JP2010023606A - Lane deviation preventive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lane deviation preventive device capable of changing the control state at an adequate timing when an obstacle is present in front of one's own vehicle. <P>SOLUTION: The lane deviation preventive device for generating the steering torque to prevent any deviation of one's own vehicle OV from a traveling lane includes: a one's own vehicle advancing road estimating means 140 for estimating an advancing road of one's own vehicle; an obstacle recognizing means 130 for recognizing an obstacle F in front of one's own vehicle; a lap amount computing means 150 for computing the lapping degree in the transverse direction between one's own vehicle and the obstacle as the lapping amount; a deviation preventive control reducing means 160 for reducing the steering torque toward the center side of the traveling lane according to an approaching state of the obstacle to one's own vehicle; and a timing changing means for advancing the timing of reducing the steering torque by the deviation preventive control reducing means according to an increase in the lap amount. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lane departure prevention device that is provided in a vehicle such as an automobile and prevents a departure from the lane of the host vehicle, and in particular, changes the control state at an appropriate timing when an obstacle exists in front of the host vehicle. About things.

  The lane departure prevention device recognizes, for example, the width and shape of the lane in which the host vehicle travels by environment recognition means such as an image capturing device and detects the tendency of the host vehicle to deviate from the lane. Driving assistance such as issuing a warning or generating steering assistance force in the restoring direction is performed.

The lane departure prevention device is required not to prevent the avoidance operation by the driver when there is an obstacle ahead of the host vehicle. For this reason, a lane departure prevention device has been proposed that changes the state of control when an obstacle that needs to be avoided by changing the course is detected.
For example, in Patent Document 1, white lines and three-dimensional objects on the left and right sides of the host vehicle are detected from an image captured in front of the host vehicle, and the driver intentionally uses the distance between the left and right ends of the three-dimensional object and the corresponding white lines. There is described a lane departure prevention apparatus that determines that the vehicle has deviated from the lane and stops the departure prevention control.

Patent Document 2 describes that when a parked vehicle ahead of the host vehicle is detected, the actual lane that is a threshold value for departure avoidance control is changed to a virtual line shifted in the horizontal direction.
JP 2007-264717 A JP 2005-324882 A

  However, the timing at which the state of the lane departure prevention control should be changed differs depending on the degree of overlap of the obstacle with the host vehicle or the lane. For example, if the lane departure prevention control state is changed at the same timing regardless of the degree of overlap, if the degree of overlap with the host vehicle or lane width is large and the driver wants to start avoidance early, avoidance Interference is likely to occur. On the other hand, when the degree of overlap is small, the control expected by the driver cannot be performed because the control state changes despite sufficient time until avoidance starts.

  The subject of this invention is providing the lane departure prevention apparatus which changes the state of control at an appropriate timing, when an obstruction exists ahead of the own vehicle.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 estimates an estimated traveling path of the host vehicle in a lane departure prevention apparatus that performs a departure prevention control that generates a steering torque toward the center of the traveling lane so as to prevent the departure of the own vehicle from the traveling lane. The own vehicle traveling path estimating means, the obstacle recognizing means for recognizing an obstacle ahead of the own vehicle, and the overlapping degree in the lateral direction of the own vehicle and the obstacle on the estimated traveling path of the own vehicle are calculated as a lap amount. A lap amount calculating means, a departure prevention control reducing means for reducing the steering torque toward the traveling lane center side according to the approaching state of the obstacle to the host vehicle, and the departure prevention control reduction according to the increase of the lap amount A lane departure prevention apparatus characterized in that the means comprises a timing changing means for speeding up the timing for reducing the steering torque.
In the present specification, claims, and the like, the reduction in steering torque includes those that completely stop the generation of steering torque.

  The invention according to claim 2 further includes a collision prediction time calculation unit that calculates a collision prediction time for the obstacle of the host vehicle, wherein the timing changing unit sets a collision time threshold based on the lap amount, and the collision prediction is performed. 2. The lane departure prevention apparatus according to claim 1, wherein when the time becomes equal to or less than the collision time threshold value, the steering torque is reduced by the departure prevention control reduction unit.

According to a third aspect of the present invention, in the lane departure prevention apparatus for performing the departure prevention control for generating the steering torque toward the center of the traveling lane so as to prevent the departure of the own vehicle from the traveling lane, the lane width on the traveling path of the own vehicle is calculated. Lane width calculating means, obstacle recognizing means for recognizing an obstacle ahead of the own vehicle, occupancy calculating means for calculating the degree of occupancy of the obstacle with respect to the lane width as an occupancy, and the vehicle of the obstacle The departure prevention control reduction means for reducing the steering torque toward the center of the lane according to the approaching state to the vehicle, and the timing at which the departure prevention control reduction means reduces the steering torque according to the increase in the occupied amount is advanced. A lane departure prevention apparatus comprising timing change means.
The invention according to claim 4 includes a collision prediction time calculation unit that calculates a collision prediction time for the obstacle of the host vehicle, wherein the timing changing unit sets a collision time threshold based on the occupation amount, and the collision prediction is performed. 4. The lane departure prevention apparatus according to claim 3, wherein when the time becomes equal to or less than the collision time threshold, the strength toward the lane center by the departure prevention control lowering means is reduced.

