JP4496758B2 - Lane departure prevention device - Google Patents

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 a conventional lane departure prevention device, when the host vehicle may deviate from the driving lane, the vehicle deviates from the driving lane by giving a yaw moment to the host vehicle by controlling the braking force to the wheels. In addition, there is a device for notifying the driver that the host vehicle may deviate from the traveling lane by applying the yaw moment (see, for example, Patent Document 1).
JP 2000-33860 A

In a conventional lane departure prevention apparatus, the possibility of lane departure is estimated based on information from a sensor such as a camera, and a yaw moment is applied to the host vehicle based on the estimated departure amount.
For this reason, even when the driver operates the steering wheel and the steering wheel steering angle is input, the yaw moment based on the deviation estimation amount may be applied to the vehicle. In this case, the vehicle exhibits a vehicle behavior different from the operation of the steering wheel, which gives the driver a feeling of strangeness.

Further, it is conceivable that by performing deceleration control, it is possible to prevent lane departure or to effectively control lane departure by the yaw moment. In this case, it is conceivable to operate such deceleration control based on information from a sensor such as a camera. However, if the deceleration control is operated based on information from a sensor such as a camera, the operation may be contrary to the driver's intention, and the driver may feel uncomfortable.
Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a lane departure prevention device that realizes lane departure control without causing the driver to feel uncomfortable.

In order to solve the above-described problem, the lane departure prevention apparatus according to the present invention sets the yaw moment sharing amount and the deceleration sharing amount based on the tendency of the vehicle to deviate from the traveling lane , and based on the yaw moment sharing amount. Calculating the target yaw moment to avoid deviation from the driving lane of the host vehicle, calculating the deceleration control amount based on the deceleration sharing amount, and detecting the departure tendency, the target yaw moment and the deceleration control amount Then, the braking force of each wheel is controlled by the braking force control means, and the control content of the braking force control means is changed based on the steering state.
The lane departure prevention apparatus according to the present invention controls the left and right wheels by adjusting the braking force of the left and right wheels so that the vehicle is given a yaw moment in a direction to avoid lane departure based on the target yaw moment. Generates a power difference and controls the braking force of each wheel to adjust the braking force of the left and right wheels so that the host vehicle decelerates based on the deceleration control amount so as to generate equal braking force on the left and right wheels. To do.
Further, the lane departure prevention apparatus according to the present invention reduces the deceleration control amount by changing the control content of the braking force control means when the steering speed as the steering state is larger than a predetermined threshold value.

According to the present invention, when the steering speed as the steering state is larger than the predetermined threshold value, the vehicle can be smoothly operated by the driver by reducing the deceleration control amount, and the driver feels uncomfortable. Giving can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. This embodiment is a rear-wheel drive vehicle equipped with the lane departure prevention apparatus of 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 a first embodiment of a lane departure prevention apparatus according to the present invention.

  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.

  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 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 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.

  The vehicle is provided with a navigation device 15. The navigation device 15 detects the longitudinal acceleration Xg or lateral acceleration Yg generated in the host vehicle, or the yaw rate φ ′ generated in the host vehicle. The navigation device 15 outputs the detected longitudinal acceleration Xg, lateral acceleration Yg, 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.

  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 Acc. A steering angle sensor 19 for detecting the steering angle δ of the steering wheel 21, wheel speed sensors 22FL to 22RR for detecting the rotational speeds of the wheels 5FL to 5RR, so-called wheel speeds Vwi (i = fl, fr, rl, rr), A direction indicating switch 20 for detecting a direction indicating operation by the direction indicator is 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 Yg, and the yaw angle φ are positive values when turning left, and the lateral displacement X is a positive value when deviating from the center of the traveling lane to the left.
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 Xg, the lateral acceleration Yg, the yaw rate φ ′ and road information obtained by the navigation device 15, the wheel speeds Vwi, the steering angle δ, the accelerator opening Acc, the master cylinder hydraulic pressure detected by the sensors. Pmf, Pmr, direction switch signal, drive torque Tw from the drive torque control unit 12, and yaw angle φ, lateral displacement X, and travel lane curvature β are read from the imaging unit 15.

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. That is, for example, when ABS (Anti-lock Brake System) control or the like is operating, the estimated vehicle speed estimated in the ABS control is used as the vehicle speed V. Further, a value used for navigation information in the navigation device 15 may be used as the vehicle speed V.
Subsequently, in step S3, the traveling environment is determined. Specifically, the type of road on which the host vehicle is traveling and the traveling lane of the host vehicle are detected. And from the detection result, the direction based on the safety degree is determined. The determination is made based on road information, that is, the number of lanes, road type information indicating whether the road is a general road or a highway, and image information obtained by the imaging unit 13. FIG. 3 shows a specific processing procedure for determining the driving environment.

First, in step S21, the currently traveling road type (general road or highway) is acquired from the road information from the navigation device 15. Furthermore, in step S22, the number of lanes of the currently traveling road is acquired from the road information from the navigation device 15.
Subsequently, in step S23, a white line portion (lane marking line portion) is extracted from the captured image obtained by the imaging unit 13. Here, as shown in FIG. 4, a case where the host vehicle is traveling on a three-lane road on one side will be described as an example. As shown in FIG. 4, the road is divided into first to fourth white lines LI1, LI2, LI3, and LI4 from the left side, and is configured as a three-lane road on one side. When the host vehicle travels on such a road, the captured image obtained for each lane is different. Further, the image formed by extracting the white line from the image also differs depending on the traveling lane.

  That is, when the host vehicle 100A is traveling in the left lane in the traveling direction, the captured image P obtained by the imaging unit 13 of the host vehicle 100A is mainly the first as shown in FIG. , A unique image constituted by the second and third white lines LI1, LI2, and LI3. Further, when the host vehicle 100B is traveling in the central lane, the captured image P obtained by the imaging unit 13 of the host vehicle 100B is mainly the first, second, and second as shown in FIG. 3 and the fourth white line LI1, LI2, LI3, LI4. Further, when the host vehicle 100C is traveling in the right lane in the traveling direction, the captured image P obtained by the imaging unit 13 of the host vehicle 100C is mainly the second as shown in FIG. , A unique image constituted by the third and fourth white lines LI2, LI3, and LI4. Thus, the configuration of the white line in the image differs depending on the travel lane.

