JPH1173596A - Traffic lane deviation prevention device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to guide an avoidance of a traffic lane deviation in a traffic lane deviation prevention device by imparting a steering control torque in accordance with a degree to which a vehicle tends to deviate from the traffic lane, a cant condition of a road surface or the like, without disturbing a driver's steering. SOLUTION: This device guide a prevention of a traffic lane deviation by making a steering actuator 21 impart a steering control torque of a degree to which a driver can simply overcome, apart from a steering torque for the driver in a direction for preventing his own vehicle from deviating from a traffic lane. In this case, the device is equipped with a slip quantity calculation means 4A for calculating the quantity of slip from a reference point of the running lane, a control torque calculation means 5 for calculating a control torque on the basis of the slip quantity and a control means 6 for control the steering actuator 21 so that the control torque is generated in a direction decreasing the slip quantity, and is provided with a control torque correction means 5A for correcting on the basis of cant information detected by a cant information detection means 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle which applies a steering control torque that the driver can easily overcome in addition to the steering torque applied by the driver in a direction to prevent the host vehicle from going out of the lane. The present invention relates to a lane departure prevention device for guiding prevention of lane departure.

[0002]

2. Description of the Related Art In recent years, there has been developed a technology (driving guidance device) for grasping the position and posture of a vehicle with respect to a traveling road, performing automatic traveling control of a vehicle based on the grasp, and guiding a driver to drive. Is being developed. In the case of automatic cruise control, it is necessary to drive a car without relying on the driver at all, and various conditions such as the development of basic facilities (infrastructure) such as roads are premised on the practical application. Become.

[0003] On the other hand, in the case of a driving guide device, it is the driver who drives the vehicle, and the driving guide device informs the driver of a driver's driving error and assists the driver in the direction to eliminate the mistake. It is. Therefore, the driving guidance device has many technologies that can be realized even in the current road environment, and it is desired to develop a driving guidance device with higher practicality.

[0004] One of such driving guide devices is a lane departure prevention device. As this lane departure prevention device, there is a technology (Japanese Patent Laid-Open No. 63-214900) that issues a warning to a driving vehicle when the vehicle is inadvertently deviating from the traveling lane. However, simply issuing a warning may not be effective for a driver who is dozing off. Therefore, the steering control is more positively performed so that the vehicle travels at a certain position (for example, the center position) in the traveling lane. Technology (Japanese
-270005) has also been proposed.

Further, in the case where the vehicle is controlled so as to maintain a fixed position in the traveling lane as described above, when the vehicle attempts to protrude from the traveling lane due to a temporary steering abnormality such as careless steering by a driver. If this control works, it may cause a buffer with other vehicles. For this reason, in such a case, instead of returning the vehicle to a certain position in the traveling lane, a technique of performing steering control so as to maintain a position biased to the side where the vehicle is going to protrude even in the traveling lane ( Japanese Patent Application Laid-Open No. 5-297939 is also proposed.

[0006]

By the way, in the case of the lane departure prevention device which is one of the driving guide devices as described above,
In order to prevent the vehicle from deviating from the driving lane, it is necessary to apply a steering control torque through a steering actuator separately from the steering torque applied by the driver, but the steering control torque to be applied in this case is too small. The effect cannot be expected. On the contrary, if it is too large, the steering operation by the driver itself is hindered.

That is, the steering control torque for preventing the lane departure as the driving guide is for guiding the driver's steering operation or assisting the steering in the direction to eliminate the driver's steering error. And the subject to be steered is the driver. Therefore, the main purpose of the application of the steering control torque in this case is to inform the driver that the vehicle is about to deviate from the driving lane, and the steering torque for actually holding the vehicle in the lane is I want to be added by the driver itself.

[0008] In particular, it is difficult to accurately determine whether the vehicle is about to deviate from the driving lane against the driver's will. For example, if the vehicle is about to deviate from the predetermined range in the driving lane, it can be determined that the vehicle is likely to deviate from the driving lane unexpectedly. Therefore, when the vehicle tries to deviate from the traffic lane, it is determined that the vehicle is deviating from the traffic lane.

When a control torque is generated by the steering actuator based on such determination, the steering control is performed in a direction opposing the driver's steering operation when the driver intends to depart from the traveling lane. If the steering control torque is too large, it will support the steering operation such as lane change by the driver's intention, and from this point too, make sure that the steering control torque does not become excessive. Want to.

In addition, when such a steering control torque is applied, it is generally considered that the driver responds according to the magnitude of the steering control torque. That is, it is considered that if the steering control torque is increased, the driver relatively quickly performs the steering operation to avoid the lane departure. For this reason, the magnitude of the steering control torque does not merely become excessive, but also depends on the degree to which the vehicle is going to deviate from the traveling lane (for example, the amount of lateral displacement of the vehicle from the reference position of the traveling lane). Things to do
This is preferable for quickly and smoothly avoiding departure from the lane.