According to a fifth aspect of the present invention, there is provided a lane departure prevention apparatus for performing departure prevention control for generating a steering torque toward a target travel position so as to prevent a departure from the travel lane of the host vehicle, and estimating a traveling path of the host vehicle. The own vehicle traveling path estimating means, the obstacle recognizing means for recognizing an obstacle ahead of the own vehicle, and the overlapping degree in the lateral direction of the own vehicle and the obstacle on the estimated traveling path of the own vehicle are calculated as a lap amount. A lap amount calculation means, a target travel position shift means for shifting the target travel position in a lateral direction according to the approaching state of the obstacle to the host vehicle, and a shift of the target travel position according to an increase in the lap amount It is a lane departure prevention apparatus characterized by including a timing changing means for speeding up the timing of the lane departure.
The invention according to claim 6 includes a collision prediction time calculation unit that calculates a collision prediction time for the obstacle of the host vehicle, wherein the timing changing unit sets a collision time threshold based on the lap amount, and the collision prediction is performed. 6. The lane departure prevention apparatus according to claim 5, wherein the target travel position is shifted when the time becomes equal to or less than the collision time threshold value.

The invention according to claim 7 is a lane departure prevention apparatus that performs departure prevention control for generating a steering torque toward a target travel position so as to prevent a departure from the travel lane of the host vehicle. A lane width calculating means for calculating an obstacle, an obstacle recognizing means for recognizing an obstacle ahead of the host vehicle, an occupancy amount calculating means for calculating an occupancy degree of the obstacle with respect to the lane width as an occupancy amount, A target travel position shifting means for shifting the target travel position in a lateral direction in accordance with an approaching situation to the host vehicle; and a timing changing means for speeding up the timing for shifting the target travel position in accordance with an increase in the occupied amount. A lane departure prevention apparatus characterized by the above.
The invention according to claim 8 is provided with a collision prediction time calculation means for calculating a collision prediction time for the obstacle of the host vehicle, wherein the timing changing means sets a collision time threshold based on the occupation amount, and the collision prediction 8. The lane departure prevention apparatus according to claim 7, wherein the target travel position is shifted when the time becomes equal to or less than the collision time threshold value.

The invention according to claim 9 is characterized in that, when the obstacle is a stopped vehicle, the lap amount calculating device calculates the lap amount by performing a predetermined increase correction on the lateral width of the stopped vehicle. The lane departure prevention device according to any one of claims 1, 2, 5, and 6.
The invention according to claim 10 is characterized in that, when the obstacle is a stopped vehicle, the occupation amount calculation device calculates the occupation amount by performing a predetermined increase correction on the lateral width of the stopped vehicle. A lane departure prevention apparatus according to any one of claims 3, 4, 7, and 8.

According to the present invention, the following effects can be obtained.
(1) The degree of overlap between the host vehicle and the obstacle in the lateral direction is calculated as a lap amount, and the timing for decreasing the steering torque toward the center of the traveling lane according to the increase in the lap amount is increased. The steering torque can be reduced at an appropriate timing according to the degree of overlap with the obstacle.
For example, when the lap amount is large and it is necessary to start avoidance at an early stage, the steering torque is reduced early, thereby preventing interference with the avoidance operation by the driver and reducing bothersomeness and uncomfortable feeling. .
On the other hand, when the lap amount is small and the avoidance start may be relatively late, delaying the timing for lowering the steering torque delays the start of avoidance so that the driver expects steering assistance. A reduction in steering torque can be prevented, and convenience can be improved.

(2) The occupancy of the obstacle with respect to the lane width ahead of the host vehicle is calculated as the occupancy, and the lane width is increased by increasing the timing at which the steering torque toward the center of the traveling lane is reduced according to the increase in the occupancy. The steering torque can be reduced at an appropriate timing according to the degree of overlap with the obstacle.
For example, when the occupancy is large and it is necessary to start avoidance at an early stage, by reducing the steering torque at an early stage, it is possible to prevent interference with the avoidance operation by the driver and reduce annoyance and discomfort. .
On the other hand, if the occupancy is small and the avoidance start may be relatively late, delaying the timing for lowering the steering torque delays the start of avoidance so that the driver expects steering assistance. A reduction in steering torque can be prevented, and convenience can be improved.

(3) The overlap between the host vehicle and the obstacle is calculated by calculating the degree of overlap in the lateral direction between the host vehicle and the obstacle as a lap amount, and by increasing the timing for shifting the target travel position according to the increase in the lap amount. The target travel position can be shifted at an appropriate timing according to the degree, and interference with the driver's avoidance operation can be reduced.

(4) The occupancy of the obstacle with respect to the lane width ahead of the host vehicle is calculated as the occupancy, and the lane width overlaps with the obstacle by increasing the timing for shifting the target travel position according to the increase in the occupancy. The target travel position can be shifted at an appropriate timing according to the degree, and interference with the driver's avoidance operation can be reduced.

(5) When the obstacle is a stopped vehicle, a predetermined increase correction is performed on the lateral width of the stopped vehicle to calculate a lap amount or an occupancy amount, so that even when the door of the stopped vehicle is opened, Safety can be improved with easy avoidance.

