JP3406195B2 - Vehicle distance measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention compares a pair of image signals formed on an image sensor by a pair of optical systems, electrically detects the deviation amount of both images from the optical axis, and performs triangulation. The present invention relates to a vehicle distance measuring device that measures a distance to an object by executing a calculation based on the principle using the shift amount.

[0002]

2. Description of the Related Art Conventionally, a vehicle distance measuring device for measuring a distance to an object such as a preceding vehicle while tracking the object has been known.
For example, it is known from Japanese Patent Laid-Open No. 6-241787, and in this, whether or not an object is reliably tracked is determined in order to obtain a distance measurement value to the object and image information of the object. An error signal is output when the position of the tracking window is used to determine that tracking of the target object is no longer possible.

[0003]

By determining whether or not the object is being reliably tracked, it is possible to avoid erroneous distance measurement due to uncertain tracking of the object. When the measured distance to the object is used for vehicle traveling control, it is possible to recognize in which direction the object can no longer be tracked, and it is possible to control the vehicle more precisely. Will be. That is, if the target object cannot be tracked on either the left or right, it can be expected that the road is curved, and if the target object cannot be tracked on either the up or down direction, it can be tracked. It can be expected that the road is a slope or an uneven road. Therefore, it is desirable to be able to determine in which direction the object cannot be tracked, in addition to determining whether or not the object to be tracked is being reliably tracked. It only determines whether or not the tracking window of the target object exists in the movable area estimated from the measured value, and it is not known in which direction the target object cannot be tracked.

The present invention has been made in view of the above circumstances, and makes it possible to determine whether or not an object is being reliably tracked in order to obtain an accurate distance measurement value. It is an object of the present invention to provide a vehicle distance measuring device capable of determining in which direction the vehicle cannot be tracked when the vehicle cannot track the vehicle.

[0005]

In order to achieve the above object, the invention according to claim 1 compares a pair of image signals formed on an image sensor by a pair of optical systems and compares the optical axes of both images. In a vehicle distance measuring device that electrically detects a deviation amount from the object and executes a calculation based on the principle of triangulation using the deviation amount to measure the distance to the object, When it is determined that tracking is not possible and whether the object is out of the field of view set in the screen obtained by both image sensors, and when tracking is not possible Tracking propriety / impossible direction judging means for judging the direction in which the object cannot be tracked, and the both image sensors
In the selection area of the image information from within the screen obtained by
And Ui-end determining means for determining a certain window, the window
Correlation performance of image data in the window determined by the determination means
Correlation to obtain the amount of deviation from the optical axis of both images
And a tracking enable / disable direction determining means,
The pair obtained based on the correlation calculation by the correlation calculation means.
It is added that the image center of the elephant is outside the field of view.
It is determined that the tail cannot be reached and the image center is the visual field region.
Tracked by judging whether it is outside of the top, bottom, left, or right of
It is characterized in that the direction in which it becomes impossible is determined .

The invention according to claim 2 is the above-mentioned claim 1.
In addition to the configuration of the described invention , the correlation in the correlation calculating means
Distance calculator that calculates the distance to the object based on the calculation
Equipped with a step, and up and down by the tracking possibility / impossible direction determining means.
If it is determined that tracking in the direction is impossible, the tracking
Only when it is impossible, the distance output from the distance calculation means is
It is characterized in that it is replaced by the distance immediately before tracking becomes impossible .

The invention according to claim 3 is a pair of optical systems.
To compare a pair of image signals formed on the image sensor.
In comparison, the amount of deviation from the optical axis of both images is detected electrically and
Perform the calculation based on the principle of angular surveying using the deviation amount.
For distance measurement devices for vehicles that measure the distance to the target object
And whether or not the object can be tracked by the both image sensors.
From the field of view set in each of the obtained screens
Determined by whether or not it is out and determined that tracking is not possible
When you do, the object is in the field of view
Those who cannot track the object depending on whether it is out of the area
It is equipped with a tracking possibility / impossible direction determining means for determining the direction.
Tracking in the up / down direction is not possible due to the tracking enable / disable direction determining means.
If it is determined to be possible, only during the period when tracking is not possible,
Replace with the distance immediately before the distance to the target becomes untrackable
It is characterized by being obtained.

