JP2008021012A - Lane departure prevention apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure yaw moment required for lane departure prevention of one's own vehicle. <P>SOLUTION: This lane departure prevention apparatus acquires the shortfall of the control amount of lane departure prevention control (Step S3), changes control completion timing of the lane departure prevention control based on the shortfall (Step S5), determines a departure tendency of the own vehicle with respect to the cruising lane (Step S4 and Step S8). As a result, when there is a lane departure tendency, lane departure prevention control for preventing the departure of the own vehicle with respect to the cruising is performed by cruise control, and completes the lane departure prevention control when it the changed control completion timing(Step S9 to S11) is reached. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lane departure prevention apparatus for preventing a departure when a host vehicle is about to depart from a traveling lane.

As conventional lane departure prevention control, when there is a possibility that the host vehicle departs 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 one that prevents deviation (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-112540

However, because the yaw moment (target yaw moment) to be given to the host vehicle is calculated as lane departure prevention control based on the vehicle specifications, vehicle speed, lateral position of the host vehicle with respect to the driving lane, etc., the friction resistance of the brake pad is reduced. There is a problem that the calculated desired yaw moment cannot be applied to the host vehicle when the vehicle is running.
In order to compensate for the shortage of the yaw moment, it is conceivable to change the control amount by feedback control, etc., but the lateral deviation of the own vehicle is somewhat large reflecting the driver's intention to change lanes etc. Then, in the lane departure prevention control device that cancels the lane departure prevention control, there is a problem that the lane departure prevention control is canceled before the effect of changing the control amount is obtained.
An object of the present invention is to secure a yaw moment necessary for preventing lane departure of the host vehicle.

  In order to solve the above-mentioned problems, the present invention provides a lane departure tendency determination unit that determines a departure tendency of the host vehicle with respect to a traveling lane, and the vehicle travels by traveling control when the lane departure tendency determination unit determines that there is a departure tendency. A lane departure prevention control for preventing the departure of the host vehicle from the lane, and a control means for ending the lane departure prevention control when a predetermined control end timing is reached, and control of the lane departure prevention control by the control means A control shortage acquisition unit that acquires a shortage of the amount; and a control timing change unit that changes the predetermined control end timing based on the shortage acquired by the control shortage acquisition unit. Accordingly, the control end timing of the lane departure prevention control is changed based on the shortage of the control amount of the lane departure prevention control.

  According to the present invention, since the control end timing of the lane departure prevention control is changed based on the insufficient amount of the lane departure prevention control, when the control amount of the lane departure prevention control is to be compensated Thus, it is possible to prevent the lane departure prevention control from being canceled due to the control end timing, and to secure a control amount necessary for preventing the lane departure of the host vehicle.

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.
(Constitution)
The present 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 individually controls the braking fluid pressure of each wheel cylinder 6FL-6RR. It is also possible to control it.

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. When a drive torque command value is input from the braking / driving force control unit 8, the drive torque command unit 12 The drive wheel torque is controlled according to the 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. The imaging unit 13 is installed in the front part of the vehicle.

  The imaging unit 13 detects a lane marker such as a white line from a captured image in front of the host vehicle, and detects a traveling lane based on the detected lane marker. Further, the imaging unit 13 determines, based on the detected travel lane, an angle (yaw angle) φ between the travel lane of the host vehicle and the longitudinal axis of the host vehicle, a lateral displacement X from the center of the travel lane, and a travel lane curvature. β and the like are calculated. The imaging unit 13 outputs the calculated yaw angle φ, lateral displacement X, travel lane curvature β, and the like to the braking / driving force control unit 8.

In the present invention, the lane marker may be detected by detection means other than image processing. For example, the lane marker may be detected by a plurality of infrared sensors attached to the front of the vehicle, and the traveling lane may be detected based on the detection result.
Further, the present invention is not limited to the configuration in which the traveling lane is determined based on the white line. In other words, if there is no white line (lane marker) on the road to recognize the driving lane, the information on the road shape and surrounding environment obtained by image processing and various sensors, the driving range suitable for driving and driving A person may estimate the travel range where the vehicle should travel and determine the travel lane. For example, when there is no white line on the runway and both sides of the road are separated, the asphalt portion of the runway is determined as the travel lane. Moreover, what is necessary is just to determine a driving lane in consideration of the information, when there is 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 ′ (= dφ / dt) to the braking / driving force control unit 8 together with the road information. Here, as the road information, there is road type information indicating a road type such as the number of lanes, a general road, or a highway.

