JP3201323B2 - Lane departure prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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
No. -10850) 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]

The lane departure prevention apparatus captures a road image ahead of the vehicle through image information input means such as a camera, and estimates a traveling lane based on a road white line on the road image. Generally, a steering control or a warning is issued so that the vehicle does not deviate from the estimated lane. This is because normal road surfaces have low brightness,
This is because, while the change in luminance is small, the luminance of the white line is much higher than that of a normal road surface, so that the white line can be easily recognized by focusing on the brightness difference of the road.

However, depending on the road conditions, for example, when the road surface is wet or when there are many puddles, the light is easily reflected, so that the luminance of the road surface becomes high, and the luminance difference between the road surface and the white line is small. turn into. In such a case, it becomes difficult to discriminate the white line from the normal road surface, and the recognition accuracy of the white line may be reduced, so that accurate lane departure prevention may not be performed.

As a countermeasure for such a case, Japanese Patent Application Laid-Open No. 7-17299 discloses a technique for promptly stopping the lane departure prevention control when the white line recognition accuracy cannot be sufficiently ensured. . However, in the case where the white line recognition malfunctions once and recovers immediately, such as when the white line is broken intermittently on the way, the control is interrupted each time and the control becomes discontinuous. Therefore, the driver feels strange.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a lane departure prevention device capable of maintaining continuity of control even when white line recognition fails due to road conditions. And

[0010]

Therefore, in the lane departure prevention apparatus according to the first aspect of the present invention, the white line recognizing means uses the road image information in front of the vehicle input by the image information input means on the road. The running lane is recognized by the running lane estimating means based on the recognized white line.

The lateral displacement calculating means calculates the lateral displacement of the traveling position of the vehicle from the reference position of the traveling lane estimated by the traveling lane estimating means, and the lateral acceleration computing means calculates the lateral deviation of the vehicle from the road curvature of the traveling lane. Is calculated. The control torque calculating means calculates a lateral displacement amount corresponding control torque based on the lateral displacement amount calculated by the lateral displacement amount calculating means and calculates a lateral acceleration corresponding control torque based on the lateral acceleration calculated by the lateral acceleration calculating means, The control torque for steering is calculated from the calculated control torque corresponding to the lateral deviation amount and the control torque corresponding to the lateral acceleration. The control means controls the steering actuator such that the calculated steering control torque is generated in a direction that prevents the vehicle from departing from the traveling lane.

On the other hand, when white line recognition by the white line recognition unit is not normal, the accuracy of the lateral acceleration calculated by the lateral acceleration calculation unit based on the white line becomes unstable. The control torque calculating means calculates a lateral acceleration corresponding control torque based on the actual lateral acceleration detected by the lateral acceleration detecting means instead of the lateral acceleration calculated by the lateral acceleration calculating means. To do.

Thus, even when the white line recognition is malfunctioning, the continuity of the control is maintained, and the driver does not feel uncomfortable. Further, in the lane departure prevention device according to the present invention, when the white line recognition by the white line recognition unit becomes abnormal, the control torque calculation unit sets the control torque corresponding to the lateral deviation amount based on the lateral deviation amount calculated by the lateral deviation amount calculation unit. Is gradually reduced.

As a result, it is possible to prevent application of an inappropriate control torque corresponding to the lateral deviation amount based on unreliable white line information, and to prevent a sudden stop of the control without giving the driver an uncomfortable feeling. Further, in the lane departure prevention device according to the third aspect of the present invention, if the malfunction of white line recognition by the white line recognition means continues for a predetermined time or more, the control torque calculation means sets the actual lateral acceleration detected by the lateral acceleration detection means to The control gain of the control torque corresponding to the lateral acceleration is gradually reduced.

Thus, in the case of a sporadic white line recognition malfunction, the control continuity is maintained by the control torque corresponding to the lateral acceleration based on the actual lateral acceleration. It is possible to prevent an inappropriate lateral acceleration-based control torque based on the actual lateral acceleration with low reliability from being applied for a long period of time, so that the control is not suddenly stopped and the driver does not feel uncomfortable.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 12 show a lane departure prevention device as an embodiment of the present invention.
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 in the vehicle as shown in FIG. 2 (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 vehicle with respect to the traveling lane, a camera (image information input means) 2 as an image pickup means for picking up an image of a road state in front of the vehicle 1 and image information from the camera 2 are appropriately transmitted. Image information processing means (white line recognition means) 3 for processing and recognizing left and right white line positions on the road ahead;
A lateral shift amount calculating unit 4A for predicting and calculating a lateral shift amount ΔY after a predetermined time t with respect to a reference position of the traveling lane (traveling lane) of the vehicle from the white line position image information by the image information processing unit 3; A lateral acceleration calculating means 7 for calculating the acceleration G is provided.

Note that the lateral deviation amount ΔY corresponds to a determination parameter relating to the degree that the vehicle 1 is likely to deviate from the lane, and the lateral acceleration G corresponds to a determination parameter relating to the driver's burden on a curved road. Also, the lateral displacement amount calculating means 4A
Is a traveling lane estimating means (traveling lane estimating means) 4 for estimating a relative position of a traveling lane (traveling lane) with respect to the own vehicle together with a road curvature calculating means 4B for computing a road curvature ρ which is a determination parameter of the lateral acceleration G. It is provided as a functional element.

Further, the present lane departure prevention apparatus uses the lateral deviation amount (lateral deviation) Δ calculated by the lateral deviation amount calculating means 4A.
Y, that is, a control torque calculating unit that calculates the steering control torque Tc based on the degree of departure from the lane and the lateral acceleration G calculated by the lateral acceleration calculating unit 7, that is, the burden on the driver on a curved road. 5, 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 the steering control torque Tc calculated by the control torque calculation means 5 reduces the lateral shift amount ΔY; , A control means (controller) 6 for controlling the steering actuator 21 so as to be generated in a direction opposing the lateral acceleration G.

