JP2006182129A - Preventing device of deviation from lane - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preventing device of deviation from a lane capable of controlling avoidance of deviation from the lane without giving sense of incongruity to a driver of a succeeding vehicle. <P>SOLUTION: The preventing device of deviation from the lane provides the yaw moment Ms smaller than a regular value to a self vehicle 100 at the timing earlier than the regular one when the self vehicle 100 is likely deviated from the lane, and a rear lateral succeeding vehicle 101 is approaching the self vehicle 100 in an adjacent lane. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lane departure prevention device for preventing a departure when a vehicle tends to depart from a traveling lane.

As a conventional lane departure prevention device, when a vehicle tends to depart from a traveling lane, a device that performs departure avoidance control by giving a yaw moment to the host vehicle based on the estimated departure amount is proposed (for example, Patent Document 1). reference).
Japanese Patent Laid-Open No. 2003-112540

However, when there is a vehicle behind the host vehicle and the yaw moment is applied to avoid lane departure, the vehicle behavior of the host vehicle at that time may cause the driver of the rear vehicle to feel uncomfortable. is there.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a lane departure prevention device that can perform lane departure avoidance control without causing a driver of a rear vehicle to feel uncomfortable.

  The lane departure prevention apparatus according to the present invention provides a yaw moment to the host vehicle when the lane departure tendency determination unit that determines the departure tendency of the host vehicle with respect to the traveling lane and the lane departure tendency determination unit determine that there is a departure tendency. And departure avoidance control means for avoiding the departure of the host vehicle from the traveling lane. This lane departure prevention device detects another vehicle behind the host vehicle by the rear vehicle detection means, and when the rear vehicle detection means detects another vehicle behind the host vehicle, the yaw moment given by the departure avoidance control means Is corrected by the control correction means, and the time for giving the yaw moment is lengthened.

  According to the present invention, when another vehicle is detected behind the host vehicle, the yaw moment given by the departure avoidance control unit is suppressed, and the time during which the yaw moment is applied is lengthened so that the behavior of the host vehicle is This can prevent the driver from feeling uncomfortable.

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 the lane departure prevention apparatus 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.

Further, this vehicle is provided with an obstacle detection radar around the host vehicle. Specifically, a rear obstacle detection radar 31, rear side obstacle detection radars 32 and 33, and a side obstacle detection radar 34 are provided.
The rear obstacle detection radar 31 detects an obstacle (vehicle or the like) behind the host vehicle, and detects a relative speed Vbr and a relative distance Lbr with the obstacle. The rear obstacle detection radar 31 calculates a collision time TTC (Time To Collision). The collision time TTC is a value obtained as a ratio (distance / relative speed) between the distance from the host vehicle to the rear obstacle (relative distance Lbr) and the relative speed (Vbr) with the rear obstacle. This is an index indicating whether there is a risk that an obstacle behind the vehicle will collide with the host vehicle in seconds. Hereinafter, the collision time TTC calculated by the rear obstacle detection radar 31 is referred to as a first collision time TTCbr.

  The rear side obstacle detection radars 32 and 33 detect an obstacle (vehicle or the like) on the rear left and right sides of the own vehicle, and also detect a relative speed Vbsr and a relative distance Lbsr with the obstacle. . The rear side obstacle detection radars 32 and 33 calculate a collision time TTC (Time To Collision). Here, the collision time TTC calculated by the rear side obstacle detection radars 32 and 33 is the distance between the host vehicle and the rear side obstacle (relative distance Lbsr) and the rear side obstacle. It is a value obtained as a ratio (distance / relative speed) to the relative speed (Vbsr). Hereinafter, the collision time TTC calculated by the rear side obstacle detection radars 32 and 33 is referred to as a second collision time TTCbs.

Further, the side obstacle detection radars 34 and 35 detect obstacles (vehicles and the like) on the left and right sides of the own vehicle, and also detect a relative speed Vbsr and a relative distance Lbsr with the obstacle.
The obstacle detection radars 31 to 35 output the detection result and the calculation result to the braking / driving force control unit 8.
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.
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. The steering angle sensor 19 for detecting the steering angle δ of the steering wheel 21, the direction indicating switch 20 for detecting the direction indicating operation by the direction indicator, and the rotational speeds of the wheels 5FL to 5RR, so-called wheel speed Vwi (i = fl, Wheel speed sensors 22FL to 22RR for detecting 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 left direction is the positive direction. That is, the yaw rate φ ′, the lateral acceleration Xg, and the yaw angle φ are positive values when turning left, and the lateral displacement X is a positive value when deviating leftward from the center of the traveling lane. The longitudinal acceleration Yg takes a positive value during acceleration and takes a negative value during deceleration.

