JP5254688B2 - Lane departure prevention device - Google Patents

Description

  The present invention relates to a lane departure prevention apparatus that detects a lateral positional relationship between a host vehicle and a lane in a vehicle such as an automobile and generates a steering force in a direction that prevents the lane departure.

The lane departure prevention device recognizes the traveling lane of the host vehicle by an environment recognition means such as a stereo camera, and issues a warning when the tendency of the departure from the traveling lane of the host vehicle is determined. To steer.
For example, Patent Document 1 discloses a lane departure that activates an alarm unit having a vibration actuator incorporated in a steering wheel or a seat when a wheel enters an alarm region based on a separation line at the end of a traveling lane of the host vehicle. An alarm device is described.
Further, Patent Document 2 describes a lane departure prevention device that generates a yaw moment in a departure avoidance direction at a control start timing according to a road surface cant when the host vehicle tends to depart from a traveling lane.
JP 2007-249498 A JP 2005-145336 A

However, the conventional lane departure prevention device generates a steering force or outputs an alarm only after the departure tendency of the host vehicle occurs, and it is not considered to prevent the departure beforehand.
On the other hand, a lane tracking support device that sets a target travel position in a lane and drives the vehicle along the target travel position has been proposed, but when such control is performed, the driver intentionally When trying to travel at a position that deviates from the target travel position, interference with the driver's steering operation occurs, giving the driver a sense of discomfort.
The subject of this invention is providing the lane departure prevention apparatus which prevents a lane departure beforehand while reducing interference with a driver | operator's operation.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, in a lane departure prevention apparatus that applies a steering force to a steering mechanism so as to prevent a departure from the traveling lane of the host vehicle, environmental information in front of the host vehicle is acquired to set the traveling lane of the host vehicle. Lane setting means, a target travel position setting means for setting a target travel position of the host vehicle in the travel lane, and a lateral position relationship between the target travel position and the host vehicle from the travel lane of the host vehicle. Deviation determining means for determining a deviation tendency, and when it is determined that there is no deviation tendency, the steering force is applied in a direction to reduce the lateral displacement in accordance with an increase in lateral displacement of the host vehicle from the target travel position. Steering control means, and a second control mode for applying the pulsed steering force when it is determined that there is a tendency to deviate, and an obstacle ahead of the host vehicle is provided . Obstacle detection hand to detect And an approach degree calculating means for calculating an approach degree of the obstacle to the own vehicle based on a lateral position of the obstacle with respect to the own vehicle, wherein the steering control means has the approach degree higher than a predetermined value. Sometimes, the application of the steering force in the direction of approaching the obstacle according to the first control mode is stopped, and the approach degree calculation means is configured such that the obstacle is present when the obstacle exists outside the traveling lane of the own vehicle. A lateral distance between a driving lane edge of the vehicle closer to the obstacle and the obstacle is calculated as a risk, and the steering control means is configured to calculate the obstacle according to the first control mode when the lateral distance is a predetermined value or less. A lane departure prevention apparatus characterized in that only the application of a steering force in a direction approaching the vehicle is stopped .
According to a second aspect of the present invention, in a lane departure prevention apparatus that applies a steering force to a steering mechanism so as to prevent a departure from the traveling lane of the host vehicle, environmental information in front of the host vehicle is acquired to set the traveling lane of the host vehicle. Lane setting means, a target travel position setting means for setting a target travel position of the host vehicle in the travel lane, and a lateral position relationship between the target travel position and the host vehicle from the travel lane of the host vehicle. Deviation determining means for determining a deviation tendency, and when it is determined that there is no deviation tendency, the steering force is applied in a direction to reduce the lateral displacement in accordance with an increase in lateral displacement of the host vehicle from the target travel position. Steering control means, and a second control mode for applying the pulsed steering force when it is determined that there is a tendency to deviate, and an obstacle ahead of the host vehicle is provided. Obstacle detection hand to detect And an approach degree calculating means for calculating an approach degree of the obstacle to the own vehicle based on a lateral position of the obstacle with respect to the own vehicle, wherein the steering control means has the approach degree higher than a predetermined value. Sometimes, the application of the steering force in the direction of approaching the obstacle according to the first control mode is stopped, and the approach degree calculation means is configured such that the obstacle is present when the obstacle exists in the traveling lane of the host vehicle. The lateral distance between the vehicle lane edge of the host vehicle on the side opposite to the side where the vehicle exists and the obstacle is calculated as the degree of risk, and the steering control means, when the lateral distance is equal to or greater than the width of the host vehicle Only the application of the steering force in the direction of approaching the obstacle in the first control mode is stopped, and the first control mode and the second control are performed when the lateral distance is smaller than the width of the host vehicle. Direction to approach the obstacle by mode A lane departure prevention apparatus characterized by stops the steering force applied.
A third aspect of the present invention, the steering force in the first control mode to claim 1 or claim 2 characterized in that it is calculated by using the high-order function of the secondary or higher with respect to the lateral displacement It is a lane departure prevention apparatus of description.

