JP2006306204A - Lane deviation preventing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a vehicle from deviating from a travelling lane caused by tuck in behavior. <P>SOLUTION: A lane deviation preventing device predicts and detects a rapid turn (tuck in behavior) of its own vehicle to turn to inward of the curve due to variation of acceleration/deceleration operation of the own vehicle during turning travel on a curved road (step S3, step S4), and when the device predicts and detects the tendency of lane deviation resulting from the rapid turn (step S5), the device imposes a yaw moment to prevent the own vehicle from deviating from the travelling lane by considering the amount of the rapid turn when the rapid turn behavior is actually performed (step S6, step S7). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

As a lane departure prevention device, when the vehicle tends to deviate from the driving lane, braking control that combines yaw control and deceleration control, that is, a deviation that decelerates the vehicle while applying a yaw moment to the vehicle based on the estimated departure amount An apparatus for performing avoidance control has been proposed (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-112540

  As shown in FIG. 8A, when the vehicle 100 is turning on a curve (or during steering operation) and the accelerator is turned off as shown in FIG. 8B, the vehicle weight (center of gravity) suddenly moves forward. The so-called tuck-in behavior occurs when the vehicle 100 is moved, and the vehicle 100 is cut inside the turn. Due to such vehicle behavior, the vehicle may subsequently deviate from the travel lane. However, in the conventional lane departure prevention device, such a tuck-in behavior occurs, and if the yaw angle of the vehicle does not change significantly, the lane departure determination is not made. The yaw moment applied to avoid lane departure also becomes a large value. At this time, the behavior change of the vehicle also increases, which gives the driver a sense of incongruity.

If the accelerator is turned on while the vehicle is turning on a curve, the vehicle weight (center of gravity) suddenly moves, so-called power oversteer behavior occurs, and the vehicle cuts into the inside of the turn due to this power oversteer behavior. It will end up.
The present invention has been made in view of the above-described problem, and prevents lane departure without causing the driver to feel uncomfortable without causing the vehicle to deviate from the traveling lane due to tack-in behavior or power oversteer behavior. The purpose is to provide a device.

  The lane departure prevention apparatus according to the first aspect of the invention predicts and detects the inward turning behavior of the own vehicle caused by the acceleration / deceleration operation of the own vehicle that is turning around the curve, and the When the deviation tendency of the own vehicle from the traveling lane is predicted and detected, a yaw moment is applied to the own vehicle for avoiding the deviation of the own vehicle from the traveling lane in consideration of the actual cutting behavior.

  The lane departure prevention apparatus according to the first aspect of the invention predicts and detects the inward turning behavior of the own vehicle caused by the acceleration / deceleration operation of the own vehicle that is turning around the curve, and the By predicting and detecting the deviation tendency of the vehicle from the driving lane, if the vehicle is likely to deviate from the driving lane due to so-called tuck-in behavior or power oversteer behavior, the yaw moment assumed by the cutting behavior is taken into consideration By giving the vehicle a yaw moment for avoiding the vehicle from deviating from the driving lane, the vehicle can be made faster before the tack-in behavior or the power oversteer behavior occurs or in the initial state. In addition, it is possible to prevent the vehicle from deviating from the traveling lane with a small control amount.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
The embodiment is a rear wheel drive vehicle equipped with the lane departure prevention apparatus according to the present invention. This rear-wheel drive vehicle is equipped with an automatic transmission and a conventional differential gear, and a braking device capable of independently controlling the braking force of the left and right wheels for both the front and rear wheels.

FIG. 1 is a schematic configuration diagram showing the present embodiment.
In the figure, reference numeral 1 is a brake pedal, 2 is a booster, 3 is a master cylinder, and 4 is a reservoir. Normally, the brake fluid pressure boosted by the master cylinder 3 according to the amount of depression of the brake pedal 1 by the driver is shown. It supplies to each wheel cylinder 6FL-6RR of each wheel 5FL-5RR. Further, a braking fluid pressure control unit 7 is interposed between the master cylinder 3 and each wheel cylinder 6FL-6RR, and the braking fluid pressure control unit 7 controls the braking fluid pressure of each wheel cylinder 6FL-6RR. Individual control is also possible.

  The braking fluid pressure control unit 7 uses a braking fluid pressure control unit used for antiskid control and traction control, for example. The brake fluid pressure control unit 7 can control the brake fluid pressure of each of the wheel cylinders 6FL to 6RR independently, but when a brake fluid pressure command value is input from the braking / driving force control unit 8 described later, The brake fluid pressure is controlled according to the brake fluid pressure command value.

