JP4862313B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicle speed control device and a vehicle behavior control device, and more particularly, to a vehicle travel control device including a lane departure prevention device.

2. Description of the Related Art In recent years, when a host vehicle is about to depart from a travel lane, the vehicle travels with a lane departure prevention device that prevents the departure and a vehicle speed control device that controls the vehicle speed so as to follow the target vehicle. Some vehicles are equipped with a control device.
Here, as a lane departure prevention device, when there is a possibility that the host vehicle departs from the traveling lane, a braking force difference is applied to the left and right wheels, and a yaw moment is applied to the host vehicle so that the host vehicle is traveling in the traveling lane. There is a device that prevents the deviation from the above (see, for example, Patent Document 1).

As a vehicle speed control device, there is an ACC (adaptive cruise control) system that controls the vehicle speed so as to keep the distance between the vehicle and the vehicle ahead. Such a vehicle speed control device includes a device that sets an inter-vehicle distance control gain (travel control gain, vehicle speed control gain, etc.) based on the set inter-vehicle distance (see, for example, Patent Document 2). In this vehicle speed control device, when the set inter-vehicle distance is short, the inter-vehicle distance control gain is increased to make the vehicle behavior agile, and when the set inter-vehicle distance is long, the inter-vehicle distance control gain is reduced to slow down the vehicle behavior. It ’s a good thing.
Japanese Patent Laid-Open No. 2003-112540 JP 2004-268642 A

However, even if the vehicle is equipped with a conventional vehicle speed control device that sets the inter-vehicle distance control gain based on the set inter-vehicle distance, the lane departure prevention device has a predetermined size or predetermined value regardless of the set inter-vehicle distance. The yaw moment is applied to the host vehicle at the timing. That is, in the vehicle speed control, although the set inter-vehicle distance is taken into consideration, such consideration is not made in the lane departure prevention control. In this case, the sense of control (vehicle behavior) felt by the driver differs depending on the set inter-vehicle distance between the vehicle speed control and the lane departure prevention control, and the driver feels uncomfortable.
The present invention has been made in view of the above-described problems, and aims to provide a vehicle travel control device that cooperates with vehicle speed control and lane departure prevention control to prevent the driver from feeling uncomfortable. To do.

According to a first aspect of the present invention, there is provided a vehicle travel control device comprising: a vehicle speed control device that controls a vehicle speed so as to follow a preceding vehicle; and a vehicle behavior control device that controls a vehicle behavior of the host vehicle according to a travel state of the host vehicle. This is a travel control device for a vehicle to be mounted.
The vehicle travel control device includes an inter-vehicle distance setting means for the driver to set an inter-vehicle distance from the preceding vehicle during vehicle speed control by the vehicle speed control device, and the forward vehicle set by the driver. Control characteristic changing means for changing the control characteristic of the vehicle behavior control device to match the driver's intention based on the set inter-vehicle distance, and the vehicle behavior control device with respect to the traveling lane A lane departure prevention device that performs lane departure prevention control for preventing the vehicle from deviating from the travel lane when the host vehicle tends to depart, wherein the control characteristic changing means increases the vehicle distance as the set inter-vehicle distance increases. The control characteristics of the lane departure prevention control are changed so that the behavior becomes sluggish and the vehicle behavior becomes more agile as the set inter-vehicle distance is shorter.

  According to the vehicle travel control device of the first aspect, by setting the control characteristics of the vehicle behavior control device so as to match the driver's intention when the set inter-vehicle distance is set, the vehicle behavior control device The vehicle behavior by the control matches the driver's intention according to the set inter-vehicle distance.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
The embodiment is a rear-wheel drive vehicle equipped with an ACC (Adaptive Cruise Control) system and a lane departure prevention device that constitute the vehicle travel control device according to the present invention. This rear-wheel drive vehicle is equipped with an automatic transmission and a conventional differential gear, and a braking device capable of independently controlling the braking force of the left and right wheels for both the front and rear wheels.

FIG. 1 is a schematic configuration diagram showing the present embodiment.
In the figure, reference numeral 1 is a brake pedal, 2 is a booster, 3 is a master cylinder, and 4 is a reservoir. It supplies to each wheel cylinder 6FL-6RR of each wheel 5FL-5RR. Further, a braking fluid pressure control unit 7 is interposed between the master cylinder 3 and each wheel cylinder 6FL-6RR, and the braking fluid pressure control unit 7 controls the braking fluid pressure of each wheel cylinder 6FL-6RR. Individual control is also possible.

The braking fluid pressure control unit 7 uses a braking fluid pressure control unit used for antiskid control and traction control, for example. The brake fluid pressure control unit 7 can control the brake fluid pressure of each of the wheel cylinders 6FL to 6RR independently, but when a brake fluid pressure command value is input from the braking / driving force control unit 8 described later, The brake fluid pressure is controlled according to the brake fluid pressure command value.
For example, the brake fluid pressure control unit 7 includes an actuator in the hydraulic pressure supply system. Examples of the actuator include a proportional solenoid valve capable of controlling each wheel cylinder hydraulic pressure to an arbitrary braking hydraulic pressure.

  The vehicle is provided with a drive torque control unit 12. The drive torque control unit 12 controls the drive torque to the rear wheels 5RL and 5RR which are drive wheels by controlling the operating state of the engine 9, the selected gear ratio of the automatic transmission 10, and the throttle opening of the throttle valve 11. To do. The drive torque control unit 12 controls the operating state of the engine 9 by controlling the fuel injection amount and ignition timing, and simultaneously controlling the throttle opening. The drive torque control unit 12 outputs the value of the drive torque Tw used for control to the braking / driving force control unit 8.

The drive torque control unit 12 can control the drive torque of the rear wheels 5RL and 5RR independently. However, when a drive torque command value is input from the braking / driving force control unit 8, the drive torque is controlled. Drive wheel torque is also controlled according to the command value.
In addition, this vehicle is provided with an imaging unit 13 with an image processing function. The imaging unit 13 is provided for detecting the position of the host vehicle in the traveling lane for detecting the lane departure tendency of the host vehicle. For example, the imaging unit 13 is configured to capture an image with a monocular camera including a CCD (Charge Coupled Device) camera. This imaging part 13 is installed in the front part of the vehicle.

