JP2007030848A - Lane departure preventive device, and vehicle traveling control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent lane departure while satisfying a request for deceleration when requesting the deceleration by the vehicle speed control. <P>SOLUTION: A vehicle traveling control device controls the lane departure prevention in place of the vehicle speed control when the vehicle speed control tries to decelerate the own vehicle (Step S31) in a case of a tendency of lane departure, and adjusts the braking force for controlling the lane departure prevention to the value for satisfying the degree of deceleration (Steps S32-S37) while preventing deviation of the own vehicle from a traveling lane. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a lane departure prevention device that prevents a departure when the host vehicle is about to depart from the traveling lane, and such a lane departure prevention device and a vehicle speed control device that controls the vehicle speed of the host vehicle. The present invention relates to a travel control device for a vehicle to be mounted.

As a conventional lane departure prevention device, when the host vehicle may deviate from the driving 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 moves from the driving lane. There is an apparatus that prevents deviation (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-112540

  By the way, when the conventional lane departure prevention device and a vehicle speed control device such as ACC (Adaptive Cruise Control) are used in combination, when the scenes that these devices should operate overlap, each device cannot perform its function. End up. In other words, if priority is given to the vehicle speed control by the vehicle speed control device when the scenes to be operated by these devices overlap, the function of the lane departure prevention device is hindered, and the own vehicle deviates from the lane, and vice versa. If priority is given to the lane departure prevention control by the lane departure prevention device, the function of the vehicle speed control device is hindered and the vehicle speed required by the vehicle speed control device cannot be achieved.

In particular, the lane departure prevention device is necessary to prevent the vehicle from deviating from the lane, and even when the vehicle speed control device requests deceleration, the lane departure prevention device is given priority. If priority is given to the control by the prevention device, the host vehicle may approach a preceding vehicle (particularly when the preceding vehicle is decelerating), which may cause the driver to feel uncomfortable.
The present invention has been made in view of the above-described problems, and is intended for cooperation between a lane departure prevention device and a vehicle speed control device such as ACC, and in particular, when the vehicle speed control device requests deceleration. An object of the present invention is to provide a lane departure prevention device and a vehicle travel control device that can prevent the lane departure while satisfying the deceleration request.

The lane departure prevention device according to claim 1 is a lane that performs lane departure prevention control that applies braking force to wheels when the host vehicle tends to depart from the traveling lane to prevent the host vehicle from deviating from the traveling lane. Deviation prevention device.
The lane departure prevention device performs the lane departure prevention control instead of the vehicle speed control when the vehicle tends to deviate during vehicle speed control, prevents the own vehicle from deviating from the traveling lane, and controls the vehicle speed control. The braking force is applied so as to realize the deceleration controlled by.

  According to the lane departure prevention apparatus of the first aspect, when deceleration is requested by the vehicle speed control, the lane departure can be prevented while satisfying the deceleration request.

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 a 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 illustrating an 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, 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 a 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.
In addition, this vehicle is used for ACC (adaptive cruise control) that constitutes the vehicle speed control device, by sweeping laser light forward and receiving reflected light from a preceding obstacle so that the host vehicle and the front obstacle A radar 16 is provided for measuring the distance between and the like. A specific configuration for realizing ACC will be described in detail later.

  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 Yg ^* from the difference value between the target vehicle speed V ^* and the host vehicle speed Vsp by, for example, a known procedure by PID (proportional-integral-derivative) control. ^{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 Yg ^* can be realized. Conversely, the target acceleration / deceleration Yg ^* is a positive value. In this case, the drive torque control unit 12 and an automatic transmission (not shown) are controlled so that the target acceleration / deceleration 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 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 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, processing contents of the lane departure prevention control (lane departure prevention apparatus) will be described.
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 calculation process is executed by a timer interrupt 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, the lateral acceleration Xg, the yaw rate φ ′ and the road information obtained by the navigation device 14, the wheel speeds Vwi, the steering angle δ, the accelerator opening θt, the master cylinder hydraulic pressure detected by the sensors. 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.
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, the estimated lateral displacement Xs of the lateral position of the vehicle center of gravity after a predetermined time 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.
According to the equation (18), the estimated lateral displacement Xs increases as the yaw angle φ increases, for example, when focusing on the yaw angle φ.

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 (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.

