JP2000127849A - Rear and side monitor for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rear and side monitor for a vehicle capable of accurately and certainly detecting or presuming invasion of other vehicles in a blind spot. SOLUTION: A characteristic point extraction means 102 extracts at least one characteristic point of an image of some other running vehicle rearward or on an adjacent traffic lane from an image of a rear and side scene picked up at one point of time, while a corresponding point detection means 103 detects a corresponding point to the characteristic point from an image picked up as a frame at the next point of time. An optical flow formation means 104 forms an optical flow of the characteristic point of that other vehicle, i.e., a vector connecting the characteristic point and the corresponding point. When the optical flow of the characteristic point of the other vehicle goes and disappears out of a frame of an image plane within which an image pickup means 101 can pick up an image, an in-blind-spot inter-vehicle distance presuming means 105 presumes at least one of an inter-vehicle distance and a relative position relation between the other vehicle and its own vehicle after the disappearance of the optical flow of the characteristic point of that other vehicle, on the basis of the optical flow of the characteristic point of that other vehicle just before the disappearance thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device such as a small CCD mounted on a vehicle such as an automobile. The present invention relates to a vehicle rear side monitoring device for detecting another vehicle approaching from the rear side and notifying the driver of the approach of the other vehicle to a driver by an alarm or the like.

[0002]

2. Description of the Related Art For example, when a driver of a vehicle traveling on a road having two or more lanes on one side such as a highway changes lanes, the driver changes the lane to an adjacent lane at a higher speed. For example, when another vehicle running is catching up from the rear side, if the driver changes the lane while the driver overlooks the existence of the other vehicle, there is an extremely high risk of a major accident.

[0003] Further, even when another vehicle following the same vehicle is traveling in the same lane as the own vehicle, the other following vehicle suddenly approaches at a speed faster than the own vehicle (compared to each other at ground speed). In such a case, there is a danger that the vehicle will collide if the vehicle is suddenly braked. In this sense, it is necessary to reliably recognize a nearby vehicle. Particularly, in recent years, various types of vehicles, such as passenger cars, traveling on roads have been enhanced in both traveling speed and acceleration, and the performance has been further improved. Is more agile, and as a result, the driver overlooking the presence of another vehicle traveling around the own vehicle further increases the probability of occurrence of a dangerous condition or a major accident. .

In order to prevent such a driver from overlooking another vehicle in the vicinity, it is needless to say that the driver needs to pay more attention to the surroundings. Concentration and cognitive ability are approaching the limit that can follow the improvement of vehicle performance as described above, and accidents caused by oversight of the existence of other vehicles that occur in such a limit area Many occurred. In addition, it is generally known that human visual cognition rapidly decreases, especially as driving at high speeds,
It is expected that the problem of oversight of other vehicles in the vicinity, such as when changing lanes as described above, will become more serious as the vehicle responds to further high-speed traveling. Furthermore, particularly in the case of another vehicle approaching the host vehicle from the rear side, a blind spot is formed in a specific area diagonally behind the driver's seating position in the host vehicle, that is, in the rear side. Since the vehicle is present, especially for other vehicles entering the blind spot area, the probability of the driver overlooking is extremely high, and due to overlooking other vehicles traveling in the blind spot area,
In addition, there is a very high risk that an accident such as a collision or a collision occurs between the vehicle and the own vehicle.

[0005] Therefore, in order to prevent the occurrence of the above-mentioned accidents and dangerous situations, it is necessary not only to alert the driver to the surrounding other vehicles, but also to a person's direct recognition ability. Solves the above-mentioned danger problem by automatically and accurately recognizing the presence of another vehicle traveling around the own vehicle and transmitting (notifying) the information to the driver clearly. Techniques to be attempted have been proposed. In other words, as a conventional technique capable of recognizing another vehicle traveling in an adjacent lane or another vehicle following, for example, Japanese Patent Laid-Open No.
There is a technology of a vehicle information display device disclosed in Japanese Patent No. 9289. According to the technology disclosed in Japanese Patent Application Laid-Open No. 1-189289, the rear side of the vehicle is photographed by a camera, and the photographed image is displayed on a monitor screen, so that other vehicles traveling in the adjacent lane and The driver can recognize the following other vehicle.

However, according to such a technique,
In order for the driver to recognize the presence of another vehicle or another following vehicle traveling in the adjacent lane, the driver always looks at the image on the monitor screen and carefully looks at the image displayed on the monitor screen. It is necessary to check whether or not another vehicle is displayed on the monitor screen, but for the driver, there is a risk that the vehicle displayed on the monitor screen may be overlooked. Therefore, it is difficult to immediately determine whether or not the speed of the vehicle traveling in the adjacent lane and the speed of the following vehicle is higher than the speed of the own vehicle. In order to continue safe driving forward, It is necessary to pay close attention to the image displayed on the monitor screen, in addition to paying attention to the front of the vehicle, Note that Forces must be constantly distributed, and in some cases it is rather cumbersome for the driver to shift his / her gaze between the front and the monitor screen in order to make such a rear side safety check. ,Also,
On the contrary, there was also a problem that attention was constantly dispersed.

In view of this, a video camera is attached to the rear of the host vehicle in a rearward direction so that each point of a captured image obtained while the host vehicle is traveling converges at an infinity point or a vanishing point ( In addition to obtaining an FOE (Focus of Expansion), a feature point recognized as an image of another vehicle in the captured image is extracted, and a temporal movement of the feature point is determined by a movement vector, that is, an optical flow (hereinafter referred to as an optical flow). Is called optical flow).
Depending on whether this optical flow is diverging from the FOE or in a direction converging on the FOE, the other vehicle traveling in the adjacent lane or the following other vehicle, There have been proposed various rear-side monitoring devices for vehicles that calculate the approaching relative speed, relative distance, or relative positional relationship, and methods of monitoring the rear side of vehicles using the same (Japanese Patent Application No. Hei 5-205).
196189).

The main points of the rear side monitoring method using the conventional vehicle rear side monitoring apparatus will be briefly described with reference to FIG. FIG. 9 shows an image obtained by a monitoring camera, which is an image pickup means attached rearward to the rear of the host vehicle, that is, a rear side obtained within a frame of an image plane 1100 of an image sensor such as a CCD image sensor of the camera. It is a figure showing an example of an outline of a scene. FIG. 9 shows another vehicle 11 traveling in the next lane in which the own vehicle is traveling.
01 shows an example in which the vehicle overtakes the own vehicle.

First, in FIG. 9A, another vehicle 1101 is shown.
Are recognized and distinguished from the rear side view image obtained in the frame of the image plane 1100.

Various methods can be used as a method of recognizing the image of the other vehicle 1101. For example, the brightness of the image of the other vehicle 1101 to be recognized and the image of other roads and backgrounds (not shown) are recognized. Conventionally, it is common to use the difference to recognize a boundary between them, that is, to accurately detect a so-called edge. In order to increase the detection accuracy, edge enhancement by differential processing as preprocessing,
It goes without saying that an image processing method such as noise removal using spatial filtering may be used. Since a general tendency of image processing tends to require an enormous amount of data processing, it is desirable to simplify the processing as much as possible. As a method of the boundary recognition, for example, various polygon approximation methods such as a Freeman method, a Sklansky method, and a distance division method can be used. After the recognition of the boundary (edge) of the image of the other vehicle 1101 in this manner, the boundary or an area included in the boundary is recognized, and a predetermined predetermined value is selected from the recognition. Feature point A that satisfies the above condition is extracted.