  It is an object of the present invention to provide a lane departure prevention device that changes the state of control at an appropriate timing when an obstacle is present in front of the host vehicle, the lap ratio between the obstacle and the host vehicle, or the lane width of the obstacle. The timing at which the steering torque is reduced according to the occupancy ratio for the vehicle and the timing for changing the target travel position according to the lap ratio between the obstacle and the vehicle or the occupancy ratio for the lane width of the obstacle are changed. Solved by.

Embodiment 1 of a lane departure prevention apparatus to which the present invention is applied will be described below.
The lane departure prevention apparatus according to the first embodiment is provided in, for example, a four-wheeled vehicle such as a passenger car that steers the two front wheels.
FIG. 1 is a diagram illustrating a system configuration of a vehicle including a lane departure prevention apparatus according to an embodiment. This lane departure prevention device applies steering torque (steering force) to the steering mechanism 10.
The steering mechanism 10 performs steering by rotating the housing H that supports the front wheel FW about a predetermined steering axis (king pin).

The steering mechanism 10 includes a steering wheel 11, a steering shaft 12, a steering gear box 13, a tie rod 14, and the like.
The steering wheel 11 is an annular operation member through which a driver inputs a steering operation.
The steering shaft 12 is a rotating shaft that transmits the rotation of the steering wheel 11 to the steering gear box 13.
The steering gear box 13 includes a rack and pinion mechanism that converts the rotational movement of the steering shaft 12 into a straight movement in the vehicle width direction.
The tie rod 14 is a shaft-like member having one end connected to the rack of the steering gear box 13 and the other end connected to the knuckle arm of the housing H. The tie rod 14 steers by rotating the housing H by pushing and pulling the knuckle arm of the housing H.

  The vehicle also includes an electric power steering (EPS) control unit 20, a steering control unit 30, an engine control unit 40, a transmission control unit 50, a vehicle integration unit 60, and the like.

The EPS control unit 20 comprehensively controls the electric power steering apparatus that generates a steering assist force in accordance with the driver's steering operation. The EPS control unit 20 is connected to an electric actuator 21, a steering angle sensor 22, a torque sensor 23, and the like.
The electric actuator 21 is, for example, an electric motor that is provided in the middle of the steering shaft 12 and applies a steering torque (steering force) to the steering mechanism 10 via a speed reduction mechanism.
The steering angle sensor 22 includes an encoder that detects the angular position of the steering shaft 12 (substantially equal to the angular position of the staying wheel 11).
The torque sensor 23 is inserted into the steering shaft 12 between the electric actuator 21 and the steering wheel 11 and detects torque acting on the steering shaft 12. Normally, the torque detected by the torque sensor 23 is substantially equal to the steering torque input to the steering wheel 11 by the driver.

The steering control unit 30 performs vehicle steering control and ABS control for individually controlling the braking force of each wheel brake. In vehicle stability control, when understeer or oversteer occurs, the braking force on the turning inner wheel side and the outer wheel side is made different to generate a yaw moment in the restoring direction. ABS control (anti-lock brake control) is for reducing and recovering the braking force of a wheel when the tendency of the wheel to lock is detected.
The steering control unit 30 is connected to a hydraulic control unit (HCU) 31, a vehicle speed sensor 32, a yaw rate sensor 33, a lateral acceleration (lateral G) sensor 34, and the like.

The HCU 31 is a device that individually controls the brake fluid hydraulic pressure applied to the hydraulic service brake of each wheel. The HCU 31 includes a motor pump that pressurizes the brake fluid, a solenoid valve that adjusts the pressure applied to the caliper cylinder of each wheel, and the like.
The vehicle speed sensor 32 is provided in a housing that holds the hub bearing of each wheel, and outputs a vehicle speed pulse signal corresponding to the wheel speed. The vehicle speed pulse signal is subjected to predetermined processing, whereby the traveling speed of the vehicle can be obtained.
The yaw rate sensor 33 and the lateral G sensor 34 include a MEMS sensor that detects a rotational speed around the vertical axis of the vehicle body and a lateral acceleration, respectively.

The engine control unit 40 controls the engine, which is a driving power source for the vehicle, and its auxiliary equipment.
The transmission control unit 50 controls the automatic transmission that shifts the output of the engine and transmits it to the front and rear differentials.
The vehicle integration unit 60 controls the electrical components of the vehicle other than those related to each unit.

Further, the lane departure prevention apparatus of the first embodiment includes a lane departure prevention control unit 100 described below.
The lane departure prevention control unit 100 is connected to the above-described EPS control unit 20, the operation control unit 30, the engine control unit 40, the transmission control unit 50, and the vehicle integration unit 60 via an in-vehicle LAN such as a CAN communication system. Various information and signals can be acquired.

  The lane departure prevention control unit 100 includes an environment recognition unit 110, a lane recognition unit 120, an obstacle recognition unit 130, an own vehicle traveling path estimation unit 140, a lap rate calculation unit 150, a steering control unit 160, and the like. Each of these means may be configured as independent hardware, or a part or all of them may be configured as common hardware.