Further, the vehicle may be subjected to a lateral force depending on the road surface condition or running condition, and such a lateral force affects the steering of the vehicle. For example, generally on a curved road,
A cant is provided that is inclined sideways so that the road surface descends inside the curve. In such a cant, the gravity on the vehicle acts as a force on the inside of the turn (centripetal force). Therefore, the magnitude and direction of the steering control torque should be set in consideration of this point.

The present invention has been made in view of the above-described problems, and does not hinder a steering operation by a driver's intention, and is appropriate in accordance with the degree of the vehicle trying to deviate from the traveling lane and the cant situation on the road surface. It is an object of the present invention to provide a lane departure prevention device capable of accurately guiding a driver to avoid a lane departure by applying a steering control torque.

[0013]

Therefore, in the lane departure prevention apparatus according to the first aspect of the present invention, the lateral deviation calculating means calculates the lateral deviation of the traveling position of the vehicle from the reference position of the traveling lane. The control torque calculating means calculates the steering control torque based on the lateral displacement calculated by the lateral displacement calculating means. At this time, the control torque correcting means of the control torque calculating means further corrects the control torque calculated based on the lateral deviation amount based on the road surface cant information detected by the cant information detecting means, and converts the control torque into the lateral deviation amount and the cant information. Based on this, a steering control torque that is large enough for the driver to easily overcome is set.

The control means controls the steering actuator of the vehicle such that the control torque set by the control torque calculation means is generated in a direction to reduce the lateral displacement amount. In this way, the steering control according to the amount of lateral displacement of the vehicle and the cant state of the road surface is such that the driver can easily overcome the steering torque applied by the driver in a direction to prevent the vehicle from deviating from the traveling lane in a direction to prevent the deviation. Torque is applied by the steering actuator to guide the prevention of lane departure of the vehicle.

Further, in the lane departure prevention apparatus according to the present invention, the lateral deviation calculating means calculates the lateral deviation of the traveling position of the own vehicle from the reference position of the traveling lane, and the control torque calculating means comprises: The steering control torque is calculated based on the lateral displacement calculated by the lateral displacement calculating means. At this time, theoretical lateral acceleration generated in the own vehicle is calculated by the theoretical lateral acceleration calculating means based on the steering angle detected by the steering angle detecting means and the vehicle speed detected by the vehicle speed detecting means. The deviation between the theoretical lateral acceleration calculated by the theoretical lateral acceleration calculating means and the actual lateral acceleration detected by the actual lateral acceleration detecting means is calculated, and the control torque correcting means of the control torque calculating means calculates the lateral deviation. The control torque is corrected based on the deviation calculated by the deviation calculating means, based on the amount of lateral displacement and the deviation between the theoretical lateral acceleration and the actual lateral acceleration, and is large enough for the driver to easily overcome. Set the steering control torque.

The control means controls the steering actuator of the vehicle such that the control torque set by the control torque calculation means is generated in a direction to reduce the lateral shift amount. With this, the driver can easily overcome the steering torque applied by the driver in a direction to prevent the vehicle from deviating from the traveling lane in a direction to prevent the vehicle from deviating from the driving lane. A steering control torque corresponding to the deviation is applied by a steering actuator to guide the prevention of lane departure of the vehicle.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lane departure prevention device according to an embodiment of the present invention; FIG.
The lane departure prevention device (also referred to as a lane guidance system) is provided to prevent the vehicle from deviating from the traveling lane in an automobile. When there is a possibility that the steering torque is different from the steering torque applied by the driver by the steering actuator 21 provided to the vehicle as shown in FIG. 1 (this steering torque is used to distinguish it from the steering torque applied by the driver). Control torque) to warn the driver during steering through a steering wheel (hereinafter also referred to as a steering wheel) 20 of a lane departure.

Of course, the steering control torque itself is also
The main purpose of this steering control torque is to warn the driver through the steering system, and to correct the position of the vehicle that is likely to deviate from the lane. It should be performed by the driver's steering operation that recognizes that the vehicle is likely to depart from the lane due to the application of the control torque.

Therefore, the present lane departure prevention device is shown in FIG.
As shown in FIG. 1, in order to recognize the position of the host vehicle with respect to the traveling lane, a camera 2 as an image pickup means for picking up an image of a road condition ahead of the vehicle 1 and image information from the image information from the camera 2 are appropriately processed. Information processing means 3 for recognizing left and right white line positions on a front road, and a lateral shift amount ΔY for calculating a lateral shift amount ΔY with respect to a reference position of a traveling lane (traveling lane) of the vehicle from the white line position image information by the image information processing means 3 It has an amount calculating means 4A.