[0011] In FIG.
An example is shown in which the center of the edge 1102 at the position closest to the FOE, that is, the position farthest from the host vehicle, of the boundary (edge) of the image 01 is extracted. Then, in the frame at the next time point after the frame at which the feature point A is extracted, the corresponding point corresponding to the feature point A is defined on a straight line connecting the FOE and the feature point A in FIG. Explore.
In this example, point A 'in FIG. 9B is detected as a corresponding point. Then, a vector connecting the point A ′ extracted from the point A extracted in the above-mentioned frame becomes an optical flow. In the example of FIG. 9, the optical flow is FOE.
Therefore, the other vehicle traveling in the adjacent lane is approaching the own vehicle, and the magnitude of the optical flow at this time (that is, the absolute value of the vector) The value at this time is other vehicle 1
The larger the speed at which the vehicle 101 approaches the own vehicle (the camera thereof) and the closer the distance between the two vehicles becomes, the larger the speed becomes. Therefore, the magnitude of the optical flow and the high danger between the two vehicles at that time Will be approximately proportional.

The other vehicle 1 thus obtained
Based on the optical flow information of the feature point 101, it is determined whether or not the movement of the other vehicle 1101 is highly dangerous to the own vehicle. If it is determined that the danger is high, and the own vehicle activates a turn signal to change lanes at that time, a warning that changing the lane at that time is high risk is given. To the driver with an alarm sound, such as an alarm sound, to prevent the occurrence of accidents such as collisions or contact with other vehicles, such as when changing lanes as described above. It can be said that.

It should be noted that reference numerals 1205, 1 in FIGS.
Reference numerals 206 and 1207 denote white lines applied on the road 1202 to distinguish lanes on the road 1202.

[0014]

However, as shown in FIG. 7, for example, the other vehicle 1101 is out of the image-capable area of the own vehicle 1103 by the image-capturing means.
In the case where the vehicle has entered a so-called blind spot area 1200 in FIG.
In such a case, it is impossible to detect the presence of another vehicle 1101 in the above-described conventional vehicle rear-side monitoring device in such a case.

Further, the blind spot area 1200 in the image pickup means 1104 is almost (or more than) a blind spot area in which it is difficult to recognize the presence of the other vehicle 1101 from the driver's seating position. overlapping.

Furthermore, such a blind spot area 1
200 indicates that the vehicle 1103 is in the left lane 1 on the road 1202
When the lane is changed to the right lane 1204 while traveling on the road 203, the area where the own vehicle 1103 is likely to move, that is, the area 1201 in the length direction of the own vehicle 1103 in the right lane 1204 is centered. Such a blind spot area 12 is overlapped with the area before and after that.
Changing the lane to the right lane 1204 of the own vehicle 1103 in a state where another vehicle 1101 has intruded into 00 has a problem that it is extremely dangerous which may lead to a major accident.

Therefore, in order to solve the problem caused by the blind spot outside the image-capturable area of the image-capturing unit 1104, the size of the image-capable area of the image-capturing unit 1104, in other words, the image-capturable area of the image-capturing unit 1104 In order to make the angle of the range θ as wide as possible, for example, it is considered to increase the diameter of a lens used in the camera. In any case, the angle of the imageable area of the imaging unit 1104 is considered. θ is at most about θ ≦ 100 degrees, and if the angle θ of the image-capturable area is excessively widened too much, distortion or aberration or the like is greatly generated in a captured image, and the correct luminance or shape is not obtained. There is another problem that images cannot be obtained or even if they are to be corrected, the data processing becomes extremely complicated. Inevitably. Also, no matter how wide the angle θ of the image-capturable area of the image-capturing unit 1104 is, it is theoretically impossible to make it 180 degrees or more. Region 12 in the longitudinal direction of the own vehicle 1103
In the case where another vehicle 1101 has intruded into 01, the state is still undetectable, even though the state is most difficult to recognize and the risk is the highest, and as a result, the most dangerous state is also detected. There was a problem that you can not.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and the present invention is applied to a case where another vehicle which is in the most dangerous state with respect to the own vehicle enters another blind spot area. It is an object of the present invention to provide a vehicle rear side monitoring device capable of accurately and surely detecting or estimating that the vehicle has entered the blind spot area.

[0019]

A vehicle rear side monitoring apparatus according to the present invention firstly captures a rear side view from a running own vehicle by an image pickup means 101, and detects two frames which are in front of and behind a predetermined time. In the vehicle rear side monitoring device that detects the temporal movement of the corresponding point corresponding to each other image as an optical flow and monitors the approaching state of another vehicle traveling behind or in the adjacent lane to the own vehicle, at a certain time A feature point extraction unit 102 that extracts, as a feature point, at least one point of an image of another vehicle traveling in the rear or adjacent lane from the captured image of the rear view, and a frame at a time point next to the time point. A corresponding point detecting means 103 for detecting a corresponding point corresponding to the feature point from the captured image; and a vector connecting the feature point and the corresponding point as an optical flow of the feature point of the other vehicle. When the optical flow forming means 104 and the optical flow of the feature point of the other vehicle disappear from the frame of the image plane that can be imaged by the imaging means 101 outwardly and disappear, Based on the optical flow of the feature point of the other vehicle, at least one of the inter-vehicle distance and the relative positional relationship between the other vehicle and the host vehicle after the point at which the optical flow of the feature point of the other vehicle disappears. Blind spot inter-vehicle distance estimating means 10 for estimating one of them
5 is provided.

That is, the fact that another vehicle has entered the blind spot area (of the image pickup means) of the own vehicle means that the optical flow of the characteristic point of the other vehicle on the image plane of the image pickup means moves outward from the frame of the image plane. It corresponds to having gone out of the frame.

Therefore, when the optical flow of the feature point of the other vehicle disappears from the frame of the image plane which can be imaged by the image pickup means 101 outwardly and disappears, the means for estimating the inter-vehicle distance in the blind spot is used. 105
Is determined that the other vehicle has entered the blind spot area of the imaging means of the own vehicle from the time when the feature point disappears, and the position of the feature point of the other vehicle in the image plane of the optical flow immediately before the disappearance is determined. The relative position of the other vehicle with respect to the own vehicle at the time of the disappearance can be calculated based on the coordinates, and based on the length of the optical flow at the time of the disappearance, the other vehicle at the time of the disappearance can be calculated. The relative speed of the own vehicle with respect to the own vehicle is calculated, and based on this relative speed, the inter-vehicle distance and the relative position of the other vehicle with respect to the own vehicle thereafter (that is, after the other vehicle starts to enter the blind spot area) are calculated. , For example, every second.

Further, the data of the inter-vehicle distance and the relative position of the other vehicle with respect to the own vehicle obtained as a result of the estimation obtained in this way are displayed on a display screen such as a display means 106 using a liquid crystal display panel, for example. By displaying and outputting the information, it is possible for the driver to reliably recognize the presence of another vehicle which is hardly visually recognized by entering the blind spot area around the own vehicle.

The above-mentioned blind spot inter-vehicle distance estimating means 10
5 determines the relative position of the other vehicle with respect to the own vehicle at the time immediately before the disappearance based on the coordinates of the optical flow immediately before the disappearance in the image plane, and determines the relative position at this time. At least one or both of the inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle after the disappearance as the starting point may be estimated.

The rear side monitoring device for a vehicle according to the present invention
In the vehicle rear side monitoring device according to the first aspect, the blind spot inter-vehicle distance estimating means 105 includes an optical flow of a characteristic point of the other vehicle within a frame of an image plane that can be imaged by the imaging means 101. When the optical flow reaches a predetermined area of the peripheral portion, it is considered that the optical flow disappears at the time of the next frame, and the characteristic point of the other vehicle immediately before the optical flow at the time of the arrival disappears. A blind spot for estimating at least one of an inter-vehicle distance and a relative positional relationship between the other vehicle and the host vehicle after the arrival time or the time point of the next frame after the arrival time, using the optical flow of It is characterized by the inner vehicle distance estimating means 105.