Further, the deviation tendency determination threshold value _XL is set to be smaller as the inter-vehicle distance L becomes shorter. FIG. 11 shows an example of the setting. As shown in FIG. 11, when the inter-vehicle distance L is small, the departure tendency determination threshold value _XL is a certain small value, and when the inter-vehicle distance L is greater than a certain value, the inter-vehicle distance L and the deviation tendency determination The threshold value _XL is in a proportional relationship, and when the inter-vehicle distance L is further increased, the departure tendency determination threshold value _XL is a certain large value.

As a result, as shown in FIG. 12, when the inter-vehicle distance L between the host vehicle 100 and the preceding vehicle 101 is large, the departure tendency determination threshold value _XL is increased ((a) in FIG. 12). As the distance L decreases, the departure tendency determination threshold value _XL also decreases ((b) in the figure).
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 Fout 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.

Further, as described above, as the inter-vehicle distance L becomes shorter, since the small departure-tendency threshold value X _L (see FIG. 11), as the inter-vehicle distance L becomes shorter, the estimated lateral displacement Xs is for determining the tendency to deviate easily becomes more than the threshold value X _L, i.e., more likely to be determined that there is 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 S3.
Subsequently, in step S4, 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 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 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 S5, if the departure determination flag Fout is ON as a result of the processing in step S4, 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 host vehicle is started as the lane departure prevention control. Therefore, the alarm is output simultaneously with the application of the yaw moment to the host vehicle. 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 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 (departure-tendency threshold value) X _L in the step S3.
Ms = K1 · K2 · (| Xs | −X _L ) (20)
Here, K1 is a proportional gain 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 has a large value in the low speed range, and when the vehicle speed V reaches a certain value, it has an inversely proportional relationship with the vehicle speed V. Become.

According to the (20) equation, the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _L is, 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.
Subsequently, in step S7, a braking method is determined based on the deceleration requested by the ACC.

  In the lane departure prevention control, a yaw moment is applied to the host vehicle by generating a braking force difference between the left and right wheels, and the host vehicle is prevented from deviating from the traveling lane. The method for generating the braking force difference is determined. Specifically, a method of generating a braking force difference is determined so that the host vehicle decelerates at a deceleration required by the ACC while giving a yaw moment to the host vehicle.

Here, by applying braking force to only one of the left and right wheels or generating braking force on both the left and right wheels, while increasing the braking force of the vehicle on one side, the braking force difference between the left and right wheels can be reduced. Can be generated. In order to prevent lane departure, it is necessary to increase the braking force of the wheel on the departure avoidance side in any case.
Here, FIG. 14 shows the relationship between the braking force difference between the left and right wheels and the deceleration (negative Yg) of the host vehicle when the braking force difference is generated. As shown in FIG. 14, when the braking force difference between the left and right wheels is increased, the deceleration component acting on the host vehicle is increased, so that the deceleration Yg (absolute deceleration) of the host vehicle is also increased.

  FIG. 15 shows the relationship between the target yaw moment Ms and the braking force difference between the left and right wheels. As shown in FIG. 15, when the braking force difference between the left and right wheels is increased, the target yaw moment Ms is also increased. Therefore, from these relationships shown in FIGS. 14 and 15, if it is desired to increase the deceleration Yg of the host vehicle, the target yaw moment Ms may be increased by increasing the braking force difference.

  Thus, if the braking force difference is increased, that is, if the braking force of the wheel on one side is increased, the deceleration Yg of the vehicle can be increased. However, since the tire has a braking force limit, there is a limit to the braking force that can be generated on one wheel, so it can be given to the host vehicle only by increasing the braking force on one wheel. There is a limit to the deceleration Yg that can be achieved. However, in such a case, if the braking force is generated on both the left and right wheels and the braking force on one wheel is increased to generate a braking force difference between the left and right wheels, the deceleration Yg of the host vehicle is generated. Even if is increased, the wheel on one side does not easily reach the braking force limit, so that a large deceleration Yg can be generated in the own vehicle while ensuring the target yaw moment Ms.