According to a fourth aspect of the present invention, there is provided friction coefficient detecting means for detecting a friction coefficient of a road surface, and the steering control means is configured to detect the steering force with respect to the lateral displacement in the first control mode in response to a decrease in the friction coefficient. The lane departure prevention device according to any one of claims 1 to 3 , wherein the gain of the lane is reduced.
According to a fifth aspect of the present invention, there is provided friction coefficient detecting means for detecting a friction coefficient of a road surface, and the steering control means is configured to reduce the pulsed steering force in the second control mode in response to a decrease in the friction coefficient. The lane departure prevention device according to any one of claims 1 to 4 , wherein the lane departure prevention device is reduced.

According to the present invention, the following effects can be obtained.
(1) By having a first control mode that applies a steering force according to an increase in lateral displacement of the host vehicle when a departure tendency is not determined, the steering force is applied before the vehicle has a departure tendency. It is possible to suppress the occurrence of deviation tendency. Also, by having a second control mode that applies a pulsed steering force when a departure tendency is determined, the driver is warned when a departure tendency occurs and a steering operation toward the center of the lane is urged. it can. Furthermore, even if a tendency to deviate occurs, safety can be ensured by the second control mode. Therefore, the first control mode does not need to have a strong support level to surely prevent the deviation, and the driver's steering operation Interference can be reduced.

(2) The steering force in the first control mode is calculated using a higher-order function of the second or higher order with respect to the lateral displacement, so that the steering force and the rate of increase of the steering force with respect to the lateral displacement are calculated at the center of the lane. Since it can be made smaller, it is difficult for the driver to interfere with the steering operation. In addition, the steering force and the rate of increase thereof increase in accordance with the increase in lateral displacement, so that when the lateral displacement increases, a certain amount of steering force can be generated, and the departure prevention effect can be enhanced. Further, since such control makes it difficult for the driver to be aware that control is being performed at the center of the lane, lane departure can be prevented so that the driver does not notice.

(3) By reducing the gain of the steering force with respect to the lateral displacement in the first control mode in accordance with the decrease in the friction coefficient, an excessive steering force is generated on a slippery road surface and the behavior of the vehicle becomes unstable. Can be prevented.
(4) By reducing the pulsating steering force in the second control mode in accordance with the reduction in the friction coefficient, an excessive steering force is generated on a slippery road surface to prevent the behavior of the vehicle from becoming unstable. it can.

(5) Steering of the driver who tries to avoid the obstacle by stopping the application of the steering force in the direction of approaching the obstacle according to the first control mode when the approaching degree of the obstacle is higher than a predetermined value. Interference with operation can be prevented.
(6) When an obstacle exists outside the traveling lane of the host vehicle, the risk of collision with the obstacle can be appropriately detected by calculating the lateral distance between the lane edge and the obstacle as the danger level. .
(7) When an obstacle is in the lane of the host vehicle, the risk of collision at the time of passing through is detected appropriately by calculating the lateral distance between the lane edge on the anti-obstacle side and the obstacle as the risk. can do. Then, when it is possible to pass through without departing from the lane, by stopping only the first control mode, the driver can avoid an obstacle without feeling interference with the steering control. In addition, when it is impossible to pass through without deviating from the lane, it is estimated that an intentional deviating operation is performed, and the first and second control modes are stopped so that the driver can perform the steering control. You can deviate from the lane without feeling any interference.

  An object of the present invention is to provide a lane departure prevention device that reduces interference with a driver's operation and prevents a lane departure in advance. In the lane, a steering torque corresponding to the cube of the lateral position deviation of the host vehicle is provided. The problem is solved by performing the first control to be applied and performing the second control to apply a pulsed steering torque when the vehicle deviates.

Embodiments 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 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.
The lane departure prevention device applies a steering torque (steering force) to the steering mechanism 10 in order to warn the driver of the departure and return the vehicle toward the center of the lane when the departure tendency of the host vehicle from the traveling lane is determined. It is given.
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 pushes and pulls the knuckle arm of the housing H to rotate the housing and perform steering.

