JP4492321B2 - Lane departure prevention device - Google Patents

Description

  The present invention relates to a lane departure prevention device that prevents a departure when a host vehicle is about to depart from a traveling lane during traveling.

  Conventionally, as this type of technology, for example, when the host vehicle tends to deviate from the traveling lane, a braking force actuator is used according to the lateral deviation amount that is the distance from the reference position of the traveling lane to the traveling position of the host vehicle. There has been proposed a control system that prevents a deviation from the traveling lane of the host vehicle by applying a braking force to a wheel on the opposite side to the departure direction of the left and right wheels (see, for example, Patent Document 1). ).

Also, in this way, in the case where the difference in braking force is applied to the left and right wheels to prevent lane departure, the driving force and the braking force are applied when the driving force is applied by the driver's operation. For example, in a state where the driver is operating the accelerator pedal, one of the driving force and the control for avoiding deviation is given priority. It has been proposed (see, for example, Patent Document 2).
JP 2000-33860 A JP 2003-306135 A

  As described above, when the accelerator pedal operation is performed by the driver and the driving force is generated, the braking force control for preventing lane departure or the generation of the driving force is not performed. Interference with the braking force can be avoided. However, suppressing the lane departure prevention control when the accelerator pedal operation is being performed in a lane departure tendency means that the lane departure prevention control is being performed while the accelerator pedal operation is being performed. The deviation avoidance effect is also reduced. Conversely, when the generation of driving force is suppressed, for example, when there is a tendency to deviate from the lane, such as when changing lanes, there is sufficient driving force even though the accelerator pedal is being operated. On the contrary, the yaw moment is generated without generating, and the driver may feel uncomfortable.

In order to avoid this, for example, if the control amount for preventing lane departure is suppressed, the feeling of deceleration given to the driver can be suppressed. However, as described above, suppressing the control amount for preventing lane departure means that a sufficient control effect for preventing lane departure cannot be obtained.
Therefore, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and prevents lane departure even when driving force is generated and braking force is generated by lane departure prevention control. An object of the present invention is to provide a lane departure prevention device capable of accurately performing control for the vehicle.

In order to achieve the above object, the lane departure prevention apparatus according to the present invention detects whether or not the vehicle has a lane departure tendency by the departure detection means, and detects that the vehicle is in a lane departure tendency. The vehicle behavior of the host vehicle is controlled by the control means in a direction that avoids deviation from the traveling lane of the host vehicle. At this time, when the host vehicle tends to depart from the lane, the braking / driving force generated by the braking / driving force generating means for generating the braking / driving force according to the requested braking / driving force required by the driver's operation is In other words, between the braking / driving force generated by the departure avoidance control by the departure avoiding control means and the braking / driving force corresponding to the requested braking / driving force required by the operation of the driver. The braking / driving force component acting in the direction of inhibiting the braking / driving force is detected as a repulsive force, and the braking / driving force generated by the braking / driving force generating means is suppressed by an amount corresponding to the repulsive force.

According to the lane departure prevention apparatus according to the present invention, the braking / driving force component acting in the direction of interfering with each other between the braking / driving force generated in accordance with the departure avoidance control and the braking / driving force according to the requested driving force is obtained. The braking / driving force generated by the braking / driving force generating means is detected because the braking / driving force generated by the braking / driving force generating means is suppressed by an amount equivalent to the repulsive force when detected as a repulsive force and tends to depart from the lane And the braking / driving force generated by the departure avoidance control by the departure avoidance control means can be avoided, and the control effect by the departure avoidance control can be ensured and the required amount of braking / driving force can be satisfied. The braking / driving force can be secured.

Embodiments of the present invention will be described below.
FIG. 1 is a schematic vehicle configuration diagram showing an example of a lane departure prevention apparatus according to a first reference embodiment of the present invention.
This vehicle is a rear-wheel drive vehicle equipped with an automatic transmission and a conventional differential gear, and the braking device can control the braking force of the left and right wheels independently of the front and rear wheels.

  Reference numeral 1 in FIG. 1 is a brake pedal, 2 is a booster, 3 is a master cylinder, and 4 is a reservoir. Usually, the brake fluid pressure increased by the master cylinder 3 in accordance with the amount of depression of the brake pedal 1 by the driver. Is supplied to the wheel cylinders 6FL to 6RR of the wheels 5FL to 5RR. A braking 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.

  The brake fluid pressure control circuit 7 uses a brake fluid pressure control circuit used for, for example, anti-skid control or 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 vehicle state control unit 8 described later.

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, but the drive torque command value is input from the vehicle state control unit 8 described above. When this is done, the drive wheel torque is controlled with reference to the drive torque command value.

