JP5234142B2 - Lane departure prevention device - Google Patents

Description

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

  As a conventional lane departure prevention device, when the host vehicle may deviate from the driving lane, 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

When the brake is cold immediately after the start of the vehicle, the brake braking force is reduced, so that a sufficient yaw moment cannot be obtained, and thus the desired lane departure prevention control may not be realized. This is because the temperature of the brake shoe (or brake pad) is mainly affected, and the desired braking characteristics cannot be obtained because the brake shoe is still in a low temperature state.
The control amount calculation in the lane departure prevention apparatus is performed based on the relationship between the lane marker detected by the camera (running lane) and the vehicle state (lateral position, departure angle, etc.). Based on the relationship, the necessary yaw moment (target yaw moment) is calculated, and the brake fluid pressure based on the yaw moment command value based on the calculated value is applied to the brakes of each wheel by the brake actuator. The vehicle generates a yaw moment in the direction of avoiding lane departure.

  Therefore, if the departure situation is the same, the calculated yaw moment command value (target yaw moment) is calculated as a similar value, and the brake fluid pressure is also the same value. However, when the vehicle is cold (when the brake is cold), as long as the brake fluid pressure is the same, the yaw moment applied to the host vehicle changes as a result of the decrease in the brake braking force as described above. (It will drop).

Here, as a measure to prevent such a problem, the yaw moment generated in the host vehicle is detected by the lane departure prevention control, and the difference between the detected yaw moment (actual yaw moment) and the yaw moment command value is calculated. It is conceivable to perform lane departure prevention control by feedback. However, in the lane departure prevention control, when the host vehicle may deviate from the driving lane, the control continuation time until the lane departure prevention is completed is short because it is necessary to immediately prevent the lane departure prevention. Even so, it is difficult to sufficiently obtain the feedback effect.
The present invention has been made in view of the above-described problems, and can suppress the influence of a decrease in brake braking force when the brake is cold, and can impart a desired yaw moment to the host vehicle as lane departure prevention control. The object is to provide a lane departure prevention device.

Claim 1 lane departure prevention apparatus described, when the own vehicle relative to the traffic lane in departure tendency, a yaw moment to the vehicle in Rukoto to generate a braking force difference to left and right wheels wheels by the braking force generating means A lane departure prevention device that performs lane departure prevention control that is provided to prevent the vehicle from deviating from the traveling lane.
The lane departure prevention device changes the control amount of the lane departure prevention control in a direction to increase the braking force difference when the temperature of the braking force generation unit is lower than the temperature at which the braking force generation unit can optimally operate. .

According to the lane departure prevention apparatus according to claim 1, when the temperature of the braking force generation unit is lower than the temperature at which the braking force generation unit can operate normally, the control amount of the lane departure prevention control is increased by the braking force difference. By changing the direction to the desired direction, it is possible to compensate for the temperature dependence of the braking force generation means and to realize the desired lane departure prevention control.

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 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 steering angle δ, a host vehicle speed V, and a target yaw rate φ ′ ^* . FIG. 5 is a characteristic diagram showing a relationship between a travel lane curvature β and a deceleration control determination threshold value Xβ. It is a characteristic view which shows the relationship between the own vehicle speed V and the gain K2. It is a characteristic view which shows the relationship between the own vehicle speed V and the gain Kv. It is a flowchart which shows the correction process at the time of brake cold by a control unit. FIG. 6 is a characteristic diagram showing a relationship between a detected brake pressure value Psmc and a brake pressure value Pcmc. It is a characteristic view which shows the relationship between the own vehicle speed V and the subtraction value PGsmc. It is a characteristic view showing the relationship between the brake energy evaluation index value Ecbr and the brake cold time adjustment gain Kcbr. FIG. 6 is a characteristic diagram showing a relationship between a state of a brake determination flag Fem and an upper limit value Ms2. It is the figure used for description of the vehicle operation | movement at the time of lane departure prevention control. It is a characteristic view showing the relationship between the brake energy evaluation index value Ecbr and the vehicle head time Tt for calculating the forward gaze distance. FIG. 6 is a characteristic diagram showing a relationship between a brake energy evaluation index value Ecbr and a departure tendency determination threshold value X _L.

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

FIG. 1 is a schematic configuration diagram showing the 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 is 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.

Furthermore, a switch (not shown) is provided so that the driver can change the starting position of the lane departure prevention control as desired. For example, the start position of the lane departure prevention control can be changed as desired by the driver by making the departure determination threshold value changeable by a switch. The switch switching signal is output to the braking / driving force control unit 8.
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 right direction is the positive direction in all cases. That is, the yaw rate φ ′, the lateral acceleration Xg, and the yaw angle φ are positive values when turning right, and the lateral displacement X is a positive value when deviating from the center of the traveling lane to the right. The longitudinal acceleration Yg takes a positive value during acceleration and takes a negative value during deceleration.
Next, a calculation processing procedure performed by the braking / driving force control unit 8 will be described with reference to FIG. This calculation process is executed by a timer interrupt every predetermined sampling time ΔT every 10 msec., For example. Although no communication process is provided in the process shown in FIG. 2, information obtained by the arithmetic process is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.

First, in step S1, various data are read from each sensor, controller, or control unit. Specifically, the longitudinal acceleration Yg, lateral acceleration Xg, yaw rate φ ′ and road information obtained by the navigation device 14, road speed Vwi, steering angle δ, accelerator opening θt, master cylinder hydraulic pressure detected by each sensor The Pm and direction switch signals, the driving torque Tw from the driving torque control unit 12, and the yaw angle φ, the lateral displacement X, and the 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 future estimated lateral displacement (deviation estimated value) Xs is calculated as the estimated deviation value. FIG. 3 illustrates definitions of values used for the calculation.

