JP4385751B2 - 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 during traveling.

As a conventional lane departure prevention device, the lane departure from the traveling lane of the host vehicle is judged, and the left and right wheels are controlled according to the estimated amount of departure from the future lane calculated based on the traveling state of the host vehicle. It is known to avoid lane departure by braking control that combines yaw control that generates a yaw moment in the vehicle by giving a power difference and deceleration control that applies braking force to each wheel so that the host vehicle decelerates. (For example, refer to Patent Document 1).
Japanese Unexamined Patent Publication No. 2003-112540 (page 7, FIG. 2)

However, in the above conventional lane departure prevention device, the yaw moment and deceleration amount to the vehicle are determined according to the estimated departure amount from the lane in the future, so when performing braking control including deceleration control. In addition, when the driver performs a brake operation, there is a case where the driver decelerates more than necessary, and there is an unsolved problem that the driver feels uncomfortable.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and even when the driver is performing a brake operation at the time of departure from the lane, the driver does not feel uncomfortable. An object of the present invention is to provide a lane departure prevention device capable of performing departure avoidance control.

In order to achieve the above object, a lane departure prevention apparatus according to the present invention estimates and detects a departure estimated value that is a lateral displacement in a traveling lane after a predetermined time of the host vehicle by a traveling state detecting means, and detects a braking operation amount. detecting the amount of braking operation by the driver of the brake operation by the detection means, on the basis of the traveling state detected deviation estimate by the detection means, to determine that in deviation judgment means the vehicle is in a deviation tendency from the traffic lane . When the departure determining means determines that the host vehicle tends to depart from the traveling lane, the yaw control amount calculating means calculates the traveling lane of the own vehicle based on the estimated deviation detected by the traveling state detecting means. The first braking force control amount of each wheel is calculated so that a larger yaw moment is generated as the deviation estimated value is larger in a direction to avoid deviation from the vehicle . When the estimated departure value detected by the traveling state detection means is greater than or equal to a predetermined value, a traveling state deceleration amount that is a deceleration amount corresponding to the departure estimated value is calculated, and a braking control amount calculation means Compares the calculated traveling state deceleration amount with the vehicle deceleration amount corresponding to the braking operation amount detected by the braking operation amount detection means, and a braking force corresponding to the larger deceleration amount is generated in the host vehicle. Thus, the second braking force control amount of each wheel is calculated . Then, the braking force control means controls the braking force of each wheel according to the first and second braking force control amounts calculated by the yaw control amount calculation means and the braking control amount calculation means.

  According to the present invention, when the host vehicle tends to deviate from the driving lane, the deviation prevention control is performed by combining the yaw control and the deceleration control, and the deceleration operation amount by the driver's brake operation is set in the deceleration amount of the deceleration control. Since deceleration is taken into consideration, it is possible to suppress the amount of deceleration for reducing the passenger's uncomfortable feeling caused by the yaw moment applied to the vehicle to the minimum necessary, and to further reduce the uncomfortable feeling to the driver and perform departure prevention control In addition, the durability of brake pads and the like can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention. This vehicle is a rear wheel drive vehicle equipped with an automatic transmission and a conventional differential gear, and the braking device can control the braking force (braking fluid pressure) of the left and right wheels independently of the front and rear wheels.
In the figure, reference numeral 1 is a brake pedal, 2 is a booster, 3 is a master cylinder, 4 is a reservoir, 9 is an engine, and 10 is an automatic transmission. Normally, the master pedal depends on the amount of depression of the brake pedal 1 by the driver. The brake fluid pressure boosted by the cylinder 3 is supplied to the wheel cylinders 6FL to 6RR of the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR. Further, a braking fluid pressure control circuit 7 is interposed between the master cylinder 3 and each wheel cylinder 6FL-6RR. The braking fluid pressure control circuit 7 includes a braking fluid for each wheel cylinder 6FL-6RR. It is also possible to control the pressure individually.

  The brake fluid pressure control circuit 7 uses a brake fluid pressure control circuit used for antiskid control or traction control, for example. In this embodiment, the brake fluid pressure of each wheel cylinder 6FL-6RR is independently set. It is configured so that the pressure can be increased or decreased. The brake fluid pressure control circuit 7 controls the brake fluid pressures of the wheel cylinders 6FL to 6RR in accordance with a brake fluid pressure command value from a control unit 8 described later.

