JP3832304B2 - 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 of a host vehicle 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]
However, when an attempt is made to construct a lane departure prevention device that controls the braking / driving force of each wheel to generate a yaw moment in this way, for example, if a steep curve appears in the traveling lane of the host vehicle, The amount of lateral deviation of the traveling position of the host vehicle with respect to the reference position is increased, and a large yaw moment is generated by the braking / driving force control, which may cause the passenger to feel uncomfortable.
[0005]
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the prior art, and prevents the passenger from feeling uncomfortable when controlling the braking / driving force to prevent lane departure. It is an object of the present invention to provide a travel lane departure prevention device.
[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 includes a traveling state detection unit that detects a traveling state of the host vehicle, and a traveling state of the host vehicle that is detected by the traveling state detection unit. A deviation amount estimating means for calculating a deviation amount estimated value from the traveling lane of the host vehicle in the future, and a deviation from the traveling lane of the own vehicle based on the deviation amount estimated value calculated by the deviation amount estimating means. a longitudinal force control amount calculating means for calculating the braking-driving force control amount of each wheel as the yaw moment is generated in a direction to avoid, the deviation based on the deviation amount estimation value calculated by the deviation amount estimating means in the deceleration control amount calculating means for calculating a braking force control amount of each wheel causes decelerating the vehicle so that the amount estimated value becomes smaller, deviation estimation value calculated by the deviation amount estimating means first set value or more In some cases, the vehicle is a traveling vehicle And determining departure tendency determining means to be in a departure tendency from the host vehicle is determined to be in the departure tendency from the traffic lane in the departure tendency determining means, deviation estimation value calculated by the deviation amount estimating means If it is more than the second set value, each in accordance with the total value of the longitudinal force control amount longitudinal force control amount calculated by the calculation unit and the deceleration control amount calculating means braking force control amount calculated by A braking / driving force control amount calculated by the braking / driving force control amount calculating means when the braking / driving force of the wheel is controlled and the estimated deviation amount calculated by the departure amount estimating means is smaller than a second set value. And a braking / driving force control means for controlling the braking / driving force of each wheel only according to the above.
[0010]
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 traveling state detecting unit calculates a curvature of the traveling lane of the host vehicle, and the deceleration control amount calculating unit includes: The second set value is decreased as the curvature of the traveling lane of the host vehicle detected by the traveling state detecting means increases.
The invention according to claim 3 is the lane departure prevention apparatus according to claim 1 or 2 , wherein the braking / driving force control amount calculation means is the travel of the host vehicle detected by the travel state detection means. and a large value of the target yaw moment larger the difference between the lateral displacement and lateral displacement limit value for the traffic lane in the future of the vehicle is estimated from the state, the braking-driving force control amount of each wheel on the basis of the target yaw moment Is calculated.
[0011]
According to a fourth aspect of the present invention, in the lane departure prevention apparatus according to any one of the first to third aspects of the present invention, the apparatus includes a curvature calculation unit that calculates a curvature of a traveling lane of the host vehicle, and the braking / driving force control unit includes: As the curvature of the traveling lane of the host vehicle calculated by the curvature calculation means increases, the braking force control amount calculated by the braking / driving force control means decreases and the braking control amount calculated by the deceleration control amount calculation means. The power control amount is increased.
Further, the invention according to claim 5 is the lane departure prevention apparatus according to any one of claims 1 to 3, further comprising a travel speed detecting means for detecting a travel speed of the host vehicle, wherein the braking / driving force control means includes: The greater the traveling speed of the host vehicle detected by the traveling speed detecting means, the smaller the braking force control amount calculated by the braking / driving force control means and the braking force control calculated by the deceleration control amount calculating means. It is characterized by increasing the amount.
The invention according to claim 6, in the lane departure prevention apparatus is an invention described in any one of claims 1 to 5, wherein the braking-driving force control means individually braking force of at least the right and left wheel control It is possible to do.
[0012]
【The invention's effect】
Therefore, in the lane departure prevention apparatus is the invention according to claim 1, in example embodiment, steep curves appear in front of the vehicle, when the deviation amount estimation value of the vehicle becomes large, decelerating the host vehicle As a result, the estimated deviation amount can be reduced, and the yaw moment generated by the braking / driving force control can be reduced.