Considering the circumstances as described above, in this step S7, a method for generating a braking force difference between the left and right wheels is determined. The determination procedure is specifically shown in FIG.
First, in step S31, it is determined whether the inter-vehicle distance control execution flag _SF is 1. Here, when the inter-vehicle distance control execution flag _SF is 1 (S _F = 1), that is, the ACC performs inter-vehicle distance control (follow-up control) for controlling the vehicle speed of the own vehicle so as to follow the preceding vehicle. If the vehicle distance control execution flag _SF is not 1 (S _F = 0), that is, if the vehicle distance control is not performed by ACC, the process proceeds to step S36. When the inter-vehicle distance control execution flag _SF is 1, the target acceleration / deceleration Yg ^* used for vehicle speed control in the ACC is read. Here, when the target acceleration / deceleration Yg ^* is a negative value, deceleration is indicated, and when the target acceleration / deceleration Yg ^* is a positive value, acceleration is indicated. This process assumes a scene in which ACC (particularly inter-vehicle distance control) requires deceleration of the host vehicle, that is, mainly deals with a negative target acceleration / deceleration Yg ^* .

In step S32, it is determined whether or not the target acceleration / deceleration Yg ^* is greater than zero. If the target acceleration / deceleration Yg ^* is larger than 0 (Yg ^* > 0), that is, if acceleration is requested by ACC, the process proceeds to step S36, and the target acceleration / deceleration Yg ^* is 0 or less (Yg ^* ≦ 0), that is, when the deceleration is requested by ACC, the process proceeds to step S33.

In step S33, it is determined whether or not the target acceleration / deceleration Yg ^* is greater than a first braking method switching determination threshold (first threshold) Ygth1 (<0). If the target acceleration / deceleration Yg ^* is larger than the first braking method switching determination threshold Ygth1 (Yg ^* > Ygth1), the process proceeds to step S36, where the target acceleration / deceleration Yg ^* is the first braking method switching determination threshold. If Ygth1 or less (Yg ^* ≦ Ygth1), the process proceeds to step S34.

In step S34, the target acceleration / deceleration Yg ^* is greater than a second braking method switching determination threshold (second threshold) Ygth2 (<Ygth1 <0) less than the first braking method switching determination threshold Ygth1. It is determined whether or not. If the target acceleration / deceleration Yg ^* is larger than the second braking method switching determination threshold Ygth2 (Yg ^* > Ygth2), the process proceeds to step S35, where the target acceleration / deceleration Yg ^* is the second braking method switching determination threshold. If Ygth2 or less (Yg ^* ≦ Ygth2), the process proceeds to step S37.

In step S36, it is determined that the yaw moment is applied to the host vehicle by applying a braking force to the departure avoiding wheel without correcting the target yaw moment Ms calculated in step S6. In this case, the braking method switching determination flag Fch is set to 0.
In step S35, the target yaw moment Ms calculated in step S6 is corrected, and it is determined that a braking force is applied to the deviation avoidance wheel to apply the yaw moment to the host vehicle. In this case, the braking method switching determination flag Fch is set to 1.

Here, the degree of correction of the target yaw moment Ms is such that the deceleration generated in the host vehicle by applying a braking force to the departure avoiding wheel satisfies the target acceleration / deceleration Yg ^*. Increase the yaw moment Ms.
In step S37, the yaw moment is applied to the host vehicle by generating a braking force difference between the left and right wheels while applying a braking force to the left and right wheels without correcting the target yaw moment Ms calculated in step S6. Decide to grant. In this case, the braking method switching determination flag Fch is set to 2.
Thus, the generation method of the braking force difference is determined in step S35, step S36, or step S37, and the process (step S7) shown in FIG. 16 ends.

FIG. 17 shows the results obtained by the above processing. That is, when the deceleration is requested by ACC, if the target acceleration / deceleration Yg ^* is larger than the first braking method switching determination threshold Ygth1 (0 ≧ Yg ^* > Ygth1), that is, the deceleration is small by ACC. , It is determined that the yaw moment is applied to the host vehicle by applying the braking force only to the departure avoiding wheel without correcting the target yaw moment Ms (step S36, Fch = 0). .

Further, if the target acceleration / deceleration Yg ^* requested by ACC is equal to or smaller than the first braking method switching determination threshold Ygth1 and larger than the second braking method switching determination threshold Ygth2 (Ygth1 ≧ Yg ^* > Ygth2). That is, when a moderate deceleration is requested in ACC, the target yaw moment Ms is corrected so as to increase as the target acceleration / deceleration Yg ^* increases, and the braking force is applied only to the wheels on the departure avoidance side. It is determined to give a yaw moment to the vehicle (step S35, Fch = 1).

