JP4367101B2 - 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 that informs the driver that the vehicle may deviate from the traveling lane by applying the yaw moment (see, for example, Patent Document 1).
JP 2000-33860 A

For example, in Patent Document 1, a lateral deviation state of the traveling position of the vehicle from the reference position of the traveling lane is detected by the lateral deviation state detecting means, and braking force is applied to the wheels based on the detected lateral deviation state. Thus, a yaw moment is applied to the vehicle to avoid the vehicle from deviating from the traveling lane. In other words, the technique disclosed in Patent Document 1 merely avoids the deviation of the host vehicle in consideration of only the positional relationship between the traveling lane and the host vehicle. Therefore, it is difficult to say that the control for avoiding lane departure is optimally performed.
Accordingly, the present invention has been made in view of the above-described problems, and an object thereof is to provide a lane departure prevention device that can optimally perform control for avoiding lane departure.

In order to solve the above-described problem, the lane departure prevention apparatus according to the present invention is applied to the own vehicle when the acceleration / deceleration of the own vehicle is a deceleration and an obstacle around the own vehicle is detected. The target yaw moment, which is the target value of the yaw moment to be applied, is changed to a smaller value than when the acceleration / deceleration of the host vehicle is not decelerated.

According to the present invention, when there is a tendency to deviate while the host vehicle is decelerating, it is possible to prevent the driver from feeling uncomfortable or troublesome by reducing the target yaw moment.

The best mode for carrying out 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 (Charge Coupled Device) camera. This imaging part 13 is installed in the front part of the vehicle.

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

  The vehicle is provided with a navigation device 15. The navigation device 15 detects the longitudinal acceleration Yg or the lateral acceleration Xg generated in the host vehicle or the yaw rate φ ′ generated in the host vehicle. The navigation device 15 outputs the detected longitudinal acceleration Yg, lateral acceleration Xg, and yaw rate φ ′ to the braking / driving force control unit 8 together with road information. Here, the road information includes road type information indicating the number of lanes and whether the road is a general road or a highway.

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

When the detected vehicle traveling state data has left and right directions, the left direction is the positive direction. That is, the yaw rate φ ′, the lateral acceleration Xg, and the yaw angle φ are positive values when turning left, and the lateral displacement X is a positive value when deviating leftward from the center of the traveling lane. The longitudinal acceleration Yg takes a positive value during acceleration and takes a negative value during deceleration.
Next, a calculation processing procedure performed by the braking / driving force control unit 8 will be described with reference to FIG. This calculation process is executed by a timer interrupt every predetermined sampling time ΔT every 10 msec., For example. Although no communication process is provided in the process shown in FIG. 2, information obtained by the arithmetic process is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.

  First, in step S1, various data are read from each sensor, controller, or control unit. Specifically, the longitudinal acceleration Yg, the lateral acceleration Xg, the yaw rate φ ′ and road information obtained by the navigation device 15, the wheel speeds Vwi, the steering angle δ, the accelerator opening θt, the master cylinder hydraulic pressure detected by the sensors. Pmf, Pmr, direction switch signal, drive torque Tw from the drive torque control unit 12, and yaw angle φ, lateral displacement X, and travel lane curvature β are read from the imaging unit 13.

Subsequently, in step S2, the vehicle speed V is calculated. Specifically, the vehicle speed V is calculated by the following equation (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. For this reason, when the vehicle deviates to the left in the left lane, that is, to the shoulder side, there is a high possibility that the host vehicle 100A will come into contact with these objects. 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 100C is traveling on 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 one lane road is the same as the captured image obtained by the imaging unit 13 of the vehicle 100A traveling on the left lane of the one lane road. Therefore, when it is assumed that the vehicle travels on a general road and an expressway, the existence direction Sout 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 be determined that the degree of safety is also 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 S41, the estimated 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 S42, 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 S42, 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 S43, 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.
Here, based on the longitudinal acceleration Yg obtained in step S1, the first obstacle existence direction Sout obtained in step S3, the departure direction Dout obtained in step S4, and the departure judgment flag Fout obtained in step S5, the departure is made. Determine control details for avoidance.

  For example, when the departure determination flag Fout is ON (Tout <Ts), a departure warning is performed. For example, an alarm is given by sound or display. When the departure determination flag Fout is ON (Tout <Ts), a braking control method for departure avoidance is determined based on the longitudinal acceleration Yg, the first obstacle existence direction Sout, and the departure direction Dout. 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 become large values in the low speed range, and when the vehicle speed V reaches a certain value, it decreases as the vehicle speed V increases, and then reaches a certain vehicle speed V. It becomes a constant value.

Then, based on the target braking hydraulic pressure Pgf for the front wheels, the target braking hydraulic pressure Pgr for the rear wheels considering the front-rear distribution is calculated.
Thus, in step S8, deceleration for avoiding deviation (specifically, target braking hydraulic pressures Pgf, Pgr) is obtained.
Subsequently, in step S9, a target brake hydraulic pressure for each wheel is calculated. In other words, the final braking fluid pressure is calculated based on the presence or absence of the departure avoidance braking control. Specifically, it is calculated as follows.

(1) When the departure determination flag Fout is OFF (Fout = OFF), that is, when the determination result that there is no departure is obtained, as shown in the following equations (5) and (6), the target braking fluid for each wheel The pressure Psi (i = fl, fr, rl, rr) is set to the master cylinder hydraulic pressure 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.

