JP3826758B2 - Lane departure prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
Conventionally, as such a lane departure prevention device, for example, there is one described in JP-A-11-96497. This lane departure prevention device determines that the host vehicle is likely to deviate from the traveling lane, and controls the steering so that the driver can easily overcome the lateral deviation of the traveling position of the host vehicle with respect to the reference position of the traveling lane. Lane departure is prevented by outputting torque by a steering actuator.
[0003]
[Problems to be solved by the invention]
By the way, since the conventional lane departure prevention device requires a steering actuator, the braking force or driving force of each wheel is controlled using, for example, an anti-skid control device or a driving force control device. It is conceivable to control the traveling direction or traveling position of the host vehicle by generating a moment.
[0004]
When the lane departure prevention device for controlling the braking / driving force of each wheel is configured in this way, the vehicle feels as if the host vehicle is being pushed back into the lane during the braking / driving force control. It is possible to inform the occupant that there is a tendency to depart, and experiments have shown that this is particularly effective when the caution of the occupant is reduced.
However, in such a lane departure prevention device, when large pitching occurs during braking / driving force control, it becomes difficult to give the occupant the feeling that the vehicle is being pushed back into the lane. There was a point.
[0005]
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the prior art, and suppresses pitching during braking / driving force control and feels that the host vehicle is pushed back into the lane. It is an object of the present invention to provide a travel lane departure prevention device that can provide a passenger with a lane.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problem, a lane departure prevention apparatus according to a first aspect of the present invention provides: Self Vehicle tends to deviate from driving lane Whether or not Deviation Judgment Means and The Vehicle tends to deviate from driving lane Judgment Is Then Yaw moment is generated in a direction that avoids deviation from the driving lane of the vehicle To each Braking / driving force control amount calculating means for calculating the braking / driving force control amount of the wheel; That Braking / driving force control means for controlling the braking / driving force of each wheel according to the braking / driving force control amount. When the braking / driving force control amount calculation means can calculate a plurality of braking / driving force control amounts that generate the yaw moment, the braking / driving force control amount calculation unit can calculate the plurality of braking / driving force control amounts as the braking / driving force control amount of each wheel. Calculate the braking / driving force control amount so that the difference in braking / driving force between the front and rear wheels is small. It is characterized by that.
[0007]
According to a second aspect of the present invention, in the lane departure prevention apparatus according to the first aspect of the present invention, the braking / driving force control means can individually control at least the braking forces of the left and right wheels.
The invention according to claim 3 is the lane departure prevention apparatus according to claim 2, wherein the braking / driving force control amount calculating means is When a plurality of braking / driving force control amounts for generating the yaw moment can be calculated, the braking / driving force control amounts for the respective wheels can be calculated as the braking / driving force control amounts for the wheels. , Self A braking force is generated on the front wheels on the side opposite to the direction of departure from the vehicle lane, and the braking force is applied to the rear left and right wheels of the host vehicle. But Occurrence You Like System A driving force control amount is calculated.
[0008]
Further, the invention according to claim 4 is the invention according to claim 1. From One of 3 1 item In the lane departure prevention apparatus which is the invention described in Predetermined Wheel But Slip state Whether or not The Judgment Slip state Judgment And the braking / driving force control amount calculating means includes the slip state. Judgment By means When it is determined that the predetermined wheel is in a slip state, when a plurality of braking / driving force control amounts for generating the yaw moment can be calculated, the plurality of braking / driving force control amounts for each wheel can be calculated. The braking / driving control amount of the predetermined wheel is small among the various braking / driving force control amounts. The braking / driving force control amount is calculated.
[0009]
In the invention according to claim 5, the braking / driving force control amount calculating means includes the braking / driving force control amount calculating means, If it is determined by the slip state determination means that the predetermined wheel is in a slip state, a plurality of braking / driving force control amounts for generating the yaw moment can be calculated. Of the plurality of computable braking / driving force control amounts, , The predetermined Limit the braking / driving force control amount of wheels Shi The above Predetermined Add the above limit to the braking / driving force control amount of the wheel symmetrical to the vehicle longitudinal direction. When the determined braking / driving force control amount is calculated, and the slip state determining means determines that the predetermined wheel is not in the slip state, a plurality of braking / driving force control amounts that generate the yaw moment can be calculated. As the braking / driving force control amount of each wheel, among the plurality of braking / driving force control amounts that can be calculated , The braking / driving force control amount is calculated so that the braking force is generated only on the front and rear wheels on the opposite side to the direction of departure from the traveling lane of the host vehicle. It is characterized by that.
[0010]
On the other hand, in order to solve the above-mentioned problem, a lane departure prevention device according to claim 6 is an invention. The Vehicle tends to deviate from driving lane Whether or not Deviation Judgment Means and The Vehicle tends to deviate from driving lane Judgment Is When A braking / driving force control amount calculating means for calculating a braking / driving force control amount of each wheel so that a yaw moment is generated in a direction avoiding a deviation from the traveling lane of the host vehicle; That The braking / driving force control means for controlling the braking / driving force of each wheel according to the braking / driving force control amount, and the braking / driving force control amount calculating means Left and right wheels Braking / driving force control amount If the difference is greater than the predetermined value Suspension device damping force The bigger And a damping force control means.
[0011]
Further, the invention according to claim 7 is the invention according to claim 1. From One of 6 1 item In the lane departure prevention apparatus according to the invention described in claim 2, the departure Judgment When the lateral displacement relative to the travel lane of the host vehicle in the future estimated from the travel state of the host vehicle detected by the travel state detection unit is equal to or greater than a predetermined lateral displacement limit value, the vehicle is moved from the travel lane. It is characterized by detecting the tendency to deviate.