  Subsequently, in step S24, the host vehicle travel lane (host vehicle travel lane) is determined. Specifically, the host vehicle travel lane is determined based on the information obtained in steps S22 and S23. In other words, the host vehicle travel lane is determined based on the number of lanes of the road on which the host vehicle is currently traveling and the captured image (image obtained by extracting the white line) obtained by the imaging unit 13. For example, an image obtained in accordance with the number of lanes and the traveling lane is previously stored as image data, and the image data prepared in advance and the number of lanes on the road on which the host vehicle is currently traveling and the current obtained by the imaging unit 13 are stored. The captured vehicle image (image obtained by extracting the white line) is compared to determine the vehicle lane.

  Subsequently, in step S25, the degree of safety in the left-right direction viewed from the lane in which the host vehicle is traveling is determined. Specifically, the direction in which the degree of safety is low when the host vehicle deviates is held as information. Thus, when the safety level is low in the left direction when viewed from the lane in which the host vehicle is traveling, the direction is held as a low safety level direction (hereinafter referred to as a first obstacle existence direction) Sout ( Sout = left) When the safety level is low in the right direction when viewed from the lane in which the host vehicle is traveling, the direction is held as the first obstacle existence direction Sout (Sout = right). For example, the determination is made as follows.

  For example, in FIG. 4, when the host vehicle 100A is traveling in the left lane, the degree of safety is lower when the vehicle deviates to the left of the left lane than to deviate to the right of the left lane. This is because there is a road shoulder in the left direction of the left lane, and there is a high possibility that a wall, a guardrail, an obstacle, a cliff, or the like is on the road shoulder. Accordingly, when the host vehicle 100A is traveling in the left lane, it is determined that the first obstacle existence direction Sout is the left direction (Sout = left).

In addition, when the host vehicle 100B is traveling in the central lane, the vehicle 100B is still in the road no matter which direction it deviates, so the safety degree is the same in either the left or right direction with respect to the current traveling lane. become.
Further, when the host vehicle 100C is traveling in the right lane, the degree of safety is lower in the right direction, that is, when the vehicle deviates to the opposite lane than when the vehicle deviates to the left direction, that is, the adjacent lane. Therefore, in this case, when the host vehicle 100A is traveling in the right lane, it is determined that the first obstacle existence direction Sout is the right direction (Sout = right).

Moreover, when compared with ordinary roads and expressways, the width of shoulders on ordinary roads is narrower than that of expressways, there are many obstacles on the shoulders, and there are also pedestrians. For this reason, deviating to the shoulder side on a general road is less safe than deviating to the shoulder side on an expressway.
Further, when compared by the number of lanes, the safety degree is lower when the left side is the road shoulder and the right direction is one lane on the opposite lane. In this case, it is determined that the left and right directions are the first obstacle existence direction Sout (Sout = both).

  Note that, for example, since one-sided one-lane roads generally do not have a median strip or guardrail, a captured image when traveling on the one-sided one-lane road is as shown in FIG. . That is, the captured image when traveling on a one-lane road is the same as the captured image obtained by the imaging unit 13 of the vehicle 100A by traveling on the left lane of a three-lane road. Therefore, when it is assumed that the vehicle travels on a general road and an expressway, the presence direction of the first obstacle or the like cannot be determined only by the captured image. For this reason, the number of lanes of the road on which the host vehicle is currently traveling is obtained from the navigation device 15, and it is determined whether the currently traveling road is a one-lane or one-lane road. Thus, when driving on a one-lane road on one side, it can also be determined that the degree of safety is low in the right direction.

The travel environment is determined in step S3 shown in FIG. 2 according to the processing procedure shown in FIG.
Subsequently, in step S4, a lane departure tendency is determined. Specifically, the processing procedure of this determination processing is as shown in FIG.
First, in step S31, a predicted departure time Tout is calculated. Specifically, the deviation predicted time Tout is calculated by the following equation (2) using dx as the change amount of the lateral displacement X (change amount per unit time), L as the lane width, and the lateral displacement X. (See FIG. 7 for values of X, dx, and L).

Tout = (L / 2−X) / dx (2)
According to the equation (2), the vehicle 100 that is laterally displaced by X from the center of the lane (X = 0) reaches the outside position region (for example, the road shoulder) separated from the position by the distance L / 2. The predicted time Tout can be obtained.
Note that the lane width L is obtained by the imaging unit 13 processing the captured image. Further, the position of the vehicle may be obtained from the navigation device 15 or the lane width L may be obtained from the map data of the navigation device 15.

  Subsequently, in step S32, a departure determination flag is set. Specifically, the predicted departure time Tout is compared with a predetermined first departure determination threshold value Ts. Here, if the predicted departure time Tout is less than the first departure determination threshold value Ts (Tout <Ts), it is determined that the departure (there is a departure tendency) and the departure determination flag Fout is turned on (Fout = ON). . If the predicted departure time Tout is equal to or greater than the first departure determination threshold value Ts (Tout ≧ Ts), it is determined that there is no departure (no departure tendency) and the departure determination flag Fout is turned off (Fout = OFF).

  By the process of step S32, for example, when the host vehicle moves away from the center of the lane and the predicted departure time Tout becomes less than the first departure determination threshold value Ts (Tout <Ts), the departure determination flag Fout is turned on. (Fout = ON). Further, when the own vehicle (the own vehicle in the state where Fout = ON) returns to the lane center side and the estimated departure time Tout becomes equal to or longer than the first departure determination threshold value Ts (Tout ≧ Ts), the departure determination. The flag Fout is turned off (Fout = OFF). For example, when there is a tendency to deviate, if the braking control for avoiding deviation described later is performed, or if the driver himself performs an avoidance operation, the deviation determination flag Fout is changed from ON to OFF.