If the target acceleration / deceleration Yg ^* requested by ACC is equal to or smaller than the second braking method switching determination threshold Ygth2 (Ygth2 ≧ Yg ^* ), that is, if a large deceleration is requested by ACC, the target yaw It is determined to apply a yaw moment to the host vehicle by generating a braking force difference between the left and right wheels while applying a braking force to both the left and right wheels without correcting the moment Ms (step S37, Fch = 2). ).

Thus, while the deceleration required by the ACC is small (Fch = 0), the braking force is applied only to the wheels on the departure avoidance side and the yaw moment is applied to the own vehicle, and the own vehicle is determined only by the braking force difference. When the deceleration required by the ACC increases and the target acceleration / deceleration Yg ^* becomes equal to or less than the first braking method switching determination threshold Ygth1 (Fch = 1), the wheel on the departure avoidance side The yaw moment is applied to the host vehicle only by applying a braking force to the host vehicle, but the host vehicle is decelerated by a braking force difference that realizes the target yaw moment Ms by correcting the target yaw moment Ms to be increased. When deceleration becomes larger (Fch = 2), from the time when the target deceleration Yg ^* becomes equal to or less than the second braking process switching judgment threshold Ygth2, the braking force to the right and left wheels granted to While, by generating the braking force difference in the left and right wheels, and applying a yaw moment to the vehicle, and so as to decelerate the vehicle by the braking force difference (the braking force of the four wheels).

  Here, the first braking method switching determination threshold value Ygth1 corresponds to a deceleration component that acts on the host vehicle by the braking force that realizes the target yaw moment Ms before correction (braking force generated only by the wheel on the departure avoidance side). The second braking method switching determination threshold value Ygth2 takes into account the braking limit of the tire (particularly the tire to which braking force is applied to generate the yaw moment on the own vehicle on the departure avoidance side). This is the value that has been determined.

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 lane departure. Specifically, it is calculated as follows.
(1-1) 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 equations (21) and (22), the target braking fluid for each wheel The pressure Psi (i = fl, fr, rl, rr) is set to the brake fluid pressure 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. For example, if the driver is performing a brake operation, the brake fluid pressures Pmf and Pmr are values corresponding to the operation amount of the brake operation.

(1-2) On the other hand, when the departure determination flag Fout is ON, that is, when the determination result that there is a lane departure tendency is obtained and the braking method switching determination flag Fch is 0, the target yaw moment Ms (correction) The front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr are calculated based on the target yaw moment Ms) that has not been corrected. 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 = Kbr · Ms / T (24)
When | Ms | ≧ Ms1 ΔPsf = Kbf · (Ms / | Ms |) · (| Ms | −Ms1) / T (25)
ΔPsr = Kbr · (Ms / | Ms |) · 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 generated by 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 hydraulic pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking hydraulic pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. Further, 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.

(1-3) When the departure determination flag Fout is ON and the braking method switching determination flag Fch is 1, based on the target yaw moment Ms corrected based on the target acceleration / deceleration Yg ^* in step S7. The front wheel target braking fluid pressure difference ΔPsf and the rear wheel target braking fluid pressure difference ΔPsr are calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (27) to (30).
When | Ms | <Ms1 ΔPsf = 0 (27)
ΔPsr = Pd1 (28)
When | Ms | ≧ Ms1 ΔPsf = Pd2 (29)
ΔPsr = Pd3 (30)
Here, Pd1, Pd2, and Pd3 are braking force differences between the left and right wheels for realizing the corrected target yaw moment Ms.

For example, Pd1, Pd2, and Pd3 may be determined by the following equation (31).
Pd1 = Kbr · Msh / T
Pd2 = Kbf · (Msh / | Msh |) · (| Msh | −Ms1) / T
Pd3 = Kbr · (Msh / | Msh |) · Ms1 / T
... (31)
Here, Msh is the target yaw moment after correcting the target yaw moment Ms based on the target acceleration / deceleration Yg ^* .
When the departure determination flag Fout is ON, the final target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated using the target brake hydraulic pressure difference ΔPsf, ΔPsr calculated as described above. ) Is calculated as follows.

(2-1) When the value of the braking method switching determination flag Fch is 0 or 1, that is, by generating a braking force only on the departure avoiding wheel, a braking force difference is generated between the left and right wheels, When the yaw moment is applied, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (32).
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (32)
Here, the target braking hydraulic pressure differences ΔPsf and ΔPsr are expressed by the equations (23) to (26) or the equations (27) to (30) according to the value (0 or 1) of the braking method switching determination flag Fch. Set to the obtained value.