For example, the brake fluid pressure control unit 7 includes an actuator in the hydraulic pressure supply system. Examples of the actuator include a proportional solenoid valve capable of controlling each wheel cylinder hydraulic pressure to an arbitrary braking hydraulic pressure.
The vehicle is provided with a drive torque control unit 12. The drive torque control unit 12 controls the drive torque to the rear wheels 5RL and 5RR which are drive wheels by controlling the operating state of the engine 9, the selected gear ratio of the automatic transmission 10, and the throttle opening of the throttle valve 11. To do. The drive torque control unit 12 controls the operating state of the engine 9 by controlling the fuel injection amount and ignition timing, and simultaneously controlling the throttle opening. The drive torque control unit 12 outputs the value of the drive torque Tw used for control to the braking / driving force control unit 8.

The drive torque control unit 12 can control the drive torque of the rear wheels 5RL and 5RR independently. However, when a drive torque command value is input from the braking / driving force control unit 8, the drive torque is controlled. Drive wheel torque is also controlled according to the command value.
In addition, this vehicle is provided with an imaging unit 13 with an image processing function. The imaging unit 13 is provided for detecting the position of the host vehicle in the traveling lane for detecting the lane departure tendency of the host vehicle. For example, the imaging unit 13 is configured to capture an image with a monocular camera including a CCD (Charge Coupled Device) camera. This imaging part 13 is installed in the front part of the vehicle.

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

In the present invention, the lane marker may be detected by detection means other than image processing. For example, the lane marker may be detected by a plurality of infrared sensors attached to the front of the vehicle, and the traveling lane may be detected based on the detection result.
Further, the present invention is not limited to the configuration in which the traveling lane is determined based on the white line. In other words, if there is no white line (lane marker) on the road to recognize the driving lane, the information on the road shape and surrounding environment obtained by image processing and various sensors, the driving range suitable for driving and driving A person may estimate the travel range where the vehicle should travel and determine the travel lane. For example, when there is no white line on the runway and both sides of the road are separated, the asphalt portion of the runway is determined as the travel lane. Moreover, what is necessary is just to determine a driving lane in consideration of the information, when there are a guardrail, a curb, etc.

Further, the traveling lane curvature β may be calculated based on a steering angle δ of the steering wheel 21 described later.
The vehicle is provided with a navigation device 14. The navigation device 14 detects the longitudinal acceleration Yg or lateral acceleration Xg generated in the host vehicle or the yaw rate φ ′ generated in the host vehicle. The navigation device 14 outputs the detected longitudinal acceleration Yg, lateral acceleration Xg, and yaw rate φ ′ to the braking / driving force control unit 8 together with road information. Here, the road information includes road type information indicating the number of lanes and whether the road is a general road or a highway.

Each value may be detected by a dedicated sensor. That is, the longitudinal acceleration Yg and the lateral acceleration Xg may be detected by the acceleration sensor, and the yaw rate φ ′ may be detected by the yaw rate sensor.
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, lateral acceleration Xg, yaw rate φ ′ and road information obtained by the navigation device 14, road speed Vwi, steering angle δ, accelerator opening θt, master cylinder hydraulic pressure detected by each sensor 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. For example, when an ABS (Anti-lock Brake System) control or the like is operating, an estimated vehicle speed estimated in the ABS control is used as the vehicle speed V. A value used for navigation information in the navigation device 14 may be used as the vehicle speed V.
Subsequently, in step S3, the vehicle behavior change is determined. Specifically, a tuck-in behavior that occurs when the vehicle suddenly decelerates during a turning motion is detected as the vehicle behavior change.

The tuck-in behavior is that when the accelerator is turned off, the vehicle is suddenly braked and the load moves in front of the vehicle, so that the friction circle radius of the front wheels is increased, thereby increasing the cornering force. Is a phenomenon of sudden turning.
Such tuck-in behavior is estimated and detected (predictive detection) based on the steering angle δ (or tire turning angle δt), the accelerator opening θt, the lateral acceleration Xg, and the longitudinal acceleration Yg read in step S1. Specifically, the tuck-in behavior is estimated and detected by a processing procedure as shown in FIG.

  First, in step S11, it is determined whether or not the tire steering angle is equal to or greater than a certain amount. That is, the tire steering angle δt (= δ / Ns) is calculated from the steering angle δ and the steering gear ratio Ns, the tire steering angle δt is compared with a predetermined threshold value δtth, and the host vehicle turns on the curve. It is determined whether or not. Here, the predetermined threshold value δtth is an experimental value or an empirical value.