That is, when another vehicle catches up with the own vehicle and enters the blind spot area of the own vehicle while the own vehicle is traveling in the forward direction, the image is generally taken in accordance with the state. After the optical flow reaches a predetermined area defined as a valid area from the peripheral edge to the outermost frame at the outermost end of the imageable range in the frame of the image plane of the means, The optical flow should disappear at the time of the frame.

In other words, in other words, after an optical flow is extracted at any position within the frame of the image plane, the optical flow moves within the image plane, and a predetermined margin of the image plane is When the optical frame comes to (the position of the imaging cell of) the part or the outermost end, the optical flow of the next frame is moved out of the frame of the image plane to the outside as described in the first description. It can be regarded as disappearing.

Here, the optical flow moves in the image plane and reaches the peripheral portion once, but returns to the center of the image plane again at the next frame. , But the probability is very small. Therefore, if such a special case is considered as an exceptional event, the optical flow moves in the image plane and is located in a predetermined area (the position of the imaging cell) in the periphery of the image plane. When it comes, it can be considered that the optical flow disappears at the time of the next frame so that it goes out of the frame of the image plane to the outside as described in the first description above. It is.

Thirdly, the vehicle rear side monitoring device according to the present invention is the vehicle rear side monitoring device according to the first or second aspect, wherein the other vehicle estimated by the blind spot inter-vehicle distance estimating means 105 is used. Based on the inter-vehicle distance or relative positional relationship between the vehicle and the own vehicle, a risk determining unit 107 that determines the degree of risk of contact or collision with the other vehicle with respect to the own vehicle, It is further characterized by comprising:

That is, based on the inter-vehicle distance or the relative positional relationship between the other vehicle and the own vehicle estimated by the blind spot inter-vehicle distance estimating means 105, the vehicle with respect to the own vehicle at every moment is determined. The degree of risk of contact or collision with the other vehicle can be determined by the degree of risk determination means 107. And furthermore, by displaying it to the driver to warn or sounding an alarm buzzer,
The danger of contact and collision between vehicles as described above can be avoided beforehand.

Fourth, the rear side monitoring device for a vehicle according to the present invention provides a vehicle-to-vehicle distance or relative positional relationship between the other vehicle and the host vehicle estimated by the blind spot inter-vehicle distance estimation means 105. When the vehicle is in a predetermined range as a state in which there is a risk of contact or collision with the other vehicle, the vehicle is installed in the vehicle to display an intention when changing lanes. When an input to turn on the turn signal indicator 108 is made, an alarm generating means 109 is further provided which issues an alarm indicating the danger at least one of auditory information and visual information. It is characterized by doing.

That is, if another vehicle enters the blind spot area of the own vehicle as described above and the own vehicle executes a movement such as a lane change, the own vehicle may collide with the other vehicle. Even if a serious accident could occur,
According to the present invention, when another vehicle is in the blind spot area of the own vehicle, an input indicating that the own vehicle turns on the direction indicator 108 to execute a movement such as a lane change is made. In this case, the alarm generating means 109 issues an alarm indicating the danger as auditory information or visual information. Thus, when another vehicle has entered the blind spot area of the own vehicle, it is guessed that the other vehicle has entered the blind spot area. By issuing an alarm, it is possible to solve a problem that a serious accident occurs due to a collision between the own vehicle and another vehicle.

Fifthly, the vehicle rear side monitoring apparatus according to the present invention is the vehicle rear side monitoring apparatus according to any one of the first to fourth aspects, wherein the blind spot inter-vehicle distance estimation means 105 is provided.
The optical flow of the characteristic point of the other vehicle at the time of reaching a predetermined area of the peripheral portion in the frame of the image plane that can be imaged by the imaging means 101 is shifted in the horizontal direction or upward in the rear side view. In the case of an optical flow having a corresponding directional component, the inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle after the arrival time or the time point of the next frame after the arrival time. The optical flow of the characteristic point of the other vehicle at the time when the predetermined point of the peripheral portion in the frame of the image plane that can be imaged by the imaging unit 101 is reached without performing the estimation is less than the horizontal direction in the rear side view. With a directional component corresponding to the downward direction, only when there is an optical flow of a feature point of another vehicle entering the blind spot of the host vehicle, A blind spot inter-vehicle distance estimating means 105 for estimating at least one of an inter-vehicle distance and a relative positional relationship between the other vehicle and the host vehicle after the vehicle arrives at or after the time of a frame next to the time. It is characterized by being.

That is, as shown in FIG. 8, for example, when the own vehicle and the other vehicles 1301, 1302, and 1303 are running on a curved road having a relatively small radius of curvature, the vehicle is more than the own vehicle. Other vehicle 1 running at low speed
When the image is taken on the image plane 1100 of the image pickup means 101 of the own vehicle, the image plane 301 is moved in a direction farther away from the own vehicle.
Will go out of the frame. However, the other vehicle 1301 moving away in the opposite direction may be determined as having entered the blind spot area of the own vehicle. Alternatively, as in the case of another vehicle 1302, the vehicle may leave the branch of the road in another direction.

In order to prevent erroneous determination in such a case, according to the present invention, the blind spot inter-vehicle distance estimating means 105 is provided.
Is the characteristic point of the other vehicle entering the blind spot of the own vehicle, having a directional component corresponding to a direction in which the optical flow of the characteristic point of the other vehicle immediately before disappearance is less than the horizontal direction or downward in the rear view. Only when it is the optical flow of, at least one of the inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle after the arrival time or the time of the next frame after the arrival time In other cases, that is, while the optical flow of the feature point of the other vehicle has a component in a direction away from the own vehicle (that is, a direction in which the horizontal direction or the upward direction in the rear side view is used). When the vehicle goes out of the frame of the image plane 1100, the other vehicle 130
Reference numeral 1,1302 does not judge that the vehicle has entered the blind spot area of the vehicle. As a result, only when the vehicle really enters the blind spot area as in the case of another vehicle 1303, it can be accurately determined, and erroneous determination can be prevented.

According to a sixth aspect of the present invention, there is provided a vehicle rear side monitoring apparatus according to any one of the first to fifth aspects, wherein the optical flow of characteristic points of the other vehicle is the same as that of the first aspect. When the image plane 101 is framed outward from the frame of the image plane that can be imaged by the imaging unit 101 and disappears, when an operation for changing lanes is performed within a predetermined time after the disappearance, a lateral collision occurs. Alarm generating means 10 for issuing an alarm indicating that there is a risk of occurrence of at least one of auditory information and visual information
9 'is further provided.

That is, the optical flow of the feature point of the other vehicle is converted into an image plane
When the optical flow disappears from the frame 00 outward from the frame 00, a predetermined time such as a time required for general overtaking on a highway, for example, three seconds from the time when the optical flow disappears from the edge of the screen. The time can be considered that the nearby vehicle is traveling in the blind spot area beside the own vehicle. Therefore, if an intention to change lanes is indicated by performing a lane change operation such as a turn signal within a certain period of time after disappearance, there is a high risk of a lateral collision occurring. By issuing the warning of the above, it is possible to estimate the inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle without inferring the inter-vehicle distance and the relative positional relationship between the other vehicle 1101 (FIG. 3) and 1303 (FIG. 8). For the intruding vehicle, the second alarm generation means 109 'can easily alarm the danger.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle rear side monitoring apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the main part.