  Next, a calculation processing procedure 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. 2, 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 road information obtained by the navigation device 14, the obstacle detection information obtained by the obstacle detection radars 31 to 35, and the relative speed with the obstacle. Relative distance, collision time, wheel speed Vwi, steering angle δ, accelerator opening θt, master cylinder hydraulic pressures Pmf, Pmr and direction switch signal detected by each sensor, and drive torque Tw from drive torque control unit 12 Then, the yaw angle φ, the lateral displacement X, and the 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 (1) 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
... (1)
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 (1), the vehicle speed V is calculated as an average value of the wheel speeds of the driven wheels. In this embodiment, since the vehicle is a rear-wheel drive vehicle, the vehicle speed V is calculated from the latter equation, that is, the wheel speed of the front wheels.

The vehicle speed V calculated in this way is preferably used during normal travel. For example, when an ABS (Anti-lock Brake System) control or the like is operating, an estimated vehicle speed estimated in the ABS control is used as the vehicle speed V. A value used for navigation information in the navigation device 14 may be used as the vehicle speed V.
Subsequently, in step S3, a vehicle detection flag around the host vehicle is set. The processing procedure of this processing is specifically as shown in FIG.

  First, in step S21, a rear vehicle is detected using a rear vehicle detection threshold. Specifically, when the first collision time TTCbr calculated by the rear obstacle detection radar 31 read in step S1 is larger than the rear vehicle detection threshold Tbrth (TTCb> Tbrth), the vehicle is rearward near the host vehicle. It is determined that there is a vehicle. In other cases (TTCbr ≦ Tbrth), it is determined that there is no rear vehicle near the host vehicle.

Subsequently, in step S22, a rear vehicle detection flag is set. Specifically, when it is determined in step S21 that there is a rear vehicle near the host vehicle, the rear vehicle detection flag Fbr is set to 1, and when it is determined that there is no rear vehicle near the host vehicle, the rear vehicle detection flag is set. Set Fbr to 0.
Subsequently, in step S23, the rear side vehicle is detected using the rear side vehicle detection threshold. Specifically, when the second collision time TTCbs calculated by the rear side obstacle detection radars 32 and 33 read in step S1 is larger than the rear vehicle detection threshold Tbsth (TTCbs> Tbsth), It is determined that there is a rear side vehicle near the vehicle. In other cases (TTCbs ≦ Tbsth), it is determined that there is no rear side vehicle near the host vehicle.

Subsequently, in step S24, a rear side vehicle detection flag is set. Specifically, when it is determined in step S23 that there is a rear side vehicle near the host vehicle, the rear side vehicle detection flag Fbsr is set to 1, and it is determined that there is no rear side vehicle near the host vehicle. The post-measurement vehicle detection flag Fbsr is set to zero.
Subsequently, in step S25, a rear side vehicle detection flag is set. Specifically, when a vehicle is detected to the side of the host vehicle from the detection results of the side obstacle detection radars 34 and 35 read in step S1, the side vehicle detection flag Fsr is set to 1, If no vehicle is detected on the side of the host vehicle, the side vehicle detection flag Fsr is set to zero.

Subsequently, in step S4, a lane departure tendency is determined. The procedure of this determination process is specifically as shown in FIG. FIG. 5 illustrates the definition of values used in this process.
First, in step S31, 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 traveling 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 expressed by the following equation (2). Xs is calculated.
Xs = Tt · V · (φ + Tt · V · β) + X0 (2)

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 (2), the estimated lateral displacement Xs increases as the yaw angle φ increases, for example, when focusing on the yaw angle φ.

Subsequently, in step S32, it is determined whether or not the rear side vehicle detection flag Fbsr set in step S3 (step S24) is 1, that is, whether there is a rear side vehicle near the host vehicle. If the rear side vehicle detection flag Fbsr is 1, the process proceeds to step S35. If the rear side vehicle detection flag Fbsr is not 1 (Fbsr = 0), the process proceeds to step S33.
Subsequently, in step S33, it is determined whether or not the side vehicle detection flag Fsr set in step S3 (step S25) is 1, that is, whether there is a vehicle on the side of the host vehicle. If the side vehicle detection flag Fsr is 1, the process proceeds to step S35. If the side vehicle detection flag Fsr is not 1 (Fsr = 0), the process proceeds to step S34.