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, road curvature calculating means 4)
B), the lateral acceleration calculation means 7, the control torque calculation means 5, and the controller 6 are a CPU, an input / output interface, an RO
It is configured as an electronic control unit including M, RAM, and the like. First, the position of the vehicle in relation to the driving lane
That is, the calculation of the lateral displacement amount ΔY of the vehicle will be described.

First, as shown in FIG. 3, the image information processing means 3 fetches an original image 3A from the camera 2, extracts a road white line from the original image 3A, and converts the extracted road white line image into a vertical image. The image is converted into a two-dimensional image 3B as viewed from above. Next, the recognition of the white lines 12L and 12R will be described with reference to 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. 4B, 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. 4C, 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. 4E, 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. 4F, 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 (within the error range). .

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. By the way, even when the candidate point 15 which does not fall within the error range exists as described above, the white line 12 can be recognized by performing the interpolation calculation from the inclination between the upper and lower ends of the white line 12 in the previous screen. However, if many of the candidate points 15 on the screen are rejected because they do not fall within the error range, it cannot be said that the white line on the road surface can be recognized effectively. Can not expect precise control. Therefore, in the image information processing means 3, the candidate points 15
Is rejected, the recognition loss signal is output to the control torque calculation means 5 assuming that the white line recognition is malfunctioning. However, if either one of the left and right white lines 12L and 12R is effectively recognized, control can be performed based on the effectively recognized white line 12, and no recognition lost signal is output.

The case where the white line 12 cannot be recognized as described above includes a case where the road surface is wet and a case where a large number of puddles are present. In such a case, since the light is easily reflected, the luminance of the road surface increases, and the luminance difference between the white line 12 and the white line 12 becomes small. Therefore, it is difficult to distinguish the white line 12 from the normal road surface. Further, even when the white line 12 is broken or unclear on the way, or when there is a display or an object close to white in the vicinity of the white line 12, the white line may not be recognized.

In the traveling lane estimating means 4, the white lines 12R, 12R on the original image 3A recognized in each recognition cycle are
The L is converted into a plan view image 3B, on the basis of the road centerline LC _R which may be estimated from the travel 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, the center line of the road The LC is estimated. Then, based on the road center line LC, the lateral displacement amount ΔY ₀ and the deflection angle β at the present time are calculated by the lateral displacement amount calculating means 4A.

The declination β is the angle between the tangent direction of the curved road center line LC and the traveling direction of the vehicle, as shown in FIG. The tangent direction of the road center line LC is from the road center line position (reference line position) at the first detection point (shown as perigee in the figure) which is the detection level closest to the vehicle in the image information obtained from the camera image. This is a direction toward a road center line position (reference line position) at a second detection point (shown as an apogee in the figure) further away from the vehicle 1 by a predetermined distance L than this perigee, and is calculated from each position information. be able to. Further, the vehicle traveling direction is a direction toward the vehicle position at a point in time when the vehicle is separated from the current vehicle position by a predetermined distance L while maintaining the current steering angle, and can be calculated from the information of these two points.

In this example, the center line of the host vehicle at the first detection point closest to the vehicle (see point P1).
The lateral distance between the road and the road center line LC (see the point LC1) (the distance in the road width direction, that is, the lateral direction of the camera image) is calculated as the current lateral displacement amount (current lateral deviation) ΔY ₀ . The second detection point is a point (L) that can be predicted to reach a predetermined time t after the first detection point (for example, 1.0 second).
C2, P2), that is, points separated by a distance L (= Vt) obtained by multiplying the current vehicle speed V by the predetermined time t from the first detection point, and these first detection points (LC1)
The angle formed between the straight line connecting the second detection point (LC2) and the traveling direction line (P1P2) of the vehicle 1 is calculated as the argument β. The vehicle position (P2) that can be predicted to arrive after the predetermined time t is determined by the steering angle α detected by the steering angle sensor 27.
Is calculated based on

The lateral deviation amount calculating means 4A multiplies the declination angle β calculated as described above by the vehicle speed V of the vehicle detected by the vehicle speed sensor 32 and a predetermined time t, and calculates the lateral deviation change amount Δy ( [Delta] y = calculates β × V × t), the predicted lateral deviation by adding the lateral deviation (lateral deviation) [Delta] Y ₀ at the present time to (hereinafter, referred to simply as the lateral shift amount) [Delta] Y (= [Delta] Y
₀ + β × V × t). The predetermined time t is set to an appropriate time in consideration of the driver's general operation speed of the steering wheel 20 and the speed of recognition of road conditions by the image information processing means 3 and the like. Further, it may be variable according to the vehicle speed V, and the predetermined time t may be set so that the distance L from the first detection point to the second detection point is constant.

On the other hand, the road curvature calculating means 4B estimates the curvature (road curvature) ρ of the traveling lane based on the image information of the road center line. First, as shown in FIG. 6, for example, the above-described first detection point (LC1) and second detection point (LC2) are further changed to a second detection point (LC2).
Is given a third detection point (LC3) forward by a distance L from
A first vector LC1LC2 from the first detection point (LC1) to the second detection point (LC2), and a second detection point (LC2)
Vector LC2 from the second detection point (LC3) to the third detection point (LC3)
The angle θ formed with LC3 is calculated as a curvature index (curvature characteristic) at the second detection point (LC2).

Then, the curvature (road curvature) ρ of the traveling lane is calculated from the distance L and the curvature index θ by the following equation. ρ = 2 sin (θ / 2) / L (1) That is, the value of the curvature index θ is the second detection point (LC2)
Is an index representing the degree of curvature of the curve at
Is larger, the curvature ρ of the curve at the second detection point (LC2) is larger, indicating that the curve is steeper.

The lateral acceleration calculating means 7 calculates the lateral acceleration G acting on the vehicle based on the curvature ρ of the traveling lane calculated by the road curvature calculating means 4B in this way. That is, assuming that the magnitude of the traveling speed of the vehicle detected by the vehicle speed sensor 32 is V, the lateral acceleration G is calculated by the following equation. G = ρ × V ² (2) The vehicle 1 is provided with a lateral acceleration sensor 31.
It is possible to detect the lateral acceleration acting on the vehicle.