The imaging unit 13 detects a lane marker such as a white line from a captured image in front of the host vehicle, and detects a traveling lane based on the detected lane marker. Further, the imaging unit 13 determines, based on the detected travel lane, an angle (yaw angle) φ between the travel lane of the host vehicle and the longitudinal axis of the host vehicle, a lateral displacement X from the center of the travel lane, and a travel lane curvature. β and the like are calculated. The imaging unit 13 outputs the calculated yaw angle φ, lateral displacement X, travel lane curvature β, and the like to the braking / driving force control unit 8.
In the present invention, the lane marker may be detected by detection means other than image processing. For example, the lane marker may be detected by a plurality of infrared sensors attached to the front of the vehicle, and the traveling lane may be detected based on the detection result.

  Further, the present invention is not limited to the configuration in which the traveling lane is determined based on the white line. In other words, if there is no white line (lane marker) on the road to recognize the driving lane, the information on the road shape and surrounding environment obtained by image processing and various sensors, the driving range suitable for driving and driving A person may estimate the travel range where the vehicle should travel and determine the travel lane. For example, when there is no white line on the runway and both sides of the road are separated, the asphalt portion of the runway is determined as the travel lane. Moreover, what is necessary is just to determine a driving lane in consideration of the information, when there are a guardrail, a curb, etc.

Further, the traveling lane curvature β may be calculated based on a steering angle δ of the steering wheel 21 described later.
The vehicle is provided with a navigation device 14. The navigation device 14 detects the longitudinal acceleration Yg or lateral acceleration Xg generated in the host vehicle or the yaw rate φ ′ generated in the host vehicle. The navigation device 14 outputs the detected longitudinal acceleration Yg, lateral acceleration Xg, and yaw rate φ ′ to the braking / driving force control unit 8 together with road information. Here, the road information includes road type information indicating the number of lanes and whether the road is a general road or a highway.

Each value may be detected by a dedicated sensor. That is, the longitudinal acceleration Yg and the lateral acceleration Xg may be detected by the acceleration sensor, and the yaw rate φ ′ may be detected by the yaw rate sensor.
The vehicle is also provided with a radar 16 for measuring the distance between the host vehicle and the front obstacle by sweeping laser light forward and receiving the reflected light from the preceding obstacle. ing.
The radar 16 then outputs information on the position of the front obstacle to the braking / driving force control unit 8. The detection result by the radar 16 is used for processing in an ACC, a rear-end collision speed reducing brake device, or the like.

  Further, in this vehicle, a master cylinder pressure sensor 17 that detects an output pressure of the master cylinder 3, that is, master cylinder hydraulic pressures Pmf and Pmr, and an accelerator opening sensor 18 that detects an accelerator pedal depression amount, that is, an accelerator opening θt. , A steering angle sensor 19 for detecting a steering angle (steering angle) δ of the steering wheel 21, a direction indicating switch 20 for detecting a direction indicating operation by a direction indicator, and a rotation speed of each of the wheels 5FL to 5RR, so-called wheel speed Vwi. Wheel speed sensors 22FL to 22RR for detecting (i = fl, fr, rl, rr) are provided. Detection signals detected by these sensors and the like are output to the braking / driving force control unit 8.

When the detected vehicle traveling state data has left and right directions, the right direction is the positive direction in all cases. That is, the yaw rate φ ′, the lateral acceleration Xg, and the yaw angle φ are positive values when turning right, and the lateral displacement X is a positive value when deviating from the center of the traveling lane to the right. The longitudinal acceleration Yg takes a positive value during acceleration and takes a negative value during deceleration.
Various data is input to the braking / driving force control unit 8 as described above, and ACC and lane departure prevention control is performed based on the input data.

A system that performs ACC (preceding vehicle follow-up running control) is configured as follows.
As shown in FIG. 2, the braking / driving force control unit 8 has a vehicle speed signal processing unit 31 that calculates the vehicle speed based on data obtained by the wheel speed sensors 22FL to 22RR, as shown in FIG. The time from when the laser beam is swept by the radar 16 until the reflected light from the front vehicle (front obstacle) existing in front of the host vehicle on the traveling lane of the host vehicle is measured, and the preceding vehicle and the host vehicle are measured. A distance measurement signal processing unit 34 that calculates an inter-vehicle distance L between the vehicle and the vehicle speed Vsp calculated by the vehicle speed signal processing unit 31 and an inter-vehicle distance L between the preceding vehicle calculated by the distance measurement signal processing unit 34 sets a target inter-vehicle distance L ^*, a travel control unit 40 for calculating a target vehicle speed V ^* for maintaining the inter-vehicle distance L to the target inter-vehicle distance L ^*, target vehicle speed V calculated in the travel controller 40 ^* Based on , So to match the vehicle speed Vsp on the target vehicle speed V ^*, the braking hydraulic pressure controller 7, a vehicle speed control unit 33 for controlling the automatic transmission such that drive torque controller 12 and not shown, further, from the imaging unit 13 And an image processing unit 32 for processing imaging information.
In actual control, a value obtained by dividing the inter-vehicle distance by the own vehicle speed, that is, the head time is used as the “inter-vehicle distance”. Therefore, the target inter-vehicle distance L ^* also has a dimension value corresponding to such a vehicle head time.

The travel control unit 40 is input from the vehicle speed signal processing unit 31 and the relative speed calculation unit 41 that calculates the relative speed ΔV between the host vehicle and the preceding vehicle based on the inter-vehicle distance L calculated by the ranging signal processing unit 34. The target vehicle distance L based on the vehicle speed Vsp and the relative speed ΔV calculated by the relative speed calculation unit 41 or the inter-vehicle distance setting value (also referred to as the set inter-vehicle distance) Ls set by the driver by operating the manual switch. ^* , And the target inter-vehicle distance setting unit 42 that corrects the target inter-vehicle distance L ^* based on the travel environment information from the navigation device 14 and the like, the relative speed ΔV calculated by the relative speed calculation unit 41, and the distance measurement signal processing based on the running environment information from the inter-vehicle distance L and the navigation apparatus 14 calculated in section 34, the inter-vehicle distance L to the target inter-vehicle distance calculated by the target inter-vehicle distance setting section 42 L ^* And a distance control unit 43 for calculating a target vehicle speed V ^* for matching.

Then, the vehicle speed control unit 33 calculates the target acceleration / deceleration by a known procedure by, for example, PID (proportional-integral-derivative) control from the difference value between the target vehicle speed V ^* and the host vehicle speed Vsp, and the target acceleration / deceleration is a negative value. If this is the case, the braking fluid pressure control unit 7 is controlled to generate a braking force so that this target acceleration / deceleration can be realized. Conversely, when the target acceleration / deceleration is a positive value, the target acceleration / deceleration is achieved. The drive torque control unit 12 and an automatic transmission (not shown) are controlled so that the speed can be realized.