The environment recognition unit 110 recognizes the shape of the traveling lane of the host vehicle, the shape, size, position (direction and distance) of the obstacle including the preceding vehicle, based on the image information obtained by capturing the front of the host vehicle. is there.
The environment recognition unit 110 is connected to a stereo camera 111, an image processing unit 112, and the like.
The stereo camera 111 includes, for example, a pair of main cameras and sub-cameras provided near the room mirror base at the upper end of the front window of the vehicle. Each of the main camera and the sub camera has a CCD camera. The main camera and the sub camera are installed apart from each other in the vehicle width direction. The main camera and the sub camera capture a reference image and a comparative image, respectively, and output image data related to these images to the image processing unit 112.
The image processing unit 112 performs A / D conversion on the image data of the reference image and the comparison image output from the stereo camera 111, performs predetermined image processing, and outputs the result to the environment recognition unit 110. This image processing includes, for example, correction of an attachment position error of each camera, noise removal, gradation optimization, and the like. The digitized image has, for example, a plurality of pixels arranged in a matrix in the vertical direction and the horizontal direction. Each of these pixels has a luminance value corresponding to the brightness of the subject.

  The environment recognition unit 110 detects the parallax of a pixel group that is a block composed of an arbitrary pixel or a plurality of pixels on the reference image based on the data of the reference image and the comparison image. This parallax is the amount of deviation between the position on the reference image and the position on the comparison image of a certain pixel or pixel group. Using this parallax, the distance from the vehicle to the subject corresponding to the pixel can be calculated based on the principle of triangulation.

The lane recognition unit 120 uses the environment recognition unit 110 to recognize the shape of the white line arranged at both ends of the lane ahead of the host vehicle. In this specification, claims, etc., a white line means a continuous line or a broken line drawn at the end in the width direction of the lane, and the actual color is other than white (for example, amber) Includes lines.
FIG. 2 is a diagram illustrating an example of a planar arrangement of the own vehicle, the lane (white line), the obstacle, and the own vehicle traveling path trajectory.
In the example shown in FIG. 2, the traveling lane of the host vehicle OV is a left curve, and the host vehicle traveling path locus Pov is set at a substantially central portion of the lane width. In addition, the obstacle F is present on the left side of the central portion in the traveling lane (interval between the left and right white lines WL).

The lane recognition unit 120 detects a pixel group of the white line WL portion based on the luminance data of the pixel from the reference image data generated by the environment recognition unit 110. The orientation of the pixel group of the white line WL portion with respect to the host vehicle is detected based on the pixel position on the image data. Specifically, an area corresponding to a pixel position in the vertical direction on the road surface is scanned in the horizontal direction, and a portion where the luminance value changes suddenly is recognized as a lane outline. Then, the position of the white line is detected by calculating the distance of the pixel group in the white line portion.
The lane recognition means 120 can continuously detect white line positions and set a plurality of lane candidate points in the traveling direction of the vehicle, ignore lane candidate points that cannot be matched, and set lane candidate points. The area that does not exist is subjected to a predetermined complement process to recognize the lane shape ahead of the host vehicle.

The obstacle recognizing means 130 recognizes an obstacle F that is at least partially overhanging the traveling lane of the host vehicle using the environment recognizing means.
The obstacle recognizing unit 130 recognizes the distance L and the width Wf of the obstacle F in real time and can determine whether the obstacle F is a vehicle or a vehicle other than the vehicle by pattern recognition based on the image. In the first embodiment, the distance of the obstacle is detected by the stereo camera 111. However, the distance is not limited to this, and other known ranging means such as a radar such as a millimeter wave radar may be used.
The obstacle recognition means 130 has a known surface recognition function for discriminating the rear surface (surface on the own vehicle OV side) and side surface (surface substantially orthogonal to the rear surface and substantially along the lane direction) of the obstacle F. As the width Wf of the obstacle F, for example, the width of the rear surface (corresponding to the vehicle width when the obstacle F is a vehicle) can be used.

Further, the obstacle recognition means 130 has a function of calculating a relative speed Vc between the host vehicle OV and the obstacle F in the traveling direction of the host vehicle (Z-axis direction) based on the history of the distance L.
Here, the obstacle recognizing means 130 estimates that the obstacle F is a stopped vehicle when the obstacle F is a vehicle and the relative speed Vc is substantially the same as the vehicle speed V of the host vehicle. A predetermined increase correction is performed on the lateral width Wf of F. This increase correction is performed in consideration of the possibility that the door of the stopped vehicle is opened. For example, the increase correction is performed by adding a predetermined width or multiplying by a predetermined coefficient.

また、自車進行路推定手段１４０は、上述した推定横位置の演算を略リアルタイムに連続して行うことによって、図２に示すような自車両ＯＶの進行方向に連続した自車進行路軌跡Ｐｏｖを設定することができる。 The own vehicle traveling path estimation means 140 is based on the information from the environment recognition means 110, the running state of the vehicle detected by the steering angle sensor 22, the vehicle speed sensor 32, the yaw rate sensor 33, and the known vehicle specifications. The vehicle traveling path is estimated.
The own vehicle traveling path is estimated by, for example, calculating the lateral position Xe of the own vehicle OV at a predetermined distance L in front of the vehicle.
This will be described below using a coordinate system having an X-axis extending in the vehicle width direction and a Z-axis extending forward of the vehicle body with the center of gravity of the host vehicle OV as the origin.
The estimated lateral position Xe of the host vehicle center of gravity at the distance L is obtained by the following expression 1 using the handle angle α.