  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.

The lane departure prevention apparatus of the embodiment includes a departure prevention control unit 100 described below.
The 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, for example. Various information and signals can be acquired.
The departure prevention control unit 100 includes an environment recognition unit 110, a target travel position setting unit 120, a host vehicle traveling path estimation unit 130, a departure determination unit 140, an obstacle detection unit 150, an approach degree calculation unit 160, and a friction coefficient detection unit. 170, steering control means 180, 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 environment ahead of the host vehicle based on image information obtained by imaging the front of the host vehicle, and sets the traveling lane of the host vehicle. The environment recognition unit 110 functions as a lane setting unit according to the present invention.
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 environment recognizing means 110 sets the traveling lane of the host vehicle by recognizing 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 host vehicle and the travel lane.
The environment recognizing means 110 detects the white line WL portion from the reference image data based on the luminance data of each pixel corresponding to the location on the road surface. 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. And the position of a white line is detected by calculating the distance of the pixel group of the said white line part using the parallax mentioned above.

The environment recognizing means 110 continuously detects the position of the white line, sets a plurality of lane candidate points P _L in the traveling direction of the vehicle, ignores the lane candidate points P _L that cannot be matched, A lane shape in front of the host vehicle is recognized by performing a complementary process using least square approximation.
Here, the white line WL is approximated by Equation 1 below.

y = ax ² + bx + c (Expression 1)
a, b, c: constants

Here, c indicates the distance from the center of gravity of the host vehicle to the left and right lane edges, and the sum of c (C_right) on the right white line and c (C_left) on the left white line indicates the lateral deviation Δe from the center of the lane of the host vehicle. These differences indicate the lane width Xw.

  The target travel position setting unit 120 sets the target travel position Xc at the center of the white line WL on the left and right lanes set by the environment recognition unit 110.

The own vehicle traveling path estimation means 130 is based on 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, etc., and known vehicle specifications. The traveling path of the host vehicle is estimated.
The vehicle traveling path is estimated by, for example, calculating the lateral position of the vehicle at a gaze distance Z that is a predetermined distance ahead of the vehicle. The gaze distance Z is a predetermined distance in front of the host vehicle, and is set, for example, at a position where the host vehicle reaches several seconds later (for example, about 2 seconds).
The following description will be made using a coordinate system having the center of gravity of the host vehicle as the origin, the X axis extending in the vehicle width direction, and the Z axis extending forward of the vehicle body.
The lateral position Xe of the own vehicle traveling path at the gaze distance Z is obtained by the following formula 2.

The departure determination unit 140 uses the host vehicle traveling path estimation unit 130 to determine the departure tendency of the host vehicle OV from the traveling lane set by the environment recognition unit 110.
FIG. 3 is a diagram illustrating an example of a planar arrangement of the host vehicle and the traveling lane in departure determination. Here, the host vehicle OV illustrated in FIG. 3 indicates the estimated position at the gaze distance Z.
The departure determination unit 140 obtains a lateral deviation Δe with respect to the target travel position Xc of the host vehicle OV from the lateral position Xe of the host vehicle at the gaze distance Z estimated by the host vehicle traveling path estimation unit 130, and based on the lateral deviation Δe. The departure determination is established when the obtained position of the side edge of the vehicle deviates from the lane set by the environment recognizing means 110 (straddles either the left or right white line WL).

The obstacle detection means 150 detects the shape, size, lateral position and distance of the obstacle ahead of the host vehicle using the image information acquired by the environment recognition means 110.
The approach degree calculating means 160 calculates the lateral position of the obstacle detected by the obstacle detecting means 150 with respect to the host vehicle travel lane as an approach degree that is an index indicating the risk of collision risk. The calculation of the degree of approach will be described in detail later.

  The friction coefficient detection means 170 detects the friction coefficient (μ) of the road surface on which the host vehicle OV is traveling. As the friction coefficient detection means 170, for example, known parameters using various parameters such as vehicle speed, steering wheel angle, yaw rate, and a given vehicle motion model can be used, but the method for detecting the road surface friction coefficient is particularly limited. Not.