Next, the ranging signal processing unit 34 and the travel control unit 40 will be described in detail.
First, a method for calculating the relative speed ΔV will be described. As shown in FIGS. 3 and 4, the relative speed ΔV is approximately obtained using the band-pass filter or the high-pass filter with the inter-vehicle distance L to the preceding vehicle calculated by the ranging signal processing unit 34 as an input. Can do. For example, the bandpass filter can be realized by a transfer function expressed by the following equation (1).
F (s) = ωc ² · s / (s ² + 2ζ · ωc · s + ωc ² ) (1)
In equation (1), ωc = 2π · fc, s is a Laplace operator, and ζ is an attenuation coefficient. The cut-off frequency fc of the filter function is determined by the magnitude of the noise component included in the inter-vehicle distance L and the allowable value of the short-cycle vehicle body longitudinal acceleration fluctuation.

Next, a control law for traveling while keeping the inter-vehicle distance L at the target inter-vehicle distance L ^* will be described. As shown in FIG. 2, the basic control system has a configuration in which a travel control unit 40 and a vehicle speed control unit 33 are provided independently. Note that the output of the travel control unit 40 is a target vehicle speed (vehicle speed command value) V ^* and is not configured to directly control the inter-vehicle distance L.

The inter-vehicle distance control unit 43 of the travel control unit 40 calculates a target vehicle speed V ^* for traveling while maintaining the inter-vehicle distance L at the target inter-vehicle distance L ^* based on the inter-vehicle distance L and the relative speed ΔV. Specifically, as shown in the following equation (2), a value obtained by multiplying the difference (L ^* −L) between the target inter-vehicle distance L ^* and the actual inter-vehicle distance L by the control gain fd and the relative speed ΔV are controlled. ΔV ^* , which is the sum of values multiplied by the gain fv, is calculated, and a value obtained by subtracting this from the vehicle speed Vt of the preceding vehicle is set as the target vehicle speed V ^* (see FIG. 5).
V ^* = Vt−ΔV ^*
ΔV ^* = fd · (L ^* −L) + fv · ΔV
... (2)
The control gains fd and fv are parameters that determine the travel control capability. Here, since it is a 1-input 2-output system that controls two target values (inter-vehicle distance and relative speed) with one input (target vehicle speed), the control system uses state feedback (regulator) as a control method. Is designing.

Next, the design procedure of the control system will be described.
First, system state variables x ₁ and x 2 are defined by the following equation (3).
x ₁ = Vt−V
x ₂ = ^L * -L
... (3)
Further, the control input (controller output) ΔV ^* is defined by the following equation (4).
ΔV ^* = Vt−V ^* (4)
Here, the inter-vehicle distance L can be expressed as the following equation (5).
L = ∫ (Vt−V) dt + L ₀ (5)
Incidentally, L ₀ in equation (5) is a target inter-vehicle distance at the time of stopping the adaptive cruise control.

Further, the vehicle speed servo system can approximately represent the actual vehicle speed V with a first-order lag with respect to the target vehicle speed V ^* by a linear transfer function, for example, as shown in the following equation (6).
V = 1 / (1 + τv · s)
dV / dt = 1 / τv (V ^* −V)
... (6)
Therefore, when a constant speed Vt of the preceding vehicle, the equation (3) and (4) and (6), the state variable x ₁ can be expressed by the following equation (7).
dx ₁ / dt = −1 / τv · x ₁ + 1 / τv · ΔV ^* (7)
Further, when the target inter-vehicle distance L ^* is constant, than the (3) and (5), the state variable x ₂ can be expressed by the following equation (8).
x ₂ = − (Vt−V) = − x ₁ (8)
Therefore, the state equation of the system can be expressed by the following equation (9) from the equations (7) and (8).

Further, the state equation of the entire system subjected to state feedback can be expressed by the following equation (10).
dX / dt = (A + BF) X (10)
However, control input u = FX, F = [fv fd].
Therefore, from the equation (10), the characteristic equation of the entire system can be expressed by the following equation (11).
| SI−A ′ | = s ² + (1−fv) / τv · s + fd / τv = 0
A ′ = A + BF (11)

Here, the vehicle speed servo system of the vehicle speed control unit 33 can be approximately expressed by a linear transfer function. Based on this transfer characteristic, the inter-vehicle distance L converges to the target inter-vehicle distance L ^* and the relative speed ΔV converges to 0, respectively. The control gains fd and fv are set according to the following equation (12) so that the convergence characteristics to be achieved are the characteristics (damping coefficient ζ, natural frequency ωn) intended by the designer.
fv = 1-2ζ · ωn · τv
fd = ωn ² · τv
(12)

Here, as shown in FIG. 6, since the relative speed ΔV is a difference between the vehicle speeds of the preceding vehicle and the host vehicle, the vehicle speed Vt of the preceding vehicle is expressed by the following equation (13) based on the host vehicle speed V and the relative speed ΔV. It can be calculated from
Vt = V + ΔV (13)
Therefore, the target vehicle speed V ^* can be expressed by the following equation (14) from the equations (2) and (13).
V ^* = V−fd (L ^* −L) + (1−fv) ΔV (14)

The target inter-vehicle distance L ^* may be set using the concept of inter-vehicle time used for approach warnings, etc., but here a function of the vehicle speed Vt of the preceding vehicle from the viewpoint of not affecting the convergence of the control at all. And Using the vehicle speed Vt of the preceding vehicle defined by the equation (13), the target inter-vehicle distance L ^* is set as shown in the following equation (15).
L ^* = a · Vt + L ₀ = a · (V + ΔV) + L ₀ (15)

As shown in equation (15), when the target inter-vehicle distance L ^* is set using the vehicle speed Vt of the preceding vehicle calculated from the host vehicle speed V and the relative speed ΔV, the noise superimposed on the detected relative speed value Therefore, the target inter-vehicle distance L ^* represented by the following equation (16) may be set as a function of the host vehicle speed V, as shown in FIG.
L ^* = a · V + L ₀ (16)

In the inter-vehicle distance control unit 43, when the target inter-vehicle distance L ^* set in this way is less than the inter-vehicle distance set value Ls set by the manual switch, the inter-vehicle distance set value Ls is used as the target inter-vehicle distance. It is set as L ^* .
Here, an example of the structure of the manual switch will be described.
As shown in FIG. 8, the steering wheel 21 is provided with a manual switch 23 for adjusting the traveling state of the host vehicle by a driver's manual input. In the figure, reference numeral 23a is a start switch for travel control including forward vehicle following travel control, 23b is a travel control release switch, 23c is a set inter-vehicle distance switch for inputting a set inter-vehicle distance, and 23d is for inputting a set travel speed. A set / coast switch 23e for changing the set travel speed in the deceleration direction, and a resume / accelerate switch 23e for re-inputting the previous set travel speed or changing the set travel speed in the acceleration direction after canceling the travel control.