The control torque calculating means 5 performs steering based on the lateral displacement ΔY of the vehicle with respect to the reference position (the center position of the road width) of the traveling lane thus calculated and the lateral acceleration G acting on the vehicle 1. The control torque Tc is set. That is, as shown in FIG.
A function for calculating a side slip prevention torque (a side shift amount control steering torque) Ty corresponding to the side shift amount ΔY (side slip amount control steering torque calculation unit) 5A, and a calculation unit 5A
To the lateral displacement prevention torque Ty due to the above, a steering assist torque (control torque for lateral acceleration corresponding steering) Tg corresponding to the lateral acceleration G
Function of adding and correcting 1 (steering control torque correcting means) 5
B is provided.

The steering assist torque T corresponding to the lateral acceleration G
In the correction by g1, when a lateral acceleration G is applied to the vehicle, a steering force opposing the lateral acceleration G is required. By assisting such a steering force, steering control for preventing lane departure is performed. This is to make it possible to perform on a curved road or the like without discomfort. That is, in addition to the lateral deviation prevention control using the lateral deviation prevention torque Ty corresponding to the lateral deviation amount ΔY, the lateral acceleration G
The steering control is also performed by the steering assist torque Tg <b> 1 corresponding to.

Generally, when the vehicle is traveling on a curved road, the centrifugal force acting in the lateral direction of the vehicle acts in the direction that hinders turning according to the curvature of the curve and the traveling speed of the vehicle. The acceleration is calculated by the lateral acceleration calculating means 7, and the steering assist torque Tg1 is added according to the magnitude of the calculated lateral acceleration G to correct the steering control torque.

Here, the lateral displacement prevention torque Ty will be described. The lateral displacement prevention steering control torque calculating means 5A sets the lateral displacement prevention torque Ty in proportion to the lateral displacement amount ΔY as shown in FIG. In FIG. 7, 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. Downward steering indicates left steering, and downward steering indicates right steering, which guides the vehicle to the right side of the lane.

That is, as shown in FIG. 7, if the vehicle shifts from the road center line to the right side, a left-side steering prevention torque Ty for guiding the vehicle to the left side of the lane is set in accordance with the amount of side shift ΔY. If the vehicle deviates to the left from the road center line, a lateral deviation prevention torque Ty for right steering that guides the vehicle to the right side of the lane is set according to the lateral deviation amount ΔY. However, in each case, the magnitude of the lateral displacement prevention torque Ty is limited by a constant value Tym. Here, when the magnitude of the lateral deviation amount ΔY becomes Y1, the magnitude of the lateral deviation prevention torque Ty is limited to a constant value Tym. This is because the side slip prevention torque Ty is different from the steering torque used for automatic steering, and its main purpose is to warn the driver. Since the vehicle position is corrected by the driver's steering operation, the steering control torque is used. Tc is limited to a size that does not hinder the driver's steering operation, that is, a size that the driver can easily overcome.

The steering control torque correcting means 5B sets the steering assist torque Tg1 in proportion to the lateral acceleration G as shown in FIG. In FIG. 9, the abscissa regarding the lateral acceleration G indicates that the right direction indicates the effect of the lateral acceleration of the vehicle to the right and the left direction indicates the effect of the lateral acceleration of the vehicle to the left. The ordinate relating to the torque Tg1 indicates left steering in which the upward direction guides the vehicle to the left side of the lane, and rightward steering in which the downward direction guides the vehicle to the right side of the lane.

As shown in FIG. 9, if lateral acceleration acts on the vehicle in the right direction, a left-hand steering assist torque Tg1 for guiding the vehicle to the left side of the lane is set in accordance with the lateral acceleration G, and the vehicle is subjected to the lateral acceleration G. If lateral acceleration to the left acts, this lateral acceleration G
The steering assist assist torque Tg1 for right steering that guides the vehicle to the right side of the lane is set according to. However, in any case, the magnitude of the steering assist torque Tg1 is limited to a constant value Tgm. Here, when the magnitude of the lateral acceleration G becomes G1, the magnitude of the steering assist torque Tg1 is limited to a constant value Tgm. This limits the driver to a size that can be easily overcome, as described above.

In this manner, the lateral displacement ΔY and the lateral acceleration G
, Which are respectively set based on
The steering-holding assist torque Tg1 is multiplied by appropriate control gains Ky and Kg by a control torque calculating unit 5D provided in the control torque calculating means 5, and then the multiplied value Kg is calculated.
The sum of y · Ty and Kg · Tg1 is output to the controller 6 as the steering control torque Tc.

When the white line recognition by the image information processing means 3 is not normal, a recognition lost signal is input from the image information processing means 3 to the control torque calculating means 5, and while the recognition lost signal is being input. Is calculated based on the information of the road center line LC with low accuracy, both the lateral slippage prevention torque Ty and the steering assist torque Tg1 can be effectively output as the steering control torque Tc to the controller 6 without any change. There is a high possibility that the function will not be exhibited.

When the recognition loss signal is input from the image information processing means 3, the control torque calculating section 5D firstly switches the switching means 5 which is a functional element of the control torque calculating section 5D.
With d, the setting of the steering assist torque based on the lateral acceleration G calculated by the lateral acceleration calculating means 7 by the steering control torque correcting means 5B actually acts on the vehicle 1 by the substitute steering control torque correcting means 5C. The setting is switched to the setting of the steering assist torque based on the lateral acceleration (actual lateral acceleration) G '. Then, the steering assist torque Tg2 set by the substitute steering control torque correcting means 5C is multiplied by the gain Kg, and the multiplied value Kg · Tg2 is used as the lateral displacement prevention torque Ty.
To obtain a steering control torque Tc.

Incidentally, the actual lateral acceleration G 'is detected by a lateral G sensor (lateral acceleration detecting means) 31 provided in the vehicle 1, and the substitute steering control torque correcting means 5C outputs the actual lateral acceleration G'. Based on the acceleration G ', the steering assist torque Tg2 is set from a map as shown in FIG. 9, similarly to the steering control torque correcting means 5B. Further, due to an error between the lateral acceleration G calculated by the lateral acceleration calculating means 7 and the actual lateral acceleration G ', a sudden torque change may occur when switching from the steering assist torque Tg1 to the steering assist torque Tg2. However, as shown in FIG. 2, this is dealt with by performing a smoothing process by a low-pass filter 25 interposed between the control torque calculating means 5 and the controller 6.

