JP4475180B2 - Vehicle travel control device - Google Patents

Description

  The present invention relates to a vehicle speed control device that controls the vehicle speed so as to follow the vehicle to be tracked, and when the vehicle tends to deviate from the traveling lane, the vehicle travels by giving a yaw moment to the vehicle. The present invention relates to a vehicle travel control device equipped with a lane departure prevention device for performing lane departure prevention control for preventing departure from a lane.

As a conventional lane departure prevention device, when the host vehicle may deviate from the driving lane, a braking force difference is applied to the left and right wheels, and a yaw moment is applied to the host vehicle, so that the host vehicle moves from the driving lane. There is an apparatus that prevents deviation (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2003-112540

By the way, if the host vehicle tends to deviate during follow-up control to follow the preceding vehicle traveling in front of the host vehicle lane using ACC (Adaptive Cruise Control) or the like, the ACC radar is out of the detection range and the preceding vehicle is lost. In other cases, the radar captures another vehicle traveling in the adjacent lane in the departure direction, thereby recognizing the other vehicle as a tracking target vehicle.
However, in such a situation, even if a yaw moment is applied to the host vehicle to prevent lane departure, the preceding vehicle (original tracking target vehicle) cannot be captured again by the ACC radar, and the preceding vehicle May not be re-recognized by the ACC system as a follow-up target vehicle, or it may take time until it is recognized.

  The present invention has been made in view of the above-described problems. When the own vehicle tends to deviate, the vehicle is out of the radar detection range, and the preceding vehicle traveling in front of the own vehicle lane by ACC is recognized as the following vehicle. An object of the present invention is to provide a travel control device for a vehicle that can reliably recognize the preceding vehicle as a tracking target vehicle after completion of the departure prevention.

The travel control device for a vehicle according to claim 1 recognizes the preceding vehicle detected by the preceding vehicle detection means as a tracking target vehicle, and controls the vehicle speed so as to follow the tracking target vehicle. A vehicle equipped with a lane departure prevention device that performs lane departure prevention control that applies a yaw moment to the host vehicle to prevent the host vehicle from departing from the traveling lane when the host vehicle tends to depart from the traveling lane The travel control device.

In the vehicle travel control device, when the host vehicle tends to deviate and the preceding vehicle detection unit cannot detect a preceding vehicle traveling in front of the host vehicle lane, the preceding vehicle detection unit detects the preceding vehicle lane. Based on the traveling state of the preceding vehicle during the period in which the preceding vehicle traveling ahead is detected, the traveling position of the preceding vehicle when the yaw moment is applied is predicted, and the own vehicle is based on the prediction result By giving a yaw moment to the vehicle , the preceding vehicle detection means can detect the preceding vehicle and give the yaw moment to the own vehicle so that the own vehicle does not deviate from the traveling lane.

  According to the vehicle travel control device of the first aspect, when the departure is prevented, the preceding vehicle can be reliably recognized again as the tracking target vehicle.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
The embodiment is a rear-wheel drive vehicle equipped with a vehicle travel control device 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 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 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, this vehicle is equipped with ACC (adaptive cruise control) for recognizing the preceding vehicle as a tracking target vehicle and controlling the vehicle speed so as to follow the tracking target vehicle. The vehicle has a radar 16 for measuring the distance between the vehicle and the front obstacle by sweeping laser light forward and receiving reflected light from the preceding obstacle for the ACC. Is provided.

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

When the detected vehicle traveling state data has left and right directions, the 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 of lane departure prevention control (as a lane departure prevention device) performed by the braking / driving force control unit 8 will be described with reference to FIG. This calculation process is executed by a timer interrupt every predetermined sampling time ΔT every 10 msec., For example. Although no communication process is provided in the process shown in FIG. 2, information obtained by the arithmetic process is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.

  First, in step S1, various data are read from each sensor, controller, or control unit. Specifically, the longitudinal acceleration Yg, the lateral acceleration Xg, the yaw rate φ ′ and the road information obtained by the navigation device 14, the wheel speeds Vwi, the steering angle δ, the accelerator opening θt, the master cylinder hydraulic pressure detected by the sensors. Pmf, Pmr, direction switch signal, drive torque Tw from the drive torque control unit 12, and yaw angle φ, lateral displacement X, and travel lane curvature β are read from the imaging unit 13.