It should be noted that the lateral deviation amount ΔY corresponds to a determination parameter relating to the degree that the vehicle 1 is likely to depart from the lane. The lateral displacement amount calculating means 4A is provided as a functional element in the traveling lane estimating means 4 for estimating the relative position of the traveling lane (traveling lane) with respect to the own vehicle. Further, the present lane departure prevention device is provided with the lateral displacement amount calculating means 4A.
Is calculated based on the lateral deviation amount (lateral deviation) ΔY, that is, the degree of departure from the lane.
c, a steering actuator 21 capable of applying a steering control torque to the steering system separately from the steering torque applied by the driver, and a steering control torque Tc calculated by the control torque calculation unit 5. Is the amount of lateral shift Δ
Steering actuator 2 so that it occurs in the direction to decrease Y
1 is provided with control means (controller) 6 for controlling the control unit 1.

Further, a switch (SW) 23 for selecting the operation of the lane departure prevention device is provided. Therefore, if you want to operate this device, turn on the switch 23,
If you do not want to operate this device, turn off switch 23,
It can be selected according to the driver's preference.
Further, for example, in the instrument panel (instrument panel), when the switch 23 is turned on or when a control torque for preventing lane departure is applied, an operation display unit 24 for displaying the control torque is provided. I have.

The image information processing means 3, the traveling lane estimating means 4 (lateral displacement calculating means 4A), the control torque calculating means 5, and the controller 6 are electronic control units including a CPU, an input / output interface, a ROM, a RAM, and the like. It is configured as a unit. First, recognition of the position of the own vehicle with respect to the traveling lane, that is, calculation of the lateral deviation amount ΔY of the own vehicle will be described.

As shown in FIG. 2, the image information processing means 3 first takes in an original image 41 from the camera 2, extracts a road white line from the original image 41, and converts the extracted road white line image into a vertical image. The image is converted into a two-dimensional image 42 as viewed from above. Next, the recognition of the white lines 12L and 12R is shown in FIG.
This will be described with reference to FIG. Here, the recognition of the white line 12L as the roadside line at the left end of the traveling lane will be described. However, the same applies to the case where the white line 12R at the right end of the traveling lane is used as a reference. I will call it.

Next, in the image information recognizing means 3, FIG.
As shown in FIG. 1A, a camera 2 provided on a vehicle 1 uses a camera 2 to cover a flat area (eg, 5 m to 30 m).
m), the image in the vertical direction on the screen is partially omitted from the image information. Then, a plurality of horizontal lines 11 are set at equal intervals on this screen. The capture of the black-and-white image information is updated every minute control cycle. As shown in FIG. 3B, on each horizontal line 11, the left and right positions of the white line position on the previous screen are required. (Here, the left and right 50 pixels [do
t]) is set as a white line search area (processing target area) 10. For the first screen, the white line position on the straight road is used as the previous screen data.

Then, as shown in FIG. 3C, the brightness of each horizontal line is differentiated in the horizontal direction from the left. Reference numeral 14 in the figure is a guardrail. By the way, a normal road surface has low luminance and a small change in luminance. On the contrary,
Since the brightness of the white line 12 is much higher than that of the normal road surface, when the brightness of the road is differentiated in this way, the luminance change is positive at the boundary point from the normal road surface to the white line 12, and the white line 12 changes to the normal road surface. Differential data is obtained such that the luminance change becomes negative at the boundary point of. An example of such differential data is shown in FIG.

Then, for each of the data of each horizontal line 11, peaks of the differential values appear in the order of plus and minus from the left, and the interval between the peaks is the white line 12.
Is extracted as a candidate for a white line, and a combination that falls within a reasonable degree (interval between a positive peak and a negative peak is within 30 dots, for example) is extracted.
As shown in FIG. 3E, the midpoint M is set to the white line candidate point 15.
Save as

Then, among these white line candidate points 15,
Only the point closest to the screen center is left as the final candidate point.
This means that, for example, when the vehicle 1 is traveling on the left side, the search area 1
The right side of 0 is a road surface with little change in normal luminance, and the white line candidate point 15 closest to this normal road surface can be determined as the white line 12. Therefore, further to the left of the white line 12,
Objects that cause noise (for example, guardrails 14)
Is present, the white line 12 can be reliably recognized from the image information captured by the camera 2.

Finally, as shown in FIG. 3F, the vertical continuity of the white line candidate points 15 in each horizontal line data is sequentially verified from the bottom of the screen. First, the inclination between the upper and lower ends of the white line 12 on the previous screen is calculated in advance.
Then, assuming that the lowest point 15A is the white line 12, it is verified whether or not the candidate point 15B on the horizontal line 11 which is only one line above is within the range of ± 50 dots of the inclination of the previous white line 12.