At step S34, it sets the departure-tendency threshold value _{X L} to a predetermined value _{X L0.} The predetermined value X _L0 is a value that can be generally grasped as the vehicle tends to depart from the lane, and is obtained through experiments or the like. For example, the predetermined value X _L0 is a value indicating the position of the boundary line of the travel path, and is calculated by the following equation (3).
X _L0 = (L−H) / 2 (3)
Here, L is the lane width, and H is the width of the vehicle. The lane width L is obtained by the imaging unit 13 processing the captured image. Further, the vehicle position may be obtained from the navigation device 14 or the lane width L may be obtained from the map data of the navigation device 14.

Then, after setting the departure tendency determination threshold value to the predetermined value X _L0 , the process proceeds to step S36.
On the other hand, in step S35, the threshold value for departure tendency determination is set to a predetermined value _XLd . The predetermined value X _Ld is a value smaller than the predetermined value X _Ld set as the departure tendency determination threshold value in the step S34 (X _Ld <X _L0 ).
Then, after setting the departure-tendency threshold value to a predetermined value X _Ld, the process proceeds to step S36.

In step S36, departure determination is performed. Specifically, comparing the estimated lateral displacement Xs and the step S34 or departure-tendency threshold value X _L set at step S35. Here, the estimated lateral displacement when Xs is equal to or greater than the threshold value X _L for determining the tendency to deviate (| Xs | ≧ X _L), determines that there is a lane departure tendency, deviation estimated lateral displacement Xs is given for determining the tendency threshold If it is less than the value _{X L (| Xs | <X} L), determines that there is no lane departure tendency.

Subsequently, in step S37, the departure determination flag Fout is set. That is, if it is determined in step S36 that there is a tendency to depart from the lane (| Xs | ≧ X _L ), the departure determination flag Fout is turned ON (Fout = ON). Further, in the step S36, 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 S36 and step S37, 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, if the braking control for avoiding the deviation described later is performed or the driver himself performs an avoidance operation, the deviation determination flag Fout is changed from ON to OFF.

Also, if there is a rear side vehicle and the next vehicle near the vehicle (FBSR = 1 or Fsr = 1), since the de-tendency threshold value _{X L} is set to a small value _{(X Ld),} When the host vehicle is away from the center of the lane, the departure determination flag Fout is set to ON early.
Subsequently, in step S38, the departure direction Dout is determined based on the lateral displacement X. Specifically, when the vehicle is laterally displaced from the center of the lane to the left, the direction is set as the departure direction Dout (Dout = left), and when the vehicle is laterally displaced from the center of the lane to the right, the direction is changed to the departure direction Dout. (Dout = right).

As described above, the lane departure tendency is determined in step S4.
Subsequently, in step S5, the driver's intention to change lanes is determined. Specifically, 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 S4, it is determined that the driver has intentionally changed the lane, and the departure determination flag Fout is changed to OFF (Fout = OFF). That is, it is changed to the determination result that there is no lane departure tendency.

When the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout obtained in step S4, the departure determination flag Fout is maintained and the departure determination flag Fout is kept ON. (Fout = ON). That is, the determination result that there is a tendency to depart from the lane is maintained.
When the direction indicating switch 20 is not operated, the driver's intention to change 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, when the departure determination flag Fout is ON, sound output or display output is performed as an alarm for avoiding lane departure.
Subsequently, in step S7, deceleration control determination is performed. Specifically, the processing procedure of this determination processing is as shown in FIG.

First, in step S41, the subtraction value obtained by subtracting the lateral displacement limit distance _{X L} from the estimated lateral displacement Xs calculated in step S4 whether (| -X _L | Xs) is deceleration control determining threshold value X _beta or Determine whether or not.
Here, the deceleration control determination threshold value _Xβ is a value set in accordance with the travel lane curvature β, and the relationship is as shown in FIG. 7, for example.

As shown in FIG. 7, when the traveling lane curvature β is small, the deceleration control determination threshold value X _β is a certain large value. When the traveling lane curvature β is greater than a certain value, the traveling lane curvature β Accordingly, the deceleration control determination threshold value _Xβ is in an inversely proportional relationship, and when the traveling lane curvature β further increases, the deceleration control determination threshold value _Xβ becomes a certain small value. Furthermore, the deceleration control determination threshold value _Xβ may be set to a smaller value as the vehicle speed V increases.