The first departure determination threshold value Ts can be changed. That is, for example, the first departure determination threshold value Ts can be set based on the safety degree obtained in step S3.
Subsequently, in step S33, 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 a determination result that there is no deviation.

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 deviates 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, if the steering angle δ and the change amount of the steering angle (change amount per unit time) Δδ are equal to or larger than the set value, the driver consciously changes the lane. The departure determination flag Fout is changed to OFF (Fout = OFF).

Subsequently, in step S6, a control method for avoiding deviation is determined. Specifically, whether or not to perform a departure warning or braking control for avoiding departure, and further, when performing braking control for avoiding departure, the braking control method is determined.
For example, a departure warning is activated according to the ON / OFF state of the departure determination flag Fout obtained in step S5. For example, when the departure determination flag Fout is ON (Tout <Ts), but it can be determined that the lane does not deviate due to a steering operation by the driver, a departure warning is performed. For example, an alarm is given by sound or display.

Here, the departure determination flag Fout is ON (Tout <Ts), but the case where it can be determined that the lane does not deviate due to the steering operation by the driver, for example, the driver himself notices the departure tendency of the own vehicle. In this case, the departure determination flag Fout itself is still ON (Tout <Ts).
Further, when the departure determination flag Fout is ON (Tout <Ts), a braking control method for avoiding departure based on the first obstacle existence direction Sout obtained in step S3 and the departure direction Dout obtained in step S4 is also provided. decide. This will be described in detail later.

Subsequently, in step S7, a target yaw moment to be generated in the host vehicle is calculated. This target yaw moment is a yaw moment to be given to the host vehicle in order to avoid departure.
Specifically, the target yaw moment Ms is calculated by the following equation (3) based on the lateral displacement X and the change dx obtained in step S1.
Ms = K1 · X + K2 · dx (3)
Here, K1 and K2 are gains that vary according to the vehicle speed V. For example, FIG. 8 shows an example. As shown in FIG. 8, for example, the gains K1 and K2 are small values in the low speed range. When the vehicle speed V reaches a certain value, the gains K1 and K2 increase in response to the increase in the vehicle speed V, and then constant when the vehicle speed V reaches a certain value. Value.

Subsequently, in step S8, a deceleration for avoiding deviation 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 (4).
Pgf = Kgv · V + Kgx · dx (4)
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. For example, FIG. 9 shows an example. As shown in FIG. 9, 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.

Then, based on the target braking hydraulic pressure Pgf for the front wheels, the target braking hydraulic pressure Pgr for the rear wheels considering the front-rear distribution is calculated.
Thus, in step S8, deceleration for avoiding deviation (specifically, target braking hydraulic pressures Pgf, Pgr) is obtained.
Subsequently, in step S9, it is determined whether or not the departure determination flag Fout is ON. If the departure determination flag Fout is ON, the process proceeds to step S10. If the departure determination flag Fout is OFF, the process proceeds to step S12.

In step S10, the steering angle direction is determined. Specifically, it is determined whether or not the rudder angle direction and the departure avoidance direction match. Here, the departure avoidance direction is a direction for avoiding the departure in the departure direction obtained in step S4, that is, the counter departure direction. The steering angle direction is obtained based on the steering angle δ obtained in step S1.
If the rudder angle direction and the departure avoidance direction match, the process proceeds to step S12. If the rudder angle direction and the departure avoidance direction do not coincide, the process proceeds to step S11.

In step S11 and step S12, the target brake hydraulic pressure of each wheel is calculated.
First, in step S12, the target brake hydraulic pressure is calculated as follows when the departure determination flag Fout is OFF (Fout = OFF), that is, when the determination result that there is no departure is obtained.
As shown in the following equations (5) and (6), the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is set to the master cylinder hydraulic pressures Pmf, Pmr.
Psfl = Psfr = Pmf (5)
Psrl = Psrr = Pmr (6)
Here, Pmf is the master cylinder hydraulic pressure for the front wheels. Pmr is a master cylinder hydraulic pressure for the rear wheels, and is a value calculated based on the master cylinder hydraulic pressure Pmf for the front wheels in consideration of the front-rear distribution.

On the other hand, in step S11, when the departure determination flag Fout is ON (Fout = ON), that is, when a determination result indicating departure is obtained, the target braking hydraulic pressure is calculated as follows.
First, based on the target yaw moment Ms, a front wheel target braking hydraulic pressure difference ΔPsf and a rear wheel target braking hydraulic pressure difference ΔPsr are calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (7) to (10).
In the case of Ms <Ms1, ΔPsf = 0 (7)
ΔPsr = 2 · Kbr · Ms / T (8)
When Ms ≧ Ms1 ΔPsf = 2 · Kbf · (Ms−Ms1) / T (9)
ΔPsr = 2 · Kbr · Ms1 / T (10)
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. That is, 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.

  When the departure determination flag Fout is ON (Fout = ON), the final wheels are calculated using the target braking fluid pressure differences ΔPsf and ΔPsr and the deceleration target braking fluid pressures Pgf and Pgr calculated as described above. Target brake hydraulic pressure Psi (i = fl, fr, rl, rr) is calculated. Specifically, the final target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated based on the braking control method determined in step S6.

Here, the braking control method determined in step S6 will be described.
In step S6, the braking control to be activated when the departure determination flag Fout is ON is determined based on the first obstacle existence direction Sout and the departure direction Dout. Here, the first obstacle existence direction is determined. The braking control method will be described for each of the cases of Sout and departure direction Dout (first case to third case).

(First Case) When the first obstacle existence direction Sout and the departure direction Dout do not coincide with each other, a yaw moment for avoiding departure is applied to the vehicle until the departure determination flag Fout is turned off. Thus, braking control (hereinafter referred to as deviation avoidance yaw control) is performed.
Here, the magnitude of the yaw moment applied to the vehicle in order to avoid the departure is the target yaw moment Ms. The yaw moment is applied to the vehicle by making a difference in the braking force applied to the left and right wheels. Specifically, as described above, when the target yaw moment Ms is less than the setting threshold value Ms1, a braking force difference is generated between the left and right rear wheels to apply the target yaw moment Ms to the vehicle. When the target yaw moment Ms is equal to or greater than the setting threshold value Ms1, a braking force difference is generated between the front, rear, left and right wheels, and the target yaw moment Ms is applied to the vehicle.
Further, the case where the departure determination flag Fout is changed from ON to OFF is when braking control for avoiding departure is performed or the driver himself performs an avoidance operation when there is a departure tendency.