(2) When the departure determination flag Fout is ON (Fout = ON), that is, when a determination result indicating departure is obtained, first, based on the target yaw moment Ms, the front wheel target brake fluid pressure difference ΔPsf and the rear wheel target brake fluid The pressure difference ΔPsr is 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. The 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 fluid pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking fluid pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. 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 based on the braking control method determined in step S7.
Here, the braking control method determined in step S6 will be described.

In step S6, a braking control method is determined based on the longitudinal acceleration Yg, the first obstacle etc. existence direction Sout and the departure direction Dout. With respect to this, the braking control method will be described with respect to the longitudinal acceleration Yg, the first obstacle existence direction Sout, and the deviation direction Dout.
(First Case) When the longitudinal acceleration Yg is larger than 0 (Xg> 0), that is, when the host vehicle is accelerating, the braking control for decelerating the vehicle until the departure determination flag Fout is turned off (hereinafter referred to as “the first case”). Is called deceleration control for deviation avoidance). This departure avoidance deceleration control is performed by applying the same level of braking force to the left and right wheels.

Here, the case where the departure determination flag Fout is changed from ON to OFF is when the braking control for avoiding departure is performed or the driver himself performs an avoidance operation when there is a departure tendency. .
On the other hand, when the longitudinal acceleration Yg is smaller than 0 (Xg <0), that is, when the host vehicle is decelerating, a yaw moment for avoiding the 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.

(Second Case) When the first obstacle etc. existence direction Sout and the departure direction Dout do not match and when the longitudinal acceleration Yg is smaller than 0, the departure avoidance flag Fout is turned off until the departure determination flag Fout is turned off. Perform yaw control.
Here, because the longitudinal acceleration Yg is smaller than 0, the deviation avoidance yaw control is performed using the target yaw moment Ms changed to a small value. For example, the target yaw moment Ms is changed to a small value as follows.

In step S7, the target yaw moment Ms is calculated by the equation (3). By changing the gain K1 in the equation (3) to a gain K1 ′ smaller than the gain K1, the target yaw moment Ms is calculated. Set to a smaller value.
For example, FIG. 10 shows an example of gains K1 and K1 ′ to be used. As shown in FIG. 10, the gains K1 and K1 ′ have large values in the low speed range. When the vehicle speed V reaches a certain value, the gains K1 and K1 ′ decrease with the increase in the vehicle speed V, and then constant when the vehicle speed V reaches a certain value. Value. Then, the gain K1 ′ is set to a value smaller than the gain K1 in the low speed range and the speed increase range. Thus, the target yaw moment Ms is reduced by changing the gain K1 in the equation (3) to the gain K1 ′.

(Third case) When the first obstacle existence direction Sout and the departure direction Dout do not coincide with each other and the longitudinal acceleration Yg is larger than 0, the departure avoidance flag Fout is turned off until the departure determination flag Fout is turned off. Perform yaw control.
Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.
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 (Tout <Tr), departure avoidance deceleration control is performed in addition to departure avoidance yaw control.

(Fourth 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, and the longitudinal acceleration Yg is smaller than 0, The departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Further, when the predicted departure time Tout becomes shorter than the second departure determination threshold value Tr (Tout <Tr), departure avoidance deceleration control is performed in addition to departure avoidance yaw control.
Here, because the longitudinal acceleration Yg is smaller than 0, the departure avoidance yaw control is performed using the target yaw moment Ms changed to a small value, as in the second case.

(Fifth 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 general road and the longitudinal acceleration Yg is greater than 0, The departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Further, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs1) obtained by adding a certain set amount (hereinafter referred to as a first set amount) dTs1 to the first departure determination threshold value Ts. For example, the first set amount dTs1 is less than the first departure determination threshold value Ts (Ts> dTs1).

As a result, when the predicted departure time Tout becomes shorter than the departure determination threshold (Ts + dTs1) (Tout <(Ts + dTs1)), departure avoidance deceleration control is performed. Thereby, when there is a departure tendency, departure avoidance deceleration control is started earlier by the first set amount dTs1, and then departure avoidance yaw control is performed.
In step S6, various braking control methods are determined according to the values of the longitudinal acceleration Yg, the first obstacle existence direction Sout, and the departure direction Dout. In other words, according to the values of the longitudinal acceleration Yg, the first obstacle existence direction Sout, and the departure direction Dout, the departure avoidance yaw control alone or the combination of the departure avoidance yaw control and the departure avoidance deceleration control is avoided. The braking control method for is determined.

In step S9, 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 second to fifth 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 third to fifth cases, the deviation avoidance yaw control and the departure avoidance deceleration control are performed. In this case, the target braking fluid for each wheel is expressed by the following equation (12). The 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
(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 S9. Thus, in step S9, the target braking 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, the target braking of each wheel corresponding to various braking control methods determined according to the values of the longitudinal acceleration Yg, the first obstacle existence direction Sout, and the departure direction Dout. The hydraulic pressure Psi (i = fl, fr, rl, rr) 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 for each wheel calculated in step S9 as a braking fluid pressure command value to the braking fluid pressure controller 7. Output.

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 a direction with a relatively low degree of safety (an obstacle etc. existing 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. 4).
Further, the driver's intention to change the lane is determined based on the deviation direction Dout thus obtained and the direction indicated by the direction switch signal (the blinker lighting side) (step 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.