  In addition, the vehicle includes a monocular camera 13 and a camera controller that are configured by a CCD camera or the like as a front external field recognition sensor for detecting the position of the host vehicle in the travel lane for determining departure from the travel lane of the host vehicle. 14 is provided. The camera controller 14 detects, for example, a lane marker such as a white line from a captured image in front of the host vehicle captured by the monocular camera 13 to detect a travel lane, and the yaw angle θ of the host vehicle with respect to the travel lane, that is, a travel lane. The vehicle direction, the lateral displacement X of the vehicle from the center of the traveling lane, the curvature β of the traveling lane, and the like can be calculated.

The camera controller 14 performs travel lane detection using a travel lane detection area for detecting lane markers and the like, and calculates the data for the detected travel lane. For example, a technique described in Japanese Patent Application Laid-Open No. 11-296660 can be used for detecting the traveling lane.
Specifically, lane markers such as white lines on both sides of the traveling lane in which the host vehicle is traveling are detected, and the traveling lane in which the host vehicle is traveling is detected using the lane marker. Here, if a lane marker such as a white line is detected (scanned) over the entire captured image, the calculation load is large and time is required. Therefore, a smaller detection area (so-called window) is set in an area where a lane marker is likely to exist, and the lane marker is detected in the detection area. In general, when the direction of the host vehicle with respect to the lane changes, the position of the lane marker displayed in the image also changes. For example, in Japanese Patent Laid-Open No. 11-296660, the direction of the host vehicle with respect to the lane is estimated from the steering angle δ, and the image The detection area is set in the area where the lane marker in the box will be projected.

  Then, for example, a filtering process that makes the boundary between the lane marker and the road surface stand out is performed, and a straight line that seems to be the boundary between the lane marker and the road surface is detected in each lane marker detection region, and one point (lane marker candidate point) on the straight line is detected as the lane marker. It is detected as a representative site. If the lane marker candidate points of each window obtained in this way are continued, it is possible to detect a traveling lane that is deployed ahead of the host vehicle.

  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 master. A master cylinder pressure sensor 17 that detects the 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 5FL Are provided with wheel speed sensors 22FL to 22RR for detecting a rotational speed of 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. It is output to the vehicle state control unit 8.

  Further, the yaw angle θ of the host vehicle with respect to the travel lane detected by the camera controller 14, the lateral displacement X of the host vehicle from the center of the travel lane, the curvature β of the travel lane, on the wheel axis controlled by the drive torque control unit 12 The driving torque Tw at is also output to the vehicle state control unit 8. If the detected vehicle traveling state data has left and right directions, the left direction is the positive direction. That is, the yaw rate φ, the lateral acceleration Yg, the steering angle δ, and the yaw angle θ are positive values when turning left, and the lateral displacement X is a positive value when deviating leftward from the center of the traveling lane.

  Also, a warning monitor 23 is provided in the vicinity of the driver's seat to warn the driver when a vehicle lane departure is detected by the vehicle state control unit 8. The monitor 23 has a built-in speaker for generating sound and buzzer sound, and issues a warning to the driver by display information and sound information.

  Next, the processing procedure of the arithmetic processing performed by the vehicle state control unit 8 will be described with reference to the flowchart of FIG. This arithmetic processing is executed by timer interruption every predetermined sampling time ΔT. 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.

  In this calculation process, first, in step S1, various data from the sensors, the controllers, and the control unit are read. Specifically, the longitudinal acceleration Xg, lateral acceleration Yg, yaw rate φ, wheel speed Vwi, accelerator opening Acc, master cylinder pressure Pm, steering angle δ, direction indication switch signal, camera controller 14 detected by the sensors. The yaw angle θ of the host vehicle relative to the travel lane from the vehicle, the lateral displacement X of the host vehicle from the center of the travel lane, the curvature β of the travel lane, and the drive torque Tw from the drive torque control unit 12 are read.

Next, the process proceeds to step S2, and a future estimated lateral displacement Xs is calculated as an estimated deviation value. Specifically, the yaw angle θ with respect to the travel lane of the host vehicle, the lateral displacement X of the host vehicle from the center of the travel lane, the curvature β of the travel lane, and the travel speed V of the host vehicle are read as follows. A future estimated lateral displacement Xs is calculated according to the equation (1).
Xs = Tt × V × (θ + Tt × V × β) + X (1)

  In Expression (1), Tt is the vehicle head time for calculating the forward gaze distance, and 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 depart from the driving lane or tend to deviate. .

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 that are non-driven wheels among the wheel speeds Vwi (i = FL to RR) read in step S1. .
Here, the case where the traveling speed V is calculated based on the front left and right wheel speeds VwFL, VwFR has been described. For example, the vehicle is equipped with ABS control means for performing known anti-skid control, When the anti-skid control is performed by the ABS control means, the estimated vehicle speed estimated in the process of the anti-skid control may be used.