[0015]
Et al is, if example embodiment, a curve ahead of the host vehicle travel lane is slowly, until deviation estimation value of the vehicle is small, never result in decelerating the vehicle, without causing discomfort to the occupants It will end.
[0016]
Further, in the lane departure prevention apparatus is the invention according to claim 2, in example embodiment, even with a small deviation estimated amount of the vehicle, when the steep curve ahead of the host vehicle appears the own vehicle is decelerated Thus, an increase in the estimated deviation amount of the host vehicle can be prevented.
Further, in the lane departure prevention apparatus is the invention according to claim 3, in example embodiment, for example, as the difference between the lateral displacement and lateral displacement limit value increases by increasing the target yaw moment, the deviation from the travel lane It can be avoided reliably.
[0017]
Further, in the lane departure prevention apparatus is the invention according to claim 6, the yaw moment generated in the vehicle by individually controlling the braking force of the left and right wheel, coincides with the target yaw moment to the lane departure avoidance direction Thus, deviation from the driving lane can be avoided and the driver's steering operation is not affected, so that the driver does not feel uncomfortable.
[0018]
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.
[0019]
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.
[0020]
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.
[0021]
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.
[0022]
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.
[0023]
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), 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.
[0024]
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.
[0025]
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.
[0026]
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).
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
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 smaller between 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 either.
[0031]
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.
[0032]
Next, the process proceeds to step S8, and it is determined whether or not to decelerate the host vehicle as lane departure prevention control. Specifically, first, a value obtained by subtracting the lateral displacement limit value Xc from the estimated future lateral displacement XS calculated in step S3 is set using a function that gradually decreases with an increase in the curvature β of the travel lane shown in FIG. When it is equal to or greater than the threshold value Xa, it is determined that the host vehicle is to be decelerated and the deceleration control operation flag Fgs is set. Otherwise, it is determined that the host vehicle is not to be decelerated and the deceleration control operation flag is set. Reset Fgs.
[0033]
Thus, in this embodiment, when the value obtained by subtracting the lateral displacement limit value Xc from the estimated lateral displacement XS in the future is equal to or greater than the threshold value Xa, it is determined that the host vehicle is decelerated and the deceleration control operation flag is set. In order to set Fgs, for example, the traveling lane curve ahead of the host vehicle is gentle and the host vehicle is not decelerated until the estimated lateral displacement XS is small in the future, without causing the passengers to feel uncomfortable. That's it.
[0034]
Further, as shown in FIG. 4, the threshold value Xa decreases as the curvature β of the traveling lane of the host vehicle increases. For example, when a sharp curve appears in front of the host vehicle, the threshold value Xa is Since the deceleration control operation flag Fgs is set to be smaller than the estimated lateral displacement XS, the host vehicle is decelerated to prevent the estimated lateral displacement XS from increasing.
[0035]
In step S9, 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.
[0036]
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.
[0037]
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 S10, and the left and right wheel target braking fluid pressure differences ΔPSF and ΔPSR of the front and rear wheels are calculated. Specifically, when the departure determination flag FLD is in the reset state, the left and right wheel target braking fluid pressure differences ΔPSF and ΔPSR are set to “0”.
[0038]
On the other hand, even when the departure determination flag FLD is set, the cases are classified according to the magnitude of the target yaw moment Ms calculated in step S9. That is, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms1, a difference is generated only in the braking force of the rear left and right wheels, and the absolute value | Ms | of the target yaw moment is equal to or greater than the predetermined value Ms1. Sometimes a difference is generated in the braking force between the front, rear, left and right wheels. Accordingly, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms1, the front left and right wheel target braking fluid pressure difference ΔPSF is “0”, and the rear left and right wheel target braking fluid pressure difference ΔPSR is given by the following three equations. It is done. Similarly, when the absolute value | Ms | of the target yaw moment is equal to or greater than the predetermined value Ms1, the front left and right wheel target braking fluid pressure difference ΔPSF is given by the following formula 4, and the rear left and right wheel target braking fluid pressure difference ΔPSR is given by the following formula 5. . In the equation, T is a tread (the same applies to the front and rear wheels), KbF and KbR are conversion coefficients for converting braking force into braking fluid pressure, and are determined by brake specifications.