As described above, with regard to the steering control using the steering assist torque Tg1, it is possible to substitute the steering assist torque Tg2 based on the actual lateral acceleration G 'when the white line recognition is malfunctioning. Regarding the lateral displacement prevention control based on Ty, the lateral displacement amount ΔY, which is the reference for calculating the lateral displacement prevention torque Ty, can be obtained only by the image information from the camera 2, and therefore cannot be substituted by other means. In addition, when the white line recognition is malfunctioning, even if the side slip prevention torque Ty is applied as it is, there is a large possibility that the function of preventing the lane departure will not be effectively exerted. is there.

Therefore, the control for preventing the lateral displacement by the lateral displacement preventing torque Ty is stopped when the recognition lost signal is inputted in order to prevent inappropriate torque from being applied. However, if the application of the lateral deviation prevention torque Ty is suddenly stopped or the white line recognition becomes normal and the lateral deviation prevention torque Ty is suddenly applied again, the driver will feel uncomfortable, so instead of suddenly stopping application, When the recognition lost signal is input, the gain Ky is gradually reduced to stop over several seconds.

In this way, when the gain Ky becomes 0 and the application of the lateral displacement prevention torque Ty is stopped, only the steering assist torque Tg2 based on the actual lateral acceleration G 'is changed to the steering control torque Tg.
However, since the actual lateral acceleration G ′ is generated not only by a curved road but also by other factors such as a meandering operation of the vehicle, accurate steering control is not necessarily performed by the steering assist torque Tg2. Cannot be performed, and the driver may feel uncomfortable due to unnecessary torque application. That is, the steering assist torque Tg2 based on the actual lateral acceleration G 'is used when the white line recognition is intermittently malfunctioning and the lateral acceleration calculating means 7 cannot calculate the lateral acceleration G accurately. Is effective for temporarily substituting until normal recovery, but not suitable for permanent use.

Therefore, when the recognition lost signal continues for a predetermined time, it is determined that there is no single white line recognition malfunction.
As in the lateral displacement prevention control, the gain Kg is gradually reduced, and stops over several seconds. As described above, when the recognition lost signal continues for a predetermined time or longer, the gains Ky and Kg are both set to 0, and the lane departure prevention control by applying the steering control torque Tc is stopped, but the white line recognition is restored. In this case, the lane departure prevention control by the application of the steering control torque Tc is resumed.

At this time, the switching means 5d switches to the steering control torque correcting means 5B side, and the steering assist torque Tg1 is set based on the lateral acceleration G calculated by the lateral acceleration calculating means 7, and suddenly, In order to prevent the driver from feeling uncomfortable due to the application of the torque, the gains Ky and Kg are gradually increased as in the case of the stop. Similarly, when the white line recognition is recovered while the gain Ky or the gain Kg is gradually decreasing, the white line recognition is gradually increased therefrom to prevent the driver from feeling uncomfortable due to sudden torque fluctuation.

For example, (a), (b), and (c) of FIG.
Is a time chart showing the input of the recognition lost signal and the corresponding time change of the gain Ky and the gain Kg, respectively.
It shows switching between g1 and Tg2. The function of the control torque calculating means 5 will be described more specifically with reference to FIG.

The following explanation is based on the assumption that the control torque calculating means 5 does not provide any gain other than the gains Ky and Kg with respect to the setting of the control torque, or that any gain is provided even if it is provided. Assume that it is 1. As shown in FIGS. 11A, 11B and 11C, when the recognition lost signal is OFF, the gains Ky and Kg are both set to 1.0. The switching means 5d is set on the steering control torque correcting means 5B side, and the steering control is performed by the steering assist torque Tg1 based on the lateral acceleration G calculated by the lateral acceleration calculating means 4B. Therefore, in this case, the steering control torque Tc (Tc = Ty + Tg1) is applied from the steering actuator 21.

However, the recognition lost signal is input (ON).
When this is done (time t ₁ ), the switching means 5d switches to the substitute steering control torque correction means 5C, and the steering is maintained by the substitute steering assist torque Tg2 based on the actual lateral acceleration G ′ detected by the lateral G sensor 31. When the control is switched, the gain Ky of the lateral displacement prevention torque Ty also gradually decreases at the constant speed dKy1. That is, the steering control torque Tc is T
c = Ky · Ty + Tg2. After a few seconds (time t
_{In 12} ), the gain Ky becomes 0 (time point t ₂ ), the lateral slip prevention control by the lateral slip prevention torque Ty is stopped, and only the steering control by the substitute steering auxiliary torque Tg2 is performed.

When the malfunction of the white line recognition continues for a certain time (time t ₁₃ ), the gain Kg is gradually decreased at a certain speed dKg 1 (time t ₃ ), and several seconds later (time t ₃₄ ).
Then, the gain Kg is also set to 0 (time point t ₄ ), and the steering control by the substitute steering assist torque Tg2 is also stopped. On the other hand, when the white line recognition is recovered and the recognition lost signal is turned off (time t)
₅ ), both sideslip prevention control and steering hold control are restarted, and both gains Ky and Kg are constant speeds dKy2 and dKg2, respectively.
To increase. Incidentally, when the recognition lost signal becomes OFF (time t _5), the switching means 5d is switched to steering control torque compensator 5B side, lateral acceleration calculating means 7
Steering assist torque Tg based on lateral acceleration G calculated in
1 has been switched to the steering control. Therefore, with the recovery of the white line recognition, the steering control torque Tc (Tc = Ky · Ty + Kg · Tg) is output from the steering actuator 21.
1) is given.