Next, the process proceeds to step S3, and it is determined whether or not the host vehicle tends to deviate from the traveling lane. This determination is made according to the comparison result between the estimated future lateral displacement Xs as the deviation estimated value calculated in step S2 and the deviation determination threshold value Xc.
Specifically, when the estimated lateral displacement Xs and the departure determination threshold value Xc are Xs ≧ Xc, it is determined that the departure is left, and the departure determination flag FLD is set to “ON”. If Xs ≦ −Xc, it is determined that the vehicle deviates to the right, and the departure determination flag FLD is set to “ON”. Further, when neither Xs ≧ Xc nor Xs ≦ −Xc is satisfied, it is determined that there is no departure and the departure determination flag FLD is set to “OFF”.

  Here, the departure determination threshold value Xc is a constant, for example, a value obtained by subtracting a half value of the vehicle width L0 of the host vehicle from a half value of the traveling lane width L, for example, 0.8 [m]. Whichever is smaller can be used. The travel lane width L may be a fixed value (for example, a highway lane width of 3.35 [m]), or the vehicle travels by taking the position of the host vehicle from the map data as lane width information by navigation information or the like. You may make it change according to the road. In addition, the distance “L / 2−Xs” to the lane marking in the departure direction of the host vehicle detected by the infrastructure system based on a marker or the like embedded in the road can be obtained by road-to-vehicle communication or the like. In this case, this information may be used.

  Here, the lane departure determination is performed based on the departure determination threshold value Xc. For example, it is determined whether or not the driver has changed the lane, and the lane change situation is also taken into consideration. Then, a lane departure determination may be performed. Specifically, it is determined that the direction indicating switch 20 is operated based on the direction indicating switch signal from the direction indicating switch 20, and the direction indicated by the signal is specified from the sign of the estimated lateral displacement Xs. If it coincides with the departure direction, it is determined that the driver is intentionally changing the lane, and the departure determination flag FLD is changed to “OFF”. Conversely, if the direction specified by the direction indicating switch signal does not coincide with the departure direction specified from the estimated lateral displacement Xs, the departure determination flag FLD is not changed because there is a possibility of a lane departure. Even when the direction indicating switch 20 is not operated, it is determined that the driver is steering in the departure direction based on the steering angle δ from the steering angle sensor 19, and the steering angle δ is set in advance. If it is greater than or equal to the threshold value, it is determined that the driver intends to change lanes, and the departure determination flag FLD is changed to “OFF”.

  Next, the process proceeds to step S4 to calculate a target driving force. Here, the pseudo accelerator opening As, which is the accelerator opening corresponding to the final target driving force, is calculated. This pseudo accelerator opening As is calculated based on the accelerator opening Acc from the accelerator opening sensor 18 read in step S1 in accordance with the departure determination flag FLD set in step S3.

That is, as shown in FIG. 3, when the departure determination flag FLD is “ON”, the accelerator opening “Acc” when the departure determination flag FLD is “ON” is set to the initial value A _0. setting the value to be decreased gradually to zero from an initial value a ₀ of the accelerator opening as a pseudo accelerator opening as. Further, when the departure determination flag FLD is “OFF”, the departure determination flag FLD is gradually increased from the pseudo accelerator opening As at the time when the departure determination flag FLD is “OFF” until it coincides with the accelerator opening Acc sequentially read. If the value is set as the pseudo accelerator opening degree As and the pseudo accelerator opening degree As coincides with the accelerator opening degree Acc, thereafter, the accelerator opening degree Acc that is sequentially read is set as the pseudo accelerator opening degree As. That is, when it is not determined that the vehicle is departing from the lane, a driving force corresponding to the accelerator opening Acc is set as the target driving force, and when it is determined that the vehicle is departing from the lane, the pseudo accelerator is opened so that the target driving force gradually decreases and eventually becomes zero. The degree As is set.

In this way, when the pseudo accelerator opening As is calculated and the target driving force is specified, the process proceeds to step S5, and the target yaw moment Ms generated in the vehicle is calculated in order to suppress lane departure. Here, when the departure determination flag FLD is “OFF”, the target yaw moment is Ms = 0, and only when the departure determination flag FLD is “ON”, the estimated lateral displacement Xs calculated in step S2 is set. The target yaw moment Ms is calculated based on the deviation (that is, the deviation amount) between the deviation judgment threshold value Xc and the following equation (2) when Xs ≧ Xc, and next when Xs ≦ −Xc. The target yaw moment Ms is calculated with reference to equation (3). Here, the yaw moment in the counterclockwise direction is positive.
Ms = −K1 × K2 × Kas × (Xs−Xc) (2)
Ms = −K1 × K2 × Kas × (Xs + Xc) (3)

In the equation, K1 is a proportional coefficient determined from vehicle specifications, K2 is a proportional coefficient set according to the traveling speed V of the host vehicle, and Kas is set according to the pseudo accelerator opening As calculated in step S4. For example, the correction gain is set as shown in FIG.
In FIG. 4, the horizontal axis represents the pseudo accelerator opening As corresponding to the target driving force calculated in step S4, and the vertical axis represents the correction gain Kas, in order to avoid driving force and lane departure due to accelerator pedal operation. It is set to avoid interference with the braking force.