According to the features of claims 1 to 3, when the object is out of the field of view, the object is not surely tracked. Therefore, uncertain tracking is performed by determining that tracking is impossible. It is possible to prevent an erroneous measurement due to the measurement from occurring and to perform accurate distance measurement. Also, when determining whether or not the object has deviated from the field of view, the object can be viewed from the field of view in any of up, down, left, and right directions. Since it can be easily determined whether or not the object is out of the range, it is possible to easily determine the direction in which the object cannot be tracked, and the direction in which the object cannot be tracked can be effectively used for vehicle traveling control or the like.

Further, in particular, according to the above features of claims 1 and 2,
For example, target based on the correlation calculation of image data in the window
By determining the image center of the object, the object is outside the field of view.
Whether or not it has been hit, and whether the field of view is up, down, left, or right
It is possible to easily determine whether or not the object has come off.
It

Further, in particular according to the above feature of claim 3,
Tracking in the vertical direction is impossible by the tail possibility / impossible direction determination means
If it is determined that the untracked time is
Since it is relatively short,
Replaces the distance to the object with the distance immediately before tracking becomes impossible
Can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described based on an embodiment of the present invention shown in the accompanying drawings.

1 to 5 show a first embodiment of the present invention, FIG. 1 is a block diagram showing the structure of a distance measuring device, FIG. 2 is a diagram for explaining the principle of distance measuring, and FIG. FIG. 4 is a diagram showing a change of a window with a distance change, FIG. 4 is a diagram showing a visual field area and a layout of windows on a screen determined by an image sensor, and FIG. 5 is a diagram for explaining a determination as to whether tracking is possible or not. Is.

First, in FIG. 1, a pair of upper and lower image pickup means 1
A and 1B are arranged inside the vehicle interior of the vehicle, for example, on the rear side of the windshield, and these image pickup means 1A and 1B are arranged.
The image signal of the object 4 such as the preceding vehicle obtained in
The signals are converted into digital signals by the / D converters 5A and 5B and further stored in the individual image storage means 6A and 6B.

Of the image signals stored in the image storage means 6A and 6B, only the image signal of the window determined by the tracking window determination means 7 is cut out, the correlation calculation means 8 executes the correlation calculation, and the correlation is calculated. The distance D to the object 4 is calculated by the distance calculation means 9 based on the calculation result.

In FIG. 2, both image pickup means 1A and 1B are
Optical systems 2A and 2B including lenses, and those optical systems 2
Each of the optical systems 2A and 2B is arranged with a base line length BL and is vertically spaced from each other by the image sensors 3A and 3B, which are arranged behind the focal lengths f of A and 2B, respectively.

According to such image pickup means 1A and 1B,
The object 4 such as a preceding vehicle existing in front of the own vehicle is the optical system 2
An image is formed on the image sensors 3A and 3B by A and 2B. The image sensors 3A and 3B are, for example, a two-dimensional CCD in which a large number of pixels are dispersed in a two-dimensional plane.
Or PD.

In the screen determined by the image sensors 3A and 3B, as shown in FIG. 3, a single window W ₁ shown by hatching is set by the window determining means 7, and the image signal in this window W ₁ is set. Is input to the correlation calculation means 8 from the image storage means 6A, 6B, and both image sensors 3A, 3
The correlation calculating means 8 executes the calculation for obtaining the shift amount n at the point where the correlation of the brightness data obtained from B is the best match. That is, one of the images of both image sensors 3A and 3B is shifted, or both of the images of both image sensors 3A and 3B are alternately shifted, the subtraction of both image signals is executed, and both image data are the best match. When I did
That is, the correlation calculating means 8 performs the calculation for obtaining the shift amount n when the correlation value becomes the minimum. Thus, the shift amount n is, as shown in FIG.
It is obtained as the sum of the deviation amount nA of the image signal obtained from A from the optical axis of the optical system 2A and the deviation amount nB of the image signal obtained from the upper image sensor 3B from the optical axis of the optical system 2B. It will be. Further, in calculating the shift amount n, the resolution is determined by the interval between the pixels in the image sensors 3A and 3B. Therefore, in order to improve the resolution, interpolation between the intervals is performed to correct the shift amount n. May be.

The distance calculation means 9 executes the distance calculation based on the principle of the triangulation method, and the distance D to the object 4 is D = (BL × f) / n by the distance calculation means 9. Will be obtained. On this occasion,
A temperature sensitive element may be arranged near the image sensors 3A and 3B, and the distance D may be corrected based on the temperature information obtained by the temperature sensitive element.