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

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

  When the detected vehicle traveling state data has left and right directions, the right direction is the positive direction in all cases. That is, the yaw rate φ ′, the lateral acceleration Xg, and the yaw angle φ are positive values when turning right, and the lateral displacement X is a positive value when deviating from the center of the traveling lane to the right. The longitudinal acceleration Yg takes a positive value during acceleration and takes a negative value during deceleration.

Next, calculation processing performed by the braking / driving force control unit 8 will be described.
FIG. 2 shows a calculation processing procedure performed by the braking / driving force control unit 8. 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 calculation process is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.

  As shown in FIG. 2, when the process is started, first, in step S1, various data are read from each sensor, controller, and control unit. Specifically, the road surface μ obtained by the road surface μ detection device 23, the longitudinal acceleration Yg, the lateral acceleration Xg, the yaw rate φ ′ and the road information obtained by the navigation device 14, each wheel speed Vwi, the steering angle detected by each sensor. δ, accelerator opening θt, master cylinder hydraulic pressures Pmf, Pmr, direction switch signal, drive torque Tw from drive torque control unit 12, yaw angle φ, lateral displacement X, and travel lane curvature β are read from 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. In addition, a value used for navigation information in the navigation device 14 may be used as the vehicle speed V.
Further, as shown in the following equation (2), the vehicle speed V at the time of the previous process is set to the previous vehicle speed V _PAST .
V _PAST = V ( _Vehicle speed at the previous processing) (2)

Subsequently, in step S3, an insufficient yaw moment (insufficient control amount) is calculated.
In the present embodiment, in the lane departure prevention control, when the host vehicle tends to depart from the traveling lane, the host vehicle travels by giving a predetermined yaw moment (predetermined lane departure prevention control amount) to the host vehicle. Avoiding departure from the lane.
In the lane departure prevention control of the present embodiment, it is assumed that the processing routine of the lane departure prevention control (the processing routine of FIG. 2) is executed a plurality of times before completion of lane departure avoidance, that is, the yaw moment (specifically Specifically, it is assumed that the target yaw moment Ms) is continuously and sequentially applied to the host vehicle to avoid lane departure of the host vehicle.

In this step S3, the deficiency (deficiency) of the yaw moment, which is the control amount of the lane departure prevention control as described above, is calculated (estimated).
Specifically, first, the target yaw moment Ms calculated in the previous process (calculated in step S9 described later) is set as the previously calculated target yaw moment Msb by the following equation (3).
Msb = Ms (3)
Subsequently, the actual yaw moment Msr generated by the previous process is calculated based on the vehicle speed V. That is, the actual yaw moment Msr is the yaw moment actually generated in the host vehicle when the target yaw moment Ms calculated in the previous process is applied to the host vehicle as lane departure prevention control.

Specifically, first, the deceleration ΔV is calculated by the following equation (4) using the previous vehicle speed V _PAST and the current vehicle speed V calculated in step S2.
ΔV = (V−V _PAST ) / ΔT (4)
Here, ΔT is a one-step processing time for executing the processing of FIG.
Subsequently, the deceleration ΔVc for the lane departure prevention control is calculated by the following equation (5) using the deceleration ΔV calculated by the equation (4).
ΔVc = ΔV−ΔVd (5)
Here, ΔVd is a deceleration based on deceleration by the driver's accelerator operation and brake operation, vehicle specifications, and travel resistance. Here, ΔVd can be obtained from the map corresponding to deceleration by the accelerator operation and the brake operation, or ΔVd can be calculated based on the engine speed and the accelerator opening.

Then, the actual yaw moment Msr is calculated by the following equation (6) using the deceleration ΔVc for the lane departure prevention control calculated by the equation (5).
Msr = A · ΔVc · L _TR / 2 (6)
Here, A is the vehicle weight, and L is the tread length. In this manner, the actual yaw moment Msr generated by the previous process is calculated based on the vehicle speed V.
Then, as a difference value between the actual yaw moment Msr calculated by the above (6) and the previously calculated target yaw moment Msb by the above expression (3), the insufficient yaw moment ΔMs is calculated by the following expression (7).
ΔMs = Msb−Msr (7)

Subsequently, in step S4, a lane departure tendency is determined. Specifically, using the yaw angle φ, travel lane curvature β and current vehicle lateral displacement X (X0) obtained in step S1, and vehicle speed (current vehicle speed) V obtained in step S2, first, A future estimated lateral displacement Xs is calculated by the following equation (8) (see FIG. 3).
Xs = Tt · V · (φ + Tt · V · β) + X (8)
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 (8), the estimated lateral displacement Xs increases as the yaw angle φ increases, for example, when attention is paid to the yaw angle φ.