[0012]
Further, the invention according to claim 8 is the invention according to claim 1. From One of 7 1 item In the lane departure prevention apparatus according to the present invention, the braking / driving force control amount calculating means includes The The difference between the lateral displacement and the lateral displacement limit value for the driving lane of the vehicle in the future estimated from the traveling state of the vehicle The bigger the is Calculate the target yaw moment So The braking / driving force control amount of each wheel is calculated based on the target yaw moment.
[0013]
【The invention's effect】
Therefore, in the lane departure prevention device which is the invention according to claim 1, , Example For example , Even if the yaw moment generated by the braking / driving force control is large and the difference in the braking / driving force control amount between the left and right wheels becomes large, the pitching during braking / driving force control is suppressed and the vehicle is pushed back into the lane Such a feeling can be given to the occupant, and the occupant can be informed that the host vehicle tends to depart from the lane.
[0014]
In the lane departure prevention apparatus according to the invention according to claim 2, ,left By controlling the braking force of the right wheel individually and matching the yaw moment generated in the vehicle with the target yaw moment in the lane departure avoidance direction, it is possible to avoid departure from the driving lane. Since it does not affect the driver, the driver does not feel uncomfortable.
[0015]
Moreover, in the lane departure prevention apparatus which is the invention according to claim 3, ,rear The braking force generated by each of the wheels is small, and the slip amount of the rear wheel is small, so that it is possible to prevent the control ability from being lowered due to the slip.
[0016]
Furthermore, in the lane departure prevention apparatus which is the invention according to claim 4, , Example For example , Slip state The braking / driving force control amount of the wheel in the vehicle is reduced, and the braking / driving force of the other wheels is increased to prevent the control ability from being reduced due to slipping. The driving force control amount can be made appropriate.
[0017]
In the lane departure prevention apparatus according to the invention according to claim 5, , System The yaw moment can be reliably generated by the driving force control, and the deterioration of the control ability due to the slip can be prevented.
[0018]
Furthermore, in the lane departure prevention apparatus which is the invention according to claim 6, , Example For example, even if the yaw moment generated by the braking / driving force control is large and the difference in the braking / driving force control amount between the left and right wheels is large, by increasing the damping force of the suspension device, Rolling does not occur, it is possible to give the occupant a feeling that the host vehicle is being pushed back into the lane, and it is possible to notify the occupant that the host vehicle tends to depart from the lane.
[0019]
Moreover, in the lane departure prevention apparatus which is the invention according to claim 7, The The lateral position of the vehicle with respect to the traveling lane can be made appropriate.
In the lane departure prevention apparatus according to the invention according to claim 8, , Example For example , The larger the difference between the lateral displacement and the lateral displacement limit value, the larger the target yaw moment, and the departure from the traveling lane can be surely avoided.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of a lane departure prevention apparatus of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of a vehicle illustrating an example of a lane departure prevention apparatus according to the present embodiment. 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 of the left and right wheels independently of the front and rear wheels.
[0021]
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 depends on the amount of depression of the brake pedal 1 by the driver. The brake fluid pressure control circuit 7 is interposed between the master cylinder 3 and the wheel cylinders 6FL to 6RR. In the braking fluid pressure control circuit 7, the braking fluid pressures of the wheel cylinders 6FL to 6RR can be individually controlled.
[0022]
The brake fluid pressure control circuit 7 uses a brake fluid pressure control circuit used for, for example, anti-skid control and traction control. In this embodiment, the brake fluid pressures of the wheel cylinders 6FL to 6RR are 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 braking / driving force control unit 8 described later.
[0023]
In addition, the vehicle controls the driving torque to the rear wheels 5RL and 5RR, which are driving wheels, by controlling the operating state of the engine 9, the selected transmission ratio of the automatic transmission 10, and the throttle opening of the throttle valve 11. A drive torque control unit 12 is provided. The operating state control of the engine 9 can be controlled, for example, by controlling the fuel injection amount and the ignition timing, and can also be controlled by controlling the throttle opening at the same time. The drive torque control unit 12 can independently control the drive torque of the rear wheels 5RL and 5RR that are drive wheels. However, the drive torque command value from the braking / driving force control unit 8 described above can be controlled. When input, the drive wheel torque is controlled with reference to the drive torque command value.
[0024]
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, for example, a lane marker such as a white line from a captured image captured in front of the host vehicle captured by the CCD camera 13 to detect a travel lane, and the yaw angle φ of the host vehicle with respect to the travel lane, the center of the travel lane The lateral displacement X from the vehicle, the curvature β of the traveling lane, the traveling lane width L, and the like can be calculated.
[0025]
Further, the vehicle includes an acceleration sensor 15 that detects longitudinal acceleration Xg and lateral acceleration Yg generated in the host vehicle, a yaw rate sensor 16 that detects yaw rate φ ′ generated in the host vehicle, an output pressure of the master cylinder 3, so-called A master cylinder pressure sensor 17 that detects the master cylinder pressure Pm, an accelerator pedal depression amount, that is, an accelerator opening sensor 18 that detects the accelerator opening Acc, a steering angle sensor 19 that detects the steering angle δ of the steering wheel 21, and each wheel There are provided wheel speed sensors 22FL to 22RR for detecting a rotational speed of 5FL to 5RR, so-called wheel speed Vwi (i = FL to RR), and a direction indicating switch 20 for detecting a direction indicating operation by a direction indicator, and detection signals thereof. Is output to the braking / driving force control unit 8. Further, the yaw angle φ of the host vehicle with respect to the travel lane detected by the camera controller 14, the lateral displacement X from the center of the travel lane, the curvature β of the travel lane, the travel lane width L, and the like are controlled by the drive torque control unit 12. The driving torque Tw is also output to the braking / driving force control unit 8 together. If the detected vehicle traveling state data has left and right directions, the left direction is the positive direction. That is, the yaw rate φ ′, the lateral acceleration Yg, the steering angle δ, and the yaw angle φ are positive values when turning left, and the lateral displacement X is a positive value when deviating from the center of the traveling lane to the left.
