JP2006327356A - Travelling controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To design cooperation between vehicle speed control and lane departure preventing control. <P>SOLUTION: When an estimated lateral displacement Xs is above a threshold for brake control determination X<SB>L</SB>2 (in the case of tendency of lane deviation), the preventing control is operated prior to an acceleration control (vehicle speed control) by ACC (step S32 to step S35). On the other hand, when the displacement Xs is above a prescribed value X<SB>L</SB>3 (X<SB>L</SB>1>¾Xs¾≥X<SB>L</SB>3), namely, just before it is determined that the vehicle shows the tendency of the lane departure, the the acceleration control by the ACC is suppressed (step S36, step S37). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  A lane that performs lane departure prevention control that prevents the own vehicle from deviating from the traveling lane based on a vehicle speed control device that controls the traveling of the own vehicle and a determination result of the lane departure obtained from the state of the own vehicle with respect to the traveling lane A travel control device for a vehicle equipped with a departure prevention device.

Conventionally, there has been proposed a technique for suppressing the vehicle speed by a vehicle speed control device when it is determined that the host vehicle may deviate from the traveling lane (see, for example, Patent Document 1).
JP 2003-327011 A

In the conventional technique, unless it is determined that the host vehicle may deviate from the traveling lane, acceleration control by the vehicle speed control device is performed as usual. That is, even if it is predicted that the possibility of departure is predicted immediately after the acceleration control, the acceleration control is performed. This acceleration control also prompts (accelerates) determination of possibility of departure. In addition, when performing the prevention control by decelerating or giving a yaw moment after the possibility of departure is determined, the departure prevention control is performed immediately after the host vehicle is accelerated, and the vehicle behavior is greatly increased. Changes will also occur. Such a large change in vehicle behavior makes the driver feel uncomfortable, thereby making the driver feel bothered by vehicle speed control and lane departure prevention control.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle travel control device that coordinates vehicle speed control and lane departure prevention control.

  The vehicle travel control apparatus according to claim 1 determines that the vehicle has a tendency to deviate from the traveling lane when the degree of the tendency of the own vehicle to deviate from the traveling lane is equal to or greater than a predetermined threshold, and has priority over the vehicle speed control. Then, lane departure prevention control is performed, and when it is determined that there is no departure tendency, acceleration by vehicle speed control is suppressed based on the degree of departure tendency.

  According to the vehicle travel control device of the first aspect, since acceleration is suppressed according to the degree of departure of the host vehicle, acceleration can be suppressed before the lane departure prevention control is performed. Can be prevented, and the vehicle behavior can be prevented from changing significantly.

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. Normally, the brake fluid pressure boosted by the master cylinder 3 according to the amount of depression of the brake pedal 1 by the driver is shown. 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, a lane (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, when there is no white line (lane marker) on the road to make it possible to recognize the driving lane, the information on road shape and surrounding environment obtained by image processing and various sensors can be used to determine 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 cliffs, the asphalt portion of the runway is determined as the travel lane. If there are guardrails, curbs, etc., the driving lane is determined in consideration of the information.

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.

The processing contents of ACC are 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 preceding 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 the distance L between the vehicle and the vehicle speed Vsp calculated by the vehicle speed signal processing unit 31 and a 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 ^* is set based on the own vehicle speed Vsp and the relative speed ΔV calculated by the relative speed calculation unit 41 or the inter-vehicle distance setting value Ls set by the driver by an operation with a manual switch (not shown), 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, and the relative speed ΔV calculated by the relative speed calculation unit 41 and the inter-vehicle distance calculated by the ranging signal processing unit 34 based on the running environment information from the distance L and the navigation device 14, to match the inter-vehicle distance L to the target inter-vehicle distance setting section 42 target inter-vehicle distance calculated at L ^* And a distance control unit 43 for calculating a target vehicle speed V ^*.

Then, the vehicle speed control unit 33 calculates the target acceleration / deceleration speed V ′ 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. When ′ is a negative value, the braking fluid pressure control unit 7 is controlled to generate a braking force so that the target acceleration / deceleration V ′ can be realized. Conversely, the target acceleration / deceleration V ′ is a positive value. In this case, the drive torque control unit 12 and an automatic transmission (not shown) are controlled so as to realize the target acceleration / deceleration V ′.

