JP2000315255A - Rear side monitoring device for vehicle and rear side monitoring alarm device for vehicle - Google Patents

Abstract

(57) [Summary] [Problem] A vehicle rear side monitoring apparatus and a vehicle rear side capable of setting a monitoring area corresponding to a lane of a road in a road image without using a white line detected from the road image. Provide a monitoring and warning device. SOLUTION: A monitoring area setting means 31-1 sets a monitoring area corresponding to a lane of a road image obtained by an imaging means 10 imaging a road on the rear side of a vehicle at regular intervals. The optical flow detecting means 31-2 detects an optical flow generated from another vehicle in the monitoring area based on two successive road images, and uses the optical flow detected by the optical flow detecting means to connect the own vehicle and the following vehicle. Monitor the relative relationship with other vehicles. The monitoring area setting means includes two white line positions where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means;
A monitoring area is set in or outside of an area surrounded by a line connecting an infinite point in a road image determined by the detected steering angle of the vehicle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle rear side monitoring device and a vehicle rear side monitoring and warning device, and more particularly, to an image pickup means such as a video camera installed in a vehicle such as an automobile. An image of the road on the rear side of the vehicle is taken, and using the captured road image, the other vehicle approaching from the rear side of the own vehicle traveling is detected, and a warning is issued to the driver to alert the driver. The present invention relates to a rear side monitoring device for a vehicle that monitors a side, and a rear side monitoring and warning device for a vehicle that alerts a driver when a danger is detected as a result of the rear side monitoring.

[0002]

2. Description of the Related Art Conventionally, following vehicles on left and right adjacent lanes adjacent to the own lane in which the own vehicle is traveling are accurately recognized, and when the vehicle attempts to change course, the adjacent lane in that direction is changed. If the following vehicle is running, the driver is warned that there is a risk of collision, and the rear side of the vehicle is monitored to prevent a collision with the following vehicle when changing course. The monitoring alarm device is disclosed in, for example, Japanese Patent No. 2641.
562, JP-A-6-107096 and JP-A-7
It has been proposed in, for example, JP-A-50769.

[0003] These proposed devices use a road image taken by a video camera so that a following vehicle in an adjacent lane can be detected faster and more reliably without performing extra image processing. The lane on the road is recognized by recognizing the white line which is the lane division line, and the monitoring area is set in the adjacent lane by this identification. In the monitoring area set in the road image captured by the video camera, that is, in the adjacent lane The amount of image processing for detecting the approaching following vehicle existing in the vehicle is reduced.

The above-mentioned Japanese Patent Application Laid-Open Nos. 6-107096 and 7-50769 disclose an application to which the detection of an optical flow is applied.
3 and FIG.

FIG. 13 is a block diagram showing a configuration of a conventional apparatus. In FIG. 1, reference numeral 10 denotes an image pickup unit as an image pickup means, which has, for example, a video camera 11. Also, 3
Reference numeral 0 denotes a data processing unit as an arithmetic processing unit, and reference numeral 42 denotes a speaker as alarm means.

[0006] The image pickup unit 10 is disposed at a predetermined position behind the vehicle, for example, at an upper position of a trunk, so as to face the front of the vehicle so as to image a road behind the vehicle. The data processing unit 30
CPU 31 as a central control device that operates in accordance with the operation program; ROM 32 that stores the operation program of CPU 31 and preset values and the like;
RA that temporarily holds necessary data when executing the operation 1
M33. The speaker 42 is disposed inside the vehicle, and notifies a driver or the like of danger by generating a voice or an alarm sound as needed in accordance with a drive signal from the CPU 31 of the data processing unit 30.

FIG. 14 is a view for explaining changes in the image picked up by the image pick-up unit 10 mounted on the rear part of the host vehicle as described above. FIG. 14A shows the image picked up at time t. (B) shows a captured image at time t + Δt. In each of these figures, reference numeral 200 denotes a following vehicle traveling behind the host vehicle, and 300 denotes a road 500.
The road sign placed adjacent to the road, 400 is also the road 5
The building is located adjacent to 00.

Now, assuming that the own vehicle is traveling straight on a flat road, the road sign 300 and the building 400 are imaged at a small distance from the own vehicle as the time elapses, that is, as the own vehicle travels. In the figure, the road sign 300 and the building 400 in the captured image at the time t in FIG.
14B, that is, the road sign 300 and the building 400 in the captured image at the time t + Δt.
The road sign 300 and the building 400 in (b) are imaged smaller. Hereinafter, the optical flow will be described with reference to these drawings.

In these figures, regarding a plurality of corresponding points set in a captured image, for example, a point of interest in another vehicle 200, a point of interest in a road sign 300, and a point of interest in a building 400, a point of interest for each time, that is, a time point Each point of interest 201a, 202a, 3a at t [FIG. 14 (a)]
01a, 302a, 303a, 401a and 402a
And each point of interest 2 at time t + Δt [FIG. 14 (b)].
01b, 202b, 301b, 302b, 303b, 4
By combining the corresponding points of interest for 01b and 402b, the velocity vectors 201F, 202F, 301F, and 302 shown in FIG.
F, 303F, 401F and 402F are obtained. The obtained velocity vector is an optical flow.

Here, this optical flow is defined as an FOE (FOE) defined as a point at infinity or a vanishing point on the screen.
ocus of Expansion). This FOE corresponds to one point indicating the direction directly opposite to the traveling direction of the own vehicle on the image when the vehicle is traveling straight. Then, in the traveling state of the own vehicle, the optical flow of the object moving away from the own vehicle is a vector in the convergence direction toward the FOE, and the optical flow of the object approaching the own vehicle is a vector in the diverging direction moving away from the FOE. Accordingly, FIG.
Since the optical flow of the subsequent other vehicle 200 indicated by 02F is a vector in the direction of divergence, the other vehicle is approaching the own vehicle, in other words, it is a vehicle running at a higher speed than the own vehicle. I understand.

Further, regarding the magnitude of the optical flow, the magnitude of the optical flow increases as the difference in the distance between the host vehicle and the target object per unit time, that is, the speed difference, increases, and the distance between the host vehicle and the target object increases. It becomes larger as the relative distance is shorter. This will be described with reference to the drawings.

FIG. 15 is a diagram showing an optical arrangement of the image pickup unit 10. As shown in FIG. In the figure, 11a is a lens included in the video camera of the imaging unit 10, 11b is an image plane also included in the video camera, f is a distance from the lens 11a to the image plane 11b, and P (X _a , Y _a ,
Z _a ) is an arbitrary point on another following vehicle, p (x _a , y)
_a ) is a point corresponding to the point P on the image plane 11b.