[0026]
Further, this vehicle is provided with an in-vehicle information presentation device 23 having a display and a speaker, and presents a stop of the lane departure prevention control or the like to the occupant in response to a command from the braking / driving force control unit 8.
Next, the logic of the arithmetic processing performed in the braking / driving force control unit 8 will be described with reference to the flowchart of FIG. This calculation process is executed by a timer interruption every predetermined sampling time ΔT every 10 msec., For example. In this flowchart, no communication step is provided, but information obtained by the arithmetic processing is updated and stored in the storage device as needed, and necessary information is read out from the storage device as needed.
[0027]
In this calculation process, first, in step S1, various data from the sensors, the controller, and the control unit are read. Specifically, the longitudinal acceleration Xg, lateral acceleration Yg, yaw rate φ ′ detected by each sensor, each wheel speed Vwi, accelerator opening Acc, master cylinder pressure Pm, steering angle δ, direction indicating switch signal, and driving The driving torque Tw from the torque control unit 12, the yaw angle φ of the host vehicle with respect to the travel lane, 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.
[0028]
Next, the process proceeds to step S2, and the traveling speed V of the host vehicle is calculated from the average value of the front left and right wheel speeds VwFL and VwFR which are non-driven wheels among the wheel speeds Vwi read in step S1.
Next, the process proceeds to step S3, where a future estimated lateral displacement XS is calculated as an estimated deviation value. Specifically, the yaw angle φ with respect to the traveling lane of the host vehicle, the lateral displacement X from the center of the traveling lane, the curvature β of the traveling lane, and the traveling speed V of the own vehicle calculated in step S2 are used. The future estimated lateral displacement XS is calculated according to the following equation (1).
[0029]
XS = Tt × V × (φ + Tt × V × β) + X (1)
Here, Tt is the vehicle head time for calculating the forward gaze distance. When the vehicle head time Tt is multiplied by the traveling speed V of the host vehicle, the front gaze distance is obtained. 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, in the present embodiment, when the estimated lateral displacement XS in the future is equal to or greater than a predetermined lateral displacement limit value, it is determined that the host vehicle may deviate from the driving lane or tend to deviate. It is.
[0030]
Next, the process proceeds to step S4, and the turning state is determined. Specifically, when the absolute value of the lateral acceleration Yg read in step S1 is equal to or greater than a predetermined positive value Yg0, it is determined that the vehicle is turning suddenly, and the vehicle instability flag FCS is set. Further, the vehicle instability flag FCS is reset when the vehicle is not turning suddenly. In addition to this, the yaw rate φ ′ read in step S1 is compared with the target yaw rate obtained from the traveling speed V and the steering angle δ of the host vehicle as shown in FIG. The state, so-called oversteer or understeer, may be determined, and the vehicle instability flag FCS may be set in consideration of the determination results.
[0031]
Next, the process proceeds to step S5, where the driver's intention is determined. Specifically, the traveling direction (left / right direction) of the host vehicle determined from at least one of the steering angle δ and the direction indicating switch read in step S1, and the estimated lateral displacement XS calculated in step S3. When the traveling direction of the host vehicle determined from the sign (the left direction is positive) matches, it is determined that the lane change is intentional, and the lane change determination flag FLC is set. When the two do not match, the lane change determination flag FLC is reset.
[0032]
Next, the process proceeds to step S6, where it is determined whether or not to warn that the own vehicle is in a tendency to deviate from the traveling lane. Specifically, it is assumed that an alarm is issued when the absolute value | XS | of the estimated future lateral displacement as the deviation estimated value calculated in step S3 is equal to or greater than a predetermined lateral displacement limit value Xc (for example, 0.8 m). If not, no alarm will be given. A slight margin may be provided between the absolute value | XS | of the estimated lateral displacement and the lateral displacement limit value Xc. Further, a hysteresis may be provided in the threshold value in order to prevent alarm hunting. Further, the lateral displacement limit value Xc is the smaller of a value obtained by subtracting a half value of the vehicle width L0 of the host vehicle from a half value of the travel lane width L read in step S1 and a predetermined value (for example, 0.8 m). You may set to the value of.
[0033]
Next, the process proceeds to step S7, where it is determined whether or not the host vehicle tends to deviate from the traveling lane. Specifically, as in step S6, when the absolute value | XS | of the estimated future lateral displacement as the deviation estimated value calculated in step S3 is equal to or greater than the lateral displacement limit value Xc, The departure determination flag FLD is set because it is deviating from the traveling lane, and if not, the departure determination flag FLD is reset because the vehicle is not deviating from the traveling lane. However, when the vehicle instability flag FCS set in step S4 is in the set state, or when the lane change determination flag FLC set in step S5 is in the set state, the lane departure prevention control is not performed. In this case, the departure determination flag FLD is reset even if the absolute value | XS | of the estimated future lateral displacement is equal to or greater than the lateral displacement limit value Xc.
[0034]
Thus, in the present embodiment, when the estimated lateral displacement XS estimated from the traveling state of the host vehicle is equal to or greater than the predetermined lateral displacement limit value Xc, the host vehicle tends to deviate from the traveling lane. In order to detect, the lateral position with respect to the traveling lane of the own vehicle can be made appropriate.