If the candidate point 15B falls within this range, it is regarded as a white line. If not, the candidate point 15B is rejected, and the coordinates obtained by interpolation from the above-mentioned inclination are regarded as the white line position. By performing the same operation for each horizontal line for this detection, a continuous white line 12 can be recognized. Such white line recognition work is continuously performed at a required cycle, and the recognition of the white line 12 is updated each time.

The white line 12 as the roadside line at the right end of the traveling lane
The recognition of R is performed in the same manner. In the estimating means 4, the original image 41 thus recognized in each recognition cycle
The upper white lines 12R and 12L are converted into a two-dimensional image 42,
Based on the road centerline LC _R from traveling lane left to the road central line LC _L which can be estimated from the white line 12L traveling lane right edge of the white line 12R can estimate, by performing estimation of a road center line LC, the center line of the road Lateral deviation amount ΔY based on LC
And the argument β.

The declination β is, as shown in FIG. 4, the angle between the tangent to the curved road center line LC and the vehicle center line direction, and is the first detection point ( It is calculated from reference line position information at a perigee in the figure) and reference line position information at a second detection point (shown as apogee in the figure) further away from the vehicle 1 by a predetermined amount from the perigee. be able to.

That is, the declination β is calculated as an angle between a straight line connecting the first detection point and the second detection point and the center line of the vehicle 1. The declination calculated in this way is a declination at an intermediate point between the first detection point and the second detection point (indicated by x in the drawing), and is a declination at least a point ahead of the vehicle 1 by a certain distance or more. . In this example, the point closest to the vehicle on the road center line LC based on the image information from the camera 2 is set as the first detection point, and the position between the own vehicle center line and the road center line LC at the first detection point is determined. The directional distance (the road width direction, the lateral distance of the camera image) is calculated as the lateral deviation amount (lateral deviation) ΔY. Further, the curve radius R is estimated based on the calculated declination β.

The control torque calculating means 5 calculates the steering control torque Tc based on the amount of lateral displacement of the vehicle with respect to the reference position (the center position of the road width) of the traveling lane thus calculated.
In this apparatus, the steering control torque Tc
There is a feature in the setting. That is, the steering control torque T
c is different from the steering torque used for automatic steering, and its main purpose is to warn the driver. Since the position of the vehicle is corrected by the driver's steering operation, the steering control torque Tc is determined by the driver's steering torque. It is limited to a size that does not hinder the operation, that is, a size that the driver can easily overcome.

Therefore, even when the steering control torque Tc is applied in a direction to avoid the departure when the vehicle is likely to deviate from the lane, it is sufficient if the driver performs the steering operation in the direction deviating from the lane. You can do this. As a result, emergency steering for retreating the vehicle out of the travel lane can be easily performed, and even if the steering control torque Tc is applied at the time of lane change, it does not hinder lane change. .

Further, the steering control torque Tc is set to a magnitude corresponding to the lateral shift amount ΔY of the vehicle. That is, as shown in FIG. 5, the control torque calculating means 5 sets the steering control torque Tc so as to be proportional to the lateral shift amount ΔY. In FIG. 5, the abscissa regarding the lateral deviation amount ΔY indicates a lateral deviation to the right in the right direction and a lateral deviation to the left in the left direction. The left direction indicates the left steering to guide the vehicle to the right side of the lane.

As shown in FIG. 5, if the vehicle shifts to the right from the road center line, a left steering control torque Tc for guiding the vehicle to the left side of the lane is set according to the lateral shift amount ΔY. If the vehicle shifts from the left to the right, a control torque Tc for right steering that guides the vehicle to the right side of the lane is set according to the lateral shift amount ΔY. However, in each case, the magnitude of the control torque Tc is limited to a constant value Tcm. Here, when the magnitude of the lateral deviation amount ΔY becomes Y1, the magnitude of the control torque Tc is limited to a constant value Tcm. This limits the driver to a size that can be easily overcome, as described above.

Further, the control torque calculating means 5 includes control torque correcting means 5A for correcting the steering control torque Tc calculated from the lateral deviation amount ΔY based on the lateral inclination of the road surface of the traveling lane, ie, the cant information. I have. Further, a cant information detecting means 7 is provided for inputting cant information to the control torque correcting means 5A. In the cant information detecting means 7 of the present embodiment, detection information from a lateral acceleration sensor (lateral G sensor) 31, a vehicle speed sensor 32, and a steering angle sensor 33 [ie, actual lateral acceleration (actual lateral G), vehicle speed V, steering angle θth], a lateral acceleration deviation (lateral G deviation) ΔGy, which is a deviation between the calculated lateral acceleration (calculated lateral G) and the actual lateral acceleration (actual lateral G), is calculated as a value corresponding to the cant. The G deviation ΔGy is output as cant information. The actual lateral G can use the detection information of the lateral G sensor 31, and the lateral G deviation ΔGy and the calculated lateral G are calculated by the following equations.