In this case, the relationship of the following equation (1) is obtained from the similarity ratio of the triangles. x _a = f · X _a / Z _a (1) The following equation (2) is obtained by modifying this equation (1) and performing time differentiation. _{X a '= (Δx a /} Δt · Z a + x a · Z a') / f ··· (2) Further, x-direction component u of the optical flow is expressed by the following equation (3). u = Δx _a / Δt (3) Accordingly, the following equation (4) can be obtained from the equation (3). _{Z a = (f · X a} '-x a · Z a') / u ··· (4)

Here, Z _a ′ in the above equation (4) represents another vehicle traveling in the same lane or an adjacent lane (reference numeral 20 in FIG. 14).
0) and the own vehicle on which the imaging unit 10 is mounted, that is, the relative speed. If this relative speed is -α, the above equation (4) becomes the following equation (5). Z _a = (f · X _a ′ + x _a α) / u (5) Therefore, the x-direction component u of the optical flow can be expressed as the following equation (6). _{u = (f · X a '} + x a α) / Z a ··· (6) In addition, it can be obtained in the same manner for the Y-coordinate Y _a of the point P.

Therefore, from the above equation (6), as Z is smaller, that is, as the distance to the following vehicle or another vehicle 200 traveling in the adjacent lane is smaller, or α is larger, that is, as other vehicle 200
The larger the speed difference between the two, the larger the x component of the optical flow. This is the same for the Y direction. Therefore, the optical flow becomes longer as the distance to the following other vehicle 200 becomes smaller, and further, as the speed difference between them becomes larger, the direction of the optical flow diverges from the FOE and the length of the optical flow becomes shorter. It can be seen that the longer the danger, the greater the danger to the following vehicle or the adjacent vehicle.

Therefore, when the optical flow is the vector in the divergence direction described above and its magnitude is large, the data processing unit 30 determines whether the target object exists at a position close to the own vehicle or not. It is considered that the vehicle is approaching at a speed higher than that of the vehicle, and it is determined that the risk is high. When it is determined that the risk is high, the driver is notified by the speaker 42 to that effect.

By repeating the above-described processing at all points of the image at the time t, the optical flow of the entire image can be obtained, and the risk of each object can be obtained. Then, the driver is warned by sounding an alarm according to the magnitude of the required degree of danger, thereby supplementing the finite cognitive ability possessed by humans, which may lead to the above-mentioned large accident. No dangerous situations or actual major accidents are prevented.

In the prior art, as shown in FIG. 16, by detecting the white lane of the lane on which the vehicle is traveling on a three-lane straight highway, the traveling lane of the vehicle and the lateral lane thereof are detected. By determining the monitoring area by identifying the adjacent lane area, the processing time for those that do not need to be monitored is reduced, and the processing speed is increased. Then, the FOE point is obtained from the extension of the detected white line, and the optical flow is obtained radially from the FOE point in each of the own lane area and the adjacent lane area, thereby detecting the approaching vehicle 200 to the own vehicle. Since the recognition is performed based on the size of the flow, the danger degree of the other vehicle 200 traveling in the rear or adjacent lane can be automatically determined, and no special distance meter is required. It has advantages and is effective.

Among the currently proposed optical flow detection methods, those which have reached a level close to practical use are correlation methods. The correlation method needs to search for the corresponding point of the set window in all directions in the surrounding area and calculate the correlation value. There is also an advantage that an optical flow can be obtained relatively accurately even for a complicated image as described above.

As described above, in the general correlation method, when obtaining an optical flow for an image at a certain time t = T, all the pixels of the image at a time t = T are calculated as follows.
In the image at time t = T−ΔT, each pixel is
Since it is necessary to search which pixel corresponds to all directions, there is a problem that the amount of calculation becomes enormous and an erroneous correspondence occurs. That is, when searching for corresponding points,
It can be said that the search in all directions with respect to all the pixels causes a huge amount of calculation and a large number of erroneous responses. Therefore, it is considered to set a monitoring area to solve the problems in processing time and detection accuracy.

[0021]

However, Japanese Patent No. 264
As shown in No. 1562, in order to set a monitoring area, a white line which is a lane division line is detected or recognized by using a road image captured by a video camera. Requires a relatively long time, and there is a limit in shortening the entire processing time. In particular, it is extremely difficult to recognize a white line while traveling on a curved road. Also, when the white line cannot be recognized, such as at night or in rainy weather,
There is also a problem that it becomes impossible to set a monitoring area.

Accordingly, the present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above problem, and has been made in consideration of the following. It is an object of the present invention to provide a vehicular rear side monitoring / warning device that warns a driver when a danger is detected as a result of the side monitoring device and the rear side monitoring.

[0023]

Means for Solving the Problems The invention according to claim 1 which has been made to solve the above-mentioned problems is, as is apparent from the basic configuration diagram of FIG. Image capturing means 1 for capturing roads and obtaining road images at regular intervals
0 and a monitoring area setting means 31-1 for setting a monitoring area corresponding to the lane of the road in the road image obtained by the imaging means.
And an optical flow detecting unit 31-2 for detecting an optical flow generated from another vehicle within the set monitoring area based on two consecutive road images obtained at regular intervals by the imaging unit. A rear-side monitoring device for a vehicle for monitoring a relative relationship between a host vehicle and another succeeding vehicle using an optical flow detected by the optical flow detection unit, a steering angle detection unit 51 for detecting a steering angle of the vehicle Wherein the monitoring area setting means detects two known white line positions where white lines on both sides of the own lane in the road image captured by the imaging means intersect with the outer edge of the road image, and detects the steering angle detection means. The monitoring area may be set within or outside an area surrounded by a line connecting an infinity point in a road image obtained by the imaging unit and determined by the steering angle of the vehicle. Lies in the vehicular rear side monitoring system according to claim.

In the vehicle rear side monitoring apparatus according to the first aspect of the present invention, the image pickup means 10 picks up an image of a road on the rear side of the vehicle mounted on the vehicle and generates a road image at regular time intervals. The monitoring area setting means 31-1 sets a monitoring area corresponding to the lane of the road in the obtained road image. Optical flow detecting means 31-2 detects an optical flow generated from another vehicle within a monitoring area set based on two consecutive road images obtained at predetermined time intervals by the imaging means, and detects optical flow. The relative relationship between the own vehicle and the following other vehicle is monitored using the optical flow detected by the means. The monitoring area setting unit is configured to capture an image determined by two white line positions where the white lines on both sides of the own lane captured by the imaging unit intersect with the outer edge of the road image obtained by the imaging unit and the steering angle of the vehicle detected by the steering angle detection unit 51. A monitoring area is set within or outside of an area surrounded by a line connecting an infinite point in the road image obtained by the means. The positions of two white lines where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means are known in advance, and the point at infinity in the road image is also determined by the steering angle of the vehicle detected by the steering angle detection means 51. Since the inside or outside of the area surrounded by the line connecting them is set as the monitoring area, it is not necessary to detect the white line itself to divide the monitoring area, and the infinity point that moves according to the steering angle of the vehicle also corresponds to the steering angle Therefore, the monitoring area set near the point at infinity is also somewhat accurate.