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 FIG. 5, 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 as shown in the following equation (2). And ΔV ^* , which is the sum of the relative speed ΔV and the control 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 ^* .
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 the vehicle speed Vt of the preceding vehicle is constant, 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 in vehicle speed between 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 the function of the vehicle speed Vt of the preceding vehicle from the viewpoint of not affecting the convergence of 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 by 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 relative speed detection 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 a manual switch (not shown), the inter-vehicle distance set value Ls is set to the target inter-vehicle distance set value Ls. It is set as the inter-vehicle distance L ^* .

There is also a vehicle speed setting switch that allows the driver to set the vehicle speed. As a result, when the preceding vehicle disappears from the state in which the host vehicle is following the preceding vehicle (lost), the target vehicle speed V ^* is set to the set vehicle speed set by the vehicle speed setting switch. The vehicle is accelerated to reach the set vehicle speed (target vehicle speed).
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 (X0), 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.
In addition, you may use the own vehicle speed which the vehicle speed signal process part 31 calculated for ACC.

Subsequently, in step S3, a lane departure tendency is determined. Specifically, the processing procedure of this determination processing is as shown in FIG. FIG. 10 illustrates the definition of values used in this process.
First, in step S21, an estimated lateral displacement Xs of the vehicle center of gravity lateral position after a predetermined time T is calculated. Specifically, using the yaw angle φ obtained in step S1, the travel lane curvature β and the lateral displacement X0 of the current vehicle, and the vehicle speed V obtained in step S2, the estimated lateral displacement is given by the following equation (18). Xs is calculated.
Xs = Tt · V · (φ + Tt · V · β) + X0 (18)

Here, Tt is the vehicle head time for calculating the forward gaze distance, and when this vehicle head time Tt is multiplied by the own vehicle speed V, it becomes the front gaze distance. That is, the estimated lateral displacement from the center of the traveling lane after the vehicle head time Tt becomes the estimated lateral displacement Xs in the future.
For example, according to the equation (18), the estimated lateral displacement Xs increases as the host vehicle V increases, and the estimated lateral displacement Xs increases as the yaw angle φ increases.
Subsequently, in step S22, departure determination is performed. Specifically, the estimated lateral displacement Xs is compared with a predetermined departure tendency determination threshold value X _L 1.

Here, the threshold value _{L L1} for determining the departure tendency is a value that can be generally grasped as indicating that the vehicle is in a lane departure tendency, and is obtained through experiments or the like. For example, the departure tendency determination threshold value X _L 1 is a value indicating the position of the boundary line of the travel path, and is calculated by the following equation (19).
X _L 1 = (D−H) / 2 (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 departure tendency determination threshold value X _L 1 (| Xs | ≧ X _L 1), it is determined that there is a lane departure tendency, and the estimated lateral displacement Xs is used for departure tendency determination. If it is less than the threshold value X _L 1 (| Xs | <X _L 1), it is determined that there is no lane departure tendency.
As described above, the estimated lateral displacement Xs increases as the host vehicle V and the yaw angle | φ | increase. Therefore, as the host vehicle V and the yaw angle | φ | increase, it is easier to determine that there is a tendency to depart from the lane.

Subsequently, in step S23, a departure determination flag Fout is set. That is, if it is determined in step S22 that there is a tendency to depart from the lane (| Xs | ≧ X _L 1), 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 1} ), turns OFF the departure flag Fout (Fout = OFF).

By the processing of step S22 and step S23, for example, when the host vehicle moves away from the center of the lane and the estimated lateral displacement Xs becomes equal to or greater than the departure tendency determination threshold value X _L 1 (| Xs | ≧ X _L 1) The departure determination flag Fout is turned on (Fout = ON). Further, when the host vehicle (the host vehicle in the state of Fout = ON) returns to the lane center side and the estimated lateral displacement Xs becomes less than the departure tendency determination threshold value X _L 1 (| Xs | <X _L 1), 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.