The rear side monitoring device for a vehicle captures a rear side view from a running vehicle by the image capturing means 101,
A vehicle for monitoring the relative position of another vehicle traveling in the rear or adjacent lane with respect to the host vehicle by detecting the temporal movement of the corresponding point between two images preceding and following the predetermined time as an optical flow. A side monitoring device,
More specifically, a feature point extracting unit 1 that extracts, as a feature point, at least one point of another vehicle traveling in the rear or adjacent lane from the image of the rear view taken at a certain point in time.
02, a corresponding point detecting means 103 for detecting a corresponding point corresponding to the feature point from an image captured as a frame at a time point next to the time point, and a vector connecting the feature point and the corresponding point to the other. The optical flow forming means 104 which forms the optical flow of the characteristic point of the vehicle, and the optical flow of the characteristic point of the other vehicle are formed by the imaging means 1.
01 and disappears from the frame of the image plane which can be imaged outward and disappears, based on the optical flows of the feature points of the other vehicle immediately before the disappearance, based on the optical flows of the feature points of the other vehicle. A blind spot inter-vehicle distance estimating means 105 for estimating an inter-vehicle distance and a relative positional relationship between the other vehicle and the host vehicle after the disappearance of the vehicle.

The blind spot inter-vehicle distance estimating means 105
More specifically, when the optical flow of the feature point of the other vehicle reaches a predetermined area of the peripheral portion in the frame of the image plane that can be imaged by the imaging unit 101, the optical flow is changed to the next frame. At the time point, it is regarded as disappearing, and the optical flow at the time of arrival is used as the optical flow of the characteristic point of the other vehicle immediately before the disappearance. The inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle after the time point are estimated.

If the above-mentioned predetermined region of the peripheral portion in the frame of the image plane is taken too inward from the frame of the image plane, the point of time when the feature point is deemed to be lost is too early. On the other hand, if the space of the predetermined area around the image plane is too small due to being too close to the frame of the image plane, the disappearance of the feature point cannot be detected.

This is because, if the space in the predetermined area of the peripheral portion is too small, for example, when the speed of another vehicle is high, the feature points (corresponding points) detected for each frame of the imaging timing pass through the space. This is because the probability that the disappearance of the feature point cannot be detected in a predetermined area of the peripheral portion increases.

Therefore, it is desirable to set the peripheral area as described above in consideration of such conditions.

The above-described blind spot inter-vehicle distance estimating means 10
The data of the inter-vehicle distance and the relative position of the other vehicle with respect to the own vehicle estimated in step 5 are displayed on a display screen of a display means 106 using a liquid crystal display panel, for example, and output to the driver. This makes it possible to reliably recognize the presence of another vehicle that is hardly visually recognized by entering the blind spot area around the vehicle.

Further, based on the inter-vehicle distance or relative positional relationship between the other vehicle and the own vehicle estimated by the inter-vehicle distance in blind spot estimation means 105, the other vehicle with respect to the own vehicle is A risk determining means for determining a degree of risk of contact or collision with the vehicle; and a distance between the other vehicle and the own vehicle estimated by the blind distance-to-vehicle distance estimating means 105; Based on the positional relationship, the risk determining means 107 determines the degree of danger of contact or collision with the other vehicle with respect to the own vehicle at each moment, and based on the result, the danger is determined. When the level exceeds a certain level, the alarm buzzer 110 sounds to warn the driver of the danger of contact between vehicles and collision.

For the method of determining the degree of danger, a criterion used by a conventional general rear side monitoring device for a vehicle may be used, or, in particular, other vehicles may determine the blind spot of their own vehicle. A new criterion for the degree of danger when entering the area 1200 may be created.

For example, another vehicle 110 as shown in FIG.
1 is in the blind spot of the host vehicle 1103, the host vehicle 1101 is in a state where the host vehicle 1101 is partially in the longitudinal zone 1201 of the host vehicle 1103. If the vehicle 1103 changes lanes, the risk of collision between the two vehicles is considered to be particularly high. Therefore, even a part of the other vehicle 1101 is included in the region 1201 in the longitudinal direction of the vehicle 1103. The state may be used as a criterion for determining the degree of danger.

The above-mentioned blind spot inter-vehicle distance estimating means 10
5, the inter-vehicle distance or the relative positional relationship between the other vehicle and the own vehicle is within a range predetermined as a state in which the own vehicle has a risk of contact or collision with the other vehicle. When there is an input to turn on the turn signal indicator 108 installed in the own vehicle in order to indicate the intention when changing lanes,
The apparatus further includes an alarm generation unit 109 that issues an alarm indicating the danger as auditory information or visual information.

As shown in FIG.
If the own vehicle 1103 performs a movement such as changing lanes while the other vehicle 1101 is intruding into the blind spot area 1200 of No. 3, the own vehicle 1103 and the other vehicle 1101 collide with each other, which is extremely large. Since even an accident may occur, such a blind spot area 1200 of the host vehicle 1103 may be used.
Own vehicle 1 when another vehicle 1101 is intruding into
If the user inputs an instruction to turn on the direction indicator 108 in order to execute a movement such as a lane change, the alarm generating means 109 sounds the alarm buzzer 110 to generate an alarm indicating the danger. It emits audible information to warn the driver of the danger.

Further, means 1 for estimating the distance between vehicles in a blind spot
05 is a direction in which the optical flow of the characteristic point of the other vehicle at the time when the predetermined area of the peripheral portion in the frame of the image plane that can be imaged by the imaging means 101 is reached is shifted from the horizontal direction to the upward direction in the rear view. In the case of an optical flow having a directional component corresponding to the distance between the other vehicle and the own vehicle after the arrival time or the time of the next frame after the arrival time, the inter-vehicle distance and the relative positional relationship Do not make guesses.

Then, the blind spot inter-vehicle distance estimating means 10
5 is an optical flow of a feature point of the other vehicle at a time when a predetermined area of a peripheral portion in a frame of an image plane that can be imaged by the imaging unit 101 is reached is less than or lower than a horizontal direction in the rear side view. Only when it is an optical flow of a feature point of another vehicle entering the blind spot of the own vehicle having a direction component corresponding to the direction, the time after the arrival or the time of the next frame after the time At least one of the inter-vehicle distance and the relative positional relationship between the other vehicle and the host vehicle is estimated.

Next, the function and operation of each of the above means will be described in detail. The image pickup means 101 is an image pickup device such as an image pickup camera using an image pickup device such as a CCD image pickup device, and is installed at the rearmost portion of the vehicle 1103 as shown in FIG. The rear side view of the region over θ is imaged.

FIG. 3 is a diagram showing an example of an image formed on the image plane (described later) of the image pickup means 101 via the lens system in the state as shown in FIG. In FIG. 3, the same parts as those in FIGS. 8 and 9 are denoted by the same reference numerals.

From the image formed on such an image plane (described later), the feature point extracting means 102 calculates the luminance difference between the image of the other vehicle 1101 and the image of other roads and backgrounds (not shown). Utilize and recognize the boundaries between them. That is, a so-called edge is detected.

FIG. 4 shows an example of an edge detected from an image as shown in FIG. In order to increase the detection accuracy, an image processing method such as edge enhancement by differential processing or noise removal using spatial filtering may be used as preprocessing.

Further, since a general tendency of image processing tends to require an enormous amount of data processing, it is needless to say that it is desirable to simplify the processing as much as possible. A conventional method can be suitably used for such image processing itself.

After the boundary (edge) of the image of the other vehicle 1101 is obtained in this way, the boundary or an area included in the boundary is recognized, and a predetermined area is determined from the boundary. A feature point A that meets the predetermined condition is extracted.

That is, the feature point extracting means 102 extracts a feature point A that satisfies a predetermined condition from the edge 911 of the other vehicle 1101 in FIG.

The predetermined condition for this extraction is, for example, to select and extract the coordinates of one point which is the rearmost side in the traveling direction of the other vehicle 1101 among the coordinates of the edge 911 on the image plane 1100. Well,
Alternatively, the leading one point in the traveling direction of the other vehicle 1101 may be selected and extracted.