According to a second aspect of the present invention, in the vehicle rear side monitoring device according to the first aspect, the monitoring area setting means includes:
The infinity point includes a steering angle-infinity point storage means 32-1 in which the infinity point is stored in advance corresponding to a steering angle of the vehicle, and the infinity point is
A vehicle rear side monitoring apparatus characterized in that a value corresponding to the steering angle detected by the steering angle detection means is read from the steering angle-infinity point storage means and determined.

In the vehicle rear side monitoring apparatus according to the second aspect of the present invention, the steering angle-infinity point storage means 32 is provided.
-1 stores the point at infinity in advance corresponding to the steering angle of the vehicle, and reads out the point corresponding to the steering angle detected by the steering angle detection means from the steering angle-infinity point storage means to determine the infinity point. Since the monitoring area is set using the monitoring area, the monitoring area can be determined only by detecting the steering angle without any troublesome operation such as computation.

According to a third aspect of the present invention, in the vehicle rear side monitoring device according to the first or second aspect, the monitoring area setting means stores the positions of the two white lines in advance corresponding to the steering angle of the vehicle. And the two white line positions are determined by reading from the steering angle-white line position storage means the one corresponding to the steering angle detected by the steering angle detection means. A rear side monitoring device for a vehicle characterized by the above.

In the vehicle rear side monitoring device according to the third aspect of the present invention, the steering angle-white line position storage means 32-
2 stores two white line positions in advance corresponding to the steering angle of the vehicle, and reads out the position corresponding to the steering angle detected by the steering angle detecting means from the steering angle-white line position storage means to determine the two white line positions determined. Since the monitoring area is set using the monitoring area, the monitoring area can be determined only by detecting the steering angle without any troublesome operation such as computation.

According to a fourth aspect of the present invention, in the vehicle rear side monitoring device according to the first or second aspect, the monitoring area setting means sets the two white line positions in a road image obtained by the imaging means. A rear side monitoring device for a vehicle, characterized in that the outer edge is determined by image processing.

In the vehicle rear side monitoring apparatus according to the fourth aspect of the present invention, the monitoring area is determined by using two white line positions determined by performing image processing on the outer edge of the road image obtained by the imaging means. Since it has been set, it is possible to perform image processing on only a small area,
A monitoring area can be defined.

According to a fifth aspect of the present invention for solving the above-mentioned problem, as is apparent from the basic configuration diagram of FIG. 1B, an image of a road mounted on a vehicle and located on the rear side of the vehicle is taken. Imaging means 10 for obtaining a road image at predetermined time intervals, a monitoring area setting means 31-1 for setting a monitoring area corresponding to the lane of the road in the road image obtained by the imaging means, Optical flow detecting means 31-2 for detecting an optical flow generated from another vehicle in the set monitoring area based on two successive road images obtained every time, and the optical flow detecting means In the vehicle rear side monitoring device that monitors the relative relationship between the host vehicle and the following other vehicle using the detected optical flow, the monitoring area setting unit includes:
A straight line detecting means 31-3 for performing edge processing on the road image obtained by the imaging means to detect a plurality of straight lines reaching a position where an infinite point exists; and an intersection of the plurality of straight lines detected by the straight line detecting means. And infinity point determination means 31-4 for determining as an infinity point in the road image, wherein two white lines on both sides of the own lane taken by the imaging means intersect with the outer edge of the road image obtained by the imaging means. Rear side monitoring for a vehicle, wherein the monitoring area is set within or outside an area surrounded by a line connecting a white line position and an infinity point in the road image determined by the infinity point determination means. Exists in the device.

According to a fifth aspect of the present invention, in the vehicle rear side monitoring device, the monitoring area setting means performs edge processing on the road image obtained by the straight line detecting means 31-3 by the imaging means to determine an infinity point. When a plurality of straight lines reaching the existing position are detected, the intersection of the plurality of straight lines detected by the infinity point determination means 31-4 is determined and used as an infinity point in the road image, and two white line positions and infinity points are determined. A monitoring area is set inside or outside of an area surrounded by a line connecting an infinite point in the road image determined by the far point determining means. The white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means 2
The positions of two white lines are known in advance, and the point at infinity in the road image is determined by the intersection of a plurality of straight lines detected by image processing.
Moreover, the inside or outside of the area surrounding the line connecting them is defined as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area, and the point at infinity can be easily and accurately determined. The monitoring area set near the distant point is also somewhat accurate.

Claim 6 has been made to solve the above problem.
The disclosed invention is, as is apparent from the basic configuration diagram of FIG. 1 (c), an image pickup means 10 mounted on a vehicle to image a road on the rear side of the vehicle and obtains a road image at regular time intervals, and Monitoring area setting means 31-1 for setting a monitoring area corresponding to the lane of the road in the road image obtained by the means, and the setting based on two successive road images obtained at predetermined time intervals by the imaging means. Optical flow detection means 31-2 for detecting an optical flow generated from another vehicle within the monitored area, and using the optical flow detected by the optical flow detection means to communicate between the host vehicle and another subsequent vehicle. In the rear side monitoring device for a vehicle that monitors a relative relationship, the monitoring area setting unit may determine whether a stationary object in two road images that are consecutive with each other at regular time intervals obtained by the imaging unit. Stationary optical flow detecting means for detecting a plurality of optical flow that occurs 31-5
And an infinity point determining means 31-6 for determining a convergence point of the optical flow detected by the stationary object optical flow detecting means as an infinity point in the road image. Of the road image determined by the infinity point determining means determined by the two white line positions where the white lines on both sides of the road intersect the outer edge of the road image obtained by the imaging means and the steering angle of the vehicle detected by the steering angle detecting means. The present invention resides in a rear side monitoring device for a vehicle, wherein the monitoring region is set inside or outside a region surrounded by a line connecting the point at infinity.

In the rear side monitoring apparatus for a vehicle according to the present invention, the monitoring area setting means may be arranged so that the stationary object optical flow detecting means 31-5 comes and goes at regular intervals obtained by the imaging means. When a plurality of optical flows generated from a stationary object in one road image are detected, the convergence point of the optical flow detected by the infinity point determination means 31-6 is determined and used as an infinity point in the road image,
A monitoring area is set inside or outside of an area surrounded by a line connecting two white line positions and an infinity point in the road image determined by the infinity point determination means. The positions of two white lines where the white lines on both sides of the own lane intersect the outer edge of the road image obtained by the imaging means are known in advance, and the point at infinity in the road image is determined by the convergence point of the optical flow detected by the image processing. The inside or outside of the area surrounded by the connecting line is set as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area, and the point at infinity can be easily and accurately determined. The monitoring area set in the vicinity is also somewhat accurate.