In this step S11, when the steering angle δt is equal to or larger than the predetermined threshold value δtth (δt ≧ δtth), the process proceeds to step S12, and when the tire steering angle δt is less than the predetermined threshold value δtth (δt <δtth), The process of FIG. 3 (step S3) is terminated.
In step S12, it is determined whether the lateral acceleration is equal to or greater than a certain amount. That is, the lateral acceleration Xg is compared with a predetermined threshold value Xgth. If the lateral acceleration Xg is equal to or greater than the predetermined threshold value Xgth (Xg ≧ Xgth), the process proceeds to step S13, where the lateral acceleration Xg is equal to the predetermined threshold value. If it is less than Xgth (Xg <Xgth), the processing shown in FIG. Here, the predetermined threshold value Xgth is an experimental value or an empirical value.

  In step S13, it is determined whether or not the amount of change in the accelerator opening (the amount of change in the accelerator return direction (change rate)) is greater than or equal to a certain amount. That is, the change amount Δθt per unit time of the accelerator opening θt is compared with a predetermined threshold value Δθtth, and when the accelerator opening change amount Δθt is equal to or larger than the predetermined threshold value Δθtth (Δθt ≧ Δθtth), step S14. When the accelerator opening change amount Δθt is less than the predetermined threshold value Δθtth (Δθt <Δθtth), the processing shown in FIG. 3 is terminated. Here, the predetermined threshold value Δθtth is an experimental value or an empirical value.

  In step S14, it is determined whether or not the amount of change (rate of change) in the longitudinal acceleration (deceleration) is greater than or equal to a certain amount. That is, the amount of change ΔYg per unit time of the longitudinal acceleration Yg is compared with a predetermined threshold value ΔYgth. If the longitudinal acceleration change amount ΔYg is equal to or larger than the predetermined threshold value ΔYgth (ΔYg ≧ ΔYgth), the process proceeds to step S15. When the longitudinal acceleration Yg is less than the predetermined threshold Ygth (ΔYg <ΔYgth), the processing shown in FIG. Here, the predetermined threshold value ΔYgth is an experimental value or an empirical value.

  As a result, the steering angle δt is greater than or equal to the predetermined threshold value δtth (δt ≧ δtth) and the lateral acceleration Xg is greater than or equal to the predetermined threshold value Xgth (Xg ≧ Xgth). In addition to detecting that the host vehicle is turning on a curve, the accelerator opening change amount Δθt is greater than or equal to a predetermined threshold value Δθtth (Δθt ≧ Δθtth) and the longitudinal acceleration change is detected in steps S13 and S14. When the amount ΔYg is equal to or greater than a predetermined threshold value ΔYgth (ΔYg ≧ ΔYgth), when it is detected that the deceleration of the host vehicle greatly varies due to the driver's accelerator operation (accelerator return operation), Is predicted to occur.

In this case, in step S15, the tack-in flag Ftg is turned on (Ftg = ON) on the assumption that the tack-in behavior is likely to occur. Then, the process shown in FIG. 3 ends.
Thus, in step S3, the vehicle behavior change is determined.
Subsequently, in step S4, the estimated yaw rate and yaw angle associated with the tuck-in behavior are calculated.

First, the estimated yaw rate φ _d ′ is calculated by the following equation (2).
φ _d ′ = (1− (m / (2 · l ² )) · ((l _f · CF _f −l _r · CF _r ) / (CF _f · CF _r )) · V ² ) ⁻¹ · V · δ / l (2)
Here, m is the mass of the vehicle, l _f , l _r is the distance between the center of gravity of the vehicle and the front and rear axles, l is the wheelbase, and CF _f , CF _r are the cornering of the front and rear wheels Power.

Based on the estimated yaw rate φ _d ′ calculated by the equation (2) and the departure determination time T _tt at the time of tuck-in, the estimated yaw angle φ _d is calculated by the following equation (3).
φ _d = φ _d ′ · T _tt (3)
Here, the departure determination time _Ttt is a predetermined time. For example, the time until the driver can determine that the vehicle has deviated due to the tuck-in behavior, for example, 1 second. The departure judgment time _Ttt is an experimental value or an empirical value.

As described above, the estimated yaw angle φ _d calculated by the equation (3) is the yaw angle of the host vehicle that is predicted to occur when there is a tuck-in behavior.
Note that, only when the tuck-in flag Ftg is ON, calculation of an estimated yaw rate or the like accompanying this tuck-in estimation may be performed.
Subsequently, in step S5, a lane departure tendency is determined. The procedure of this determination process is specifically as shown in FIG. FIG. 5 illustrates the definition of values used in this process.