However, for these two examples,
When the coordinates of one rearmost point are selected and extracted as the feature point A, the feature point A is set only after the entire vehicle body of the other vehicle 1101 has completely entered the blind spot area 1200 to the rear end. Although the presence of such another vehicle 1101 cannot be detected, the movement can be reliably detected when the other vehicle 1101 has completely entered the blind spot area 1200. On the other hand, when the coordinates of the top one point are selected and extracted as the feature point A, the feature point A may be a part of the front end of the body of the other vehicle 1101 if it enters the blind spot area 1200. Since the movement of the vehicle 1101 is detected, it can be detected earlier. However, when the traveling speed of the other vehicle 1101 is changing little by little, a disturbance error tends to occur. It is also conceivable.

Therefore, taking such matters into consideration,
Needless to say, a rule for extracting the feature point A may be set.

Alternatively, other vehicle 1101 as feature point A
The center point of the edge closest to the FOE described later, that is, the center point of the edge farthest from the host vehicle, may be extracted.

In parallel with or before or after extracting the characteristic point A of the other vehicle 1101, the characteristic point extracting means 102 detects the FOE 1208 by a FOE detection unit (not shown) formed therein. .

The detection of the FOE 1208 is performed by the imaging means 1
After converting the image formed by 01 into an image signal,
The image signal is temporarily stored in the frame memory. Then, based on this image signal, the FOE detection unit detects a point at infinity, that is, the FOE 1208, from two temporally continuous images.

At this time, a high-pass filter (HPF) is used to form an edge 911 from the image signal based on the image signal of one frame past read from the frame memory. Pass only the components. That is, in other words, a signal corresponding to the image of the edge 911 as shown in FIG. 4 may be formed by differentiating the image signal.

When the FOE 1208 and the feature point A have been extracted in this way, based on them, the corresponding point detecting means 103 determines that the image is taken as the next frame of the image by the imaging period Δt from the time when the image was captured. A corresponding point A corresponding to the feature point A is selected from an image of the next frame captured later.
'Is detected. At this time, the search for the corresponding point A '
What is necessary is just to search on the half line which passes through and FOE1208.

Subsequently, the optical flow forming means 10
4 forms an optical flow 500 by taking a vector from the feature point A to the corresponding point A '.

Thus, the feature point A of the other vehicle 1101 is extracted, the corresponding point A 'corresponding to the feature point A is detected in the image of the frame at the next time point, and the vector connecting the feature point A to the corresponding point A' is obtained. And the optical flow 500 is formed, and when the image of the next frame is captured, the previous corresponding point A ′ is used as the feature point A ′ instead of the previous feature point A, and the next corresponding point is used. , The corresponding point (A ′) ′ in the image of the frame at the point of time, that is, the corresponding point (A ′) ′ corresponding to the feature point A ′ of the previous frame is detected. Such processing,
The optical flow 500 can be obtained moment by moment by repeating every time a frame of an image is captured one by one at each imaging timing.

This optical flow 500 is
The direction and the absolute value of the relative position of the other vehicle 1101 change with the change of the relative position of the other vehicle 1101 with the change of the change with time. If the speed of the own vehicle 1103 is higher than that of the own vehicle 1103, the other vehicle 1101 catches up from the rear side, and eventually becomes a state as shown in FIG.

That is, the light enters the position outside the frame of the image plane 1100, that is, the blind spot area 1200. Then, the last part of the real vehicle 1101 corresponding to the extracted feature point A also deviates from the imageable area (θ) corresponding to the frame of the image plane 1100. Other vehicles 11
01 cannot be recognized.

Therefore, in the vehicular rear side monitoring apparatus according to the present invention, the optical flow 500 at the characteristic point A of the other vehicle 1101 is framed outward from the frame of the image plane 1100 which can be imaged by the imaging means 101. When the vehicle disappears, the vehicle distance estimation means 10 in the blind spot
5 is the other vehicle 11 based on the optical flow 500 of the characteristic point A of the other vehicle 1101 immediately before disappearance.
The inter-vehicle distance L and the relative position P (X, Y, Z) between the other vehicle 1101 and the host vehicle 1103 after the point at which the optical flow 500 of the 01 characteristic point A disappears are estimated.

If it is estimated that the other vehicle 1101 is located at a relatively dangerous position such as the area zone 1201, for example, the risk determining means 107 determines whether or not the other vehicle 1101 is located at a relatively dangerous position. Then turn signal 10
If the lighting instruction of No. 8 is inputted, the alarm generating means 1
09 is determined to be dangerous, and the buzzer 11
By alerting the driver with 0 or the like, it is possible to avoid the danger when another vehicle 1101 enters the blind spot area 1200 of the own vehicle 1103.

Next, the function and operation of the blind spot inter-vehicle distance estimating means 105 for estimating the movement of the other vehicle 1101 when the other vehicle 1101 enters the blind spot area 1200 of the own vehicle 1103 will be further described. This will be described in detail.

As shown in FIG. 3 and FIG.
Comes to catch up with the own vehicle 1103 and eventually the other vehicle 110
1 (an actual vehicle 1101 instead of an image) enters the blind spot area 1200 of the imaging unit 101.

Then, at this time, the feature point A which is one point of the last image (or, in other words, the corresponding points A ', (A') ', ((A') ')' corresponding to the feature point A one after another). ... However, here, these are referred to as feature points A. The same applies hereinafter) also goes out of the frame of the image plane 1100, and the feature point A disappears, but immediately before the disappearance. Using the optical flow 501 formed at the time of one frame, the blind spot inter-vehicle distance estimation means 105
Then, the movement of the other vehicle 1101 in a state where imaging to recognition by the imaging unit 101 is not possible is estimated.

That is, the 1 immediately before the feature point A disappears.
Of the optical flow 501 formed at the time of the top
Estimating the movement of another vehicle 1101 immediately after the feature point A has disappeared based on the coordinates (position) and length (that is, the absolute value of the optical flow 501 as a vector) on the image plane 1100. Can be.

Then, based on such an optical flow 501, another vehicle 1 after the characteristic point A has disappeared.
The function and operation of estimating the inter-vehicle distance and the relative position between the vehicle 101 and the host vehicle 1103 will be described in further detail with reference to FIG.

FIG. 5 shows a feature point A, an optical flow 500 and a road 1 on the image plane 1100.
It is a figure which shows typically the relationship with the position P and P 'of the real other vehicle 1101 on 202. FIG. In FIG. 5, reference numeral 502 denotes a lens system of the camera of the imaging unit 101, P denotes a traveling position of another vehicle 1101 at a certain time; P (X, Y,
Z) and P ′ are the relative position of the other vehicle 1101 at the time when the next frame is imaged, that is, after a period Δt,
A is a point formed on the image plane 1100 corresponding to the point P, A ′ is a point formed on the image plane 1100 corresponding to the point P ′, and f is a lens system 5.
02 to the image plane 1100.
In order to simplify the explanation, the coordinate axis Z is taken parallel to the traveling direction of the other vehicle 1101 in FIG. 5, and the image plane 1100 is arranged to intersect perpendicularly with the coordinate axis Z. It was taken.

When considering geometrically based on FIG. 5, the following relational expression is obtained. That is, x = f · X / Z (1) X ′ = {(Δx / Δt) · Z + x · Z ′} / f (2) If u = Δx / Δt, then: (3) Z = (f)・ X′−xZ ′) / u (4)

Here, since Z ′ is the relative speed between the other vehicle 1101 and the own vehicle 1103 running in the adjacent lane, if this is Z ′ = − α (5), the above (4) The equation is as follows: Z = (f × X ′ + xα) / u (6)

Accordingly, the component of the optical flow 501 in the x direction (that is, Δx / Δt = u) is as follows: u = (f × X ′ + xα) / Z (7)

The y-direction component of the optical flow 501 (ie, Δy / Δt = v) is also substantially the same as above, and v = (fY ′ + yα) / Z (8) The calculation formula is obtained.