In this step S41, when the subtraction value (| Xs | −X _L ) is equal to or greater than the deceleration control determination threshold value X _β , it is determined that the deceleration control is performed, and the subtraction value (| Xs | −X _L ) is If it is less than the deceleration control determination threshold value _Xβ , it is decided not to perform the deceleration control.
Subsequently, in step S42, a deceleration control operation determination flag Fgs is set based on the determination result in step S41. That is, when it is determined in step S41 that deceleration control is to be performed ((| Xs | −X _L ) ≧ X _β ), it is determined that the deceleration control operation determination flag Fgs is set to ON and deceleration control is not performed in step S41. If this occurs ((| Xs | −X _L ) <X _β ), the deceleration control operation determination flag Fgs is turned OFF.

Subsequently, in step S8, a target yaw moment Ms to be given to the vehicle as lane departure avoidance control is calculated.
Specifically, the target yaw moment Ms is calculated by the following equation (4) based on the estimated lateral displacement Xs obtained and lateral displacement limit distance X _L in the step S4.
Ms = K1 · K2 · (| Xs | −X _L ) (4)
Here, K1 and K2 are gains that vary according to the vehicle speed V. FIG. 8 shows an example of the gain K2. As shown in FIG. 8, 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. Thus, the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _L is, target yaw moment Ms becomes larger.

Further, when the departure determination flag Fout is ON, the target yaw moment Ms is calculated by the above equation (4), and when the departure determination flag Fout is OFF, the target yaw moment Ms is set to 0. The target yaw moment Ms is set to a larger value as the deviation from the lane (predetermined reference position) increases.
Further, when the rear vehicle detection flag Fbr set in step S3 (step S22) is 1, that is, when there is a rear vehicle near the host vehicle, the gain Ka is set to the target yaw moment Ms calculated by the equation (4). The value is corrected to the multiplied value (Ms · Ka). In other cases (Fbr = 0), the target yaw moment Ms calculated by the above equation (4) is not corrected.

Here, the gain Ka is a value from 0 to 1 (0 <Ka ≦ 1), and is a value determined according to the relative distance Lbr and the first collision time TTCbr. Specifically, the gain Ka is set to a smaller value as the relative distance Lbr and the first collision time TTCbr become smaller.
Further, when the rear side vehicle detection flag Fbsr set in step S3 (step S24) is 1, that is, when there is a rear side vehicle near the host vehicle, the target yaw moment Ms calculated by the above equation (4). Is multiplied by the gain Kp (Ms · Kp). In other cases (Fbsr = 0), the target yaw moment Ms calculated by the above equation (4) is not corrected.

Here, the gain Kp is a value from 0 to 1 (0 <Kp ≦ 1), and is a value determined according to the relative distance Lbsr and the second collision time TTCbs. Specifically, the gain Kp is set to a smaller value as the relative distance Lbsr and the second collision time TTCbs are smaller.
Therefore, when there is a rear vehicle or a rear side vehicle near the host vehicle, the target yaw moment Ms is corrected to a small value.
Here, FIG. 9 shows an example of a change in the target yaw moment Ms according to the relative distances Lbr and Lbsr. As shown in FIG. 9, when the relative distances Lbr and Lbsr are reduced, the target yaw moment Ms is also reduced stepwise. FIG. 10 shows an example of a change in the target yaw moment Ms according to the collision times TTCbr and TTCbs. As shown in FIG. 10, when the collision times TTCbr and TTCbs are reduced, the target yaw moment Ms is also reduced stepwise.

Therefore, for example, when the relative distances Lbr and Lbsr and the collision times TTCbr and TTCbs are reduced stepwise according to the time T, the target yaw moment Ms is also reduced stepwise as shown in FIG.
Subsequently, in step S9, a deceleration for decelerating the vehicle as lane departure avoidance 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 (5).
Pgf = Kgv · V + Kgx · dx (5)

  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. 12 shows an example of the conversion coefficients Kgv and Kgx. As shown in FIG. 12, for example, the conversion coefficients Kgv and Kgx have large values in the low speed range, and when the vehicle speed V reaches a certain value, the conversion coefficients Kgv and Kgx decrease with the increase in the vehicle speed V and then reach a certain vehicle speed V. It becomes a constant value.