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.
As will be described later, when the estimated lateral displacement Xs is equal to or greater than a predetermined threshold value (departure tendency determination threshold), the host vehicle may depart from the travel lane, or the host vehicle is in the travel lane. Is determined to deviate from

Subsequently, in step S4, the turning state of the host vehicle is determined. Specifically, it is determined whether or not the absolute value of the lateral acceleration Xg read in step S1 is equal to or greater than a turning determination threshold value (positive value) Xg0. Here, if the absolute value of the lateral acceleration Xg is equal to or greater than the turning judgment threshold value (positive value) Xg0 (| Xg | ≧ Xg0), the vehicle stability judgment flag Fcs is set assuming that the host vehicle is in a sudden turning state. (Fcs = ON), if the absolute value of the lateral acceleration Xg is less than the turning judgment threshold value (positive value) Xg0 (| Xg | <Xg0), the vehicle stability judgment flag is determined that the host vehicle is not in a sudden turning state. Fcs is reset (Fcs = OFF).
Note that the turning state of the host vehicle is not limited to the determination based on the lateral acceleration Xg as described above. For example, the determination may be made based on the yaw rate φ ′ of the host vehicle. In this case, it is performed by comparing the yaw rate φ ′ read in step S1 with the target yaw rate estimated from the current host vehicle state. Here, as shown in FIG. 4, the target yaw rate φ ′ ^* is obtained based on the vehicle speed V and the steering angle δ. In FIG. 4, the target yaw rate φ ′ ^* increases as the steering angle δ increases or the host vehicle speed V increases.

Then, the target yaw rate thus obtained and the yaw rate φ ′ are compared to determine whether the vehicle is in a steer state, so-called oversteer or understeer, and a vehicle stability determination flag Fcs is set based on the determination result. For example, in the case of oversteer or understeer, the vehicle stability determination flag Fcs is set (Fcs = ON).
Further, the vehicle stability determination flag Fcs may be set independently based on the determination result by the yaw rate φ ′, and the determination result by the lateral acceleration Xg as described above is comprehensively evaluated. Finally, the vehicle stability determination flag Fcs may be set.
Subsequently, in step S5, the driver's intention to change lanes is determined. Specifically, based on the sign of the estimated lateral displacement Xs obtained in step S3 (positive in the right direction and negative in the left direction), the direction switch signal, and the steering angle δ, the driver's lane change is performed as follows. Determine your intention.

When the direction indicated by the direction switch signal (the blinker lighting side) and the direction indicated by the estimated lateral displacement Xs (symbol) are the same, the lane change intention determination flag _FLC is set on the assumption that the driver intends to change the lane. and (F _LC = oN), if the direction indicated by the estimated lateral displacement Xs and the direction indicated by the directional switch signal (lighted blinker side) (code) is different, as no intention to change lanes to the driver, the lane change intent The judgment flag F _LC is reset (F _LC = OFF).
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. For example, when the turning direction of the host vehicle by the steering angle δ is the same as the direction (symbol) indicated by the estimated lateral displacement Xs, the steering angle δ and the change amount of the steering angle (change amount per unit time) If both Δδ and the set value are greater than or equal to the set value, it is determined that the driver intends to change lanes, and a lane change intention determination flag F _LC is set (F _LC = ON).

Subsequently, in step S6, it is determined whether or not to warn that the host vehicle is in a tendency to deviate from the traveling lane. Specifically, the absolute value | Xs | of the estimated lateral displacement Xs calculated in the step S3 is compared with a predetermined deviation tendency determination threshold value X _L to make the determination.
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, as shown in FIG. 3, the departure tendency determination threshold value X _L is a value indicating the position of the boundary line of the traveling road, and is calculated by the following equation (3), for example.
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 position of the host vehicle 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. Further, the departure tendency determination threshold value X _L may be a fixed value, for example, 0.8 m.
In step S6, the absolute value of the estimated lateral displacement Xs | is equal to or greater than the threshold value X _L for determining the tendency to deviate | Xs (| Xs | ≧ X L), and alarm output, the absolute value of the estimated lateral displacement Xs | Xs When | is less than the deviation tendency determination threshold value X _L (| Xs | L <X _L ), no alarm is output.
Subsequently, in step S7, the brake operation state of the driver is determined.
Here, first, based on the master cylinder hydraulic pressure Pm read in step S1, an increase rate ΔPm of the master cylinder hydraulic pressure Pm is calculated by the following equation (4).
ΔPm = (Pm _Z −Pm _Z−1 ) / Ct (4)
Here, Pm _Z is the current master cylinder pressure, and Pm _Z-1 is the master cylinder hydraulic pressure during the previous control cycle. Ct is a control (processing) cycle time, for example, 10 msec.

  Subsequently, it is determined whether or not the increase rate ΔPm of the master cylinder pressure calculated by the equation (4) is equal to or greater than the brake operation determination threshold value ΔPmth. Here, when the rate of increase ΔPm of the master cylinder pressure is equal to or greater than the brake operation determination threshold value ΔPmth (ΔPm ≧ ΔPmth), the emergency brake determination flag Fcm is set assuming that the driver's brake operation is urgent (Fcm = ON), when the increase rate ΔPm of the master cylinder pressure is less than the brake operation determination threshold value ΔPmth (ΔPm <ΔPmth), the emergency brake determination flag Fem is reset assuming that the driver's brake operation is not urgent (Fem = OFF). If the driver's brake operation is not urgent (Fem = OFF), the lane departure prevention control processing shown in FIG.

Subsequently, in step S8, it is determined whether or not the host vehicle tends to deviate from the traveling lane. Specifically, similarly to the processing in step S6, the absolute value of the estimated lateral displacement Xs calculated in step S3 | Xs | compares with a predetermined departure-tendency threshold value X _L, the determination I do. Here, when the absolute value | Xs | of the estimated lateral displacement Xs is equal to or greater than the departure tendency determination threshold value X _L (| Xs | ≧ X _L ), it is assumed that the host vehicle tends to depart from the travel lane. When the determination flag Fout is set (Fout = ON) and the absolute value | Xs | of the estimated lateral displacement Xs is less than the deviation tendency determination threshold value X _L (| Xs | <X _L ), the host vehicle is in the travel lane. On the other hand, the departure determination flag Fout is reset assuming that there is no departure tendency (Fout = OFF).