First, in step S21, an estimated lateral displacement Xs of the vehicle center-of-gravity lateral position after a predetermined time T is calculated according to the state of the tack-in flag Ftg. Specifically, when the tack-in flag Ftg is OFF (Ftg = OFF), the yaw angle (actual yaw angle) φ obtained in step S1, the traveling lane curvature β, the current lateral displacement X0, and the step S2 The estimated lateral displacement Xs is calculated by the following equation (4) using the vehicle speed V obtained in the above.
Xs = Tt · V · (φ + Tt · V · β) + X0 (4)
Here, Tt is the vehicle head time for calculating the forward gaze distance, and when this vehicle head time Tt is multiplied by the own vehicle speed V, it becomes the front gaze distance. That is, the estimated lateral displacement from the center of the traveling lane after the vehicle head time Tt becomes the estimated lateral displacement Xs in the future.

On the other hand, if the tuck-in flag Ftg is ON (Ftg = ON), the yaw angle obtained in step S1 instead of the (actual yaw angle) phi, by using the estimated yaw angle phi _d calculated in the step S4, the following ( 5) Calculate the estimated lateral displacement Xs by the equation.
Xs = Tt · V · (φ _d + Tt · V · β) + X0 (5)
According to this equation (4) and (5), the estimated lateral displacement Xs, for example yaw angle phi, when focusing on phi _d, the yaw angle phi, phi _d increases, increases.

Subsequently, in step S22, departure determination is performed. Specifically, comparing the estimated lateral displacement Xs with a predetermined departure-tendency threshold value X _L.
Here, departure-tendency threshold value X _L is generally the vehicle is a value that can be grasped to be in the lane departure tendency is obtained in experiments or the like. For example, the departure tendency determination threshold value _XL is a value indicating the position of the boundary line of the travel path, and is calculated by the following equation (6).
X _L = (L−H) / 2 (6)
Here, L is the lane width, and H is the width of the vehicle. The lane width L is obtained by the imaging unit 13 processing the captured image. Further, the vehicle position may be obtained from the navigation device 14 or the lane width L may be obtained from the map data of the navigation device 14. In this departure tendency determination threshold value _XL , a positive value indicates the right side of the travel path, and a negative value indicates the left side of the travel path.

In this step S22, when the estimated lateral displacement Xs is greater than or equal to the threshold X _L for determining the tendency to deviate (| Xs | ≧ X _L), determines that there is a lane departure tendency, the estimated lateral displacement Xs is for judging the departure tendency threshold If it is less than the value _{X L (| Xs | <X} L), determines that there is no lane departure tendency.
Subsequently, in step S23, a departure determination flag Fout is set. That is, when it is determined in step S22 that there is a lane departure tendency (| Xs | ≧ X _L ), the departure determination flag Fout is turned ON (Fout = ON). Further, in step S42, when it is determined that no lane departure tendency _{(| Xs | <X L)} , turns OFF the departure flag Fout (Fout = OFF).

By the process of step S22 and step S23, for example, the vehicle is going away from the center of the lane, when the estimated lateral displacement Xs is equal to or greater than the departure-tendency threshold value _{X L (| Xs | ≧ X} L), departure The determination flag Fout is turned on (Fout = ON). Further, the vehicle (host vehicle Fout = ON state) is gradually restored to the lane center side, when the estimated lateral displacement Xs becomes less than departure-tendency threshold value _{X L (| Xs | <X} L ), The departure determination flag Fout is turned off (Fout = OFF). For example, when there is a tendency to deviate from the lane, the departure determination flag Fout is changed from ON to OFF if braking control for avoiding departure described later is performed or the driver himself performs an avoidance operation.

Subsequently, in step S24, the departure direction Dout is determined based on the lateral displacement X. Specifically, when the vehicle is laterally displaced from the center of the lane to the left, the direction is set as the departure direction Dout (Dout = left), and when the vehicle is laterally displaced from the center of the lane to the right, the direction is changed to the departure direction Dout. (Dout = right).
As described above, the lane departure tendency is determined in step S5.
Subsequently, in step S6, a yaw moment Ms to be applied to the vehicle as lane departure avoidance control is calculated.