(Second Case) When the first obstacle existence direction Sout matches the departure direction Dout and the road type R obtained in Step S3 is a general road, the departure is continued until the departure determination flag Fout is turned OFF. Perform avoidance yaw control.
Further, a second departure judgment threshold value Tr (Ts>Tr> 0) less than the first departure judgment threshold value Ts is defined, and the predicted departure time Tout is smaller than the second departure judgment threshold value Tr. When this happens, in addition to the departure avoidance yaw control, braking control for decelerating the vehicle (hereinafter referred to as departure avoidance deceleration control) is performed. This departure avoidance deceleration control is performed by applying the same level of braking force to the left and right wheels.

(Third Case) When the first obstacle existence direction Sout and the departure direction Dout coincide with each other and the road type R obtained in step S3 is a highway, the departure is continued until the departure determination flag Fout is turned off. Perform avoidance yaw control.
Further, in this case, when the predicted departure time Tout becomes 0, the departure avoidance deceleration control is performed in addition to the departure avoidance yaw control.
In the case of the third case, as in the case of the second case, the braking control for decelerating the vehicle also when the predicted departure time Tout becomes smaller than the second departure determination threshold value Tr. (Deceleration avoidance deceleration control) may be performed. In this case, for example, when the estimated departure time Tout becomes 0, the deceleration of the host vehicle by the departure avoidance deceleration control is further increased. Thereby, when the predicted departure time Tout becomes smaller than the second departure determination threshold value Tr, and further when the predicted departure time Tout becomes 0, the departure avoidance deceleration control is activated. In this case, when the estimated departure time Tout becomes 0, the deceleration of the host vehicle becomes larger.

  In step S6, various braking control methods are determined according to the state of the first obstacle etc. existence direction Sout and the departure direction Dout. In other words, depending on the state of the first obstacle etc. existence direction Sout and the departure direction Dout, only the departure avoidance yaw control, or the combination of the departure avoidance yaw control and the departure avoidance deceleration control, The braking control method is determined.

In step S11, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated corresponding to such various braking control methods.
For example, in the deviation avoidance yaw control in the first to third cases, the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (11). .
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
(11)

In the case of the second and third cases, deviation avoidance yaw control and departure avoidance deceleration control are performed. In this case, the target braking hydraulic pressure Psi of each wheel is expressed by the following equation (12). (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
(12)
Further, as shown by the equations (11) and (12), the deceleration operation by the driver, that is, the target brake fluid pressure Psi (i = fl, fr, rl, rr) is calculated.

  The above is the process of step S11. In step S11 or step S12, the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated based on the state of the departure determination flag Fout. When the departure determination flag Fout is ON (step S12), it corresponds to various braking control methods determined in accordance with the state of the first obstacle etc. existence direction Sout and the departure direction Dout in step S6. The target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated.

The above is the calculation processing by the braking / driving force control unit 8. Then, the braking / driving force control unit 8 uses the target braking fluid pressure Psi (i = fl, fr, rl, rr) calculated in step S11 or step S12 as a braking fluid pressure command value to control the braking fluid pressure. Output to unit 7.
The lane departure prevention apparatus as described above generally operates as follows.
First, various data are read from each sensor, controller, and control unit (step S1). Subsequently, the vehicle speed V is calculated (step S2).
Subsequently, the traveling environment is determined, and the direction in which the degree of safety is low (the first obstacle etc. existence direction Sout) is determined (step S3, FIG. 3). For example, when the host vehicle 100A is traveling in the left lane in FIG. 4, the first obstacle existence direction Sout is set to the left.

Further, the departure determination flag Fout is set based on the estimated departure time Tout, and the departure direction Dout is determined based on the lateral displacement X (step S4, FIG. 7).
Further, the driver's intention to change the lane is determined based on the departure direction Dout thus obtained and the direction indicated by the direction switch signal (the blinker lighting side) (step S5).
For example, when the direction indicated by the direction switch signal (the blinker lighting side) and the direction indicated by the departure direction Dout are the same, it is determined that the driver has intentionally changed the lane. In this case, the departure determination flag Fout is changed to OFF.

  In addition, when the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout, the departure determination flag Fout is maintained when it is ON. For example, if the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout, the departure behavior of the vehicle is not the vehicle behavior due to the driver's intention such as a lane change by the driver. Since it can be considered, if the departure determination flag Fout is ON, it is maintained.

Based on the departure determination flag Fout, the first obstacle existence direction Sout, and the departure direction Dout, the presence or absence of an alarm for avoiding departure, the presence or absence of braking control for avoiding departure, and the braking control for avoiding departure Is determined (step S6).
Further, the target yaw moment Ms is calculated based on the lateral displacement X and the change amount dx (step S7), and the deceleration for avoiding deviation is calculated (step S8).
Based on the departure determination flag Fout, the steering angle direction, and the departure avoidance direction, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated (steps S9 to S12).

  Specifically, when the departure determination flag Fout is OFF, or when the departure determination flag Fout is ON, the steering angle direction and the departure avoidance direction coincide with each other, the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) are set to the master cylinder hydraulic pressures Pmf, Pmr (steps S9, S10, S12). Further, when the departure determination flag Fout is ON and the steering angle direction and the departure avoidance direction do not coincide with each other, the braking control method determined based on the first obstacle existence direction Sout and the departure direction Dout in step S6 is realized. The target braking fluid pressure Psi (i = fl, fr, rl, rr) for each wheel is calculated (steps S9 to S11).

