JP4735147B2 - 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.

For example, as in the technique disclosed in Patent Document 1, when a lane marking (lane marker) cannot be recognized, or when the control operation switch is turned on, the lane departure has already occurred. When the vehicle is in the state, there are some that restrict the departure prevention control by prohibiting the start of the lane departure prevention control. Thereby, it is possible to prevent the departure prevention control from being performed with a large control amount, and to reduce the uncomfortable feeling given to the driver.
JP 2003-154910 A

In the conventional example, in an unstable scene in which the recognition state and the non-recognition state of the lane line are repeated, the lane departure prevention control can be prevented from malfunctioning by limiting the lane departure prevention control. However, in a traveling lane with repair marks remaining on the lane markings, the repair marks may be misrecognized as recognition targets, and malfunction of the lane departure prevention control cannot be prevented, giving the driver a sense of discomfort. There is. In such a case, if the lane departure prevention control is activated for the repair mark, it may be impossible to prevent the lane departure at a necessary timing with respect to the original lane marking.
The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a lane departure prevention device that can prevent the lane departure prevention control from being operated on a repair mark.

The lane departure prevention device according to claim 1 detects the detection state of the lane line by the lane line detection unit, and when the detection state of the lane line detected by the lane detection state detection unit is in a predetermined state, If it is determined that the lane marking is changing suddenly and it is determined that it is changing suddenly, the control by the departure avoidance control means is suppressed.
At this time, the lane detection state detection means detects the detection state of the left and right lane markings that make up the traveling lane, and the lane sudden change determination means determines whether one lane marking line has suddenly changed or not. This is based on the detection status of the marking line .

  According to the lane departure prevention apparatus according to claim 1, when the lane division line is suddenly changed, the lane departure prevention control is suppressed, and therefore, the lane division line having a high possibility of repair marks is changed suddenly. Therefore, the lane departure prevention control is prevented from malfunctioning with respect to repair marks or the like by suppressing the lane departure prevention control.

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.
1st Embodiment is a rear-wheel drive vehicle carrying the lane departure prevention apparatus based on this 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 first 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 marking (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 marking. Here, the traveling lane is a lane for the host vehicle to travel specified by lane markings that normally exist on the left and right sides of the road.
Furthermore, 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 with respect to the travel lane, a travel lane curvature β, and the like. Is calculated. Regarding the lateral displacement X, specifically, the lateral displacement (hereinafter referred to as the left lateral displacement) XL from the left lane line (hereinafter referred to as the left lane) and the right lane line (hereinafter referred to as the right lane). XR) (hereinafter referred to as right lateral displacement) XR. The imaging unit 13 sets the left lane detection flag FsL to ON when the left lane is detected, and sets the right lane detection flag FsR to ON when the right lane is detected.

The imaging unit 13 outputs the calculated yaw angle φ, lateral displacement X (XL, XR), lane detection flags FsL, FsR, travel lane curvature β, and the like to the braking / driving force control unit 8.
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.
The vehicle is also provided with a radar 16 for measuring the distance between the host vehicle and the front obstacle by sweeping laser light forward and receiving the reflected light from the preceding obstacle. ing.
The radar 16 then outputs information on the position of the front obstacle to the braking / driving force control unit 8. The detection result by the radar 16 is used for processing in an ACC, a rear-end collision speed reducing brake device, or the like.

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

  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 Pm and direction switch signal, drive torque Tw from the drive torque control unit 12, yaw angle φ from the imaging unit 13, lateral displacement XL to the left lane, lateral displacement XR to the right lane, lane detection flags FsL and FsR, and travel Read lane curvature β.

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 the 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, an estimated lateral displacement (estimated deviation value) is calculated. Specifically, using the yaw angle φ, the travel lane curvature β and the lateral displacements XL and XR obtained in step S1 and the vehicle speed V obtained in step S2, the left side is estimated by the following equation (2). A lateral displacement (hereinafter referred to as a left-side estimated lateral displacement) XsL is calculated, and an estimated lateral displacement (hereinafter referred to as a right-side estimated lateral displacement) XsR for the right side is calculated by the following equation (3).
XsL = Tt · V · (φ + Tt · V · β) + XL (2)
XsR = Tt · V · (φ + Tt · V · β) + XR (3)

  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 values from the respective lanes (left lane and right lane) after the vehicle heading time Tt become the estimated lateral displacements XsL and XsR in the future. According to the equations (2) and (3), the estimated lateral displacements XsL and XsR increase as the yaw angle φ increases, for example, when attention is paid to the yaw angle φ. Further, as shown in FIGS. 3A to 3C, the estimated lateral displacements XsL and XsR are positive when they are on the right side of each lane, and are negative when they are on the left side of each lane. Value.

Subsequently, in step S4, departure tendency determination is performed. Specifically, the estimated lateral displacements XsL and XsR are compared with a predetermined departure tendency determination threshold value Xc.
Here, the threshold value Xc for determining the departure tendency is a value that can be generally grasped that the vehicle has a tendency to depart from the lane, and is obtained through an experiment or the like. As shown in FIG. 4, the departure tendency determination threshold value Xc becomes a positive value when set in the traveling lane inner side direction and becomes a negative value when set in the driving lane outer side direction. This departure tendency determination threshold value Xc is set on each lane (Xc = 0), but a reference point may be set on the positive value side with respect to each lane in order to allow some margin. .