Next, the process proceeds to step S8, where the target yaw moment is calculated and set. Here, the target yaw moment Ms is set only when the departure determination flag FLD is set. Therefore, when the departure determination flag FLD is set, the proportionality coefficient K1 determined from the vehicle specifications and FIG. The target yaw moment Ms is calculated according to the following two formulas using the proportional coefficient K2 set in accordance with the travel speed V shown, the estimated future lateral displacement XS calculated in step S3, and the lateral displacement limit value Xc. To do.
[0035]
Ms = −K1 × K2 × (XS−Xc) (2)
As described above, in the present embodiment, the target yaw moment Ms is calculated from the difference between the estimated lateral displacement XS and the lateral displacement limit value Xc estimated from the traveling state of the host vehicle. As the difference from the displacement limit value Xc increases, the target yaw moment increases, and deviation from the traveling lane can be reliably avoided.
[0036]
When the departure determination flag FLD is in the reset state, the target yaw moment Ms is set to “0”.
Next, the process proceeds to step S9 to calculate a target braking force BFi for each wheel. Specifically, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms1, a braking force equal to the front and rear wheels on the opposite side to the direction of departure from the traveling lane of the host vehicle is generated, and the target yaw moment When the absolute value | Ms | is equal to or greater than the predetermined value Ms1, a braking force is generated on the front wheel on the opposite side to the direction of departure from the traveling lane of the host vehicle, and the left and right rear left and right so that the difference in braking / driving force between the front and rear wheels becomes small Generate braking force on the wheels. Accordingly, the absolute value of the target yaw moment | Ms | is less than the predetermined value Ms1, and the target yaw moment Ms is a negative value, that is, the target braking force of the front and rear left wheels when the host vehicle is about to deviate in the left direction. BFfl and BFrl are “0”, and the target braking forces BFfr and BFrr of the front and rear right wheels are given by the following three equations. The target yaw moment Ms is a positive value, that is, the target braking forces BFfr and BFrr of the front and rear right wheels when the vehicle is about to deviate to the right are “0”, and the target braking forces BFfl and BFrl of the front and rear left wheels are Is given by the following four equations. Note that T in the formula indicates a tread (the same applies to the front and rear wheels).
[0037]
BFfr = BFrr = | Ms | / T (3)
BFfl = BFrl = | Ms | / T (4)
Accordingly, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms1, that is, when the braking / driving force difference between the left and right wheels of the host vehicle is small, the braking force distribution BFfl + BFfr: BFrl + BFrl of the front and rear wheels is 1: 1. The braking force difference between the front and rear wheels becomes “0”.
[0038]
Similarly, the target braking force of the front left wheel when the absolute value | Ms | of the target yaw moment is equal to or greater than the predetermined value Ms1 and the target yaw moment Ms is a negative value, that is, when the host vehicle is about to deviate in the left direction. BFfl is “0”, and the target braking forces BFfr, BFrl, and BFrr for the front right wheel and the rear left and right wheels are given by the following five equations. Also, the target yaw moment Ms is a positive value, that is, the target braking force BFfr of the front right wheel when the host vehicle is about to deviate in the right direction is “0”, and the target braking force BFfl of the front left wheel and the rear left and right wheels is , BFrl, BFrr are given by the following six equations.
[0039]
BFfr = | Ms | / T + 2 × (| Ms | −Ms1) / T
BFrl = (| Ms | -Ms1) / T
BFrr = Ms1 / T ……… (5)
BFfl = | Ms | / T + 2 × (| Ms | −Ms1) / T
BFrl = Ms1 / T
BFrr = (| Ms | −Ms1) / T (6)
Accordingly, when the absolute value | Ms | of the target yaw moment is equal to or greater than the predetermined value Ms1, that is, the braking / driving force difference between the left and right wheels of the host vehicle is large, the braking force distribution BFfl + BFfr: BFrl + BFrl of the front and rear wheels is (3 | Ms | −2Ms1). ): | Ms | is not necessarily 1: 1, but the braking force difference between the front and rear wheels is sufficiently small.
[0040]
As described above, in this embodiment, when the target yaw moment Ms is large and the braking force difference between the left and right wheels of the host vehicle is large, the braking force is applied to the front wheel on the opposite side to the direction of departure from the traveling lane of the host vehicle. In addition to generating a braking force on the rear left and right wheels of the host vehicle, the braking / driving force control amount of each wheel is calculated so that the braking / driving force difference between the front and rear wheels is reduced. The braking force to be applied is small and the slip amount of the rear wheel is small, so that the control ability can be prevented from being lowered due to the slip.
[0041]
Next, the process proceeds to step S10, and the target braking fluid pressure Psi for each wheel is calculated. When the master cylinder pressure Pm read in step S1 is set to PmR for the rear wheel master cylinder pressure based on the front / rear braking force distribution, and the departure determination flag FLD is in the reset state, the front left and right wheels 5FL, 5FR The target brake fluid pressures PSFL and PSFR to the wheel cylinders 6FL and 6FR are both master cylinder pressures Pm, and the target brake fluid pressures PSRL and PSRR to the wheel cylinders 6RL and 6RR of the rear left and right wheels 5RL and 5RR are both master cylinders for the rear wheels. The pressure becomes PmR.
[0042]
On the other hand, when the departure determination flag FLD is set, the target braking fluid pressure Psi to each of the wheel cylinders 6FL to 6RR has a value corresponding to the target braking force BFi of each wheel calculated in step S9. They are given by the following seven formulas that are added to the master cylinder pressures Pm and PmR, respectively. In the equation, Kbf and Kbr are conversion coefficients determined from brake specifications and wheel loads (in consideration of weighted movement).