  That is, for example, as shown in FIG. 4, the correction gain Kas is set to 100 [%] in a region where the pseudo accelerator opening As is equal to or less than the first threshold value As1, and as the pseudo accelerator opening As increases. The correction gain Kas decreases in inverse proportion to this, and the correction gain Kas is set to 0 [%] in the region where the pseudo accelerator opening As is greater than or equal to the second threshold value As2, which is larger than the first threshold value As1. The That is, the correction gain Kas corresponds to the lane departure amount as the target yaw moment Ms when the pseudo accelerator opening degree As is small, that is, when it is determined that there is a lane departure tendency or when the accelerator pedal operation amount of the driver is small. The yaw moment is set to be calculated, and the yaw moment is set so as to generate a lane departure with certainty. On the contrary, when the pseudo accelerator opening As is large, that is, when it is determined that there is no tendency to depart from the lane, it is not necessary to generate the yaw moment, so that the target yaw moment Ms is reduced. Then, between the first threshold values As1 and As2, the yaw moment applied to the vehicle is reduced by decreasing the correction gain Kas in proportion to the increase in the pseudo accelerator opening degree As and gradually changing the target yaw moment Ms. The amount of fluctuation is limited to suppress sudden fluctuations in vehicle behavior.

When the target yaw moment Ms is calculated in this way, the process proceeds to step S6, and the target braking force is calculated. Specifically, the target brake fluid pressure Psi for each wheel is calculated based on the master cylinder pressure Pm read in step S1 and the target yaw moment Ms calculated in step S5.
First, with respect to the master cylinder pressure Pm read in step S1, when the rear wheel master cylinder pressure based on the front / rear braking force distribution is PmR, if the departure determination flag is FLD “OFF”, the front left / right The target braking fluid pressures PsFL and PsFR to the wheel cylinders 6FL and 6FR of the wheels 5FL and 5FR are both the master cylinder pressure Pm, and the target braking fluid pressures PsRL and PsRR to the wheel cylinders 6RL and 6RR of the rear left and right wheels 5RL and 5RR are Both are the rear wheel master cylinder pressure PmR.

On the other hand, when the departure determination flag LD is “ON”, the case is divided according to the magnitude of the target yaw moment Ms. That is, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms0, 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 greater than or equal to the predetermined value Ms0. Sometimes a difference is generated in the braking force between the front, rear, left and right wheels. Therefore, when the absolute value | Ms | of the target yaw moment is less than the predetermined value Ms0, 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 expressed by the following equation (4). Set by. T in equation (4) is a tread (assuming the same for 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.
ΔPsR = 2 × KbR × | Ms | / T (4)

Similarly, the front left and right wheel target braking fluid pressure difference ΔPsF when the absolute value | Ms | of the target yaw moment is equal to or greater than the predetermined value Ms0 is the following equation (5), and the rear left and right wheel target braking fluid pressure difference ΔPsR is 6).
ΔPsF = 2 × KbF × (| Ms | −Ms0) / T (5)
ΔPsR = 2 × KbR × Ms0 / T (6)
Here, the case where the front and rear wheels are respectively controlled has been described. However, for example, the control may be performed using only the front wheels. In this case, for example, ΔPsF = 2 × KbF × | Ms | / T And it is sufficient.

Accordingly, 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 to the wheel cylinders 6FL to 6RR is given by the following equation (7). It is done.
PsFL = Pm
PsFR = Pm + ΔPsF
PsRL = PmR
PsRR = PmR + ΔPsR (7)

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 expressed by the following equation (8). Given.
PsFL = Pm + ΔPsF
PsFR = Pm
PsRL = PmR + ΔPsR
PsRR = PmR (8)

  When the target braking force is calculated in this way, the process proceeds to step S7, and a control signal is output to the drive torque control unit 12 so as to generate the target driving force corresponding to the pseudo accelerator opening As calculated in step S4. The driving force corresponding to the pseudo accelerator opening degree As is generated. That is, as shown in FIG. 3, when the departure determination flag FLD is “OFF” and there is no lane departure tendency, a driving force corresponding to the accelerator opening degree Acc is generated, but the departure determination flag FLD is “ON”. In other words, when the vehicle tends to depart from the lane, a driving force smaller than the driving force corresponding to the accelerator opening degree Acc is generated.

  Next, the process proceeds to step S8, and the target brake fluid pressure of each wheel calculated in step S6 is output to the brake fluid pressure control circuit 7. When the departure determination flag FLD is “ON”, the warning monitor 23 is operated to notify that the vehicle is in a lane departure tendency. Then, the program returns to the main program.