  When the left lane detection flag FsL obtained in step S1 is ON and the left estimated lateral displacement XsL is equal to or less than the departure tendency determination threshold value Xc (FsL = ON and XsL ≦ Xc), the host vehicle is in the traveling lane. It is determined that the vehicle has a tendency to deviate from the (left lane) (the left lateral estimated lateral displacement XsL is left from the left lane by the deviating tendency determination threshold value Xc), and the departure determination flag Fld is set to LEFT (Fld = LEFT). Further, when the right lane detection flag FsR obtained in step S1 is ON and the right estimated lateral displacement XsR is equal to or greater than the departure tendency determination threshold value −Xc (positive value Xc) (FsR = ON and XsR ≧ − Xc), it is determined that the host vehicle has a tendency to deviate from the driving lane (right lane) (the estimated right side lateral displacement XsR is deviated from the right lane by the threshold value Xc for deviating tendency), and a deviation determination flag Set Fld to RIGHT (Fld = RIGHT). In other cases, the departure determination flag Fld is set to OFF (Fld = OFF).

Subsequently, in step S5, a sudden change determination of each lane (left lane, right lane) is performed. Specifically, the sudden change determination of each lane is performed based on the change amount and the change direction of each lateral displacement XL, XR. That is, as follows.
(1) Sudden change determination of left lane (1-1) Difference (absolute value) between left lateral displacement XL (n) obtained this time and left lateral displacement XL (n-1) obtained last time is a predetermined threshold value. When Xh or more and the value obtained by subtracting the left lateral displacement XL (n−1) obtained previously from the left lateral displacement XL (n) obtained this time is less than 0 (negative value) (| XL (n) − XL (n−1) | ≧ Xh and XL (n) −XL (n−1) <0), the left lane is in the right direction (inside the driving lane, the direction in which the lane departure tendency increases or the lane departure amount increases) It is determined that the left sudden change flag FcL is set to ON (FcL = ON).

The difference (| XL (n) −XL (n−1) |) indicates an abrupt variable, and whether or not the subtraction value (XL (n) −XL (n−1)) is less than 0 (negative value). Is a sudden change direction determination, and if the subtraction value (XL (n) -XL (n-1)) is less than 0, the left lane changes to the right (inside the driving lane). It shows that.
Further, the predetermined threshold value Xh is a threshold value for determining whether or not each lane is suddenly changed, that is, for comparing with a change amount of the lane (lateral change amount) with respect to the own vehicle. Value.
(1-2) Otherwise, the left sudden change flag FcL is set to OFF (FcL = OFF).

(2) Determination of sudden change in right lane (2-1) Difference (absolute value) between right lateral displacement XR (n) obtained this time and right lateral displacement XR (n-1) obtained last time is a predetermined threshold value When Xh is equal to or greater than Xh and the value obtained by subtracting the right lateral displacement XR (n−1) obtained previously from the right lateral displacement XR (n) obtained this time is greater than 0 (positive value) (| XR (n) − XR (n−1) | ≧ Xh and XR (n) −XR (n−1)> 0), the right lane is in the left direction (inside the driving lane, the direction in which the lane departure tendency increases or the lane departure amount increases) The right lane sudden change flag FcL is set to ON (FcR = ON).

The difference (| XR (n) −XR (n−1) |) indicates an abrupt variable, and whether or not the subtraction value (XR (n) −XR (n−1)) is greater than 0 ( The determination of whether or not it is a positive value is a determination of a sudden change direction. If the subtraction value (XR (n) −XR (n−1)) is greater than 0, the right lane is in the left direction (inside the driving lane). Indicates that it has changed.
(2-2) In other cases, the right lane sudden change flag FcR is set to OFF (FcR = OFF).

Further, as shown in the following equation (4), based on the yaw angle φ, a predetermined threshold value Xh is set from a lateral displacement that can change during a predetermined time ΔTs (sampling cycle in which the control program is repeatedly executed). You may do it.
Xh = Lc · φ · ΔTs
= (Tt · V) · φ · ΔTs (4)
Here, Lc is a front position (front gaze point distance) for determining a sudden change in the lane. This Lc may be a fixed value or may vary according to the vehicle speed V as given by Tt · V. As shown in the equation (4), the predetermined threshold value Xh is set based on at least one of the yaw angle φ and the host vehicle speed V.

The determination of the sudden change of the lane may be performed based on the sudden change speed (change speed) in the lateral direction of the lane. For example, when the sudden change speed of the lane is equal to or higher than a predetermined threshold value to be compared with the sudden change speed, it is determined that the lane is changing suddenly.
Subsequently, in step S6, permission or prohibition of lane departure prevention control is determined. FIG. 5 shows the procedure of the determination process. In the process shown in FIG. 5, when it is determined in step S5 that the lane has suddenly changed, the lane departure prevention control in the direction determined to be sudden change is prohibited for a predetermined time, and then the lane departure state disappears (lane departure tendency). After that, the lane departure prevention control is permitted again. In the process shown in FIG. 5, first, various processes are performed on the left lane (steps S21 to S27), and then various processes are performed on the right lane (steps S28 to S34).