Then, based on the longitudinal acceleration Yg, the departure determination flag Fout, and the departure direction Dout, the presence / absence of an alarm start for departure avoidance, the presence / absence of braking control for departure avoidance, and the case of performing braking control for departure avoidance A method 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).

  Then, the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel for realizing the braking control method determined based on the longitudinal acceleration Yg, the departure determination flag Fout and the departure direction Dout is calculated, The calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) is output to the brake fluid pressure controller 7 as a brake fluid pressure command value (step S9). 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 and the longitudinal acceleration Yg. Here, the vehicle behavior when the braking control is performed in the first to fifth cases will be described.

  When the host vehicle is accelerating, departure avoidance deceleration control is performed until the departure determination flag Fout is turned off (first case). On the other hand, when the host vehicle is decelerating, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off (the first case). The vehicle avoids the departure by such control for avoiding the departure. On the other hand, the driver can feel the acceleration in the lateral direction or the deceleration in the traveling direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a tendency to depart.

  Further, when the first obstacle etc. existence direction Sout and the departure direction Dout do not coincide with each other and the host vehicle is decelerating, the target yaw smaller than the normal value is set until the departure determination flag Fout is turned OFF. Deviation avoidance yaw control is performed using the moment Ms (second case). Thereby, the own vehicle avoids deviation. On the other hand, the driver can feel the acceleration in the lateral direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a departure tendency.

  When the first obstacle etc. existence direction Sout and the departure direction Dout do not coincide with each other and the host vehicle is accelerating, the target yaw moment Ms having a normal value is set until the departure determination flag Fout is turned off. Is used to perform deviation avoidance yaw control. Further, when the predicted departure time Tout becomes smaller than the second departure determination threshold Tr (Tout <Tr), departure avoidance deceleration control is performed in addition to the departure avoidance yaw control (the third case) ). The vehicle avoids the departure by such control for avoiding the departure. On the other hand, the driver can feel the acceleration in the lateral direction or the deceleration in the traveling direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a tendency to depart.

  Further, when the first obstacle existence direction Sout and the departure direction Dout coincide with each other and the road type R is a general road and the host vehicle is decelerating, until the departure determination flag Fout is turned OFF, Deviation avoidance yaw control is performed using a target yaw moment Ms smaller than a normal value. Further, when the predicted departure time Tout becomes smaller than the second departure determination threshold value Tr (Tout <Tr), departure avoidance deceleration control is performed in addition to departure avoidance yaw control (the fourth Case). The vehicle avoids the departure by such control for avoiding the departure. On the other hand, the driver can feel the acceleration in the lateral direction or the deceleration in the traveling direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a tendency to depart.

  Further, when the first obstacle existence direction Sout and the departure direction Dout coincide, the road type R is a general road, and the host vehicle is accelerating, the departure determination threshold value (Ts + dTs1). When the predicted departure time Tout becomes smaller (Tout <(Ts + dTs1)), the departure avoidance deceleration control is performed, and when the predicted departure time Tout becomes smaller than the first departure determination threshold value Ts ( Deviation avoidance yaw control is performed using Tout <Ts) and the target yaw moment Ms having a normal value (the fifth case). The vehicle avoids the departure by such control for avoiding the departure. On the other hand, the driver can feel the acceleration in the lateral direction or the deceleration in the traveling direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a tendency to depart.

  In the case where the first obstacle existence direction Sout and the departure direction Dout coincide with each other and the road type R is a general road, as shown in FIG. 11, the left side is a shoulder A and the right side is an oncoming lane ( In the case where the host vehicle 100 is traveling on one lane on one side such as the center lane LI5 side, the host vehicle 100 (the host vehicle 100 in the uppermost position in FIG. 11) is in the left direction or the host vehicle (in FIG. 11). This is a case where the vehicle 100) at the intermediate position tends to deviate in the right direction.

Next, the effect in this 1st Embodiment is demonstrated.
As described above, when there is a tendency to deviate while the host vehicle is decelerating, the target yaw moment used in the deviation avoidance yaw control is set to a small value (for example, the second case).
For example, when the vehicle is decelerating, the driver may feel that the possibility of deviating is low. In such a case, if a yaw moment of a size normally used is applied to the vehicle, The driver feels uncomfortable and annoying. For this reason, if the vehicle has a tendency to deviate while the vehicle is decelerating, the yaw control for avoiding the deviation by reducing the target yaw moment makes the vehicle behavior uncomfortable or annoying to the driver. Can be prevented.

Further, as described above, when there is a departure tendency while the host vehicle is accelerating, departure avoidance deceleration control is first performed (for example, the fifth case). That is, even when departure avoidance yaw control is performed, departure avoidance deceleration control is performed before that.
For this reason, when there is a tendency to deviate while the host vehicle is accelerating, first performing the deviating avoidance deceleration control and then performing the deviating avoidance yaw control, the driver feels uncomfortable and annoying. It can prevent giving.

On the other hand, when there is a tendency to deviate while the host vehicle is accelerating, the deviation avoidance yaw control is performed and then the departure avoidance deceleration control is performed (for example, the third case).
By performing the departure avoidance deceleration control, even if an obstacle or the like is approached, the degree can be reduced to prevent contact.
Thus, by determining the control details of the departure avoidance deceleration control and the departure avoidance yaw control based on the acceleration / deceleration of the host vehicle, it is possible to prevent the driver from feeling uncomfortable or bothering. it can.