Here, the driver can manually set the inter-vehicle distance by the set inter-vehicle distance switch 23c. The set inter-vehicle distance switch 23c does not employ a method of inputting a specific set inter-vehicle distance numerically, but is used when, for example, it is desired to increase or decrease the current inter-vehicle distance. When the most standard target inter-vehicle distance is set to “medium” with respect to the running speed of the vehicle, an input method such as “long” that makes the set inter-vehicle distance larger than that or “short” that makes the set inter-vehicle distance smaller than that Adopted.
The above is the control law for driving the host vehicle while keeping the inter-vehicle distance L at the target inter-vehicle distance L ^* .

Next, the processing content of lane departure prevention control is demonstrated.
A processing procedure of lane departure prevention control performed by the braking / driving force control unit 8 will be described with reference to FIG. This process is executed by timer interruption every predetermined sampling time ΔT every 10 msec., For example. Although no communication process is provided in the process shown in FIG. 8, information obtained by the arithmetic process is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.

  First, in step S1, various data are read from each sensor, controller, or control unit. Specifically, the longitudinal acceleration Yg, lateral acceleration Xg, yaw rate φ ′ and road information obtained by the navigation device 14, road speed Vwi, steering angle δ, accelerator opening θt, master cylinder hydraulic pressure detected by each sensor Pmf, Pmr, direction switch signal, drive torque Tw from the drive torque control unit 12, and yaw angle φ, lateral displacement X, and travel lane curvature β are read from the imaging unit 13.

Subsequently, in step S2, the vehicle speed V is calculated. Specifically, the vehicle speed V is calculated by the following equation (17) based on the wheel speed Vwi read in step S1.
For front wheel drive V = (Vwr1 + Vwrr) / 2
For rear wheel drive V = (Vwfl + Vwfr) / 2
... (17)
Here, Vwfl and Vwfr are the wheel speeds of the left and right front wheels, and Vwrl and Vwrr are the wheel speeds of the left and right rear wheels. That is, in the equation (17), the vehicle speed V is calculated as the average value of the wheel speeds of the driven wheels. In this embodiment, since the vehicle is a rear-wheel drive vehicle, the vehicle speed V is calculated from the latter equation, that is, the wheel speed of the front wheels.

The vehicle speed V calculated in this way is preferably used during normal travel. For example, when an ABS (Anti-lock Brake System) control or the like is operating, an estimated vehicle speed estimated in the ABS control is used as the vehicle speed V. A value used for navigation information in the navigation device 14 may be used as the vehicle speed V.
Subsequently, in step S3, a lane departure determination time is set.

Here, in the determination of the lane departure tendency will be described later, are performed on the running state of the vehicle after a predetermined time T _TLC, the predetermined time T _TLC is a lane departure determination time. For example, the relationship between the estimated lateral displacement Xs of the lateral position of the center of gravity of the vehicle after a predetermined time T _TLC , the amount of change (change amount per unit time) dx of the lateral displacement Xs, and the current lateral displacement X0 of the vehicle (18) As shown in the formula.
Xs = dx × T _TLC + X0 (18)

In this step S3, the lane departure determination time T _TLC defined in this way is set based on the control state by the ACC. FIG. 10 shows an example of the processing procedure of the setting process.
First, in step S11, it is determined whether or not the ACC is operating. For example, when the ACC main switch (start switch 23a) is ON, it is determined that the ACC is operating. In step S11, if the ACC is in operation, the process proceeds to step S12. If not, the process proceeds to step S14.

In step S14, it sets the ordinary lane departure determination time lane departure determination time _{T TLC T TLC} 0. Then, the process (step S3) shown in FIG. 10 ends.
In step S12, it is determined whether or not the inter-vehicle distance (any value of “long”, “medium”, and “short”) is set by the set inter-vehicle distance switch 23c. If the inter-vehicle distance is set with the set inter-vehicle distance switch 23c, the process proceeds to step S13. If the inter-vehicle distance is not set with the set inter-vehicle distance switch 23c, the process proceeds to step S15.

  Here, if the inter-vehicle distance is set by the set inter-vehicle distance switch 23c, the follow-up control is performed so that the set inter-vehicle distance is obtained in the ACC. Further, although the following distance control is set by the set inter-vehicle distance switch 23c and the follow-up control is performed, the follow-up control is intentionally set by the driver even when the follow-up control is canceled due to the loss of the preceding vehicle. Unless the inter-vehicle distance switch 23c is canceled, the inter-vehicle distance is set by the set inter-vehicle distance switch 23c.

In step S13, a lane departure determination time _TTLC is set based on the set inter-vehicle distance. Specifically, when the set inter-vehicle distance is “short”, the first lane departure determination time T _TLC 1 (> T _TLC 0) larger than the normal lane departure determination time T _TLC 0 is set as the lane departure determination time T _TLC . When the set inter-vehicle distance is “medium”, the second lane departure determination time T _TLC 2 (> T _TLC 1) larger than the first lane departure determination time T _TLC 1 is set as the lane departure determination time T _TLC. When the set inter-vehicle distance is “long”, the third lane departure determination time T _TLC 3 (> T _TLC 2) larger than the second lane departure determination time T _TLC 2 is set as the lane departure determination time T _TLC . Then, the process (step S3) shown in FIG. 10 ends.

In step S15, the first lane departure determination time T _TLC 1 corresponding to the set inter-vehicle distance of “short” is set as the lane departure determination time T _TLC . Then, the process (step S3) shown in FIG. 10 ends.
Subsequently, in step S4, a lane departure tendency is determined. Specifically, the processing procedure of this determination processing is as shown in FIG. FIG. 12 illustrates the definition of values used in this process.

First, in step S21, the estimated lateral displacement Xs is calculated from the equation (18) based on the lane departure determination time T _TLC set in step S3. Here, from the relationship of the equation (18), the estimated lateral displacement Xs increases as the lane departure determination time _TTLC increases, that is, as the set inter-vehicle distance increases.
Subsequently, in step S22, departure determination is performed. Specifically, comparing the estimated lateral displacement Xs with a predetermined departure-tendency threshold value X _L.