That is, as processing for the left lane, in step S21, it is determined whether or not it is determined in step S5 that the left lane has suddenly changed. If it is determined that the left lane has suddenly changed (FcL = ON), the process proceeds to step S22. If it is not determined that the left lane has suddenly changed (FcL = OFF), the process proceeds to step S24.
In step S22, an elapsed time counter CnL for prohibiting departure prevention control for deviation from the left lane is set to a predetermined value Cs, and in step S23, a left control prohibition flag FnL is set to ON (FnL = ON). . Then, the process proceeds to step S28. The predetermined value Cs is the minimum time during which lane departure prevention control is prohibited.

In step S24, it is determined whether or not the elapsed time counter CnL is zero. That is, it is determined whether or not a predetermined time (Cs) has elapsed since the departure prevention control for the departure from the left lane is prohibited. If the predetermined time has not elapsed (CnL ≠ 0), the process proceeds to step S25. If the predetermined time has elapsed (CnL = 0), the process proceeds to step S26.
In step S25, the elapsed time counter CnL is updated (decremented) (CnL = CnL-1). Then, the process proceeds to step S28. At this time, the left side control prohibition flag FnL is not updated (FnL = ON).

  In step S26, based on the determination result of the lane departure tendency in step S4, it is determined whether or not there is a departure tendency (lane departure tendency to the left side) with respect to the left lane. If there is a departure tendency with respect to the left lane (Fld = LEFT), the process proceeds to step S28. At this time, the left side control prohibition flag FnL is not updated (FnL = ON). On the other hand, if there is no tendency to deviate from the left lane (Fld ≠ LEFT), the process proceeds to step S27.

In step S27, the left control prohibit flag FnL is cleared (FnL = OFF). Then, the process proceeds to step S28.
As described above, in Steps S21 to S27, various processes are performed for the left lane. Similarly, in steps S28 to S30, various processes are performed for the right lane.

That is, first, in step S28, it is determined whether or not it is determined in step S5 that the right lane has suddenly changed. If it is determined that the right lane has suddenly changed (FcR = ON), the process proceeds to step S29. If it is not determined that the right lane has suddenly changed (FcR = OFF), the process proceeds to step S31.
In step S29, an elapsed time counter CnR for prohibiting the departure prevention control for deviation from the right lane is set to a predetermined value Cs, and in the subsequent step S30, the right control inhibition flag FnR is set to ON (FnR = ON). . Then, the process shown in FIG. 5 ends (the process from step S21 is performed again).

In step S31, it is determined whether or not the elapsed time counter CnR is zero. That is, it is determined whether or not a predetermined time (Cs) has elapsed since the departure prevention control for the departure from the right lane is prohibited. If the predetermined time has not elapsed (CnR ≠ 0), the process proceeds to step S32. If the predetermined time has elapsed (CnR = 0), the process proceeds to step S33.
In step S32, the elapsed time counter CnR is updated (decremented) (CnR = CnR-1). Then, the process shown in FIG. 5 ends (the process from step S21 is performed again). At this time, the right control prohibition flag FnR is not updated (FnR = ON).

In step S33, based on the determination result of the lane departure tendency in step S4, it is determined whether or not there is a departure tendency (lane departure tendency to the right side) with respect to the right lane. Here, when there is a tendency to deviate from the right lane (Fld = RIGHT), the processing shown in FIG. 5 ends (the processing from step S21 is performed again). At this time, the right control prohibition flag FnR is not updated (FnR = ON). On the other hand, when there is no tendency to deviate from the right lane (Fld ≠ RIGHT), the process proceeds to step S34.
In step S34, the right control inhibition flag FnR is cleared (FnR = OFF). Then, the process shown in FIG. 5 ends (the process from step S21 is performed again).

  As a result of the above processing, when the left lane changes suddenly (FcL = ON), the elapsed time counter CnL is set to a predetermined value Cs (CnL = Cs), and the left control prohibit flag FnL is turned ON. Set (FnL = ON) (steps S21 to S23). When the left lane is not in a sudden change state (FcL = OFF), the elapsed time counter CnL is updated (decremented) from the predetermined value Cs (step S24, step S25), and the elapsed time counter CnL becomes 0. (CnL = 0) If the left lane is not in the departure state, the left control prohibit flag FnL is set to OFF (FnL = OFF). On the other hand, if the left lane is in the departure state, the left control prohibit flag When FnL is maintained ON (FnL = ON) and the left lane is no longer in the departure state, the left control prohibit flag FnL is set OFF (FnL = OFF) (steps S24 to S27).

  In the same way as the processing for the right lane, when the right lane changes suddenly (FcR = ON), the elapsed time counter CnR is set to a predetermined value Cs (CnR = Cs), and the right control prohibition flag FnR is set. Set to ON (FnR = ON) (steps S28 to S30). Then, when the right lane is not suddenly changed (FcR = OFF), the elapsed time counter CnR is updated (decremented) from the predetermined value Cs (steps S31 and S32), and the elapsed time counter CnR becomes 0. (CnR = 0) If the right lane is not a departure state, the right control prohibition flag FnR is set to OFF (FnR = OFF). On the other hand, if the right lane is a departure state, the right control inhibition flag FnR is kept ON (FnR = ON), and when the right lane is no longer in the departure state, the right control prohibition flag FnR is set to OFF (FnR = OFF) (steps S31 to S34).