(2-2) When the braking method switching determination flag Fch is 2, that is, without generating the target yaw moment Ms, the braking force is generated on the left and right wheels while the braking force difference is generated on the left and right wheels. When the yaw moment is applied to the host vehicle, the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (33).
Psfl = Pmf + Pd4
Psfr = Pmf + Pd4 + ΔPsf
Psrl = Pmr + Pd4
Psrr = Pmr + Pd4 + ΔPsr
... (33)
Here, Pd4 is a braking force generated in each of the four wheels when a large deceleration is requested in ACC, that is, the target acceleration / deceleration Yg ^* is equal to or less than the second braking method switching determination threshold Ygth2. In some cases, the braking force is generated in each of the four wheels to achieve the target acceleration / deceleration Yg ^* .

And this braking force Pd4 is set so large that the said target acceleration / deceleration Yg ^* becomes large. Further, the target braking hydraulic pressure differences ΔPsf and ΔPsr are the same values as the values obtained when the braking method switching determination flag Fch is 0, that is, the values obtained from the equations (23) to (26). As a result, the host vehicle can be decelerated to the target acceleration / deceleration Yg ^* without correcting the target yaw moment Ms.

Further, as shown by the equations (32) and (33), the brake operation by the driver, that is, the target brake fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
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, a lane departure tendency is determined based on the estimated lateral displacement Xs. 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 S4).

When the departure determination flag Fout is ON, a warning is output (step S5).
On the other hand, the target yaw moment Ms to be given to the vehicle as lane departure prevention control is calculated (step S6). Then, the braking method is determined based on the deceleration required by the ACC. In some cases (when Ygth1 ≧ Yg ^* > Ygth2), the target yaw moment Ms is corrected based on the target acceleration / deceleration Yg ^* .
Subsequently, when the departure determination flag Fout is ON, a braking force is generated on the wheels so that the target yaw moment Ms is applied to the host vehicle as lane departure prevention control (step S8). At this time, a braking force is generated on the wheel based on the previously determined braking method.

  Note that the operation of the ACC is stopped during the operation of the lane departure prevention control. For example, when the own vehicle shows a departure tendency while the own vehicle is following the preceding vehicle by ACC, the lane departure prevention control is activated by the processing as described above. For this reason, when the departure determination flag Fout is turned ON, the vehicle speed control by the ACC is stopped and the lane departure prevention control is made to intervene. When the departure determination flag Fout is turned off, that is, after avoiding the lane departure by the lane departure prevention control, or after avoiding the lane departure by the driver's own driving operation in some cases, the ACC is operated again. I will let you.

By the above series of processes, when there is a tendency to depart from the lane, a yaw moment is given to the host vehicle.
Thus, when deceleration is requested in ACC, if the target acceleration / deceleration Yg ^* is larger than the first braking method switching determination threshold Ygth1 (Yg ^* > Ygth1), that is, a small deceleration is requested in ACC. In this case, as shown in FIG. 18A, the braking force is generated only by the wheels on the departure avoidance side, the yaw moment is applied to the own vehicle, and the lane departure of the own vehicle is avoided.

Further, if the target acceleration / deceleration Yg ^* requested by ACC is equal to or smaller than the first braking method switching determination threshold Ygth1 and larger than the second braking method switching determination threshold Ygth2 (Ygth1 ≧ Yg ^* > Ygth2). That is, when a moderate deceleration is requested in ACC, as shown in FIG. 18A, the braking force is generated only by the wheel on the departure avoidance side and corrected (corrected so as to increase). A yaw moment is applied to the host vehicle to avoid lane departure of the host vehicle.

On the other hand, if the target acceleration / deceleration Yg ^* requested by ACC is equal to or less than the second braking method switching determination threshold Ygth2 (Ygth2 ≧ Yg ^* ), that is, if a large deceleration is requested by ACC, FIG. As shown in (b), by generating a braking force between the left and right wheels and generating a braking force difference between the left and right wheels, a yaw moment is applied to the host vehicle, and a lane departure of the host vehicle is avoided.