Claim 7 has been made to solve the above problem.
The disclosed invention is, as is apparent from the basic configuration diagram of FIG. 1 (d), an image pickup means 10 mounted on a vehicle to image a road on the rear side of the vehicle and obtains a road image at regular intervals, and Monitoring area setting means 31-1 for setting a monitoring area corresponding to the lane of the road in the road image obtained by the means, and the setting based on two successive road images obtained at predetermined time intervals by the imaging means. Optical flow detection means 31-2 for detecting an optical flow generated from another vehicle within the monitored area, and using the optical flow detected by the optical flow detection means to communicate between the host vehicle and another subsequent vehicle. The rear side monitoring device for a vehicle for monitoring the relative relationship includes a vehicle speed detecting means 53 for detecting a speed of the vehicle, and a steering angle detecting means 51 for detecting a steering angle of the vehicle. The setting means has a road shape estimating means 31-7 for estimating a traveled road shape based on a past steering angle detected by the steering angle detecting means and a past vehicle speed detected by the vehicle speed detecting means, The monitoring area is set within or outside a region surrounded by two white line positions where white lines on both sides of the own lane imaged by the imaging unit intersect the outer edge of the road image obtained by the imaging unit and the estimated road shape. A rear side monitoring device for a vehicle characterized by the above.

In the vehicle rear side monitoring apparatus according to the present invention, the monitoring area setting means includes a past steering angle detected by the steering angle detecting means 51 and a past vehicle speed detected by the vehicle speed detecting means 53. Thus, the road shape estimating means 31-7 estimates the road shape up to the point at infinity, and sets a monitoring area inside or outside the area surrounded by the two white line positions and the estimated road shape. The positions of two white lines where the white lines on both sides of the own lane intersect the outer edge of the road image obtained by the imaging means are known in advance, and the shape of the road that has been traveled in the road image is determined by detection. The inside or outside of the surrounding area is defined as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area, and the monitoring area can be easily and accurately determined. Will be accurate.

According to an eighth aspect of the present invention, in the vehicle rear side monitoring device according to the first or seventh aspect, the monitoring area setting means is configured to detect the position of the two white lines by the steering angle detecting means. The present invention resides in a rear side monitoring device for a vehicle, which is selected by a steering angle.

In the vehicle rear side monitoring apparatus according to the present invention, the monitoring area setting means sets the monitoring area by selecting two white line positions based on the steering angle of the vehicle detected by the steering angle detecting means. As a result, the monitoring area near the own vehicle is also accurate.

According to a ninth aspect of the present invention, in the vehicle rear side monitoring device according to the seventh aspect, the monitoring area setting means stores the two white line positions in advance in correspondence with the steering angle of the vehicle. A corner-white line position storage means 32-2;
The position of one white line is determined by reading out the position corresponding to the steering angle detected by the steering angle detection means from the steering angle-white line position storage means.

In the vehicle rear side monitoring apparatus according to the ninth aspect of the invention, the monitoring area setting means includes a steering angle-white line position storage means 32-2 which stores two white line positions in correspondence with the steering angle of the vehicle. Since the monitoring area is set using the two white line positions determined by reading out the data corresponding to the steering angle detected by the steering angle detection means from the steering angle-white line position storage means, the monitoring area is set in advance. The monitoring area of the portion close to the host vehicle can be accurately determined without the need for a complicated operation or other processing work only by detecting the monitoring area.

According to a tenth aspect of the present invention, in the vehicle rear side monitoring device according to the fifth, sixth or seventh aspect, the monitoring area setting means sets the two white line positions on the road obtained by the imaging means. A rear-side monitoring device for a vehicle is characterized in that an outer edge of an image is determined by image processing.

According to the tenth aspect of the present invention, the monitoring area is set by using two white line positions determined by performing image processing on the outer edge of the road image obtained by the imaging means. Therefore, it is possible to accurately determine a monitoring area close to the host vehicle by performing image processing on a small and small area without performing a complicated operation or other processing operation.

Claim 1 has been made to solve the above problem.
The invention according to claim 1, wherein the monitoring area is set outside the enclosed area as shown in the basic configuration diagram of FIG. 1 (e). A monitoring device, a turn signal detecting means 52 for detecting an operation of the turn signal and an operation direction thereof, and a result of monitoring by the rear side monitoring device for a vehicle, the own vehicle is located within the monitoring area in the operation direction detected by the turn signal detecting means. And a warning means 40 for giving a warning to the driver when there is another vehicle approaching from the rear side of the vehicle.

In the vehicle rear side monitoring / warning apparatus according to the eleventh aspect, the outside of the enclosed area, that is, an area including an adjacent lane adjacent to the own lane is a monitoring area, and When there is another vehicle approaching from the rear side of the own vehicle within the monitoring area in the lane change direction detected by the detecting means 52, the warning means 40 gives a warning to the driver. Therefore, it is not necessary to detect the white line itself, and a necessary alarm can be given in a short processing time.

[0045]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of an apparatus to which the present invention is applied.
Reference numeral 0 denotes an imaging unit as an imaging unit, 20 denotes a storage unit that holds image data from the imaging unit 10, 30 denotes image processing based on image information from the imaging unit 10, and processing for monitoring a relative relationship with another vehicle. , A warning unit as warning means for generating a warning, and a signal input unit 50 for inputting a signal indicating operation information when changing the traveling direction of the vehicle.

The image pickup section 10 comprises a video camera 11. Then, this video camera 11
As described above, it has a lens (indicated by reference numeral 11a in FIG. 13) and an image plane (indicated by 11b). The video camera 11 of the imaging unit 10 is attached to the upper part or the rear end of the trunk at the rear of the vehicle, facing the rear of the vehicle. And this video camera 11
Is configured to capture a road image on the rear side of the vehicle. Then, the video camera 11 outputs road image information on the rear side of the vehicle to a CPU 31 (described later) of the data processing unit 30.

The storage unit 20 has a first frame memory 21 and a second frame memory 22 for holding the road image information from the image pickup unit 10, and a divergent optical flow memory 23 for holding the optical flow in the divergent direction. ing.

The first frame memory 21 and the second frame memory 22 constituting the storage section 20 are configured as a matrix-like memory having m rows and n columns, for example, 512 pixels × 512 pixels. Each of the memories 21 to 23 is connected to the CPU 31 of the data processing unit 30 in a readable and writable manner.