Next, the operation of the first reference embodiment will be described.
When the host vehicle is traveling in the center of the travel lane, the estimated lateral displacement Xs calculated in step S2 satisfies neither Xs ≧ Xc nor Xs ≦ −Xc. “OFF” is set (step S3). Accordingly, since the departure determination flag FLD is “OFF”, the target yaw moment is set to Ms = 0, and no departure avoidance yaw moment is generated. Further, when the departure determination flag FLD is “OFF”, the accelerator opening degree Acc corresponding to the depression amount of the accelerator pedal is set as the pseudo accelerator opening degree As, so that it corresponds to the operation amount of the accelerator pedal of the driver. A target driving force is generated. At this time, no yaw moment is generated as described above, so that the vehicle behavior conforms to the driving operation of the driver.

From this state, the host vehicle tends to deviate to the left, the estimated lateral displacement Xs increases, and when Xs ≧ Xc, the deviation determination flag FLD is set to “ON” (step S3). Therefore, as shown in FIG. 3, the accelerator opening Acc at this point as an initial value A _0, the value gradually decreases from the initial value A ₀ is set as a pseudo accelerator opening As, eventually pseudo accelerator opening As = 0. As the pseudo accelerator opening As decreases, the correction gain Kas gradually increases from 0 [%] to 100 [%] as shown in FIG.

  As described above, the driving force according to the pseudo accelerator opening As is generated, and the target yaw moment Ms is calculated according to the correction gain Kas. On the other hand, the generated driving force gradually decreases and eventually becomes zero, and the driving force is reduced. On the other hand, the braking force control is performed so that the target yaw moment Ms gradually increases as the driving force decreases and eventually the target yaw moment Ms corresponding to the lane departure amount is generated.

  In other words, in a state where a lane departure is determined and a braking force is generated to generate the target yaw moment Ms for avoiding this, the driving force is reduced even when the accelerator pedal is being operated. Since the driving force accompanying the operation of the accelerator pedal and the braking force for avoiding departure do not interfere with each other, sufficient yaw moment necessary for departure from the lane can be generated. A sufficient control effect by the control for avoidance can be obtained.

At this time, since the driving force is gradually reduced and the yaw moment is gradually generated, the driving force can be ensured while avoiding lane departure.
Then, when the target yaw moment Ms is generated or the driver recovers from the departure tendency by performing a steering operation or the like, and the departure determination flag FLD is “OFF”, the pseudo accelerator opening degree As is sequentially read. Gradually increase to match Acc. For this reason, when the departure determination flag FLD is “OFF”, the target yaw moment Ms gradually decreases accordingly, eventually becoming zero, and conversely, the driving force actually generated with respect to the operation amount of the target accelerator pedal. The driving force corresponding to the amount of operation of the accelerator pedal is generated.

  As described above, when the yaw moment is generated due to the tendency to depart from the lane, the driving force corresponding to the operation amount of the accelerator pedal is not generated, but the driving force is reduced and the target yaw moment Ms is secured on the contrary. Therefore, it is possible to avoid the interference between the braking force and the driving force for generating the target yaw moment Ms, and to obtain a sufficient control effect by the control for avoiding deviation.

  Further, at this time, when it is determined that the vehicle tends to deviate from the lane, the driving force corresponding to the operation amount of the accelerator pedal is gradually decreased and the target yaw moment Ms is gradually increased. When recovered, the driving force is gradually increased and the target yaw moment Ms is gradually decreased. Therefore, it can be avoided that the driver feels uncomfortable due to large changes in driving force and braking force. Furthermore, at the start of yaw moment generation, the yaw moment can be generated while securing the driving force, and at the end of yaw moment generation, the driving force can be recovered while securing the yaw moment. Interference can be avoided.

  At this time, as shown in FIG. 3, when the departure determination flag FLD is “OFF” and the pseudo accelerator opening As is increased to the accelerator opening Acc, the pseudo accelerator opening As is quickly changed. For example, when the vehicle recovers from the lane departure, the driving force is quickly recovered, and conversely, by suppressing the generation of the yaw moment, it is possible to avoid the yaw moment from acting despite the recovery from the lane departure. . In addition, by gradually reducing the pseudo accelerator opening degree As at the beginning of the lane departure, for example, when the intention is to temporarily deviate from the lane, the driving force is avoided from being reduced more than necessary. Thereafter, when the vehicle recovers from the lane departure tendency, the driving force can be quickly recovered.

In the first reference embodiment , as shown in FIG. 3, the case where the pseudo accelerator opening degree As is reduced to zero when it is determined that the vehicle tends to deviate from the lane has been described. It is not necessary to reduce to the accelerator opening degree corresponding to the target driving force to such an extent that the braking force and the driving force for generating the yaw moment for avoiding the deviation do not interfere with each other.