Subsequently, in step S2, the vehicle speed V is calculated. Specifically, the vehicle speed V is calculated by the following equation (1) based on the wheel speed Vwi read in step S1.
For front wheel drive V = (Vwr1 + Vwrr) / 2
For rear wheel drive V = (Vwfl + Vwfr) / 2
... (1)
Here, Vwfl and Vwfr are the wheel speeds of the left and right front wheels, and Vwrl and Vwrr are the wheel speeds of the left and right rear wheels. That is, in the equation (1), the vehicle speed V is calculated as an average value of the wheel speeds of the driven wheels. In this embodiment, since the vehicle is a rear-wheel drive vehicle, the vehicle speed V is calculated from the latter equation, that is, the wheel speed of the front wheels.

The vehicle speed V calculated in this way is preferably used during normal travel. 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, a lane departure tendency is determined. The procedure of this determination process is specifically as shown in FIG. FIG. 4 shows the definition of values used in this process.

First, in step S21, the estimated lateral displacement Xs of the lateral position of the vehicle center of gravity after a predetermined time is calculated. Specifically, using the yaw angle φ obtained in step S1, the traveling lane curvature β and the lateral displacement X0 of the current vehicle, and the vehicle speed V obtained in step S2, the estimated lateral displacement is expressed by the following equation (2). Xs is calculated.
Xs = Tt · V · (φ + Tt · V · β) + X0 (2)
Here, Tt is the vehicle head time for calculating the forward gaze distance, and when this vehicle head time Tt is multiplied by the own vehicle speed V, it becomes the front gaze distance. That is, the estimated lateral displacement from the center of the traveling lane after the vehicle head time Tt becomes the estimated lateral displacement Xs in the future.

According to the equation (2), the estimated lateral displacement Xs increases as the yaw angle φ increases, for example, when focusing on the yaw angle φ.
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, departure-tendency threshold value X _L is a value indicating the position of the travel path of the boundary line is calculated by the following equation (3).
X _L = (L−H) / 2 (3)

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 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), it determines that there is no lane departure tendency.

Subsequently, in step S23, a departure determination flag Fout is set. That is, if it is determined in step S22 that there is a tendency to depart from the lane (| Xs | ≧ X _L ), the departure determination flag Fout is turned ON (Fout = ON). Further, in step S22, 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 preventing 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 S3.

Subsequently, in step S4, the driver's intention to change lanes is determined. Specifically, the driver's intention to change the lane is determined as follows based on the direction switch signal and the steering angle δ obtained in step S1.
If the direction indicated by the direction switch signal (the blinker lighting side) is the same as the direction indicated by the departure direction Dout obtained in step S3, it is determined that the driver has intentionally changed the lane, and the departure determination flag Fout is changed to OFF (Fout = OFF). That is, it is changed to the determination result that there is no lane departure tendency.

If the direction indicated by the direction switch signal (the blinker lighting side) is different from the direction indicated by the departure direction Dout obtained in step S3, the departure determination flag Fout is maintained and the departure determination flag Fout is kept ON. (Fout = ON). That is, the determination result that there is a tendency to depart from the lane is maintained.
When the direction indicating switch 20 is not operated, the driver's intention to change the lane is determined based on the steering angle δ. That is, when the driver is steering in the departure direction, the driver is conscious when both the steering angle δ and the change amount of the steering angle (change amount per unit time) Δδ are equal to or greater than the set value. And the departure determination flag Fout is changed to OFF (Fout = OFF).

The driver's intention may be determined based on the steering torque.
As described above, when the departure determination flag Fout is ON, when the driver has not intentionally changed the lane, the departure determination flag Fout is maintained ON.
Subsequently, in step S5, if the departure determination flag Fout is ON as a result of the processing in step S4, sound output or display output is performed as an alarm for preventing lane departure.

As will be described later, when the departure determination flag Fout is ON, the application of the yaw moment to the host vehicle is started as the lane departure prevention control, so that the alarm is output at the same time. However, the alarm output timing is not limited to this, and may be earlier than, for example, the start timing of the yaw moment application.
Subsequently, in step S6, it is determined whether or not deceleration control for decelerating the host vehicle is performed as lane departure prevention control. Specifically, the subtraction value obtained by subtracting the lateral displacement limit distance X _L from the estimated lateral displacement Xs calculated in step S3 whether (| | Xs -X _L) is deceleration control determining threshold value X _beta or Determine whether.

