JP2010100120A - Lane deviation prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lane deviation prevention device capable of generating the adequate steering torque according to the consciousness of a driver. <P>SOLUTION: The lane deviation prevention device for imparting the steering torque to a steering mechanism so as to prevent deviation of one's own vehicle from a running lane comprises a lane setting means 110 for setting the running lane of one's own vehicle by acquiring environmental information in front of one's own vehicle, an input torque detection means 140 for detecting the input torque by the steering operation of a driver, a deviation determination means 130 for determining the deviation tendency of one's own vehicle from the running lane, and a steering control means 170 for imparting the steering torque according to the input torque to the steering mechanism in the lane preventing direction when the deviation determination means determines the deviation tendency. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lane departure prevention apparatus that is provided in a vehicle such as an automobile and generates steering torque in accordance with a departure tendency from a traveling lane.

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

In the above-described lane departure prevention device, for example, when the driver intentionally performs a steering operation to depart from the lane to avoid an obstacle, the driver's It interferes with the operation and gives annoying feeling.
On the other hand, when the driver's awareness of driving is low and there is a high possibility that the driver is not aware of deviation, it is desirable to generate a higher steering torque to alert the driver.
The subject of this invention is providing the lane departure prevention apparatus which generate | occur | produces the appropriate steering torque according to a driver | operator's consciousness.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is a lane departure prevention apparatus that applies steering torque to a steering mechanism so as to prevent a departure from the traveling lane of the host vehicle, and obtains environmental information in front of the host vehicle and sets the traveling lane of the host vehicle. Lane setting means for performing the above operation, input torque detecting means for detecting an input torque due to a driver's steering operation, departure determining means for determining a departure tendency of the host vehicle from the traveling lane, and the departure determining means exhibit the departure tendency. A lane departure prevention apparatus comprising: a steering control unit that applies the steering torque according to the input torque to the steering mechanism in a direction to prevent departure when determined.

According to a second aspect of the present invention, there is provided steering angle detection means for detecting a steering angle by a driver's steering, and the steering control means is configured to control the steering torque according to a displacement amount of the steering angle when the steering torque is applied. The lane departure prevention device according to claim 1, wherein the lane departure prevention device according to claim 1 is corrected.
According to a third aspect of the present invention, there is provided a driver attention direction detecting means for detecting a driver's attention direction based on at least one of a driver's face direction and a line-of-sight direction; 3. The lane according to claim 1, further comprising an estimation unit, wherein the steering control unit increases the steering torque in accordance with a deviation amount of the direction of interest from the own vehicle traveling path. Deviation prevention device.
A fourth aspect of the present invention is the lane departure prevention apparatus according to any one of the first to third aspects, wherein the steering torque by the steering control means is pulsed.
Here, the pulsed steering torque may be either a single pulse or a continuous pulse, and the waveform of the steering torque is not particularly limited, such as a rectangular wave, a sine wave, and other waveforms.

According to the present invention, the following effects can be obtained.
(1) The magnitude of the steering torque applied when judging the departure tendency is set according to the input torque. When the input torque is large, the driver is highly conscious about driving and intentionally steers in the departure direction. By setting the steering torque to be small assuming that it is being performed, it is possible to reduce interference with the steering operation of the driver and to eliminate annoyance.
On the other hand, when the input torque is small, the driver is less aware of driving, and it is highly probable that the driver is not aware of the tendency to deviate. A tendency can be recognized with certainty and lane departure can be prevented.
(2) If the displacement of the steering angle when the steering torque is applied is large, it is assumed that the driver's steering force is small and the driver's consciousness is low, and the steering torque is increased so that the driver is more likely to deviate. It can be recognized with certainty.
(3) By increasing the steering torque in accordance with the amount of deviation of the driver's attention direction from the own vehicle traveling path, the driver can more reliably recognize the departure tendency when the driver is looking away. be able to.

  The present invention aims to provide a lane departure prevention device that generates an appropriate steering torque according to the driver's consciousness, in response to an increase in the output value of a torque sensor that detects input torque from the driver when determining a departure tendency. The problem was solved by reducing the pulsed steering torque applied to the steering mechanism.

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 front two 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 alerts the driver of the departure and returns the vehicle to the center of the lane when a tendency of the vehicle to depart from the driving lane is determined. Power).
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 steering 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 housing 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 TM 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.
Further, the departure prevention control unit 100 includes a lane setting unit 110, an own vehicle traveling path estimation / inference 120, a departure determination unit 130, an input torque detection unit 140, a steering angle detection unit 150, a direction of interest detection unit 160, a steering control unit 170, and the like. It is configured with. Each of these means may be configured as independent hardware, or part or all may be configured as common hardware.