[0043]
PSFL = Pm + Kbf × BFfl
PSFR = Pm + Kbf × BFfr
PSRL = PmR + Kbr × BFrl
PSRR = PmR + Kbr × BFrr (7)
Note that the method of calculating the target brake fluid pressure Psi is not limited to the method of adding the brake fluid pressure corresponding to the target brake force BFi of each wheel to the master cylinder pressures Pm and PmR of each wheel. The braking force difference may be set for the left and right wheels with the pressures Pm and PmR as median values. In the method of calculating the target braking fluid pressure Psi by setting the braking force difference, the wheel cylinders 6FL to 6RR when the target yaw moment Ms is a negative value, that is, when the host vehicle is about to deviate in the left direction. The target braking fluid pressure Psi is calculated by the following eight equations.
[0044]
PSFL = Pm- (BFfr-BFfl) / 2
PSFR = Pm + (BFfr-BFfl) / 2
PSRL = PmR- (BFrr-BFrl) / 2
PSRR = PmR + (BFrr-BFrl) / 2 (8)
However, when the half of the value obtained by subtracting the target braking force BFfl of the front left wheel from the target braking force BFfr of the front right wheel is equal to or higher than the master cylinder pressure Pm, the target braking fluid pressure PSFL of the front left wheel is set to “0”. The target braking fluid pressure PSFR for the right wheel is (BFfr−BFfl). Further, when the half value of the value obtained by subtracting the rear left wheel target braking force BFrl from the rear right wheel target braking force BFrr is equal to or higher than the master cylinder pressure Pm, the rear left wheel target braking fluid pressure PSFL is set to “0”. The target braking fluid pressure PSRR for the right wheel is set to (BFrr−BFrl).
[0045]
On the other hand, when the target yaw moment Ms is a positive value, that is, when the host vehicle is about to depart from the lane in the right direction, the target braking fluid pressure Psi to each of the wheel cylinders 6FL to 6RR is calculated by the following equation (9). The
PSFL = Pm + (BFfl-BFfr) / 2
PSFR = Pm- (BFfl-BFfr) / 2
PSRL = PmR + (BFrl−BFrr) / 2
PSRR = PmR- (BFrl-BFrr) / 2 (9)
However, when the half of the value obtained by subtracting the target braking force BFfr of the front right wheel from the target braking force BFfl of the front left wheel is equal to or higher than the master cylinder pressure Pm, the target braking fluid pressure PSFR of the front right wheel is set to “0”. The target braking fluid pressure PSFL of the front left wheel is set to (BFfl−BFfr). Further, when the half value of the value obtained by subtracting the rear right wheel target braking force BFrr from the rear left wheel target braking force BFrl is equal to or higher than the master cylinder pressure Pm, the rear right wheel target braking fluid pressure PSRR is set to “0”. A target braking fluid pressure PSFL of the rear left wheel is set to (BFrl−BFrr).
[0046]
Next, the process proceeds to step S11 to calculate the target driving force of the driving wheel. In the present embodiment, the departure determination flag FLD is set, and when the lane departure prevention control is performed, even if the accelerator operation is performed, the engine output is reduced so that acceleration cannot be performed. Accordingly, the target driving torque TrqDS when the departure determination flag FLD is set is a value corresponding to the sum of the target braking fluid pressure differences between the front and rear wheels, from the value corresponding to the accelerator opening Acc read in step S1. Reduced value. That is, the value according to the accelerator opening Acc is a driving torque for accelerating the host vehicle according to the accelerator opening Acc, and the value according to the sum of the target braking fluid pressure differences between the front and rear wheels is the target braking fluid. This is the braking torque generated by the sum of the pressure differences. Therefore, when the departure determination flag FLD is set and the lane departure prevention control is performed, the engine torque is reduced by the amount of braking torque generated by the sum of the target braking fluid pressure differences ΔPSF and ΔPSR. Note that the target drive torque TrqDS when the departure determination flag FLD is reset is only the drive torque for accelerating the host vehicle in accordance with the accelerator opening Acc.
[0047]
Next, the process proceeds to step S12, in which the target braking fluid pressure of each wheel calculated in step S10 is output to the braking fluid pressure control circuit 7, and the target driving of the driving wheel calculated in step S11 is performed. After the torque is output to the drive torque control unit 12, the program returns to the main program.
According to this calculation process, when the vehicle is not in a sudden turning state, is not intentionally changed by the driver, and the estimated lateral displacement XS is equal to or greater than the lateral displacement limit value Xc, the host vehicle The deviation determination flag FLD is set and the target yaw moment Ms is calculated based on the difference between the estimated lateral displacement XS and the lateral displacement limit value Xc, and the target yaw moment Ms is determined. As shown in FIG. 5a, the same braking force is generated on the front and rear wheels on the side opposite to the direction of departure from the traveling lane of the host vehicle so that the braking force of the front and rear wheels becomes equal. As a result, for example, when the steering input is small, a yaw moment that prevents the vehicle from departing from the lane is generated to prevent the vehicle from departing from the lane, and the traveling speed of the vehicle is reduced by the braking force. Therefore, it is possible to prevent lane departure. For example, even if the target yaw moment Ms is large and the difference in braking force between the left and right wheels is large, no large pitching occurs during braking / driving force control, and the host vehicle is pushed back into the lane. A feeling can be given to the occupant and the occupant can be informed that the host vehicle is in a lane departure tendency. Incidentally, FIG. 5c is an example in which braking force is generated only on the front wheel on the side opposite to the direction of departure from the traveling lane of the host vehicle, and large pitching occurs during braking / driving force control. It is impossible to give the occupant the feeling of being pushed back.