The data processing unit 30 includes a CPU 31 serving as a central control device that operates according to an operation program.
It has a ROM 32 for storing an operation program of the PU 31 and a set value given in advance, and a RAM 33 for temporarily storing data required when the CPU 31 executes an operation.

The alarm section 40 includes a display 41 and a speaker 42.
And The display 41 is configured by an LCD or the like, and displays an image captured by the video camera 11, or displays a message when the data processing unit 30 (CPU 31) determines that there is a risk of contact with another vehicle. Is displayed to inform the driver of the danger. The speaker 42 generates a voice such as voice guidance or a warning sound based on a voice signal from the data processing unit 30. When the data processing unit 30 determines that there is a risk of contact with another vehicle, the driver is informed of the danger by voice using this voice.

The signal input section 50 includes a steering angle sensor 51 as a steering angle detecting means for detecting a steering angle of a steering wheel or a steering wheel (generally, a front wheel) of the vehicle, a state of operation of the turn signal mechanism by the driver, and a state of the operation of the turn signal mechanism. A turn signal (turn signal) detection switch 52 serving as a turn signal detection means for detecting an operation direction is provided. The turning information of the vehicle is detected by the steering angle sensor 51, and the driver turns the vehicle to the left or right by the turn signal detection switch 52. Turn instruction information from the turn signal mechanism operated when turning is detected.

The operation of the specific example having the above configuration, that is, the control operation by the data processing unit 30 will be described with reference to a flowchart. In this specific example, first, in step S110 of the flowchart in FIG. 3, that is, the main flowchart in the specific example, an image acquisition process is performed, and the CPU 31 of the data processing unit 30 functions as a monitoring area setting unit 31-1.

The image acquisition processing in step S110 is for acquiring image information for setting a monitoring area when performing the first processing.
By the processing of 10, for example, a road image on the rear side shown in FIG. 4 is obtained.

This road image exemplifies an image from the own vehicle traveling on a motorway such as an expressway. Since the video camera 11 is attached to the rear part of the vehicle toward the rear side, The image is a direct view of the rear side of the vehicle. As shown in FIG.
White lines 510 and 520, which are drawn on zero and are composed of dashed lines dividing the own lane and the adjacent lane, and which allow lane change, and white lines 530 which are made up of continuous straight lines which delimit the side road and which prohibit lane change
And 540, and the wall 6 standing on both sides of the road 500
00 is an image that disappears at the center position in the horizontal direction and 1/3 position in the vertical direction on the image, and this vanishing point is the FOE. The information of the acquired road image is stored in the first frame memory 2 of the storage unit 20.
1 is stored.

Further, as described above, this road image
Since the vehicle is attached to the rear side of the vehicle, the right side in the road image corresponds to the left side based on the traveling direction, and the left side in the road image corresponds to the right side based on the traveling direction. Hereinafter, description will be made in the left-right direction based on the road image.

FO indicating the vertical position of the above-mentioned FOE
The E-line L is determined by the angle of view, lens aberration, camera installation parameters (height, depression angle) of the video camera 11 attached to the rear part of the vehicle toward the rear side,
For example, it is set at a position 100 m behind. In addition, road 50
Also, the white lines 510 and 520, which are composed of broken lines dividing the own lane and the adjacent lane, which are drawn on the zero and cross lanes, intersect the outer edges of the image.
Angle of view, lens aberration, camera installation parameters (height,
Angle of depression). Therefore, the monitoring area of the own lane is set inside the area surrounded by the line connecting the white line positions W1 and W2 intersecting with the outer edge of the image and the point at infinity FOE, and the monitoring area of the adjacent lane is set outside the area particularly surrounded by the FOE line L Can be set respectively.

The FOE line L and the FOE on the line
Does not change even if the traveling direction of the vehicle changes in each of the two road images acquired one after another at regular time intervals. The position of the FOE in the image moves when the traveling direction of the vehicle changes, and does not match the FOE in the subsequent image. When the vehicle turns to the right, for example, the position of the point FOE at infinity on the previous image moves to the position of FOE 'as shown in a simplified diagram in FIG. Road 5
The white lines 510 and 520 that are drawn on 00 and are composed of dashed lines that separate the own lane and the adjacent lane, and that allow lane change, intersect with the outer edge of the image. The white line positions W1 and W2 also run in the middle of the linear own lane. As long as the direction of travel of the vehicle changes, it moves from W1 and W2 to W1 'and W2' as shown in a simplified diagram in FIG.

Therefore, when the monitoring area is fixedly set by the white line positions W1 and W2 and the infinity point FOE despite the change of the traveling direction of the vehicle, the infinity point F
Regarding the other vehicle located near the OE, that is, about 100 m behind, the obtained image of the other vehicle is extremely small. Therefore, it is erroneously determined that the vehicle exists in the own lane even though the vehicle actually exists in the adjacent lane. Or, conversely, another vehicle existing in the own lane is erroneously determined to be present in the adjacent lane. In this regard, the obtained image is relatively large for the other vehicle close to the own vehicle. Therefore, even if the vehicle is actually moving to W1 'and W2' or using the fixed W1 and W2, the presence of the other vehicle is There is almost no misjudgment of the region to be performed.

Therefore, when the traveling direction of the vehicle is changed, in a simplified manner, the own lane is located inside and outside the area surrounded by the line connecting the moved FOE 'and the white line positions W1 and W2 intersecting the outer edge of the image. By setting the monitoring area and the monitoring area of the adjacent lane, other vehicles in the own lane and the adjacent lane can be monitored without erroneous determination. Of course,
Strictly, it is preferable to set the monitoring area of the own lane and the monitoring area of the adjacent lane inside and outside the area surrounded by the line connecting the moved FOE 'and W1' and W2 '.

Incidentally, the moving amount ΔFO of the point FOE at infinity
E is proportional to the amount of change in the traveling direction of the vehicle, and can be obtained by calculation by multiplying a preset proportionality constant by a steering angle that determines the amount of change in the traveling direction. R is the table of the angle and the amount of FOE movement
The steering angle-infinity point storage means 32 is stored in a predetermined area in the OM 32.
It can also be determined by preparing the value as −1 and reading the movement amount using the steering angle as an address. The former is R
Although the storage capacity of the OM is not required, the latter is suitable for high-speed processing because the calculation is unnecessary.

On the other hand, the amount of movement of the white line positions W1 and W2 is also proportional to the amount of change in the traveling direction of the vehicle, and can be obtained by calculation by multiplying a preset proportional constant by the steering angle for determining the amount of change in the traveling direction. As shown in FIG. 7, the coordinates of the new white line positions W1 and W2 obtained by adding the movement amounts obtained in advance are stored in a table together with the steering angle and the movement amount of the FOE. It can be prepared in advance as the storage means 32-2, and can be determined by reading the white line position using the steering angle as an address.