  Here, in this embodiment, the possibility of deviation is determined by comparing the estimated lateral displacement Xs after a predetermined time Tt with a predetermined threshold. However, the present invention is not limited to this, and the (18 ) Substituting Xs = ± D / 2 in the equation, calculating the predetermined time Tt as the time until the lane departure, and determining the possibility of departure by comparing the predetermined time Tt with a predetermined threshold. good. For example, if Tt ≦ 1 [sec], it is determined that there is a possibility of lane departure. Here, the time until the estimated lateral displacement or lane departure corresponds to the “departure tendency degree” described in the claims.

Subsequently, in step S24, the departure direction Dout is determined based on the lateral displacement X0. 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 S3.

Subsequently, in step S4, the driver's intention to change lanes is determined. Specifically, based on the direction switch signal and the steering angle δ obtained in step S1, the driver's intention to change lanes is determined as follows.
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 S3, 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.

If 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 S3, 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 lanes 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).

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 S5, a control method for preventing lane departure is determined. The processing procedure of this control method is specifically as shown in FIG.
First, in step S31, it is determined whether or not the departure determination flag Fout is ON. Here, when the departure flag Fout is _{ON (| Xs | ≧ X L} 1), as there is a lane departure tendency, the process proceeds to step S32, when the departure flag Fout is not _{ON (| Xs | <X L} 1) Since there is no lane departure tendency, the process proceeds to step S36.

In step S32, acceleration / deceleration control by ACC is prohibited, and in subsequent step S33, an alarm for preventing lane departure is issued. The alarm is, for example, sound output or display output.
Subsequently, in Step S34, the estimated lateral displacement Xs is whether greater braking control determining threshold value X _{L 2} or more than the departure-tendency threshold value X _{L 1,} i.e. whether further advanced lane departure tendency not Determine whether. If the estimated lateral displacement Xs is equal to or greater than the braking control determination threshold value X _L 2 (| Xs | ≧ X _L 2), the process proceeds to step S35, where the estimated lateral displacement Xs is the braking control determination threshold value _XL. If it is less than _{2 (| Xs | <X L} 2), and ends the processing of the Figure 11 (step S5).

  In step S35, control (hereinafter referred to as lane departure prevention yaw control) for applying a yaw moment to the vehicle in order to prevent lane departure, which will be described later, is implemented (along with specific lane departure prevention yaw control). Is determined to execute control for decelerating the vehicle to prevent lane departure (hereinafter referred to as lane departure prevention deceleration control) immediately before the departure prevention yaw control is performed. Then, the process of FIG. 11 (step S5) is terminated.

Under the situation where it is determined that there is a tendency to depart from the lane by the processing of step S31 to step S35, the lane departure prevention control is operated with priority over the acceleration control (vehicle speed control) by ACC.
On the other hand, the departure flag Fout is OFF when _{(| Xs | <X L 1} ) At step S36 proceeds to the estimated lateral displacement Xs is departure-tendency threshold value _{X L} 1 small predetermined value _{X L} 3 or more than In the case (X _L 1> | Xs | ≧ X _L 3), that is, in a situation where it is determined that there is a tendency to deviate from the lane (immediately before it is determined that there is a tendency to deviate from the lane), the process proceeds to step S37. When the displacement Xs is less than the predetermined value X _L 3 (| Xs | <X _L 3), the processing in FIG. 11 (step S5) is terminated.

In step S37, acceleration by ACC is permitted, but the acceleration is suppressed.
For example, when the host vehicle is accelerated at an acceleration (target acceleration) V ′ in order to drive the host vehicle at the target vehicle speed V ^* in ACC, finally, the acceleration V ′ and the coefficient α (<1) The target vehicle speed V ^* is set so as to realize the multiplication value (V ′ · α). That is, the acceleration of the host vehicle is suppressed by adjusting the coefficient α.