Further, as described above, when the host vehicle tends to deviate while traveling on a general road, the deviating avoidance yaw control is performed, and then deviating avoidance deceleration control is performed (for example, the above-mentioned first control). Case 4).
For example, a deviation from a shoulder or an opposite lane on a general road has a high possibility of approaching an obstacle or a pedestrian, so even when the deviation avoidance yaw control is performed, immediately before the departure (0 <Tout <Tr ) Can be prevented by performing deceleration control for deviation avoidance. Furthermore, if the departure avoidance deceleration control is performed only immediately before the departure (0 <Tout <Tr) in this way, the control frequently does not intervene, so that it is possible to prevent annoying the driver. .

  Next, a second embodiment will be described. This second embodiment is also a vehicle provided with a vehicle departure prevention device. FIG. 12 shows the configuration of the vehicle according to the second embodiment. As shown in FIG. 12, an ACC radar 31, rear side obstacle monitoring radars 32 and 33, and side obstacle monitoring radars 34 and 35 are provided. Note that other configurations of the vehicle of the second embodiment are the same as those of the first embodiment unless otherwise specified.

  Here, the ACC radar 31 obtains information about a vehicle or an obstacle ahead of the lane adjacent to the own lane. Specifically, the ACC radar 31 obtains the presence / absence of the preceding vehicle, the relative distance Lfr and the relative speed Vfr with respect to the preceding vehicle, and the like. The ACC radar 31 outputs the presence / absence of the preceding vehicle, the relative distance Lfr, and the relative speed Vfr to the braking / driving force control unit 8.

  The rear side obstacle monitoring radars 32 and 33 obtain information on the vehicle or the obstacle on the rear side of the host vehicle. Specifically, the rear side obstacle monitoring radars 32 and 33 obtain the relative distance Lbsr and the relative speed Vbsr with respect to the presence or absence of the rear side vehicle or the like, the rear side vehicle or the like. The rear side obstacle monitoring radars 32 and 33 output the presence / absence of the rear side vehicle and the like, the relative distance Lbsr, and the relative speed Vbsr to the braking / driving force control unit 8.

  The side obstacle monitoring radars 34 and 35 obtain information on a vehicle or an obstacle on the side of the host vehicle. Specifically, the side obstacle monitoring radars 34 and 35 obtain the presence / absence of the side vehicle and the like, the relative distance Lsr to the side vehicle and the like, and the relative speed Vsr. The side obstacle monitoring radars 34 and 35 output the presence / absence of these side vehicles, the relative distance Lsr, and the relative speed Vsr to the braking / driving force control unit 8.

Next, based on such a configuration, a calculation processing procedure performed by the braking / driving force control unit 8 will be described. The calculation processing procedure is also substantially the same as the calculation processing procedure (FIG. 2) of the first embodiment, and particularly different parts will be described.
That is, first, in step S1, signals from the ACC radar 31, rear side obstacle monitoring radars 32 and 33, side obstacle monitoring radars 34 and 35, and rear obstacle monitoring radar 36 are obtained. Read.

Subsequently, in step S2, the vehicle speed V is calculated in the same manner as in the first embodiment. In step S3, the traveling environment is determined. This process of determining the driving environment is a process specific to the second embodiment.
In the first embodiment, the type of road on which the host vehicle is traveling and the traveling lane of the host vehicle are detected, and the presence direction of the first obstacle and the like is obtained based on the detection result. In contrast, in the second embodiment, the direction of lower safety is obtained based on the presence of other vehicles and obstacles obtained by the ACC radar 31 or the like.

  That is, when it is determined that the left direction is low in safety when viewed from the own vehicle based on the information obtained from the ACC radar 31 (information on other vehicles and obstacles existing ahead), the direction is determined based on the safety level. If the direction of the vehicle is low (hereinafter referred to as the second obstacle presence direction) Aout (Aout = left) and the right direction is determined to be low when viewed from the host vehicle, the direction is designated as the second obstacle, etc. The existence direction is Aout (Aout = right). For example, when there is another vehicle or an obstacle in front of the host vehicle, if the vehicle deviates to the right, the possibility of coming into contact with the other vehicle is increased. An equal existence direction Aout is assumed (Aout = right).

When it is determined that the safety degree is low in both directions when viewed from the host vehicle, both directions are set as the second obstacle existence direction Aout (Aout = both).
Further, based on information obtained from the obstacle monitoring radars 32 and 33 on the rear side (information on other vehicles and obstacles existing on the rear side), the left direction is low when viewed from the own vehicle. When it is determined, the direction is determined to be a direction with a low safety level (hereinafter referred to as a third obstacle or the like) RSout (RSout = left), and the right direction is determined to have a low safety level as viewed from the host vehicle. , The direction is the third obstacle existence direction RSout (RSout = right). That is, for example, when an overtaking vehicle that is overtaking the host vehicle is detected on the right lane side, the right direction is determined to be the third obstacle existence direction RSout (RSout = right).