Next, an embodiment of the present invention will be described.
This embodiment of the present invention is the same as that of the first reference embodiment except that the processing procedure of the arithmetic processing executed by the vehicle state control unit 8 is different, so detailed description of the same part will be omitted.
In the embodiment of the present invention , the arithmetic processing is performed according to the procedure shown in the flowchart of FIG.
First, in step S11, various data are read in the same manner as in step S1 of FIG. 2 described above, and a driver required driving force (hereinafter also referred to as required driving force) τm corresponding to the accelerator opening Acc is calculated. .

Next, the process proceeds to step S12, where the estimated lateral displacement Xs is calculated in the same manner as in the first reference embodiment , and then a lane departure determination is performed (step S13).
And when it transfers to step S14 and the braking force for obtaining the deceleration amount required in order to avoid a lane departure is applied, it is predicted that it will repel each other with the driving force generated according to the required driving force τm. The braking / driving force repulsive force τc corresponding to the repulsive force is calculated. Specifically, when the departure determination flag FLD is “OFF”, the braking / driving force repulsive force τc = 0 is set. Further, when the departure determination flag FLD is “ON”, it is set according to the deviation between the estimated lateral displacement Xs and the departure determination threshold value Xc, and when Xs ≧ Xc, it is based on the following equation (9). If Xs ≦ −Xc, it is calculated based on the following equation (10).
τc = K11 × K12 × | Xs−Xc | (9)
τc = K11 × K12 × | Xs + Xc | (10)
Note that K11 in the equation is a proportional coefficient determined by vehicle specifications. K12 is a proportional coefficient that varies depending on the vehicle speed, and is set to decrease as the vehicle speed increases, for example.

  Next, the process proceeds to step S15, and the target driving force τs is calculated. The target driving force τs is calculated based on the required driving force τm calculated in step S11 and the braking / driving force repulsive force τc calculated in step S14. Specifically, when the braking / driving force repulsive force τc is within a range achievable by limiting the driver's required driving force τm within a range of zero or more and generating an engine braking force, the driver's request Calculated by subtracting the braking / driving force repulsive force τc from the driving force τm, and if it exceeds the achievable range, the target driving force τs is limited by the engine braking force, and the braking force is controlled for the shortage To achieve.

That is, when the departure determination flag FLD is “OFF”, it is not necessary to limit the driving force, so the required driving force τm corresponding to the accelerator opening Acc is set as the target driving force τs. On the other hand, when the departure determination flag FLD is “ON”, the cases are classified. When the braking / driving force repulsive force satisfies τc ≦ τm + τe, the target driving force τs is calculated by the following equation (11): When τc> τm + τe is satisfied, the calculation is performed by the following equation (12).
Note that τe is an absolute value of the engine braking force that can be expected at this time, and is calculated based on the operating state of the engine, the automatic transmission, the throttle opening, and the like at this time.
τs = τm−τc (11)
τs = −τe (12)

Next, the process proceeds to step S16, and the target braking force τb is calculated. Specifically, of the braking / driving force repulsive force τc calculated in step S14, a portion corresponding to the braking / driving force repulsive force that is insufficient even if the driving force is limited in step S16 is set as the target braking force τb. That is, when the departure determination flag FLD is “ON” and the braking / driving force repulsive force τc is τc ≦ τm + τe, the target braking force is set to τb = 0. Conversely, when τc> τm + τe, the target braking force τb is calculated from the following equation (13).
τb = τc− (τm + τe) (13)

Based on the target braking force τb calculated in this way and the master cylinder pressure Pm read in step S11, the target braking fluid pressure Psi for each wheel is calculated.
Also in this case, as in the first reference embodiment , when 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 S11, the departure determination flag When FLD is “OFF”, the target brake fluid pressures PsFL and PsFR for the front left and right wheels 5FL and 5FR to the wheel cylinders 6FL and 6FR are both the master cylinder pressure Pm, and the rear left and right wheels 5RL and 5RR are wheel cylinders. The target braking fluid pressures PsRL and PsRR for 6RL and 6RR are both the rear wheel master cylinder pressure PmR.

On the other hand, when the departure determination flag FLD is “ON”, the target braking fluid pressure Psi to each of the wheel cylinders 6FL to 6RR is given by the following equation (14).
PsFL = Pm + KbF × τb
PsFR = Pm + KbF × τb
PsRL = PmR + KbR × τb
PsRR = PmR + KbR × τb (14)
Here, the case where the sum of the brake fluid pressure converted from the target brake force τb and the master cylinder pressure Pm is described as the target brake fluid pressure Ps of each wheel is not limited to this. For example, The larger one of the target braking fluid pressure Ps and the master cylinder pressure Pm may be selected.