Here, as shown in FIG. 12, the coefficient α (<1) is a value of 1 until the estimated lateral displacement Xs reaches a predetermined value X _L 3, and a threshold for determining a deviation tendency from the predetermined value X _L 3. in between the values X _{L 1,} larger the estimated lateral displacement Xs becomes a small value. As a result, until the estimated lateral displacement Xs reaches the predetermined value X _L 3, for example, near the center of the traveling lane (near the center in the lateral direction), the ACC accelerates at a normal acceleration, and the estimated lateral displacement Xs is predetermined. between the values X _{L 3} departure-tendency threshold value X _{L 1,} i.e. the by likely region determined that there is a lane departure tendency, but accelerated by ACC, the acceleration is suppressed, a large estimated lateral displacement Xs The degree of suppression increases.

Subsequently, in step S6, a target yaw moment Ms to be given to the 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 the lateral displacement limit distance X _{L 1} in the step S3.
Ms = K1 · K2 · (| Xs | −X _L 1) (20)
Here, K1 is a constant determined from vehicle specifications, and K2 is a gain that varies according to the vehicle speed V. FIG. 13 shows an example of the gain K2. As shown in FIG. 13, for example, the gain K2 becomes a small value in the low speed range, and becomes proportional to the vehicle speed V when the vehicle speed V reaches a certain value, and then becomes a constant value with a large value when reaching a certain vehicle speed V thereafter. . Thus, the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _{L 1} is, the target yaw moment Ms becomes larger.

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.
It is also possible to calculate the target yaw moment Ms on the basis of the braking control determining threshold value X _{L 2.} That is, in the equation (20), the target yaw moment Ms is calculated by replacing the lateral displacement limit distance X _L 1 with the braking control determination threshold value X _L 2.

Subsequently, in step S7, a deceleration for decelerating the vehicle as lane departure prevention control is calculated. That is, the braking force applied to the left and right wheels for the purpose of decelerating the host vehicle is calculated. Here, the target braking fluid pressures Pgf and Pgr that give such braking force to both the left and right wheels are calculated. The target braking hydraulic pressure Pgf for the front wheels is calculated by the following equation (21).
Pgf = Kgv · V + Kgx · dx (21)
Here, Kgv and Kgx are conversion coefficients that are set based on the vehicle speed V and the lateral change amount dx, respectively, for converting the braking force into the braking hydraulic pressure. FIG. 14 shows an example of the conversion coefficients Kgv and Kgx. As shown in FIG. 14, for example, the conversion coefficients Kgv and Kgx become large values in the low speed range, and when the vehicle speed V reaches a certain value, it decreases as the vehicle speed V increases, and then reaches a certain vehicle speed V. It becomes a constant value.

Then, based on the target braking hydraulic pressure Pgf for the front wheels, the target braking hydraulic pressure Pgr for the rear wheels considering the front-rear distribution is calculated.
As described above, in step S7, deceleration for preventing departure (specifically, target brake hydraulic pressures Pgf and Pgr) is obtained.
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.

(1) When the departure determination flag Fout is OFF (Fout = OFF), that is, when the determination result that there is no lane departure tendency is obtained, as shown in the following equations (22) and (23), The target brake fluid pressure Psi (i = fl, fr, rl, rr) is set to the brake fluid pressure Pmf, Pmr.
Psfl = Psfr = Pmf (22)
Psrl = Psrr = Pmr (23)
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 hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr are both set to zero.

(2) When the departure determination flag Fout is ON (Fout = 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 A 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 (24) to (27).
If | Ms | <Ms1, ΔPsf = 0 (24)
ΔPsr = 2 · Kbr · Ms / T (25)
| Ms | ≧ Ms1 ΔPsf = 2 · Kbf · (Ms−Ms1) / T (26)
ΔPsr = 2 · Kbr · Ms1 / T (27)
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, the final target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated using the target brake fluid pressure differences ΔPsf, ΔPsr calculated as described above and the target brake fluid pressures Pgf, Pgr for deceleration. ) Is calculated.
That is, when it is determined in step S5 that the lane departure prevention yaw control is to be performed as the control method, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (28)