[0048]
In this embodiment, when the magnitude of the target yaw moment Ms becomes equal to or greater than the predetermined value Ms1, as shown in FIG. 5b, a braking force is generated on the front wheel on the side opposite to the direction of departure from the traveling lane of the host vehicle. At the same time, the braking force is generated on the rear left and right wheels so that the difference in braking / driving force between the front and rear wheels is reduced, so that the braking force generated by each of the rear wheels is reduced and the slip amount of the rear wheel is reduced. Thus, a decrease in control capability due to slip is suppressed and prevented.
[0049]
Next, a second embodiment of the lane departure prevention apparatus of the present invention will be described. In this embodiment, the arithmetic processing performed by the braking / driving force control unit 8 of the first embodiment is changed from that of FIG. 2 of the first embodiment to that of FIG.
The arithmetic processing in FIG. 6 includes many steps equivalent to the arithmetic processing in FIG. 2 of the first embodiment, and the same steps are denoted by the same reference numerals and detailed description thereof is omitted. In the calculation process of FIG. 6, step S13 is provided between steps S8 and S9 of the calculation process of FIG. 2, and step S9 is changed to step S9 ′.
[0050]
Among these, in step S13, a value obtained by subtracting the rear left wheel speed VwFL, which is the driving wheel, from the wheel speed Vwi read in step S1 from the traveling speed V of the host vehicle calculated in step S2 is a predetermined setting. It is determined whether or not the value is greater than or equal to the value Slmt. If the value is greater than or equal to the set value Slmt, it is determined that the rear left wheel is slipping, and the rear left wheel slip rise determination flag Fslp_rl is set. When the rear left wheel is not slipping, the rear left wheel slip rise determination flag Fslp_rl is reset.
[0051]
Similarly, it is determined whether the value obtained by subtracting the right wheel speed VwFR read in step S1 from the traveling speed V of the host vehicle calculated in step S2 is equal to or greater than a predetermined set value Slmt. When the value is greater than or equal to the value Slmt, it is determined that the rear right wheel is slipping, and the rear right wheel slip rise determination flag Fslp_rr is set. When the rear right wheel is not slipping, the rear right wheel slip rise determination flag Fslp_rr is reset.
[0052]
Next, the process proceeds to step S9 ′ to calculate a target braking force BFi for each wheel. Here, when the rear wheel slip increase determination flag Fslp_i is in the reset state, a braking force equal to the front and rear wheels on the opposite side to the direction of departure from the traveling lane of the host vehicle is generated, and the rear wheel slip increase determination flag Fslp_i is set. When the vehicle is in a state, braking force is generated on the front wheels on the side opposite to the direction of departure from the traveling lane of the host vehicle, and braking force is generated on the rear left and right wheels so that the braking force of the slipping wheels is reduced. Accordingly, the set state of the rear right wheel slip increase determination flag Fslp_rr and the rear left wheel slip increase determination flag Fslp_rl is the same, and the target yaw moment Ms is negative, that is, the host vehicle is about to deviate in the left direction. At this time, the target braking forces BFfl and BFrl of the front and rear left wheels are “0”, and the target braking forces BFrl and BFrr of the front and rear right wheels are given by the following equation (10). The target yaw moment Ms is a positive value, that is, the target braking forces BFfr and BFrr of the front and rear right wheels when the vehicle is about to deviate to the right are “0”, and the target braking forces BFfl and BFrl of the front and rear left wheels are Is given by the following equation (11). Note that T in the formula indicates a tread (the same applies to the front and rear wheels).
[0053]
BFfr = BFrr = | Ms | / T (10)
BFfl = BFrl = | Ms | / T (11)
Similarly, the rear right wheel slip increase determination flag Fslp_rr is in the set state, the rear left wheel slip increase determination flag Fslp_rl is in the reset state, and the target yaw moment Ms is a negative value, that is, the host vehicle lanes in the left direction. The target braking force BFfl of the front left wheel when deviating is “0”, and the target braking forces BFfr, BFrl, BFrr of the front right wheel and the rear left and right wheels are given by the following equation (12). Further, the rear right wheel slip rise determination flag Fslp_rr is in a reset state, the rear left wheel slip rise determination flag Fslp_rl is in a set state, and the target yaw moment Ms is a positive value, that is, the host vehicle deviates to the right. The target braking force BFfr of the front left wheel when trying to do so is “0”, and the target braking forces BFfl, BFrl, BFrr of the front left wheel and the rear left and right wheels are given by the following equation (13). In the equation, BFrr_on is the rear right wheel target braking force when the slip increase determination flag Fslp_rl changes from the reset state to the set state, and BFrl_on is when the slip increase determination flag Fslp_rl changes from the reset state to the set state. This is the target braking force for the rear left wheel.
[0054]
BFfr = 3x | Ms | / T-2xBFrr_on
BFrl = | Ms | / T-BFrr_on
BFrr = BFrr_on (12)
BFfl = 3x | Ms | / T-2xBFrl_on
BFrl = BFrl_on
BFrr = | Ms | / T-BFrl_on ………… (13)
According to this calculation process, as in the first embodiment, the vehicle is not in a sudden turning state, is not intentionally changed by the driver, and the estimated lateral displacement XS in the future is equal to or greater than the lateral displacement limit value Xc. At the time, it is determined that the host vehicle tends to deviate from the driving lane, and the departure determination flag FLD is set. Based on the difference between the estimated lateral displacement XS and the lateral displacement limit value Xc in the future, the target yaw moment Ms As shown in FIG. 7a, the front and rear wheels on the opposite side to the direction of departure from the traveling lane of the host vehicle are calculated so that the target yaw moment Ms is achieved and the braking forces of the front and rear wheels are equal. A braking force equal to is generated. As a result, for example, when the steering input is small, a yaw moment that prevents the lane departure is generated in the vehicle and the lane departure is prevented, and the traveling speed of the vehicle is reduced by the braking force. Can be prevented.