The lane setting 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.
FIG. 2 is a diagram illustrating an example of a planar arrangement of the host vehicle, the traveling lane, and the host vehicle traveling path. The lane departure prevention apparatus according to the embodiment is configured to perform pulse-shaped steering in a direction in which the own vehicle is returned to the lane center side when the estimated traveling path of the own vehicle deviates from the traveling lane of the own vehicle sandwiched between the pair of white lines L. Torque is generated to alert the driver.
As shown in FIG. 1, a lane setting 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 processed image data to the lane setting 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 lane setting unit 110 detects 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 setting unit 110 sets the travel lane of the host vehicle by recognizing the shape of the white lines 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.
The lane setting means 110 detects the white line L 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 L 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 lane setting means 110 can continuously detect white line positions to 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 own vehicle traveling path estimation means 120 is based on the information from the lane setting means 110, the running state of the vehicle detected by the rudder angle sensor 22, the vehicle speed sensor 32, the yaw rate sensor 33, and the 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 1.

The departure determination unit 130 uses the host vehicle traveling path estimation unit 120 to determine a tendency of departure of the host vehicle from the traveling lane set by the lane setting unit 110.
The departure determination means 130 deviates from the lane set by the lane setting means 110 from the own vehicle side end position determined based on the lateral position Xe of the own vehicle at the gaze distance Z estimated by the own vehicle traveling path estimation means 120. In this case, departure judgment is established.

  The input torque detection means 140 acquires the output value of the torque sensor 23 through CAN communication with the EPS control unit 20. Based on the output value of the torque sensor 23, the input torque detection means 140 detects the input torque of the steering operation input to the steering wheel 11 by the driver.

  The steering angle detection means 150 acquires the output value of the steering angle sensor 22 through CAN communication with the EPS control unit 20. The steering angle detection means 150 detects the steering angle (the rotation angle of the steering wheel 11) in the steering mechanism 10 based on the output value of the steering angle sensor 22.

The attention direction detection means 160 detects the direction of the driver's line of sight as the attention direction by imaging the driver's face and performing image processing. The attention direction detection means 160 includes a driver camera 161 provided at the upper part of the steering column, for example.
The attention direction detection means 160 extracts the movement of the pupil position relative to the driver's face from the image captured by the driver camera 161, and detects the attention direction based on this.

The steering control means 170 uses the lane setting means 110, the own vehicle traveling path estimation means 120, the departure determination means 130, the input torque detection means 140, the steering angle detection means 150, the attention direction detection means 160, etc. When established, the electric actuator 21 is caused to generate a pulsed output steering torque via the EPS control unit 20. The steering control means 170 has a function of setting an output steering torque generated by the electric actuator 21.
The setting of the output steering torque and the operation when it is generated will be described in detail below.

FIG. 3 is a flowchart showing an operation at the time of setting and generating the steering torque in the vehicle departure prevention control. Hereinafter, the steps will be described step by step.
<Step S01: Deviation judgment determination>
The steering control unit 170 determines whether or not the departure determination by the departure determination unit 130 is established. If the departure determination is established, the process proceeds to step S02. Otherwise, the process ends (returns).

<Step S02: Input Torque Detection>
The steering control means 170 acquires information on the current input torque from the input torque detection means 140, and proceeds to step S03.
<Step S03: Driver attention direction detection>
The steering control unit 170 acquires information related to the current driver's attention direction from the attention direction detection unit 170, and the process proceeds to step S04.

<Step S04: Output Steering Torque Setting>
The steering control means 170 sets the output steering torque.
First, the steering control means 170 sets the basic value of the output steering torque based on the input torque detected in step S02.
FIG. 4 is a graph showing the correlation between the input torque and the basic value of the output steering torque. In FIG. 4, the horizontal axis indicates the input torque (output value of the torque sensor 22) _{St trq} , and the vertical axis indicates the output steering torque q.
As shown in FIG. 4, the output steering torque q is set so as to decrease almost inversely in proportion to the increase in the input torque S _trq . Note that, in a region where the input torque S _trq is small, the output steering torque q is guarded so as to be a predetermined upper limit value (a constant value).
Further, the steering control means 170 corrects the basic value of the output steering torque q described above based on the driver's direction of interest. Specifically, the direction of interest of the driver is compared with the direction of the own vehicle traveling path at a predetermined gaze distance, and when this deviation is greater than or equal to a predetermined threshold, correction for increasing the output steering torque q is performed.
Thereafter, the process proceeds to step S05.

<Step S05: Generation of steering torque>
The steering control means 170 gives an instruction to the EPS control unit 20, drives the electric actuator 21, and applies pulsed steering torque to the steering mechanism.
FIG. 5 is a graph showing an output waveform of the steering torque. FIG. 5A shows a case where the input torque is relatively large, and FIG. 5B shows a case where the input torque is relatively small.
The output waveform of the steering torque is, for example, a pulsed rectangular wave with an output time of about 100 msec. Then, as shown in FIGS. 5 (a) and 5 (b), the steering torque is set to decrease as the input torque increases.
Since the flow shown in FIG. 3 is repeatedly performed, the pulsed steering torque is repeatedly output as long as the departure determination is established.
Thereafter, the process proceeds to step S06.