In the following step S120, a monitoring area setting process is performed. This monitoring area setting processing is performed by
As an example, this is performed according to the flowchart of FIG. Hereinafter, description will be made with reference to the flowchart of FIG. In the monitoring area setting process, first, in step S210a, the steering angle signal from the sensor 51 is converted from analog to digital and read as steering angle data, and the steering angle of the steering wheel or the steering wheel of the vehicle (generally, the front wheel) is calculated. To detect. Next, in step S220a, using the steering angle detected in step S210a as an address, the movement amount .DELTA.FOE of the infinite point FOE is read from the table of FIG. 6, and the infinity point FOE 'moved by the read movement amount .DELTA.FOE is determined. Next, in step S230a, as shown in FIG. 9, the white line was surrounded by a line connecting the two known white line positions W1 and W2 intersecting the outer edge of the road image and the infinity point FOE 'determined in step S220a. The monitoring area is set inside or outside the area, and the process returns to the original flowchart.

In the flowchart of FIG. 8, two known white line positions W1 and W2 that do not move with the steering angle are used as the two white line positions where the white line intersects the outer edge of the road image. However, the white line position W1 'that moves with the steering angle is used. When W2 'and W2' are used, white line positions W1 'and W2' represented by x and y coordinates corresponding to the steering angle are read from the table shown in FIG. 7 in the above-described step S230a, and the white line positions are determined in step S220a. Infinity point FO
The monitoring area may be set within or outside the area surrounded by the line connecting E '.

The infinity point FO moved according to the steering angle
Although a table is used to determine E ′ and white line positions W1 ′ and W2 ′, the table may be obtained by calculation by multiplying the steering angle by a constant, but as shown in FIG. The minimum image processing area is set at the outer edge of the road image corresponding to the range of the white line position that moves accordingly, and the two white line positions where the white line intersects the outer edge of the road image have higher luminance than the other portions. Paying attention, the white line positions W1 'and W2' may be detected and determined by the image processing of this image processing area.

As a method of determining the infinite point FOE, a road image is edge-processed, Hough-transformed, and a white line 5 on the road is obtained.
Any arbitrary straight lines reaching the position where the infinity point exists, such as 30 and 540 and the wall 600 standing on both sides of the road 500, are detected, and the intersection of the plurality of straight lines is determined as the infinity point. And a method of detecting a plurality of optical flows generated from stationary objects in two road images that are successively arranged at predetermined time intervals, and determining a convergence point of the optical flows as a point at infinity.

In order to carry out the former method, the CPU 31 of the data processing unit 30 operates according to a predetermined program to perform edge processing on the road image obtained by the video camera 11 so as to reach a position where an infinite point exists. And an infinity point determination unit 31-4 that determines an intersection of a plurality of detected straight lines as an infinity point in the road image. The processing itself for detecting a straight line is well known without showing a specific example. Further, in order to carry out the latter method, the CPU 31
Video camera 1 operated by a predetermined program
A stationary object optical flow detection means 31-5 for detecting a plurality of optical flows generated from stationary objects in two road images which are successively arranged at regular time intervals obtained by step 1;
It functions as an infinity point determination unit 31-6 that determines a convergence point of the detected optical flow as an infinity point in the road image. Note that a process for detecting an optical flow is also well known.

As described above with reference to FIG. 5, when the traveling direction of the vehicle changes, the FOE on the previously acquired road image is the same as the FOE on the previously acquired road image. Move up sequentially. When the vehicle is traveling on a curved road, the steering angle is continuously maintained at a constant angle or finely adjusted, so that the own vehicle travels along with the movement of the FOE on the previously acquired road image. The own lane and the adjacent lane are located far from the current FOE point. In such a case, as described above, simply connecting the two white line positions intersecting with the outer edge of the road image and the point at infinity in the road image by a line results in 1
It becomes impossible to determine whether the other vehicle behind the vehicle is within the own lane or the adjacent lane.

Therefore, the shape of the road on which the host vehicle has traveled is estimated based on the past steering angle and the vehicle speed during the traveling of 100 m, and monitoring is performed based on the estimated two white line positions intersecting the outer edges of the road image and the estimated road shape. Set an area.

In order to estimate the road shape, as shown in FIG. 11, every time a road image is acquired at regular time intervals, a signal from a steering angle sensor 51 as a steering angle detecting means of the signal input unit 50 is used. While obtaining the steering angle θ, the vehicle speed v is detected by a speed signal from a speed sensor (not shown) as a vehicle speed detecting means of the signal input unit 50, and the x, y coordinate positions of the own vehicle on the road image are sequentially acquired. In addition, the deviation amount ΔFOE between the current FOE position and the own lane position 100 m behind and the trajectory information are obtained. Then, as shown in FIG.
By connecting the two white line positions W1 and W2 and FOE 'with a curve along the road shape indicated by the coordinate points, respective monitoring areas of the own lane and the adjacent lane are set inside and outside the area surrounded by the curve. Therefore, the CPU 31 operates according to a predetermined program, and estimates a road shape that has been traveled based on the past steering angle detected by the steering angle sensor 51 and the past vehicle speed detected by the vehicle speed sensor. Function as 7.

After setting the monitoring area by the various methods described above, step S in the flowchart of FIG.
Proceed to 130. In step S130, an optical flow detection process is performed. Therefore, the CPU 31 operates according to a predetermined program and detects an optical flow generated from another vehicle within a set monitoring area based on two successive road images obtained at regular intervals by the video camera 10. Function as optical flow detecting means 31-2. This optical flow detection processing is performed on the monitoring area set in step S120. When the monitoring area is set in the adjacent lane on both sides of the own lane, a predetermined value is obtained from the road image stored in the first frame memory 21. The same monitoring area is set for the captured image captured with a delay of time Δt and stored in the second frame memory 22. And this step S
At 130, at an image composing point in the road image at time t and an image composing point in the captured image at time t + Δt,
The moving direction and the moving amount between the corresponding points are detected as optical flows.

Then, in step S140, a risk calculation process is performed. That is, in this step S140, of the optical flows acquired in step S130, the optical flows 201F and 201F described above are used.
For the optical flow in the divergent direction like 02F,
The size (length) is weighted and digitized. In addition,
In this calculation process, the threshold may be set at several levels, and the risk level may be calculated.

In the following step S150, based on the risk calculated in step S140, if this risk exceeds a certain threshold, it is determined that there is danger. If a risk level is given, it is determined to be dangerous if this level exceeds a specified value. Then, if it is determined in this determination process that there is danger, an alarm process is executed in step S160. On the other hand, if it is determined that there is no danger, a series of processes is terminated and the above-described step S160 is repeated.
The process from 110 is executed (RTS).