  In addition, this vehicle includes a CCD camera 13 and a camera controller 14 as an external recognition sensor for detecting the position of the host vehicle in the traveling lane for determining the traveling lane departure prevention of the host vehicle. The camera controller 14 detects a lane marker by detecting a lane marker such as a road marking line from a captured image in front of the host vehicle captured by the CCD camera 13, and further detects the yaw angle Φ of the host vehicle with respect to the lane of travel, The lateral displacement X from the center of the lane, the curvature β of the traveling lane, the lane width L, and the like can be calculated, and these calculation signals are output to the control unit 8.

Further, in this vehicle, a master cylinder pressure sensor 16 as a braking operation amount detecting means for detecting an output pressure of the master cylinder 3, that is, a so-called master cylinder pressure Pm, and a steering angle sensor 20 for detecting a steering angle δ of the steering wheel 19 are provided. , Wheel speed sensors 21FL to 21RR for detecting the rotational speeds of the wheels 5FL to 5RR, that is, so-called wheel speeds Vw _j (j = FL to RR), direction indicating switches 22 for detecting direction indicating operations by the direction indicators, and driver braking A stroke sensor 23 that detects an operation amount (stroke amount) Ls is provided, and detection signals thereof are output to the control unit 8.

If the detected vehicle traveling state data has left and right directions, the left direction is the positive direction. That is, the yaw angle Φ becomes a positive value when turning left, and the lateral displacement X becomes a positive value when it is shifted to the left from the center of the traveling lane.
Further, a warning device 24 is provided in front of the driver's seat to present a warning to the driver in response to an alarm signal AL from the control unit 8 when a deviation from the driving lane is detected. Built-in speaker for generating buzzer sound.

Next, the lane departure prevention control process performed by the control unit 8 will be described with reference to the flowchart of FIG. This lane departure prevention control process is executed by, for example, a timer interrupt process every 10 msec.
In this lane departure prevention control process, first, in step S1, various data from the respective sensors and controllers are read. Specifically, each wheel speed Vw _j detected by each sensor, master cylinder pressure Pm, steering angle δ, direction indicating switch signal WS, stroke amount Ls, vehicle yaw angle Φ with respect to the travel lane from the camera controller 14, The lateral displacement X from the center of the travel lane, the curvature β of the travel lane, and the travel lane width L are read.

Next, the process proceeds to step S2, and the vehicle speed V of the host vehicle is calculated from the average value of the front left and right wheel speeds Vw _FL and Vw _FR which are non-driven wheels among the wheel speeds Vw _{FL to} Vw _RR read in step S1. calculate.
V = (Vw _FL + Vw _FR ) / 2 (1)
Next, in step S3, as shown in FIG. 3, an estimated lateral displacement, that is, an estimated deviation value Xs after a predetermined time Tt [sec] is calculated. Specifically, based on the lateral displacement X from the center of the travel lane read in step S1 and the lateral displacement speed dX calculated by differentiating the lateral displacement X, the deviation estimated value according to the following equation (2): Xs is calculated, and the process proceeds to step S4.
Xs = dX × Tt + X (2)

Further, the deviation estimated value Xs is the vehicle yaw angle Φ with respect to the traveling lane of the own vehicle read in step S1, the lateral displacement X from the center of the traveling lane, the curvature β of the traveling lane, and the own vehicle calculated in step S2. Based on the vehicle speed V, it may be calculated according to the following equation (3).
Xs = Tt × V × (Φ + Tt × V × β) + X (3)
It should be noted that the deviation estimated value Xs becomes a positive value when deviating leftward.
The deviation estimated value Xs is compared with the position of the boundary line of the center of gravity of the vehicle in the travel lane, that is, the departure boundary line _XL, and the lane departure of the host vehicle is determined. First, in step S4, a departure boundary line _XL is calculated. The departure boundary line _XL is calculated based on the following equation (4) based on the travel lane width L and the width H of the host vehicle. The right side is a positive value.
X _L = ± (L−H) / 2 (4)

Next, in step S5, it is determined whether or not the absolute value | Xs | of the deviation estimated value Xs is equal to or larger than the absolute value | X _L | of the deviation boundary line X _L , and | Xs | <| X _L |. Sometimes the process proceeds to step S6, the departure determination flag _Fout is reset to “0” which means that the host vehicle does not tend to deviate, and the process proceeds to step S11 described later.
Further, when | Xs | ≧ | X _L |, the routine proceeds to step S7, the departure determination flag _Fout is set to “1” which means that the host vehicle tends to depart, and the routine proceeds to step S8. Whether the estimated deviation value Xs is positive or negative is determined. When Xs ≧ 0, it is determined that the deviation is to the left, and the process proceeds to step S9. The deviation direction flag _Dout is set to “1”, and then the process proceeds to step S11 described later. On the other hand, when Xs <0, it is determined that the deviation is to the right, and the process proceeds to step S10. The deviation direction flag _Dout is set to “2”, and then the process proceeds to step S11.