Further, the host vehicle traveling path estimation unit 140 continuously calculates the estimated lateral position described above in substantially real time, so that the host vehicle traveling path locus Pov continuous in the traveling direction of the host vehicle OV as shown in FIG. Can be set.

In addition, the vehicle traveling path estimation unit 140 may estimate the lateral position using the yaw rate detected by the yaw rate sensor 33 as shown in the following equation 2, instead of estimating the lateral position using the steering wheel angle. it can.

Xe = L ² γ / 2V (Formula 2)
L: Obstacle distance [m]
γ: vehicle yaw rate [rad / sec]

The lap rate calculating means 150 calculates a lap amount, which is a degree of overlap in the lateral direction of the obstacle F in front of the host vehicle OV with respect to the host vehicle OV, as a lap rate.
The wrap rate _{N_lap} [%] is obtained by the following Equation 3.

The steering control means 160 uses the lane recognition means 120, the obstacle recognition means 130, the own vehicle traveling path estimation means 140, the lap ratio calculation means 150, etc., and whether or not the steering torque (support torque) needs to be applied to the steering mechanism 10. And setting a target steering torque when the steering torque is applied. The steering control means 160 also functions as a departure prevention control reducing means according to the present invention that stops applying the steering torque at a predetermined avoidance timing when an obstacle is present in front of the host vehicle.
The steering control means 160 performs lane departure prevention control so as to prevent the departure of the host vehicle from the traveling lane recognized by the lane recognition means 120. For example, when the own vehicle lateral position Xe estimated by the own vehicle traveling path estimating means 140 deviates from the lane, the steering control means 160 determines that there is a tendency to deviate, and the pulsating steering torque toward the lane center side. Is generated. Further, instead of applying such a pulsed steering torque, the target travel position Xc is set at the center of the travel lane so as to reduce the lateral deviation Δe between the estimated vehicle lateral position Xe and the target travel position Xc. Steering torque may be applied to. In this case, specifically, the target steering torque may be calculated by multiplying the cube of the lateral position deviation Δe by a predetermined gain and applying a predetermined correction thereto.

Further, the steering control means 160 has a function of stopping the above-described lane departure prevention control at a timing according to the lap rate _{N_lap} calculated by the lap rate calculation means 150 when there is an obstacle ahead of the _host vehicle.
Therefore, the steering control unit 160 includes a collision prediction time calculation unit 161 and an avoidance timing setting unit 162.
The collision prediction time calculation unit 161 calculates the time when the position of the host vehicle OV coincides with the end of the obstacle F on the vehicle side in the depth direction (Z-axis direction in FIG. 2) as the collision prediction time TTC. is there.

The collision prediction time TTC is obtained by the following equation 4.

TTC = L / Vr (Formula 4)
TTC: Time To Collision [sec]
L: Distance from the vehicle to the obstacle in the Z-axis direction [m]
Vr: Relative speed between the host vehicle and the obstacle in the Z-axis direction [m / sec]

The avoidance timing setting unit 162 sets an avoidance timing Tc, which is a timing (collision time threshold) that allows intentional departure by the driver's steering, based on the above-described collision prediction time TTC and lap rate _{N_lap} . At this time, the avoidance timing setting unit 162 functions as a timing changing unit according to the present invention. This function will be described in detail below.

Next, the control at the time of obstacle avoidance in the lane departure prevention apparatus of Example 1 mentioned above is demonstrated.
FIG. 3 is a flowchart showing control at the time of obstacle avoidance. Hereinafter, the steps will be described step by step.
<Step S01: Intervention of other control, emergency avoidance state presence / absence determination>
When the steering control unit 30 is performing vehicle stability control (yaw control control) or ABS control, the steering control means 160 has an understeer or oversteer tendency in the vehicle, or the ABS operates. It is determined that the sudden braking is being performed, and the process proceeds to step S02. Otherwise, the process proceeds to step S03.
<Step S02: Steering control stop>
The steering control means 160 stops all steering control (granting of steering torque) including lane departure prevention control, and ends (returns) the processing.

<Step S03: Environmental recognition>
The environment recognizing means 110 and the lane recognizing means 120 cooperate to recognize the shape of the traveling lane ahead of the host vehicle and also recognize the lateral position within the white line of the host vehicle OV.
The obstacle recognizing means 130 detects the obstacle width Wf, the lateral position Xf, the own vehicle depth direction position (distance) L, and the relative speed Vr between the own vehicle and the obstacle.
Thereafter, the process proceeds to step S04.
<Step S04: Trajectory estimation of own vehicle traveling path>
The own vehicle traveling path estimation means 140 sets the aforementioned own vehicle traveling path trajectory Pov. Then, the lateral position Xe of the host vehicle at the obstacle position L is estimated using the host vehicle traveling path locus Pov.
Thereafter, the process proceeds to step S05.

<Step S05: Calculation of Avoidance Timing Tc>
The predicted collision time calculation means 161 of the steering control means 160 uses the lap ratio _{N_lap} between the _host vehicle OV and the obstacle F calculated by the lap ratio calculation means 150 and the relative speed Vc detected by the obstacle recognition means 130. Thus, the collision prediction time TTC is calculated.
Then, the steering control means 160 sets the avoidance timing Tc using the collision prediction time TTC.
FIG. 4 is a graph showing the correlation between the lap rate _{N_lap} and the avoidance timing Tc in the first embodiment.
The avoidance timing Tc is obtained by the following equation 5.