Eventually, both the gains Ky and Kg
1.0 (each time t₆, T ₇), Steering actuation
The normal steering control torque Tc (Tc
= Ty + Tg1). Note that here the gain
Explanation when the normal setting of Ky and Kg is set to 1.0
However, it is of course possible to set other appropriate values.
Yes, and may be variable in accordance with driving conditions and the like.
Further, the decreasing speeds dKy1, dKg of the gains Ky, Kg
1, the increase speed dKy2, dKg2 are set separately.
Or the same setting, and the gains Ky and Kg
The time of decrease and rise from the maximum value to 0 is constant (for example, 5
Second).

The steering actuator 21 may be any actuator that can apply a torque to the steering shaft. For example, as shown in FIG. 12, the steering actuator 21 is installed below the torsion bar (not shown) of the steering shaft 40 (on the power steering side). It may be constituted by the small electric torque motor 41 described above. In this case, the motor 4
1 is transmitted to the steering shaft 40 via a worm gear 42 including a worm 42a and a worm wheel 42b.
A torque limiter 43 is interposed between b and the steering shaft 40. The torque limiter 40 allows the driver to easily operate the handle 20 even if the motor 41 is stuck. Further, the maximum torque of the motor 41 is set to a necessary minimum, so that even if a failure occurs in the controller 6, excessive control torque is not transmitted to the driver.

The output of the control torque calculation signal 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. Since the lane departure prevention device as one embodiment of the present invention is configured as described above, when the control switch 23 is turned on, the lane departure prevention process starts.

First, in the lane departure prevention apparatus (lane guidance system), the image information processing means 3 appropriately processes image information in front of the vehicle input from the camera 2 to recognize left and right white line positions on the road ahead. Then, based on the white line position image information, the traveling lane estimating means 4 estimates the relative position of the traveling lane with respect to the own vehicle. Then, the lateral shift amount calculating means 4A predicts the lateral shift amount ΔY of the own vehicle with respect to the traveling lane after a predetermined time, and the lateral acceleration calculating means 7 calculates the lateral acceleration G acting on the vehicle. The control torque calculating means 5 calculates a steering control torque Tc for preventing lane departure based on the lateral deviation amount ΔY and the lateral acceleration G.

Here, the calculation of the steering control torque Tc will be described in detail. 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 after a predetermined time. In the present apparatus, the lateral displacement amount ΔY ₀ at the present time is calculated by the lateral displacement amount calculating means 4A based on the relative position of the traveling lane with respect to the own vehicle estimated by the traveling lane estimating means 4. Here, based on the image information from the camera 2, the lateral distance between the vehicle center line and the road center line LC at the point (first detection point) closest to the vehicle (road width direction, lateral distance of the camera image) Is calculated as a lateral shift amount (lateral deviation) ΔY ₀ .

When the current lateral shift amount ΔY ₀ is calculated, the reference line position information at the first detection point separated from the vehicle by a predetermined distance and the distance L further from the vehicle 1 than this perigee are calculated. The tangential direction of the curved road center line LC is calculated from the reference line position information at the second detection point. Further, the vehicle traveling direction is calculated from the current vehicle position information and the vehicle position information at the time when the vehicle is separated by the distance L while maintaining the current steering angle, and the vehicle traveling direction and the tangential direction of the road center line LC are calculated. The deviation angle β to be formed is calculated.

Here, as shown in FIG. 5, the second detection point (LC2) can be predicted to reach the first detection point (LC1) after a predetermined time t, that is, the first detection point (L
These first detection points (L) are located at a distance L obtained by multiplying the current vehicle speed V by a predetermined time t from C1).
The angle between a straight line connecting C1) and the second detection point (LC2) and the traveling direction line of the vehicle 1 is calculated as the declination β.

As described above, the current lateral shift amount ΔY
_{When 0} and the declination β are calculated, the lateral shift amount calculating means 4A
Further, the deviation angle β is multiplied by the vehicle speed V of the vehicle detected by the vehicle speed sensor 32 and a predetermined time t to obtain a lateral shift change amount Δy (Δy = β
× V × t), and the current lateral displacement (lateral deviation) ΔY ₀ is added to this to calculate a predicted lateral displacement ΔY (= ΔY ₀ + β × V × t) after a predetermined time t.

On the other hand, the lateral acceleration G, which is an index of the magnitude of the centrifugal force acting to prevent the vehicle from turning on a curved road, is calculated by the lateral acceleration calculating means 7.
The curvature (road curvature) ρ of the travel lane is estimated by the road curvature calculation means 4B, which is a functional element of the travel lane estimation means 4, based on the image information of the road center line LC, and the lateral acceleration G is calculated based on the road curvature ρ. calculate.

That is, as shown in FIG. 6, a first detection point (LC1) and a second detection point (L
With respect to C2), a third detection point (LC3) is further taken forward by a distance L from the second detection point (LC2), and a first detection point (LC1) from the first detection point (LC1) to the second detection point (LC2). The angle θ between the vector LC1LC2 and the second vector LC2LC3 from the second detection point (LC2) to the third detection point (LC3) is calculated as a curvature index (curvature characteristic) at the second detection point (LC2). And these distances L
The curvature (road curvature) ρ of the traveling lane at the second detection point (LC2) is calculated from Equation (1) using the equation (1), and the traveling speed V of the vehicle detected by the vehicle speed sensor 32 is used. Then, the lateral acceleration G is calculated from the equation (2).

When the lateral displacement ΔY and the lateral acceleration G are calculated in this way, the control torque calculating means 5 first
FIG. 7 shows the control torque calculating means 5A for the lateral displacement corresponding steering.
The lateral displacement prevention torque Ty is calculated using a map, a table, or an arithmetic expression as shown in FIG. Side slip prevention torque Ty
Is proportional to the lateral shift amount ΔY, and its magnitude is limited by a constant value. That is, as shown in FIG. 7, when the vehicle shifts to the right from the road center line, a left-side steering prevention torque Ty for guiding the vehicle to the left side of the lane is set according to the side shift amount ΔY. If the vehicle is deviated to the left, the lateral deviation prevention torque Ty for right steering that guides the vehicle to the right side of the lane is set according to the lateral deviation amount ΔY, but in any case, the magnitude of the lateral deviation prevention torque Ty is limited by a constant value Tym. .