Next, the driver's intention to change the lane is determined based on the direction indication switch and the steering angle. First, in step S11, it is determined whether or not the direction indicating switch 22 is in an on state. If the direction indicating switch 22 is in an on state, the process proceeds to step S12 and is determined by the operation direction of the direction indicating switch and the departure direction flag _Dout. It is determined whether or not the departure direction matches, and when both directions match, it is determined that the lane has been changed and the process proceeds to step S13, and the departure determination flag _Fout is reset to “0”. The process proceeds to step S15 described later. On the other hand, when both directions do not coincide with each other, it is determined that the lane is not changed, and the process directly proceeds to step S15 described later.

If the result of determination in step S11 is that the direction indicating switch 22 is in the OFF state, the process proceeds to step S14, where the steering angle δ is equal to or larger than the preset steering angle setting value δ _S and the steering angle change amount Δδ is predetermined. It is determined whether or not the set change amount setting value Δδ _S or more. If δ ≧ δ _S and Δδ ≧ Δδ _S, it is determined that the driver is willing to change the lane, and the process proceeds to step S13. Transition. On the other hand, when δ <δ _S or Δδ <Δδ _S, it is determined that the driver is not willing to change lanes, and the routine proceeds to step S15.

Incidentally, here, the driver's intention to change the lane is determined based on the steering angle δ and the steering angle change amount Δδ. However, the present invention is not limited to this. For example, the determination is made by detecting the steering torque. You may do it.
In step S15, based on the lane curvature β and the vehicle speed V, a parameter Xa that is a threshold for determining the necessity of deceleration control is calculated with reference to the parameter calculation map shown in FIG. The parameter calculation map is set so that the parameter Xa is calculated smaller as the curvature β is larger and the vehicle speed V is faster.

Next, in step S16, whether or not the value | Xs | − | X _L | obtained by subtracting the absolute value of the deviation boundary line X _L from the absolute value of the deviation estimated value Xs is equal to or larger than the parameter Xa calculated in step S15. When | Xs | − | X _L | ≧ Xa, that is, when the deviation estimated value Xs deviates from the deviation boundary line X _L by Xa or more, it is determined that deceleration control of the host vehicle is required. The process proceeds to step S17, the deceleration control operation flag Fgs is set to “1”, and then the process proceeds to step S19 described later. If the determination result in step S16 is | Xs | − | X _L | <Xa, the process proceeds to step S18, the deceleration control operation flag Fgs is set to “0”, and then the process proceeds to step S19.

In order to set the deceleration control operation flag Fgs in this way, for example, when the curve of the traveling lane ahead of the host vehicle is gentle and the estimated departure value Xs is small, Fgs = 0, so that the host vehicle is decelerated. There is no end to it, and the passengers do not have to feel uncomfortable.
Further, since the parameter Xa is set to decrease as the curvature β of the traveling lane of the host vehicle increases, for example, if a steep curve appears in front of the host vehicle, | Xs | − | X _L | ≧ Xa Since the deceleration control operation flag Fgs is set to “1”, the host vehicle is decelerated and an increase in the estimated departure value Xs is suppressed.

Further, since the parameter Xa is set so as to decrease as the host vehicle speed V increases, for example, when the host vehicle is traveling at high speed, | Xs | − | X _L | ≧ Xa and deceleration control operation is performed. Since the flag Fgs is set to “1”, the host vehicle is decelerated and an increase in the estimated departure value Xs is suppressed.
In step S19, it is determined whether or not the departure determination flag F _out is set to “1” which means that the own vehicle has a departure tendency. If F _out = 1, the process proceeds to step S20. Then, the alarm signal AL is output to the alarm device 24 to activate the alarm, and then the process proceeds to step S21.