Here, departure-tendency threshold value X _L is generally the vehicle is a value that can be grasped to be in the lane departure tendency is obtained in experiments or the like. For example, the departure tendency determination threshold value _XL is a value indicating the position of the boundary line of the travel path, and is calculated by the following equation (19).
X _L = (D−H) / 2 (> 0) (19)
Here, D is the lane width and H is the width of the vehicle. The lane width D is obtained by processing the captured image by the imaging unit 13. Further, the vehicle position may be obtained from the navigation device 14 or the lane width D may be obtained from the map data of the navigation device 14.

In this step S22, when the estimated lateral displacement Xs is greater than or equal to the threshold X _L for determining the tendency to deviate (| Xs | ≧ X _L), determines that there is a lane departure tendency, the estimated lateral displacement Xs is for judging the departure tendency threshold If it is less than the value _{X L (| Xs | <X} L), it determines that there is no lane departure tendency.
Subsequently, in step S23, a departure determination flag is set. That is, when it is determined in step S22 that there is a lane departure tendency (| Xs | ≧ X _L ), the departure determination flag Fout is turned ON (Fout = ON). Further, in step S22, when it is determined that no lane departure tendency _{(| Xs | <X L)} , turns OFF the departure flag Fout (Fout = OFF).

By the process of step S22 and step S23, for example, the vehicle is going away from the center of the lane, when the estimated lateral displacement Xs is equal to or greater than the departure-tendency threshold value _{X L (| Xs | ≧ X} L), departure The determination flag Fout is turned on (Fout = ON). Further, the vehicle (host vehicle Fout = ON state) is gradually restored to the lane center side, when the estimated lateral displacement Xs becomes less than departure-tendency threshold value _{X L (| Xs | <X} L ), The departure determination flag Fout is turned off (Fout = OFF). For example, when there is a tendency to deviate from the lane, the departure determination flag Fout is changed from ON to OFF if braking control for preventing departure described later is performed or the driver himself performs an avoidance operation.

As described above, as the lane departure determination time _TTLC becomes longer, that is, as the set inter-vehicle distance becomes longer, the estimated lateral displacement Xs becomes larger, so it is easier to determine that there is a lane departure tendency.
Subsequently, in step S24, the departure direction Dout is determined based on the lateral displacement X. Specifically, when the vehicle is laterally displaced from the center of the lane to the left, the direction is set as the departure direction Dout (Dout = left), and when the vehicle is laterally displaced from the center of the lane to the right, the direction is changed to the departure direction Dout. (Dout = right).

As described above, the lane departure tendency is determined in step S4.
Subsequently, in step S5, the driver's intention to change lanes is determined. Specifically, the driver's intention to change the lane is determined as follows based on the direction switch signal and the steering angle δ obtained in step S1.
If the direction indicated by the direction switch signal (the blinker lighting side) is the same as the direction indicated by the departure direction Dout obtained in step S4, it is determined that the driver has intentionally changed the lane, and the departure determination flag Fout is changed to OFF (Fout = OFF). That is, it is changed to the determination result that there is no lane departure tendency.

When the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout obtained in step S4, the departure determination flag Fout is maintained and the departure determination flag Fout is kept ON. (Fout = ON). That is, the determination result that there is a tendency to depart from the lane is maintained.
When the direction indicating switch 20 is not operated, the driver's intention to change the lane is determined based on the steering angle δ. That is, when the driver is steering in the departure direction, the driver is conscious when both the steering angle δ and the change amount of the steering angle (change amount per unit time) Δδ are equal to or greater than the set value. And the departure determination flag Fout is changed to OFF (Fout = OFF).

The driver's intention may be determined based on the steering torque.
As described above, when the departure determination flag Fout is ON, when the driver has not intentionally changed the lane, the departure determination flag Fout is maintained ON.
Subsequently, in step S6, when the departure determination flag Fout is ON, a sound output or display output is performed as an alarm for preventing lane departure.

As will be described later, when the departure determination flag Fout is ON, the application of the yaw moment to the vehicle is started as the lane departure prevention control, so that the alarm is output at the same time. However, the alarm output timing is not limited to this, and may be earlier than, for example, the start timing of the yaw moment application.
Subsequently, in step S7, a target yaw moment Ms to be given to the host vehicle as lane departure prevention control is calculated.

Specifically, the target yaw moment Ms is calculated by the following equation (20) based on the estimated lateral displacement Xs obtained and lateral displacement limit distance X _L in the step S3.
Ms = Ks · (| Xs | −X _L ) (20)
Here, Ks is a yaw moment correction gain, and is set according to the vehicle speed V and the set inter-vehicle distance, for example. FIG. 13 shows an example of the characteristics of the yaw moment correction gain Ks. As shown in FIG. 13, when the host vehicle speed V is low, the yaw moment correction gain Ks becomes a certain small value. When the host vehicle speed V exceeds a certain value, the host vehicle speed V and the yaw moment correction gain Ks are proportional. When the vehicle speed V further increases, the yaw moment correction gain Ks becomes a certain large value. Furthermore, the yaw moment correction gain Ks decreases as the set inter-vehicle distance increases even for the same host vehicle V. For example, the value normally used as the yaw moment correction gain Ks is 1, and the yaw moment correction gain Ks decreases with a value less than 1 as the host vehicle speed V decreases or the set inter-vehicle distance increases.

The target yaw moment Ms is set to a larger value as the deviation from the lane (predetermined reference position) increases. The target yaw moment Ms increases as the yaw moment correction gain Ks increases, that is, as the vehicle speed V increases or the set inter-vehicle distance decreases.
The target yaw moment Ms is calculated when the departure determination flag Fout is ON, and the target yaw moment Ms is set to 0 when the departure determination flag Fout is OFF.

  FIG. 14 shows an example of a method for displaying the current set value of the yaw moment correction gain Ks. As shown in FIG. 14, an indicator D1 that indicates the state of the yaw moment correction gain Ks is provided in the display section D that displays the vehicle speed and the like. As the set inter-vehicle distance increases, that is, the yaw moment correction gain Ks decreases. As shown, the length of the indicator D1 is gradually increased as shown by the changes in (a), (b), and (c) of FIG. This indicator D1 may also be used to display the setting state of the set inter-vehicle distance, or may be provided separately from the display of the setting state of the set inter-vehicle distance.