By limiting the side slip prevention torque Ty in this manner, the side slip prevention torque Ty does not become excessive, and the magnitude of the side slip prevention torque Ty is maintained to such an extent that the driver can easily overcome. When the side slip prevention torque Ty is applied, the driver senses the lane departure (deviation from the road center line) and the correction direction from the feeling of holding the steering wheel 20 or the like, and the correction of the vehicle position is promptly performed by the driver's steering operation. Will be performed. The side slip prevention torque Ty itself is effective not only for warning the driver, but also for correcting the vehicle position. Further, the warning by the side slip prevention torque Ty is also effective for, for example, a driver of inattentive driving. In this case, the driver is encouraged to prevent inattentive driving while preventing a deviation from the lane.

The side slip prevention torque Ty is calculated not only by the current side slip amount ΔY ₀ but also by the side slip change amount Δy after a predetermined time t predicted from the vehicle speed V and the declination β at the current side slip amount ΔY _0. Since it is determined on the basis of the predicted lateral shift amount ΔY obtained by the addition, the degree of deviation of the vehicle can be estimated in advance, and control can be performed to prevent the vehicle from deviating so that control delay does not occur. Guidance for departure prevention can be given accurately according to the situation.

It should be noted that the control torque calculating means 5 for side-shift steering is provided.
The calculation of the lateral displacement prevention torque Ty based on A is performed by calculating the lateral displacement amount ΔY
However, the characteristics are not limited to those shown in FIG. That is, the lateral displacement prevention torque Ty may be any value that acts to reduce the lateral displacement amount ΔY as it increases. In particular, in a region where the lateral displacement amount ΔY is small, the lateral displacement prevention torque Ty is set to 0, and in this region (dead zone) If the magnitude of the lateral displacement amount ΔY is larger than the value of ()), the lateral displacement prevention torque Ty
May be set according to the lateral shift amount ΔY. In this case, the lateral deviation prevention torque Ty may be linearly increased with respect to the lateral deviation amount ΔY, or may be increased stepwise.

Further, as shown in FIG. 8, when the magnitude of the lateral deviation ΔY is larger than that of the dead zone, the lateral deviation Δ
A lateral displacement prevention torque T of a certain magnitude in the direction in which Y decreases
ym may be set. Next, the control torque calculating means 5 uses the steering control torque correcting means 5B to
The steering assist torque Tg1 is calculated using a map, a table, or an arithmetic expression as shown in FIG. That is, as shown in FIG. 9, when the traveling lane is curved to the left, the lateral acceleration G acting on the vehicle acts in the right direction that hinders the turning of the vehicle. A left steering steering assist torque Tg1 for turning the vehicle to the left is set. When the traveling lane is curved rightward, a right steering for turning the vehicle to the right according to the magnitude of the lateral acceleration G is set. The auxiliary torque Tg1 is set. However, in order to maintain the magnitude of the steering assist torque Tg1 to such an extent that the driver can easily overcome, when the magnitude of the lateral acceleration G is equal to or more than G1, the magnitude of the steering assist torque Tg1 is limited to a constant value Tgm.

When the steering assist torque Tg1 is applied, the driver can reduce the steering force of the steering wheel 20 on a curved road, and can easily perform the steering operation even when a large lateral acceleration G acts. Become. The steering assist torque Tg1 predicts in advance the lateral acceleration G that will act on the curve where the vehicle is about to enter, and is determined based on the predicted lateral acceleration G. The steering assist torque Tg1 can be added so as to encourage steering along the steering wheel. For this reason, the steering assist torque Tg1 also has the effect of alerting the driver that the vehicle is approaching a curve, and is effective, for example, for a driver looking aside.

The calculation of the steering assist torque Tg1 by the steering control torque correcting means 5B is not limited to the characteristic shown in FIG. In other words, the steering assist torque Tg1 also needs to have such a tendency that this effect is eliminated as the lateral acceleration G increases.
As shown in FIG. 0, the steering assist torque Tg1 is set to 0 in a region where the lateral acceleration G is small, and if the magnitude of the lateral acceleration G is larger than this region (dead zone), the steering assist torque Tg1 is set.
1 may be set according to the lateral acceleration G.

The side slip prevention torque Ty and the steering holding assist torque Tg1 set by the steering control torque calculating means 5A and the steering control torque correcting means 5B corresponding to the side shift in this way are appropriately set in the control torque calculating section 5D. The gains Ky and Kg are multiplied and then added to calculate a steering control torque Tc. Controller 6
Operates the steering actuator 21 on the basis of the steering control torque Tc thus obtained, whereby the steering torque of the driver and the steering control torque Tc of the steering actuator 21 are added, and the power steering It is transmitted to the steered wheels 22 via the device, and steers the steered wheels 22.

By the way, when the road surface is wet, or when there are many puddles on the road surface, the light is easily reflected, so that the luminance of the road surface becomes high, and the luminance difference between the road surface and the white line becomes small. Therefore, it is difficult to distinguish the white line from the normal road surface. Further, when the white line is broken or unclear on the way, or when there is a display or an object close to white near the white line, the white line cannot be recognized. In such a case, in the white line recognition processing in the image information processing means 3, many of the candidate points 15 of the white line 12 do not fall within the error range, and the recognition of the white line 12 from the candidate point 15 cannot be performed. The white line 12 is recognized by performing an interpolation calculation from the inclination between the upper and lower ends of the white line 12 on the screen.

However, when a large number of candidate points 15 on the screen are rejected without being within the error range, it cannot be said that the white line on the road surface can be recognized effectively. Even if the lateral deviation prevention torque Ty and the steering assist torque Tg1 are calculated based on white line information with low accuracy, there is a high possibility that the function of preventing lane departure will not be effectively exhibited.

Therefore, when a certain number or more of the candidate points 15 are rejected, the recognition loss signal is output to the control torque calculation means 5 assuming that the white line recognition is malfunctioning. However, if either one of the left and right white lines 12L and 12R can be effectively recognized, the control can be performed based on the effectively recognized white line 12, so that the recognition lost signal is not output and the left and right white lines 12L and 12R are not output. Only when both 12L and 12R cannot be recognized, a recognition lost signal is output.