Tc = a · _{N_lap} + TTC (Formula 5)
a: Predetermined constant

That is, the avoidance timing Tc is obtained by performing an increase correction according to the increase in the lap rate with reference to the collision prediction time TTC, and is set relatively short when the lap rate is small, and when the lap rate is large. Is set relatively long.

<Step S06: Determination of Winker Operation>
The steering control means 160 detects whether or not a turn signal (turn signal lamp) switch is operated via the integrated control unit 60. If there is a turn signal operation, the process proceeds to step S07. If there is no turn signal operation, step S07 is skipped and the process proceeds to step S08.
<Step S07: Update avoidance timing Tc to turn signal operation timing>
The steering control means 160 estimates that the driver intentionally deviates from the lane and updates the avoidance timing Tc to the blinker operation timing in order to turn off the lane departure prevention control as necessary, and proceeds to step S08.

<Step S08: Obstacle Crossing Determination>
The steering control means 160 performs obstacle straddling determination for determining whether or not the obstacle F straddles the white line WL at the lane edge.
FIG. 5 is a diagram illustrating an example of a planar arrangement of the host vehicle, the white line, and the obstacle when the obstacle straddles the white line.
The obstacle straddling determination is determined as a straddling state when the straddling determination value Rm becomes a negative value using the following Expression 6.

Rm = sgn (| x _l | −Wf / 2) (Expression 6)
Rm: Crossing judgment value _xl : Lane position [m] (+ is the left side and-is the right side in the coordinate system of the embodiment)

If the crossing determination is established, the obstacle is recognized as an obstacle that needs to be avoided, and the process proceeds to step S10. If not, the process proceeds to step S09.

<Step S09: Relative speed determination>
If the relative speed Vc between the host vehicle OV and the obstacle F is greater than or equal to a predetermined threshold value Vc_th, the steering control means 160 proceeds to step S10 assuming that there is a significant approach of the obstacle F to the host vehicle OV. In the case of, the process ends (returns).

<Step S10: Obstacle Direction Determination>
The steering control means 160 uses the obstacle recognition means 130 to determine whether the obstacle F straddles the left or right white line WL in the traveling lane of the host vehicle.
If it is on the left side, the process proceeds to step S11. If it is on the right side, the process proceeds to step S13.

<Step S11: Comparison Judgment between Collision Prediction Time and Avoidance Timing>
The steering control means 160 compares the current collision prediction time TTC calculated in real time with the avoidance timing Tc calculated in step S05, and if the collision prediction time TTC is equal to or less than the avoidance timing Tc, the process proceeds to step S12. In other cases, step S12 is skipped and the process ends (returns).
<Step S12: Stop lane departure prevention control to the right>
The steering control means 160 stops the steering torque application control to the left side with respect to the tendency of the own vehicle to deviate to the right side of the traveling vehicle, and ends (returns) the process.

<Step S13: Comparison Judgment between Collision Prediction Time and Avoidance Timing>
The steering control means 160 compares the current collision prediction time TTC calculated in real time with the avoidance timing Tc calculated in step S05. If the collision prediction time TTC is equal to or less than the avoidance timing Tc, the steering control unit 160 proceeds to step S14. In other cases, step S14 is skipped and the process ends (returns).
<Step S14: Stop lane departure prevention control to the left>
The steering control means 160 stops the control of applying the steering torque to the right side with respect to the tendency of the own vehicle to deviate to the left side of the traveling vehicle, and ends (returns) the process.

According to the first embodiment described above, the timing for stopping the _application of the steering torque to the center of the traveling lane is increased according to the increase in the lap ratio _{N_lap} indicating the degree of overlap between the _host vehicle OV and the obstacle F in the lateral direction. By doing so, the application of the steering torque can be stopped at an appropriate timing according to the degree of overlap between the host vehicle and the obstacle.
Further, when the obstacle F is a stopped vehicle, a predetermined increase correction is performed on the lateral width of the stopped vehicle to calculate a lap rate _{N_lap} , so that even when the door of the stopped vehicle is opened, Safety can be improved with easy avoidance.

Next, a second embodiment of the lane departure prevention apparatus to which the present invention is applied will be described.
In each of the embodiments described below, portions that are substantially the same as those of the previous embodiment are denoted by the same reference numerals, description thereof is omitted, and differences are mainly described.
The lane departure prevention apparatus according to the second embodiment sets the avoidance timing Tc based on the lane width occupation ratio _{N_lap_lane} described below instead of the lap ratio _{N_lap} in the first embodiment.

The lane departure prevention control unit 100 according to the second embodiment includes occupancy ratio calculation means (not shown) instead of the lap ratio calculation means 150 according to the first embodiment.
The occupancy rate calculation means is an index indicating the degree to which the obstacle F occupies within the lane width of the host vehicle travel lane. The occupation ratio is obtained by dividing the width (Xl−Xf + Wf / 2) of the portion where the obstacle F projects into the lane by the lane width. Here, when the obstacle F is a stopped vehicle, the occupation ratio is calculated after performing a predetermined increase correction on the width Wf of the obstacle, as in the case of the lap ratio described above.
Further, the avoidance timing setting unit 162 calculates the avoidance timing Tc using the occupation rate _{N_lap_lane} instead of the lap rate _{N_lap of the} first embodiment.
In this case, the avoidance timing Tc is obtained by the following expression 7.