In step S21, the calculation of the following equation (5) is performed to calculate the target yaw moment Ms, and then the process proceeds to step S24 described later.
Ms = Ks × (Xs−X _L ) (5)
Here, Ks is a positive value that varies according to the vehicle speed V, and is calculated based on the vehicle speed V with reference to the gain calculation map shown in FIG.
When the determination result in step S19 is F _out = 0, the process proceeds to step S22, the output of the alarm signal AL is stopped, then the process proceeds to step S23, and the target yaw moment Ms is expressed by the following equation (6). After setting to 0 (zero) based on the above, the process proceeds to step S24.
Ms = 0 (6)

In step S24, a target brake fluid pressure calculation process is performed to calculate a target brake fluid pressure Ps _i (i = FL to RR) for each wheel according to the target yaw moment Ms and the master cylinder fluid pressure Pm.
Then, the process proceeds to step S25, to return from the output of the target brake hydraulic pressures Ps _FL ~Ps _RR calculated at step S24 to the brake hydraulic control circuit 7 to end the timer interrupt process to a predetermined main program .
In the step S24, it determines whether or not subjected to target brake hydraulic pressure calculation processing shown in FIG. 6, first departure determination flag F _out in step S31 is reset to "0".

When the determination result in step S31 is F _out = 0, the process proceeds to step S32, and the target braking hydraulic pressure Ps _FL of the front left wheel and the target braking hydraulic pressure Ps of the front right wheel as shown in the following equation (7). sets the _FR to 1/2 of the front wheel master cylinder pressure Pmf considering the rear distribution from the master cylinder pressure Pm, the following (8) of the target brake hydraulic pressures Ps _RL and rear right wheel of the rear left wheel as shown in the formula The target brake fluid pressure calculation process is terminated after setting the target brake fluid pressure Ps _RR to ½ of the rear wheel master cylinder pressure Pmr considering the front-rear distribution calculated from the master cylinder pressure Pm, and the predetermined main program is executed. Return.
Ps _FL = Ps _FR = Pmf / 2 (7)
Ps _RL = Ps _RR = Pmr / 2 (8)

On the other hand, when the determination result in step S31 is F _out = 1, the process proceeds to step S33, where it is determined whether or not the absolute value of the target yaw moment Ms is greater than or equal to a preset value Ms1. When Ms | <Ms1, the routine proceeds to step S34, where the target braking hydraulic pressure differences ΔPs _F and ΔPs _R are calculated based on the following equations (9) and (10), and only the difference between the braking forces of the rear left and right wheels is calculated. Then, the process proceeds to step S36 to be described later.
ΔPs _F = 0 (9)
ΔPs _R = K _br · Ms / T (10)

Here, T is the same tread for the front and rear wheels. _Kbr is a conversion coefficient for converting braking force into braking fluid pressure, and is determined by brake specifications.
On the other hand, when the determination result in step S33 is | Ms | ≧ Ms1, the process proceeds to step S35, and target brake hydraulic pressure differences ΔPs _F and ΔPs _R are calculated based on the following equations (11) and (12). Then, after setting so as to generate a difference in the braking force of each wheel, the process proceeds to step S36 described later.
ΔPs _F = K _bf · Ms / | Ms | · (| Ms | −Ms1) / T (11)
ΔPs _R = K _br · Ms / | Ms | · Ms1 / T (12)
Here, K _bf is a conversion coefficient for converting braking force into braking hydraulic pressure, and is determined by brake specifications. In this case, it is also possible to set ΔPs _F = K _bf · Ms / T by controlling only with the front wheels.

In step S36, it is determined whether or not the deceleration control operation flag Fgs is set to “1” meaning deceleration control operation. When Fgs = 1, the process proceeds to step S37 and is calculated in step S14. The target deceleration amount Ag is calculated based on the following equation (13) using the parameter Xa, and the process proceeds to step S39.
Ag = −Kv × (| Xs | − | X _L | −Xa) (13)
Here, Kv is a proportionality constant determined from vehicle specifications.
When the determination result of step S36 is Fgs = 0, the process proceeds to step S38, the target deceleration amount Ag is set to 0 (zero) based on the following equation (14), and then the process proceeds to step S39. .
Ag = 0 ……… (14)

In step S39, for the purpose of decelerating the host vehicle, the target braking hydraulic pressure Pg for generating braking force on both the left and right wheels is calculated based on the following equation (15), and then the process proceeds to step S40.
Pg = Kg × Ag (15)
Here, Kg is a proportionality constant determined from vehicle specifications. The target braking hydraulic pressure Pg as the traveling state deceleration amount calculated based on the traveling state of the host vehicle in this way is the minimum necessary for suppressing the occupant's uncomfortable feeling caused by the yaw moment applied to the vehicle during the departure avoidance control. This is the deceleration amount.