When the target braking force is calculated in this way, the process proceeds to step S17, and a driving force control signal is output toward the driving torque control unit 12 so as to generate the target driving force τs calculated in step S15.
Next, the process proceeds to step S18, and the target braking fluid pressure of each wheel calculated in step S16 is output to the braking fluid pressure control circuit 7. Further, when the deviation determination flag FLD is “ON”, processing such as operating the warning monitor 23 is performed. Then, the program returns to the main program.

Next, the operation of the embodiment of the present invention will be described.
In this embodiment of the present invention, when there is no lane departure tendency, the departure determination flag FLD is “OFF”, so the braking / driving force repulsive force τc is zero (step S14), and the target driving force is τs = τm. (Step S15), the target braking force is set to τb = 0 (Step S16). Accordingly, deceleration for avoiding lane departure is not performed, and the required driving force τm corresponding to the amount of operation of the accelerator pedal is generated, resulting in a traveling state that is in line with the driver's operation.

  From this state, when the lane departure tendency is set and the departure determination flag FLD is “ON”, the braking / driving force repulsive force τc is calculated based on the lane departure amount (Xs−Xc) at this time. When the braking / driving force repulsive force τc is equal to or less than the sum of the driver's required driving force τm and the engine braking force τe, the target braking force τs is set as τs = τm−τc. The power τb is set as zero, and a braking force and a driving force are generated accordingly.

  Accordingly, the accelerator pedal is operated, and the required driving force τm should be generated, but the braking / driving corresponding to the deceleration amount necessary to suppress the lane departure amount of the host vehicle at this time. Since the value obtained by subtracting the force repulsive force τc from the required driving force τm is set as the target driving force τs, the deceleration amount necessary for avoiding the lane departure acts on the vehicle as a result. A driving force obtained by subtracting the amount corresponding to the deceleration amount for avoiding lane departure from τm is generated, so that the braking force for avoiding lane departure does not interfere with the driving force requested by the driver, and avoids lane departure. Thus, it is possible to generate a driving force according to a driver request while securing a necessary deceleration amount.

  In this case, when the braking / driving force repulsive force τc is larger than the sum of the required driving force τm and the engine braking force τe, such as when the lane departure amount of the host vehicle is large and the driver's accelerator pedal operation amount is small. The engine braking force τe is set as the target driving force τs, and the value obtained by subtracting the sum of the required driving force τm and the engine braking force τe from the braking / driving force repulsive force τc is set as the target braking force τb. .

  That is, even if the required driving force τm is limited and the engine braking force τe is generated, if the braking force corresponding to the braking / driving force repulsive force τc cannot be generated, the driving force is equivalent to the engine brake τe. As a result, a deceleration amount corresponding to the braking / driving force repulsive force τc can be applied to the vehicle. Also in this case, since the required driving force τm is reduced and the shortage is compensated by generating the braking force, the interference between the driving force and the braking force is avoided, and lane departure is avoided. It is possible to generate the driving force as much as possible while ensuring the braking force.

Further, in this embodiment of the present invention, the driving force is reduced according to the amount corresponding to the braking / driving force repulsion force τc corresponding to the lane departure amount of the host vehicle, and the braking force is generated as necessary. Therefore, the driving force or the braking force can be changed smoothly in accordance with the change in the lane departure amount, and the driving force can be quickly recovered along with the recovery of the lane departure amount.

In the above- described embodiment of the present invention , the braking / driving force repulsive force τc is calculated, the required driving force τm is adjusted, and further, the amount of deceleration corresponding to the braking / driving force repulsive force τc is compensated by the braking force. However, it is also possible to reduce only the required driving force τm. In this case, when the required driving force τm is smaller than the braking / driving force repulsive force τc, the deceleration amount corresponding to the braking / driving force repulsive force τc cannot be secured, but the required driving force τm and the lane departure avoidance are avoided. Although it is possible to avoid the interference with the deceleration amount necessary for the vehicle, there are cases where it is not sufficient, but the control effect by the control for avoiding the lane departure can be obtained.

Here, in the above- described embodiment of the present invention, the process in step S13 in FIG. 5 corresponds to the departure detecting means, the processes in steps S14 to S18 in FIG. 5 correspond to the departure avoidance control means, and the drive torque control unit 12 And the engine 9 corresponds to the braking / driving force generating means, and the process of calculating the required driving force τm corresponding to the accelerator opening Acc from the accelerator opening sensor 18 corresponds to the braking / driving force required amount detecting means, as shown in FIG. The process in step S14 corresponds to the repulsive force detection means, the process in step S15 corresponds to the braking / driving force suppression means, the process in step S16 corresponds to the deceleration control amount calculation means, and the process in step S18 corresponds to the deceleration control means. Correspondingly, the processing of steps S17 and S18 corresponds to the braking / driving force control means.