The steering control means 180 performs steering control for applying the steering torque to the steering mechanism 10 by controlling the electric power steering device using the above-described means.
The steering control includes lane departure prevention control for returning the host vehicle OV to the lane center side in order to prevent the departure in accordance with the departure tendency of the host vehicle OV from the traveling lane.
The lane departure prevention control has a first stage lane departure prevention control (first control mode) and a second stage lane departure prevention control (second control mode), and the basic steering torque in each stage control. The value is set based on the lateral deviation Δe from the target travel position of the host vehicle.
FIG. 4 is a graph showing the correlation between the lateral deviation and the steering torque in the lane departure prevention control. 4A shows the first-stage lane departure prevention control, and FIG. 4B shows the second-stage lane departure prevention control. In both FIG. 4A and FIG. 4B, the horizontal axis indicates the lateral deviation Δe, and the vertical axis indicates the target steering torque.

また、Δｅ＞Ｘｗ／２の場合には、操舵トルクＴｃは、所定の一定値であるトルクリミット値Ｔ_ｌｉｍ（Δｅ＝Ｘｗ／２のときの値）にガードされる。 In the first-stage lane departure prevention control, the steering torque Tc is calculated using Equation 3 below when Δe ≦ Xw / 2 (Xw is the lane width). The first-stage lane departure prevention control prevents the lane departure from occurring without giving the driver much awareness of steering assistance by applying a steering torque Tc that increases in proportion to the cube of the lateral deviation Δe. It is.

When Δe> Xw / 2, the steering torque Tc is guarded to a torque limit value T _lim (a value when Δe = Xw / 2) which is a predetermined constant value.

なお、操舵制御手段１８０は、摩擦係数検出手段１７０によって、路面の摩擦係数低下が検出された場合には、第１段階、第２段階の車線逸脱防止制御の操舵トルクを、ともに摩擦係数の低下量に応じて低下させる。第１段階の車線逸脱防止制御の操舵トルクの低下は、ゲインＧ_ｃを低下させることによって行う。
さらに、操舵制御手段１８０は、運転者によるウインカ操作時や、急制動、急操舵等に基づく緊急回避状態の判定時には、運転者の操舵操作との干渉を防止するため、操舵制御を停止する。また、図示しない路面カント検出手段により、路面カント（横方向傾斜）が検出された場合には、勾配を上る方向への操舵トルクを強め、下る方向への操舵トルクを弱める補正を行う。
以下、車線逸脱防止制御について、より詳細に説明する。 In the second lane departure prevention control, the steering torque Tp is uniformly set to zero when Δe ≦ Xw / 2 (Xw is the lane width). Further, in the case of Δe> Xw / 2, the steering torque Tp is set to a constant magnitude as shown in the following expression 4, and this is repeatedly turned on and off at a constant cycle. In the second stage of lane departure prevention control, after a departure tendency occurs, a pulsed steering torque is applied to vibrate the steering wheel 11 to warn the driver of the departure and prompt the steering operation toward the center of the lane. Is.

When the friction coefficient detection means 170 detects a decrease in the friction coefficient of the road surface, the steering control means 180 decreases the friction coefficient of the steering torque for the first and second lane departure prevention control. Decrease depending on the amount. Lowering of the steering torque of the lane departure prevention control in the first step is carried out by reducing the gain G _c.
Furthermore, the steering control means 180 stops steering control in order to prevent interference with the driver's steering operation when the driver performs a blinker operation or when determining an emergency avoidance state based on sudden braking, sudden steering, or the like. In addition, when a road surface cant (lateral inclination) is detected by a road surface cant detection unit (not shown), correction is performed to increase the steering torque in the upward direction and weaken the steering torque in the downward direction.
Hereinafter, the lane departure prevention control will be described in more detail.

FIG. 5 is a flowchart showing lane departure prevention control in the lane departure prevention apparatus of the embodiment. Hereinafter, the steps will be described step by step.
<Step S01: Environmental recognition>
The environment recognition unit 110 sets the travel lane OL of the host vehicle OV from the image information ahead of the host vehicle, and measures the lateral position Xe of the host vehicle OV and the lane width Xw of the travel lane.
Thereafter, the process proceeds to step S02.
<Step S02: Steering Torque Calculation in First Stage Lane Departure Prevention Control>
The steering control means 180 calculates the steering torque Tc in the first-stage lane departure prevention control based on the lateral position Xe of the host vehicle using the above-described equation 3, and proceeds to step S03.

<Step S03: Judgment of lateral deviation>
The steering control means 180 cooperates with the departure determination means 140, and the lateral deviation Δe, which is a deviation amount of the lateral position Xe with respect to the target travel position Xc of the host vehicle OV, is equal to or greater than Xw / 2, which is half the lane width. (Lane departure) is determined, and if Xw / 2 ≦ Δe, the process proceeds to step S04, and if Xw / 2> Δe, the process proceeds to step S06.