  When the rear vehicle detection flag Fbr set in step S3 (step S22) is 1, that is, when there is a rear vehicle near the host vehicle, the target braking hydraulic pressure Pgf for the front wheels calculated by the above equation (5). Is multiplied by a gain δ (Pgf · δ). In other cases (Fbr = 0), the correction of the target brake hydraulic pressure Pgf for the front wheels calculated by the above equation (5) is not performed. Here, the gain δ is a value between 0 and 1 (0 <δ ≦ 1). Therefore, when there is a rear vehicle near the host vehicle, the target braking hydraulic pressure Pgf for the front wheels is corrected to a small value.

Then, based on the front-wheel target braking hydraulic pressure Pgf calculated in this way, the rear-wheel target braking hydraulic pressure Pgr considering the front-rear distribution is calculated.
Thus, in step S9, deceleration for avoiding deviation (specifically, target braking hydraulic pressures Pgf, Pgr) is obtained.
Subsequently, in step S10, 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 avoiding lane departure. Specifically, it is calculated as follows.

When the departure determination flag Fout is OFF (Fout = OFF), that is, when a determination result that there is no lane departure tendency is obtained, as shown in the following equations (6) and (7), 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 (6)
Psrl = Psrr = Pmr (7)
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.
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.

On the other hand, 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 wheel target A brake fluid pressure difference ΔPsr is calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (8) to (11).
When | Ms | <Ms1, ΔPsf = 0 (8)
ΔPsr = Kbr · Ms / T (9)
When | Ms | ≧ Ms1 ΔPsf = Kbf · (Ms / | Ms |) · (| Ms | −Ms1) / T (10)
ΔPsr = Kbr · (Ms / | Ms |) · Ms1 / T (11)
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. Specifically, the final target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated with reference to the deceleration control operation determination flag Fgs obtained in step S7.

That is, when the departure determination flag Fout is ON (Fout = ON), that is, a determination result that there is a tendency to depart from the lane is obtained, but when the deceleration control operation determination flag Fgs is OFF, that is, only the yaw moment is applied to the vehicle. When acting, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (12).
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
(12)

Further, when the departure determination flag Fout is ON (Fout = ON) and the deceleration control operation determination flag Fgs is ON, that is, when the vehicle is decelerated while the yaw moment is applied to the vehicle, the following equation (13) To calculate the target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel.
Psfl = Pmf + Pgf / 2
Psfr = Pmf + ΔPsf + Pgf / 2
Psrl = Pmr + Pgr / 2
Psrr = Pmr + ΔPsr + Pgr / 2
(13)

  Further, as shown by the equations (12) and (13), the brake 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). 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.

Next, a series of operations will be described.
First, various data are read and the vehicle speed V is calculated (steps S1 and S2).
Subsequently, a vehicle detection flag around the host vehicle is set (step S3). Specifically, when a vehicle behind the vehicle is detected using the vehicle detection threshold and it is determined that there is a vehicle behind the vehicle, the vehicle detection flag Fbr is set to 1 and the vehicle is close to the vehicle. When it is determined that there is no rear vehicle, the rear vehicle detection flag Fbr is set to zero. When the rear side vehicle is detected using the rear side vehicle detection threshold and it is determined that there is a rear side vehicle near the host vehicle, the rear side vehicle detection flag Fbsr is set to 1. If it is determined that there is no rear side vehicle near the host vehicle, the rear measurement vehicle detection flag Fbsr is set to zero. Further, when the vehicle is detected to the side of the own vehicle, the side vehicle detection flag Fsr is set to 1. When the vehicle is not detected to the side of the own vehicle, the side vehicle detection flag Fsr is set to 0. Set.

Subsequently, a lane departure tendency is determined (step S4). Specifically, 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), determines that there is no lane departure tendency. Here, or if there are rear lateral vehicle near the vehicle when there are vehicles on the side of the vehicle, since is set in departure tendency determining threshold value X _L is smaller (X _Ld), Even with a small estimated lateral displacement Xs, it is easy to determine that there is a tendency to depart from the lane, that is, the operation timing of the lane departure control is advanced.

  Further, the departure direction Dout is determined based on the lateral displacement X. Then, the intention of the driver to change the lane is determined based on the departure direction Dout and the direction indicated by the direction switch signal (the blinker lighting side), and the departure determination flag Fout is changed based on the determination (step S5). If the departure determination flag Fout is ON, a warning is output for avoiding lane departure (step S6).