Also, if you set the vehicle stability determination flag Fcs in step S4 (Fcs = ON), or if you set the lane change intention determination flag F _LC in step S5 (F _LC = ON), the lane departure as not performed prevention control, the absolute value of the estimated lateral displacement Xs | Xs | even if the above departure-tendency threshold value X _L, to reset the departure flag Fout (Fout = OFF).
Subsequently, in step S9, it is determined whether or not to perform deceleration control for decelerating the host vehicle (hereinafter referred to as lane departure prevention deceleration control) as lane departure prevention control. Specifically, the subtraction value (| Xs | −X _L ) obtained by subtracting the departure tendency determination threshold value X _L from the estimated lateral displacement Xs calculated in step S3 is equal to or greater than the deceleration control determination threshold value Xβ. It is determined whether or not.

Here, the deceleration control determination threshold value Xβ is a value set according to the travel lane curvature β read in step S1, and the relationship is as shown in FIG. 5, for example. As shown in FIG. 5, when the traveling lane curvature β is small, the deceleration control determination threshold value Xβ is a certain large value, and when the traveling lane curvature β is larger than a certain value, the traveling lane curvature β increases. On the other hand, when the deceleration control threshold value Xβ decreases and the travel lane curvature β further increases, the deceleration control determination threshold value Xβ becomes a certain small value. Further, the deceleration control determination threshold value Xβ may be set to a smaller value as the vehicle speed V increases.
In this step S9, when the subtraction value (| Xs | −X _L ) is equal to or larger than the deceleration control determination threshold value Xβ (| Xs | −X _L ≧ Xβ), it is determined that the deceleration control is performed and the deceleration is performed. When the control operation determination flag Fgs is set (Fgs = ON) and the subtraction value (| Xs | −X _L ) is less than the deceleration control determination threshold value Xβ (| Xs | −X _L <Xβ), deceleration is performed. In addition to determining not to perform control, the deceleration control operation determination flag Fgs is reset (Fgs = OFF).

Further, according to FIG. 5, in the driving scene such that a sharp curve appears in front of the host vehicle, the threshold Xβ for deceleration control determination decreases as the driving lane curvature β increases, so the subtraction value (| Xs | −X _L ) is likely to be equal to or greater than the deceleration control determination threshold value Xβ, that is, the deceleration control operation determination flag Fgs is easily set.
Subsequently, in step S10, various gains used for calculation of lane departure prevention control are set. Specifically, a gain K1 determined by vehicle specifications and gains K2 and Kv determined by own vehicle speed V are set.
FIG. 6 shows an example of the gain K2, and FIG. 7 shows an example of the gain Kv. As shown in FIG. 6, when the host vehicle speed V is small, the gain K2 becomes a certain large value. When the host vehicle speed V exceeds a certain value, the host vehicle speed V increases while the gain K2 decreases. When the host vehicle speed V further increases, the gain K2 becomes a certain small value. Further, as shown in FIG. 7, when the host vehicle speed V is low, the gain Kv is a certain small value. When the host vehicle speed V is greater than a certain value, the gain Kv increases as the host vehicle speed V increases. As V further increases, the gain Kv becomes a certain large value.

Subsequently, in step S11, a target yaw moment Ms used for control for giving a yaw moment to the host vehicle as the lane departure prevention control (hereinafter referred to as lane departure prevention yaw control) is calculated.
Specifically, based on the estimated lateral displacement Xs obtained in step S3, the lateral displacement limit distance X _L used in the processing in steps S6 and S8, and the gains K1 and K2 obtained in step S9, the following (5 ) To calculate the target yaw moment Ms.
Ms = −K1 · K2 · (Xs−X _L ) (5)
The calculation of the target yaw moment Ms according to the equation (5) is performed when the departure determination flag Fout is ON, and when the departure determination flag Fout is OFF, the target yaw moment Ms is set to 0.

Subsequently, in step S12, a brake cold correction process is performed. FIG. 8 shows an example of the processing procedure.
First, in step S31, the engine water temperature is read. Subsequently, in step S32, the engine water temperature is determined. Here, the engine water temperature Tew is compared with a predetermined threshold value (experimental value, experience value, etc.) Thethh. If the engine water temperature Tew is lower than the predetermined threshold value Tewth (Tew <Tewth), the process proceeds to Step S33. When the engine coolant temperature Tew is equal to or higher than a predetermined threshold value Tewth (Tew ≧ Tewth), the process proceeds to step S34.
In step S33, an immediately after engine start flag Fengst indicating immediately after engine start is set (Fengst = ON). Then, the process proceeds to step S34. In cases other than immediately after the engine is started, step S33 is not performed, so the flag immediately after the engine start Fengst remains reset (Fengst = OFF).

In step S34, it is determined whether the brake is operating or not. Here, when the brake fluid pressure is equal to or higher than a predetermined value, it is determined that the brake is in an operating state. Note that the brake operating state may be determined using a brake stroke sensor, a brake pedal switch, or the like.
If it is determined in this step S34 that the brake is in operation, the process proceeds to step S35, and if it is determined that the brake is not operated, the process proceeds to step S37.
In step S35, a brake pressure detection value (brake fluid pressure value) is read. Subsequently, in step S36, a brake pressure value (brake evaluation value) Pcmc used for calculation of a brake energy evaluation index value Ecbr in step S41 described later is calculated using the detected brake pressure value (actual value) read in step S35. To do.