Then, such estimated lateral displacement Xs with a predetermined departure-tendency threshold value (lateral displacement limit distance) is compared with the X _L, it determines the lane departure tendency. 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, departure-tendency threshold value X _L is a value indicating the position of the travel path of the border, for example, is calculated by the following equation (9) (see FIG. 3).
X _L = (L−H) / 2 (9)
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.

In FIG. 3, departure-tendency threshold value X _L has been set within the travel lane of the vehicle, the present invention is not limited thereto, it may be set outside of the travel lane. Also, the departure tendency determination threshold value X _L is not limited to that in which the departure tendency is determined before the own vehicle deviates from the traveling lane, but for example, the departure tendency is determined after at least one of the wheels has deviated from the lane. May be set.
Here, if the following expression (10) holds, it is determined that there is a tendency to depart from the lane, and the departure determination flag Fout is turned ON (Fout = ON).
| Xs | ≧ X _L (10)
On the other hand, if the following equation (11) holds, it is determined that there is no tendency to depart from the lane, and the departure determination flag Fout is turned off (Fout = OFF).
_{| Xs | <X L ··· (} 11)

Here, 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).
Subsequently, in step S5, the control end timing of the lane departure prevention control is set (changed). Specifically, the control timing is set (changed) according to the insufficient yaw moment ΔMs calculated in step S3. To do. This process is executed (validated) when the departure determination flag Fout set in step S4 (more specifically, finally set in step S6 described later) is ON.
Here, the index of the control end timing is time (control end time) and position (control end position (lateral position)), the control end time is set as T _END , and the control end position is set as X _END .

Figure 4 shows an example of the relationship between yaw moment ΔMs shortfall the control end time T _END.
As shown in FIG. 4, when the insufficient yaw moment ΔMs is small, the control end time T _END becomes a certain small value, and when the insufficient yaw moment ΔMs exceeds a certain value, the insufficient yaw moment ΔMs is obtained. The control end time T _END also increases in proportion, and when the insufficient yaw moment ΔMs further increases, the control end time T _END becomes a certain large value.

Figure 5 shows an example of the relationship between the yaw moment ΔMs shortfall and the control end position X _END.
As shown in FIG. 5, when the yaw moment ΔMs shortfall is small, the control end position X _END becomes constant small value in becomes greater than a certain value yaw moment ΔMs shortfall, the deficiency of the yaw moment ΔMs The control end position X _END also increases in proportion, and when the insufficient yaw moment ΔMs further increases, the control end position X _END becomes a certain large value.

For example, the case where the deficient yaw moment ΔMs is 0 or a value close to 0 is a case where the actual yaw moment Msr matches or substantially matches the target yaw moment Msb, that is, desired by lane departure prevention control. a case where the yaw moment of the (ideal) is generated in the subject vehicle, the control end time T _END and control end position X _END of this time, the impression that the lane departure prevention control is too long the driver The lane departure prevention control is set to a value that does not bother the driver who intends to change the lane or give the driver a lane change. That is, the control end time T _END and the control end position X _END are changed according to the deficient yaw moment ΔMs with reference to the values set in this way.

With reference to FIGS. 4 and 5 as described above, the control end time T _END and the control end position X _END corresponding to the insufficient yaw moment ΔMs are set.
Subsequently, in step S6, the driver's intention to change lanes is determined. Specifically, the driver's intention to change the lane is determined as follows based on the direction switch signal and the steering angle δ obtained in step S1.

If the direction indicated by the direction switch signal (the blinker lighting side) is the same as the direction indicated by the departure direction Dout obtained in step S4, it is determined that the driver has intentionally changed the lane, and the departure determination flag Fout is changed to OFF (Fout = OFF). That is, it is changed to the determination result that there is no lane departure tendency.
When the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout obtained in step S4, the departure determination flag Fout is maintained and the departure determination flag Fout is kept ON. (Fout = ON). That is, the determination result that there is a tendency to depart from the lane is maintained.