Subsequently, in step S8, a target brake hydraulic pressure for each wheel is calculated. That is, the final braking fluid pressure is calculated based on the presence or absence of braking control for preventing departure. Specifically, it is calculated as follows.
When the departure determination flag Fout is OFF, that is, when the determination result that there is no lane departure tendency is obtained, as shown in the following expressions (21) and (22), the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) are set to the brake fluid pressures Pmf, Pmr.
Psfl = Psfr = Pmf (21)
Psrl = Psrr = Pmr (22)
Here, Pmf is the brake fluid pressure for the front wheels. Further, Pmr is the braking fluid pressure for the rear wheels, and is a value calculated based on the braking fluid pressure Pmf for the front wheels in consideration of the front-rear distribution.
At this time, the front wheel target braking fluid pressure difference ΔPsf and the rear wheel target braking fluid pressure difference ΔPsr are both set to zero.

When the departure determination flag Fout is ON, that is, when a determination result that there is a lane departure tendency is obtained, first, based on the target yaw moment Ms, the front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr. Is calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (23) to (26).
If | Ms | <Ms1, ΔPsf = 0 (23)
ΔPsr = 2 · Kbr · Ms / T (24)
| Ms | ≧ Ms1 ΔPsf = 2 · Kbf · (Ms−Ms1) / T (25)
ΔPsr = 2 · Kbr · Ms1 / T (26)
Here, Ms1 represents a setting threshold value. T represents a tread. This tread T is set to the same value before and after for simplicity. Kbf and Kbr are conversion coefficients for the front wheels and the rear wheels when the braking force is converted into the braking hydraulic pressure, and are determined by the brake specifications.

  Thus, the braking force applied to the wheels is distributed according to the magnitude of the target yaw moment Ms. When the target yaw moment Ms is less than the setting threshold value Ms1, the front wheel target braking fluid pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking fluid pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. In addition, when the target yaw moment Ms is equal to or larger than the setting threshold value Ms1, a predetermined value is given to each target braking hydraulic pressure difference ΔPsr, ΔPsr, and a braking force difference is generated between the front, rear, left and right wheels.

Then, using the target braking hydraulic pressure differences ΔPsf and ΔPsr calculated as described above and the target braking hydraulic pressures Pgf and Pgr for deceleration, the final target braking hydraulic pressure Psi (i = i = fl, fr, rl, rr) are calculated.
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (27)
Further, as shown in the equation (27), the brake operation by the driver, that is, the target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated in consideration of the brake fluid pressures Pmf, Pmr. is doing. Then, the braking / driving force control unit 8 uses the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) calculated for each wheel thus calculated as a braking fluid pressure command value to the braking fluid pressure control unit 7. Output.

With the processing as described above, the following series of operations are performed.
First, various data are read from each sensor or the like (step S1), and the vehicle speed V is calculated (step S2).
Subsequently, the lane departure determination time _TTLC is set based on the set inter-vehicle distance (step S3, FIG. 10).
That is, when the inter-vehicle distance is set, when the set inter-vehicle distance is “short”, the first lane departure determination time T _TLC 1 (> T _TLC 0) that is larger than the normal lane departure determination time T _TLC 0 Is set as the lane departure judgment time T _TLC and the set inter-vehicle distance is “medium”, the second lane departure judgment time T _TLC 2 (> T _TLC 1) larger than the first lane departure judgment time T _TLC 1 is set to the lane. When the departure determination time T _TLC is set and the set inter-vehicle distance is “long”, the third lane departure determination time T _TLC 3 (> T _TLC 2) larger than the second lane departure determination time T _TLC 2 is determined as the lane departure determination. Set to time T _TLC . That is, when the inter-vehicle distance is set, the lane departure determination time T _TLC is set to a larger value as the set inter-vehicle distance increases.

Although ACC is in operation, if the inter-vehicle distance is not set, set inter-vehicle distance is set to the first lane departure determination time T _{TLC 1} lane departure determination time T _TLC to be set if the "short" .
Subsequently, a lane departure tendency is determined based on the estimated lateral displacement Xs calculated by the lane departure determination time T _TLC set as described above (step S4). Here, when there is a lane departure tendency, the departure determination flag Fout is turned ON, and the departure direction Dout is further detected. When there is no lane departure tendency, the departure determination flag Fout is turned OFF (step S3). Even when the departure determination flag Fout is turned ON, the driver's intention to change the lane is determined. If the driver has an intention to change the lane, the departure determination flag Fout is changed to OFF, If there is no intention to change, the departure determination flag Fout is kept ON (step S5).

  When the departure determination flag Fout is ON, a warning is output (step S6). If the departure determination flag Fout is ON, the target yaw moment Ms to be given to the host vehicle as lane departure prevention control is calculated (step S7). Here, the target yaw moment Ms is corrected so as to decrease as the set inter-vehicle distance increases. Then, a braking force is generated on the wheels so that the calculated target yaw moment Ms is applied to the host vehicle (step S8). As a result, when there is a tendency to depart from the lane, the host vehicle avoids the departure by the yaw motion.

By the processing as described above, the following vehicle behavior is obtained according to the control state of the ACC.
(1) When the ACC main switch is turned on, but the inter-vehicle distance is not set by the set inter-vehicle distance switch 23c (the set / coast switch 23d or the resume / accelerate switch 23e is not turned on). , yaw set when setting the inter-vehicle distance is together with the first lane departure determination time set T _{TLC 1} in the case of "short" is set in lane departure determination time T _TLC, the set inter-vehicle distance "short" The target yaw moment Ms is calculated (corrected) by the moment correction gain Ks.

As a result, when the ACC is operating, it is easy to determine that there is a tendency to deviate from the lane, and when it is determined that there is a tendency to deviate from the lane, a yaw moment that is smaller than the yaw moment that is normally used is applied to the host vehicle. become.
At this time, it can be said that the state of the driver who is operating the ACC is more relaxed than the case where the ACC is not operating. In particular, the turning characteristics of the host vehicle can be suppressed by reducing the yaw moment. Therefore (because it takes more time to complete the departure prevention), the vehicle behavior characteristics match those of the driver.

(2) When the main switch of ACC is turned on and the inter-vehicle distance is set by the set inter-vehicle distance switch 23c (following traveling control is being performed) In this case, the lane departure judgment time T increases as the set inter-vehicle distance increases. _The target yaw moment Ms is calculated (corrected) by the yaw moment correction gain Ks that is set smaller as the _TLC is set larger and the set inter-vehicle distance is larger.
As a result, when the inter-vehicle distance is set during ACC, it becomes easier to determine that there is a tendency to deviate from the lane as the set inter-vehicle distance increases, and when it is determined that there is a tendency to deviate from the lane, the smaller the set inter-vehicle distance becomes, the smaller The yaw moment is applied to the vehicle.