<Step S04: Steering Torque Calculation in Second Stage Lane Departure Prevention Control>
The steering control means 180 calculates the steering torque Tp in the second-stage lane departure prevention control based on the lateral position Xe of the host vehicle using the above-described equation 4, and proceeds to step S05.
<Step S05: First and Second Stage Steering Torque Addition>
The steering control means 180 adds the steering torque Tc in the first-stage lane departure prevention control calculated in step S02 and the steering torque Tp in the second-stage lane departure prevention control calculated in step S04, and then proceeds to step S06. move on.
<Step S06: Electric power steering control instruction output>
The steering control means 180 outputs a control instruction to the EPS control unit 20 based on the steering torque added in step S05, drives the electric actuator 21 to apply the steering torque to the steering mechanism 10, and ends the processing (return). )

Further, the lane departure prevention apparatus of the embodiment includes a first stop logic and a second stop logic that stop the first-stage lane departure prevention control described above. The first and second stop logics leave the second lane departure prevention control and only the first lane departure prevention control when the driver wants to drive while intentionally changing the lateral position in the lane. Is to stop.
The first stop logic is to stop the first-stage lane departure prevention control when an object in which the driver feels a risk exists outside the travel lane of the host vehicle OV.
Examples of the object that feels a risk include a vehicle such as a large vehicle traveling in an adjacent lane, and a building such as a wall, pole, or building adjacent to the traveling lane.
The second stop logic is to stop the first-stage lane departure prevention control when there is a small obstacle in the travel lane that allows the host vehicle OV to pass through.
Examples of the small obstacles include a parked vehicle partially extending over the traveling lane of the host vehicle OV across a white line, a motorcycle, a bicycle, a pedestrian, etc. existing near the lane edge.

First, the first stop logic will be described.
FIG. 6 is a diagram illustrating an example of a planar arrangement of the host vehicle, a traveling lane, and an obstacle when the first stop logic is applied.
FIG. 7 is a flowchart showing the first stop logic. Hereinafter, the steps will be described step by step in FIG.
<Step S11: Determination of Stop Time Control Timer Value>
The steering control means 180 determines whether the stop time control timer value T is greater than 0. If T> 0, the process proceeds to step S19, and otherwise, the process proceeds to step S12.
The stop time control timer value T is a timer value indicating the time elapsed after stopping the first-stage lane departure prevention control in either the left or right direction, depending on the elapsed time from the initial value T_init described later. Decrease.

<Step S12: Environmental recognition>
The obstacle detection means 150 and the approach degree calculation means 160 use the environment recognition means 110, and when there is an adjacent vehicle NV that travels in an adjacent lane NL adjacent to the travel lane OL of the host vehicle OV, the adjacent vehicle NV Next, the distance d from the vehicle end of the adjacent vehicle NV to the adjacent lane NL lane end is measured.
Thereafter, the process proceeds to step S13.
<Step S13: Adjacent vehicle presence / absence determination>
The steering control unit 180 proceeds to step S14 when the obstacle detection unit 150 detects the adjacent vehicle NV, and ends (returns) the process when not detected.
<Step S14: Adjacent vehicle lane edge approach situation determination>
The steering control means 180 determines whether the distance d from the vehicle end of the adjacent vehicle NV measured in step S12 to the adjacent lane NL lane end is a predetermined threshold value (for example, 0.2 m) or less. If d is smaller than 0.2 m, the process proceeds to step S15; otherwise, the process ends (returns).

<Step S15: Adjacent vehicle direction determination>
The steering control means 180 uses the obstacle detection means 150 or the like to determine whether the adjacent vehicle NV is traveling in the left or right lane with respect to the travel lane OL of the host vehicle OV.
If the adjacent vehicle NV is traveling in the right lane (X negative direction), the process proceeds to step S16. If the adjacent vehicle NV is traveling in the left lane (X positive direction), the process proceeds to step S17.
<Step S16: Stop the left first stage deviation prevention control>
The steering control means 180 stops the first-stage lane departure prevention control when the host vehicle OV deviates to the left (X positive side) of the travel lane OL.
Thereafter, the process proceeds to step S18.
<Step S17: Stop right first stage departure prevention control>
The steering control means 180 stops the first-stage lane departure prevention control when the host vehicle OV deviates to the right (X negative side) of the travel lane OL.
Thereafter, the process proceeds to step S18.
<Step S18: Initialization of Stop Time Control Timer Value>
The steering control unit 180 sets the initial value T_init to the stop time control timer value T, and ends (returns) the process.