Specifically, the target yaw moment Ms is calculated by the following equation (7) based on the estimated lateral displacement Xs obtained and lateral displacement limit distance X _L in the step S5.
Ms = K1 · K2 · (| Xs | −X _L ) (7)
Here, K1 is a constant determined from vehicle specifications, and K2 is a gain that varies according to the vehicle speed V. FIG. 6 shows an example of the gain K2. As shown in FIG. 6, for example, the gain K2 becomes a small value in the low speed range, and becomes proportional to the vehicle speed V when the vehicle speed V reaches a certain value, and then becomes a constant value with a large value when reaching a certain vehicle speed V thereafter. .

This equation (7), the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _L is, target yaw moment Ms becomes larger. Therefore, as described above, the yaw angle phi, phi _d is larger, since the estimated lateral displacement Xs increases, yaw angle phi, phi _d is greater, the greater the target yaw moment Ms.
The target yaw moment Ms is calculated when the departure determination flag Fout is ON, and the target yaw moment Ms is set to 0 when the departure determination flag Fout is OFF. The target yaw moment Ms is set to a larger value as the deviation from the lane (predetermined reference position) increases.

Further, the target yaw moment Ms is set to a positive value when a counterclockwise yaw moment is applied to the vehicle, and the target yaw moment Ms is set to a negative value when a counterclockwise yaw moment is applied to the vehicle.
Subsequently, in step S7, 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.

First, when the departure determination flag Fout is OFF (Fout = OFF), that is, when the determination result that there is no lane departure tendency is obtained, as shown in the following equations (8) and (9), the target of each wheel The brake fluid pressure Psi (i = fl, fr, rl, rr) is set to the brake fluid pressure Pmf, Pmr.
Psfl = Psfr = Pmf (8)
Psrl = Psrr = Pmr (9)
Here, Pmf is the brake fluid pressure for the front wheels. Further, Pmr is the braking fluid pressure for the rear wheels, and is a value calculated based on the braking fluid pressure Pmf for the front wheels in consideration of the front-rear distribution.

At this time, the front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr are both set to zero.
On the other hand, when the departure determination flag Fout is ON (Fout = ON), that is, when a determination result that there is a lane departure tendency is obtained, first, based on the target yaw moment Ms, the front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel A target braking hydraulic pressure difference ΔPsr is calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (10) to (13).

When | Ms | <Ms0 ΔPsf = 0 (10)
ΔPsr = 2 · Kbr · Ms / T (11)
| Ms | ≧ Ms0 ΔPsf = 2 · Kbf · (Ms−Ms0) / T (12)
ΔPsr = 2 · Kbr · Ms0 / T (13)
Here, Ms0 indicates a setting threshold value. T represents a tread. This tread T is set to the same value before and after for simplicity. Kbf and Kbr are conversion coefficients for the front wheels and the rear wheels when the braking force is converted into the braking hydraulic pressure, and are determined by the brake specifications.

  Thus, the braking force applied to the wheels is distributed according to the magnitude of the target yaw moment Ms. When the target yaw moment Ms is less than the setting threshold value Ms0, 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. In addition, when the target yaw moment Ms is equal to or larger than the setting threshold value Ms0, a predetermined value is given to each target braking hydraulic pressure difference ΔPsr, ΔPsr so that a braking force difference is generated between the front, rear, left and right wheels.

Then, by using the target braking hydraulic pressure differences ΔPsf and ΔPsr calculated as described above and the deceleration target braking hydraulic pressures Pgf and Pgr, the final target braking hydraulic pressure Psi (i) of each wheel according to the following equation (14). = Fl, fr, rl, rr).
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
(14)
In this equation (14), the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated in consideration of the deceleration operation by the driver, that is, the braking hydraulic pressures Pmf, Pmr. The braking / driving force control unit 8 outputs the calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel to the brake fluid pressure controller 7 as a brake fluid pressure command value.

With the processing as described above, the following series of operations are performed.
Various data are read from each sensor or the like (step S1), and the vehicle speed V is calculated (step S2). Then, the tack-in behavior is predicted and detected based on the steering angle δ (or the tire turning angle δt), the accelerator opening θt, the lateral acceleration Xg, and the longitudinal acceleration Yg (step S3). The estimated yaw rate φ _d ′ and yaw angle φ _d are calculated (step S4).

Subsequently, the estimated lateral displacement Xs is calculated, and the lane departure tendency is determined using the calculated estimated lateral displacement Xs (step S5). Here, the estimated lateral displacement Xs is calculated according to the state of the tack-in flag Ftg, and when the tack-in flag Ftg is OFF (Ftg = OFF), the yaw angle (actual yaw angle) φ obtained in step S1 is calculated. used is calculated the estimated lateral displacement Xs, a tuck-in flag Ftg is the case of ON (Ftg = ON), and calculates the estimated lateral displacement Xs using the estimated yaw angle phi _d calculated at step S4.