As described above, it is possible to avoid the host vehicle deviating from the lane while decelerating the host vehicle at the deceleration required by the ACC.
Further, as described above, so as to become smaller as the departure-tendency threshold value X _L vehicle distance L becomes small, and likely to be determined that there is lane departure tendency. Further, according to the equation (20), the difference between the departure-tendency threshold value X _L and the estimated lateral displacement Xs from calculates the target yaw moment Ms, even when the same estimated lateral displacement Xs, The target yaw moment Ms becomes a large value. Thus, by reducing the extent departure-tendency threshold value X _L vehicle distance L is small, if obtaining the same estimated lateral displacement Xs, i.e. even if they give the equivalent lane departure tendency, a target yaw moment Ms can be set to a larger value than in the normal case (FIG. 19A) (FIG. 19B). As a result, the deceleration component (deceleration) B acting on the host vehicle 100 as lane departure prevention control also becomes larger than the normal case (FIG. 19A) (FIG. 19B). The position of the host vehicle 100 shown in the figure is an estimated lateral displacement position (Xs) after the vehicle head time Tt.

For example, during the follow-up control of the preceding vehicle by ACC, when the preceding vehicle suddenly brakes, especially when the inter-vehicle distance at that time is short, the deceleration required by ACC also increases. On the other hand, the target yaw moment Ms is increased as the inter-vehicle distance L becomes smaller, thereby increasing the deceleration component (deceleration) acting on the host vehicle, so that the ACC increases when the inter-vehicle distance is short. Even when deceleration is required, the required deceleration can be generated by the lane departure prevention control. For example, even when a large deceleration is required in ACC, the opportunity to correct the target yaw moment Ms according to the target acceleration / deceleration Yg ^* is reduced as in step S7, and the required reduction is performed in the lane departure prevention control. You will be able to generate speed.

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 lane departure prevention control is intervened while the ACC is operating, that is, the case where the lane departure prevention control is operated with priority over the ACC has been described. However, it is not limited to this. That is, depending on conditions, ACC and lane departure prevention control may be activated.

FIG. 20 shows an example of a procedure for realizing such processing.
First, in step S41, it is determined whether a lane departure tendency is detected (Fout is ON) or not during deceleration in ACC (S _F = 1). If a lane departure tendency is detected during deceleration at ACC, the process proceeds to step S42, and if not, the process shown in FIG. 20 is terminated.

In step S42, the deceleration component when the lane departure prevention control is activated is acquired. Subsequently, in step S43, the deceleration required by the ACC (target acceleration / deceleration Yg ^* ) is acquired. Note that the deceleration component when the lane departure prevention control is activated is the normal lane departure prevention control when a braking force difference is generated to apply a yaw moment to the host vehicle. The deceleration that acts.

Subsequently, in step S44, it is determined whether or not the deceleration component (deceleration) acquired in step S42 is equal to or greater than the required deceleration of ACC acquired in step S43. If the deceleration component (deceleration) is greater than or equal to the required deceleration of the ACC, the process proceeds to step S45. If the deceleration component (deceleration) is less than the required deceleration of the ACC, the process proceeds to step S46.
In step S45, the lane departure prevention control is operated as usual without changing the correction of the target yaw moment Ms and the wheel braking method.

Further, in step S46, the lane departure prevention control is operated while maintaining the operation without stopping the ACC. The operation of the lane departure prevention control here is a normal operation of the lane departure prevention control without correcting the target yaw moment Ms or changing the wheel braking method.
By the processing as described above, the ACC and the lane departure prevention control are operated. Thereby, when the required deceleration of ACC is small, only lane departure prevention control is operated. On the other hand, when the required deceleration of ACC becomes large to some extent, ACC and lane departure prevention control are activated. Thus, the ACC and the lane departure prevention control can be coordinated without changing the arithmetic processing for correcting the target yaw moment Ms and the wheel braking method.

  In the above-described embodiment, the case where the yaw moment is applied to the host vehicle to prevent the lane departure as the lane departure prevention control has been described. However, it is not limited to this. For example, as the lane departure prevention control, the host vehicle may be decelerated in the traveling direction (hereinafter referred to as lane departure prevention deceleration control). In this case, for example, when the departure tendency becomes large due to an increase in the yaw angle with respect to the traveling road, the deceleration control for preventing lane departure is performed, and the timing to perform the control is just before the yaw moment is applied. Or at the same time that the yaw moment is applied. The lane departure prevention deceleration control performed as the lane departure prevention control is used to satisfy the ACC required deceleration. For example, if the required deceleration of ACC is large, correction for increasing the deceleration by deceleration control for preventing lane departure is performed, or even if the timing at which deceleration control for preventing lane departure is not originally performed, If the deceleration is large, deceleration control for preventing lane departure is started. Thereby, like the previous embodiment, it is possible to avoid the departure of the host vehicle while decelerating the host vehicle at the deceleration required by the ACC.

