

8}</sup>×

(V_s0−

V<sub>s0—

t</sub>).

29. The vehicle control system according to claim 28, wherein the target vehicle acceleration/deceleration calculating means calculates a final value of the target vehicle acceleration or deceleration by multiplying the target vehicle acceleration or deceleration by gain, which is a positive value and is equal to or smaller than one.

30. The vehicle control system according to claim 24, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object, wherein the road associated object includes at least one of a lane marking, a pole, a guardrail, a curbstone, a reflective plate, and a delineator.

31. The vehicle control system according to claim 24, wherein the distance obtaining means obtains the distance between the vehicle and the road associated object using road map data and a position of the vehicle, which is detected by a global positioning system.

32. The vehicle control system according to claim 24, wherein the target relative deceleration calculating means calculates a final value of the target relative deceleration by multiplying the target relative deceleration by gain, which is a positive value and is equal to or smaller than one.

33. The vehicle control system according to claim 24, further comprising:

a road surface friction coefficient determining means for determining a friction coefficient between a tire of the vehicle and a surface of the road that is ahead of the vehicle in the traveling direction of the vehicle; and

a maximum deceleration calculating means for calculating a maximum deceleration that is generable in the vehicle based on the friction coefficient, wherein the vehicle control means controls the vehicle such that the relative deceleration between the vehicle and the obstruction is smaller than the maximum deceleration.

34. The vehicle control system according to claim 24, further comprising a vehicle projection plane locus estimating means for estimating a future locus of a projection plane of the vehicle based on a traveling state of the vehicle, wherein:

the projection plane of the vehicle is a plane that has an area of a width and height of the vehicle; and

the future locus of the projection plane is a virtual three-dimensional track left by the projection plane along the road when it is hypothesized that the projection plane travels with a present traveling state of the vehicle maintained, wherein the distance obtaining means obtains the distance between the vehicle and the obstruction, which overlaps with the future locus of the projection plane of the vehicle.

35. The vehicle control system according to claim 34, wherein the vehicle projection plane locus estimating means estimates the future locus of the projection plane of the vehicle in view of a minimum ground clearance of the vehicle.

36. The vehicle control system according to claim 24, wherein the evaluation index calculating means calculates KdB_p, which is a present value of the approaching/separating state evaluation index between the vehicle and the obstruction, using the following equation, given V_r, which is the relative speed between the vehicle and the obstruction, and D, which is the distance between the vehicle and the obstruction:

KdB_—

p=10×

log{|−

2×

V_r|/(D³×

5×

10<sup>−

8</sup>)}.

37. The vehicle control system according to claim 36, wherein the target relative deceleration calculating means calculates dV_r/dt, which is the target relative deceleration, using the following equation, given V_r—

_t, which is the target relative speed;

dV_r/dt=7.5×

D²×

10<sup>{(|KdB—

p|/10)−

8}</sup>×

(V_r−

V<sub>r—

t</sub>).

38. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and a road associated object on a road, wherein the road associated object is an object located along an extension line of a traveling direction of the vehicle, and at a boundary of a curve of the road or in a vicinity of the boundary, wherein the curve exists ahead of the vehicle;

a relative speed detecting means for detecting a relative speed between the vehicle and the road associated object;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the road associated object, wherein;

the approaching/separating state evaluation index increases when the relative speed increases, at a time of approaching of the vehicle to the road associated object; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a deceleration target calculating means for calculating a deceleration target based on a normal deceleration of the vehicle, the distance, and the relative speed, wherein the deceleration target indicates an index of a timing, with which braking force applied through a brake system of the vehicle when the vehicle proceeds into the curve or travels along the curve is controlled;

a deceleration target determining means for determining whether the approaching/separating state evaluation index is larger than the deceleration target;

a target value setting means for setting a target value of the approaching/separating state evaluation index, such that the target value of the approaching/separating state evaluation index increases linearly from an initial value at a constant slope when the distance decreases, wherein;

the initial value is the approaching/separating state evaluation index at a time when the deceleration target determining means determines that the approaching/separating state evaluation index is larger than the deceleration target; and

the constant slope is a slope of the approaching/separating state evaluation index at the time when the deceleration target determining means determines that the approaching/separating state evaluation index is larger than the deceleration target;

a target vehicle deceleration calculating means for calculating a target vehicle deceleration based on a target relative speed between the vehicle and the road associated object, and a present relative speed between the vehicle and the road associated object, wherein the target relative speed is obtained based on the target value of the approaching/separating state evaluation index; and

a braking force control means for controlling the braking force applied through the brake system such that a deceleration of the vehicle coincides with the target vehicle deceleration when the vehicle proceeds into the curve or travels along the curve.

39. The vehicle control system according to claim 38, further comprising a collision time allowance calculating means for calculating a collision time allowance that indicates a time allowance before the vehicle collides with the road associated object, wherein the braking force control means does not control the braking force when the collision time allowance is equal to or longer than a predetermined amount of time.

40. The vehicle control system according to claim 38, wherein the target value setting means multiplies the slope of the approaching/separating state evaluation index by gain, which is determined by a driver of the vehicle, and sets the target value of the approaching/separating state evaluation index using the slope multiplied by the gain.

41. A vehicle control system for controlling a vehicle, comprising:

a distance obtaining means for obtaining a distance between the vehicle and a road associated object on a road, wherein the road associated object is an object located along an extension line of a traveling direction of the vehicle, and at a boundary of a curve of the road or in a vicinity of the boundary, wherein the curve exists ahead of the vehicle;

a relative speed detecting means for detecting a relative speed between the vehicle and the road associated object;

an evaluation index calculating means for calculating an approaching/separating state evaluation index that indicates a positional relationship between the vehicle and the road associated object, wherein;

the approaching/separating state evaluation index increases when the relative speed increases at a time of approaching of the vehicle to the road associated object; and

the approaching/separating state evaluation index for the relative speed increases at a faster rate as the distance decreases;

a target value setting means for setting a target value of the approaching/separating state evaluation index, such that the target value of the approaching/separating state evaluation index increases linearly from an initial value at a constant slope when the distance decreases, wherein;

the initial value is the approaching/separating state evaluation index at a time when a driver of the vehicle starts a drive operation to decelerate the vehicle when the vehicle proceeds into the curve or travels along the curve; and

the constant slope is a slope of the approaching/separating state evaluation index at the time when the driver starts the drive operation to decelerate the vehicle;

a target vehicle deceleration calculating means for calculating a target vehicle deceleration based on a target relative speed between the vehicle and the road associated object and a present relative speed between the vehicle and the road associated object, wherein the target relative speed is obtained based on the target value of the approaching/separating state evaluation index; and

a braking force control means for controlling braking force, which is applied through a brake system of the vehicle, such that a deceleration of the vehicle coincides with the target vehicle deceleration, when the vehicle proceeds into the curve or travels along the curve.

42. The vehicle control system according to claim 41, further comprising a deceleration estimating means for estimating the deceleration of the vehicle, which is generated through the drive operation by the driver to decelerate the vehicle, wherein the braking force control means does not control the braking force when the deceleration of the vehicle is larger than the target vehicle deceleration.

43. The vehicle control system according to claim 41, further comprising a collision time allowance calculating means for calculating a collision time allowance that indicates a time allowance before the vehicle collides with the road associated object, wherein the braking force control means does not control the braking force when the collision time allowance is equal to or longer than a predetermined amount of time.

44. The vehicle control system according to claim 41, wherein the target value setting means multiplies the slope of the approaching/separating state evaluation index by gain, which is determined by a driver of the vehicle, and sets the target value of the approaching/separating state evaluation index using the slope multiplied by the gain.