When the recognition lost signal is input from the image information processing means 3, the control torque calculation means 5 firstly uses the switching means 5d, which is a functional element of the control torque calculation part 5D,
The means for setting the steering assist torque is switched from the steering control torque correcting means 5B to the substitute steering control torque correcting means 5C. This substitute steering control torque correction means 5C
Is based on the lateral acceleration G calculated by the lateral acceleration calculating means 7 by the steering control torque correcting means 5B.
While g1 is set, the lateral acceleration actually acting on the vehicle 1 is detected by the lateral G sensor, and the detected actual lateral acceleration G '
, The steering assist control can be performed regardless of the state of the white line recognition of the image information processing means 3. For this reason, when white line recognition of the image information processing means 3 becomes spontaneously out of order, switching to the substitute steering control torque correction means 5C and setting the steering maintenance assist torque Tg2 enables the steering to be maintained according to the road condition. It is possible to prevent the control from becoming unstable.

Since the low-pass filter 25 is interposed between the control torque calculating means 5 and the controller 6, the steering assist torque Tg1 is changed to the steering assist torque Tg.
The torque fluctuation at the time of switching to No. 2 can be smoothed, whereby the steering assist torque becomes smoothly continuous, and the steering control can be further stabilized.

The substitute steering control torque correcting means 5C
Sets the steering assist torque Tg2 from a map as shown in FIG. 9, similarly to the steering control torque correcting means 5B, so that the steering assist torque Tg2 is set to the magnitude of the actual lateral acceleration G '. Accordingly, the driver does not feel a sense of discomfort compared to the steering control using the steering assist torque Tg1.

On the other hand, regarding the lateral deviation prevention control using the lateral deviation prevention torque Ty, the lateral deviation amount ΔY, which is the reference for calculating the lateral deviation prevention torque Ty, can be obtained only by the image information from the camera 2. Can not. Therefore, when the recognition lost signal is input, the gain Ky is gradually reduced at a constant speed dKy1. By stopping the lateral displacement prevention control according to the recognition lost signal in this way, it is possible to prevent the driver from feeling uncomfortable due to improper torque application based on unreliable white line information, and to gradually reduce the gain Ky. As a result, it is possible to prevent the driver from feeling uncomfortable because the application of the lateral displacement prevention torque Ty is suddenly stopped or the white line recognition becomes normal and the lateral displacement prevention torque Ty is suddenly applied again.

In this way, when the gain Ky becomes 0 and the application of the lateral displacement prevention torque Ty is stopped, only the steering assist torque Tg2 based on the actual lateral acceleration G 'is changed to the steering control torque Tg.
However, since the actual lateral acceleration G ′ is generated not only by a curved road but also by other factors such as a meandering operation of the vehicle, accurate steering control is not necessarily performed by the steering assist torque Tg2. Cannot be performed, and the driver may feel uncomfortable due to unnecessary torque application. That is, the steering assist torque Tg2 based on the actual lateral acceleration G 'is used when the white line recognition is intermittently malfunctioning and the lateral acceleration calculating means 7 cannot calculate the lateral acceleration G accurately. Is effective for temporarily substituting until normal recovery, but not suitable for permanent use.

Therefore, if the recognition lost signal continues for a predetermined time, it is determined that there is no single white line recognition malfunction.
Similarly to the lateral displacement prevention control, the gain Kg is gradually reduced at a constant speed dKg1, and the operation is stopped for several seconds. In this way, by stopping the steering control by the steering assist torque Tg2 after a predetermined time has elapsed after the input of the recognition lost signal, the continuity of the steering control can be maintained in the case of a single white line recognition failure, and the lateral Lateral acceleration G by acceleration calculation means 7
It is possible to prevent the driver from feeling uncomfortable due to the improper application of torque based on the actual lateral acceleration G ', which is less reliable than a long time, and further to gradually increase the gain Kg.
Can be prevented from suddenly stopping the application of the steering assist torque Tg2 and causing the driver to feel uncomfortable.

When the recognition lost signal continues for a predetermined time or more, both the gains Ky and Kg become 0 and the lane departure prevention control by applying the steering control torque Tc is stopped. Then, the lane departure prevention control by the application of the steering control torque Tc is restarted.
At this time, the switching means 5d switches to the steering control torque correcting means 5B, and the steering assist torque Tg1 is set based on the lateral acceleration G calculated by the lateral acceleration calculating means 7, so that the stable steering is maintained. Control can be performed.

Further, when the lane departure prevention control is restarted, the gains Ky and Kg both gradually increase at the constant speeds dKy2 and dKg2, so that it is possible to prevent the driver from feeling uncomfortable due to sudden torque application. As described above, according to the present lane departure prevention device, when the white line recognition by the image information processing unit 3 becomes abnormal due to the road condition, the actual lateral acceleration G ′ is maintained until the white line recognition becomes normal with respect to steering control. If the malfunction condition continues for a long time, the gain K
Since the control is stopped by gradually decreasing y and Kg, it is possible to prevent the control from becoming discontinuous and giving the driver an uncomfortable feeling.

Further, the steering control torque Tc is smoothed by the low-pass filter 25 and output, so that
There is also an advantage that the control torque for steering generated by the steering actuator 21 can be smoothly continued without abrupt change, and the control for preventing lane departure can be stabilized.

[0089]

As described above in detail, according to the lane departure prevention apparatus of the present invention, the travel lane is estimated from the white line on the road recognized by the white line recognition means, and the own vehicle can recognize the travel lane. Steering control torque is applied by the steering actuator separately from the driver's steering force in a direction to prevent the vehicle from deviating from the traveling lane, and the steering control torque has a magnitude corresponding to the amount of lateral displacement or lateral acceleration of the vehicle. It is possible to apply a steering control torque of an appropriate magnitude according to the degree of the vehicle going to deviate and taking into consideration the curve condition of the road surface, so that guidance for lane departure prevention can be provided. It can be performed accurately according to the situation, and when the white line recognition of the white line recognition unit is not normal, the lateral acceleration detection unit replaces the lateral acceleration calculated by the lateral acceleration calculation unit. Since substituting actual lateral acceleration issued for the calculation of the lateral acceleration corresponding control torque can be upset by the control becomes discontinuous driver of the white line recognition is prevented from feeling uncomfortable.