Moreover, in the said embodiment, it demonstrates on the assumption that the inter-vehicle distance control (follow-up control) which controls the vehicle speed of the own vehicle so that a preceding vehicle may be followed by ACC is implemented. However, it is not limited to this. For example, the lane departure prevention control may be made to intervene when deceleration is requested in the vehicle speed control in a travel scene other than following the preceding vehicle.
Moreover, in the said embodiment, it demonstrated paying attention to the target acceleration / deceleration of ACC. However, it is not limited to this. In other words, since the target acceleration / deceleration of ACC is originally intended to achieve the target vehicle speed, the target vehicle speed may be processed. That is, in this case, in the lane departure prevention control, the braking force is applied so as to prevent the own vehicle from departing from the traveling lane and to realize the speed of the own vehicle controlled by the vehicle speed control.

  In the description of the above embodiment, the process of step S31 by the braking / driving force control unit 8 realizes a requested speed detecting means for detecting the speed of the host vehicle required by the vehicle speed control, and the braking / driving force control unit 8 The processing of step S6 and step S8 by the above-described control realizes a departure-preventing braking force calculation means for calculating a braking force necessary to prevent the vehicle from deviating from the traveling lane in the lane departure prevention control. The processing of step S7 (steps S32 to S37) and step S8 by the driving force control unit 8 is performed on the host vehicle based on the speed detected by the required speed detection means and the braking force calculated by the departure prevention braking force calculation means. Based on the applied deceleration, a braking force adjusting means for adjusting the braking force is realized. Processing in step S8 by chromatography Ruyunitto 8, wherein as the braking force adjusting means is a braking force is adjusted, thereby realizing a braking force control means for controlling the braking forces of the wheels.

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 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 flowchart which shows the processing content of the control unit which comprises a lane departure prevention apparatus in the travel control apparatus of a vehicle. 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 the departure tendency determination threshold value X _L. It is a characteristic diagram showing the relationship between the inter-vehicle distance L and departure-tendency threshold value X _L. It is a diagram used for explaining a relationship between the inter-vehicle distance L and departure-tendency threshold value X _L. It is a characteristic view which shows the relationship between the vehicle speed V and the gain K2. It is a characteristic view which shows the relationship between a braking force difference and deceleration Yg. FIG. 5 is a characteristic diagram showing a relationship between a braking force difference and a target yaw moment Ms. It is a flowchart which shows the processing content for the braking method determination by the said control unit. It is the figure used for description of the processing result of the braking method determination. It is a figure used for description of the braking method determined based on the target acceleration / deceleration Yg ^* . It is the figure used in order to explain the target yaw moment Ms when the inter-vehicle distance L is small and the deceleration B acting on the host vehicle when the target yaw moment Ms is applied to the host vehicle. It is the flowchart used for description of other embodiment.

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 22FL to 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 (11)