ΔGy = calculated width G−actual width G (1) Gyc = [θth / (r · g)] × [(V ² / HB) / (1 + SF × V ² )] (2) Gyc: calculated lateral G, θth: steering angle, r: steering gear ratio, g: gravitational acceleration, V: vehicle speed, HB: vehicle wheelbase, SF: stability factor.

The reason why the lateral G deviation ΔGy is used as the cant information is as follows. That is, when the vehicle is turning, a lateral G (actual lateral G) occurs in the vehicle. The actual lateral G is calculated from the steering angle θth and the vehicle speed V from the formula (2) if the road surface is flat (cant is 0) without causing the tire to skid more than the normal range. Real horizontal G
Is almost equal to However, if a cant is provided on the road surface, the vehicle can turn with a relatively small steering angle even on a curved road having the same curvature. Therefore, if the cant is provided, the calculation width G becomes smaller by that amount,
Accordingly, the lateral G deviation ΔGy becomes small (negative value).

Here, as for the lateral G deviation ΔGy, the calculated lateral G, and the actual lateral G, the outside of the turn is positive and the inside of the turn is negative (the setting of the sign may be reversed).
As described above, when the vehicle is turning on a curve with a cant, the magnitude of the calculated lateral G is smaller than the magnitude of the actual lateral G, so that the lateral G deviation ΔGy is negative. Although it is almost impossible on a general road, if the cant is provided in reverse, the lateral G deviation ΔGy becomes positive.

The control torque correcting means 5A sets a cant correction coefficient Kc with the characteristics C1 and C2 as shown in FIG. 7 for the lateral G deviation ΔGy calculated in this manner, and calculates the deviation from the lateral deviation ΔY. The steering control torque Tc is multiplied by the cant correction coefficient Kc to obtain the steering control torque Tc.
c is cant corrected. In FIG. 7, the horizontal axis represents the lateral G deviation ΔGy, the vertical axis represents the cant correction coefficient Kc, and the characteristic C1 indicated by the solid line is laterally offset from the road center line LC with respect to the road center line LC. The characteristic C2 indicated by a broken line indicates that the vehicle is traveling on the road center line L
This is a case in which the vehicle is displaced laterally inward with respect to C.

In general, when traveling on a curve with a cant, the gravity acting on the vehicle according to the cant acts in a direction to assist the turn, so that the steering control torque for the inside of the turn is small and the control torque for the outside of the turn is small. The steering control torque is corrected so as to increase. That is, when the vehicle is traveling on a curve with a cant, the lateral G deviation ΔGy becomes negative. At this time, the vehicle is deviated to the outside of the turn with respect to the road center line LC, and the lateral position of the vehicle is changed to the inside of the turn. Is adjusted, the cant correction coefficient Kc is set to a value smaller than 1 according to the magnitude of the lateral G deviation ΔGy as shown by the characteristic C1. As a result, the steering control torque Tc multiplied by the cant correction coefficient Kc is reduced and corrected.

When the vehicle is running on a curve with a cant and is deviated to the inside of the turn with respect to the road center line LC and the lateral position of the vehicle is to be adjusted to the outside of the turn, the cant correction is performed. The coefficient Kc is set to a value larger than 1 according to the magnitude of the lateral G deviation ΔGy as shown by the characteristic C1. As a result, the steering control torque Tc multiplied by the cant correction coefficient Kc is corrected to increase.

Incidentally, since the lateral G deviation ΔGy includes not only the cant but also other steering influence factors applied to the vehicle, the control torque correction based on the lateral G deviation ΔGy, which is referred to as cant correction, is as follows. The correction is made for various steering influence factors acting on the vehicle. Although not shown in detail, the steering actuator 21 may be any actuator that can apply a torque to the steering shaft, and is configured by, for example, a small electric torque motor installed below the torsion bar of the steering shaft (on the power steering side). May be.

The output of the control torque calculation information is provided between the control torque calculation means 5 and the controller 6 so that the control torque actually exerted by the steering actuator 21 continues smoothly without abrupt change. A low-pass filter 25 for performing a smoothing process is provided. The lane departure prevention device as one embodiment of the present invention is configured as described above.
Is performed as shown in FIG.