[0039]
ΔPSR = 2 × KbR × | Ms | / T (3)
ΔPSF = 2 × KbF × (| Ms | −Ms1) / T (4)
ΔPSR = 2 × KbR × | Ms1 | / T (5)
Further, when the absolute value | Ms | of the target yaw moment is equal to or larger than the upper limit value Ms2 (> predetermined value Ms1), the front left and right wheel target braking fluid pressure difference ΔPSF is the following six equations, and the rear left and right wheel target braking fluid pressure difference ΔPSR is It is given by Equation 7.
[0040]
ΔPSF = 2 × KbF × (Ms2−Ms1) / T (6)
ΔPSR = 2 × KbR × Ms1 / T (7)
As described above, in the present embodiment, since the upper limit value is set for the front left and right wheel target braking fluid pressure difference ΔPSF, the yaw moment generated by the braking / driving force control can be reliably reduced, and the passenger does not feel uncomfortable.
[0041]
Next, the process proceeds to step S11 where a target deceleration amount is calculated and set. Here, since the target deceleration amount Pg is set only when the departure determination flag FLD is set, when the departure determination flag FLD is set, it is set according to the traveling speed V shown in FIG. The proportional coefficient Kv, the estimated future lateral displacement XS calculated in step S3, the lateral displacement limit value Xc used as the alarm judgment threshold in step S6, and the deceleration control operation flag Fgs in step S8. The target deceleration amount Pg is calculated according to the following eight equations using the threshold value Xa used as the determination threshold value.
[0042]
Pg = -Kv * (XS-Xc-Xa) (8)
When the departure determination flag FLD is in the reset state, the target deceleration amount Pg is set to “0”.
Next, the process proceeds to step S12, 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.
[0043]
On the other hand, even when the deviation determination flag FLD is set, the case is divided according to the magnitude of the target yaw moment Ms calculated in step S9 and the deceleration control operation flag Fgs set in step S8. . That is, when the deceleration control operation flag Fgs is in a reset state and 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 to each of the wheel cylinders 6FL to 6RR is performed. The fluid pressure Psi is given by the following nine equations for adding the left and right wheel target braking fluid pressure differences ΔPSF and ΔPSR calculated in step S10 to the right wheel side.
[0044]
PSFL = Pm
PSFR = Pm + ΔPSF
PSRL = PmR
PSRR = PmR + ΔPSR (9)
On the other hand, when the deceleration control operation flag Fgs is in a reset state and the target yaw moment Ms is a positive value, that is, when the host vehicle is about to depart from the lane to the right, The target braking fluid pressure Psi is given by the following 10 equations for adding the left and right wheel target braking fluid pressure differences ΔPSF and ΔPSR calculated in step S10 to the left wheel side.
[0045]
PSFL = Pm + ΔPSF
PSFR = Pm
PSRL = PmR + ΔPSR
PSRR ＝ PmR ……… (10)
As described above, in the present embodiment, the yaw moment generated in the vehicle by individually controlling the braking force of the left and right wheels is made to coincide with the target yaw moment Ms in the lane departure avoidance direction to deviate from the traveling lane. Therefore, the driver's steering operation is not affected and the driver does not feel uncomfortable.
[0046]
Further, when the deceleration control operation flag Fgs is set and 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 to each of the wheel cylinders 6FL to 6RR is performed. The fluid pressure Psi is determined by adding the left and right wheel target braking fluid pressure differences ΔPSF and ΔPSR calculated in step S10 to the right wheel side and the target deceleration amount Pg calculated in step S11 from the vehicle specifications. The value obtained by multiplying the proportional coefficient Kg by all the wheels is given by the following 11 equations.