Tc = b · _{N_lap_lane} + TTC (Expression 7)
b: Predetermined constant

Also, avoidance timing Tc may be set as, together taking into account the overlap ratio _{N _Lap} and occupancy _{N _Lap_lane} of the formula 8.

Tc = a * _{N_lap} + b * _{N_lap_lane} + TTC (Formula 8)

According to the second embodiment described above, the timing for stopping the _application of the steering torque to the center of the traveling lane is increased in accordance with the increase in the occupation amount _{N_lap_lane} indicating the degree of occupation of the obstacle F with respect to the lane width ahead of the _{host vehicle.} By doing so, the application of the steering torque can be stopped at an appropriate timing according to the overlapping degree of the lane width and the obstacle.

Next, a third embodiment of the lane departure prevention apparatus to which the present invention is applied will be described.
In the lane departure prevention apparatus of the third embodiment, the target travel position of the vehicle is changed instead of stopping the application of the steering torque when an obstacle is detected in the lane departure prevention apparatus of the first embodiment. It is.
The lane departure prevention control unit 100 of the lane departure prevention apparatus of the third embodiment further includes target travel position setting means (not shown). The target travel position setting means sets the target travel position Xc at the center of the lane width of the host vehicle travel lane recognized by the lane recognition means 120.
Then, the steering control means 160 feeds back the deviation between the estimated lateral position Xe of the own vehicle center of gravity estimated by the own vehicle traveling path estimation means 140 and the target travel position Xc, and sends the steering torque according to this deviation to the steering mechanism 10. Control to give.

  In the third embodiment, when the collision prediction time TTC becomes equal to or less than the avoidance timing Tc in steps S11 and S13 of the flowchart shown in FIG. 3, instead of stopping the lane departure prevention control in steps S12 and S14, target travel position setting means Shifts the target travel position laterally and moves away from the obstacle.

Above according to the third embodiment described, by depending on the increase of the overlapping ratio N _{_Lap} showing the overlapping degree in the transverse direction of the vehicle OV and the obstacle F, faster the timing of shifting the target traveling position, the own The target travel position can be shifted at an appropriate timing according to the degree of overlap between the vehicle OV and the obstacle F, and interference with the driver's avoidance operation can be reduced.

Next, a fourth embodiment of the lane departure prevention apparatus to which the present invention is applied will be described.
The lane departure prevention apparatus according to the fourth embodiment calculates the avoidance timing Tc using the occupation ratio _{N_lap_lane} in the same manner as the second embodiment. Then, when the predicted collision time TTC becomes equal to or less than the avoidance timing Tc, the target travel position is changed in the same manner as in the third embodiment.
According to the fourth embodiment described above, the lane width and the lane width can be increased by increasing the timing of shifting the target travel position according to the increase in the occupation ratio _{N_lap_lane} indicating the degree of occupancy of the obstacle F with respect to the lane width ahead of the _host vehicle. The target travel position can be shifted at an appropriate timing according to the degree of overlap with the obstacle, and interference with the driver's avoidance operation can be reduced.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) In the first and second embodiments, the application of the steering torque is stopped when the predicted collision time is equal to or less than the avoidance timing. However, the present invention is not limited to this, and is more than in the normal lane departure prevention control. It is good also as a structure which provides the reduced steering torque.
(2) In each embodiment, the lane recognition means detects the lane shape using a stereo camera. However, the present invention is not limited to this, for example, map data prepared for a navigation device or the like and the own vehicle position. The lane shape may be detected based on the positioning information.
(3) The configuration of the actuator that applies the steering torque to the steering mechanism is not limited to the column assist type as in the embodiment. For example, the pinion assist type that drives the pinion shaft connected to the steering shaft, the steering shaft A double pinion type that drives a pinion that is independent of the connected pinion, a rack direct-acting type that drives the steering rack itself in a straight direction, or the like may be used.
(4) In the first and third embodiments, the wrap rate that is the ratio of the width is used as the lap amount that is the degree of overlap between the host vehicle and the obstacle, but the parameters that can be applied as the lap amount are not limited to this. For example, the dimension (width) of the overlapping portion can be used as the wrap amount. Similarly, the occupation amount is not limited to the occupation ratio as in the second and fourth embodiments.

It is a figure which shows the system configuration | structure of the vehicle containing Example 1 of the lane departure prevention apparatus to which this invention is applied. It is a figure which shows an example of the planar arrangement | positioning of the own vehicle in the lane departure prevention apparatus of FIG. 1, a lane (white line), an obstruction, and the own vehicle advancing path locus. It is a flowchart which shows the control at the time of the obstacle avoidance in the lane departure prevention apparatus of FIG. It is a graph which shows the correlation with the lap | wrap rate and avoidance timing in the lane departure prevention apparatus of FIG. It is a figure which shows an example of the planar arrangement | positioning of the own vehicle in case an obstruction straddles a white line, a white line, and an obstruction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Steering mechanism 11 Steering wheel 12 Steering shaft 13 Steering gear box 14 Tie rod FW Front wheel H Housing 20 Electric power steering (EPS) control unit 21 Electric actuator 22 Steering angle sensor 23 Torque sensor 30 Steering control unit 31 Hydraulic control unit (HCU) )
32 vehicle speed sensor 33 yaw rate sensor 34 lateral acceleration (lateral G) sensor 40 engine control unit 50 transmission control unit 60 vehicle integrated unit 100 lane departure prevention control unit 110 environment recognition means 120 lane recognition means 130 obstacle recognition means 140 own vehicle traveling path Estimating means 150 Lap rate calculating means 160 Steering control means 161 Collision prediction time calculating means 162 Avoidance timing setting means OV Own vehicle WL White line F Obstacle