That is, it is determined whether or not the control switch 23 is on (step S10). If the control switch 23 is not on, the lane departure prevention processing is not performed. If the control switch 23 is on, step S20 is performed. The following processing is performed. That is, first, the control torque is calculated by the control torque calculating means 5 according to the amount of lateral displacement (step S20), and the control torque is corrected by the control torque correcting means 5A (step S30). The steering actuator 21 is operated with a control amount corresponding to the corrected control torque, and a display signal is output to the operation display unit 24 (step S40).

The above processing will be described with reference to the block diagram of FIG. 10. The driver side performs a steering operation by appropriately judging the traveling lane while visually recognizing this. On the other hand, in the lane departure prevention device (lane guidance system), first, lane recognition for the traveling lane is performed by image recognition through the camera 2, and the amount of lateral deviation from the reference position of the vehicle lane (here, the road center line LC). ΔY is calculated, and the steering control torque Tc is calculated from the lateral shift amount ΔY. Further, the steering control torque Tc is cant corrected, and the steering actuator 21 is operated based on the corrected steering control torque Tc.

As a result, the steering torque of the driver and the control torque for steering by the steering actuator 21 are added and transmitted to the steered wheels 22 via the power steering device to steer the steered wheels 22. is there.
To describe these processes in more detail, in calculating the control torque, first, it is necessary to calculate the lateral deviation amount ΔY, which is an index of how much the vehicle deviates from the traveling lane. In this device, the traveling lane estimating means 4 estimates the relative position of the traveling lane (traveling lane) with respect to the own vehicle, and calculates the lateral deviation amount ΔY based on the estimated position. Here, the road center line L based on the image information from the camera 2
The lateral distance (road width direction, lateral direction of the camera image) between the center line of the vehicle and the road center line LC at the point (first detection point) closest to the vehicle in C is determined by the amount of lateral displacement (lateral deviation) Δ
Calculated as Y.

That is, in the present apparatus, white line recognition is performed for the white line 12L at the left end of the running lane and the white line 12R at the right end of the running lane. Position (in other words, the position of the vehicle with respect to the traveling lane) is estimated.
The recognition of R will be described with reference to the left white line 12L as an example.

First, as shown in FIG.
On a flat ground, the area in front of the vehicle (for example,
m), the monochrome image information is fetched for each minute control cycle, and a plurality of horizontal lines 11 are set at regular intervals on this screen for each cycle. Then, as shown in FIG.
On each horizontal line 11, a required range of the left and right positions of the white line position on the previous screen (for example, left and right 50 pixels [do
t]) is set as a white line search area (processing target area) 10. In the initial screen, a white line position on a straight road is used as previous screen data.

From the image information, as shown in FIG. 3C, the brightness of each horizontal line is differentiated in the horizontal direction from the left, and the differential data of each horizontal line is obtained as shown in FIG. 3D.
From the left], the peaks of the differential values appear in the order of plus and minus from the left, and the interval between the peaks is considered to be appropriate as the white line 12 (the interval from the plus peak to the minus peak is, for example, within 30 dots). ) Are extracted as white line candidates, and the midpoint thereof is stored as a white line candidate point 15 (see FIG. 3E).

Then, among these white line candidate points 15,
Only the point closest to the screen center is left as the final candidate point.
By limiting the white line candidate point 15 to the one closest to the center of the screen in this way, an object that causes noise (for example, the guardrail 14 or a vehicle in another traveling lane) exists outside the white line 12. Even in this case, the white line 12 can be reliably recognized from the image information obtained by the camera 2.

Finally, as shown in FIG. 3 (f), the continuity of the white line candidate points 15 in each horizontal line data in the vertical direction is sequentially verified from the bottom of the screen. First, the inclination between the upper and lower ends of the white line 12 on the previous screen is calculated in advance. If the lowermost point 15A is the white line 12, the candidate point 15B on the upper horizontal line 11 is calculated by the inclination ± 5 of the previous white line 12.
0 dot is compared, and candidate point 1
If 5B is within this range, it is regarded as a white line. If not, the candidate point 15B is rejected, and the coordinates calculated by interpolation from the above-mentioned inclination are regarded as the position of the white line.

By performing such an operation for each horizontal line, continuous white lines 12 can be recognized. Such white line recognition work is continuously performed at a required cycle, and the recognition of the white line 12 is updated each time.
In this manner, the white lines 12L, 1 on the left and right of the traveling lane are periodically repeated.
Recognition of 2R is performed in the same manner.