[0047]
PSFL = Pm + Kg × Pg
PSFR = Pm + Kg × Pg + ΔPSF
PSRL = PmR + Kg × Pg
PSRR = PmR + Kg × Pg + ΔPSR (11)
On the other hand, when the deceleration control operation flag Fgs is in the set state and the target yaw moment Ms is a positive value, that is, when the own vehicle is about to depart from the lane to the right, The target braking fluid pressure Psi and the left and right wheel target braking fluid pressure differences ΔPSF, ΔPSR calculated in step S10 are added to the left wheel side, and the target deceleration amount Pg calculated in step S11 is determined from vehicle specifications. The value obtained by multiplying the proportional coefficient Kg by all the wheels is given by the following 12 equations.
[0048]
PSFL = Pm + Kg × Pg + ΔPSF
PSFR = Pm + Kg × Pg
PSRL = PmR + Kg × Pg + ΔPSR
PSRR = PmR + Kg × Pg ……… (12)
Next, the process proceeds to step S13 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 drive torque TrqDS when the departure determination flag FLD is set is determined based on the target brake fluid pressure differences ΔPSF and ΔPSR of the front and rear wheels and the values of all the wheels from the value corresponding to the accelerator opening Acc read in step S1. The value corresponding to the sum of the target deceleration amount Pg is reduced. That is, the value corresponding to the accelerator opening Acc is a driving torque for accelerating the host vehicle according to the accelerator opening Acc, and the target braking fluid pressure differences ΔPSF, ΔPSR of the front and rear wheels and the target deceleration amount Pg of all the wheels Is a braking torque generated by the sum of the target braking fluid pressure differences ΔPSF, ΔPSR and the target deceleration amount Pg of all the wheels. Accordingly, when the departure determination flag FLD is set and the lane departure prevention control is performed, the engine torque is increased by the braking torque generated by the sum of the target braking fluid pressure differences ΔPSF, ΔPSR and the target deceleration amount Pg of all the wheels. Will be reduced. 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.
[0049]
Next, the process proceeds to step S14, where the target braking fluid pressure of each wheel calculated in step S12 is output to the braking fluid pressure control circuit 7, and the target driving of the driving wheel calculated in step S13 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. The braking force of each wheel is controlled so that is achieved. 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. Further, in this embodiment, while the lane departure prevention control is being performed, the engine output torque is reduced and the traveling speed of the host vehicle is reduced. Therefore, it is possible to more safely prevent the lane departure. It becomes.
[0050]
In this embodiment, when the departure determination flag FLD is set, the target deceleration amount Pg is calculated based on a value obtained by subtracting the lateral displacement limit value Xc and the threshold value Xa from the estimated lateral displacement XS in the future. When the value obtained by subtracting the lateral displacement limit value Xc from the estimated lateral displacement XS in the future becomes equal to or greater than the threshold value Xa, it is determined that the host vehicle needs to be decelerated, and the deceleration control operation flag Fgs is set. Since the braking force of all the wheels is controlled so that the target deceleration amount Pg is achieved, for example, when a steep curve appears in front of the host vehicle as shown in FIG. The host vehicle is decelerated, the estimated lateral displacement XS is reduced, and the yaw moment generated by the braking / driving force control is reduced, so that the passenger does not have to feel uncomfortable. Incidentally, FIG. 7b shows a case where a sharp curve appears in front of the host vehicle, and the host vehicle is not decelerated even though the estimated lateral displacement XS is large in the future, and a large yaw moment is generated by the braking force control. This will cause the passenger to feel uncomfortable.
[0051]
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. 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 arithmetic processing of FIG. 8, steps S8, S9, S11 and S12 of the arithmetic processing of FIG. 2 are changed to steps S8 ′, S9 ′, S11 ′ and S12 ′.
[0052]
Of these, in step S8 ′, the difference between the estimated lateral displacement XS and the lateral displacement limit value Xc in the future is reduced by the deceleration of the host vehicle, and the yaw is set in a direction to avoid the departure from the traveling lane of the host vehicle. The amount to be reduced by generating a moment is calculated. Specifically, the sharing rate Hg of the deceleration control set using a function that gradually increases with the increase in the curvature β of the traveling lane and the increase in the traveling vehicle speed V shown in FIG. 9, and the future calculated in step S3. Using the estimated lateral displacement XS and the lateral displacement limit value Xc, the deceleration control sharing amount ΔXg and the yaw moment control sharing amount ΔXy are calculated according to the following equation (13).