Here, the deceleration control determination threshold value _Xβ is a value set according to the travel lane curvature β, and the relationship is as shown in FIG. 5, for example. As shown in FIG. 5, when the travel lane curvature β is small, the deceleration control determination threshold value X _β is a certain large value, and when the travel lane curvature β is greater than a certain value, the travel lane curvature β Accordingly, the deceleration control determination threshold value _Xβ is in an inversely proportional relationship, and when the traveling lane curvature β further increases, the deceleration control determination threshold value _Xβ becomes a certain small value. Furthermore, the deceleration control determination threshold value _Xβ may be set to a smaller value as the vehicle speed V increases.

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

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

In step S7, a yaw moment correction gain is acquired. FIG. 6 shows an example of a procedure for obtaining the yaw moment correction gain, which is performed independently (in parallel) with the flowchart of FIG. Step S7 acquires the processing result of FIG.
First, in step S31, traveling state information of a preceding vehicle is acquired. As the preceding traveling state information, a lateral relative distance and a lateral relative speed with respect to the preceding vehicle detected by the radar 16 under the ACC are acquired.

  Subsequently, in step S32, it is determined whether or not the following target vehicle has been switched. For example, in ACC, a target vehicle follows a preceding vehicle traveling in front of the own vehicle lane (hereinafter referred to as an own vehicle lane preceding vehicle) to another vehicle traveling in an adjacent lane (hereinafter referred to as an adjacent lane preceding vehicle). When switched, a switching signal is output. For this reason, when the switching signal is detected, it is determined that the tracking target vehicle has been switched.

  If it is determined in step S32 that the tracking target vehicle has been switched, the process proceeds to step S33. If it is determined that the tracking target vehicle has not been switched, the processing from step S31 is performed again. That is, the traveling state information of the vehicle preceding the vehicle lane is acquired (for example, data is continuously overwritten) until it is determined that the preceding vehicle (follow-up target vehicle) has been switched.

In step S33, a prediction calculation of the traveling state of the original preceding vehicle (own vehicle lane preceding vehicle) is started. More specifically, the travel direction information of the vehicle lane preceding vehicle acquired in step S32, that is, the lateral direction acquired for the vehicle lane preceding vehicle immediately before the tracking target vehicle is switched (immediately before the switching signal is detected). From the relative distance and the lateral relative speed, the traveling state of the host vehicle lane preceding vehicle during the period in which the adjacent lane leading vehicle is recognized as the tracking target vehicle, specifically, the lateral relative distance to the host vehicle is calculated. More specifically, the lateral displacement Xac of the vehicle preceding the vehicle lane relative to the center line of the vehicle lane is calculated as the lateral relative distance.
Note that the lateral relative distance and the lateral relative speed acquired for the preceding vehicle lane preceding vehicle immediately before the tracking target vehicle is switched are the average values within a predetermined time immediately before the tracking target vehicle is switched. It may be.

  In step S33, a yaw moment correction gain Kcc is acquired based on the lateral displacement Xac calculated as described above. Here, as the lateral displacement Xac (or lateral relative distance) increases, the yaw moment correction gain Kcc also increases (Kcc ≧ 1). FIG. 7 shows such a lateral displacement Xac and yaw moment correction gain Kcc. An example of the relationship is shown. As shown in FIG. 7, when the lateral displacement Xac is small, the yaw moment correction gain Kcc becomes a certain small value, and when the lateral displacement Xac exceeds a certain value, the lateral displacement Xac and the yaw moment correction gain Kcc Is proportional, and when the lateral displacement Xac further increases, the yaw moment correction gain Kcc has a certain large value.

  In the present embodiment, the target yaw moment Ms to be applied to the host vehicle as lane departure prevention control is corrected using the yaw moment correction gain Kcc, as will be described later. This is performed only when the preceding vehicle lane preceding vehicle is located on the departure avoidance side of the own vehicle with respect to the own vehicle. For example, when the host vehicle tends to deviate in the right direction, the correction is performed when the host vehicle lane preceding vehicle is positioned on the left side that is the departure avoidance side of the host vehicle.