If the lane departure tendency determination result indicates that the lane departure tendency exists, the departure determination flag Fout is turned ON, and the departure direction Dout is detected. If the lane departure tendency does not exist, the departure determination flag Fout Is turned off (step S5). Here, if the tuck-in flag Ftg is ON (Ftg = ON), since it calculates the estimated lateral displacement Xs used for the determination of the lane departure tendency by using the estimated yaw angle phi _d, the lane departure tendency The case where it is assumed that there is a tendency to depart from the lane in the determination process is a case where it is predicted that a tendency to deviate from the lane will occur if a tuck-in behavior occurs.

  Subsequently, a target yaw moment Ms to be applied to the vehicle as lane departure avoidance control is calculated using the estimated lateral displacement Xs used in the determination of the lane departure tendency in step S5 (step S6), and the calculated target yaw Based on the moment Ms, the front wheel target brake hydraulic pressure difference ΔPsf and the rear wheel target brake hydraulic pressure difference ΔPsr are calculated, and finally the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated. Then, the calculated target brake fluid pressure Psi (i = fl, fr, rl, rr) is output as a brake fluid pressure command value to the brake fluid pressure control unit 7 (step S7). 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.

  In such a series of operations, when the tuck-in behavior is predicted and detected based on the steering angle δ (or the tire turning angle δt), the accelerator opening θt, the lateral acceleration Xg, and the longitudinal acceleration Yg, that is, while turning on a curve When predicting and detecting the inward turning of the host vehicle caused by the deceleration operation of the host vehicle, the estimated yaw rate and the estimated yaw angle associated with the tack-in behavior are calculated (estimated), and based on the estimated value Lane departure tendency. That is, the tendency to deviate from the lane is determined from the change in the behavior of the vehicle that will occur due to the tuck-in behavior. If there is a tendency to deviate from the lane (when it is estimated that the host vehicle will show a tendency to deviate from the lane later), the yaw moment Ms corresponding to the estimated vehicle state at the time of the tendency to deviate from the lane is calculated. The calculated yaw moment Ms is applied to the host vehicle.

  As a result, after the tack-in behavior actually occurs, before it is determined that there is a tendency to deviate from the lane due to the tack-in behavior, for example, the lane deviating tendency is not actually shown, but the tuck-in behavior is not in progress. , Or immediately after the start of the tack-in behavior, or immediately before the start of the tack-in behavior, that is, earlier than the intervention timing of the normal lane departure avoidance control, corresponding to the vehicle behavior at the time of lane departure caused by the tack-in behavior (so-called estimated vehicle behavior) By giving the subject yaw moment to the host vehicle, it is prevented from deviating from the traveling lane due to the tack-in behavior.

  That is, as shown in FIG. 7 (a) to FIG. 7 (b) (the own vehicle 100 in dotted line), at the timing when the host vehicle will show a tendency to depart from the lane due to the tack-in behavior, A yaw moment Ms that takes into account the generated turning motion of the host vehicle is applied to the host vehicle 100 (the host vehicle 100 shown by a solid line in FIG. 7) to prevent the vehicle from deviating from the traveling lane due to tack-in behavior. .

And by preventing the departure from the driving lane due to the tack-in behavior in this way, the yaw moment for avoiding lane departure does not become a large value, so the vehicle behavior when avoiding lane departure makes the driver feel uncomfortable. There is no giving.
Further, the tuck-in behavior is easily detected and predicted, for example, the tuck-in behavior is predicted and detected based on the amount of change in the accelerator opening when the driver operates the accelerator.

In addition, if a tuck-in behavior occurs, a large yaw moment will act on the host vehicle, so it is effective to detect the tuck-in behavior in advance and perform lane departure avoidance control in consideration of the yaw moment generated by the tuck-in behavior. Is that there is.
The embodiments of the present invention have been described above. However, the present invention is not limited to being realized as the embodiment.

  That is, in the above-described embodiment, the case where the tuck-in behavior occurs due to the accelerator being off has been described as the cause of the vehicle turning inside the turn while traveling on a curve (see step S3). However, it is not limited to this. For example, a tuck-in behavior may occur due to sudden braking caused by a driver's braking operation. In addition, the cause of the vehicle turning inside the turn while driving on a curve may be due to the power oversteer behavior caused by the driver's accelerator operation. In this case as well, the momentum by the power oversteer behavior, for example, the yaw moment is calculated, and the lane departure avoidance control is performed in consideration of the yaw moment.