  Further, with reference to FIG. 15, as shown in the order from FIG. 15A to FIG. 15D, as the set inter-vehicle distance is changed so as to increase the set inter-vehicle distance, the lane is closer to the center line. It is determined that there is a tendency to deviate (the control start timing becomes earlier), and at that time, the yaw moment to be given to the host vehicle as lane departure prevention control becomes smaller, that is, the turning characteristics of the host vehicle are further suppressed. Thus, the control characteristics of the vehicle behavior are changed.

  Here, as the set inter-vehicle distance increases, the inter-vehicle distance from the vehicle ahead increases and the driver's sense of security increases.Therefore, the driver's state is more relaxed as the set inter-vehicle distance increases. However, as shown in FIG. 15, as the set inter-vehicle distance increases, the turning characteristics are suppressed, so that such vehicle behavior characteristics match the driver's condition.

  Further, as the set inter-vehicle distance increases, the yaw moment is reduced while the control start timing (the yaw moment applying timing) is advanced. Thus, by making it easier to determine that there is a tendency to depart from the lane, a trade-off does not occur by reducing the yaw moment for the purpose of preventing lane departure.

  For example, according to the technique disclosed in Patent Document 2, when the set inter-vehicle distance is short, the inter-vehicle distance control gain is increased to make the vehicle behavior agile. When the set inter-vehicle distance is long, the inter-vehicle distance The control gain is reduced to slow down the vehicle behavior. Such a technique may be mounted on the vehicle of the above-described embodiment. Even if such a configuration is adopted, the driver's intention is to suppress the turning characteristics as the set inter-vehicle distance increases and to decrease the inter-vehicle distance control gain as the set inter-vehicle distance increases in the prior art. From the viewpoint of making the vehicle behavior consistent with

(3) Others For example, when the vehicle ahead is lost in ACC (when it is lost), the host vehicle travels at the set vehicle speed. In this case, the lane departure determination time T _TLC and the yaw moment correction gain Ks corresponding to the set inter-vehicle distance (the latest set inter-vehicle distance) set up to that point are set.
That is, even if the ACC loses sight of the vehicle ahead (lost), it is considered that the driver's relaxed state in the latest following state is maintained, so the vehicle behavior characteristic is maintained and the turning characteristic of the host vehicle is maintained. By suppressing the above, such a vehicle behavior characteristic matches that of the driver.
Further, it is conceivable that the driver cannot grasp the current set inter-vehicle distance or forgets due to the absence of the preceding vehicle. Even in this case, the driver can use the indicator D1 shown in FIG. The current yaw moment correction gain Ks, that is, the turning characteristics of the host vehicle can be known.

  Also, when the lane departure prevention control is operating (the vehicle condition is changing), the shift range operation (driver's driving operation condition), or the road shape (the surrounding environment condition of the vehicle) is changing. Even if an operation for changing the yaw moment correction gain Ks is performed, the yaw moment correction gain Ks is maintained at a value that is normally used (for example, 1), or the yaw moment correction gain Ks is already set based on the set inter-vehicle distance. If it is, the yaw moment correction gain Ks is maintained at a normally used value (for example, 1).

  For example, if the yaw moment correction gain Ks is changed from a normally used value (for example, 1) to another value (for example, a value less than 1) due to the operation of the ACC even during the lane departure prevention control, the vehicle behavior becomes unstable. This will make the driver feel uncomfortable. On the other hand, when the lane departure prevention control is being performed, such a situation can be prevented by maintaining the yaw moment correction gain Ks at a normally used value.

In addition, when the driver frequently operates the shift range, it is difficult to say that the driver is relaxed even if the ACC is operating. For this reason, when there is a change in the shift range operation by the driver, the yaw moment correction gain Ks is maintained at a normally used value so that the vehicle behavior characteristic matches the driver's intention.
Similarly, when the road shape varies, it is difficult to say that the driver is relaxed. For this reason, when there is a change in the road shape, the yaw moment correction gain Ks is maintained at a normally used value so that the vehicle behavior characteristics match the driver's intention.

The embodiments of the present invention have been described above. However, the present invention is not limited to being realized as the embodiment.
That is, in the embodiment, the case where the vehicle behavior control device that controls the vehicle behavior of the host vehicle according to the traveling state of the host vehicle is the lane departure prevention device has been described. However, it is not limited to this. In other words, other vehicle behavior control devices that control the vehicle behavior according to the traveling state of the host vehicle, such as controlling the braking force of each wheel, can suppress the side slip of the vehicle and maintain a stable traveling posture. The present invention can also be applied to a VDC (Vehicle Dynamics Control) and a lane keeping system that applies a steering reaction force so as to travel in the center of the lane.

  In the embodiment, the case where the inter-vehicle distance is set stepwise such that the set inter-vehicle distance is “long”, “medium”, or “short” has been described. However, it is not limited to this. For example, the inter-vehicle distance may be set linearly. In this case, the rear wheel steering control gain is also set linearly corresponding to the inter-vehicle distance set in such a manner.

  In the embodiment, as the set inter-vehicle distance increases, the control start timing of the lane departure prevention control is advanced and the yaw moment applied to the host vehicle is reduced. This is because, for example, in order to reliably prevent lane departure even when the yaw moment applied to the host vehicle is reduced for the purpose of suppressing lane departure prevention control as the set inter-vehicle distance increases. As a result, the control start timing is advanced. However, for the purpose of suppressing the lane departure prevention control as the set inter-vehicle distance increases, the control start timing of the lane departure prevention control may be delayed as the set inter-vehicle distance increases.

For example, if FIG. 10 used for setting the lane departure determination time in step S3 is used, the following is obtained. For example, in step S14, the normal lane departure determination time T _TLC 0 is set as the lane departure determination time T _TLC in the same manner as described above. However, in step S13, when the set inter-vehicle distance is “short”, the first lane departure determination time T _TLC 1 (<T _TLC 0) smaller than the normal lane departure determination time T _TLC 0 is used as the lane departure determination time T _TLC. And the second lane departure judgment time T _TLC 2 (<T _TLC 1) smaller than the first lane departure judgment time T _TLC 1 is set as the lane departure judgment time T _TLC . When the set inter-vehicle distance is “long”, the third lane departure determination time T _TLC 3 (<T _TLC 2) smaller than the second lane departure determination time T _TLC 2 is set as the lane departure determination time T _TLC . In step S15, the first lane departure determination time T _TLC 1 (<T _TLC 0) corresponding to the set inter-vehicle distance of “short” is set as the lane departure determination time T _TLC .