[0053]
ΔXg = Hg × (XS−Xc)
ΔXy = (1−Hg) × (XS−Xc) (13)
Next, the process proceeds to step S9 ′ to calculate and set the target yaw moment. Here, as in the first embodiment, 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, from the vehicle specifications. Using the proportional coefficient K1 determined, the proportional coefficient K2 set according to the traveling speed V shown in FIG. 5 and the yaw moment control share amount ΔXy calculated in step S8 ′, the target yaw The moment Ms is calculated.
[0054]
Ms = −K1 × K2 × ΔXy ……… (14)
When the departure determination flag FLD is in the reset state, the target yaw moment Ms is set to “0”.
In step S11 ′, a target deceleration amount is calculated and set. Here, as in the first embodiment, the target deceleration amount Pg is set only when the departure determination flag FLD is set. Therefore, when the departure determination flag FLD is set, FIG. The target deceleration amount Pg is calculated according to the following equation (15) using the proportionality coefficient Kv set according to the travel speed V shown and the deceleration control share amount ΔXg calculated in step S8 ′.
[0055]
Pg = Kv × ΔXg ……… (15)
When the departure determination flag FLD is in the reset state, the target deceleration amount Pg is set to “0”.
Next, the process proceeds to step S12 ′, and the target braking fluid pressure Psi for each wheel is calculated. Here, as in the first embodiment, 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, the departure determination flag FLD is reset. In this state, the target brake fluid pressure PSFL, PSFR to the wheel cylinders 6FL, 6FR of the front left and right wheels 5FL, 5FR are both the master cylinder pressure Pm, and the target brake to the wheel cylinders 6RL, 6RR of the rear left and right wheels 5RL, 5RR is set. The fluid pressures PSRL and PSRR are both the rear wheel master cylinder pressure PmR.
[0056]
On the other hand, even when the departure determination flag FLD is set, the cases are classified according to the magnitude of the target yaw moment Ms calculated in the step S9 ′. Accordingly, when the target yaw moment Ms is a negative value, that is, when the host vehicle is about to deviate to the left, the target braking fluid pressure Psi to each of the wheel cylinders 6FL to 6RR is given by the following equation (16).
[0057]
PSFL = Pm + Kg × Pg
PSFR = Pm + Kg × Pg + ΔPSF
PSRL = PmR + Kg × Pg
PSRR = PmR + Kg × Pg + ΔPSR (16)
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 given by the following equation (17). .
[0058]
PSFL = Pm + Kg × Pg + ΔPSF
PSFR = Pm + Kg × Pg
PSRL = PmR + Kg × Pg + ΔPSR
PSRR = PmR + Kg × Pg ……… (17)
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. A value obtained by subtracting the lateral displacement limit value Xc and the threshold value Xa from the estimated lateral displacement XS in the future, and a function that gradually increases with the increase in the curvature β of the travel lane and the increase in the travel vehicle speed V shown in FIG. The target yaw moment Ms and the target deceleration amount Pg are calculated on the basis of the deceleration control sharing ratio Hg set by using the braking control of each wheel so that the target yaw moment Ms and the target deceleration amount Pg are achieved. Is done. Thus, for example, when the yaw moment of the host vehicle is large due to high speed traveling on a sharp curve, the curvature β and the traveling speed V of the traveling lane increase, and the yaw moment control share amount ΔXy is calculated to be small and the deceleration is reduced. Since the control sharing amount ΔXg is calculated to be large, even if the estimated lateral displacement XS is small in the future, the host vehicle is decelerated and the yaw moment generated by the braking / driving force control is reduced, so that the passenger does not feel uncomfortable. .
[0059]
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. The deviation amount estimation means is configured, and steps S9, S10 and S9 ′ of the calculation processes of FIGS. 2 and 8 constitute the braking / driving force control amount calculation means, and steps S8, S11 and of the calculation processes of FIGS. S11 ′ constitutes a deceleration control amount calculation means, the braking fluid pressure control circuit 7 and the drive torque control unit 12 in FIG. 1 constitute braking / driving force control means, and step S9 ′ of the arithmetic processing in FIG. It constitutes quantity calculation 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 a control map used for the arithmetic processing in FIG. 2;
FIG. 6 is a control map used for the arithmetic processing of FIG.