By the way, the other vehicle 1101 generally catches up with the own vehicle 1103 while traveling straight in the adjacent lane 1204 in most cases. That is, the direction of the movement is almost parallel to the Z-axis, and the movement in the X-axis direction, that is, the lateral direction is, for example, the case where the vehicle 1101 changes lanes to the left lane 1203 or the meandering due to special circumstances. In any case, the speed of such movement in the X-axis direction, that is, the lateral direction, is much smaller than the original traveling speed, that is, the speed in the Z-axis direction. In some cases, the component in the X-axis direction of the optical flow 501 of the vehicle 1101 other than the direction may be ignored or substantially ignored. In particular, for example, when the other vehicle 1101 moves to the right in the lateral direction in FIG.
101 intrudes more aggressively into the blind spot area 1200 of the imaging means 101, but at the same time, the other vehicle 1101 moves in a direction further away from the own vehicle 1103. In contrast to the situation where the technique according to the present invention is required, the vehicle heads in a direction in which the risk of contact or collision with the vehicle 1103 is reduced. Accordingly, in such a point, the technique according to the present invention has described a case where the initial value of the X-axis direction component of the speed vector of the other vehicle 1101, that is, the initial value of the lateral direction is not estimated. Needless to say, it is also possible to guess.

Needless to say, the movement of the other vehicle 1101 in the Y-axis direction, that is, the movement in the height direction, need not be taken into consideration, as a matter of course.

For the reasons described above, the X-axis direction and the Y-axis direction
The movement of the other vehicle 1101 in the axial direction may be omitted without consideration. Therefore, in the above equations (7) and (8), X ′ = 0, Y ′ = 0
Are respectively substituted, u = x · α / Z (9) v = y · α / Z (10) Such a simple relational expression is obtained.

Further, another vehicle 1101 that has caught up with the own vehicle 1103 enters the blind spot area 1200 of the imaging means 101, and eventually the blind spot area 12
00 and disappears from the imaging area of the imaging means 101, but such a blind spot area 1200
Vehicle 11 at the time when other vehicle 1101 enters
The position of 01 can be determined by the blind spot inter-vehicle distance estimating means 105 as described above.

That is, taking the state shown in FIGS. 2 to 4 as an example, the other vehicle 1101
When the vehicle enters the blind spot area 1200 and eventually the rear end of the other vehicle 1101 completely enters the blind spot area 1200, the image of the other vehicle 1101 completely disappears from the imaging area of the imaging unit 101. However, the image plane 11 of the feature point A (corresponding point A ′ in FIG. 5) in the image captured one frame before that is
The coordinates (x, y) at 00 are read and the (x, y) is read.
y) and the geometrical positional relationship based on the viewing angle θ and the road surface width W of the imaging area of the imaging means 101, and first the position P ′ (X,
Y, Z), that is, Z, that is, the inter-vehicle distance L1 as shown in FIG. 2 is detected.

More specifically, the coordinates (x, y) of the point of occurrence of the optical flow that occurred immediately before the image plane disappeared from the left and right edges of the image plane were generated at the positions of the left and right edges of the image plane. And In other words, it is assumed that the error occurs at the end of the angle of view of the horizontal angle of view θ (of the CCD camera) of the imaging unit 101. However, at this time, it is assumed that the own vehicle and the approaching vehicle are respectively traveling in the center of the traveling lane. Since the road surface width W on an expressway is generally standardized to a constant value (for example, 3.5 m), the horizontal field angle θ and the road surface width W, which are fixed and predetermined values, are used. And L1 = W / tan (.theta. / 2) (13)
L1 can be obtained by the following calculation. FIG.
From (θ / 2) = tan for A ′ (x, y)
(Θ / 2) is obtained as ⁻¹ (x / f), and this (θ / 2)
May be substituted into equation (13) to determine L1.

Further, the inter-vehicle distance detected as described above; L1 = Z, and the optical flow (u, v) generated at the coordinates (x, y) immediately before disappearing from the left and right edges of the image plane to the outside. By the above equation (9) and (10)
Substitute in an expression. Then, when further deformed, α = u · L1 / x (11) α = v · L1 / y (12) As a result, the corresponding point finally corresponding to the feature point A according to FIG. Based on the size of the optical flow 501 immediately before the disappearance of A ′ and the coordinates (x, y) of the corresponding point A ′ on the image plane 1100 in the frame immediately before the disappearance of the inter-vehicle distance, L1 can be obtained, and the magnitude α of the relative speed of the other vehicle 1101 to the own vehicle 1103 can be obtained.

Further, according to the present invention, the size of the optical flow 501 immediately before the disappearance and the coordinates A '() on the image plane 1100 of the feature point A in the frame immediately before the optical flow 501 disappears. x, y), the other vehicle 1 after the optical flow 501 of the feature point A disappears from the image plane 1100.
The movement of the vehicle 101 is estimated by the blind spot inter-vehicle distance estimating means 105.

That is, the size of the optical flow 501 immediately before the optical flow 501 disappears as described above, and the coordinates A ′ (x, y) on the image plane 1100 of the feature point A in the frame at that time. And detect.

Then, even after the optical flow 501 disappears, the other vehicle 1101 keeps the optical flow 5
Even if it is assumed that the vehicle continues running at the speed detected when 01 disappears, it should be possible to make an almost accurate estimation. The reason that the other vehicle 1101 is in the blind spot area 1200 of the own vehicle 1103 and is in a high risk state is that the distance between the other vehicle 1101 and the own vehicle 1103 is not so large in most cases. . In other words, for example, in FIG. 2, between the time when the other vehicle 1101 enters the blind spot area 1200 and the time when the other vehicle 1101 also passes the longitudinal zone 1201 in the longitudinal direction of the own vehicle 1103 and exits in front of the own vehicle 1103, usually, It is unlikely that the speed of the other vehicle 1101 will significantly change, and acceleration or deceleration during passing or overtaking at most is considered to be to some extent.

Therefore, the movement of the other vehicle 1101 during that time is determined by the relative speed α immediately before the optical flow 501 disappears and the position P ′ of the other vehicle 1101 at that time.
Using (X, Y, Z) as initial values, it is assumed that the relative speed α of the other vehicle 1101 thereafter is maintained at a constant speed, and the position of the other vehicle 1101 is the aforementioned relative speed. Assuming that the vehicle is proceeding straight along the Z-axis direction at α, the traveling state of the other vehicle 1101 can be estimated.

That is, every time a predetermined period ΔT arrives so as to periodically perform the estimation process, the blind spot inter-vehicle distance estimation means 105 uses the above relative speed α to obtain ΔL = α · Δ
T is calculated, and the value of ΔL is subtracted from L1, which is the initial value (that is, L1−ΔL = L1−α · ΔT). Can be estimated.

Thus, after the optical flow 501 has disappeared from the image plane 1100, the other vehicle 110
The movement of 1 can be inferred with high validity,
Further, the risk determination unit 107 determines whether the movement of the other vehicle 1101 estimated in this manner corresponds to a state corresponding to a predetermined high-risk situation.

That is, when the optical flow 501 immediately before disappearance has a direction component that is directed upward from the horizontal, the risk determination means 107 can be said to be based on, for example, the example of FIG. As in the case of the other vehicle 1301, the other vehicle 1301 that is traveling at a low speed on a road with a relatively sharp curve,
3 away from the image plane 110
If you go out of the 0 frame,
It can be considered that this corresponds to a case where the vehicle has gone out of the frame due to a branch of the road as in the case of the other vehicle 1302. In such a case, it is meaningless to execute the above estimation. Therefore, except in such cases,
Only when the optical flow 501 immediately before disappearance has a directional component directed downward from the horizontal, the above-described estimation is performed by the blind spot inter-vehicle distance estimation means 105, and the result of the estimation is used to calculate the distance. Risk determination means 1
When 07 determines that the danger is high, the danger is warned to the driver by an alarm buzzer 110 which is also used together with the alarm generation means 109.