Specifically, the calculation is performed based on the set state of the engine start flag Fengst set in step S33, that is, when the engine start flag Fengst is set (Fengst = ON), the brake pressure The value Pcmc is set by the following equation (6), and when the engine start flag Fengst is in the reset state (Fengst = OFF), the brake pressure value Pcmc is set by the following equation (7).
Pcmc = Psmc × Kengst (Fengst = ON) (6)
Pcmc = Psmc (Fengst = OFF) (7)

Here, Psmc is a brake pressure detection value (brake fluid pressure value), Kengst is a gain, and takes a value between 0 and 1 (0 <Kengst <1). FIG. 9 shows the relationship between the detected brake pressure value Psmc and the brake pressure value Pcmc. As shown in FIG. 9, the brake pressure value Pcmc is proportional to the detected brake pressure value Psmc. Further, in a comparison between immediately after engine start (Fengst = ON) and other than immediately after engine start (Fengst = OFF), the brake pressure value Pcmc is smaller immediately after engine start.
After calculating the brake pressure value Pcmc in step S36 as described above, the calculated brake pressure value Pcmc is stored, and the process proceeds to step S41.
On the other hand, in step S37 which proceeds when it is determined in step S34 that the brake is not in operation, it is determined whether or not the wiper is operating. If the wiper is in operation, the process proceeds to step S38. If the wiper is inactive, the process proceeds to step S39.

In step S38, the wiper operation flag Fwp is set (Fwp = ON). Then, the process proceeds to step S39. When the wiper is not operating, step S38 is not performed, and therefore the wiper operation flag Fwp remains reset (Fwp = OFF).
In step S39, the host vehicle speed is read. Subsequently, in step S40, a subtraction amount PGcmc used for calculation of a brake energy evaluation index value Ecbr in step S41 described later is calculated.
The calculation is performed based on the set state of the wiper operation flag Fwp set in step S37, that is, when the wiper operation flag Fwp is set (Fwp = ON), the subtraction amount PGcmc is expressed by the following equation (8). When the wiper operation flag Fwp is in the reset state (Fwp = OFF), the subtraction amount PGcmc is set by the following equation (9).

PGcmc = PGsmc La Kwp (Fwp = ON) (8)
PGcmc = PGsmc (Fwp = OFF) (9)
Here, PGsmc is a subtraction value (initial value of the subtraction value) determined according to the vehicle speed read in step S39. Further, KWP is I gain der, it is larger than 1 (Kwp> 1). For example, as shown in FIG. 10, the subtraction value PGsmc is proportional to the host vehicle speed V, and becomes a limit value (a constant value) in each of the extremely low speed range and the high speed range. Further, in the comparison between the wiper operating state (Fwp = ON) and the wiper non-operating state (Fwp = OFF), since the gain Kwp is larger than 1, the subtraction amount PGsmc is larger in the wiper operating state.
In step S40, the calculated subtraction amount PGcmc is stored.

Note that the subtraction amount PGcmc set in step S40 may be set in consideration of the outside air temperature. In this case, an outside air temperature detection unit (not shown) such as a temperature sensor (not shown) is provided, and in step S37, the subtraction amount PGcmc is set to a larger value as the outside air temperature detected by the outside air temperature detection unit is lower.
In step S41, a brake energy evaluation index value Ecbr is calculated. That is, if it is a brake operating state, the brake energy evaluation index value Ecbr is calculated by the following equation (10) using the brake pressure value Pcmc calculated in step S36. The brake energy evaluation index value Ecbr is calculated by the following equation (11) using the subtraction amount PGcmc calculated in step (1).
Ecbr = Ecbr + Pcmc (10)
Ecbr = Ecbr-PGcmc (11)

  As a result, in the brake operating state, the brake energy evaluation index value Ecbr increases by the brake pressure value Pcmc according to the equation (10). Further, as described in step S36, the brake pressure value Pcmc is a value other than immediately after the engine is started, and becomes a larger value as the brake pressure detection value Psmc becomes larger. Therefore, the brake energy evaluation index value Ecbr Also, it becomes larger if it is other than immediately after the engine is started, and becomes larger as the brake pressure detection value Psmc becomes larger. On the other hand, since the brake pressure value Pcmc is smaller than that immediately after the engine is started, the brake energy evaluation index value Ecbr is less increased immediately after the engine is started.

If the brake is not in operation, the brake energy evaluation index value Ecbr is reduced by the subtraction amount PGcmc according to the equation (11). Further, as described in step S40, the subtraction amount PGcmc becomes a large value if the wiper is in an operating state, and becomes a larger value as the host vehicle speed V is increased. Therefore, the brake energy evaluation index value Ecbr is set in the wiper operating state. If the vehicle speed V increases, the vehicle speed V decreases.
Further, since the process shown in FIG. 2 is performed at a predetermined sampling time, the brake cold time adjustment gain Kcbr is set to the brake pressure detection value Psmc whether or not it is immediately after starting the engine during the brake operation state. Accordingly, it increases with the passage of time, while it changes in the opposite direction to the brake operation state according to the wiper operation state or the own vehicle speed during the brake non-operation state, that is, decreases with the passage of time. I will do it.

For this reason, the brake energy evaluation index value Ecbr indicates the amount of heat storage energy by the brake. If this value is large, the heat storage energy is large at that time, that is, the brake is warmed. Yes, if this value is small, it indicates that the heat storage energy is small at that time, that is, the brake is cold.
In this process, the brake energy evaluation index value Ecbr, which is a temperature evaluation value, is changed according to the history of the brake fluid pressure value (brake pressure detection value Psmc), and the brake energy evaluation index value that changes in this way. This is equivalent to correcting Ecbr according to the vehicle state and the state of the surrounding environment of the host vehicle.
Further, as described above, the reason why the wiper operating state is viewed in order to determine the subtraction amount PGcmc, that is, to determine the brake energy evaluation index value Ecbr, is to predict the weather state. That is, if the wiper is operating, it is raining, snowing, etc. In this case, since the brake is cooled, the wiper operating flag Fwp is set (Fwp = ON). The subtraction amount PGsmc is set to a large value (see the above equation (8)).