<Step S19: First Stage Deviation Prevention Control Stop Continue>
The steering control means 180 continues to stop the first-stage lane departure prevention control stopped in step S16 or step S17. Thereafter, the process proceeds to step S20.
<Step S20: Stop Time Control Timer Value T Decrement>
The steering control means 180 subtracts 1 from the current value for the stop time control timer value T.
Thereafter, the process ends (returns).

Next, the second stop logic will be described.
FIG. 8 is a diagram illustrating an example of a planar arrangement of the host vehicle, the traveling lane, and the obstacle when the second stop logic is applied.
FIG. 9 is a flowchart showing the second stop logic. Hereinafter, the steps will be described step by step in FIG.
<Step S21: Determination of Stop Time Control Timer Value>
The steering control means 180 determines whether the stop time control timer value T is greater than 0. If T> 0, the process proceeds to step S31. Otherwise, the process proceeds to step S22.

<Step S22: Environmental recognition>
The obstacle detection means 150 and the approach degree calculation means 160 use the environment recognition means 110, and when there is an obstacle F that protrudes at least partially in the travel lane OL in front of the host vehicle OV, The lateral distance Wo between the side end point inside the traveling lane OL of the object F and the white line WL on the anti-obstacle F side of the traveling lane OL is measured.
Thereafter, the process proceeds to step S23.
<Step S23: Presence Object Presence Determination>
The steering control unit 180 proceeds to step S24 when the obstacle detection unit 150 detects an obstacle F (preceding object) ahead of the host vehicle, and ends (returns) the process when not detected.

<Step S24: Pass-through determination>
The steering control means 180 performs a slip-through determination that determines whether the host vehicle OV can pass through the obstacle F without departing from the travel lane OL.
Specifically, the vehicle width Wc of the host vehicle is compared with the distance Wo obtained in step S22. If Wc ≧ Wo, it is determined that the vehicle cannot pass through and the process proceeds to step S25. On the other hand, if Wc <Wo, it is determined that it can pass through, and the process proceeds to step S26.
<Step S25: First and Second Stage Lane Departure Prevention Control Stop Flag Set>
The steering control means 180 estimates that an intentional lane departure due to the driver's steering operation will occur, and sets a flag for stopping both the first-stage and second-stage lane departure prevention controls.
Thereafter, the process proceeds to step S27.
<Step S26: First Stage Lane Deviation Prevention Control Stop Flag Set>
The steering control means 180 estimates that the driver slips through the obstacle F by shifting the lateral position of the host vehicle OV in the travel lane OL, and sets a flag for stopping only the first-stage lane departure prevention control.
Thereafter, the process proceeds to step S27.

<Step S27: Obstacle Direction Determination>
The steering control means 180 uses the obstacle detection means 150 or the like to determine whether the obstacle F exists at the left or right end with respect to the travel lane OL of the host vehicle OV.
When the obstacle F exists on the right side (X negative direction), the process proceeds to step S28, and when it exists on the left side (X positive direction), the process proceeds to step S29.
<Step S28: Left-side departure prevention control stop>
The steering control means 180 stops the deviation prevention control when the host vehicle OV deviates to the left (X positive side) of the traveling lane OL according to the flag set in step S25 or S26.
Thereafter, the process proceeds to step S30.
<Step S29: Stop rightward departure prevention control>
The steering control means 180 stops the departure prevention control when the host vehicle OV deviates to the right (X negative side) of the travel lane OL according to the flag set in step S25 or S26.
Thereafter, the process proceeds to step S30.
<Step S30: Initialization of Stop Time Control Timer Value>
The steering control means 180 sets an initial value T_init for the stop time control timer value T, and ends (returns) the process.

<Step S31: Continue to stop the first stage departure prevention control>
The steering control means 180 continues to stop the lane departure prevention control stopped in step S28 or step S29. Thereafter, the process proceeds to step S32.
<Step S32: Stop Time Control Timer Value T Decrement>
The steering control means 180 subtracts 1 from the current value for the stop time control timer value T.
Thereafter, the process ends (returns).