In a lane departure prevention device that performs lane departure prevention control that applies braking force to wheels when the host vehicle tends to deviate from the traveling lane to prevent the host vehicle from departing from the traveling lane,
When there is a tendency to deviate during the vehicle speed control, the lane departure prevention control is performed in place of the vehicle speed control, the vehicle is prevented from deviating from the traveling lane, and the deceleration controlled by the vehicle speed control is controlled. A lane departure prevention device characterized in that the braking force is applied so as to realize the following. The lane departure prevention control is to prevent the host vehicle from deviating from the traveling lane by generating a braking force difference between the left and right wheels and applying a yaw moment to the host vehicle.
2. The lane departure prevention apparatus according to claim 1, wherein the yaw moment is determined so that a deceleration component acting on the host vehicle due to a difference in braking force between the left and right wheels satisfies the deceleration.   3. The lane departure prevention device according to claim 1, wherein when the deceleration component acting on the host vehicle due to a difference in braking force between the left and right wheels is larger than the deceleration, the magnitude of the yaw moment is maintained. . Requested speed detecting means for detecting the speed of the host vehicle required by the vehicle speed control;
Departure prevention braking force calculation means for calculating the braking force of the wheels necessary to prevent the vehicle from deviating from the traveling lane in the lane departure prevention control;
Braking force adjusting means for adjusting the braking force based on the speed detected by the required speed detecting means and the deceleration acting on the host vehicle by the braking force calculated by the departure preventing braking force calculating means;
Braking force control means for controlling the braking force of the wheels so that the braking force adjusted by the braking force adjustment means is obtained;
A vehicle travel control device comprising:   The requested speed detecting means detects the deceleration of the host vehicle required by the vehicle speed control, and the braking force adjusting means adjusts the braking force based on the deceleration detected by the requested speed detecting means. The vehicle travel control apparatus according to claim 4.   The braking force adjusting means adjusts the braking force so that the deceleration acting on the host vehicle is not reduced by the braking force calculated by the departure prevention braking force calculating means than the deceleration detected by the required speed detecting means. 6. The vehicle travel control device according to claim 5, wherein The lane departure prevention control is to prevent the host vehicle from deviating from the traveling lane by generating a braking force difference between the left and right wheels and applying a yaw moment to the host vehicle.
The departure-preventing braking force calculating means calculates a braking force required for generating a braking force difference between the left and right wheels, and the braking force adjusting means acts on the host vehicle due to the braking force difference between the left and right wheels. The vehicle travel control apparatus according to claim 5 or 6, wherein the braking force is adjusted so that a deceleration component does not become smaller than the deceleration detected by the required speed detection means. In the lane departure prevention control, a braking force is applied only to the wheels on the departure avoidance side to generate a braking force difference between the left and right wheels, thereby giving a yaw moment to the own vehicle, and applying a braking force to both the left and right wheels. It is possible to switch between giving a yaw moment to the host vehicle by generating a braking force difference between the left and right wheels by increasing the braking force on the departure avoidance side wheel,
When the deceleration detected by the required speed detection means is less than a first threshold value, the braking force adjusting means generates a braking force difference between the left and right wheels by applying a braking force only to the deviation avoidance side wheel. In the case where the braking force is maintained as it is and the deceleration detected by the required speed detecting means is not less than the first threshold and less than the second threshold greater than the first threshold, While generating a braking force difference between the left and right wheels by applying a braking force only to the departure avoiding wheel, the braking force adjusting means increases the braking force so that the braking force difference is increased, When the deceleration detected by the required speed detection means is equal to or greater than the second threshold value, a braking force is applied to the left and right wheels by applying a braking force to both the left and right wheels and increasing the braking force on the departure avoiding wheel. Is generated by the braking force adjusting means. , The travel control device for a vehicle according to claim 7, characterized in that the said request speed detecting means for adjusting the braking force applied to the right and left wheels based on the deceleration detected. The vehicle speed control controls the vehicle speed of the host vehicle so as to follow the preceding vehicle, and the lane departure prevention control compares a value indicating the running state of the host vehicle with a departure tendency determination threshold value. In addition to judging the departure tendency, the larger the difference between the value indicating the running state of the host vehicle with respect to the departure tendency judgment threshold, the greater the braking force of the own vehicle, thereby preventing the departure of the host vehicle from the running lane. Is what
9. The deviation tendency determination threshold value is corrected in a direction in which it is easier to determine that there is a deviation tendency as the distance between the preceding vehicle and the host vehicle becomes shorter. The vehicle travel control apparatus described. Requested speed detection means for detecting the deceleration of the host vehicle required by the vehicle speed control;
Departure prevention braking force calculation means for calculating a braking force necessary to prevent the vehicle from deviating from the traveling lane in the lane departure prevention control;
Of the vehicle speed control and the lane departure prevention control, based on the deceleration detected by the required speed detection means and the deceleration acting on the host vehicle by the braking force calculated by the departure prevention braking force calculation means. Selection actuating means for preferentially actuating one of
A vehicle travel control device comprising:   When the deceleration detected by the required speed detection means is equal to or less than the deceleration calculated by the departure prevention braking force calculation means, the selection operation means preferentially operates the lane departure prevention control, and the required speed 11. The vehicle speed control and the lane departure prevention control are both activated when the deceleration detected by the detection means is greater than the deceleration calculated by the departure prevention braking force calculation means. The vehicle travel control apparatus described.

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