Subsequently, in step S42, a brake cold time adjustment gain Kcbr is calculated based on the brake energy evaluation index value Ecbr calculated in step S41. FIG. 11 shows the relationship between the brake energy evaluation index value Ecbr and the brake cold time adjustment gain Kcbr. As shown in FIG. 11, in a region where the brake energy evaluation index value Ecbr is small, the brake energy evaluation index value Ecbr increases when the brake energy evaluation index value Ecbr takes a certain value. Thus, the brake cold time adjustment gain Kcbr decreases, and the brake cold time adjustment gain Kcbr becomes a constant value of 1 in a region where the brake energy evaluation index value Ecbr is larger than a certain value.
That is, if the heat storage energy is large and the brake is warm, the brake energy evaluation index value Ecbr becomes a small value, so the brake cold time adjustment gain Kcbr becomes a small value, the heat storage energy is small, and the brake If the vehicle is in a cold state, the brake energy evaluation index value Ecbr becomes a large value, so that the brake cold time adjustment gain Kcbr becomes a large value.

  Subsequently, in step S43, a new target yaw moment Ms is calculated by multiplying the brake cold time adjustment gain Kcbr calculated in step S42 by the target yaw moment Ms calculated in step S11 (Ms = Ms × Kcbr). ). That is, the target yaw moment Ms is corrected based on the brake cold time adjustment gain Kcbr. Thus, when the heat storage energy is large and the brake is warm, the brake cold time adjustment gain Kcbr is set to 1 or a value close thereto, so that the target yaw moment Ms is not corrected. Or when the correction is made with a small correction amount, the heat storage energy is small, and the brake is cold, the brake cold time adjustment gain Kcbr is set to a large value, so the target yaw moment Ms is It is corrected to be a large value.

As described above, the brake cold correction process is performed in step S12.
Subsequently, in step S13, an upper limit value Ms2 of the target yaw moment is set. Specifically, the upper limit value Ms2 is set to be larger during emergency braking than during normal braking. FIG. 12 shows an example of the characteristic of the upper limit value Ms2. As shown in FIG. 12, the upper limit value Ms2 is different between normal braking and emergency braking, and is set based on the brake determination flag Fem set in step S7. That is, when the brake determination flag Fem is set (Fem = 1 (Fem = ON)), the emergency brake value is set to a large value as the upper limit value Ms2, and the brake determination flag Fem is reset (Fem = 0). (Fem = OFF)), a small value is set as the normal brake value in the upper limit value Ms2.

Subsequently, in step S14, target braking hydraulic pressure differences ΔPsf and ΔPsr between the left and right wheels are calculated for the front and rear wheels.
(1) Specifically, when the departure determination flag Fout is reset (Fout = OFF), the target braking hydraulic pressure differences ΔPsf and ΔPsr between the left and right wheels are set to 0 for the front and rear wheels.
(2) On the other hand, when the departure determination flag Fout is set (Fout = ON), the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated based on the target yaw moment Ms. Specifically, the target braking hydraulic pressure differences ΔPsf and ΔPsr are calculated by the following equations (12) to (15).

When | Ms | <Ms1 ΔPsf = 0 (12)
ΔPsr = 2 · Kbr · Ms / T (13)
When | Ms | ≧ Ms1 ΔPsf = 2 · Kbf · (| Ms | −Ms1) / T (14)
ΔPsr = 2 · Kbr · | Ms1 | / T (15)
Here, Ms1 represents a setting threshold value. T represents a tread. The tread T is set to the same value before and after for the sake of 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. That is, when the target yaw moment Ms is less than the setting threshold value Ms1, the front wheel target braking hydraulic pressure difference ΔPsf is set to 0, a predetermined value is given to the rear wheel target braking hydraulic pressure difference ΔPsr, and a braking force difference is generated between the left and right rear wheels. Further, when the target yaw moment Ms is equal to or larger than the setting threshold value Ms1, a predetermined value is given to each target braking hydraulic pressure difference ΔPsr, ΔPsr, and a braking force difference is generated between the front, rear, left and right wheels.

(3) When the absolute value | Ms | of the target yaw moment Ms is equal to or larger than the upper limit value Ms2 (> Ms1) set in step S13 (| Ms | ≧ Ms2), the following expressions (16) and (17) To calculate the target braking hydraulic pressure difference ΔPsf, ΔPsr.
ΔPsf = 2 · Kbf · (Ms2−Ms1) / T (16)
ΔPsr = 2 · Kbr · Ms1 / T (17)
Thus, the target yaw moment Ms is limited so as not to exceed the upper limit value Ms2. As a result, the target yaw moment Ms becomes too large, and the target yaw moment is applied to the vehicle as lane departure prevention control, thereby preventing the driver from feeling uncomfortable.

Further, by limiting the target yaw moment Ms by the upper limit value Ms2 in this way, while preventing the driver from feeling uncomfortable, the upper limit value Ms2 is increased during emergency braking (see step S13). ) The target yaw moment Ms is larger than that in the normal state so that lane departure can be reliably prevented even in an emergency.
Subsequently, in step S15, a target deceleration amount for deceleration control for preventing lane departure is calculated. Specifically, when the emergency brake determination flag Fem is set in step S7 (Fbem = ON), the target braking hydraulic pressure Pg as the target deceleration amount is set to 0, assuming that the deceleration control for preventing lane departure is not performed. To do.
When the departure determination flag Fout is set (Fout = ON), the target braking hydraulic pressure Pg is set. In this case, the estimated lateral displacement Xs calculated in step S3 is the departure used in step S9. with-tendency threshold value X _L and deceleration control determination threshold value Xβ and gain Kv set at step S10, and calculates the target brake hydraulic pressure Pg by the following equation (18).