<Step S06: Steering Angle Change Detection>
The steering control unit 170 acquires information regarding the change in the steering angle when the steering torque is applied to the steering mechanism 10 in step S05 from the steering angle detection unit 150. The change in the steering angle at this time is relatively small when the steering state of the steering wheel 11 by the driver is good, but is relatively large when the steering state is lowered due to, for example, a decrease in consciousness or doze. It is considered to be.
Thereafter, the process proceeds to step S07.

<Step S07: Output Steering Torque Setting Value Correction>
When the steering angle change after the steering torque application detected in step S06 is equal to or greater than a predetermined threshold, the steering control means 170 determines that the steered state is low and the driver's driving consciousness is low, and deviates. In order to make it recognized more reliably, the correction which increases the output steering torque setting value at the time of the next steering torque provision is performed, and a process is complete | finished (return).
As a result, if the departure determination continues to be established, a steering torque larger than the previous time is applied to the steering mechanism 10 when the pulse-shaped steering torque is applied next time.

According to the embodiment described above, the following effects can be obtained.
(1) When determining the departure tendency by the departure determination means 130, the magnitude of the steering torque applied to the steering mechanism 10 is set according to the input torque to the steering wheel 11, and if the input torque is large, the driver By setting the output steering torque to a small value based on the assumption that the driver is highly conscious of driving and intentionally steering in the direction of departure, the interference with the driver's steering operation is reduced and the annoyance is eliminated. can do. On the other hand, when the input torque is small, the driver is less conscious of driving, and it is highly likely that the driver is not aware of the departure tendency. The departure tendency can be recognized with certainty and lane departure can be prevented.
(2) When the displacement amount of the steering angle when the steering torque is applied to the steering mechanism 10 by the electric actuator 21 is large, it is assumed that the driver's steering force is small and the driver's consciousness is low, and the output steering from the next time onward. The torque can be increased to make the driver recognize the deviation tendency more reliably.
(3) By increasing the output steering torque according to the amount of deviation of the driver's attention direction from the own vehicle traveling path, the driver can more reliably recognize the departure tendency when the driver is looking away. Can be made.

(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 embodiment, the environment is recognized by the stereo camera. However, the present invention is not limited to this. For example, the information on the traveling lane of the own vehicle such as map data and GPS prepared for the navigation device is used. It is good also as a structure acquired from a positioning apparatus.
(2) 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, a double pinion type that drives a pinion independent of the pinion connected to the steering shaft, Also, it may be a rack linear motion type that drives the steering rack itself in the straight direction.
(3) The attention direction detection means of the embodiment detects the direction of the driver's line of sight, but is not limited thereto, and the direction of the driver's face may be detected and used as the attention direction.
(4) The departure determination means of the embodiment estimates the own vehicle traveling path and establishes the departure determination when the own vehicle traveling path deviates from the lane in front of the own vehicle. The departure determination may be performed by other methods. For example, the departure determination may be established when the current lateral position of the host vehicle enters a predetermined departure determination range.

It is a figure which shows the system configuration | structure of a vehicle provided with 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, a travel lane, and the own vehicle advancing path. 2 is a flowchart showing an operation at the time of setting and generation of steering torque in vehicle departure prevention control of the lane departure prevention apparatus of FIG. 1. It is a graph which shows the correlation with the basic value of the input torque and output steering torque in the lane departure prevention apparatus of FIG. It is a graph which shows the output waveform of the pulse-shaped steering torque in the lane departure prevention apparatus of FIG.

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 device 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 Deviation prevention control unit 110 Lane setting means 120 Own vehicle traveling path estimation means 130 Deviation judgment means 140 Input torque detection Means 150 Steering angle detecting means 160 Attention direction detecting means 161 Driver camera 170 Steering control means OV Own vehicle L White line

Claims (4)

In a lane departure prevention device for applying a steering torque 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;
An input torque detecting means for detecting an input torque due to a driver's steering operation;
Deviation determination means for determining a deviation tendency of the host vehicle from the traveling lane;
A lane departure prevention comprising: steering control means for applying the steering torque according to the input torque to the steering mechanism in a direction to prevent departure when the departure determination means determines the departure tendency. apparatus. A steering angle detection means for detecting the steering angle by the steering of the driver,
The lane departure prevention device according to claim 1, wherein the steering control unit corrects the steering torque according to a displacement amount of the steering angle when the steering torque is applied. A driver attention direction detection means for detecting a driver's attention direction based on at least one of a driver's face direction and a line-of-sight direction;
Own vehicle traveling path estimating means for estimating the own vehicle traveling path,
3. The lane departure prevention device according to claim 1, wherein the steering control unit increases the steering torque in accordance with a deviation amount of the attention direction from the own vehicle traveling path. The lane departure prevention apparatus according to any one of claims 1 to 3, wherein the steering torque by the steering control means is pulsed.

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