When the lane has not changed suddenly from the beginning, the control prohibition flags FnL and FnR are set to OFF. That is, the lane departure prevention control can be operated as usual.
Subsequently, in step S7, based on the determination result of the lane departure tendency in step S4 and the determination result of permission and prohibition of the lane departure prevention control in step S6, the target yaw moment Ms to be given to the host vehicle as the lane departure prevention control. Is calculated. Specifically, it is as follows.

(1) For the left lane, when Fld = LEFT and FnL = OFF (Equation (5))
Ms = Kv1 · Ks · (XcL−Xc) (Ms: negative value) (5)
(2) For the right lane, when Fld = RIGHT and FnR = OFF (Equation (6))
Ms = Kv1 · Ks · (XcR + Xc) (Ms: positive value) (6)
(3) Otherwise, the target yaw moment Ms is set to 0 (Ms = 0)
Here, Kv1 is a constant determined by vehicle specifications, and Ks is a gain that varies according to the host vehicle speed.

According to the equations (5) and (6), the target yaw moment Ms increases as the difference between the estimated lateral displacements XsL, XsR and the departure tendency determination threshold value Xc increases, that is, as the lane departure tendency increases. Become.
Subsequently, in step S8, a target brake hydraulic pressure for each wheel is calculated. That is, the final braking fluid pressure is calculated based on the presence or absence of braking control for preventing lane departure. Specifically, it is calculated as follows.

When the departure determination flag Fld is OFF (Fld = OFF), that is, when the determination result that there is no lane departure tendency is obtained, as shown in the following equations (7) and (8), the target braking fluid for each wheel The pressure Psi (i = fl, fr, rl, rr) is set to the brake fluid pressure Pmf, Pmr.
Psfl = Psfr = Pmf (7)
Psrl = Psrr = Pmr (8)
Here, Pmf is the brake fluid pressure for the front wheels. Further, Pmr is the braking fluid pressure for the rear wheels, and is a value calculated based on the braking fluid pressure Pmf for the front wheels in consideration of the front-rear distribution. For example, if the driver is operating a brake, the brake fluid pressures Pmf and Pmr are values corresponding to the amount of brake operation (master cylinder fluid pressure Pm).

On the other hand, when the target yaw moment Ms is calculated in step S7 (Fld = LEFT and FnL = OFF or Fld = RIGHT and FnR = OFF), that is, when the determination result that there is a lane departure tendency is obtained, Based on the calculated target yaw moment Ms, a front wheel target braking hydraulic pressure difference ΔPsf and a rear wheel target braking hydraulic pressure difference ΔPsr are calculated. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (9) to (12).
When | Ms | <Ms1, ΔPsf = 0 (9)
ΔPsr = 2 · Kbr · | Ms | / T (10)
When | Ms | ≧ Ms1 ΔPsf = 2 · Kbf · (| Ms | −Ms1) / T (11)
ΔPsr = 2 · Kbr · Ms1 / T (12)
Here, Ms1 represents a setting threshold value. T represents a tread. This tread T is set to the same value before and after for simplicity. Kbf and Kbr are conversion coefficients for the front wheels and the rear wheels when the braking force is converted into the braking hydraulic pressure, and are determined by the brake specifications.

  Thus, the braking force generated by the wheels is distributed according to the magnitude of the target yaw moment Ms. When the target yaw moment Ms is less than the setting threshold value Ms1, the front wheel target braking fluid pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking fluid pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. In addition, when the target yaw moment Ms is equal to or greater than the setting threshold value Ms1, a predetermined value is given to each target brake hydraulic pressure difference ΔPsr, ΔPsr, and a braking force difference is generated between the left and right wheels respectively.

Then, based on the deviation determination flag Fld, the final target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated using the calculated target braking fluid pressure differences ΔPsf, ΔPsr. That is, when the departure determination flag Fld is LEFT (Fld = LEFT), that is, when there is a lane departure tendency with respect to the left lane, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (13)

When the departure determination flag Fld is RIGHT (Fld = RIGHT), that is, when there is a lane departure tendency with respect to the right lane, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pmf + ΔPsf
Psfr = Pmf
Psrl = Pmr + ΔPsr
Psrr = Pmr
... (13)
According to the equations (13) and (14), the braking force difference between the left and right wheels is generated so that the braking force of the wheel on the lane departure avoidance side is increased.

  Further, as shown in the equations (13) and (14), the brake operation by the driver, that is, the target brake fluid pressure Psi (i = fl, fr, rl) of each wheel in consideration of the brake fluid pressures Pmf, Pmr. , Rr). Then, the braking / driving force control unit 8 uses the target braking hydraulic pressure Psi (i = fl, fr, rl, rr) calculated for each wheel thus calculated as a braking fluid pressure command value to the braking fluid pressure control unit 7. Output.