Pg = −Kv · Kv3 · (Xs−X _L −Xβ) (18)
Here, Kv3 is a predetermined gain.
On the other hand, when the departure determination flag Fout is reset (Fout = OFF), the target braking hydraulic pressure Pg is set to 0, assuming that the deceleration control for preventing lane departure is not performed.
Subsequently, in step S16, a target brake hydraulic pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated.

(1) Specifically, when the departure determination flag Fout is reset (Fout = OFF), the following equations (19) and (20) are obtained based on the master cylinder hydraulic pressure Pm read in step S1. As shown, a target brake fluid pressure Psi (i = fl, fr, rl, rr) for each wheel is set.
Psfl = Psfr = Pmf (19)
Psrl = Psrr = Pmr (20)
Here, Pmf is the brake fluid pressure (Pm) for the front wheels. Further, Pmr is a brake fluid pressure for the rear wheels, and is a value calculated based on the brake fluid pressure Pmf for the front wheels with respect to the master cylinder fluid pressure Pm in consideration of the front-rear distribution.
As shown in the equations (19) and (20), when the departure determination flag Fout is reset (Fout = OFF), the target brake hydraulic pressures Psfl and Psfr for the front left and right wheels are both the master cylinder hydraulic pressure Pm ( Pmf), the rear left and right wheel target braking fluid pressures Psrl and Psrr are both the rear wheel braking fluid pressure Pmr.

(2) On the other hand, although the departure determination flag Fout is set (Fout = ON), the deceleration control operation determination flag Fgs is reset (Fgs = OFF), and the calculation is performed in step S11 (or step S12). When the target yaw moment Ms is a negative value (when the host vehicle is likely to deviate in the left direction), the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (21). To do.
Psfl = Pm
Psfr = Pm + ΔPsf
Psrl = Pmr
Psrr = Pmr + ΔPsr
... (21)

(3) Although the departure determination flag Fout is set (Fout = ON), the deceleration control operation determination flag Fgs is reset (Fgs = OFF), and the calculation is performed in step S11 (or step S12). When the target yaw moment Ms is a positive value (when the host vehicle is likely to deviate in the right direction), the target braking fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is calculated by the following equation (22). To do.
Psfl = Pm + ΔPsf
Psfr = Pm
Psrl = Pmr + ΔPsr
Psrr = Pmr
(22)

(4) Further, the departure determination flag Fout and the deceleration control operation determination flag Fgs are set (Fout = ON and Fgs = ON), and the target yaw moment Ms calculated in step S11 (or step S12) is a negative value. (When the host vehicle is likely to depart from the lane in the left direction), using the target braking fluid pressure Pg calculated in step S15, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pm + Kg · Pg
Psfr = Pm + Kg · Pg + ΔPsf
Psrl = Pmr + Kg · Pg
Psrr = Pmr + Kg · Pg + ΔPsr
(23)

(5) Further, the departure determination flag Fout and the deceleration control operation determination flag Fgs are set (Fout = ON and Fgs = ON), and the target yaw moment Ms calculated in step S11 (or step S12) is a positive value. (When the host vehicle is likely to depart from the lane in the right direction), using the target braking fluid pressure Pg calculated in step S15, the target braking fluid pressure Psi (i = fl, fr, rl, rr) is calculated.
Psfl = Pm + Kg · Pg + ΔPsf
Psfr = Pm + Kg · Pg
Psrl = Pmr + Kg · Pg + ΔPsr
Psrr = Pmr + Kg · Pg
... (24)

Subsequently, in step S17, a target driving force of the driving wheel is calculated. Specifically, when the departure determination flag Fout is set in step S8 (Fout = ON), that is, when lane departure prevention control is performed, the engine output is output even when the driver performs an accelerator operation. Set the target driving force to be reduced. For example, when the departure determination flag Fout is set, the target braking hydraulic pressure differences ΔPsf and ΔPsr of the front and rear wheels and the target deceleration amount Pg of all the wheels are calculated from the target driving force corresponding to the accelerator opening θt read in step S1. A value corresponding to the sum of the values is subtracted to obtain a corrected target driving force.
Here, the target driving force according to the accelerator opening degree θt is a driving torque that the host vehicle accelerates according to the accelerator opening degree θt, and the target braking hydraulic pressure differences ΔPsf, ΔPsr between the front and rear wheels and the target deceleration amounts of all the wheels. The value corresponding to the sum of Pg is a value corresponding to the braking torque generated by the sum of the target braking hydraulic pressure differences ΔPsf, ΔPsr of the front and rear wheels and the target deceleration amount Pg of all the wheels. As a result, when the departure determination flag Fout is set, the engine torque is reduced by an amount corresponding to the braking torque.

When the departure determination flag Fout is reset (Fout = OFF), the target driving force is a driving torque that the host vehicle accelerates according to the accelerator opening θt.
In step S18, a braking / driving force signal is output. Specifically, the target braking fluid pressure Psi (i = fl, fr, rl, rr) calculated for each wheel calculated in step S16 is output to the braking fluid pressure control unit 7, and the target driving force calculated in step S17. Is output to the drive torque control unit 12.
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 (deviation estimated value) Xs is calculated (step S3), a vehicle stability determination flag Fcs is set from the turning state of the host vehicle (step S4), and the lane change is performed. The intention determination flag _FLC is set (step S5). Then, based on the estimated lateral displacement (departure estimate value) comparison result between the Xs and departure-tendency threshold value X _L, an alarm output (step S6).
Subsequently, an emergency brake determination flag Fem is set based on the driver's brake operation state (step S7).