According to the embodiment described above, the following effects can be obtained.
(1) When the departure tendency is not determined, by performing the first-stage lane departure prevention control that applies the steering torque according to the increase in the lateral deviation Δe with respect to the target travel position of the own vehicle OV, the own vehicle OV The application of the steering torque can be started before the departure occurs to prevent the departure. Also, by performing second-stage lane departure prevention control that applies pulse-shaped steering torque when a departure tendency is determined, the driver is warned when lane departure occurs and the steering operation toward the lane center side is urged Can do. Furthermore, even if a departure occurs, safety can be ensured by the second-stage lane departure prevention control, so the first-stage lane departure prevention control does not need to have a strong support level to reliably prevent the departure, Interference with the driver's steering operation can be reduced.

(2) The steering torque in the first stage lane departure prevention control is calculated by multiplying a value obtained by multiplying the deviation Δe to the third power by a predetermined gain, thereby reducing the increase rate of the steering torque with respect to the deviation Δe in the center of the lane. Therefore, it is difficult for the driver to interfere with the steering operation. Further, as the steering torque and the rate of increase thereof increase in accordance with the increase in the deviation Δe, when the deviation Δe increases, a certain amount of steering torque can be generated, and the deviation prevention effect can be enhanced. Further, since such control makes it difficult for the driver to be aware that control is being performed at the center of the lane, lane departure can be prevented so that the driver does not notice.

(3) By reducing the steering torque gain Gt with respect to the deviation Δe in the first-stage lane departure prevention control in accordance with the decrease in the friction coefficient, an excessive steering torque is generated on a slippery road surface and the vehicle behavior is not improved. It can prevent becoming stable.
(4) By reducing the pulse-like steering torque in the second stage lane departure prevention control according to the reduction in the friction coefficient, an excessive steering torque is generated on a slippery road surface and the behavior of the vehicle becomes unstable. Can be prevented.

(5) Avoid obstacles by stopping the application of steering torque in the direction of approaching obstacles by the first-stage lane departure prevention control when the distance of obstacles including adjacent vehicles is closer than a predetermined value. Interference with the driver's steering operation can be prevented.
(6) When the obstacle exists outside the traveling lane of the host vehicle, the risk of collision with the obstacle can be appropriately detected by calculating the lateral distance d between the lane edge and the obstacle as the danger level. it can.
(7) When an obstacle exists in the traveling lane of the host vehicle, the risk of collision at the time of passing through is appropriately calculated by calculating the lateral distance Wo between the lane edge on the anti-obstacle side and the obstacle as the danger level. Can be detected. Then, when it is possible to pass through without departing from the lane, by stopping only the first-stage lane departure prevention control, the driver can avoid the obstacle without feeling the interference with the steering control. In addition, when it is impossible to pass through without departing from the lane, it is estimated that the intentional departure operation is performed, and the driver stops the lane departure prevention control at the first stage and the second stage by stopping the driver. Can deviate from the lane without feeling any interference with the steering control.

(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) The method of calculating the steering torque in the lane departure control at each stage is not limited to the above-described embodiment, and can be changed as appropriate. For example, a feedback term other than the third-order term or a feed-forward term corresponding to the lane shape may be added to the first-stage steering torque calculation formula. Also, the setting of the second stage pulse-like steering torque is not limited to a constant value as in the embodiment.
(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 embodiment, when it is estimated that the side end portion of the host vehicle crosses the white line, the departure tendency is recognized and the departure determination is established, but the departure determination method and the reference are not limited to this and are appropriately changed. be able to. For example, the departure determination may be established when the distance to the lane edge is a predetermined threshold value or less. Further, not only the lateral position of the host vehicle but also the deviation tendency may be determined in consideration of the yaw angle and the lateral speed with respect to the lane.

It is a figure which shows the system configuration | structure of the vehicle containing the Example 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 and driving lane in the lane departure prevention apparatus of an Example. It is a figure which shows an example of the planar arrangement | positioning of the own vehicle and a travel lane in the departure determination of the lane departure prevention apparatus of an Example. It is a graph which shows the correlation with the lateral deviation of the own vehicle, and steering torque in the lane departure prevention control of the lane departure prevention apparatus of an Example. It is a flowchart which shows the lane departure prevention control in the lane departure prevention apparatus of an Example. It is a figure which shows an example of the planar arrangement | positioning of the own vehicle in the case of applying the 1st stop logic in the lane departure prevention apparatus of an Example, a travel lane, and an obstruction. It is a flowchart which shows the 1st stop logic in the lane departure prevention apparatus of an Example. It is a figure which shows an example of the planar arrangement | positioning of the own vehicle, driving | running | working lane, and obstruction in case the 2nd stop logic is applied in the lane departure prevention apparatus of an Example. It is a flowchart which shows the 2nd stop logic in the lane departure prevention apparatus of an Example.