  In the case of the power oversteer behavior, it is preferable to set the conversion coefficients Kbf and Kbr in the equations (10) to (13) to optimum values. For example, conversion coefficients Kbf and Kbr are set based on the driving state of the vehicle. For example, in the case of a front wheel drive vehicle (FF vehicle), the front wheel conversion coefficient Kbf is set to a large value, while the rear wheel conversion coefficient Kbr is set to a small value. In the case of a rear wheel drive vehicle (FR vehicle), the front wheel conversion coefficient Kbf is set to a small value, while the rear wheel conversion coefficient Kbr is set to a large value. Further, in the case of a four-wheel drive vehicle, the drive wheels change according to the traveling state, so the conversion factors Kbf and Kbr are set according to the state of the drive force of the drive wheels. Thus, by setting the conversion coefficients Kbf and Kbr according to the drive system, it is possible to generate a braking force on each wheel according to the state of the wheel when the power oversteer behavior occurs.

In the embodiment, the case where the lane departure tendency is determined based on the estimated yaw angle when the tuck-in behavior is detected and detected has been described (step S5). However, it is not limited to this. For example, when the tuck-in behavior is predicted and detected, the intervention tendency of the vehicle departure avoidance control may be advanced by correcting the departure tendency determination threshold value _XL to a small value. Thereby, as an effect similar to the case where the lane departure tendency is determined based on the estimated yaw angle, it is possible to prevent the departure from the traveling lane due to the tack-in behavior.

In the above embodiment, when the tuck-in flag Ftg is ON (Ftg = ON), instead of the yaw angle (the actual yaw angle) phi obtained in step S1, an estimated yaw angle phi _d calculated in step S4 The case where the estimated lateral displacement Xs is calculated using the above-described method has been described (see the equation (5)). However, it is not limited to this. For example, even when the tuck-in flag Ftg is ON (Ftg = ON), by the yaw angle obtained in step S1 (the actual yaw angle) phi and select-high from the calculated and estimated yaw angle phi _d in step S4 The estimated lateral displacement Xs may be calculated using the selected value.

In the above embodiment, the estimated lateral displacement Xs is calculated using the yaw angle φ and the like, and the lane departure tendency is determined based on the calculated estimated lateral displacement Xs (see step S5). . However, it is not limited to this. For example, the lane departure tendency is determined based on the change amount of the yaw rate φ ′ and the lateral displacement X. That is, for example, let dx be the amount of change in lateral displacement X (the amount of change per unit time), and using the current lateral displacement X0 of the vehicle, the estimated lateral displacement Xs is calculated by the following equation (15), and the calculated estimated lateral displacement is calculated. A lane departure tendency is determined based on the displacement Xs.
Xs = dx × T + X0 (15)

Further, the target yaw moment Ms may be calculated according to the steering torque. For example, the final target yaw moment Ms is calculated by the following equation (16) using τ as steering steering torque and Kτ as a coefficient according to the steering torque.
Ms = K _τ · τ · Ms (16)
Thus, the reason for calculating the target yaw moment Ms based on the steering steering torque τ is that the vehicle behavior by the lane departure avoidance control is influenced by the steering depending on the steering torque of the driver. For example, when the driver's steering torque is large, that is, when the steering is strongly operated, and when the driver's steering torque is small, that is, when the steering is operated while being held lightly, lane departure avoidance is avoided. The vehicle behavior changes when the yaw moment is applied.

  In the above embodiment, the yaw moment is given to the vehicle by giving a braking force difference between the left and right wheels. However, the present invention is not limited to this, for example, a steering actuator for driving the steering is provided, and this steering actuator Alternatively, the yaw moment may be applied to the host vehicle by applying a driving force to the vehicle. Moreover, the structure which gives a yaw moment to the own vehicle by combining steering and braking may be sufficient. Furthermore, the configuration may be such that the yaw moment is given to the host vehicle by changing the driving force distribution to the left and right wheels to give the driving force difference instead of the braking force difference between the left and right wheels.

  In the description of the embodiment, the process of step S5 (FIG. 4) of the braking / driving force control unit 8 realizes a lane departure tendency determining means for determining a departure tendency of the host vehicle with respect to the traveling lane, The processing of step S6 and step S7 of the braking / driving force control unit 8 realizes a yaw moment applying means for applying a yaw moment for avoiding the own vehicle to deviate from the traveling lane to the own vehicle.