The target brake fluid pressure Psi (i = fl, fr, rl, rr) calculated according to each condition is output to the brake fluid pressure controller 7 as a brake fluid pressure command value. 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. As a result, when the vehicle tends to deviate, a predetermined vehicle behavior is exhibited according to the traveling environment.
Here, in the case of the first case to the third case, the vehicle behavior when the braking control is performed will be described with reference to FIGS. 10 and 11.

  As described above, the second case is a case where the first obstacle existence direction Sout matches the departure direction Dout and the road type R is a general road. That is, as shown in FIG. 10, when the host vehicle 100 is traveling in one lane on one side such that the left side is the road shoulder A and the right side is the opposite lane (center lane LI5 side), the host vehicle 100 ( This is a case where the host vehicle 100 at the top position in FIG. 10 tends to deviate leftward or the host vehicle (the host vehicle 100 at an intermediate position in FIG. 10) tends to deviate rightward.

  In this case, deviation avoidance yaw control is performed. Further, when the predicted departure time Tout becomes shorter than the second departure determination threshold Tr, departure avoidance deceleration control is performed in addition to departure avoidance yaw control. Thereby, the own vehicle avoids deviation. On the other hand, the driver can feel the departure avoidance operation of the vehicle as the acceleration in the lateral direction or the deceleration in the traveling direction, and can know that the own vehicle tends to depart.

  Further, as described above, the third case is a case where the first obstacle existence direction Sout matches the departure direction Dout and the road type R is a highway. That is, as shown in FIG. 11, in the three-lane road, the host vehicle 100A traveling in the left lane (the host vehicle 100A in the uppermost position in FIG. 11) tends to deviate in the left direction. Alternatively, as shown in FIG. 11, in the three-lane road, the host vehicle 100C traveling in the right lane (the host vehicle 100C at the intermediate position in FIG. 11) tends to deviate in the right direction.

In this case, deviation avoidance yaw control is performed. Thereby, the own vehicle can avoid deviation. Further, when the predicted departure time Tout becomes 0, that is, when it is determined that the host vehicle has deviated from the traveling lane, the departure avoidance deceleration control is performed in addition to the departure avoidance yaw control.
In FIG. 10 and FIG. 11, the black wheels indicate wheels that generate hydraulic pressure and are given braking force. That is, when either one of the left and right wheels is a black wheel, there is a difference in hydraulic pressure or braking force between the left and right wheels. In this case, a yaw moment is given to the vehicle. Even if the left and right wheels are black wheels, there may be a difference in the hydraulic pressure values. In this case, it is confirmed that the vehicle is being subjected to deceleration control while a yaw moment is applied to the vehicle. Show. This relationship is the same in subsequent drawings.

  Further, as described above, the first case is a case where the first obstacle existence direction Sout and the departure direction Dout do not match. That is, as shown in FIG. 11, in a three-lane road, the host vehicle 100A traveling in the left lane (host vehicle 100A in the middle position in FIG. 11) tends to deviate in the right direction. Alternatively, as shown in FIG. 11, in a three-lane road, the host vehicle 100C traveling in the right lane (the host vehicle 100C in the uppermost position in FIG. 11) tends to deviate in the left direction. Alternatively, the host vehicle B traveling in the central lane tends to deviate leftward or rightward. In this case, deviation avoidance yaw control is performed. Thereby, the own vehicle can avoid deviation.

In addition to such braking control for avoiding deviation, a warning is given by sound and display. For example, the alarm is started at a predetermined timing simultaneously with the start of the brake control or prior to the brake control.
Here, the control for departure avoidance performed in the above first to third cases is based on the condition that the departure determination flag Fout is ON and the steering angle direction and the departure avoidance direction do not match. On the other hand, when the departure determination flag Fout is OFF, or when the departure determination flag Fout is ON, the steering angle direction and the departure avoidance direction coincide with each other. Absent.

Next, the effect will be described.
As described above, when the steering angle direction by the driver's steering operation and the departure avoidance direction (the reverse direction of the departure direction Dout) coincide with each other, the control for avoiding departure is suppressed, and not specifically performed. I have to. In this case, a yaw moment is applied to the vehicle so that the steering angle direction is determined by the driver's steering operation. Accordingly, it is possible to prevent the yaw moment for avoiding the deviation from being added to the yaw moment to the vehicle by the steering operation of the driver, and the yaw moment from acting on the vehicle more than necessary. As a result, it is possible to prevent the control for avoiding the departure from giving the driver an uncomfortable feeling.

Next, a second embodiment will be described. This second embodiment is also a vehicle provided with a vehicle departure prevention device. The configuration of the vehicle according to the second embodiment is the same as the configuration of the vehicle according to the first embodiment (see FIG. 1).
In the first embodiment, when the rudder angle direction and the departure avoidance direction coincide with each other, control for departure avoidance is not performed. On the other hand, in the second embodiment, even when the steering angle direction and the departure avoidance direction coincide with each other, control for departure avoidance is made to intervene. Specifically, control for avoiding deviation is made to intervene in consideration of the magnitude of the yaw moment generated by steering. In order to realize this, in the second embodiment, the processing contents of the braking / driving force control unit 8 are different from those in the first embodiment.

Note that other configurations of the vehicle of the second embodiment are the same as those of the first embodiment unless otherwise specified.
The calculation processing procedure performed by the braking / driving force control unit 8 is as shown in FIG. The calculation processing procedure is almost the same as the calculation processing procedure of the first embodiment, and particularly different parts will be described.
That is, in step S1 to step S9, similar to the first embodiment, various data are read, vehicle speed is calculated, driving environment is determined, lane departure tendency is determined, driver's intention is determined, and control method is determined. Determination, calculation of target yaw moment, and calculation of deceleration for avoiding deviation. In step S9, it is determined whether the departure determination flag Fout is ON. If the departure determination flag Fout is ON, the process proceeds to step S41. If the departure determination flag Fout is OFF, the process proceeds to step S12.