In step S40, it is determined whether or not the master cylinder hydraulic pressure Pm as the vehicle deceleration amount corresponding to the braking operation amount by the driver's braking operation is equal to or higher than the target braking hydraulic pressure Pg calculated in step S39. When ≧ Pg, the routine proceeds to step S41, where the departure direction of the host vehicle is determined, and when it deviates to the right, the target braking fluid pressure Ps _j of each wheel is calculated based on the following equation (16). If it is calculated and deviates to the left, the target braking fluid pressure calculation process is terminated after calculating the target braking fluid pressure Ps _j of each wheel based on the following equation (17), and a predetermined main program Return to.

Ps _FL = ΔPs _F / 2 + Pmf / 2
Ps _FR = −ΔPs _F / 2 + Pmf / 2
Ps _RL = ΔPs _R / 2 + Pmr / 2
Ps _RR = −ΔPs _R / 2 + Pmr / 2 (16)
Ps _FL = −ΔPs _F / 2 + Pmf / 2
Ps _FR = ΔPs _F / 2 + Pmf / 2
Ps _RL = −ΔPs _R / 2 + Pmr / 2
Ps _RR = ΔPs _R / 2 + Pmr / 2 (17)

Since the relationship between the driver's operation amount (stroke amount) Ls and the braking fluid pressure Pm corresponds to the broken line A in FIG. 7, in this case, for the final deceleration excluding the braking fluid pressure for generating the yaw moment. The braking hydraulic pressure is as shown by a solid line B in FIG.
When the determination result of step S40 is Pm <Pg, the process proceeds to step S42 to determine the departure direction of the host vehicle, and when deviating to the right, The target braking fluid pressure Ps _j of the wheel is calculated, and when deviating leftward, the target braking fluid pressure is calculated after calculating the target braking fluid pressure Ps _j of each wheel based on the following equation (19). The process is terminated and the process returns to a predetermined main program.

Ps _FL = ΔPs _F / 2 + Pgf / 2
Ps _FR = −ΔPs _F / 2 + Pgf / 2
Ps _RL = ΔPs _R / 2 + Pgr / 2,
Ps _RR = −ΔPs _R / 2 + Pgr / 2 (18)
Ps _FL = −ΔPs _F / 2 + Pgf / 2
Ps _FR = ΔPs _F / 2 + Pgf / 2
Ps _RL = −ΔPs _R / 2 + Pgr / 2
Ps _RR = ΔPs _R / 2 + Pgr / 2 (19)

Here, Pgf and Pgr are hydraulic pressures generated on the front and rear wheels in consideration of the front-rear distribution calculated from the target braking hydraulic pressure Pg.
Since the target brake fluid pressure Pg corresponds to the two-dot chain line C in FIG. 7, in this case, the brake fluid pressure for final deceleration excluding the brake fluid pressure for generating the yaw moment is the solid line D in FIG. As shown.
In the lane departure prevention control processing of FIGS. 2 and 6, the processing of steps S3 to S7 corresponds to the processing performed by the departure determination means, and the processing of steps S33 to S35 corresponds to the processing performed by the yaw control amount calculation means. The processing of S36 to S39 corresponds to the processing performed by the traveling state deceleration amount calculation means, and the processing of steps S32, S41 and S42 corresponds to the processing performed by the braking force control means.

Therefore, it is assumed that the host vehicle is traveling straight along the travel lane in a state where the driver does not perform a brake operation. In this case, in the departure prevention control process of FIG. 2, the departure estimated value Xs satisfying | Xs | <| X _L | is calculated in step S3. Therefore, the process proceeds from step S5 to step S6, and the departure determination flag F _out = 0, indicating that there is no tendency to deviate, and the determination in step S19 proceeds to step S22 to stop the alarm. In step S23, the target yaw moment Ms is set to “0”. Thus, the target braking pressure Ps _FL ~Ps _RR of each wheel 5FL~5RR in step S32 in FIG. 6, the master cylinder pressures Pmf and Pmr according to the brake operation of the driver are respectively set, the driver's steering operation The running state corresponding to is continued.