  For this reason, the lateral relative distance is a distance on the deviation avoidance side of the own vehicle with respect to the own vehicle, and the lateral displacement Xac is a deviation of the own vehicle with respect to the center line of the own vehicle lane. Displacement to the avoidance side. Further, when the vehicle ahead of the vehicle lane is approaching the departure side of the vehicle in the vehicle lane, that is, when the lateral relative distance is a distance on the departure side of the vehicle relative to the vehicle, the lateral displacement Xac Is displaced toward the departure side of the host vehicle with respect to the center line of the host vehicle lane, the yaw moment correction gain Kcc is 1.

Thereafter, in step S34, it is determined whether or not a predetermined time has passed. If the predetermined time has passed, the yaw moment correction gain Kcc is set to 1 in step S35.
Subsequently, in step S8, a target yaw moment Ms to be applied to the vehicle as lane departure prevention control is calculated.
Specifically, calculates target yaw moment Ms by the following equation (4) based on the yaw moment correction gain Kcc obtained by the estimated lateral displacement Xs and lateral displacement limit distance X _L, as well as the step S7 obtained in step S3 To do.
Ms = Kcc · K1 · K2 · (| Xs | −X _L ) (4)

  Here, K1 is a proportional gain determined from vehicle specifications, and K2 is a gain that varies according to the vehicle speed V. FIG. 8 shows an example of the gain K2. As shown in FIG. 8, when the host vehicle speed V is small, the gain K2 is a certain large value. When the host vehicle speed V is greater than a certain value, the gain K2 increases with respect to the host vehicle speed V. Accordingly, when the host vehicle speed V further increases, the gain K2 becomes a certain small value.

The equation (4), the larger the difference between estimated lateral displacement Xs and lateral displacement limit distance X _L is, target yaw moment Ms becomes larger. The target yaw moment Ms increases as the yaw moment correction gain Kcc increases, that is, as the lateral displacement Xac increases.
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.

  Also, if it is not determined that there is a tendency to deviate from the lane preceding vehicle to the adjacent lane preceding vehicle from the host vehicle lane preceding vehicle, if the vehicle is not determined to have a lane departure tendency, The value of the lateral displacement Xac is updated based on the traveling state information of the vehicle lane preceding vehicle, and the yaw moment correction gain Kcc is also updated. Then, the target yaw moment Ms is calculated using the latest yaw moment correction gain Kcc at the determination timing that the lane departure tendency is present (the timing when the departure determination flag Fout is turned ON).

Subsequently, in step S9, the deceleration of the deceleration control that has been determined to be feasible in step S6 is calculated. That is, the braking force applied to the left and right wheels for the purpose of decelerating the host vehicle is calculated. Here, the target braking fluid pressures Pgf and Pgr that give such braking force to both the left and right wheels are calculated. The target braking hydraulic pressure Pgf for the front wheels is calculated by the following equation (5).
Pgf = Kgv · Kgb · (| Xs | −X _L −X _β ) (5)

  Here, Kgv is a proportional gain set according to the host vehicle speed V, and Kgb is a proportional gain determined by vehicle specifications. FIG. 9 shows an example of the proportional gain Kgv. As shown in FIG. 9, when the host vehicle speed V is small, the gain Kgv is a certain small value. When the host vehicle speed V is greater than a certain value, the gain Kgv and the host vehicle speed V are in a proportional relationship, and the host vehicle speed V When becomes further larger, the gain Kgv becomes a certain large value.

Then, based on the target braking hydraulic pressure Pgf for the front wheels, the target braking hydraulic pressure Pgr for the rear wheels considering the front-rear distribution is calculated.
As described above, in step S9, deceleration for preventing lane departure (specifically, target braking hydraulic pressures Pgf and Pgr) is obtained.
Subsequently, in step S10, a target brake hydraulic pressure for each wheel is calculated. That is, the final braking fluid pressure is calculated based on the presence or absence of braking control for preventing lane departure. Specifically, it is calculated as follows.