In each of the above-described embodiments, the case where the lane deviates to the left side has been described.
Moreover, in each said embodiment, it applies when generating the driving force according to depression of an accelerator pedal, the accelerator opening degree sensor 18 is applied as a driving force request | requirement amount detection means, and according to accelerator opening Acc Although the case where the driving force is suppressed has been described, the present invention is not limited to this. For example, the vehicle speed control is performed so that the vehicle travels at a constant distance from the preceding vehicle or travels at a constant speed. The present invention can also be applied to the case where a driving force according to a driving torque command value from a known follow-up travel control device is generated. In this case, the driving torque command value is detected by a driving force request amount detection means. However, the driving force corresponding to this may be suppressed.

It is a schematic block diagram which shows an example of the vehicle carrying the lane departure prevention apparatus in this invention. It is a flowchart which shows an example of the process sequence of the arithmetic processing performed within the vehicle state control unit of FIG. 3 is a control map used in the arithmetic processing of FIG. 3 is a control map used in the arithmetic processing of FIG. It is a flowchart which shows an example of the process sequence of the arithmetic processing performed by embodiment of this invention .

Explanation of symbols

5FL to 5RR Wheel 6FL to 6RR Wheel cylinder 7 Braking fluid pressure control circuit 8 Vehicle state control unit 9 Engine 12 Drive torque control unit 13 Monocular 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 to 22RR Wheel speed sensor 23 Monitor

Claims (6)

Departure detection means for detecting whether the host vehicle is in a lane departure tendency;
  A departure avoidance control means for controlling the vehicle behavior of the host vehicle in a direction to avoid a departure from the traveling lane of the host vehicle when it is detected by the departure detection means that the vehicle is in a lane departure tendency;
  Braking / driving force request amount detecting means for detecting a braking / driving force request amount required by the operation of the driver;
  Braking / driving force generating means for generating braking / driving force according to the requested braking / driving force amount;
  A repulsive force corresponding to the braking / driving force acting in the direction of inhibiting the other between the braking / driving force generated by the departure avoidance control means and the braking / driving force according to the required amount of braking / driving force. Repulsive force detection means for detecting as,
  Braking / driving force suppressing means for suppressing the braking / driving force generated by the braking / driving force generating means by an amount corresponding to the repulsive force detected by the repulsive force detecting means when it is detected that the vehicle is in a lane departure tendency; Prepared,
  A lane departure prevention apparatus, wherein interference between the braking / driving force generated by the departure avoiding control by the departure avoiding control means and the braking / driving force generated by the braking / driving force generating means is prevented. The departure avoidance control means includes a deceleration control amount calculation means for calculating a deceleration control amount for avoiding departure,
  Deceleration control means for performing braking / driving force control so as to generate a deceleration corresponding to the deceleration control amount calculated by the deceleration control amount calculation means,
  The lane departure prevention according to claim 1, wherein the deceleration control amount calculation means calculates the deceleration control amount based on a deviation between a braking / driving force corresponding to the braking / driving force request amount and the repulsive force. apparatus. An engine brake force detecting means for detecting the engine brake force;
  The deceleration control amount calculating means detects the braking / driving force corresponding to the requested braking / driving force and the engine braking force detecting means when the repulsive force is greater than the braking / driving force corresponding to the requested braking / driving force. The lane departure prevention apparatus according to claim 2, wherein a value obtained by subtracting the sum of the engine braking force and the repulsive force from the repulsive force is calculated as the deceleration control amount. Departure detection means for detecting whether the host vehicle is in a lane departure tendency;
  Braking / driving force request amount detecting means for detecting a braking / driving force request amount required by the operation of the driver;
  Braking / driving force generating means for generating braking / driving force according to the requested braking / driving force amount;
  When it is detected by the departure detecting means that there is a tendency to deviate from the lane, the braking / driving required for generating the braking / driving force corresponding to the required amount of braking / driving force and the deceleration to avoid the tendency to deviate from the lane. A repulsive force detecting means for detecting a braking / driving force component acting in a direction that inhibits the other as a repulsive force,
  When it is detected that there is a tendency to deviate from the lane, a braking / driving force for subtracting the repulsive force from the braking / driving force generated by the braking / driving force generating means to generate a deceleration corresponding to the repulsive force is calculated. Braking / driving force calculating means for
  A lane departure prevention apparatus comprising: braking / driving force control means for controlling the braking / driving force so as to generate the braking / driving force calculated by the braking / driving force calculating means. 4. The braking / driving force suppression unit cancels the suppression of the braking / driving force when it is predicted that the braking / driving force suppression unit has recovered from the departure tendency based on the detection result of the departure detection unit. The lane departure prevention device according to any one of the above. 4. The braking / driving force suppressing means limits a variation amount of braking / driving force generated by the braking / driving force generating means in accordance with suppression or release of the braking / driving force. The lane departure prevention device according to any one of the above.

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