The outline of the above series of processing is as follows.
First, various data are read (step S1), and the vehicle speed V is calculated (step S2). Subsequently, a future estimated lateral displacement (estimated deviation value) Xs is calculated (step S3), and the calculated estimated lateral displacement Xs is compared with the departure tendency determination threshold value Xc to determine the departure tendency. (Step S4). Here, when it is determined that the vehicle has a departure tendency with respect to the left lane, the departure determination flag Fld is set to LEFT (Fld = LEFT), and when it is determined that there is a departure tendency with respect to the right lane, the departure determination flag Fld. Is set to RIGHT (Fld = RIGHT). In other cases, the departure determination flag Fld is set to OFF (Fld = OFF).

  Subsequently, the sudden change determination of each lane is performed based on the change amount and the change direction of each lateral displacement XL, XR (step S5). If the left lane suddenly changes to the right (inside the lane), the left lane sudden change flag FcL is set to ON (FcL = ON), and the right lane suddenly changes to the left (inside the lane). If so, the right lane sudden change flag FcR is set to ON (FcR = ON). In other cases, the sudden change flags FcL and FcR are set to OFF (FcL = OFF, FcR = OFF).

  Subsequently, the permission or prohibition of the lane departure prevention control is determined based on the state of the sudden change flags FcL and FcR (step S6). Here, the control prohibition flags FnL and FnR are set according to the conditions. The target yaw moment Ms is calculated based on the state of the control prohibition flags FnL and FnR and the state of the departure determination flag Fld (step S7), and the target of each wheel is calculated based on the calculated target yaw moment Ms. A brake fluid pressure is calculated (step S8).

  Thus, when the control prohibition flags FnL and FnR are OFF, if the host vehicle tends to depart from the lane (Fld = LEFT or FId = RIGHT), the yaw moment is applied to the host vehicle, and the host vehicle is in the lane. Deviation is prevented. On the other hand, when the control prohibition flags FnL and FnR are ON, if it is determined that the host vehicle is in a lane departure tendency in the direction in which the control prohibition flags FcL and FcR are ON, the lane departure prevention control is performed. It will not work.

Next, effects of the first embodiment will be described.
As described above, when the lane (lane division line) changes suddenly, the control prohibition flags FnL and FnR are turned ON to prohibit the lane departure prevention control. The repair mark remaining in the driving lane does not correctly indicate the driving lane that the host vehicle should travel, but is a direction that deviates greatly from the direction indicated by the official lane, so a sudden change in the lane (lane marking) was detected. In this case, it is possible to prevent the lane departure prevention control from malfunctioning on the basis of the repair trace remaining in the traveling lane by prohibiting the lane departure prevention control, assuming that the lane is a repair trace remaining in the traveling lane. In this way, even if the lane departure tendency is shown based on the official lane near the repair mark remaining in the driving lane, the lane departure prevention control is activated at the necessary timing for the official lane. To come. That is, it is possible to achieve both the prevention of malfunction of the lane departure prevention control for the repair marks remaining in the traveling lane and the prevention of the malfunction of the lane departure prevention control for the official lane.

  Further, as described above, the predetermined threshold value Xh is set based on at least one of the yaw angle φ and the host vehicle speed V. This makes it possible to reliably determine a sudden change in a lane (lane division line), while erroneously determining that it is a sudden change when the lane (lane division line) is not actually changing suddenly. The predetermined threshold value Xh is appropriately set so as not to occur. That is, the factors that can contribute to the lateral displacement that actually changes during a predetermined time include the yaw angle φ, the host vehicle speed V, and the lateral speed. Based on the yaw angle φ, the host vehicle speed V, and the lateral speed, which are these factors. Thus, the predetermined threshold value Xh is appropriately set by setting the predetermined threshold value Xh. Specifically, in a situation where the amount of lateral displacement that changes during a predetermined time is large (the yaw angle is large, the lateral speed is large, etc.), the predetermined threshold value Xh is increased, and conversely, it changes during the predetermined time. In a situation where the amount of lateral displacement to be performed is small (eg, the yaw angle is small and the lateral velocity is small), the predetermined threshold value Xh is reduced to enable more reliable determination.

Further, as described above, the sudden change of the lane (lane line) is determined using the predetermined threshold value Xh (see step S5). Thereby, it can prevent misjudging that the lane (lane division line) has changed suddenly.
In addition, as described above, when the lane (lane division line) changes to the inside of the traveling lane, the direction in which the lane departure tendency increases or the lane departure amount increases, it is determined that the lane is changing suddenly. (See step S5). Thereby, a sudden change in the lane can be detected more efficiently.

Further, as described above, after determining that the lane (lane division line) is changing suddenly, the lane departure prevention control is prohibited for a predetermined time (see step S24). That is, lane departure prevention control is prohibited for at least a certain period of time after determining that the lane (lane division line) has suddenly changed. Thereby, it can prevent more reliably that lane departure prevention control malfunctions based on the repair trace which remains in a driving lane.
Further, as described above, lane departure prevention control is prohibited as long as there is a lane departure tendency for the lane even after a lapse of a predetermined time since it is determined that the lane (lane division line) has suddenly changed ( (See step S26). Thereby, it can prevent more reliably that lane departure prevention control malfunctions based on the repair trace which remains in a driving lane.