In the alarm process of step S160, an audio signal is sent to the speaker 42 of the display / alarm unit 40,
By generating voice guidance or an alarm sound from the speaker 42, the driver is warned, a message or the like is displayed on the display 41, and the danger is notified to the driver with an image. When the level of the danger is very high, a braking mechanism (not shown) is operated to perform an operation of braking the vehicle. Then, this step S16
When the alarm process of “0” ends, a series of processes ends, and the processes from step S110 described above are executed again (RT
S).

[0074]

As described above, according to the first aspect of the present invention, the positions of two white lines where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means are known in advance, The point at infinity is also determined by the steering angle of the vehicle, and the inside or outside of the area surrounded by these connecting lines is defined as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area. Since the infinity point moving by the angle can be easily determined in accordance with the rudder angle, the monitoring area set near the infinity point has a certain degree of accuracy in the rear side monitoring device for a vehicle. Can be

According to the second aspect of the present invention, the point at infinity is stored in advance corresponding to the steering angle of the vehicle, and the point corresponding to the detected steering angle is read out and monitored using the point at infinity determined. Since the area is set, a rear side monitoring device for a vehicle can be obtained in which the monitoring area can be determined only by detecting the steering angle and without any processing work such as complicated calculation.

According to the third aspect of the invention, two white line positions are stored in advance corresponding to the steering angle of the vehicle, and the two white line positions determined by reading out the one corresponding to the detected steering angle are used. Since the monitoring area is set by the vehicle, a rear side monitoring apparatus for a vehicle can be obtained in which the monitoring area can be determined only by detecting the steering angle and without performing a complicated operation such as computation.

According to the fourth aspect of the present invention, the outer edge of the road image obtained by the imaging means is determined by image processing.
Since the monitoring area is set using two white line positions,
A rear-side monitoring device for a vehicle can be obtained in which a monitoring area can be determined by performing image processing on a small and small area and without performing a processing operation such as a complicated calculation.

According to the fifth aspect of the present invention, two white line positions where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means are known in advance, and the infinite point in the road image is also processed by image processing. It is determined by the intersection of the detected straight lines, and the inside or outside of the area surrounding the line connecting them is set as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area, and the point at infinity is also easy. In addition, since it can be accurately determined, a rear side monitoring device for a vehicle can be obtained in which the monitoring area set near the point at infinity is also somewhat accurate.

According to the sixth aspect of the present invention, two white line positions where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means are known in advance, and the point at infinity in the road image is also processed by image processing. It is determined by the convergence point of the detected optical flow, and the inside or outside of the area surrounding the line connecting them is set as the monitoring area, and it is not necessary to detect the white line itself to divide the monitoring area, and the point at infinity is also easy. In addition, since it can be accurately determined, a rear side monitoring device for a vehicle can be obtained in which the monitoring area set near the point at infinity is also somewhat accurate.

According to the seventh aspect of the present invention, two white line positions where the white lines on both sides of the own lane intersect with the outer edge of the road image obtained by the imaging means can be known in advance, and the traveled road shape in the road image is also detected. The monitoring area is defined as the monitoring area inside or outside the area surrounding the road shape from the two white line positions, and it is not necessary to detect the white line itself to divide the monitoring area, and the monitoring area can be easily and accurately determined. Since it can be determined, a rear-side monitoring device for a vehicle can be obtained in which the set monitoring area is also somewhat accurate.

According to the eighth aspect of the present invention, since the monitoring area is set by selecting the two white line positions based on the detected steering angle of the vehicle, the monitoring area close to the own vehicle is also accurate. The rear side monitoring device for a vehicle is obtained.

According to the ninth aspect of the present invention, two white line positions are stored in advance corresponding to the steering angle of the vehicle, and the two white line positions determined by reading out the position corresponding to the detected steering angle are used. The rear-side monitoring device for the vehicle that can accurately determine the monitoring area near the host vehicle only by detecting the steering angle without the need for complicated processing operations such as complicated calculations. can get.

According to the tenth aspect of the present invention, the monitoring area is set using two white line positions determined by performing image processing on the outer edge of the road image obtained by the imaging means. A rear side monitoring device for a vehicle can be obtained which can accurately determine a monitoring region close to the host vehicle only by performing image processing on the region and without processing work such as complicated calculations.

According to the eleventh aspect of the present invention, outside the area surrounded by the line connecting the two white line positions, that is,
The area including the adjacent lane adjacent to the own lane is the monitoring area, and the driver is warned when there is another vehicle approaching from the rear side of the own vehicle within the monitoring area in the detected lane change direction. It is not necessary to detect the white line itself to divide the monitoring area, and it is possible to give the necessary warning in a short processing time, so that the warning is given to the driver when the danger is detected as a result of rear side monitoring A rear side monitoring alarm device for a vehicle is obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a vehicle rear side monitoring device and a vehicle rear side monitoring alarm device of the present invention.

FIG. 2 is a block diagram showing a configuration of a rear side monitoring and warning device for a vehicle according to the present invention.

FIG. 3 is a flowchart showing an outline of an operation of the vehicle rear side monitoring and alarming device of the present invention.

FIG. 4 is a diagram showing an example of a road image captured by a video camera in the vehicular rear side monitoring and warning device of the present invention.

FIG. 5 is a diagram schematically illustrating an FOE that moves when a steering angle is changed and two white line positions where a white line intersects an outer edge of a road image.

FIG. 6 is a diagram showing a table of steering angle-infinity point data stored in a memory area of a RAM.

FIG. 7 is a diagram showing a table of steering angle-infinity point-white line position data stored in a memory area of a RAM.

FIG. 8 is a diagram illustrating a flowchart of an example of a monitoring area setting process.

FIG. 9 is a diagram illustrating an example of a method of setting a monitoring area.

FIG. 10 is a diagram showing an example of a method of determining a white line position.

FIG. 11 is a diagram showing an example of a method of estimating a road shape after traveling.

FIG. 12 is a diagram showing a monitoring area set based on a road shape estimated in the manner of FIG. 11;

FIG. 13 is a block diagram showing a configuration of a conventional rear side monitoring and warning device for a vehicle.

FIG. 14 is a diagram for explaining changes in a rear side road image obtained by the video camera 1;

FIG. 15 is a diagram showing an optical arrangement.

FIG. 16 is a conceptual diagram showing a road image of an expressway with three lanes on each side.