If it is determined in step S5 that the lane departure prevention yaw control and the lane departure prevention deceleration control are performed as the control method, the target braking hydraulic pressure Psi of each wheel is expressed by the following equation (29). (I = fl, fr, rl, rr) is calculated.
Psfl = Pmf + Pgf / 2
Psfr = Pmf + ΔPsf + Pgf / 2
Psrl = Pmr + Pgr / 2
Psrr = Pmr + ΔPsr + Pgr / 2
... (29)
Further, as shown in the equations (28) and (29), the deceleration operation by the driver, that is, the target brake fluid pressure Psi (i = fl, fr, rl) of each wheel in consideration of the brake fluid pressures Pmf, Pmr. , Rr).

The above is the calculation processing by the braking / driving force control unit 8. The braking / driving force control unit 8 outputs the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel calculated in step S8 to the braking fluid pressure control unit 7 as a braking fluid pressure command value. .
The above is the processing content of the lane departure prevention control.
The operation as described above is roughly as follows.

First, various data are read from each sensor, controller, and control unit (step S1). Subsequently, the vehicle speed V is calculated (step S2).
Subsequently, the estimated lateral displacement Xs is calculated, and the departure determination flag Fout is set based on the comparison result between the estimated lateral displacement Xs and the departure tendency determination threshold value X _L 1, and based on the lateral displacement X0. The departure direction Dout is determined (step S3). Further, the driver's intention to change the lane is determined based on the deviation direction Dout thus obtained and the direction indicated by the direction switch signal (the blinker lighting side) (step S4).

Subsequently, a control method for preventing lane departure is determined based on the departure determination flag Fout (step S5). That is, when the departure determination flag Fout is ON, the acceleration / deceleration control by ACC is stopped (step S32), a warning for preventing lane departure is issued (step S33), and when the departure tendency further advances, In order to prevent lane departure, it is determined to execute lane departure prevention yaw control or lane departure prevention deceleration control (step S35).
On the other hand, when the departure determination flag Fout is OFF, the acceleration control by the ACC is permitted while the acceleration is suppressed according to the estimated lateral displacement Xs in a situation where it is likely that there is a lane departure tendency. (Step S37).

Then, the target yaw moment Ms and the deceleration for preventing the lane departure for performing the lane departure prevention yaw control and the lane departure prevention deceleration control are calculated (steps S6 and S7), and it is determined that the vehicle is departing from the lane. (Fout = ON), the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel that realizes such a target yaw moment Ms and deceleration for preventing lane departure is calculated. The calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) is output to the brake fluid pressure controller 7 as a brake fluid pressure command value (step S8).
The braking fluid pressure control unit 7 individually controls the braking fluid pressures of the wheel cylinders 6FL to 6RR based on the braking fluid pressure command value. Thereby, when the own vehicle has a tendency to deviate from the lane, the own vehicle shows the turning behavior and the deceleration behavior.

Next, the effect in this embodiment is demonstrated.
As described above, the acceleration of the host vehicle for traveling at the target vehicle speed is suppressed by ACC immediately before it is determined that there is a lane departure tendency based on the determination result of the departure tendency obtained from the state of the host vehicle with respect to the traveling lane. In addition, when it is determined that there is a lane departure tendency based on the determination result, the lane departure prevention control is operated with priority over the ACC vehicle speed control. Thereby, even if the lane departure prevention control is activated during the vehicle speed control by the ACC, it is possible to prevent the vehicle behavior from changing greatly.
That is, as described above, the acceleration of the host vehicle for traveling at the target vehicle speed by the vehicle speed control is suppressed based on the determination result of the departure tendency obtained from the state of the host vehicle with respect to the traveling lane.

Specifically, under a situation where it is determined that there is a lane departure tendency based on the comparison result between the estimated lateral displacement Xs, the departure tendency determination threshold value X _L 1 and the predetermined value X _L 3 (X _L 1> | Xs | ≧ X _L 3), the acceleration of the host vehicle for traveling at the target vehicle speed by ACC is suppressed according to the difference between the estimated lateral displacement Xs and the threshold value for deviation tendency determination X _L 1 That is, the greater the difference, the smaller the suppression degree, and the smaller the difference, the greater the suppression degree. As a result, even if the vehicle behavior changes from the acceleration state due to ACC to the behavior for preventing lane departure, the vehicle behavior due to ACC and the vehicle behavior for preventing lane departure are smoothly connected. Is prevented from changing drastically.