From this state, it is assumed that the vehicle gradually begins to deviate leftward from the center position of the travel lane due to the driver's sideways look. In this case, since the deviation estimate Xs is a departure boundary line X _L or more, the process proceeds from step S5 to step S7, a state indicating the deviation tendency becomes departure determination flag F _out = 1 . Then, the process proceeds to step S20 according to the determination in step S19, and an alarm is activated. In step S21, the target yaw moment Ms is calculated based on the equation (5). In step S39 in FIG. Although the brake fluid pressure Pg is calculated, the driver does not perform the brake operation. Therefore, the process proceeds to step S42 based on the determination in step S40, and the target brake pressure of each of the wheels 5FL to 5RR is calculated based on the equation (19). Ps _{FL to} Ps _RR are set. As a result, the course is corrected in the right direction, which is the departure avoidance direction, by the deceleration control that generates a braking force corresponding to the target braking hydraulic pressure Pg calculated according to the traveling state and the yaw control that gives the vehicle a yaw moment. Do exactly.

  Thus, when the host vehicle tends to deviate from the driving lane, the deviating prevention control is performed by combining the yaw control and the deceleration control. Therefore, a difference in braking force is applied to each wheel so that the yaw moment is given to the vehicle by the yaw control. This makes it possible to accurately correct the course in the departure avoidance direction, and to generate a braking force according to the traveling state of the host vehicle by the deceleration control, so that the occupant's A sense of incongruity can be reduced.

The driver performs a braking operation with the host vehicle deviating leftward from the center position of the traveling lane, and the master cylinder pressure Pm corresponding to the braking operation of the driver is calculated according to the traveling state. It is assumed that the target braking hydraulic pressure Pg is greater than or equal to. In this case, the process proceeds to step S41 it is determined in step S40 in FIG. 6, target brake pressures Ps _FL ~Ps _RR of each wheel 5FL~5RR on the basis of the equation (17) is set. As a result, a decelerating control that generates a braking force corresponding to the braking hydraulic pressure Pm detected according to the driver's braking operation and a yaw control that applies a yaw moment to the vehicle in the right direction that is the departure avoidance direction. Correct the course.

  As described above, when the host vehicle tends to depart from the driving lane, departure prevention control is performed by combining yaw control and deceleration control, and the amount of braking operation by the driver's brake operation is taken into account in the deceleration amount of deceleration control. By decelerating the vehicle, the amount of uncomfortable feeling to the driver can be reduced to the minimum necessary to reduce the uncomfortable feeling of the occupant due to the yaw moment applied to the vehicle. Durability can be improved.

  Further, when braking control (yaw control and deceleration control) for preventing lane departure is performed, the vehicle state deceleration calculated by the vehicle deceleration amount corresponding to the braking operation amount by the driver's brake operation and the traveling state of the host vehicle is used. Compared with the amount, the larger deceleration amount is used to perform the deceleration control, so even when the driver's braking operation is insufficient when the host vehicle tends to deviate, This can be compensated, and the uncomfortable feeling to the driver can be reduced.

  Furthermore, an obstacle is detected in front of the host vehicle, and the driver strongly brakes.The amount of deceleration caused by this braking operation is less than the minimum amount of deceleration necessary to suppress the passenger's discomfort due to the yaw moment applied to the vehicle. In the case of a large value, priority is given to the amount of deceleration by the driver's brake operation, so it is possible to avoid lane departure more safely without hindering the driver's danger avoidance operation.

Next, a second embodiment of the present invention will be described.
In the second embodiment, in the first embodiment described above, the amount of deceleration finally given to the host vehicle is shifted from the amount of deceleration caused by the driver's brake operation to the amount of deceleration calculated based on the running state. In this case, deceleration control is performed by setting so as to change smoothly.
As shown in FIG. 8, the target braking hydraulic pressure calculation process in the lane departure prevention control process executed by the control unit 8 is deleted from the processes in steps S40 to S42 in FIG. 6 in the first embodiment described above, and step S39. Step S51 for calculating the final deceleration amount ΔG to be given to the host vehicle is added after step S51, and step S52 for calculating the target braking pressures Ps _{FL to} Ps _RR of the wheels 5FL to 5RR is added after step S51. Except for, the same processing as the processing of FIG. 6 described above is executed, and the corresponding parts to FIG.

In step S51, a deceleration amount ΔG that is finally given to decelerate the host vehicle is calculated. FIG. 9 is a diagram showing the relationship between the stroke amount Ls and the deceleration amount ΔG. As shown in FIG. 9, in the relationship between the stroke amount and the braking fluid pressure shown in FIG. 7, the arc portion is provided so that the target braking fluid pressure Pg and the braking fluid pressure Pm by the driver operation intersect smoothly. This arc has a radius Rg, a center position (L ₀ , P ₀ ), and is in contact with the straight line P = Pg and the straight line P = Km · Ls.