Then, based on the estimated lateral displacement (deviation estimate) Xs and deviation tendency compared with determining threshold value X _L results, determines departure tendency with respect to the own vehicle travel lane, the presence or absence of the departure tendency and depending on lane change intention determination flag F _LC, it sets the departure flag Fout (step S8). In this case, in consideration of the vehicle stability determination flag Fcs and lane change intention determination flag F _LC, it sets the departure flag Fout.
Subsequently, based on the comparison result between the subtraction value (| Xs | −X _L ) obtained by subtracting the departure tendency determination threshold value X _L from the estimated lateral displacement Xs and the deceleration control determination threshold value Xβ, deceleration is performed. A control operation determination flag Fgs is set (step S9).

Subsequently, various gains used for calculation of lane departure prevention control are set (step S10), and the target yaw moment Ms is calculated using the set gain and the like (step S11).
Subsequently, as a brake cold correction process, a brake energy evaluation index value Ecbr indicating the so-called heat storage energy of the brake is calculated, and a brake cold time adjustment gain Kcbr is calculated based on the brake energy evaluation index value Ecbr. Then, the target yaw moment Ms is corrected based on the brake cold time adjustment gain Kcbr (step S12). Then, an upper limit value Ms2 of the target yaw moment Ms is set based on the emergency brake determination flag Fem (step S13).

  Subsequently, based on the state of the departure determination flag Fout and the upper limit value Ms2, target brake hydraulic pressure differences ΔPsf and ΔPsr for the front and rear left and right wheels are calculated (step S14), and the state of the emergency brake determination flag Fem and the departure determination flag Fout. Based on the state, the target braking hydraulic pressure Pg of the lane departure prevention deceleration control is calculated (step S15). Then, based on the state of the departure determination flag Fout, the state of the deceleration control operation determination flag Fgs, the target braking fluid pressure difference ΔPsf, ΔPsr, and the target braking fluid pressure Pg, the target braking fluid pressure Psi (i = fl, fr) of each wheel. , Rl, rr) is calculated (step S16). On the other hand, the target driving force of the driving wheel is calculated based on the state of the departure determination flag Fout (step S17). Then, the target brake fluid pressure Psi (i = fl, fr, rl, rr) of each wheel is output to the brake fluid pressure control unit 7, and the target drive force is output to the drive torque control unit 12 (step S18).

According to such a process, for example, when the steering input is small, a yaw moment is generated in the own vehicle to prevent the own vehicle from departing from the lane, and the traveling speed of the vehicle is reduced by the braking force at that time. Therefore, lane departure can be prevented more safely.
Further, while the lane departure prevention control is being performed, the output torque of the engine is reduced and the traveling speed of the host vehicle is decelerated, so that the lane departure can be prevented more safely.
Further, calculating the departure flag Fout is set based on the deviation estimate departure-tendency threshold value X _L was obtained by subtracting the subtraction value from Xs (Xs-X _L), the target brake hydraulic pressure Pg When the subtraction value (| Xs | −X _L ) becomes equal to or greater than the deceleration control determination threshold value Xβ, it is determined that the host vehicle needs to be decelerated. The deceleration control operation determination flag Fgs is set, and the braking force of all the wheels is controlled so that the target braking hydraulic pressure Pg is achieved by the deceleration control for lane departure prevention.

  Accordingly, as shown in FIG. 13A, when a steep curve appears in front of the host vehicle 100 and the deviation estimated value (future estimated lateral displacement) Xs becomes large, the lane deviation preventing deceleration control is performed. The host vehicle 100 is decelerated, and as a result, the estimated departure value Xs is reduced. As a result, the yaw moment applied to the host vehicle as the lane departure prevention control is reduced, so that the lane departure prevention control does not give the passenger a sense of incongruity. Just do it.

Note that, as shown in FIG. 13B, when the own vehicle 100 does not decelerate even though a steep curve appears in front of the own vehicle and the deviation estimated value Xs is increased, the lane Since the yaw moment that is given to the host vehicle as the departure prevention control increases, the lane departure prevention control gives a sense of incongruity to the occupant.
Further, when the brake is in a cold state, the target yaw moment Ms is corrected so as to increase, and a large yaw moment is applied to the vehicle as lane departure prevention control. As a result, even if the brake is cold and ineffective, that is, even if the brake is at a temperature lower than the temperature at which the brake can operate optimally, the vehicle will not be affected. Can be reliably prevented.

Next, effects of the embodiment will be described.
As described above, when the brake is in a cold state, the target yaw moment Ms is corrected so as to increase, so that the brake is cold and ineffective (if the brake is ineffective) Even when expected, it is possible to reliably prevent the vehicle from deviating from the lane without being affected by the influence. That is, the temperature dependence of the braking force generating means is compensated to reliably prevent the host vehicle from departing from the lane.
As described above, the target yaw moment Ms increases as the brake energy evaluation index value Ecbr decreases (as the rake cold time adjustment gain Kcbr increases). As a result, the target yaw moment Ms increases as the expected braking effectiveness deteriorates, so that it is possible to more reliably prevent the host vehicle from deviating from the lane.

Also, the energy evaluation index value Ecbr for evaluating the brake temperature is obtained based on the detected brake pressure value, and the detected brake pressure value is not obtained by a special configuration. Can be evaluated.
Further, as described above, the energy evaluation index value Ecbr is obtained based on the vehicle state such as the engine start state and the own vehicle speed, and the surrounding environment state such as the weather state and the outside temperature of the own vehicle (correction). Therefore, the brake temperature can be evaluated more accurately.
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, as described as the process of step S12, the control amount of the lane departure prevention control is changed based on the brake cold time adjustment gain Kcbr, that is, the brake energy evaluation index value Ecbr. The target yaw moment Ms is corrected. However, it is not limited to this. That is, the start amount of the lane departure prevention control may be advanced by changing the control amount of the lane departure prevention control. In this case, for example, as shown in FIG. 14, the vehicle head time Tt for calculating the forward gaze distance used for calculating the estimated lateral displacement Xs by the above equation (2) increases as the brake energy evaluation index value Ecbr decreases. To do. As a result, the estimated lateral displacement Xs increases as the vehicle head time Tt increases, so that it is easy to determine that there is a tendency to deviate from the lane. That is, the start timing of the lane departure prevention control is advanced. Further, as shown in FIG. 15, the departure-tendency threshold value X _L used for the determination of the lane departure tendency, the more braking energy evaluation index value Ecbr decreases, to decrease. Thus, according to the process of the step S8, as the departure-tendency threshold value X _L is reduced, because more likely to be determined that there is a lane departure tendency, the more braking energy evaluation index value Ecbr decreases, there lane departure tendency That is, the start timing of the lane departure prevention control is advanced.