Here, the effect will be described with reference to FIGS. 15 and 16.
As shown in FIG. 15B, when the host vehicle 100 and the preceding vehicle 101 travel along a curve and the host vehicle 100 follows the preceding vehicle 101 in ACC, as shown in FIG. When the preceding vehicle 101 changes lanes, the ACC of the host vehicle 100 loses (lost) the preceding vehicle 101 that is the subject of tracking. In this case, when the set vehicle speed is set in advance, the host vehicle 100 is accelerated to the set vehicle speed.

Here, as shown in FIG. 16, the estimated lateral displacement Xs of the forward gazing point, which is a parameter during the lane departure prevention control in the own vehicle 100, is still the departure tendency determination threshold value X _L 1 (more accurately, the braking control determination If the vehicle threshold value _XL2 ) is not reached, i.e., it is not determined that there is a tendency to deviate from the lane, the estimated lateral displacement is caused by the host vehicle 100 accelerating due to the loss. Xs reaches the departure tendency determination threshold value X _L 1 (more precisely, the braking control determination threshold value X _L 2) in a short time.

However, in this case, immediately after acceleration by ACC, yaw moment is applied to the host vehicle by the lane departure prevention control, the vehicle behavior changes greatly, and the change in the vehicle behavior gives the driver a sense of incongruity.
Here, in order to prevent this, when it is determined that there is a tendency to depart from the lane, acceleration is suppressed, and the degree of suppression of acceleration is determined according to the lateral estimated displacement Xs. As a result, the function by the ACC is exhibited as much as possible, and the convenience of the driver by the ACC is ensured as much as possible. However, after acceleration by the ACC, the yaw moment is given to the host vehicle by the lane departure prevention control. It is possible to eliminate the driver's uncomfortable feeling.

  In particular, as lane departure prevention control, when yaw moment is applied to the host vehicle by braking control (difference in braking force between left and right wheels), after acceleration by ACC as described above, deceleration is performed by lane departure prevention control braking control. This will increase the uncomfortable feeling given to the driver. Therefore, it can be said that it is more effective to apply the present invention to the lane departure prevention control in which the yaw moment is applied to the host vehicle by the braking control (the braking force difference between the left and right wheels).

The embodiment of the present invention has been described above. However, the present invention is not limited to being realized as the embodiment.
That is, in the above embodiment, acceleration in ACC control (inter-vehicle distance control when a preceding vehicle is detected, constant speed control when a preceding vehicle is not detected) is suppressed, but the present invention is not limited to this. In addition, the present invention can be applied only to constant speed control that travels at a constant speed at a set vehicle speed.

In FIG. 12, a warning is issued when the estimated lateral displacement Xs becomes equal to or greater than the departure tendency determination threshold value X _L 1, and when the estimated lateral displacement Xs becomes equal to or greater than the braking control determination threshold value X _L 2. Although the control (deceleration prevention deceleration control) is performed, the present invention is not limited to this. For example, the departure prevention yaw control (departure prevention deceleration control) becomes greater than or equal to the departure tendency determination threshold value X _L 1. ) May be performed. At this time, the threshold value for issuing an alarm may be set between a predetermined value X _L 3 or more and a deviation tendency determination threshold value X _L 1 or less.

  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, the configuration may be such that 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 instead of the braking force difference between the left and right wheels.

  Moreover, in the said embodiment, the brake structure is based on the brake structure using fluid pressure. However, it goes without saying that the present invention is not limited to this. For example, an electric friction brake that presses the friction material against the rotating body of the wheel side member by an electric actuator, a regenerative brake that generates an electric braking action, or a power generation brake may be used. Also, an engine brake that performs braking control by changing the valve timing of the engine, a speed change brake that acts like an engine brake by changing the speed ratio, or an air brake may be used.