  In step S41, the steering angle direction is determined as in step S10. That is, it is determined whether or not the rudder angle direction and the departure avoidance direction coincide with each other. If the rudder angle direction and the departure avoidance direction do not coincide with each other, the process proceeds to step S11, and the rudder angle direction and the departure avoidance direction are determined. If they match, the process proceeds to step S42. Here, in the second embodiment, when the rudder angle direction and the departure avoidance direction match in step S41, the process proceeds to step S42 instead of proceeding to step S12.

In step S42, a yaw moment (hereinafter referred to as a steering yaw moment) Mh generated in the vehicle according to the steering angle δ is calculated as an estimated value.
In step S43, the steering yaw moment Mh calculated in step S42 is compared with the target yaw moment Ms calculated in step S7. If the steering yaw moment Mh is greater than or equal to the target yaw moment Ms, the process proceeds to step S12. If the steering yaw moment Mh is less than the target yaw moment Ms, the process proceeds to step S44.

In step S44, a final target yaw moment Ms ′ is calculated. Specifically, the difference (Ms−Mh) between the target yaw moment Ms and the steering yaw moment Mh is calculated as the final target yaw moment Ms ′.
Subsequently, in step S11, the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is set so that the yaw moment applied to the vehicle by the deviation avoidance yaw control becomes the final target yaw moment Ms ′. Is calculated (see the equations (11) and (12)).

If the rudder angle direction does not coincide with the departure avoidance direction in step S41, the yaw moment applied to the vehicle by the departure avoidance yaw control is set to the target yaw moment Ms in step S11. Then, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated (see the above formulas (11) and (12)).
In step S12, the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is set to the master cylinder hydraulic pressure Pmf, Pmr (see the formulas (5) and (6)).

  Thus, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated according to each condition, and the calculated target braking fluid pressure Psi (i = fl, fr, rl, rr) is used as the braking fluid. The pressure command value is output to the brake fluid pressure control unit 7. 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. As a result, when the vehicle tends to deviate, a predetermined vehicle behavior is exhibited according to the traveling environment.

  With the above processing, when the departure determination flag Fout is ON, the steering angle direction matches the departure avoidance direction (the reverse direction of the departure direction Dout) and the steering yaw moment Mh is less than the target yaw moment Ms. The final target yaw moment Ms ′ is calculated from the difference (Ms−Mh) between the target yaw moment Ms and the steering yaw moment Mh (steps S41 to S44), so that the final target yaw moment Ms ′ is obtained. Deviation avoidance yaw control is performed (step S11). As a result, the yaw moment based on the driver's steering operation and the final target yaw moment Ms ′ for avoiding departure are simultaneously applied to the vehicle.

Further, when the departure determination flag Fout is ON, when the steering angle direction does not coincide with the departure avoidance direction, the departure avoidance yaw control is performed so that the target yaw moment Ms is obtained, as in the first embodiment. Perform (step S41, step S11).
Even when the departure determination flag Fout is ON, the departure avoidance yaw control is not performed when the steering yaw moment Mh is equal to or greater than the target yaw moment Ms. In this case, only the yaw moment based on the driver's steering operation is applied to the vehicle (steps S43 and S12).

Next, the effect of the second embodiment will be described.
As described above, when the departure determination flag Fout is ON, the steering angle direction and the departure avoidance direction (the reverse direction of the departure direction Dout) match and the steering yaw moment Mh is less than the target yaw moment Ms. The final target yaw moment Ms ′ is calculated from the difference (Ms−Mh) between the target yaw moment Ms and the steering yaw moment Mh (steps S41 to S44), and departure is avoided so as to be the final target yaw moment Ms ′. Yaw control is performed (step S11). Thus, the yaw moment based on the driver's steering operation and the final target yaw moment Ms ′ for avoiding the departure are simultaneously applied to the vehicle.

By doing so, it is possible to prevent the yaw moment from acting on the host vehicle more than necessary when the driver is steering, as in the first embodiment.
Further, the sum of the yaw moment based on the steering operation of the driver and the final target yaw moment Ms ′ for avoiding the departure becomes the target yaw moment Ms. That is, the yaw moment that can avoid the deviation under the optimum conditions is obtained. This allows the vehicle to operate optimally and avoid deviations. In other words, the deviation avoidance yaw control is intervened so as to supplement the driver's steering operation, and the optimum operation can be performed to avoid the deviation. As a result, the deviation avoidance yaw control intervenes, but the intervention does not give the driver an uncomfortable feeling.

Here, the effect will be described with reference to FIG. Here, in FIGS. 13A to 13C, the left diagram shows the traveling state of the host vehicle 100, and the right diagram shows the steering state of the steering wheel 21 by the driver of the host vehicle 100. .
Although described with reference to FIGS. 10 and 11, as shown in FIG. 13A, in principle, when there is a tendency to deviate, the deviation avoidance yaw control operates to avoid the deviation. .

  On the other hand, when there is a tendency to deviate, it is common for the driver to operate the steering wheel to take an action of avoiding deviation. Therefore, if the deviation avoidance yaw control is performed without any limitation when there is a tendency to deviate, the yaw moment Ms by the deviation avoidance control and the operation of the steering wheel 21 by the driver are shown as shown in FIG. The yaw moment Mh due to the above acts on the vehicle 100. In this case, an excessive yaw moment is applied to the vehicle 100 rather than a yaw moment sufficient to avoid departure.

  Therefore, in the present invention, when the rudder angle direction coincides with the departure avoidance direction and the yaw moment Mh by the steering operation is less than the target yaw moment Ms, the final target yaw moment Ms ′ obtained by subtracting the target yaw moment Ms. Is set as a target value, and deviation avoidance yaw control is performed so as to be the target value (see (C) in FIG. 13). This allows the vehicle to operate optimally and avoid deviations.

Next, a third embodiment will be described. This third embodiment is also a vehicle including a vehicle departure prevention device. The configuration of the vehicle according to the third embodiment is the same as the configuration of the vehicle according to the first embodiment (see FIG. 1).
In the third embodiment, it is determined whether or not to intervene control for deviation avoidance based on the steering angular speed when the steering operation is performed by the steering wheel. In order to realize this, in the third embodiment, the processing contents of the braking / driving force control unit 8 are different from those in the first and second embodiments.