According to the lane departure prevention device of the present invention, when the white line recognition by the white line recognition means becomes malfunctioning, the application of the control torque corresponding to the lateral deviation amount is stopped by gradually decreasing the control gain. Therefore, it is possible to prevent the driver from feeling uncomfortable due to improper torque application based on unreliable white line information, and the driver may suddenly stop applying the lateral displacement amount control torque and feel uncomfortable. Can be prevented.

Further, according to the lane departure prevention device of the present invention, when the malfunction of white line recognition by the white line recognition means has continued for a predetermined time or more, the control gain is gradually decreased to thereby reduce the actual gain. Since the application of the control torque corresponding to the lateral acceleration based on the lateral acceleration is stopped, the continuity of the control can be maintained by the control torque corresponding to the lateral acceleration based on the actual lateral acceleration in the case of sporadic white line recognition failure, and the reliability is improved. It is possible to prevent the driver from feeling uncomfortable due to the improper torque application based on the low actual lateral acceleration being continued for a long period of time. It is possible to prevent the driver from feeling uncomfortable when the application of the control torque is stopped.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a control torque calculating means according to a lane departure prevention device as one embodiment of the present invention.

FIG. 2 is a block diagram schematically illustrating a configuration of a lane departure prevention device as one embodiment of the present invention.

FIG. 3 is a diagram illustrating image processing for driving lane recognition according to an embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating traveling lane recognition according to an embodiment of the present invention in the order of (a) to (f).

FIG. 5 is a schematic plan view illustrating travel lane recognition.

FIG. 6 is an explanatory diagram for describing calculation of a curvature of a traveling lane.

FIG. 7 is a diagram showing an example of a map for setting a side slip prevention torque applied to the lane departure prevention device as one embodiment of the present invention.

FIG. 8 is a diagram showing another example of a map for setting a side slip prevention torque applied to the lane departure prevention device as one embodiment of the present invention.

FIG. 9 is a diagram illustrating an example of a map for setting a steering assist torque according to the lane departure prevention device as one embodiment of the present invention.

FIG. 10 is a diagram showing another example of a setting map of the steering assist torque according to the lane departure prevention device as one embodiment of the present invention.

11A and 11B are diagrams showing a time change corresponding to input of a recognition lost signal of a control gain according to the lane departure prevention device as one embodiment of the present invention, and FIG. 11A is a diagram showing input of a recognition lost signal; (B) is a diagram showing the time change of the gain Ky, (c) is a diagram showing the time change of the gain Kg and the switching of the steering torque, and the time axes coincide.

FIG. 12 is a diagram showing an example of a configuration of a steering actuator provided in the lane departure prevention device as one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 2 Camera (image information input means) 3 Image information processing means (white line recognition means) 4 Traveling lane estimating means (traveling lane estimating means) 4A Side slip amount calculating means 4B Road curvature calculating means 5 Control torque calculating means 5A Steering corresponding to side slip Control torque calculation means 5B control torque calculation means for steering maintenance 5C control torque calculation means for substitute steering maintenance 5D control torque calculation unit 5d switching means 6 control means (controller) 7 lateral acceleration calculation means 21 steering actuator 25 low-pass filter 27 steering angle Sensor 31 Lateral G sensor (lateral acceleration detecting means) 32 Vehicle speed sensor LC Road center line

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Takashi Ota 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (56) References JP-A-7-81602 (JP, A) JP JP-A-4-108081 (JP, A) JP-A-8-85469 (JP, A) JP-A-4-273301 (JP, A) JP-A-7-110712 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) B62D 6/00

Claims (3)

(57) [Claims] When the vehicle is about to deviate from the travel lane, a steering control torque that the driver can easily overcome is applied by a steering actuator of the vehicle separately from the steering torque applied by the driver in a direction to prevent the deviation from the traveling lane. A lane departure prevention device for guiding lane departure prevention of the vehicle, comprising: image information input means for inputting a road image ahead of the vehicle; and road image information obtained by the image information input means. White line recognizing means for recognizing the white lane of the vehicle, traveling lane estimating means for estimating the traveling lane from the white line recognized by the white line recognizing means, and a reference value of the traveling lane estimated by the traveling lane estimating means. A lateral displacement amount calculating means for calculating a lateral displacement amount of a traveling position of the vehicle; and a lateral acceleration acting on the vehicle from a road curvature of the traveling lane estimated by the traveling lane estimating means. A lateral acceleration calculating means for calculating a lateral displacement amount control torque based on the lateral displacement amount calculated by the lateral displacement amount calculating means, and a lateral acceleration corresponding control based on the lateral acceleration calculated by the lateral acceleration calculating means. Control torque calculating means for calculating a torque, and calculating the steering control torque from the lateral displacement amount control torque and the lateral acceleration corresponding control torque; the steering control torque calculated by the control torque calculation means is Control means for controlling the steering actuator so that the vehicle is deviated from the traveling lane, and lateral acceleration detecting means for detecting actual lateral acceleration applied to the vehicle. When the white line recognition by the white line recognition unit is not normal, the torque calculation unit replaces the lateral acceleration calculated by the lateral acceleration calculation unit with the lateral acceleration. And calculates the lateral acceleration corresponding control torque based on the output said actual lateral acceleration detected by means, the lane departure prevention apparatus. 2. The control torque calculating means, when the white line recognition by the white line recognizing means becomes abnormal, gradually increases the control gain of the control torque corresponding to the lateral shift amount based on the lateral shift amount calculated by the lateral shift amount calculating means. The lane departure prevention device according to claim 1, characterized in that the lane departure prevention device is lowered. 3. The lateral-torque corresponding control based on the actual lateral acceleration detected by the lateral-acceleration detecting means when the white-line recognizing means malfunctions in the white-line recognition for a predetermined time or more. 3. The lane departure prevention device according to claim 1, wherein a torque control gain is gradually reduced.