Then, the estimating means 4 calculates each road center line L
C _L, roads and averages the LC _R centerline LC (= LC _L + _L
C _R ) is calculated. Road center line LC estimated in this way
, The lateral shift amount (lateral deviation) ΔY and declination β and the curvature of the traveling lane (road curvature) are calculated.
The calculation of the steering control torque Tc by the control torque calculation means 5 is performed using a map, a table, or an arithmetic expression as shown in FIG. The steering control torque Tc is equal to the lateral shift amount ΔY.
And its size is limited by a constant value. That is, as shown in FIG. 5, if the vehicle deviates to the right from the road center line, a control torque Tc of left steering that guides the vehicle to the left side of the lane is set according to the lateral deviation amount ΔY, and the vehicle moves from the road center line. If the vehicle shifts to the left side, a control torque Tc for right steering that guides the vehicle to the right side of the lane is set according to the lateral shift amount ΔY. In any case, the magnitude of the control torque Tc is a constant value Tcm.
Limited by

By limiting the control torque Tc in this manner, the control torque Tc does not become a problem, and the magnitude of the control torque Tc is maintained to such an extent that the driver can easily overcome. Therefore, by applying the steering control torque Tc, the driver senses the lane departure (deviation from the road center line) and the correction direction from the feeling of steering of the steering wheel 20, and the correction of the vehicle position is performed by the driver. The steering operation is quickly performed. The steering control torque Tc itself is effective not only for warning the driver, but also for correcting the vehicle position. Further, the warning by the steering control torque Tc is also effective for a driver who looks aside, for example. In this case, the driver is encouraged to prevent the driver from looking aside while preventing a deviation from the lane.

Further, in the control torque calculation means 5, the control torque correction means 5A obtains the cant correction coefficient K with the characteristics C1 and C2 as shown in FIG.
Set c and perform cant correction. In other words, in general, when traveling on a curve with a cant, the gravity acting on the vehicle according to the cant works in a direction that helps turn,
The correction is performed such that the steering control torque toward the inside of the turn is reduced and the control torque for steering toward the outside of the turn is increased. As a result, a situation in which the steering control torque Tc increases or decreases due to the influence of the road cant and gives a feeling of strangeness to the driver is also solved.

Further, the steering control torque Tc is smoothed by the low-pass filter 25 and output, so that the steering control torque generated by the steering actuator 21 smoothly continues without sudden change. There is also an advantage that control for lane departure prevention can be stabilized. The calculation of the steering control torque Tc by the control torque calculation means 5 is not limited to the characteristic shown in FIG.

That is, the steering control torque Tc only needs to act so as to decrease the lateral shift amount ΔY as it increases. In particular, in a region where the lateral shift amount ΔY is small, the steering control torque Tc is set to 0. If the magnitude of the lateral deviation amount ΔY is larger than this region (dead zone), the steering control torque Tc may be set according to the lateral deviation amount ΔY. In this case, the steering control torque Tc may be linearly increased with respect to the lateral shift amount ΔY, or may be increased stepwise.

Further, as shown in FIG. 6, when the magnitude of the lateral deviation ΔY is larger than that of the dead zone, the lateral deviation Δ
Steering control torque T of a certain magnitude in the direction in which Y decreases
c may be set. Further, the calculation of the cant correction coefficient Kc by the control torque correction means 5A is not limited to the characteristic shown in FIG.

In other words, the cant correction coefficient Kc also needs to have such a tendency that the larger the cant degree (here, the lateral G deviation ΔGy), the more this effect is eliminated.
As shown in FIG. 8, the cant correction coefficient Kc is set to 1 in an area where the cant degree is small, and if the cant degree is larger than this area (dead zone), the cant correction coefficient Kc is set according to the cant degree. Is also good.

Further, in the present embodiment, the steering influence factor applied to the vehicle including the cant state is estimated as the lateral G deviation ΔGy by paying attention to the lateral acceleration generated in the vehicle. It is also possible to provide an information transmitting means for issuing cant information and an information receiving means for receiving the cant information on the vehicle side to obtain cant information by road-vehicle communication and to perform cant correction.

The transmission of information in this case may be by radio waves, but the cant information is included in the white line on the road side, and this information is obtained from the image information in the process of processing the image information captured by the camera 2 on the vehicle 1 side. The cant information may be extracted and the cant correction may be performed based on the obtained cant information. Furthermore, when a magnetic nail is provided on the road side, cant information is included in the magnetic nail, and the cant information is extracted from the magnetic information in the process of processing the magnetic information captured by the magnetic sensor on the vehicle side, and the cant is extracted. Correction may be performed.

Further, road position information including information on the distance between roads and the vehicle is stored in advance in the storage means, and the position information of the vehicle is detected by GPS or autonomous navigation. And the stored road position information, the cant information of the driving lane may be obtained.