7 is an explanatory diagram of the operation of the arithmetic processing in FIG. 2. FIG.
FIG. 8 is a flowchart showing a second embodiment of information calculation processing executed in the braking / driving force control unit of FIG. 1;
FIG. 9 is a control map used in the arithmetic processing of FIG.
[Explanation of symbols]
6FL to 6RR are wheel cylinders 7, braking fluid pressure control circuit 8, braking / driving force control unit 9, engine 12, driving torque control unit 13, CCD camera 14, camera controller 15, acceleration sensor 16, yaw rate sensor 17, master cylinder pressure Sensor 18 Accelerator opening sensor 19 Steering angle sensor 20 Direction indication switches 22FL-22RR Wheel speed sensor 23 In-car information presentation device

Claims (6)

Driving state detecting means for detecting the driving state of the host vehicle, and deviation amount estimation for calculating a deviation amount estimated value from the driving lane of the host vehicle in the future based on the driving state of the host vehicle detected by the driving state detecting unit. And a braking / driving force control amount for each wheel so that a yaw moment is generated in a direction avoiding the departure from the traveling lane of the host vehicle based on the estimated deviation value calculated by the deviation amount estimation means. calculating a braking-driving force control amount calculating section, a braking force control amount of each wheel causes decelerating the host vehicle such that the deviation estimation value is decreased based on the deviation amount estimation value calculated by the deviation amount estimating means for A decelerating control amount calculating means, and a deviating tendency determining means for determining that the host vehicle is deviating from the traveling lane when the estimated deviating amount calculated by the deviating amount estimating means is greater than or equal to a first set value; The departure tendency determination means If it is determined that the vehicle is in a deviation tendency from the traffic lane, when the deviation amount estimation value calculated by the deviation amount estimating means is equal to or greater than the second set value, in the braking-driving force control amount calculating means The deviation amount calculated by the deviation amount estimation means by controlling the braking / driving force of each wheel according to the total value of the calculated braking / driving force control amount and the braking force control amount calculated by the deceleration control amount calculation means. When the estimated value is smaller than the second set value, the braking / driving force control means for controlling the braking / driving force of each wheel according to only the braking / driving force control amount calculated by the braking / driving force control amount calculating means ; A lane departure prevention device characterized by comprising: The traveling state detection means calculates the curvature of the traveling lane of the host vehicle,
2. The lane departure prevention device according to claim 1 , wherein the deceleration control amount calculation unit decreases the second set value as the curvature of the traveling lane of the host vehicle detected by the traveling state detection unit increases. . The braking / driving force control amount calculating means increases the target as the difference between the lateral displacement and the lateral displacement limit value of the future own vehicle estimated from the running state of the own vehicle detected by the running state detecting means increases. The lane departure prevention apparatus according to claim 1 or 2 , wherein the yaw moment is a large value, and the braking / driving force control amount of each wheel is calculated based on the target yaw moment. A curvature calculating means for calculating the curvature of the traveling lane of the own vehicle;
The braking / driving force control means decreases the braking force control amount calculated by the braking / driving force control means and increases the deceleration control amount as the curvature of the traveling lane of the host vehicle calculated by the curvature calculation means increases. The lane departure prevention apparatus according to any one of claims 1 to 3, wherein the braking force control amount calculated by the calculation means is increased. A travel speed detecting means for detecting the travel speed of the host vehicle;
The braking / driving force control means decreases the braking force control amount calculated by the braking / driving force control means as the traveling speed of the host vehicle detected by the traveling speed detection means increases, and calculates the deceleration control amount. The lane departure prevention apparatus according to any one of claims 1 to 3, wherein a braking force control amount calculated by the means is increased. The braking-driving force control means, the lane departure prevention apparatus according to claims 1, characterized in that it individually controls the braking force of at least the left and right wheels in any one of 5.

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