When both directions are low in safety when viewed from the host vehicle, both directions are determined as the third obstacle existence direction RSout (RSout = both).
Also, based on the information obtained from the side obstacle monitoring radars 34 and 35 (information on other vehicles and obstacles present on the side), it is determined that the left direction is low in safety when viewed from the own vehicle. In this case, when the direction is determined to be a direction with a low safety level (hereinafter referred to as a fourth obstacle or the like direction) SDout (SDout = left), and the right direction as viewed from the host vehicle is determined to have a low safety level, The direction is defined as a fourth departure direction SDout (SDout = right). That is, for example, when it is determined that another vehicle is running in the right lane, the right direction is set as the fourth obstacle existence direction SDout (SDout = right).

Further, the fourth obstacle presence direction SDout may be finally determined on condition that another vehicle or an obstacle is moving at a speed similar to the own vehicle speed. Thus, for example, when it is determined that another vehicle is running in the right lane and the speed of the other vehicle is equal to the own vehicle speed, the right direction is set as the fourth obstacle existence direction SDout (SDout = Right).
When both directions are low in safety when viewed from the host vehicle, both directions are determined to be the fourth obstacle etc. existence direction SDout (SDout = both).

The process of step S3 is performed as described above.
Subsequently, in steps S4 to S9, as in the first embodiment, determination of lane departure tendency, determination of driver's intention to change lane, determination of control method, calculation of target yaw moment, departure avoidance The deceleration of the vehicle and the target brake fluid pressure of each wheel are calculated. The above is the arithmetic processing by the braking / driving force control unit 8 in the second embodiment.
Here, based on the second and fourth obstacle existence directions Aout, RSout, SDout obtained in step S3, the braking control method is determined in the same manner as in the first embodiment. Here, the braking control method will be described for each case.
The relationship between the departure direction Dout and the second obstacle existence direction Aout is as follows (sixth case to tenth case).

(Sixth Case) When the departure direction Dout does not coincide with the second obstacle etc. existence direction Aout and when the longitudinal acceleration Yg is smaller than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Here, because the longitudinal acceleration Yg is smaller than 0, the departure avoidance yaw control is performed using the target yaw moment Ms changed to a small value, as in the second case.

(Seventh Case) When the departure direction Dout does not coincide with the second obstacle etc. existence direction Aout and the longitudinal acceleration Yg is larger than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Further, when the predicted departure time Tout becomes shorter than the second departure determination threshold value Tr (Tout <Tr), departure avoidance deceleration control is performed in addition to departure avoidance yaw control.
Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value as in the first case.

(Eighth Case) When the departure direction Dout and the second obstacle existence direction Aout coincide with each other and the longitudinal acceleration Yg is smaller than 0, the departure avoidance flag Fout is turned off until the departure determination flag Fout is turned off. Perform yaw control.
Here, the lane departure tendency is determined using a departure determination threshold value (Ts + dTs2) obtained by adding a certain set amount (hereinafter referred to as a second set amount) dTs2 to the first departure determination threshold value Ts. . Thereby, when the departure prediction time Tout becomes shorter than the departure determination threshold value (Ts + dTs2) (Tout <(Ts + dTs2)), departure avoidance yaw control is started. Thereby, the start timing of the departure avoidance yaw control is advanced by the second set amount dTs2.
Here, because the longitudinal acceleration Yg is smaller than 0, the deviation avoidance yaw control is performed using the target yaw moment Ms changed to a small value as in the second case.

(Ninth Case) When the departure direction Dout is coincident with the second obstacle existence direction Aout and the longitudinal acceleration Yg is greater than 0, the departure avoidance flag Fout is turned off until the departure determination flag Fout is turned off. Perform yaw control.
Here, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs3) obtained by adding a certain set amount (hereinafter referred to as a third set amount) dTs3 to the first departure determination threshold value Ts. For example, the third set amount dTs3 is a value smaller than the first departure determination threshold value Ts (Ts> dTs3).

As a result, when the predicted departure time Tout becomes shorter than the departure determination threshold (Ts + dTs3) (Tout <(Ts + dTs3)), departure avoidance yaw control is started. Thereby, the start timing of the deviation avoidance yaw control is advanced by the third set amount dTs3.
Here, since the longitudinal acceleration Yg is greater than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.

(Tenth case) When the departure direction Dout and the second obstacle existence direction Aout coincide with each other and the longitudinal acceleration Yg is larger than 0, the departure avoidance flag is used until the departure determination flag Fout is turned off. Perform yaw control.
Here, the lane departure tendency is determined using a departure determination threshold value (Ts + dTs4) obtained by adding a certain set amount (hereinafter referred to as a fourth set amount) dTs4 to the first departure determination threshold value Ts. As a result, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs4) (Tout <(Ts + dTs4)), departure avoidance yaw control is started.

  Further, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs5) obtained by adding a certain set amount (hereinafter referred to as a fifth set amount) dTs5 to the first departure determination threshold value Ts. For example, the fifth set amount dTs5 is set to a value smaller than the fourth set amount dTs4 (dTs4> dTs5). As a result, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs5) (Tout <(Ts + dTs5)), further departure avoidance deceleration control is performed.

By such control, departure avoidance yaw control is started at a timing earlier by the fourth set amount dTs4, and thereafter departure avoidance deceleration control is started at a timing earlier by the fifth set amount dTs5.
Here, FIG. 13 shows the vehicle behavior when the deviation avoidance yaw control is performed in the eighth to tenth cases. The eighth to tenth cases are cases where the departure direction Dout and the second obstacle existence direction Aout coincide. That is, as shown in FIG. 13, the own vehicle 100 tends to deviate in the right direction, and another vehicle 101 exists in that direction. In this case, deviation avoidance yaw control is performed at a predetermined timing. In some cases, departure avoidance deceleration control is performed at a predetermined timing.