Next, a second embodiment will be described.
This second embodiment is also a rear wheel drive vehicle equipped with the lane departure prevention apparatus according to the present invention. In the first embodiment, the determination of a sudden change in the lane is made by paying attention only to the lane. On the other hand, in 2nd Embodiment, the determination of the sudden change of one lane is performed also with reference to the detection state of the other lane.
In order to achieve this, the braking / driving force control unit 8 performs the processing shown in FIG. 2 as in the first embodiment, and the processing in step S5 shown in FIG. The processing content shown in FIG. 6 is different from that of the embodiment.

In the process shown in FIG. 6, first, various processes are performed on the left lane (steps S41 to S48), and then various processes are performed on the right lane (steps S49 to S56).
That is, as processing for the left lane, it is determined in step S41 whether the left lane has been detected. If the left lane is detected (FsL = ON), the process proceeds to step S43. If the left lane is not detected (FsL = OFF), the process proceeds to step S42.

In step S42, the left lane sudden change flag FcL is set to ON (FcL = OFF). Then, the process proceeds to step S49.
In step S43, it is determined whether a right lane has been detected. If the right lane is detected (FsR = ON), the process proceeds to step S45. If the right lane is not detected (FsR = OFF), the process proceeds to step S44.

In step S44, that is, when only the left lane is detected, the sudden change determination threshold value XhL of the left lane is set to the second threshold value Xh2. Then, the process proceeds to step S46.
In step S45, that is, when the left and right lanes are detected, the sudden change determination threshold value XhL for the left lane is set to the first threshold value Xh1. Then, the process proceeds to step S46. Here, the relationship between the first threshold value Xh1 and the second threshold value Xh2 is such that the first threshold value Xh1 is larger than the second threshold value Xh2 (Xh1> Xh2).

  In step S46 and step S47, the sudden change determination as in step S5 is performed for the left lane. That is, first, in step S46, the difference (absolute value) between the left lateral displacement XL (n) obtained this time and the left lateral displacement XL (n-1) obtained last time is the left lane set in step S44 or step S45. Whether or not it is greater than or equal to the sudden change determination threshold value XhL, that is, the sudden change amount is determined. Here, if the difference is equal to or greater than the threshold value XhL for sudden change in the left lane (| XL (n) −XL (n−1) | ≧ XhL), the process proceeds to step S47, and the difference is determined to be sudden change in the left lane. If it is less than the threshold value XhL (| XL (n) −XL (n−1) | <XhL), the process proceeds to step S42.

  In step S47, it is determined whether or not the value obtained by subtracting the left lateral displacement XL (n-1) obtained last time from the left lateral displacement XL (n) obtained this time is less than 0, that is, the sudden change direction. Here, when the subtraction value is less than 0 (XL (n) −XL (n−1) <0), that is, when the left lane changes to the right (inside the driving lane), the process proceeds to step S48. When the subtraction value is 0 or more (XL (n) −XL (n−1) ≧ 0), that is, when the left lane changes to the left (outside the driving lane), the process proceeds to step S42.

In step S48, the left lane sudden change flag FcL is set to ON (FcL = ON). Then, the process proceeds to step S49.
As described above, in steps S41 to S48, various processes are performed on the left lane. Similarly, in steps S49 to S56, various processes are performed for the right lane.

That is, first, in step S49, it is determined whether the right lane is detected. If the right lane is detected (FsR = ON), the process proceeds to step S51. If the right lane is not detected (FsR = OFF), the process proceeds to step S50.
In step S50, the right lane sudden change flag FcR is set to ON (FsR = OFF). Then, the process shown in FIG. 6 ends.

In step S51, it is determined whether the left lane is detected. If the left lane is detected (FsL = ON), the process proceeds to step S53. If the left lane is not detected (FsL = OFF), the process proceeds to step S52.
In step S52, that is, when only the right lane is detected, the sudden change determination threshold value XhR for the right lane is set to the second threshold value Xh2. Then, the process proceeds to step S54.
In step S53, that is, when the left and right lanes are detected, the sudden change determination threshold value XhL for the right lane is set to the first threshold value Xh1. Then, the process proceeds to step S54.

  In step S54 and step S55, the sudden change determination as in step S5 is performed for the right lane. That is, first, in step S54, the difference (absolute value) between the right lateral displacement XR (n) obtained this time and the left lateral displacement XR (n-1) obtained last time is the right lane set in step S52 or step S53. Whether or not it is greater than or equal to the sudden change determination threshold value XhR, that is, the sudden change amount is determined. Here, when the difference is equal to or greater than the threshold value XhR for sudden change in the right lane (| XR (n) −XR (n−1) | ≧ XhR), the process proceeds to step S55, and the difference is determined to be sudden change in the right lane. If it is less than the threshold value XhR (| XR (n) −XR (n−1) | <XhR), the process proceeds to step S50.