When the departure determination flag Fout is OFF, that is, when the determination result that there is no lane departure tendency is obtained, as shown in the following expressions (6) and (7), the target brake hydraulic pressure Psi (i = fl, fr, rl, rr) are set to the brake fluid pressures Pmf, Pmr.
Psfl = Psfr = Pmf (6)
Psrl = Psrr = Pmr (7)
Here, Pmf is the brake fluid pressure for the front wheels. Further, Pmr is the braking fluid pressure for the rear wheels, and is a value calculated based on the braking fluid pressure Pmf for the front wheels in consideration of the front-rear distribution. For example, if the driver is performing a brake operation, the brake fluid pressures Pmf and Pmr are values corresponding to the operation amount of the brake operation.

On the other hand, when the departure determination flag Fout is ON, that is, when a determination result that there is a lane departure tendency is obtained, first, based on the target yaw moment Ms, the front wheel target braking hydraulic pressure difference ΔPsf and the rear wheel target braking hydraulic pressure difference ΔPsr are set. calculate. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (8) to (11).
When | Ms | <Ms1, ΔPsf = 0 (8)
ΔPsr = Kbr · Ms / T (9)
When | Ms | ≧ Ms1 ΔPsf = Kbf · (Ms / | Ms |) · (| Ms | −Ms1) / T (10)
ΔPsr = Kbr · (Ms / | Ms |) · Ms1 / T (11)
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 on the wheels is distributed according to the magnitude of the target yaw moment Ms. When the target yaw moment Ms is less than the setting threshold value Ms1, the front wheel target braking hydraulic pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking hydraulic pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. Further, when the target yaw moment Ms is equal to or larger than the setting threshold value Ms1, a predetermined value is given to each target braking hydraulic pressure difference ΔPsr, ΔPsr, and a braking force difference is generated between the front, rear, left and right wheels.

  Then, the final target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated using the target brake fluid pressure differences ΔPsf, ΔPsr calculated as described above and the target brake fluid pressures Pgf, Pgr for deceleration. ) Is calculated. Specifically, the final target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated with reference to the deceleration control operation determination flag Fgs obtained in step S7.

That is, when the departure determination flag Fout is ON, that is, a determination result that there is a lane departure tendency is obtained, but when the deceleration control operation determination flag Fgs is OFF, that is, when only the yaw moment is applied to the vehicle, The target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (12).
Psfl = Pmf
Psfr = Pmf + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
(12)

Further, when the departure determination flag Fout is ON and the deceleration control operation determination flag Fgs is ON, that is, when the vehicle is decelerated while giving the yaw moment, the target of each wheel is expressed by the following equation (13). The brake fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pmf + Pgf / 2
Psfr = Pmf + ΔPsf + Pgf / 2
Psrl = Pmr + Pgr / 2
Psrr = Pmr + ΔPsr + Pgr / 2
... (13)

  Further, as shown by the equations (12) and (13), 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.

With the processing as described above, the following series of operations are performed.
First, various data are read from each sensor or the like (step S1), and the vehicle speed V is calculated (step S2).
Subsequently, a lane departure tendency is determined, and when there is a lane departure tendency, the departure determination flag Fout is turned on to further detect the departure direction Dout, and when there is no lane departure tendency, the departure determination flag Fout is turned off. (Step S3). Even when the departure determination flag Fout is turned ON, the driver's intention to change the lane is determined. If the driver has an intention to change the lane, the departure determination flag Fout is changed to OFF, If there is no intention to change, the departure determination flag Fout is kept ON (step S4).

When the departure determination flag Fout is ON, a warning is output (step S5).
On the other hand, it is determined whether or not to perform deceleration control for decelerating the vehicle as lane departure prevention control (step S6). Here, when performing deceleration control, the deceleration control operation determination flag Fgs is turned ON to calculate the deceleration of the deceleration control (steps S6 and S9). On the other hand, when deceleration control is not performed, the deceleration control operation determination is performed. The flag Fgs is turned off (step S6).

  Further, a target yaw moment Ms to be given to the host vehicle as lane departure prevention control is calculated (step S8). At this time, the target yaw moment Ms is corrected by the yaw moment correction gain Kcc set in accordance with the lateral displacement Xac (see the above equation (4)). By this correction, the target yaw moment Ms is corrected so as to increase as the lateral displacement Xac of the original preceding vehicle (own vehicle lane preceding vehicle) increases or as the original preceding vehicle moves away from the own vehicle in the lateral direction. Is done.