[0055]
Further, in this embodiment, when the difference between the traveling speed V of the host vehicle and the rear left wheel speed VwFL, or the difference between the traveling speed V of the host vehicle and the rear right wheel speed VwFR exceeds the set value Slmt, the rear wheel slips. As shown in FIG. 7b, the braking force of the slip-prone wheels is limited and the slip-prone wheels are symmetrical in the vehicle front-rear direction. Since the limit is added to the braking force of the wheel, the yaw moment is reliably generated by the braking / driving force control, and the control capability is prevented from being lowered due to the slip. In addition, in this embodiment, although the example which detects that a rear wheel has a slip tendency was shown, it is not limited to this, and it is detected that a front wheel has a slip tendency and has a slip tendency. You may make it restrict | limit the braking force of the front wheel from which this was detected.
[0056]
Next, a third embodiment of the lane departure prevention apparatus of the present invention will be described. The vehicle schematic configuration of this embodiment includes a suspension device having a shock absorber that can switch the magnitude of the damping force in five stages in addition to the one shown in FIG. 1 of the first embodiment. Other configurations are the same as those in FIG. 1 of the first embodiment.
[0057]
The flowchart of FIG. 8 shows the arithmetic processing performed by the braking / driving force control unit 8 of this embodiment. The arithmetic processing in FIG. 8 includes many steps equivalent to the arithmetic processing in FIG. 2 of the first embodiment, and the same steps are denoted by the same reference numerals and detailed description thereof is omitted. In the calculation process of FIG. 8, the step S9 of the calculation process of FIG. 2 is changed to step S9 ″, and the step S10 is changed to S10 ″.
[0058]
Among these, in step S9 ″, the target braking fluid pressure Psi for each wheel is calculated. The master cylinder pressure for rear wheels based on the front / rear braking force distribution is set to PmR with respect to the master cylinder pressure Pm read in step S1. When the departure determination flag FLD is in the reset state, the target brake fluid pressure PSFL and PSFR to the wheel cylinders 6FL and 6FR of the front left and right wheels 5FL and 5FR are both the master cylinder pressure Pm, and the rear left and right wheels 5RL and 5RR are The target brake fluid pressures PSRL and PSRR applied to the wheel cylinders 6RL and 6RR are both the rear wheel master cylinder pressure PmR.
[0059]
On the other hand, even when the departure determination flag FLD is set, the target to each of the wheel cylinders 6FL to 6RR when the target yaw moment Ms is a negative value, that is, when the own vehicle is about to leave the lane in the left direction. The braking fluid pressure Psi is given by the following equation (14).
PSFL = Pm
PSFR = Pm + ΔPsf
PSRL = PmR
PSRR ＝ PmR ……… (14)
However, front left and right wheel braking fluid differential pressure ΔPsf = 2 × Kbf × | Ms | / T
On the other hand, when the target yaw moment Ms is a positive value, that is, when the host vehicle is about to deviate in the right direction, the target braking fluid pressure Psi to the wheel cylinders 6FL to 6RR is given by the following equation (15). .
[0060]
PSFL = Pm + ΔPsf
PSFR = Pm
PSRL = PmR
PSRR ＝ PmR ……… (15)
In step S10 ″, the magnitude of the damping force of the shock absorber is set. Here, the magnitude of the damping force of the shock absorber is set only when the deviation determination flag FLD is set. When the determination flag FLD is set and the front left and right wheel braking fluid differential pressure ΔPsf is equal to or less than the predetermined value ΔPss, the damping force is set one step larger than the set value when the departure determination flag FLD is set. When the front left and right wheel braking fluid differential pressure ΔPsf is larger than the predetermined value ΔPss, the damping force is set two steps larger than the set value at the time when the departure determination flag FLD is set.
[0061]
According to this calculation process, as in the first embodiment, the vehicle is not in a sudden turning state, is not intentionally changed by the driver, and the estimated lateral displacement XS in the future is equal to or greater than the lateral displacement limit value Xc. At the time, it is determined that the host vehicle tends to deviate from the driving lane, and the departure determination flag FLD is set. Based on the difference between the estimated lateral displacement XS and the lateral displacement limit value Xc in the future, the target yaw moment Ms And a braking force is generated so that the target yaw moment Ms is achieved.
[0062]
Further, when the deviation determination flag FLD is set, the damping force of the shock absorber is set to be large according to the magnitude of the target yaw moment Ms, so that the target yaw moment Ms is set to be large and the braking / driving force of the left and right wheels is set. Even if the difference becomes large, large pitching or rolling does not occur during braking / driving force control, and it is possible to give the passenger a feeling that the vehicle is being pushed back into the lane. The occupant can be given a feeling that the vehicle is pushed back to the vehicle, and the occupant can be informed that the vehicle is in a lane departure tendency.
[0063]
In the above embodiment, each sensor and camera controller 14 of FIG. 1 and step S1 of the arithmetic processing of FIG. 2 constitute the running state detecting means of the present invention. Similarly, step S3 of the arithmetic processing of FIG. 2 constitutes a departure determination means, and steps S9, S10, S9 ′ and S9 ″ of the calculation processes of FIGS. 2, 6 and 8 constitute a braking / driving force control amount calculation means, and the braking fluid pressure control circuit 7 of FIG. The driving torque control unit 12 constitutes a braking / driving force control means, and step S13 of the arithmetic processing in FIG. 6 constitutes a slip state detecting means.