Subsequently, deceleration control determination (setting of the deceleration control operation determination flag Fgs) is performed (step S7).
Subsequently, a target yaw moment Ms to be given to the vehicle as lane departure avoidance control is calculated (step S8). Here, when there is a rear vehicle or a rear side vehicle near the host vehicle (Fbr = 1, Fbsr = 1), the target yaw moment Ms is corrected to a small value.

Subsequently, deceleration (target braking hydraulic pressures Pgf, Pgr) for decelerating the vehicle as lane departure avoidance control is calculated (step S9). Here, when there is a high possibility that the rear vehicle will come into contact with the host vehicle (Fbr = 1), the target braking hydraulic pressures Pgf and Pgr are corrected to small values.
Then, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated based on the departure determination flag Fout and the deceleration control operation determination flag Fgs, and the calculated target braking fluid pressure Psi (i = fl, fr, rl, rr) are output to the brake fluid pressure controller 7 as a brake fluid pressure command value (step S10).
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, the own vehicle shows the deceleration behavior and the turning behavior as the lane departure avoidance behavior.

Here, the operation of the own vehicle will be described with reference to FIGS.
FIG. 13 shows the operation of the host vehicle 100 when the rear vehicle 101 is in the same lane as the host vehicle 100.
As shown in FIG. 13, when the host vehicle 100 tends to depart from the lane, when the rear vehicle 101 is approaching the host vehicle 100, the host vehicle 100 has a deceleration B corrected to a value smaller than a normal value. 100 is decelerated and a yaw moment Ms having a value smaller than a normal value is applied to the host vehicle 100 for a longer time than usual.
By reducing the deceleration in this way, it is possible to prevent the rear vehicle from approaching the host vehicle too much, and by reducing the yaw moment, the behavior of the host vehicle makes the driver of the rear vehicle feel uncomfortable. Can be prevented.

FIG. 14 shows the operation of the host vehicle 100 when the rear side vehicle 101 is in the adjacent lane.
As shown in FIG. 14, when the own vehicle 100 has a tendency to depart from the lane, when the rear side vehicle 101 approaches the own vehicle 100 in the adjacent lane, the yaw moment Ms having a value smaller than the normal value is obtained. Is given to the host vehicle 100 at a timing earlier than usual for a longer time than usual. Thereby, it is possible to prevent the behavior of the host vehicle from giving an uncomfortable feeling to the driver of the rear side vehicle.
Note that deceleration control for avoiding lane departure is performed at a normal operation timing and at a normal size.

FIG. 15 shows the operation of the host vehicle 100 when the side vehicle 101 is in the adjacent lane.
As shown in FIG. 15, when the host vehicle 100 has a tendency to depart from the lane, when the vehicle 101 traveling in the adjacent lane is traveling on the side of the host vehicle 100, the value is smaller than the normal value. Is given to the host vehicle 100 at a timing earlier than usual. Thereby, it is possible to prevent the behavior of the host vehicle from giving an uncomfortable feeling to the driver of the rear side vehicle.
Note that deceleration control for avoiding lane departure is usually performed at a normal operation timing and at a normal size.

The embodiments of the present invention have been described above. However, the present invention is not limited to being realized as the above-described embodiment.
That is, in the embodiment, the case where the yaw moment applied to the host vehicle is reduced has been described. However, it is not limited to this. That is, for example, the yaw angular acceleration or yaw rate when applying a yaw moment to the host vehicle may be reduced. For example, since the initial yaw motion of the host vehicle is suppressed by reducing the yaw angular acceleration, it is possible to more effectively prevent the driver of the rear vehicle from feeling uncomfortable. If the yaw angular acceleration and yaw rate are reduced in this way, the time until the host vehicle completes avoidance of departure becomes longer.

  In the description of the embodiment, the process of step S4 by the braking / driving force control unit 8 realizes a lane departure tendency determining means for determining the departure tendency of the host vehicle with respect to the traveling lane, and the braking / driving force control unit 8 The processing of step S7 to step S10 according to the above embodiment realizes a departure avoidance control means that, when the lane departure tendency determination means determines that there is a departure tendency, controls the own vehicle to avoid departure of the own vehicle from the traveling lane. The processing of steps S21 to S24 (processing of step S3) by the rear obstacle detection radar 31, the rear obstacle detection radars 32 and 33, and the braking / driving force control unit 8 is the rear of the host vehicle. A vehicle detection means for detecting the other vehicle is realized, and the step by the braking / driving force control unit 8 is realized. The correction process in the processes in steps S35 to S35 and the processes in steps S8 and S9 suppresses and controls the control of the departure avoidance control means when the rear vehicle detection means detects another vehicle behind the host vehicle. A control correction means for performing at least one of increasing the operation timing is realized.