[0065]

As described above in detail, according to the lane departure prevention device of the present invention, when the host vehicle is about to deviate from the traveling lane, the driver's steering force is set so as to prevent the deviation. Separately, a steering control torque that the driver can easily overcome is given by the steering actuator, so that the steering operation by the driver's intention is not hindered,
It is possible to provide guidance for preventing lane departure by applying steering control torque, and since the steering control torque is set to a magnitude corresponding to the amount of lateral displacement of the vehicle and the cant situation of the road surface, the vehicle tries to deviate An appropriate amount of steering control torque can be applied in accordance with the degree of driving and in consideration of the cant on the road surface, so that guidance for lane departure prevention can be accurately performed according to the situation. Further, according to the lane departure prevention device of the present invention, when the vehicle is about to deviate from the traveling lane, the driver can easily overcome the steering force separately from the driver's steering force in a direction to prevent the deviation. Since the control torque is applied by the steering actuator, it is possible to provide guidance to prevent lane departure by applying the control torque for steering without hindering the steering operation by the driver's intention. The size is set according to the deviation between the amount and the theoretical lateral acceleration and the actual lateral acceleration.Therefore, an appropriate size is set according to the degree to which the vehicle is going to deviate and considering the lateral force situation received from the road surface. As a result, the steering control torque can be given, and guidance for lane departure prevention can be accurately performed according to the situation.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of a lane departure prevention device as one embodiment of the present invention.

FIG. 2 is a diagram illustrating image processing for driving lane recognition according to an embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating traveling lane recognition according to an embodiment of the present invention in the order of (a) to (f).

FIG. 4 is a schematic plan view illustrating travel lane recognition.

FIG. 5 is a diagram showing an example of a setting map of a steering control torque according to the lane departure prevention device as one embodiment of the present invention.

FIG. 6 is a diagram showing another example of a setting map of the steering control torque according to the lane departure prevention device as one embodiment of the present invention.

FIG. 7 is a diagram showing an example of a cant correction map of the steering control torque according to the lane departure prevention device as one embodiment of the present invention.

FIG. 8 is a diagram showing another example of a cant correction map of the steering control torque according to the lane departure prevention device as one embodiment of the present invention.

FIG. 9 is a flowchart illustrating the operation of the lane departure prevention device as one embodiment of the present invention.

FIG. 10 is a block diagram illustrating the operation of the lane departure prevention device as one embodiment of the present invention.

[Description of Signs] 1 vehicle 2 camera 3 image information processing means 4 traveling lane estimating means 4A lateral displacement amount calculating means 5 control torque calculating means 5A control torque correcting means 6 control means (controller) 7 cant information detecting means 20 steering wheel (handle) 21) Steering actuator 22 Steering wheel 23 Switch 24 Operation display part 25 Low-pass filter 31 Lateral acceleration sensor (lateral G sensor) 32 Vehicle speed sensor 33 Steering angle sensor LC Road center line

Claims (2)

[Claims] When the vehicle deviates from the traveling lane, a steering control torque that the driver can easily overcome is provided by the steering actuator of the vehicle separately from the steering torque applied by the driver in a direction to prevent the deviation. A lane departure prevention device that guides prevention of lane departure of the vehicle by calculating a lateral deviation amount of a traveling position of the vehicle from a reference position of the traveling lane; and a lateral deviation amount calculating unit. Control torque calculating means for calculating a control torque based on the calculated lateral shift amount; and controlling the steering actuator such that the control torque calculated by the control torque calculating means is generated in a direction to reduce the lateral shift amount. Control means; and cant information detecting means for detecting cant information on the road surface of the traveling lane. The control torque had wherein the control torque correcting means for correcting, based on the detected Kant information the cant information detecting means is provided, the lane departure prevention apparatus. 2. A steering control torque of such a degree that the driver can easily overcome the steering torque applied by the driver in a direction to prevent the vehicle from deviating from the traveling lane in a direction for preventing the deviation from the traveling lane. A lane departure prevention device that guides prevention of lane departure of the vehicle by calculating a lateral deviation amount of a traveling position of the vehicle from a reference position of the traveling lane; and a lateral deviation amount calculating unit. Control torque calculating means for calculating a control torque based on the calculated lateral shift amount; and controlling the steering actuator such that the control torque calculated by the control torque calculating means is generated in a direction to reduce the lateral shift amount. Control means for detecting an actual lateral acceleration occurring in the vehicle, and steering for detecting a steering angle of the vehicle. Detection means; vehicle speed detection means for detecting the vehicle speed of the vehicle; theory for calculating a theoretical lateral acceleration generated in the vehicle based on the steering angle detection means and the steering angle and the vehicle speed detected by the vehicle speed detection means Lateral acceleration calculating means; and deviation calculating means for calculating a deviation between a theoretical lateral acceleration calculated by the theoretical lateral acceleration calculating means and an actual lateral acceleration detected by the actual lateral acceleration detecting means. A lane departure prevention device, characterized in that the control torque calculating means is provided with control torque correcting means for correcting the control torque based on the lateral deviation amount based on the deviation calculated by the deviation calculating means.