  When the departure determination flag Fout is ON, braking force is generated on the wheels so that the target yaw moment Ms is applied to the host vehicle as lane departure prevention control, and when the deceleration control operation determination flag Fgs is ON, As the lane departure prevention control, a braking force is generated on the wheels so that the host vehicle decelerates (step S10). As a result, when there is a tendency to depart from the lane, a yaw moment is applied to the host vehicle, and the host vehicle decelerates before the yaw moment is applied.

Here, the vehicle operation realized by the above-described processing will be described with reference to FIG.
When the ACC recognizes the vehicle lane preceding vehicle 101 as the vehicle to be tracked and controls the vehicle 100 to follow the vehicle ((a) in the figure), when the yaw angle in the adjacent lane direction of the vehicle 100 increases, The ACC radar 16 of the host vehicle 100 recognizes the adjacent lane leading vehicle 102, and the vehicle to be tracked by ACC is switched from the own lane leading vehicle 101 to the adjacent lane leading vehicle 102 ((b) in the figure). Then, immediately before the switching, the own vehicle 100 acquires the lateral relative distance and the lateral relative speed with the own vehicle lane preceding vehicle 101 as the traveling state information of the own vehicle lane preceding vehicle 101. Then, the yaw moment correction gain Kcc is calculated based on the traveling state information of the vehicle lane preceding vehicle 101.

  If the yaw angle in the adjacent lane direction of the host vehicle 100 increases and the host vehicle 100 has a tendency to depart from the lane, the target yaw is calculated using the yaw moment correction gain Kcc calculated at that time. The moment Ms is calculated. The target yaw moment Ms calculated at this time is the lateral direction of the vehicle lane preceding vehicle 101 as shown as a change from the vehicle lane preceding vehicle 101 in the solid line to the vehicle lane preceding vehicle 101 in the dotted line in FIG. In consideration of the movement to the vehicle, the value is calculated so that the ACC radar 16 can recognize the vehicle lane preceding vehicle 101 as the tracking target vehicle.

As a result, when yaw moment is applied to the host vehicle 100 as lane departure prevention control, the ACC radar 16 of the host vehicle 100 can reliably re-recognize the host vehicle lane preceding vehicle 101 as the tracking target vehicle (same as above). Figure (c)).
Thereby, the tracking control by ACC becomes possible immediately after the departure prevention by the lane departure prevention control is completed. For example, as compared with the case where a lane departure tendency is detected (before the lane departure prevention control), the inter-vehicle distance from the preceding vehicle lane preceding vehicle 101 immediately after completion of the departure prevention by the lane departure prevention control is closer. Even in this case, the tracking control by the ACC is surely activated immediately after the completion of the departure prevention, so that the host vehicle 100 is controlled to be decelerated and the inter-vehicle distance is secured.

In the present invention, as shown in FIG. 10, the own vehicle lane leading vehicle 101 is traveling in the driving lane toward the side far from the adjacent lane leading vehicle 102 (lane departure avoiding direction) Particularly effective when the lane leading vehicle 102 is traveling closer to the own vehicle lane in the adjacent lane, or the adjacent lane leading vehicle 102 has a shorter inter-vehicle distance from the own vehicle 100 than the own vehicle lane leading vehicle 101. Act on.
For example, as shown in FIG. 11, when the own vehicle lane preceding vehicle 101 and the adjacent lane preceding vehicle 102 are running in parallel, that is, the own lane preceding vehicle 101 is more than the adjacent lane preceding vehicle 102. The present invention works even when the inter-vehicle distance to 100 is short.

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 embodiment, it is assumed that the tracking target vehicle is switched from the preceding vehicle lane leading vehicle to the adjacent lane leading vehicle, but even in the case of lost that the tracking target vehicle is simply lost. The present invention can be applied.

  In the description of the above embodiment, the processing of step S31 and step S32 by the braking / driving force control unit 8 is a travel that stores travel state information of a preceding vehicle that travels ahead of the host vehicle lane detected by the preceding vehicle detection means. The state information storage means is realized, and the prediction calculation process of the traveling state of the original preceding vehicle in step S33 by the braking / driving force control unit 8 is performed by the preceding vehicle in which the preceding vehicle detection means travels ahead of the own vehicle lane. When the vehicle state cannot be detected, a driving state prediction unit that predicts the driving state of the preceding vehicle is realized based on the driving state information stored in the driving state information storage unit, and a braking / driving force control unit 8, the target yaw moment Ms based on the yaw moment correction gain Kcc in step S8. The calculation process realizes a yaw moment correction unit that corrects the yaw moment so that the preceding vehicle detection unit can detect the preceding vehicle based on the traveling state of the preceding vehicle predicted by the traveling state prediction unit. ing.