  Further, in the present invention, the term “rear” includes the rear side part of the host vehicle 100 and both sides behind the host vehicle 100 (for example, adjacent lane portions), as indicated by a dotted line A in FIG. In other words, an object of the present invention is to cause the driver of another vehicle having the own vehicle 100 within the viewing range to feel the vehicle behavior strange by operating the lane departure avoidance control on the own vehicle. It is because it prevents.

It is a schematic block diagram which shows embodiment of the vehicle carrying the lane departure prevention apparatus of this invention. It is a flowchart which shows the processing content of the braking / driving force control unit which comprises the said lane departure prevention apparatus. It is a flowchart which shows the processing content of the setting of the vehicle detection flag around the own vehicle in the said braking / driving force control unit. It is a flowchart which shows the processing content of the deviation tendency determination of the said braking / driving force control unit. It is the figure used for description of yaw angle (phi) read by the various data reading process of the said braking / driving force control unit, lateral displacement X0, etc. FIG. It is a flowchart which shows the processing content of the deceleration control determination of the said braking / driving force control unit. FIG. 6 is a characteristic diagram showing a relationship between a deceleration control determination threshold value _Xβ and a travel lane curvature β. FIG. 6 is a characteristic diagram showing a relationship between a proportional coefficient K2 and a vehicle speed V. It is a characteristic view which shows an example of the change of the target yaw moment Ms according to relative distance Lbr and Lbsr. An example of the change of the target yaw moment Ms according to the collision times TTCbr and TTCbs will be shown. It is a characteristic view showing an example of change of target yaw moment Ms when relative distances Lbr and Lbsr and collision times TTCbr and TTCbs become smaller with time. FIG. 6 is a characteristic diagram showing the relationship between conversion coefficients Kgv, Kgx and vehicle speed V. It is a figure which shows the operation | movement of the said own vehicle 100 when the back vehicle 101 exists in the same lane as the own vehicle 100. FIG. It is a figure which shows operation | movement of the said own vehicle 100 when the rear side vehicle 101 exists in an adjacent lane. It is a figure which shows operation | movement of the said own vehicle 100 when the side vehicle 101 exists in an adjacent lane. It is the figure used for description of the definition of "back" in the present invention.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control unit 8 Braking / driving force control unit 9 Engine 12 Drive torque control unit 13 Imaging unit 14 Navigation device 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 22FL to 22RR Wheel speed sensor 31 Rear obstacle detection radar 32, 33 Rear side obstacle detection radar 34, 35 Side obstacle detection radar

Claims (5)

Lane departure tendency determination means for determining the departure tendency of the host vehicle with respect to the traveling lane;
When the lane departure tendency determining means determines that there is a departure tendency, a departure avoidance control means for giving a yaw moment to the own vehicle and avoiding the departure of the own vehicle with respect to the traveling lane;
A rear vehicle detecting means for detecting other vehicles behind the host vehicle;
Control correcting means for suppressing the yaw moment given by the departure avoidance control means and extending the time for giving the yaw moment when the rear vehicle detecting means detects another vehicle behind the host vehicle;
A lane departure prevention apparatus comprising:   The control correction means suppresses the control of the departure avoidance control means by performing at least one of reducing a yaw angular acceleration and a yaw rate when applying the yaw moment. The lane departure prevention apparatus according to claim 1.   When the time obtained by dividing the inter-vehicle distance between the host vehicle and the rear vehicle by the relative distance between the host vehicle and the rear vehicle is smaller than the first threshold, The lane departure prevention apparatus according to claim 1, wherein the lane departure prevention device is detected.   The rear vehicle detection means is configured such that, even when the time obtained by dividing the inter-vehicle distance between the host vehicle and the rear vehicle by the relative distance between the host vehicle and the rear vehicle is long, the inter-vehicle distance exceeds the second threshold value. The lane departure prevention apparatus according to claim 1, wherein the other vehicle is detected when the value is smaller.   5. The control correction unit according to claim 1, wherein the control correction unit suppresses the yaw moment and makes a timing for applying the yaw moment faster than when the yaw moment is not suppressed. The lane departure prevention apparatus described.

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