Note that the second to fifth set amounts dTs2, dTs3, dTs4, dTs5 and the deceleration by the deviation avoidance deceleration control may be set based on the distance from the obstacle ahead. For example, since the ACC radar 31 can obtain the distance to the obstacles ahead, the second to fifth settings are made based on the distance to the obstacles ahead obtained by the ACC radar 31. The quantity dTs2, dTs3, dTs4, dTs5 and the deceleration are set.
For example, as the distance is shorter, the second to fifth set amounts dTs2, dTs3, dTs4, dTs5 and the deceleration are increased. In such a case, the start timing of the departure avoidance yaw control is earlier as the distance is shorter. Also, the shorter the distance, the greater the deceleration due to departure avoidance deceleration control.

Next, the relationship between the departure direction Dout and the third obstacle existence direction RSout will be described (an eleventh case to a fourteenth case).
(Eleventh case) When the departure direction Dout does not coincide with the third obstacle existence direction RSout and the longitudinal acceleration Yg is smaller than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Here, because the longitudinal acceleration Yg is smaller than 0, the departure avoidance yaw control is performed using the target yaw moment Ms changed to a small value, as in the second case.

(Twelfth case) When the departure direction Dout does not coincide with the third obstacle existence direction RSout and the longitudinal acceleration Yg is larger than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.

(Thirteenth case) When the departure direction Dout and the third obstacle existence direction RSout coincide with each other and the longitudinal acceleration Yg is smaller than 0, the departure avoidance flag is used until the departure determination flag Fout is turned off. Perform yaw control.
Here, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs6) obtained by adding a certain set amount (hereinafter referred to as a sixth set amount) dTs6 to the first departure determination threshold value Ts. For example, the sixth set amount dTs6 is smaller than the first departure determination threshold value Ts (Ts> dTs6).
Accordingly, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs6) (Tout <(Ts + dTs6)), departure avoidance yaw control is started. Thereby, the start timing of the deviation avoidance yaw control is advanced by the sixth set amount dTs6.

Here, the deviation avoidance yaw control is performed using the target yaw moment Ms changed to a small value as in the second case because the longitudinal acceleration Yg is smaller than 0.
In step S7, the target yaw moment Ms is calculated by the equation (3). Here, the gains K1 and K2 in the equation (3) may be set to different values. For example, the gain K1 is set to the gain (K1 + dK1), and the gain K2 is set to the gain (K2 + dK2). Here, dK1 and dK2 are predetermined values for changing the gains K1 and K2. As a result, when the departure prediction time Tout becomes shorter than the departure determination threshold (Ts + dTs6) (Tout <(Ts + dTs6)), the target yaw moment Ms obtained using the gains (K1 + dK1), (K2 + dK2). Perform yaw control for avoidance by

  When the target yaw moment Ms is changed to a large value as described above, the setting of the target yaw moment Ms may be limited by the maximum value Mmax. That is, even when the predetermined values dK1, dK2 are determined according to a certain condition, if the target yaw moment Ms obtained using the predetermined values dK1, dK2 exceeds the maximum value Mmax, the predetermined value The target yaw moment Ms is set to the maximum value Mmax regardless of dK1 and dK2.

  (14th Case) When the departure direction Dout and the third obstacle existence direction RSout coincide with each other and the longitudinal acceleration Yg is greater than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.

Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.
A lane departure tendency is determined using a departure determination threshold value (Ts + dTs7) obtained by adding a predetermined amount (hereinafter referred to as a seventh setting amount) dTs7 to the first departure determination threshold value Ts. For example, the seventh set amount dTs7 is smaller than the first departure determination threshold value Ts (Ts> dTs7). Thereby, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs7) (Tout <(Ts + dTs7)), departure avoidance deceleration control is performed.

Thereby, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs7) (Tout <(Ts + dTs7)), departure avoidance deceleration control is performed. Thereby, when there is a departure tendency, the departure avoidance deceleration control is started earlier by the seventh set amount dTs7, and then the departure avoidance yaw control is performed.
In the fourteenth case, the target yaw moment Ms may be set as described in the thirteenth case.

  Here, FIG. 14 shows the vehicle behavior when the yaw control for deviation avoidance is performed in the thirteenth case and the fourteenth case. The thirteenth case and the fourteenth case are cases where the departure direction Dout and the third obstacle existence direction Sout coincide. That is, as shown in FIG. 14, the host vehicle 100 tends to deviate in the right direction, and another vehicle 101 following the host vehicle 100 exists in the lane on the right side. In this case, deviation avoidance yaw control is performed at a predetermined timing. In some cases, departure avoidance deceleration control is performed at a predetermined timing.

Next, the relationship between the departure direction Dout and the fourth obstacle etc. existence direction SDout will be described (fifteenth case to eighteenth case).
(15th Case) When the departure direction Dout does not coincide with the fourth obstacle existence direction SDout and the longitudinal acceleration Yg is smaller than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Here, because the longitudinal acceleration Yg is smaller than 0, the departure avoidance yaw control is performed using the target yaw moment Ms changed to a small value, as in the second case.