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 which comprises the said lane departure prevention apparatus. It is a flowchart which shows the processing content of determination of the lane departure tendency by the said control unit. It is a diagram used for explanation of the estimated lateral displacement Xs and deviation judgment threshold value X _L. FIG. 6 is a characteristic diagram showing a relationship between a travel lane curvature β and a deceleration control determination threshold value _Xβ . It is a flowchart which shows the processing content which calculates the gain Kcc for yaw moment correction | amendment by the said control unit. FIG. 6 is a characteristic diagram illustrating a relationship between a lateral displacement Xac and a yaw moment correction gain Kcc. It is a characteristic view which shows the relationship between the vehicle speed V and the gain K2. It is a characteristic view which shows the relationship between the vehicle speed V and the gain Kgv. It is the figure used for description of operation | movement of the own vehicle implement | achieved by this invention. It is the figure used for description of operation | movement of the own vehicle in the other driving | running | working scene implement | achieved by this invention.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control unit 8 Braking / driving force control unit 9 Engine 12 Drive torque control unit 13 Imaging unit 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 (4)

A vehicle speed control device that recognizes the preceding vehicle detected by the preceding vehicle detection means as the tracking target vehicle and controls the vehicle speed so as to follow the tracking target vehicle, and the host vehicle tends to deviate from the traveling lane. A travel control device for a vehicle equipped with a lane departure prevention device that performs lane departure prevention control that applies a yaw moment to the host vehicle to prevent the host vehicle from departing from the travel lane,

When the host vehicle tends to deviate and the preceding vehicle detection unit cannot detect a preceding vehicle traveling in front of the own vehicle lane, the preceding vehicle detection unit detects a preceding vehicle traveling in front of the own vehicle lane. By predicting the traveling position of the preceding vehicle when the yaw moment is applied based on the traveling state of the preceding vehicle during the running period, and applying the yaw moment to the host vehicle based on the prediction result the preceding vehicle detection means can detect the preceding vehicle, and as the vehicle does not deviate from the traveling lane, the travel control device for a vehicle, characterized in that the yaw moment is applied to the vehicle.

A vehicle speed control device that recognizes the preceding vehicle detected by the preceding vehicle detection means as the tracking target vehicle and controls the vehicle speed so as to follow the tracking target vehicle, and the host vehicle tends to deviate from the traveling lane. A travel control device for a vehicle equipped with a lane departure prevention device that performs lane departure prevention control that applies a yaw moment to the host vehicle to prevent the host vehicle from departing from the travel lane,

  Traveling state information storage means for storing traveling state information of a preceding vehicle traveling in front of the host vehicle lane detected by the preceding vehicle detection means;

  When the preceding vehicle detection unit can no longer detect a preceding vehicle traveling in front of the host vehicle lane, the traveling state of the preceding vehicle is determined based on the traveling state information stored in the traveling state information storage unit. A running state predicting means for predicting;

  Yaw moment correcting means for correcting the yaw moment so that the preceding vehicle detecting means can detect the preceding vehicle based on the running state of the preceding vehicle predicted by the running state predicting means;

  A vehicle travel control device comprising:

The travel state information storage means stores a lateral relative movement amount and a lateral relative distance between the preceding vehicle and the host vehicle as the travel state information, and the travel state prediction means stores the lateral relative movement amount. And the relative positional relationship between the preceding vehicle and the host vehicle is predicted based on the relative distance in the lateral direction, and the yaw moment correcting means corrects the yaw moment based on the relative positional relationship. The vehicle travel control apparatus according to claim 2, wherein:

When the preceding vehicle detection unit cannot detect a preceding vehicle traveling in front of the own vehicle lane, the detection target by the preceding vehicle detection unit is a departure tendency from the preceding vehicle traveling in front of the own vehicle lane. 4. The vehicle travel control device according to claim 1, wherein the vehicle travel control device is switched to a preceding vehicle that travels in an adjacent lane on the side of the vehicle.

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