Claims (10)

In the lane departure prevention device for performing the departure prevention control for generating the steering torque toward the center of the traveling lane so as to prevent the departure of the own vehicle from the traveling lane,
Own vehicle traveling path estimation means for estimating the estimated traveling path of the host vehicle;
Obstacle recognition means for recognizing an obstacle ahead of the host vehicle;
A lap amount calculating means for calculating a degree of overlap in the lateral direction between the host vehicle and the obstacle on the estimated traveling path of the host vehicle as a lap amount;
Deviation prevention control reducing means for reducing the steering torque toward the traveling lane center side according to the approaching state of the obstacle to the host vehicle,
A lane departure prevention apparatus, comprising: timing changing means for speeding up the timing at which the departure prevention control reduction means reduces the steering torque in accordance with an increase in the lap amount. A collision prediction time calculating means for calculating a collision prediction time for the obstacle of the own vehicle;
The timing changing unit sets a collision time threshold based on the lap amount, and reduces the steering torque to the departure prevention control reducing unit when the predicted collision time becomes equal to or less than the collision time threshold. The lane departure prevention apparatus according to claim 1. In the lane departure prevention device for performing the departure prevention control for generating the steering torque toward the center of the traveling lane so as to prevent the departure of the own vehicle from the traveling lane,
Lane width calculating means for calculating the lane width on the own vehicle traveling path;
Obstacle recognition means for recognizing an obstacle ahead of the host vehicle;
Occupancy amount calculating means for calculating the occupancy degree of the obstacle with respect to the lane width as an occupancy amount;
Deviation prevention control reducing means for reducing the steering torque toward the traveling lane center side according to the approaching state of the obstacle to the host vehicle,
A lane departure prevention apparatus, comprising: a timing changing unit that accelerates the timing at which the departure prevention control reduction unit reduces the steering torque in accordance with an increase in the occupied amount. A collision prediction time calculating means for calculating a collision prediction time for the obstacle of the own vehicle;
The timing changing unit sets a collision time threshold value based on the occupation amount, and reduces the steering torque to the departure prevention control reducing unit when the predicted collision time becomes equal to or less than the collision time threshold value. The lane departure prevention apparatus according to claim 3. In a lane departure prevention device that performs departure prevention control that generates a steering torque toward a target traveling position so as to prevent departure from the traveling lane of the host vehicle,
Own vehicle traveling path estimation means for estimating the traveling path of the host vehicle;
Obstacle recognition means for recognizing an obstacle ahead of the host vehicle;
A lap amount calculating means for calculating a degree of overlap in the lateral direction between the host vehicle and the obstacle on the estimated traveling path of the host vehicle as a lap amount;
A target travel position shift means for shifting the target travel position in a lateral direction in accordance with an approach situation of the obstacle to the host vehicle;
A lane departure prevention apparatus, comprising: timing changing means for speeding up the timing of shifting the target travel position in accordance with an increase in the lap amount. A collision prediction time calculating means for calculating a collision prediction time for the obstacle of the own vehicle;
The timing changing means sets a collision time threshold value based on the lap amount, and shifts the target travel position when the predicted collision time becomes equal to or less than the collision time threshold value. The lane departure prevention apparatus described. In a lane departure prevention device that performs departure prevention control that generates a steering torque toward a target traveling position so as to prevent departure from the traveling lane of the host vehicle,
Lane width calculating means for calculating the lane width on the traveling path of the host vehicle;
Obstacle recognition means for recognizing an obstacle ahead of the host vehicle;
Occupancy amount calculating means for calculating the occupancy degree of the obstacle with respect to the lane width as an occupancy amount;
A target travel position shift means for shifting the target travel position in a lateral direction in accordance with an approach situation of the obstacle to the host vehicle;
A lane departure prevention apparatus, comprising: timing changing means for accelerating the timing for shifting the target travel position in accordance with the increase in the occupation amount. A collision prediction time calculating means for calculating a collision prediction time for the obstacle of the own vehicle;
The timing change means sets a collision time threshold value based on the occupation amount, and shifts the target travel position when the predicted collision time becomes equal to or less than the collision time threshold value. The lane departure prevention apparatus described. The lap amount calculation device, when the obstacle is a stopped vehicle, calculates the lap amount by performing a predetermined increase correction on the lateral width of the stopped vehicle. The lane departure prevention device according to any one of claims 5 and 6. The occupancy amount calculation device calculates the occupancy amount by performing a predetermined increase correction on a lateral width of the stopped vehicle when the obstacle is a stopped vehicle. The lane departure prevention device according to any one of claims 7 and 8.

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