[Explanation of symbols]

10 imaging means (video camera) 31-1 monitoring area setting means (CPU) 31-2 optical flow detecting means (C
PU) 31-3 Line detection means (CPU) 31-4 Infinity point determination means (CPU) 31-5 Still object optical flow detection means (CPU) 31-6 Infinity point determination means (CPU) 31-7 Road shape Estimating means (CPU) 32-1 Rudder angle-infinity point storage means (RO
M) 32-2 Rudder angle-white line position storage means (RO
M) 40 warning means (warning unit) 51 steering angle detecting means (steering angle sensor) 52 turn signal detecting means (turn signal detecting switch) 53 vehicle speed detecting means

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G08G 1/16 H04N 7/18 J H04N 7/18 G06F 15/70 410

Claims (11)

[Claims] 1. An image pickup means mounted on a vehicle to obtain a road image at predetermined time intervals by imaging a road on a rear side of the vehicle, and a monitoring area corresponding to a lane of the road in the road image obtained by the image pickup means. And an optical flow for detecting an optical flow generated from another vehicle within the set monitoring area based on two consecutive road images obtained at regular intervals by the imaging means. A vehicle rear side monitoring device for monitoring a relative relationship between a host vehicle and a subsequent vehicle using the optical flow detected by the optical flow detecting unit, wherein the rudder detects a steering angle of the vehicle. The monitoring area setting means, wherein the white lines on both sides of the own lane in the road image captured by the imaging means are the outer edges of the road image obtained by the imaging means. The monitoring area is set inside or outside a region surrounded by a line connecting two intersecting white line positions and a point at infinity in a road image obtained by the imaging unit, which is determined by the steering angle of the vehicle detected by the steering angle detection unit. A rear side monitoring device for a vehicle, characterized in that: 2. The surveillance area setting means includes a steering angle-infinity point storage means which stores the infinity point in advance corresponding to a steering angle of a vehicle, and stores the infinity point in the steering angle- 2. The rear side monitoring device for a vehicle according to claim 1, wherein a value corresponding to the steering angle detected by the steering angle detection means is read from an infinity point storage means and determined. 3. The monitoring area setting unit includes a steering angle-white line position storage unit that stores the two white line positions in advance corresponding to a steering angle of a vehicle, and stores the two white line positions in the steering angle. 3. The rear side monitoring device for a vehicle according to claim 1, wherein a value corresponding to the steering angle detected by the steering angle detection means is read from a white line position storage means and determined. 4. The vehicle according to claim 1, wherein the monitoring area setting unit determines the positions of the two white lines by performing image processing on an outer edge of a road image obtained by the imaging unit. For rear side monitoring device. 5. An image pickup means mounted on a vehicle and picking up an image of a road on the rear side of the vehicle to obtain a road image at regular intervals, and a monitoring area corresponding to the lane of the road in the road image obtained by the image pickup means. And an optical flow for detecting an optical flow generated from another vehicle within the set monitoring area based on two consecutive road images obtained at regular intervals by the imaging means. A vehicle rear-side monitoring device that monitors the relative relationship between the host vehicle and another following vehicle using the optical flow detected by the optical flow detecting unit, wherein the monitoring area setting unit includes: Straight line detecting means for detecting a plurality of straight lines by performing edge processing on a road image obtained by the image pickup means; and detecting an intersection of the plurality of straight lines detected by the straight line detecting means in advance. And infinity point determination means for determining as an infinity point in the road image, wherein two white line positions where the white lines on both sides of the own lane imaged by the imaging means intersect with the outer edge of the road image obtained by the imaging means A rear side monitoring device for a vehicle, wherein the monitoring region is set within or outside a region surrounded by a line connecting the infinity point in the road image determined by the infinity point determination means. 6. An image pickup means mounted on a vehicle for picking up an image of a road on the rear side of the vehicle to obtain a road image at regular intervals, and a monitoring area corresponding to the lane of the road in the road image obtained by the image pickup means. And an optical flow for detecting an optical flow generated from another vehicle within the set monitoring area based on two consecutive road images obtained at regular intervals by the imaging means. A vehicle rear-side monitoring device that monitors the relative relationship between the host vehicle and another following vehicle using the optical flow detected by the optical flow detecting unit, wherein the monitoring area setting unit includes: A stationary object optical for detecting a plurality of optical flows generated from a stationary object in two road images that come and go at regular intervals obtained by the imaging unit A row detecting unit, and an infinity point determining unit that determines a convergence point of the optical flow detected by the stationary object optical flow detecting unit as an infinity point in the road image. Or within an area surrounded by a line connecting two white line positions where the white lines on both sides intersect with the outer edge of the road image obtained by the imaging means and the infinity point in the road image determined by the infinity point determination means or A rear side monitoring device for a vehicle, wherein the monitoring area is set outside. 7. An image pickup means mounted on a vehicle and imaging a road on a rear side of the vehicle to obtain a road image at regular intervals, and a monitoring area corresponding to a lane of the road in the road image obtained by the image pickup means. And an optical flow for detecting an optical flow generated from another vehicle within the set monitoring area based on two consecutive road images obtained at regular intervals by the imaging means. A vehicle rear side monitoring device for monitoring the relative relationship between the host vehicle and another following vehicle using the optical flow detected by the optical flow detecting unit; And a steering angle detecting means for detecting a steering angle of the vehicle, wherein the monitoring area setting means includes a past steering angle detected by the steering angle detecting means and the vehicle speed detection. With the past vehicle speed detected by the step, has a road shape estimating means for estimating the road shape that has been traveled, white lines on both sides of the own lane imaged by the imaging means and the outer edge of the road image obtained by the imaging means A rear side monitoring device for a vehicle, wherein the monitoring area is set within or outside an area surrounded by two intersecting white line positions and the estimated road shape. 8. The monitoring area setting unit, wherein the two white line positions are selected based on a steering angle of the vehicle detected by the steering angle detection unit.
The rear side monitoring device for a vehicle according to the above. 9. The monitoring area setting unit includes a steering angle-white line position storage unit that stores the two white line positions in advance corresponding to a steering angle of a vehicle, and stores the two white line positions in the steering angle. 8. The rear side monitoring device for a vehicle according to claim 7, wherein a value corresponding to the steering angle detected by the steering angle detection means is read from a white line position storage means and determined. 10. The monitoring area setting unit, wherein the two white line positions are determined by performing image processing on an outer edge of a road image obtained by the imaging unit. Rear side monitoring device for vehicles. 11. A rear side monitoring device for a vehicle according to claim 1, wherein said monitoring area is set outside said enclosed area, and a blinker for detecting an operation of said blinker and an operation direction thereof. Detecting means for driving when there is another vehicle approaching from the rear side of the own vehicle within the monitoring area in the operation direction detected by the turn signal detecting means as a result of monitoring by the vehicle rear side monitoring device; And a warning means for giving a warning to an occupant.