The risk determining means 107 simply determines whether the other vehicle 11 has entered the blind spot area 1200 as described above.
In addition to the determination of the risk of 01, it is also possible to perform the determination of the risk at the time of the conventional general rearward monitoring such as the determination of the risk of the following vehicle (not shown) with respect to the own vehicle 1103. Needless to say, there is.

That is, the optical flows 500 and 501
The other vehicle 1 traveling in the adjacent lane 1204 depends on whether the vehicle is traveling in a direction diverging from the FOE 1208 or in a direction converging on the FOE 1208.
101 and own vehicle 110 at the speed of the following vehicle (not shown)
The degree of approach to (3) (that is, the degree of danger) is determined. That is, it is determined that the risk is higher as the optical flows 500, 501, and the like are farther from the FOE in the diverging direction. And if so, it issues an alert. Alternatively, it goes without saying that the warning light may be turned on.

By the way, as shown in FIG. 7, for example, the alarm generating means 109 is provided in the blind spot area 1200 of the vehicle 1103.
When the own vehicle 1103 executes a movement such as a lane change while another vehicle 1101 is invading the vehicle, the own vehicle 11
In some cases, a serious accident may occur due to a collision between the vehicle 03 and another vehicle 1101.

Therefore, when another vehicle 1101 is in the blind spot area 1200 of the own vehicle 1103, the own vehicle 1103 turns on the direction indicator 108 to execute a movement such as a lane change. Is input, an alarm indicating the danger is issued to the alarm generating means 1.
09 makes the alarm buzzer 110 sound as audible information, and warns the driver to that effect. In the present embodiment, the criterion for determining whether or not to issue such an alarm is a state between the time when the other vehicle 1101 enters the blind spot area 1200 and the time when the other vehicle 1101 completely exits in front of the host vehicle 1103. In such a case, it is determined that the risk is high.

That is, the other vehicle 1101 overtakes the own vehicle 1103 at the relative speed α obtained as the initial value based on the optical flow 501 immediately before the other vehicle 1101 enters the blind spot area 1200 and disappears as described above. In a state until the vehicle completely exits in front of the own vehicle 1103, when the intention to change lanes is input (that is, input) by the direction indicator 108, it is determined that there is a high risk. A warning to that effect is issued. However, the present invention is not limited to this, and it goes without saying that various other criteria can be used.

Next, the operation of the vehicular rear side monitoring apparatus according to the present invention will be described focusing on the operation of estimating the movement of another vehicle entering a blind spot. FIG. 6 is a schematic flowchart for explaining the operation of the vehicle rear side monitoring device according to the present invention, particularly focusing on the operation of estimating the motion of another vehicle entering a blind spot.

First, the image pickup means 101 picks up an image of the rear view (s1). Subsequently, the feature point extracting means 102 identifies an image of another vehicle traveling in the rear or adjacent lane from the image of the rear side view, and identifies one point of the image of the other vehicle as a feature point A.
(S2).

Then, the corresponding point detecting means 103 detects a corresponding point A 'corresponding to the characteristic point A from an image taken as a frame at a time point next to the time point (s3).

Subsequently, the optical flow forming means 104
Forms a vector connecting the feature point A and the corresponding point A 'as the optical flow 500 of the feature point of the other vehicle (s4).

The detection of the corresponding point A 'and the formation of the optical flow 500 are performed until the corresponding point A' detected one after another for each successive frame reaches a predetermined area close to the outer frame of the image plane 1100. That is, the feature point A is repeated until the feature point A disappears from the outer frame of the image plane 1100 as a frame-out, and the optical flow 500 is formed each time (N of s5 to Y of s5).

The feature point A is the image plane 110
When the corresponding point A ′ shown in FIG. 5 reaches a predetermined area close to the outer frame of the image plane 1100 just before disappearing as a frame out from the outer frame of 0, the blind spot inter-vehicle distance estimating means 105 Is the image plane 1100 of the corresponding point A ′ of the other vehicle 101 at that time.
Based on the coordinates A ′ (x, y) above, the relative speed α and the coordinate P of the relative position of the other vehicle 1101 at that time
'(X, Y, Z) is obtained (s6).

Further, immediately before the feature point A (the rear end portion of the other vehicle) disappears as a frame-out from the outer frame of the image plane 1100, or the corresponding point A 'is located in a predetermined area near the outer frame of the image plane 1100. Using the distance L1 at the time of arrival as an initial value, the inter-vehicle distance L between the other vehicle 1101 and the host vehicle 1103 is calculated by the formula L1 -α.ΔT at each period ΔT (Y in s7). (S8a), the vehicle length of the host vehicle 1103 is added to the vehicle distance L to calculate a distance L2 from the front end of the host vehicle to the rear end of the other vehicle as shown in FIG. 7 (s8). L2 takes a positive value when the rear end of the other vehicle is behind the front end of the own vehicle, and takes a negative value when the rear end is ahead of the front end of the own vehicle.
Then, for the calculated distance L2, L2≥S, L2 <
S is determined (s9). Here, S is a safety margin set in advance so that an appropriate inter-vehicle distance can be maintained between the host vehicle and another vehicle that is present at the preceding position even if the host vehicle changes lanes. When the front is negative, for example, it is a negative value such as -10 m.

As a result of the above determination, if L2 ≧ S (Y in s9), and if the turn-on signal is input to the direction indicator 108 (Y in s10), an alarm is generated by the alarm generating means 109 (S10). s11). Subsequently, if the ON input of the direction indicator 108, that is, the lighting of the direction indicator is stopped, the process returns to s7 again, and the subsequent operations are repeated.

When L2 <S (N in s9), since the danger has decreased, the calculation of L, the relative speed α and the coordinates P '(X, Y,
The data of the value of Z) is reset, the process returns to s (step) 1, and the above operation is repeated from the beginning again (s
1). That is, when L2 <S, it is determined that the other vehicle 1101 that has once disappeared has exited the safety zone ahead of the distance S, and an alarm is generated by the alarm generating means 109 even if the direction indicator 108 is turned on. No longer occurs. In this way, the vehicle rear side monitoring device according to the present invention operates to estimate the movement of the other vehicle 1101 in the blind spot area 1200 and avoid the danger.

In this embodiment, the last point of the other vehicle 1101 is extracted as the feature point A. However, the extraction of the feature point A is not limited to this. One point at the head of the other vehicle 1101 may be extracted.

In this case, however, the length b of the other vehicle 1101 is compared with the method of obtaining the characteristic point A in the above embodiment.
The value of the inter-vehicle distance L deviates from the above case by the amount of the above, but one point at the forefront of the other vehicle 1101 is extracted as the feature point A while correcting such a deviation. You may do it.

In the above embodiment, the monitoring camera, that is, the image pickup means 101 has been described as being installed at a position substantially at the center of the rear end of the vehicle 1103. The technology of the present invention can be applied to each of the two units, one in each of two places on both the left and right sides behind 1103.

Further, in a situation where the optical flow disappears from the left and right edges of the screen to the outside of the screen, a predetermined time (for example, three seconds) on the expressway from the time when the optical flow disappears from the edge of the screen. The time required for passing, etc.) can be regarded as that the nearby vehicle is traveling in the blind spot area beside the own vehicle. Therefore, if an intention to change lanes is indicated by a turn signal or the like within the predetermined time, there is a high risk of occurrence of a lateral collision, and an alarm to that effect may be issued.