In the above embodiment, when the departure determination flag Fout is ON, that is, when there is a lane departure tendency (| Xs | ≧ X _L 1), a warning is output, and then the lane departure tendency further proceeds (| Xs | ≧ X _L 2) The case where the lane departure prevention control such as the lane departure prevention yaw control or the lane departure prevention deceleration control is performed has been described. However, it is not limited to this. For example, when there is a lane departure tendency (| Xs | ≧ X _L 1), the lane departure prevention control may be performed simultaneously with the alarm output, or when it is determined that there is a lane departure tendency (for example, | Xs | ≧ X _L 3) If a warning is output and then there is a tendency to depart from the lane (| Xs | ≧ X _L 1), lane departure prevention control may be performed. Thereby, the effect similar to the effect in the said embodiment can be acquired.

In the embodiment, the case where the estimated lateral displacement Xs is calculated as a value for determining lane departure has been described. However, the present invention is not limited to this. For example, the deviation predicted time Tout is calculated by the following equation (30) using dx as the change amount of the lateral displacement X (change amount per unit time), L as the lane width, and the lateral displacement X.
Tout = (L / 2−X) / dx (30)
In this case, when the estimated departure time Tout reaches the departure tendency determination threshold Ts, it is determined that there is a lane departure tendency, and the departure determination flag Fout is turned ON. A warning is output at the timing when the predicted departure time Tout becomes the threshold value Ts for determining the departure tendency, and further, when the predicted lane departure tendency progresses, for example, when the predicted departure time Tout becomes 0, lane departure prevention is performed. Implement yaw control and deceleration control for lane departure prevention.

  On the other hand, ACC is also controlled based on the estimated departure time Tout. That is, even when the departure determination flag Fout is OFF (Tout> Ts), the departure predicted time Tout is within a predetermined range with a value Ts1 that is larger than the departure tendency determination threshold Ts (Ts1> Tout). > Ts), that is, in a situation where it is determined that there is a tendency to deviate from the lane, the addition / subtraction control by the ACC is permitted while the addition / subtraction is suppressed.

Further, the target yaw moment Ms may be obtained by other methods. For example, as shown in the following equation (31), the target yaw moment Ms may be calculated based on the yaw angle φ, the lateral displacement X, and the travel lane curvature β.
Ms = K3 · φ + K4 · X + K5 · β (31)
Here, K3, K4, and K5 are gains that vary according to the vehicle speed V.

In the above embodiment, the target braking hydraulic pressure Pgf for the front wheels is described using a specific equation (see the equation (21)). However, it is not limited to this. For example, the target braking hydraulic pressure Pgf for the front wheels may be calculated by the following equation (32).
Pgf = Kgv · V + Kgφ · φ + Kgβ · β (32)
Here, Kgφ and Kgβ are conversion coefficients for converting braking force into braking hydraulic pressure, which are set based on the yaw angle φ and the travel lane curvature β, respectively.

  In the description of the above embodiment, the process of step S3 of the braking / driving force control unit 8 is performed when the degree of departure tendency of the host vehicle with respect to the traveling lane is equal to or greater than a predetermined threshold value. Lane departure tendency determining means for determining the vehicle lane departure tendency determining means, and the processing of the step S32 to step S35 of the braking / driving force control unit 8 determines that the lane departure tendency determination means determines that the lane departure tendency determination means has a departure tendency. A departure prevention control means for performing a lane departure prevention control for preventing a departure of the host vehicle from the traveling lane in preference to the vehicle speed control by the device is realized, and the step S36 and the step of the braking / driving force control unit 8 are realized. When the lane departure tendency determination means determines that there is no departure tendency, the process of S37 is performed when the departure tendency degree Based on the already there is realized suppressing acceleration suppression means the acceleration of the vehicle by the vehicle speed control device.