As a result, when the brake is in a cold state, the start timing of the lane departure prevention control is advanced, so even if the brake is cold and ineffective, the vehicle is not affected by the lane. It is possible to reliably prevent deviation.
Further, the temperature of the brake shoe may be directly measured by the temperature detection means, and the brake energy evaluation index value Ecbr or the brake cold time adjustment gain Kcbr may be set based on the measured value. Accordingly, the target yaw moment Ms and the start timing of the lane departure prevention control can be corrected based on more accurate temperature evaluation.
In the embodiment, the brake energy evaluation index value Ecbr is set based on the history of the brake pressure detection value Psmc (brake hydraulic pressure value), the vehicle state and the weather state, and the state of the surrounding environment of the host vehicle. However, it is not limited to this. That is, the brake energy evaluation index value Ecbr may be set based only on the history of at least the brake pressure detection value Psmc (brake hydraulic pressure value).

  In the embodiment, the case where the brake structure is constituted by a drum brake structure including a brake shoe and a wheel cylinder has been described. However, it is not limited to this. That is, the brake structure may be constituted by a disc brake structure including a brake pad and a caliper. In this case, the brake energy evaluation index value Ecbr evaluates the temperature of the brake pad, for example.

  In the description of the embodiment, the process of step S8 of the braking / driving force control unit 8 realizes a lane departure tendency determination means for determining a departure tendency of the host vehicle with respect to the traveling lane, and the wheel cylinders 6FL to 6RR are realized. And a brake structure including a brake pad realizes a braking force generating means for generating a braking force on the wheel when the lane departure tendency determining means determines that the vehicle has a lane departure tendency. The process of calculating the brake energy evaluation index value Ecbr in step S12 realizes a temperature detection means for detecting the temperature of the braking force generation means, and the brake energy evaluation index value Ecbr (in step S12 of the braking / driving force control unit 8). Correction process (step of target yaw moment Ms) using temperature evaluation value 43), the temperature of the temperature detecting unit detects if a low temperature is realized a control amount changing means for changing the control amount of the lane departure prevention control.

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 (9)

When the host vehicle tends to deviate from the driving lane, the braking force generating means generates a braking force difference between the left and right wheels, thereby giving yaw moment to the host vehicle and causing the host vehicle to deviate from the driving lane. In a lane departure prevention device for performing lane departure prevention control for preventing
When the temperature of the braking force generating means is lower than the temperature at which the braking force generating means can operate optimally, the control amount of the lane departure prevention control is increased by increasing the braking force difference between the left and right wheels. A lane departure prevention device, characterized in that the lane departure prevention device is changed to a direction to perform. When the host vehicle tends to deviate from the driving lane, the braking force generating means generates a braking force difference between the left and right wheels, thereby giving yaw moment to the host vehicle and causing the host vehicle to deviate from the driving lane. In a lane departure prevention device for performing lane departure prevention control for preventing
Temperature detecting means for detecting the temperature of the braking force generating means;
Control amount changing means for changing the control amount of the lane departure prevention control in the direction of increasing the braking force difference by increasing the braking force difference between the left and right wheels when the temperature detected by the temperature detecting means is low; ,
A lane departure prevention apparatus comprising: The lane departure prevention apparatus according to claim 1 or 2, wherein the lower the temperature of the braking force generation means, the earlier the determination timing when the host vehicle tends to depart. 3. The lane departure prevention apparatus according to claim 1, wherein the control amount changing unit increases the change amount of the control amount as the temperature is lower. Temperature detecting means for detecting the temperature of the braking force generating means;
Said temperature detecting means, based on the history of the brake fluid pressure value, the lane departure prevention apparatus according to any one of claims 2 to 4, characterized in that predicting detecting the temperature of said braking force generating means. Temperature detecting means for detecting the temperature of the braking force generating means;
Said temperature detecting means, based on at least one state of the state of the surrounding environment of the vehicle conditions and vehicle, any claim 2 to 5, wherein the predicting detecting the temperature of said braking force generating means The lane departure prevention apparatus according to claim 1. Temperature detecting means for detecting the temperature of the braking force generating means;
The temperature detection means has a temperature evaluation value for evaluating the temperature of the braking force generation means, and the control amount changing means changes the control amount of the lane departure prevention control based on the temperature evaluation value. The temperature detecting means changes the temperature evaluation value according to the history of the brake fluid pressure value, and according to at least one of the vehicle state and the surrounding environment of the host vehicle, The lane departure prevention apparatus according to any one of claims 2 to 6 , wherein the temperature evaluation value is corrected. The vehicle state is at least one of an engine water temperature state and a vehicle speed state, and the surrounding environment of the host vehicle is at least one of a weather state and an outside air temperature state of the host vehicle. The lane departure prevention device according to claim 6 or 7 , wherein the lane departure prevention device is a lane departure prevention device. Temperature detecting means for detecting the temperature of the braking force generating means;
The lane departure prevention apparatus according to any one of claims 2 to 5 , wherein the temperature detection unit detects a temperature of a brake pad as a temperature of the braking force generation unit.

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