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 integration unit 100 Deviation prevention control unit 110 Environment recognition unit 111 Stereo camera 112 Image processing unit 120 Target travel position setting unit 130 Auto Vehicle traveling path estimation means 140 Deviation determination means 150 Obstacle detection means 160 Approach degree calculation means 170 Friction coefficient detection means 180 Steering control means OV Own vehicle WL White line NV Adjacent vehicle F Obstacle OL Own vehicle travel lane NL Adjacent lane

Claims (5)

In a lane departure prevention device that applies a steering force to a steering mechanism so as to prevent a departure from the traveling lane of the host vehicle,
Lane setting means for acquiring environmental information in front of the host vehicle and setting the traveling lane of the host vehicle;
Target travel position setting means for setting a target travel position of the host vehicle in the travel lane;
Deviation determination means for determining a deviation tendency of the host vehicle from the travel lane based on a lateral positional relationship between the target travel position and the host vehicle;
A first control mode for applying the steering force in a direction to reduce the lateral displacement in response to an increase in lateral displacement of the host vehicle from the target travel position when it is determined that there is no departure tendency; Steering control means having a second control mode for applying the pulsed steering force when it is determined that there is a tendency ,
Obstacle detection means for detecting an obstacle ahead of the host vehicle;
An approach degree calculating means for calculating an approach degree of the obstacle to the own vehicle based on a lateral position of the obstacle with respect to the own vehicle;
Further comprising
The steering control unit stops applying the steering force in the direction of approaching the obstacle according to the first control mode when the approach degree is higher than a predetermined value;
When the obstacle is present outside the traveling lane of the host vehicle, the approach degree calculating means calculates a lateral distance between the obstacle and the obstacle in the traveling vehicle near the obstacle as the risk,
The steering control means only stops applying the steering force in the direction approaching the obstacle according to the first control mode when the lateral distance is equal to or less than a predetermined value.
Lane departure prevention apparatus according to claim.   In a lane departure prevention device that applies a steering force to a steering mechanism so as to prevent a departure from the traveling lane of the host vehicle,
  Lane setting means for acquiring environmental information in front of the host vehicle and setting the traveling lane of the host vehicle;
  Target travel position setting means for setting a target travel position of the host vehicle in the travel lane;
  Deviation determination means for determining a deviation tendency of the host vehicle from the travel lane based on a lateral positional relationship between the target travel position and the host vehicle;
  A first control mode for applying the steering force in a direction to reduce the lateral displacement in response to an increase in lateral displacement of the host vehicle from the target travel position when it is determined that there is no departure tendency; A steering control means having a second control mode for applying the pulsed steering force when it is determined that there is a tendency;
  With
  Obstacle detection means for detecting an obstacle ahead of the host vehicle;
  An approach degree calculating means for calculating an approach degree of the obstacle to the own vehicle based on a lateral position of the obstacle with respect to the own vehicle;
  Further comprising
  The steering control unit stops applying the steering force in the direction of approaching the obstacle according to the first control mode when the approach degree is higher than a predetermined value;
  When the obstacle is present in the traveling lane of the own vehicle, the approach degree calculating means calculates a lateral distance between the obstacle in the traveling lane of the own vehicle opposite to the side where the obstacle is present and the obstacle. Calculated as a risk,
  When the lateral distance is equal to or greater than the width of the host vehicle, the steering control means stops only applying the steering force in the direction approaching the obstacle in the first control mode, and the lateral distance is When the vehicle width is smaller than the width of the vehicle, stop applying the steering force in the direction of approaching the obstacle in the first control mode and the second control mode.
  A lane departure prevention device characterized by this. 3. The lane departure prevention device according to claim 1, wherein the steering force in the first control mode is calculated using a second-order or higher-order function with respect to the lateral displacement. Friction coefficient detection means for detecting the friction coefficient of the road surface is provided,
The steering control means decreases the gain of the steering force with respect to the lateral displacement in the first control mode in accordance with the decrease in the friction coefficient . The lane departure prevention apparatus according to item 1 . Friction coefficient detection means for detecting the friction coefficient of the road surface is provided,
The steering control means, with a decrease of the friction coefficient, to any one of claims 1, characterized in that lowering the pulsed steering force in the second control mode to claim 4 The lane departure prevention apparatus described .

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