It is a schematic block diagram which shows embodiment 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 the ACC, which is the structure of the braking / driving force control unit of the vehicle travel control device. It is a block diagram for demonstrating the ranging signal process part of the said braking / driving force control unit. It is a block diagram for demonstrating the relative speed calculating part of the said braking / driving force control unit. It is a block diagram for demonstrating the inter-vehicle distance control part of the said braking / driving force control unit. It is a block diagram for demonstrating the inter-vehicle distance control part of the said braking / driving force control unit. It is a block diagram for demonstrating the target inter-vehicle distance setting part of the said braking / driving force control unit. 4 is a flowchart showing the processing contents of a braking / driving force control unit for performing lane departure prevention control in the vehicle travel control device. It is a flowchart which shows the processing content of the lane departure tendency determination by the said braking / driving force control unit. It is a diagram used for explanation of the estimated lateral displacement Xs and deviation judgment threshold value X _{L 1.} It is a flowchart which shows the processing content of the control method for the lane departure prevention by the said braking / driving force control unit. It is a characteristic view used for description of coefficient (alpha) for suppressing acceleration of a vehicle. It is a characteristic view which shows the relationship between the own vehicle speed V and the gain K2. It is a characteristic view which shows the relationship between the own vehicle speed V and the gains Kgv and Kgx. It is a figure used for explanation of the effect of the present invention, and is a figure showing a situation when the own vehicle has lost the preceding vehicle from the state where the own vehicle follows the preceding vehicle. It is a figure which shows the change of the estimated lateral position Xs when the own vehicle has lost the preceding vehicle.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control unit 8 Braking / driving force control unit 9 Engine 12 Driving torque control unit 13 Imaging unit 14 Navigation device 16 Radar 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 22 FL-22RR Wheel speed sensor 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 (7)

  When the degree of departure tendency of the host vehicle with respect to the traveling lane is equal to or greater than a predetermined threshold value, it is determined that there is a tendency of departure of the host vehicle with respect to the traveling lane, and lane departure prevention control is performed with priority over vehicle speed control. When it is determined that there is no tendency, a vehicle travel control apparatus that suppresses acceleration by vehicle speed control based on the degree of departure tendency. A vehicle speed control device for controlling the vehicle speed of the host vehicle;
A lane departure tendency determination means for determining a departure tendency of the host vehicle with respect to the traveling lane when the degree of departure tendency of the host vehicle with respect to the traveling lane is a predetermined threshold value or more;
When the lane departure tendency determination means determines that there is a departure tendency, departure prevention control for performing lane departure prevention control for preventing departure of the host vehicle from the traveling lane in preference to vehicle speed control by the vehicle speed control device. Means,
When it is determined by the lane departure tendency determination means that there is no departure tendency, acceleration suppression means for suppressing acceleration of the host vehicle by the vehicle speed control device based on the degree of departure tendency;
A vehicle travel control device comprising:   3. The vehicle travel control device according to claim 2, wherein the acceleration suppression unit reduces the degree of suppression of acceleration of the host vehicle by the vehicle speed control unit as the degree of departure tendency of the host vehicle is lower.   The acceleration suppression means corrects the acceleration of the vehicle speed control means to a small value when the degree of departure tendency is equal to or greater than a first set value smaller than a predetermined threshold and less than the predetermined threshold. 4. The vehicle travel control device according to claim 2, wherein an acceleration of the vehicle speed control means is set to 0 when the threshold value is equal to or greater than a threshold value.   The said departure prevention control means gives a yaw moment to the own vehicle in a direction opposite to the departure direction after issuing an alarm as lane departure prevention control. Vehicle travel control device. The vehicle speed control device detects the preceding vehicle, and follows the preceding vehicle at a predetermined inter-vehicle distance. When the preceding vehicle cannot be detected, the vehicle speed control device travels at a preset vehicle speed. Calculation means for calculating the target acceleration / deceleration, and vehicle speed control means for controlling the vehicle speed of the host vehicle according to the target acceleration / deceleration,
6. The vehicle travel control apparatus according to claim 2, wherein the acceleration suppression unit corrects the target acceleration calculated by the calculation unit to suppress acceleration.   7. The vehicle travel control device according to claim 2, wherein the lane departure prevention control applies a yaw moment to the host vehicle by generating a braking force difference between the left and right wheels. 8.

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