Here, the straight line P = Km · Ls is a straight line showing the relationship between the driver's operation amount (stroke amount) and the brake fluid pressure, and Km is a constant.
Further, the radius Rg is calculated based on the target brake hydraulic pressure Pg with reference to the radius calculation map shown in FIG. This radius calculation map is set so that the radius Rg is calculated to increase as the target brake hydraulic pressure Pg increases. Therefore, a smoothly changing region (b in FIG. 9) between the deceleration amount due to the driver's braking operation and the deceleration amount calculated based on the traveling state is widened.

Accordingly, in FIG. 9, the braking fluid pressure ΔG in the range a is calculated based on the following equation (20), the braking fluid pressure ΔG in the range b is calculated based on the following equation (21), and the braking fluid pressure ΔG in the range c is calculated. The hydraulic pressure ΔG is calculated based on the following equation (22).
ΔG = Pg (20)
ΔG = P ₀ − {Rg ² − (Ls−L ₀ ) ² } ^1/2 (21)
ΔG = Km × Ls (22)
By calculating the braking fluid pressure ΔG in this way, the deceleration amount changes smoothly when the target braking fluid pressure Pg is shifted to the braking fluid pressure Pm by the driver's braking operation. Discomfort caused by the fact that the deceleration amount is not reflected until it exceeds the target deceleration amount, that is, when the driver's brake operation amount increases, the deceleration amount suddenly increases from the time when the deceleration amount by the driver operation exceeds the target deceleration amount The uncomfortable feeling by things can be suppressed.

Next, in step S52, the departure direction of the host vehicle is determined. If the vehicle deviates to the right, the target braking hydraulic pressure Ps _j for each wheel is calculated based on the following equation (23), and leftward If the vehicle deviates, the target braking fluid pressure Ps _j of each wheel is calculated based on the following equation (24), and then the target braking fluid pressure calculation process is terminated, and the program returns to a predetermined main program.
Ps _FL = ΔPs _F / 2 + ΔGf / 2
Ps _FR = −ΔPs _F / 2 + ΔGf / 2
Ps _RL = ΔPs _R / 2 + ΔGr / 2
Ps _RR = −ΔPs _R / 2 + ΔGr / 2 (23)
Ps _FL = −ΔPs _F / 2 + ΔGf / 2
Ps _FR = ΔPs _F / 2 + ΔGf / 2
Ps _RL = −ΔPs _R / 2 + ΔGr / 2
Ps _RR = ΔPs _R / 2 + ΔGr / 2 (24)
Here, ΔGf and ΔGr are hydraulic pressures generated at the front and rear wheels in consideration of the front-rear distribution calculated from the braking hydraulic pressure ΔG.

Accordingly, the vehicle tends to deviate from the traveling lane to the left while the driver is performing a braking operation at a master cylinder pressure Pm that is approximately the same as the target braking hydraulic pressure Pg calculated according to the traveling state. It shall be. In this case, in the target brake fluid pressure calculation process of FIG. 8, the brake fluid pressure ΔG is calculated based on the equation (21) in step S51, and each step based on the equation (24) in step S52. Target braking pressures Ps _{FL to} Ps _RR for the wheels 5FL to 5RR are set. Thus, in the departure avoidance direction, the deceleration control that generates a braking force corresponding to the deceleration amount larger than the target braking hydraulic pressure Pg calculated based on the traveling state of the host vehicle and the yaw control that gives the vehicle a yaw moment. Correct the course in the right direction.

  As described above, when braking control (yaw control and deceleration control) for preventing lane departure is performed, the deceleration amount finally given to the vehicle travels from the vehicle deceleration amount corresponding to the braking operation amount by the driver's brake operation. When shifting to the running state deceleration amount calculated based on the state, it is calculated so as to change smoothly, so even if the braking fluid pressure by the driver operation is below the target braking fluid pressure, the target braking When a braking force corresponding to a value greater than the hydraulic pressure is generated in the host vehicle, the driver can experience the driver's own braking operation, and departure avoidance control without a sense of incongruity can be performed.