Thus, when the departure determination flag Fout is ON, the departure determination flag Fout is maintained ON when the driver has not intentionally changed the lane.
Subsequently, in step S7, when the departure determination flag Fout is ON, sound output or display output is performed as an alarm for avoiding 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 S8, it is determined whether or not deceleration control for decelerating the host vehicle (hereinafter referred to as deceleration control for lane departure prevention) is performed as lane departure prevention control. Specifically, the subtraction value obtained by subtracting the lateral displacement limit distance X _L from the estimated lateral displacement Xs calculated in step S4 whether (| | Xs -X _L) is deceleration control determining threshold value X _beta or Determine whether.
Here, the deceleration control determination threshold value _Xβ is a value set according to the travel lane curvature β, and the relationship is as shown in FIG. 6, for example. As shown in FIG. 6, when the traveling lane curvature β is small, the deceleration control determination threshold value X _β becomes a certain large value, and when the traveling lane curvature β exceeds a certain value, the traveling lane curvature β increases. On the other hand, when the deceleration control determination threshold value _Xβ decreases and the travel lane curvature β further increases, the deceleration control determination threshold value _Xβ becomes a certain small value.

When the subtraction value (| Xs | −X _L ) is equal to or greater than the deceleration control determination threshold value X _β (| Xs | −X _L ≧ X _β ), it is determined that the deceleration control is performed, and the deceleration control operation is performed. When the determination flag Fgs is turned ON and the subtraction value (| Xs | −X _L ) is less than the deceleration control determination threshold value X _β (| Xs | −X _L <X _β ), the determination that the deceleration control is not performed is made. And the deceleration control operation determination flag Fgs is turned OFF.

In the relationship with the departure flag Fout is set at step S4, when the estimated lateral displacement Xs in the step S4 is equal to or higher than the departure-tendency threshold value _{X L (| Xs | ≧ X} L), the departure flag and setting the Fout to oN, the subtraction value (| Xs | -X _L) is the deceleration control when the determination at or above the threshold X _beta for, on the relationship between the setting the deceleration control flag Fgs to oN Even if the departure determination flag Fout is set to ON, the setting is made after the deceleration control operation determination flag Fgs is set to ON. That is, in relation to the application of yaw moment to the host vehicle that is performed when a deviation determination flag Fout, which will be described later, is turned on, the yaw moment is applied after the deceleration control of the host vehicle is performed.

Subsequently, in step S9, a target yaw moment Ms is calculated.
Specifically, step S4 obtained in the estimated lateral displacement Xs and lateral displacement limit distance X _L and the reference target yaw moment by the following equation (12) based on Ms0 (the yaw moment that does not take into account the shortfall) calculate.
Ms0 = K1 · K2 · (| Xs | −X _L ) (12)
Here, K1 is a proportional gain determined from vehicle specifications, and K2 is a gain that varies according to the vehicle speed V. FIG. 7 shows an example of the gain K2. As shown in FIG. 7, in the low speed range, the gain K2 becomes a certain large value. When the vehicle speed V becomes larger than a certain value, the gain K2 decreases with respect to the increase in the vehicle speed V, and then reaches a certain vehicle speed V. When reaching, the gain K2 becomes a certain small value.

According to this equation (12), the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _L is, the target yaw moment Ms0 criteria increases.
Then, as an addition value of the reference yaw moment Ms0 calculated by the equation (12) and the insufficient yaw moment ΔMs calculated by the step S3 (the equation (7)), the target yaw moment is calculated by the following equation (13). (Final target yaw moment to be applied) Ms is calculated.
Ms = Ms0 + ΔMs (13)
Here, 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 S10, the deceleration in the lane departure prevention deceleration 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. With respect to the target braking hydraulic pressure Pgf for the front wheels, the estimated lateral displacement Xs and lateral displacement limit distance X _L calculated in step S4 and the deceleration control determination threshold value X _β obtained in step S8 are described below. It calculates with (14) Formula.
Pgf = Kgv · Kgx · (| Xs | −X _L −X _β ) (14)

  Here, Kgv is a conversion coefficient set according to the vehicle speed V, and Kgx is a conversion coefficient determined by vehicle specifications. FIG. 8 shows an example of the conversion coefficient Kgv. As shown in FIG. 8, in the low speed range, the conversion coefficient Kgv becomes a certain small value. When the vehicle speed V becomes larger than a certain value, the conversion coefficient Kgv increases with the vehicle speed V, and then reaches a certain vehicle speed V. The conversion coefficient Kgv is a certain large value.