  Further, the processing of step S11 and step S12 of the braking / driving force control unit 8 realizes a traveling state detecting means for detecting that the host vehicle is traveling on a curve, and the braking / driving force control unit 8 performs the above-described processing. The processing of step S13 and step S14 realizes a vehicle state detection means for detecting a vehicle state in which the fluctuation of the acceleration / deceleration operation of the host vehicle becomes large, and the estimated yaw rate and estimation of step S4 of the braking / driving force control unit 8 are realized. The calculation process of the yaw angle and the determination process of the lane departure tendency based on the estimated yaw angle in step S5 are performed by the running state detection means even before the lane departure tendency determination means determines that there is a departure tendency. It is detected that the vehicle is turning on a curve, and the vehicle state detecting means detects fluctuations in acceleration / deceleration operation of the own vehicle. When detecting the listening becomes vehicle condition, a yaw moment for avoiding the traffic lane of the vehicle to deviate realizes a function of yaw moment applying means for applying to the vehicle.

It is a schematic block diagram which shows embodiment of the vehicle carrying the lane departure prevention apparatus of this invention. It is a flowchart which shows the processing content of the controller which comprises the said lane departure prevention apparatus. It is a flowchart which shows the processing content of the vehicle behavior change determination of the said controller. It is a flowchart which shows the processing content of the deviation tendency determination of the said controller. It is a diagram used for explanation of the estimated lateral displacement Xs and the departure tendency determination threshold value X _L. It is a characteristic view which shows the relationship between the vehicle speed V and the gain K2. It is the figure used for description of the effect of this invention. It is the figure used for description of the relationship between the tack-in behavior and the deviation of the driving lane in the past.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control unit 8 Controller 9 Engine 12 Drive torque control unit 13 Imaging unit 14 Navigation device 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 20 Direction indication switch 22 FL to 22RR Wheel speed Sensor

Claims (7)

  When predicting and detecting the inward turning behavior of the host vehicle caused by the acceleration / deceleration operation of the host vehicle turning on a curve, and predicting and detecting the deviation tendency of the host vehicle from the driving lane due to the incision behavior A lane departure prevention apparatus, characterized in that a yaw moment for avoiding the own vehicle from deviating from the traveling lane is applied to the own vehicle.   The lane departure prevention apparatus according to claim 1, wherein the cutting behavior is predicted and detected based on a driver's brake operation or accelerator operation. A lane departure tendency determination means for determining the departure tendency of the host vehicle with respect to the traveling lane, and a yaw for avoiding the departure of the host vehicle from the traveling lane when the lane departure tendency determination means determines that there is a lane departure tendency. In a lane departure prevention device comprising a yaw moment applying means for applying a moment to the host vehicle,
Traveling state detecting means for detecting that the host vehicle is traveling around a curve,
Vehicle state detection means for detecting a vehicle state in which fluctuations in acceleration / deceleration operation of the host vehicle increase,
The yaw moment applying means detects that the traveling state detecting means detects that the host vehicle is traveling around a curve even before the lane departure tendency determining means determines that there is a departure tendency, and the vehicle When the state detection means detects a vehicle state in which the fluctuation of the acceleration / deceleration operation of the own vehicle becomes large, a yaw moment for avoiding the departure of the own vehicle from the traveling lane is given to the own vehicle. Lane departure prevention device.   The vehicle state detecting means detects a brake operation by a driver that decelerates the host vehicle as the vehicle state, and the yaw moment applying means is caused by fluctuations in the deceleration operation of the host vehicle due to the brake operation. 4. The lane departure prevention apparatus according to claim 3, wherein a yaw moment is applied to the own vehicle in consideration of the generated inward turning behavior of the own vehicle.   The vehicle state detection means detects an accelerator operation by a driver that accelerates / decelerates the host vehicle as the vehicle state, and the vehicle state detection means generates a change in the acceleration / deceleration operation of the host vehicle caused by the accelerator operation. 4. A lane departure prevention apparatus according to claim 3, wherein a yaw moment that takes into account the inward turning behavior is applied to the host vehicle.   The yaw moment applying means predicts whether or not there is a tendency to deviate from the traveling lane during the curve turning due to a change in acceleration / deceleration operation of the own vehicle detected by the vehicle state detecting means, and a deviation tendency is predicted A lane departure prevention device according to any one of claims 3 to 5, wherein a yaw moment is applied to the vehicle.   The lane departure tendency determination means sets a determination threshold for determining the departure tendency earlier when the vehicle state detection means detects a vehicle state in which the fluctuation of acceleration / deceleration operation of the host vehicle is large. The lane departure prevention device according to any one of claims 3 to 6, wherein the lane departure prevention device is changed to a direction in which it is determined that there is a vehicle.

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