(Sixteenth case) When the departure direction Dout does not coincide with the fourth obstacle existence direction SDout and the longitudinal acceleration Yg is greater than 0, the estimated departure time is longer than the first departure determination threshold value Ts. When Tout becomes small (Tout <Ts), departure avoidance yaw control is started. Then, the departure avoidance yaw control is performed until the departure determination flag Fout is turned off.
Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.

  A lane departure tendency is determined using a departure determination threshold value (Ts + dTs8) obtained by adding a certain set amount (hereinafter referred to as an eighth set amount) dTs8 to the first departure determination threshold value Ts. For example, the eighth set amount dTs8 is a value smaller than the first departure determination threshold value Ts (Ts> dTs8). Thereby, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs8) (Tout <(Ts + dTs8)), departure avoidance deceleration control is performed.

  Thereby, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs8) (Tout <(Ts + dTs8)), departure avoidance deceleration control is performed. Thereby, when there is a departure tendency, departure avoidance deceleration control is started earlier by the eighth set amount dTs8, and then departure avoidance yaw control is performed.

(Seventeenth case) When the departure direction Dout coincides with the fourth obstacle existence direction SDout and the longitudinal acceleration Yg is smaller than 0, the departure avoidance flag Fout is turned off until the departure determination flag Fout is turned off. Perform yaw control.
Here, because the longitudinal acceleration Yg is smaller than 0, the departure avoidance yaw control is performed using the target yaw moment Ms changed to a small value, as in the second case.

Further, here, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs9) obtained by adding a predetermined set amount (hereinafter referred to as a 9th set amount) dTs9 to the first departure determination threshold value Ts. . Thereby, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs9) (Tout <(Ts + dTs9)), departure avoidance yaw control is started.
Further, when the predicted departure time Tout becomes shorter than the first departure determination threshold value Ts (Tout <Ts), departure avoidance deceleration control is performed. Thus, departure avoidance yaw control is started as early as the ninth set amount dTs9, and thereafter departure avoidance yaw control is performed in addition to the departure avoidance yaw control.

(Eighteenth case) When the departure direction Dout is coincident with the fourth obstacle existence direction SDout and the longitudinal acceleration Yg is greater than 0, departure avoidance is performed until the departure determination flag Fout is turned OFF. Performs deceleration control.
Here, since the longitudinal acceleration Yg is larger than 0, the value is maintained without changing the target yaw moment Ms to a small value, as in the first case.
Further, here, a lane departure tendency is determined using a departure determination threshold value (Ts + dTs10) obtained by adding a certain set amount (hereinafter referred to as a 10th set amount) dTs10 to the first departure determination threshold value Ts. . Thus, when the predicted departure time Tout becomes shorter than the departure determination threshold value (Ts + dTs10) (Tout <(Ts + dTs10)), departure avoidance deceleration control is started.

Further, when the predicted departure time Tout becomes shorter than the first departure determination threshold value Ts (Tout <Ts), departure avoidance yaw control is performed. Thus, the departure avoidance deceleration control is started 10 minutes earlier by the tenth set amount dTs, and then this departure avoidance yaw control is performed.
Here, FIG. 15 shows the vehicle behavior when deviation avoidance yaw control is performed in the seventeenth case and the eighteenth case. The seventeenth case and the eighteenth case are cases where the departure direction Dout and the fourth obstacle etc. existence direction SDout coincide. That is, as shown in FIG. 15, the host vehicle 100 tends to deviate in the right direction, and there is another vehicle 101 running alongside the host vehicle 100 in the lane on the right side. In this case, departure avoidance deceleration control and departure avoidance yaw control are started at a predetermined timing.

  The target braking fluid pressure Psi (i = fl, fr, rl, rr) for each wheel is determined in the same manner as in the first embodiment. That is, the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated so as to realize the braking control method in the sixth to 18th cases. Then, the calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel 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, control for avoiding deviation is performed based on the control content (control content in the sixth to eighteenth cases) determined based on the second and fourth obstacle existence directions Aout, RSout, SDout. Is done. Thereby, the own vehicle avoids deviation. On the other hand, the driver can feel the acceleration in the lateral direction or the deceleration in the traveling direction by the departure avoiding operation of the vehicle, and can know that the own vehicle is in a tendency to depart.

Next, the effect in this 2nd Embodiment is demonstrated.
Similar to the first embodiment described above, if the vehicle tends to deviate while the host vehicle is decelerating, the target yaw moment used in the deviation avoidance yaw control is set to a small value (for example, the sixth embodiment). Case). Thereby, it is possible to prevent the vehicle behavior from being disturbed, and further to prevent the driver from feeling uncomfortable and troublesome.

Similarly to the first embodiment described above, when there is a tendency to deviate while the host vehicle is accelerating, deviating avoidance deceleration control is first performed (for example, the fourteenth case). Thereby, it is possible to prevent the driver from feeling uncomfortable or troublesome.
Further, in the second embodiment, when there is another vehicle in the departure direction, the departure avoidance deceleration control is first performed (for example, the ninth case). Thereby, it can prevent that the own vehicle contacts other vehicles. It is also possible to prevent the driver of other vehicles from feeling uncomfortable.

Further, when there is another vehicle in the departure direction, at least the departure avoidance deceleration control (for example, the seventeenth and eighteenth cases) is performed on the other vehicle regardless of before and after the departure avoidance yaw control. It is possible to prevent the host vehicle from coming into contact.
Further, as in the first embodiment described above, when there is a departure tendency while the host vehicle is accelerating, the departure avoidance yaw control is performed and then the departure avoidance deceleration control is performed ( For example, the tenth case). As a result, even when the vehicle behavior is disturbed, the vehicle behavior disturbance can be suppressed by performing the departure avoidance deceleration control. Moreover, even if it approaches an obstacle etc., the approach degree can be lowered | hung and contact can be prevented.