In step S55, it is determined whether or not the value obtained by subtracting the previously obtained right lateral displacement XR (n-1) from the right lateral displacement XR (n) obtained this time is greater than 0, that is, the sudden change direction. Here, when the subtraction value is larger than 0 (XR (n) −XR (n−1)> 0), that is, when the right lane changes to the left (inside the driving lane), the process proceeds to step S56. When the subtraction value is 0 or less (XR (n) −XR (n−1) ≦ 0), that is, when the right lane changes to the right (outside the driving lane), the process proceeds to step S50.
In step S56, the left lane sudden change flag FcR is set to ON (FcR = ON). Then, the process shown in FIG. 6 ends.

  By the above processing, as the processing related to the left lane, when the left lane is detected (FsL = ON), when the right lane is detected (FsR = ON), the threshold value XhL for sudden change determination of the left lane is set to the first lane. If the threshold value Xh1 is set (XhL = Xh1) and the right lane cannot be detected (FsR = OFF), the left lane sudden change determination threshold value XhL is set to the second threshold value Xh2 (XhL = Xh2). (Steps S41 to S45).

  Then, based on the left lane sudden change determination threshold value XhL set in this way, the left lane sudden change determination is performed in the same manner as in the first embodiment. In other words, the difference (absolute value) between the left lateral displacement XL (n) obtained this time and the left lateral displacement XL (n-1) obtained last time is equal to or greater than the threshold value XhL for sudden change determination of the left lane and obtained this time. When the value obtained by subtracting the left lateral displacement XL (n−1) obtained previously from the left lateral displacement XL (n) is less than 0 (| XL (n) −XL (n−1) | ≧ XhL and XL (n) -XL (n-1) <0), it is determined that the left lane has suddenly changed to the right (in the driving lane, the direction in which the lane departure tendency tends to increase or the lane departure amount increases), and the left sudden change flag FcL is set to ON. Set (FcL = ON) (steps S46 to S48). If the left lane cannot be detected (FsL = OFF), the left sudden change flag FcL is set to OFF (FcL = OFF, step S42).

  Similarly, the processing related to the right lane is the same as the above. When the right lane is detected (FsR = ON), when the left lane is detected (FsL = ON), the right lane sudden change determination threshold value XhR is set. When the first threshold value Xh1 is set (XhR = Xh1) and the left lane cannot be detected (FsL = OFF), the sudden change determination threshold value XhR for the right lane is set to the second threshold value Xh2 (XhR = Xh2) (steps S49 to S53).

  Then, based on the threshold value XhR for sudden change determination of the right lane set in this way, the sudden change determination of the right lane is performed in the same manner as in the first embodiment. That is, the difference (absolute value) between the right lateral displacement XR (n) obtained this time and the right lateral displacement XR (n-1) obtained last time is equal to or greater than the threshold value XhR for sudden change determination in the right lane, and obtained this time. When the value obtained by subtracting the right lateral displacement XR (n−1) obtained previously from the right lateral displacement XR (n) is larger than 0 (| XR (n) −XR (n−1) | ≧ XhR and XR (n ) -XR (n-1)> 0), it is determined that the right lane has suddenly changed to the left (inside the driving lane, the direction in which the lane departure tendency increases or the lane departure amount increases), and the right abrupt change flag FcR is turned on (FcR = ON) (steps S54 to S56). If the right lane cannot be detected (FsR = OFF), the right sudden change flag FcR is set to OFF (FcR = OFF, step S50).

  Here, paying attention to the processing related to the left lane, the second threshold value Xh2 is smaller than the first threshold value Xh1 (Xh2 <Xh1). It is easier to determine that the second threshold value Xh2 is suddenly changed in the case where the second threshold value Xh2 is set in the left lane sudden change determination threshold value XhL than in the case where the threshold value Xh1 is set. Therefore, since the case where the second threshold value Xh2 is set is a case where only the left lane is detected, when only the left lane is detected, it is determined that the left lane is suddenly changing. It becomes easy to be done.

  Similarly, in the processing related to the right lane, the second threshold value Xh2 is smaller than the first threshold value Xh1 (Xh2 <Xh1). It is easier to determine that the second threshold value Xh2 is suddenly changed in the case where the second threshold value Xh2 is set in the right lane sudden change determination threshold value XhR than in the case where the threshold value Xh1 is set. Therefore, since the case where the second threshold value Xh2 is set is a case where only the right lane is detected, when only the right lane is detected, it is determined that the right lane has suddenly changed. It becomes easy to be done.

  As a result, in the second embodiment, when only one lane is detected in the travel lane, the detected lane is regarded as being in an unreliable situation, that is, the possibility that it is a repair mark is high. This makes it easier to determine that the lane is suddenly changing. On the other hand, when one lane is detected in the traveling lane, if the other lane is also detected, it is assumed that the one lane is in a reliable state, that is, the possibility that it is a repair mark is low. It is difficult to determine that one lane is changing suddenly. Thereby, it can prevent more reliably that lane departure prevention control malfunctions based on the repair trace which remains in a driving lane.

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 embodiment, the case where the lane departure prevention control is prohibited is described as the lane departure prevention control is suppressed. However, it is not limited to this. That is, as suppressing the lane departure prevention control, the magnitude of the yaw moment applied to the host vehicle as the lane departure prevention control may be suppressed, or the control start timing of the lane departure prevention control may be delayed.
Moreover, in the said embodiment, determination of the sudden change of a driving lane is performed based on the lane division line formed in the side of the said driving lane. However, it is not limited to this. That is, it is possible to determine a sudden change in the travel lane of another object that forms the travel lane (defines the travel lane).