Note that the other configurations of the vehicle of the third embodiment are the same as the configurations of the first embodiment unless otherwise specified.
The calculation processing procedure performed by the braking / driving force control unit 8 is as shown in FIG. The calculation processing procedure is almost the same as the calculation processing procedure of the first embodiment, and particularly different parts will be described.

  That is, in step S1 to step S9, similar to the first embodiment, various data are read, vehicle speed is calculated, driving environment is determined, lane departure tendency is determined, driver's intention is determined, and control method is determined. Determination, calculation of target yaw moment, and calculation of deceleration for avoiding deviation. In step S9, it is determined whether the departure determination flag Fout is ON. If the departure determination flag Fout is ON, the process proceeds to step S51. If the departure determination flag Fout is OFF, the process proceeds to step S12.

In step S51, the steering angular velocity δ ′ is compared with a predetermined threshold value δc ′. Here, the steering angular velocity δ ′ is obtained as a time differential value of the steering angle δ. When the steering angular velocity δ ′ is greater than the predetermined threshold value δc ′, the process proceeds to step S12. When the steering angular speed δ ′ is equal to or less than the predetermined threshold value δc ′, the process proceeds to step S11.
In step S11, the target braking hydraulic pressure Psi (i = fl, fr, rl, i) of each wheel for realizing the braking control method determined based on the first obstacle existence direction Sout and the departure direction Dout in step S6. rr) is calculated. On the other hand, in step S12, the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is set to the master cylinder hydraulic pressures Pmf, Pmr. The target brake fluid pressure Psi (i = fl, fr, rl, rr) calculated according to each condition is output to the brake fluid pressure controller 7 as a brake fluid pressure command value. 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.

  By the above processing, when the deviation determination flag Fout is ON, when the steering angular speed δ ′ is larger than the predetermined threshold value δc ′, the control for avoiding the deviation is not performed (Step S51, Step S12). On the other hand, when the deviation determination flag Fout is ON, when the steering angular velocity δ ′ is equal to or less than the predetermined threshold value δc ′, the control for avoiding the deviation is activated (steps S51 and S11).

Next, the effect of the third embodiment will be described.
As described above, when the rudder angular velocity δ ′ is larger than the predetermined threshold value δc ′, control for avoiding deviation is not performed (steps S51 and S12). Here, the control for departure avoidance is the yaw control for departure avoidance and the deceleration control for departure avoidance.
Thus, as in the first embodiment, when the driver is performing a predetermined steering operation, the departure avoidance yaw control and departure avoidance deceleration control are not activated more than necessary. I am doing so. As a result, it is possible to prevent the control for avoiding the departure from giving the driver an uncomfortable feeling.

  For example, when there is an obstacle on the road, the driver quickly turns the steering wheel to prevent the vehicle from coming into contact with the obstacle. In such a scene, the operation speed δ ′ increases. On the other hand, in such a situation, the vehicle departure prevention device usually detects that there is a tendency to deviate. At this time, control for departure avoidance such as yaw control for departure avoidance and deceleration control for departure avoidance is activated.

  For this reason, when the rudder angular velocity δ ′ is equal to or higher than a predetermined threshold value δc ′, an attempt is made to avoid an obstacle on the road by preventing intervention of such deviation avoidance control. The vehicle operation by the driver can be completed smoothly. In this case, the vehicle operation by the driver can be performed smoothly by not intervening the deceleration control for avoiding deviation. In other words, since the vehicle behavior by the driver and the vehicle behavior by the control do not interfere with each other, the driver can operate the vehicle with a normal feeling. Further, the same effect can be obtained by not interposing the deviation avoidance yaw control.

The embodiment of the present invention has been described above. However, the present invention is not limited to being realized as the above-described embodiment.
That is, in the above-described embodiment, the braking control (deviation avoidance yaw control) is performed so that the yaw moment for avoiding the departure is applied to the vehicle, and the braking control (departure avoidance) for decelerating to avoid the departure. The method of combination with the speed reduction control), the operation sequence thereof, and the control amount (the magnitude of the yaw moment and the magnitude of the deceleration) have been specifically described. However, it goes without saying that the present invention is not limited to this.

  For example, in the above-described embodiment, as a specific example of setting the yaw moment to be performed based on the steering state to a small value and the degree of deceleration to a small value, departure avoidance yaw control or departure avoidance deceleration control Is supposed not to operate. However, it is not limited to this. That is, for example, the control amounts (the magnitude of the yaw moment and the magnitude of the deceleration) of the departure avoidance yaw control and the departure avoidance deceleration control may be changed to small values based on the steering state. By doing so, departure avoidance yaw control and departure avoidance deceleration control can be suppressed.

Further, in the above-described embodiment, the estimated departure time Tout is calculated based on the lateral displacement X and the amount of change dx (see equation (2) above). However, the deviation prediction time Tout may be obtained by other methods. For example, the predicted departure time Tout may be obtained based on the yaw angle φ, the travel lane curvature β, the yaw rate φ ′, or the steering angle δ.
In the above-described embodiment, the driver's intention to change the lane is obtained based on the steering angle δ and the change amount Δδ of the steering angle (see step S5). However, the driver's intention to change lanes may be obtained by other methods. For example, the driver's intention to change the lane may be obtained based on the steering torque.

In the above-described embodiment, the target yaw moment Ms is calculated based on the lateral displacement X and the change amount dx (see the above formula (3)). However, the target yaw moment Ms may be obtained by other methods. For example, as shown in the following equation (13), the target yaw moment Ms may be calculated based on the yaw angle φ, the lateral displacement X, and the travel lane curvature β.
Ms = K3 · φ + K4 · X + K5 · β (13)
Here, K3, K4, and K5 are gains that vary according to the vehicle speed V.

In the above-described embodiment, the target braking hydraulic pressure Pgf for the front wheels is described using a specific equation (see the equation (4)). However, it is not limited to this. For example, the target braking hydraulic pressure Pgf for the front wheels may be calculated by the following equation (14).
Pgf = Kgv · V + Kgφ · φ + Kgβ · β (14)
Here, Kgφ and Kgβ are conversion coefficients for converting braking force into braking hydraulic pressure, which are set based on the yaw angle φ and the travel lane curvature β, respectively.