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 vehicle deceleration control), the operation sequence thereof, and the control amounts thereof (the magnitude of the yaw moment and the magnitude of the deceleration) are specifically described based on the determination of the acceleration / deceleration of the vehicle. However, it goes without saying that the present invention is not limited to this.

For example, in the above-described embodiment, there is no particular reference to the case where the control amount (deceleration) for departure avoidance deceleration control is determined based on the acceleration / deceleration of the vehicle, but the control amount for departure avoidance deceleration control ( (Deceleration) may be determined based on the acceleration / deceleration of the vehicle. For example, when the vehicle is decelerating, the control amount (deceleration) of the departure avoidance deceleration control may be reduced.
Further, in the above-described embodiment, the brake structure is described as a brake structure using fluid pressure. However, it goes without saying that the present invention is not limited to this. For example, an electric friction brake that presses the friction material against the rotating body of the wheel side member by an electric actuator, a regenerative brake that generates an electric braking action, or a power generation brake may be used. Also, an engine brake that performs braking control by changing the valve timing of the engine, a speed change brake that acts like an engine brake by changing the speed ratio, or an air brake may be used.

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.

As described above, when the longitudinal acceleration Yg is smaller than 0, the target yaw moment Ms is changed to a small value. In this case, by changing the gains K1, K3, K4, and K5 in the equation (13) to gains K1 ′, K3 ′, K4 ′, and K5 ′ that are smaller than the gains K1, K3, K4, and K5, respectively, The moment Ms is set to a small value.
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 description of the above-described embodiment, the braking / driving force control unit 8 shares the amount of yaw moment applied to the host vehicle and the deceleration of the host vehicle, the start timing of the yaw moment application, and the host vehicle. Setting means for setting at least one of the deceleration start timings based on the acceleration / deceleration of the host vehicle is realized. That is, the determination process of the braking control method performed in step S6 shown in FIG. 2 of the braking / driving force control unit 8 realizes the setting means.
The ACC radar 31, rear side obstacle monitoring radars 32 and 33, and side obstacle monitoring radars 34 and 35 implement obstacle detection means for detecting obstacles around the host vehicle. ing.

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 a characteristic view which shows the characteristic of gain K1, K1 'used for calculation of the target yaw moment Ms. It is the figure used for description of the vehicle behavior at the time of the 5th case. It is a schematic block diagram which shows 2nd Embodiment of the vehicle carrying the lane departure prevention apparatus of this invention. It is the figure used for description of the vehicle behavior in the 8th thru | or 10th case. It is the figure used for description of the vehicle behavior in the 13th case and the 14th case. It is the figure used for description of the vehicle behavior in the 17th case and the 18th case.

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 31 ACC radar 32, 33 Rear side obstacle monitoring radar 34, 35 Side obstacle monitoring radar

Claims (3)

Lane departure determination means for determining the presence or absence of a departure tendency from the traveling lane of the host vehicle;
Target yaw moment calculating means for calculating a target yaw moment that is a target value of the yaw moment to be given to the own vehicle based on the lateral displacement from the center of the traveling lane of the own vehicle;
When the lane departure determining means determines that there is a tendency to deviate from the traveling lane of the host vehicle, the left and right wheels according to the target yaw moment calculated by the target yaw moment calculating means at a preset yaw moment applying timing A yaw moment applying means for generating a braking force difference and applying a yaw moment to the host vehicle,
Acceleration / deceleration detecting means for detecting acceleration / deceleration of the own vehicle;
Obstacle detection means for detecting obstacles around the vehicle;
When the acceleration / deceleration of the own vehicle detected by the acceleration / deceleration detecting means is a deceleration and the obstacle detecting means detects an obstacle, the acceleration / deceleration of the own vehicle is not reduced by the target yaw moment. Target yaw moment changing means for changing to a smaller value than the case,
A lane departure prevention apparatus comprising: A departure direction determination means for determining a lane departure direction of the host vehicle;
Obstacle presence direction detection means for detecting the presence direction of the obstacle detected by the obstacle detection means with respect to the host vehicle;
The acceleration / deceleration of the host vehicle detected by the acceleration / deceleration detection means is a deceleration, and the lane departure direction determined by the departure direction determination means coincides with the obstacle presence direction detected by the obstacle presence direction detection means. A timing changing means for changing the yaw moment application timing to an earlier timing than when they do not match;
Lane departure prevention apparatus according to claim 1, characterized in that it comprises a. The target yaw moment calculating means calculates the target yaw moment by multiplying the lateral displacement by a gain,
As the vehicle speed increases, the gain changes from a section having a constant value at a large value to a section having a constant value at a small value via a decreasing section.
When the acceleration / deceleration of the own vehicle detected by the acceleration / deceleration detecting means is a deceleration and the obstacle detecting means detects an obstacle, the target yaw moment changing means When the vehicle speed is not a deceleration, the gain in the section where the vehicle speed is a constant value at a large value and the section where the vehicle speed decreases is changed to a small value, and the target yaw moment is changed to a small value. The lane departure prevention apparatus according to claim 1 or 2.

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