Moreover, the said embodiment shows an example of the lane departure prevention apparatus of this invention, and does not limit the structure of an apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a vehicle equipped with a lane departure prevention apparatus of the present invention.
FIG. 2 is a flowchart showing a first embodiment of information calculation processing executed in the braking / driving force control unit of FIG. 1;
FIG. 3 is a control map used for the arithmetic processing of FIG. 2;
4 is a control map used for the arithmetic processing of FIG.
FIG. 5 is an explanatory diagram of the operation of the arithmetic processing in FIG. 2;
6 is a flowchart showing a second embodiment of information calculation processing executed in the braking / driving force control unit of FIG. 1; FIG.
7 is an explanatory diagram of the operation of the arithmetic processing in FIG. 6;
FIG. 8 is a flowchart showing a third embodiment of information calculation processing executed in the braking / driving force control unit of FIG. 1;
[Explanation of symbols]
6FL-6RR is a wheel cylinder
7 is a brake fluid pressure control circuit
8 is a braking / driving force control unit
9 is the engine
12 is a drive torque control unit.
13 is a CCD camera
14 is a camera controller
15 is an acceleration sensor
16 is a yaw rate sensor
17 is a master cylinder pressure sensor
18 is an accelerator opening sensor.
19 is a steering angle sensor
20 is a direction indicator switch
22FL to 22RR are wheel speed sensors
23 In-car information presentation device

Claims (8)

A deviation determining means which the vehicle is judged whether the deviation tendency from the driving lane, the host vehicle Ru is determined that the departure tendency from the traffic lane, in a direction to avoid the deviation from the travel lane of the vehicle a longitudinal force control amount calculating means for calculating the braking-driving force control amount of each wheel as the yaw moment is generated, the braking-driving force control means according to the braking and driving force control amount for controlling the longitudinal force of each wheel and, with a,
When the braking / driving force control amount calculation means can calculate a plurality of braking / driving force control amounts that generate the yaw moment, the braking / driving force that can be calculated in plural is used as the braking / driving force control amount of each wheel. A lane departure prevention apparatus characterized by calculating a braking / driving force control amount such that a difference in braking / driving force between front and rear wheels is reduced among the control amounts .   The lane departure prevention device according to claim 1, wherein the braking / driving force control means can individually control at least the braking force of the left and right wheels. When the braking / driving force control amount calculation means can calculate a plurality of braking / driving force control amounts that generate the yaw moment, the braking / driving force that can be calculated in plural is used as the braking / driving force control amount of each wheel. of the control amount, that a departing direction from the driving lane of the host vehicle braking force generated in the front wheel on the opposite side, and calculates a so that a longitudinal force control quantity braking force will occur in the left and right rear wheels of the vehicle The lane departure prevention apparatus according to claim 2. Comprising a slip state judging means for a predetermined wheel to determine whether or not the slip state,
The braking / driving force control amount calculating means can calculate a plurality of braking / driving force control amounts for generating the yaw moment when the slip state determining means determines that the predetermined wheel is in a slip state. The braking / driving force control amount for each wheel is calculated such that the braking / driving force control amount for the predetermined wheel is reduced among the plurality of braking / driving force control amounts that can be calculated. lane departure prevention apparatus according to any one of claims 1 to 3. The braking / driving force control amount calculating means can calculate a plurality of braking / driving force control amounts for generating the yaw moment when the slip state determining means determines that the predetermined wheel is in a slip state. the as longitudinal force control amount of each wheel, of the plurality calculable braking-driving force control amount, limiting the longitudinal force control amount of the reference wheel, the reference wheel vehicle longitudinal direction in symmetrical wheels Calculate the braking / driving force control amount by adding the limit to the braking / driving force control amount,
When the slip state determination means determines that the predetermined wheel is not in the slip state, a plurality of braking / driving force control amounts for generating the yaw moment can be calculated. As described above, the braking / driving force control amount is calculated so that the braking force is generated only in the front and rear wheels on the side opposite to the direction of departure from the traveling lane of the host vehicle among the plurality of braking / driving force control amounts that can be calculated. The lane departure prevention apparatus according to claim 4. A deviation determining means which the vehicle is judged whether the deviation tendency from the driving lane, the host vehicle Ru is determined that the departure tendency from the traffic lane, in a direction to avoid the deviation from the travel lane of the vehicle a longitudinal force control amount calculating means for calculating the braking-driving force control amount of each wheel as the yaw moment is generated, the braking-driving force control means according to the braking and driving force control amount for controlling the longitudinal force of each wheel And damping force control means for increasing the damping force of the suspension device when the difference between the braking / driving force control amounts of the left and right wheels calculated by the braking / driving force control amount calculation means is larger than a predetermined value. A lane departure prevention device characterized by this. The deviation determining means determines that when lateral displacement with respect to the traffic lane in the future of the vehicle is estimated from the running state of the vehicle is equal to or higher than a predetermined lateral displacement limit value, the vehicle is in a deviation tendency from the traffic lane lane departure prevention apparatus according to any one of claims 1 6, characterized by. The braking-driving force control amount calculating means calculates a larger target yaw moment is great difference between the lateral displacement and lateral displacement limit value for the traffic lane in the future of the vehicle is estimated from the running state of the vehicle, its a lane departure prevention apparatus according to any one of claims 1, characterized in that to calculate the braking and driving force control amount of each wheel based on the target yaw moment 7.

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