Further, in the above-described embodiment, the target braking hydraulic pressure differences ΔPsf and ΔPsr between the front wheels and the rear wheels are calculated in order to realize the deviation avoidance yaw control (see the equations (7) and (8)). . However, it is not limited to this. For example, the deviation avoidance yaw control may be realized only by the target brake hydraulic pressure difference ΔPsf of the front wheels. In this case, the target braking hydraulic pressure difference ΔPsf of the front wheels is calculated by the following equation (15).
ΔPsf = 2 · Kbf · Ms / T (15)

  In the above description of the embodiment, the processing in the steering angle sensor 19 and the braking force control unit 8 (the step S1) realizes a steering state detecting means for detecting the steering state, and the braking force control unit. The process of step S4 in FIG. 8 realizes a departure tendency detection means for detecting the departure tendency of the host vehicle from the traveling lane, and the process of step S6 of the braking force control unit 8 is performed by the departure tendency detection means. Based on the detected deviation tendency, setting means for setting the yaw moment sharing amount and the deceleration sharing amount is realized, and the processing of step S7 of the braking force control unit 8 is performed by the yaw moment set by the setting means. Calculate the target yaw moment to avoid deviation of the vehicle from the driving lane based on the share A target yaw moment calculating means is realized, and the processing of step S8 of the braking force control unit 8 realizes a deceleration control amount calculating means for calculating a deceleration control amount based on the deceleration sharing amount set by the setting means. The processing of the step S11 of the braking force control unit 8 includes the target yaw moment calculated by the target yaw moment calculating means and the deceleration control amount when the departure tendency detecting means detects the departure tendency. A braking force control means for controlling the braking force of each wheel based on the deceleration control amount calculated by the calculating means is realized.

The steps S10 shown in FIG. 2, the steps S41 to S44 shown in FIG. 12, and the step S51 shown in FIG. 14 are performed by the braking force control unit 8 in the steering state detected by the steering state detecting means. Based on this, the changing means for changing the control content of the braking force control means is realized.
Further, step S42 shown in FIG. 12 by the braking force control unit 8 realizes a steering yaw moment calculating means for calculating the yaw moment generated in the host vehicle by the steering.

1 is a schematic configuration diagram showing a first embodiment of a vehicle equipped with a lane departure prevention apparatus of the present 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 driving environment determination of the said braking / driving force control unit. It is a figure which shows the vehicle which is drive | working the one side 3 lane road. It is a figure which shows the picked-up image which a vehicle obtains in each lane position, when a vehicle drive | works the said one side 3 lane road. 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 deviation prediction time Tout. It is a characteristic view which shows the characteristic of the gains K1 and K2 used for calculation of the target yaw moment Ms. It is a characteristic view which shows the characteristic of the conversion factors Kgv and Kgx used for calculation of the target brake hydraulic pressure Pgf. It is the figure used for description of the braking control method in the case of the 2nd case. It is the figure used for description of the braking control method in the case of the 3rd case. FIG. 10 is a flowchart for explaining a second embodiment of the present invention and showing a processing content of a braking / driving force control unit when there is a following vehicle. It is the figure used for description of the effect of the 2nd Embodiment of this invention. It is a flowchart which shows the 3rd Embodiment of this invention and shows the processing content of the braking / driving force control unit when the following vehicle exists.

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 15 Navigation device 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 22FL to 22RR Wheel speed sensor

Claims (4)

A steering state detecting means for detecting a steering rudder status,
A departure tendency detecting means for detecting a departure tendency of the host vehicle from the traveling lane;
Setting means for setting a yaw moment share amount and a deceleration share amount based on the departure tendency detected by the departure tendency detection means;
Target yaw moment calculating means for calculating a target yaw moment for avoiding deviation from the traveling lane of the host vehicle based on the yaw moment sharing amount set by the setting means;
A deceleration control amount calculating means for calculating a deceleration control amount based on the deceleration sharing amount set by the setting means;
When the departure tendency detection means detects the departure tendency, the control of each wheel is controlled based on the target yaw moment calculated by the target yaw moment calculation means and the deceleration control amount calculated by the deceleration control amount calculation means. Braking force control means for controlling power;
Changing means for changing the control content of the braking force control means based on the steering state detected by the steering state detection means ,
Based on the target yaw moment, the braking force control means adjusts the braking force of the left and right wheels so that a yaw moment in a direction that avoids lane departure is applied to the host vehicle to generate a braking force difference between the left and right wheels. And, based on the deceleration control amount, adjust the braking force of the left and right wheels so that the host vehicle decelerates, and control the braking force of each wheel to generate equal braking force on the left and right wheels,
When the steering speed as the steering state is greater than a predetermined threshold, the changing means changes the control content of the braking force control means, and the deceleration control amount calculated by the deceleration control amount calculating means car beam deviation preventing system you and decreases the. When the steering direction as the steering state is a direction that avoids the deviation of the host vehicle from the traveling lane , the changing means changes the control content of the braking force control means to reduce the yaw moment to a small value. The lane departure prevention apparatus according to claim 1, wherein the lane departure prevention apparatus is changed. A steering yaw moment calculating means for calculating a yaw moment generated in the host vehicle by the steering;
The changing means, Misao steering direction as the steering state, if the direction of avoiding departure of the host vehicle from the driving lane, as altering the control content of the braking force control unit, the braking force of the left and right wheels The yaw moment to be applied to the host vehicle is changed to adjust the yaw moment calculated by the steering yaw moment calculating means and the yaw moment to be applied to the host vehicle by adjusting the braking force of the left and right wheels. lane departure prevention apparatus according to claim 1 or 2, characterized by a predetermined value. When the steering speed as the steering state is larger than a predetermined threshold value , the changing means changes the control content of the braking force control means to change the yaw moment to a small value. The lane departure prevention device according to any one of claims 1 to 3 .

Images