Further, based on the target braking hydraulic pressure Pgf for the front wheels calculated as described above, the target braking hydraulic pressure Pgr for the rear wheels considering the front-rear distribution is calculated.
Thus, in step S10, deceleration (specifically, target braking hydraulic pressures Pgf, Pgr) in the deceleration control for preventing lane departure is obtained.
Subsequently, in step S11, 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.

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 formulas (15) and (16), the target brake fluid pressure Psi (i = fl, fr, rl, rr) are set to the brake fluid pressures Pmf, Pmr.
Psfl = Psfr = Pmf (15)
Psrl = Psrr = Pmr (16)
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.

On the other hand, when the departure determination flag Fout is ON, that is, when a determination result that there is a lane departure tendency is obtained, first, based on the target yaw moment Ms, the front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr are set. calculate. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (17) to (20).
If | Ms | <Ms1, ΔPsf = 0 (17)
ΔPsr = Kbr · Ms / L _TR (18)
When | Ms | ≧ Ms1 ΔPsf = Kbf · (Ms / | Ms |) · (| Ms | −Ms1) / L _TR (19)
ΔPsr = Kbr · (Ms / | Ms |) · Ms1 / L _TR (20)
Here, Ms1 represents a setting threshold value. The tread _LTR is set to the same value before and after for convenience. 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 on 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.

  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 set in step S8. .

That is, when the departure determination flag Fout is ON, that is, a determination result that there is a lane departure tendency is obtained, but when the deceleration control operation determination flag Fgs is OFF, that is, when only the yaw moment is applied to the vehicle, The target braking hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (21).
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (21)

When the departure determination flag Fout is ON and the deceleration control operation determination flag Fgs is ON, that is, when the vehicle is decelerated while giving a yaw moment to the vehicle, the target of each wheel is expressed by the following equation (22). The brake fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pmf + Pgf / 2
Psfr = Pmf + ΔPsf + Pgf / 2
Psrl = Pmr + Pgr / 2
Psrr = Pmr + ΔPsr + Pgr / 2
(22)

  Further, as shown in the equations (21) and (22), 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 fluid pressure Psi (i = fl, fr, rl, rr) calculated for each wheel in this way as a braking fluid pressure command value to the braking fluid pressure control unit 7. Output.

It should be noted that the target braking hydraulic pressures and the like of the wheels shown in the equations (17) to (22) are when the departure direction Dout is left (Dout = left), that is, when there is a tendency to depart from the left lane. However, when the departure direction Dout is right (Dout = right), that is, when there is a lane departure tendency with respect to the right lane, the expressions corresponding to the expressions (17) to (22) are described. Omitted. When the departure direction Dout is right, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel corresponding to the equation (21) is calculated by the following equation (23).
Psfl = Pmf + ΔPsf
Psfr = Pmf
Psrl = Pmr + ΔPsr
Psrr = Pmr
... (23)

Further, although the control end timing of the lane departure prevention control is set (changed) in step S5, the lapse of the lane departure prevention control at the set control end timing is the elapsed time from the start of the lane departure prevention control. _{Becomes the} control end time T _END , or when the lateral position (actual lateral position X or estimated lateral displacement Xs) of the host vehicle becomes the control end position X _END during the lane departure prevention control, the departure determination flag Fout is set. By setting (changing) to OFF, the lane departure prevention control is terminated.

(Operation)
The operation is as follows.
While the vehicle is running, various data are read (step S1), the vehicle speed V is calculated, and the previous vehicle speed V _PAST is set (step S2). Then, the yaw moment ΔMs for the shortage is calculated using the vehicle speed V, the previous vehicle speed V _PAST, etc. (step S3), and the control end timing of the lane departure prevention control is calculated based on the calculated shortage yaw moment ΔMs. Specifically, the control end time _TEND and the control end position _XEND are set (changed) (step S5).