Further, in the deceleration control, the amount of deceleration given to the vehicle is changed smoothly, so that when the braking fluid pressure by the driver operation exceeds the target braking fluid pressure, the amount of deceleration given to the vehicle is prevented from increasing suddenly, A sense of incongruity for the driver can be suppressed.
Furthermore, the larger the target braking hydraulic pressure calculated based on the running state, the more smoothly the region that changes, so the driver's braking operation is reliably reflected, and the deceleration amount suddenly increases from a certain stroke amount. A sense of incongruity can be reduced. In other words, when the target braking fluid pressure is high, the amount of stroke increases if the braking force is generated to exceed that fluid pressure, so that the deceleration amount suddenly increases from a certain amount of stroke, giving the driver a sense of incongruity. However, this uncomfortable feeling can be reduced by increasing the deceleration hydraulic pressure in accordance with the stroke amount.

In each of the above embodiments, the case where the driver performs warning notification when the driver does not change lanes and is in a tendency to depart from the lane has been described, but the present invention is not limited to this. There may be a difference between the timing to perform and the timing to perform braking control (yaw control and deceleration control). Since G is applied to the driver by using the braking control, the braking control itself can have a warning effect.
In each of the above embodiments, the case where the present invention is applied to a rear wheel drive vehicle has been described. However, the present invention can also be applied to a front wheel drive vehicle. In this case, in step S2, among the wheel speeds Vw _FL ~Vw _RR, left and right wheel speeds Vw _RL after a non-driven wheels, may be calculated vehicle speed V of the host vehicle from an average value of Vw _RR.

It is a schematic structure figure showing an embodiment of the present invention. It is a flowchart which shows the lane departure prevention control process performed with the control unit 8 of FIG. 1 in embodiment of this invention. It is a figure explaining a deviation estimated value. It is a parameter calculation map. It is a gain calculation map. 3 is a flowchart showing a target braking fluid pressure calculation process in the lane departure prevention control process of FIG. 2. It is a figure explaining the relationship between the stroke amount and braking fluid pressure in 1st Embodiment. It is a flowchart which shows the target brake hydraulic pressure calculation process in 2nd Embodiment. It is a figure explaining the relationship between the stroke amount and braking fluid pressure in 2nd Embodiment. It is a radius calculation map.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control circuit 8 Control unit 9 Engine 13 CCD camera 14 Camera controller 16 Master cylinder pressure sensor 20 Steering angle sensor 21FL to 21RR Wheel speed sensor 22 Direction indication switch 23 Stroke sensor 24 Alarm device

Claims (3)

In a lane departure prevention apparatus for controlling the host vehicle so as to avoid a departure from the traveling lane of the host vehicle,
Traveling state detecting means for estimating and detecting a deviation estimated value which is a lateral displacement in the traveling lane after a predetermined time of the host vehicle;
Braking operation amount detection means for detecting a braking operation amount by the driver's braking operation;
Deviation judging means for judging that the host vehicle is in a tendency to deviate from the traveling lane based on the deviation estimated value detected by the traveling state detecting means;
When the departure determination means determines that the host vehicle tends to depart from the traveling lane, the departure from the traveling lane of the own vehicle is avoided based on the estimated departure value detected by the traveling state detection means. A yaw control amount calculation means for calculating a first braking force control amount of each wheel so that a larger yaw moment is generated in the direction as the deviation estimation value is larger ;
When the estimated deviation value detected by the traveling condition detection means is greater than or equal to a predetermined value, a traveling condition deceleration amount calculating means that calculates a traveling condition deceleration amount that is a deceleration amount according to the estimated deviation value. And comparing the calculated traveling state deceleration amount and the vehicle deceleration amount corresponding to the braking operation amount detected by the braking operation amount detection means, the braking force corresponding to the larger deceleration amount is applied to the host vehicle. Braking control amount calculating means for calculating a second braking force control amount for each wheel to generate ,
A lane departure prevention apparatus comprising braking force control means for controlling the braking force of each wheel in accordance with the first and second braking force control amounts calculated by the yaw control amount calculating means and the braking control amount calculating means. . The braking control amount calculation means compares the traveling state deceleration amount calculated by the traveling state deceleration amount calculation means with the vehicle deceleration amount corresponding to the braking operation amount detected by the braking operation amount detection means, and is large. The braking force generated in the host vehicle changes smoothly when the deceleration amount of the vehicle shifts from the traveling state deceleration amount to the vehicle deceleration amount corresponding to the braking operation amount and vice versa. The lane departure prevention apparatus according to claim 1 , wherein the second braking force control amount of each wheel is calculated as described above. 3. The lane departure prevention device according to claim 2 , wherein the braking control amount calculating unit widens the smoothly changing region as the traveling state deceleration amount calculated by the traveling state deceleration amount calculating unit increases. .

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