Thus, as the set inter-vehicle distance increases, the control start timing of the lane departure prevention control is delayed, so that the vehicle behavior by the lane departure prevention control is relaxed, for example, because the lane departure prevention control does not frequently operate. The vehicle behavior matches the driver's intention to be in the state.
As described above, when the control start timing is delayed as the set inter-vehicle distance increases, it is preferable to increase the yaw moment applied to the host vehicle as the lane departure prevention control as the set inter-vehicle distance increases. Thereby, for the purpose of preventing lane departure, the control start timing of the lane departure prevention control (the yaw moment applying timing) is delayed so that no trade-off occurs.

  Further, in the above embodiment, the yaw moment is given to the vehicle by giving a braking force difference to the left and right wheels. However, the present invention is not limited to this, for example, a steering actuator for driving a steering is provided, and this steering actuator Alternatively, the yaw moment may be applied to the host vehicle by applying a driving force to the vehicle. Moreover, the structure which gives a yaw moment to the own vehicle by combining steering and braking may be sufficient. Furthermore, instead of the braking force difference between the left and right wheels, a configuration in which the yaw moment is given to the host vehicle by changing the driving force distribution to the left and right wheels to give the driving force difference may be adopted.

  In the description of the embodiment, the calculation of the target yaw moment Ms using the yaw moment correction gain Ks in step S7 by the braking / driving force control unit 8 is based on the set inter-vehicle distance from the preceding vehicle set by the driver. Thus, the control characteristic changing means for changing the control characteristic of the vehicle behavior control device so as to match the intention of the driver is realized.

It is a figure which shows an example of the vehicle carrying the traveling control apparatus of the vehicle of this invention. It is a block diagram which shows the structure for implementing ACC, which is a structure of the control unit of the vehicle travel control device. It is a block diagram for demonstrating the ranging signal process part of the said control unit. It is a block diagram for demonstrating the relative speed calculating part of the said control unit. It is a block diagram for demonstrating the inter-vehicle distance control part of the said control unit. It is a block diagram for demonstrating the inter-vehicle distance control part of the said control unit. It is a block diagram for demonstrating the target inter-vehicle distance setting part of the said control unit. It is a perspective view which shows the structure of the manual switch of ACC. It is a flowchart which shows the process sequence of lane departure prevention control by the said control unit. It is a flowchart which shows the process sequence of the setting of the lane departure judgment time by the said control unit. It is a flowchart which shows the processing content of determination of the lane departure tendency by the said control unit. It is a diagram used for explanation of the estimated lateral displacement Xs and deviation judgment threshold value X _L. It is a characteristic view showing the relationship between the vehicle speed V and the set inter-vehicle distance and the yaw moment correction gain Ks. It is a figure which shows an example of the display method of the present setting value of a yaw moment correction gain. It is a figure which shows the vehicle behavior according to each setting inter-vehicle distance at the time of lane departure prevention control.

Explanation of symbols

5FL to 5RR Wheel 6FL to 6RR Wheel cylinder 7 Braking fluid pressure control circuit 8 Braking / driving force control unit 9 Engine 12 Driving torque control unit 13 Imaging unit 15 Navigation device 16 Radar 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 21 Steering wheels 22FL to 22RR Wheel speed sensor 23 Manual switch 23c Set inter-vehicle distance switch 31 Vehicle speed signal processing unit 32 Image processing unit 33 Vehicle speed control unit 34 Distance signal processing unit 40 Travel control unit

Claims (8)

In a vehicle travel control device equipped with a vehicle speed control device that controls a vehicle speed so as to follow a preceding vehicle, and a vehicle behavior control device that controls the vehicle behavior of the host vehicle according to the travel state of the host vehicle,
An inter-vehicle distance setting means for a driver to set an inter-vehicle distance from the preceding vehicle during vehicle speed control by the vehicle speed control device;
Control characteristic changing means for changing the control characteristic of the vehicle behavior control device to match the intention of the driver based on the set inter-vehicle distance set with the preceding vehicle set by the driver;
The vehicle behavior control device is a lane departure prevention device that performs lane departure prevention control for preventing the own vehicle from departing from the traveling lane when the own vehicle tends to deviate from the traveling lane,
The control characteristic changing means changes the control characteristic of the lane departure prevention control so that the vehicle behavior becomes slower as the set inter-vehicle distance becomes longer and the vehicle behavior becomes more agile as the set inter-vehicle distance becomes shorter. A travel control device for a vehicle. The vehicle speed control device sets a vehicle speed control characteristic based on an inter-vehicle distance, and the control characteristic changing means matches the control characteristic of the vehicle behavior control device with the vehicle speed control characteristic. travel control device for a vehicle according to 1. The vehicle speed control device controls the vehicle speed so as to become a set vehicle speed when losing sight of a preceding vehicle, and the control characteristic changing means, when losing sight of the preceding vehicle, based on the latest set inter-vehicle distance, running control apparatus for a vehicle according to claim 1 or 2, characterized in that to change the control characteristic of the vehicle behavior control device. The control characteristics changing unit, the set inter-vehicle distance setting value becomes larger, the travel control device for a vehicle according to claim 1, characterized in that the lane departure prevention control changes its control amount so as to suppress . The lane departure prevention control provides a yaw moment to the host vehicle when the departure tendency tends to prevent the host vehicle from deviating from the traveling lane, and the control characteristic changing means includes the set inter-vehicle distance 5. The vehicle travel control device according to claim 4 , wherein the yaw moment is decreased or the operation start timing of the lane departure prevention control is delayed as the set value of the distance increases. 6. The vehicle according to claim 5, wherein the control characteristic changing unit increases the yaw moment when the yaw moment is reduced, when the operation start timing is advanced or when the operation start timing is delayed. Travel control device. The inter-vehicle distance setting means is capable of setting the set inter-vehicle distance stepwise, and the control characteristic changing means is a control amount of the lane departure prevention control based on the set inter-vehicle distance at the set stage. running control apparatus for a vehicle according to any one of claims 4 to 6, characterized in that to change the. The control characteristic changing means changes a control amount of the lane departure prevention control based on at least one of a driving operation state by the driver, a host vehicle state, and a surrounding environment state of the host vehicle. The vehicle travel control device according to any one of claims 4 to 7 .

Images