  Further, a future estimated lateral displacement (deviation estimated value) Xs is calculated, and a lane departure tendency is determined (setting of the departure determination flag Fout) based on the calculated estimated lateral displacement Xs (step S4). The determination result of the lane departure tendency (deviation determination flag Fout) is corrected based on the driver's intention to change the lane (step S6). Based on the determination result of the lane departure tendency, a warning is output (step S7).

  In addition, a deceleration control operation determination flag Fgs is set based on the estimated lateral displacement Xs (step S8), the target yaw moment Ms to be given to the vehicle as the lane departure prevention control, and the lane departure prevention deceleration control. Deceleration (target braking hydraulic pressures Pgf, Pgr) is calculated (steps S9 and S10). Here, the target yaw moment Ms is a value obtained by adding the insufficient yaw moment ΔMs to the reference target yaw moment Ms0, and is a value obtained by compensating the insufficient yaw moment ΔMs.

Then, based on the states of the departure determination flag Fout and the deceleration control operation determination flag Fgs, the target brake hydraulic pressure Psi (i = fl, i) of each wheel based on the target yaw moment Ms and the deceleration (target brake hydraulic pressure Pgf, Pgr). fr, rl, rr) is calculated, and the calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is output to the brake fluid pressure controller 7 (step S11). Thereby, a yaw moment is given to the own vehicle according to the lane departure tendency of the own vehicle, and the own vehicle is decelerated depending on the case. The elapsed time from the start of control of the lane departure prevention control becomes the control end time _TEND , or the lateral position (actual lateral position X or estimated lateral displacement Xs) of the host vehicle during the lane departure prevention control is the control end position. when or become X _END, the lane departure prevention control is terminated. That is, if the condition for the control end timing is satisfied, the lane departure prevention control ends (forcedly) regardless of the lane departure tendency.

(Function and effect)
The action and effect are as follows.
As described above, based on the deficiency (insufficient amount) ΔMs of the yaw moment that is the control amount of the lane departure prevention control, the control end time T _END that defines the control end timing of the lane departure prevention control and the control end position X _END is set. At this time, the control end time T _END and the control end position X _END are increased as the insufficient yaw moment ΔMs increases.

For example, Figure 9 shows the relationship between yaw moment ΔMs shortfall which is a difference value between the actual yaw moment Msr and the previously calculated target yaw moment Msb and the control end position X _END. As shown in FIG. 9, the control end position X _END increases as the deficient yaw moment ΔMs increases (positioned more outward than the travel lane on which the host vehicle is traveling).

Thus, by setting the control end time T _END and the control end position X _END based on the deficiency (insufficient amount) ΔMs of the yaw moment that is the control amount of the line departure prevention control, the lane departure prevention control can be performed. When trying to compensate for the deficiency of the yaw moment, that is, when the target yaw moment Ms compensated for the deficiency of the yaw moment ΔMs is applied to the host vehicle, the lane departure prevention control is performed at the control end timing. It is possible to prevent the vehicle from being released and to secure a yaw moment necessary for preventing the vehicle from departing from the lane.

Furthermore, since the control end time T _END and the control end position X _END are increased as the insufficient yaw moment ΔMs increases, the control end timing is delayed accordingly even when the insufficient yaw moment ΔMs is large. be able to.
In addition, the said embodiment can also be implement | achieved by the following structures.

  That is, in the embodiment, the control end timing index is the time (control end time) and the position (control end position (lateral position)), but the control end timing index is any of them. Also good. The control end timing index is another value such as the total control amount (control amount integrated value) from the start of control of the lane departure prevention control or the yaw angle of the host vehicle with respect to the traveling lane during the lane departure prevention control. May be. For example, when the index of the control end timing is the yaw angle, an arbitrary yaw angle having an inclination inside the traveling lane in which the host vehicle is traveling is set as the yaw angle that defines the control end timing.