[0114]

As described above, according to the present invention,
First, the driver can reliably recognize the presence of another vehicle that is hard to visually recognize by entering the area around the own vehicle, particularly in the blind spot.

Second, when the optical flow moves within the image plane and reaches a predetermined area (the position of the image pickup cell) on the periphery of the image plane,
At the time of the next frame, the optical flow is the first
As described above, the image plane may be regarded as disappearing by going out of the frame of the image plane to the outside. As a result, it becomes possible to reliably recognize the presence of another vehicle that is hardly visually recognized by entering the blind spot area described in the first technology.

Thirdly, based on the inter-vehicle distance or relative positional relationship between the other vehicle and the own vehicle estimated by the blind spot inter-vehicle distance estimating means, the own vehicle at every moment is determined. The risk determining means can determine the degree of risk of contact or collision with all the other vehicles. Further, by displaying the warning to the driver and sounding an alarm buzzer, the danger of contact or collision between the vehicles can be avoided beforehand.

Fourth, when another vehicle has entered the blind spot area of the own vehicle, it is guessed that the other vehicle has entered the blind spot area. It is possible to solve the problem that a large accident is generated by issuing a warning to the effect of a large accident and causing a collision between the own vehicle and another vehicle.

Fifth, only when the vehicle really enters the blind spot area like another vehicle, it can be accurately determined and erroneous determination can be prevented.

Sixth, when a lane change operation is performed in a situation where another vehicle is in the blind spot area, a danger can be easily warned.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of a vehicle rear side monitoring device according to the present invention.

FIG. 2 is a diagram illustrating an example of a case where a host vehicle equipped with a vehicular rear side monitoring device according to the present invention is traveling on a road together with other vehicles.

FIG. 3 is a diagram illustrating an example of an image formed via a lens system on an image plane of an imaging unit in a state as illustrated in FIG. 2;

FIG. 4 is a diagram showing an example of an edge image detected from an image as shown in FIG. 3;

FIG. 5 is a diagram schematically showing a feature point A and an optical flow on an image plane.

FIG. 6 shows the operation of the vehicle rear side monitoring device according to the present invention;
6 is a schematic flowchart mainly illustrating an operation of estimating a motion of another vehicle having entered a blind spot.

FIG. 7 is a diagram showing an example of a case where a host vehicle equipped with a conventional vehicle rear side monitoring device is traveling on a road together with another vehicle.

FIG. 8 is a diagram showing an example of a case where a road having a relatively small radius of curvature and other vehicles running on the road are imaged as an image on an image plane of an imaging unit via a lens system;

FIG. 9 shows a temporally continuous image obtained by a camera which is an image pickup means attached rearward to the rear of the host vehicle, that is, within a frame of an image plane of an image pickup device such as a CCD image pickup device of the camera. FIG. 6 is a diagram showing an outline of an example of a rear side view obtained in FIG.

[Explanation of symbols]

 Reference Signs List 101 imaging means 102 feature point extracting means 103 corresponding point detecting means 104 optical flow forming means 105 blind spot inter-vehicle distance estimating means 106 display means 107 danger degree determining means 108 direction indicator 109 warning generating means 109'second warning generating means 110 Alarm buzzer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazutomo Fujinami 2771 Ooka, Numazu-shi, Shizuoka Prefecture F-term (reference) 5C054 FC01 FC12 FC13 FC14 FC15 FE28 FF06 GB01 HA30

Claims (6)

[Claims] 1. An image capturing means captures a rear side view from a running own vehicle by an imaging means, detects a temporal movement of a corresponding point in two frames preceding and succeeding a predetermined time as an optical flow, and detects a backward movement with respect to the own vehicle. Alternatively, in a vehicle rear side monitoring device that monitors an approaching state of another vehicle traveling in an adjacent lane, the other vehicle traveling in the rear or adjacent lane from an image of the rear view taken at a certain time Feature point extracting means for extracting at least one point of the image as a feature point, and a corresponding point detecting means for detecting a corresponding point corresponding to the feature point from an image captured as a frame at a time point next to the time point, An optical flow forming means for forming a vector connecting the feature point and the corresponding point as an optical flow of the feature point of the other vehicle; and When the frame disappears from the frame of the image plane that can be imaged by the imaging means outwardly, based on the optical flow of the feature point of the other vehicle immediately before the disappearance, the optical point of the feature point of the other vehicle is used. A vehicle comprising: a blind spot inter-vehicle distance estimating means for estimating at least one of an inter-vehicle distance and a relative positional relationship between the other vehicle and the host vehicle after the flow disappears. For rear side monitoring device. 2. The rear-side monitoring device for a vehicle according to claim 1, wherein the blind spot inter-vehicle distance estimating unit is configured such that an optical flow of a feature point of the other vehicle is within a frame of an image plane that can be imaged by the imaging unit. When the optical flow reaches a predetermined area of the peripheral portion of the other vehicle, it is considered that the optical flow disappears at the time of the next frame, and the optical flow at the time of the arrival reaches the other vehicle immediately before the disappearance. Estimating at least one of an inter-vehicle distance and a relative positional relationship between the other vehicle and the own vehicle after the arrival or at the time of the next frame after the arrival using the optical flow of the feature point. A rear side monitoring device for a vehicle, which is a blind spot inter-vehicle distance estimation means. 3. The rear-side monitoring device for a vehicle according to claim 1, wherein the inter-vehicle distance or the relative positional relationship between the other vehicle and the own vehicle estimated by the blind spot inter-vehicle distance estimation unit. A rear-side monitoring device for a vehicle, further comprising: a risk determination unit configured to determine a degree of risk of contact or collision with the other vehicle based on the vehicle. 4. The rear side monitoring device for a vehicle according to claim 1, wherein the inter-vehicle distance or the relative distance between the other vehicle and the own vehicle estimated by the blind spot inter-vehicle distance estimation unit. When the relative positional relationship is within a predetermined range as a state where there is a risk of contact or collision with the other vehicle with respect to the own vehicle, the own vehicle is provided with an indication of intention when changing lanes. When an input to turn on the installed direction indicator is made, an alarm generation unit that issues an alarm indicating the danger at least one of audio information and visual information is further provided. A rear side monitoring device for a vehicle, comprising: 5. The rear-side monitoring device for a vehicle according to claim 1, wherein the blind spot inter-vehicle distance estimating unit is configured to determine a peripheral portion in a frame of an image plane that can be imaged by the imaging unit. If the optical flow of the characteristic point of the other vehicle at the time of reaching the area is an optical flow having a directional component corresponding to a direction from the horizontal direction to the upward direction in the rear view, Alternatively, without estimating the inter-vehicle distance and the relative positional relationship between the other vehicle and the own vehicle after the time of the frame next to the time, the peripheral edge within the frame of the image plane that can be imaged by the imaging means. The optical flow of the feature point of the other vehicle at the time when the vehicle reaches the predetermined area of the portion has a direction component corresponding to a direction from the horizontal direction to the lower side in the rear view. Only when there is an optical flow of a characteristic point of another vehicle entering the blind spot of the own vehicle, the other vehicle and the own vehicle between the time when the vehicle arrives or the time of the next frame after the time are reached. A rear-side monitoring device for a vehicle, which is a blind spot inter-vehicle distance estimating means for estimating at least one of an inter-vehicle distance and a relative positional relationship between the two. 6. The rear side monitoring device for a vehicle according to claim 1, wherein an optical flow of a feature point of the other vehicle is directed outward from a frame of an image plane that can be imaged by the imaging unit. In the case where the vehicle disappears due to frame out, when an operation for changing lanes is performed within a certain period of time after the disappearance, a warning that there is a risk of occurrence of a lateral collision is given by an audible information and a visual warning. A rear side monitoring device for a vehicle, further comprising a second alarm generating means for issuing at least one of target information.