  In the description of the embodiment, the imaging unit 13 realizes a lane line detection unit that detects a lane line, and the process of step S4 of the braking / driving force control unit 8 is the lane line detection unit. Lane departure tendency determining means for determining the departure tendency of the host vehicle with respect to the traveling lane based on the lane division line detected by the vehicle, and the processing of step S7 and step S8 of the braking / driving force control unit 8 includes the lane When the departure tendency determination means determines that there is a departure tendency, a departure avoidance control means for controlling the own vehicle to avoid the departure of the own vehicle from the traveling lane is realized. The processing of S5 includes lane detection state detection means for detecting the detection state of the lane markings by the lane marking detection means, and the lane detection status detection means. When the detection state of the lane marking detected by the vehicle is in a predetermined state, a lane sudden change determination means for determining that the lane marking is suddenly changed is realized, and step S6 of the braking / driving force control unit 8 is realized. This process realizes a control suppression unit that suppresses the control by the departure avoidance control unit when it is determined that the lane sudden change determination unit is suddenly changing.

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 control unit of the said lane departure prevention apparatus. It is the figure used for description of presumed lateral displacement XsL, XsR. It is the figure used for description of threshold value Xc for departure tendency determination. It is a flowchart which shows the process sequence of the determination process of permission and prohibition of lane departure prevention control by the said control unit. It is a flowchart which shows the process sequence of the sudden change determination process of the lane by the said control unit in 2nd Embodiment.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control unit 8 Braking / driving force control unit 9 Engine 12 Driving torque control unit 13 Imaging unit 14 Navigation device 16 Radar 17 Master cylinder pressure sensor 18 Accelerator opening sensor 19 Steering angle sensor 22FL to 22RR Wheel Speed sensor

Claims (10)

A lane departure tendency determination means for comparing the lateral displacement of the host vehicle with a preset threshold value for determining a departure tendency to determine a departure tendency of the host vehicle with respect to the traveling lane;
When the lane departure tendency determining means determines that there is a departure tendency, departure avoidance control means for controlling the own vehicle to avoid deviation of the own vehicle with respect to the traveling lane;
Lane marking detection means for detecting a lane marking;
Lane detection state detection means for detecting a detection state of a lane marking by the lane marking detection means;
A lane sudden change determination means for determining that the lane division line is suddenly changed when the detection state of the lane division line detected by the lane detection state detection means is a predetermined state;
When it is determined that the lane sudden change determination means is changing suddenly, control suppression means for suppressing control by the departure avoidance control means,
Bei to give a,
The lane detection state detection means detects the detection state of the left and right lane division lines that form a traveling lane,
The lane departure prevention apparatus according to claim 1, wherein the lane sudden change determination means determines whether one lane marking is suddenly changed based on a detection state of the other lane marking.   The lane detection state detection means includes, as a detection state of the lane markings by the lane marking detection means, among the amount of change in the lateral direction, the change speed, and the change direction of the lane marking detected by the lane marking detection means. The lane departure prevention apparatus according to claim 1, wherein at least one of the following is detected.   3. The lane departure according to claim 1, wherein the lane sudden change determination means determines whether or not the lane division line is suddenly changed based on a predetermined threshold for sudden change determination. Prevention device.   4. The lane departure prevention apparatus according to claim 3, wherein the predetermined sudden change determination threshold value is set based on at least one of a yaw angle of the host vehicle with respect to the traveling lane and a host vehicle speed.   The said lane sudden change determination means determines that the said lane division line is changing suddenly, when the said lane division line changes to a driving | running | working lane inside, The one of the Claims 1 thru | or 4 characterized by the above-mentioned. Lane departure prevention device. The lane detection state detection means detects the detection state of the left and right lane markings that make up the driving lane, and the lane sudden change determination means determines whether one of the lane markings changes suddenly based on a predetermined threshold for sudden change determination. 6. The predetermined sudden change determination threshold value is set based on a detection state of the other lane marking line, according to any one of claims 1 to 5 . The lane departure prevention apparatus according to item 1. The predetermined sudden change determination threshold value is set in a direction that makes it easier to determine that the one lane line is suddenly changed when the other lane line is not detected. The lane departure prevention apparatus according to claim 6 . The said control suppression means suppresses the control by the said departure avoidance control means for a predetermined time, after determining that the said lane sudden change determination means is changing suddenly, The any one of Claim 1 thru | or 7 characterized by the above-mentioned. The lane departure prevention apparatus described. Even when the lane departure tendency determination means determines that the lane departure tendency determination means has changed suddenly after the determination that the lane sudden change determination means has changed suddenly, the departure from the lane departure tendency determination means lane departure prevention apparatus according to any one of claims 1 to 8, characterized in that to suppress control by the avoidance control section. The lane departure prevention apparatus according to any one of claims 1 to 9 , wherein the control suppression unit prohibits control by the departure avoidance control unit.

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