  In the embodiment, the deficient yaw moment ΔMs is calculated (directly calculated) as the difference value between the actual yaw moment Msr and the target yaw moment Msb (formula (7)). On the other hand, the yaw moment ΔMs for the shortage is calculated (estimated) based on the temperature (or temperature history) of the brake device such as the brake pad (or brake shoe), the usage frequency, or the vehicle state such as the vehicle weight. ). Since the temperature of the brake device such as the brake pad (or brake shoe) affects the braking force and thus the actual yaw moment Msr, the temperature of the brake device such as the brake pad (or brake shoe) also The insufficient yaw moment ΔMs can be calculated (estimated). In this case, for example, a relationship between the temperature of the brake device and an index indicating a decrease in braking force is stored in advance as a map, and a device for detecting or estimating the temperature of the brake device is further provided. Then, a deficiency yaw moment is calculated (estimated) based on an index corresponding to the temperature of the brake device. Also, instead of calculating the deficient yaw moment based on the index, when the index exceeds a predetermined threshold value, the difference value between the actual yaw moment Msr and the target yaw moment Msb is calculated. May be. Further, the shortage yaw moment ΔMs can also be calculated (estimated) based on the external traveling environment of the vehicle, such as the weather and the outside temperature, without being limited to the state of the vehicle.

Further, in the embodiment, the actual yaw moment Msr is calculated based on the vehicle speed V (the above equations (4) to (6)). On the other hand, the actual yaw moment Msr can also be calculated based on other values such as the yaw rate φ ′.
In the description of the above embodiment, the processing of step S4 and step S8 of 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 The processing of step S9 to step S11 of the control unit 8 performs lane departure prevention control for preventing deviation of the own vehicle from the traveling lane by traveling control when the lane departure tendency determining means determines that there is a departure tendency. The control means for ending the lane departure prevention control is realized when the predetermined control end timing is reached, and the processing of step S3 of the braking / driving force control unit 8 is the control of the lane departure prevention control by the control means. A control deficient amount acquisition means for acquiring a deficient amount is realized, and the braking / driving force control unit 8 Processing in step S5, based on the shortage of the control insufficient amount acquisition unit has acquired, and realizes the control timing changing means for changing the predetermined control termination timing.

It is a schematic structure figure showing a vehicle of an embodiment of the present invention. It is a flowchart which shows the processing content of the control unit of the lane departure prevention apparatus of a vehicle. 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 a relationship between deficiency of the yaw moment ΔMs and the control end time T _END. It is a characteristic diagram showing a relationship between deficiency of the yaw moment ΔMs and the control end position X _END. FIG. 6 is a characteristic diagram showing a relationship between a travel lane curvature β and a deceleration control determination threshold value _Xβ . 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 the vehicle speed V and the conversion factor Kgv. It is the figure used for description of the effect | action and effect in 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, 17 master cylinder pressure sensor, 18 accelerator opening sensor, 19 steering angle sensor, 22FL-22RR Wheel speed sensor

Claims (6)

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, the lane departure prevention control for preventing the departure of the host vehicle from the traveling lane by running control is performed, and when the predetermined control end timing is reached, the lane departure Control means for terminating prevention control;
An insufficient control amount acquisition means for acquiring an insufficient amount of control amount of the lane departure prevention control by the control means;
Control timing changing means for changing the predetermined control end timing based on the insufficient quantity acquired by the control insufficient quantity acquiring means;
A lane departure prevention apparatus comprising:   2. The lane departure prevention apparatus according to claim 1, wherein the control timing changing unit changes the predetermined control end timing to be delayed as the shortage amount increases. The lane departure prevention control is to prevent the departure of the vehicle from the traveling lane by giving a yaw moment to the vehicle.
The control deficient amount acquisition means controls the control means based on a difference between a target yaw moment applied to the host vehicle as the control amount by the control means and a yaw moment actually generated on the host vehicle by the application of the target yaw moment. The lane departure prevention apparatus according to claim 1, wherein a deficiency amount is acquired.   The said control shortage amount acquisition means estimates the shortage amount of the said control amount of the said control means based on at least any one of the external running environment of the own vehicle, and the own vehicle state. 4. The lane departure prevention apparatus according to any one of items 3.   The predetermined control end timing includes an execution continuation time of the lane departure prevention control, a lateral position of the host vehicle with respect to a traveling lane during the lane departure prevention control, a control amount integrated value from the start of the control of the lane departure prevention control, and The lane departure prevention apparatus according to any one of claims 1 to 4, wherein at least one of the yaw angles of the host vehicle with respect to the traveling lane during the lane departure prevention control is used as an index.   When the host vehicle tends to deviate from the traveling lane, lane departure prevention control is performed to prevent the departure of the host vehicle from the traveling lane, and an insufficient amount of control amount of the lane departure prevention control is acquired. The lane departure prevention apparatus according to claim 1, wherein the control end timing of the lane departure prevention control is changed.

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