The distance D obtained by the distance calculation means 9 is input to a vehicle travel control device 10 for causing the subject vehicle 4 such as a preceding vehicle to travel, for causing the vehicle to travel.

The distance D obtained by the distance calculating means 9 is input to the window determining means 7, and the window determining means 7
The size of the window W ₁ is corrected based on the distance D. As a result, as shown in FIG. 3, the size of the window W ₁ changes according to the distance to the object 4 such as the preceding vehicle.

On the other hand, the correlation calculation result of the correlation calculation means 8 is input to the preceding vehicle direction estimation means 11. In the preceding vehicle direction estimating means 11, the moving direction of the object 4 such as the preceding vehicle is determined by tracking the image center of the object 4 obtained based on the correlation calculation in the correlation calculating means 8 in time series. . Thus, the moving direction of the object 4 estimated by the preceding vehicle direction estimating means 11 is input to the vehicle travel control device 10 and the window determining means 8, and the window determining means 7 moves the object 4. The position of the next window W ₁ will be determined according to the direction.

The moving direction estimated by the preceding vehicle direction estimating means 11 is input to the tracking enable / disable direction determining means 12. This tracking propriety / impossible direction determination means 12 is used for the object 4
It is for determining whether or not tracking is being performed reliably, that is, whether or not tracking is possible, and when determining that tracking is not possible, in which direction, up, down, left, or right, tracking is not possible, that is, whether or not it is impossible. As shown in FIG. 4, both image sensors 3A and 3A are used as a reference for making a determination.
The visual field area _AV is set within the screen determined by B. In Thus to trackability-Call direction determination unit 12, based on the estimated result in said preceding vehicle direction estimation means 11, the tracking of the object 4 when the image center of the object 4 is out of the viewing area A _V with determination and becomes uncertain, which determines the direction in which a tracking not the object 4 by one image center of the object 4 is out of the field area a _V in any vertical and horizontal direction, FIG. 5 (A) is in the right direction, and in the state shown in FIG. 5 (B) is in the left direction, FIG.
In the state shown in (C), it is determined that the tracking cannot be performed in the downward direction, and in the state shown in FIG.

The determination result by the tracking enable / disable direction determining means 12 is input to the vehicle running control device 10.

Next, to explain the action of this first embodiment, when the image center of the object 4 from the field area A _V comes off is not a state in which reliably track the object 4, and tracking disabled By making the determination, it is possible to prevent erroneous measurement due to uncertain tracking and perform accurate distance measurement. The control accuracy of the vehicle travel control device 10 can be improved based on the accurate distance measurement.

[0025] It is easy to determine the center of the image field area A object from _V 4 is deviated whether the determination time to the object from the viewing area A _V in the vertical left or right direction 4 is detached, the subject The direction in which the object 4 cannot be tracked can be easily determined. Therefore, if the target object 4 cannot be tracked on either the left or right, it can be predicted that the road is curved in front of the vehicle, and the target object 4 cannot be tracked on either the up or down direction. If so,
It can be predicted that the traveling road is a slope or an uneven road in front of the own vehicle, and the control by the vehicle traveling control device 10 can be performed more finely.

As a second embodiment of the present invention, as shown in FIG. 6, the distance D obtained by the distance calculating means 9, the preceding vehicle direction estimated by the preceding vehicle direction estimating means 11, and the tracking enable / disable direction The determination result of the determination means 12 may be displayed on the display means 13, which allows the driver to perform the steering operation by himself based on the information displayed on the display means 13.

FIG. 7 shows a third embodiment of the present invention, in which the distance D obtained by the distance calculating means 9 is calculated based on the judgment result of the tracking propriety / impossible direction judging means 12 and the inter-vehicle distance processing means 14 Is processed in. The inter-vehicle distance processing means 14 processes the distance D based on the determination result of the tracking enable / disable direction determining means 12. For example, when it is determined that vertical tracking is not possible, the tracking is impossible. Since the time is relatively short, the inter-vehicle distance processing means 14 performs processing such that the distance D output from the distance calculation means 9 is replaced with the distance D immediately before the tracking is disabled only while the tracking is disabled. Be done.

8 to 11 show a fourth embodiment of the present invention, FIG. 8 is a block diagram showing the configuration of a distance measuring device, and FIG. 9 is a diagram showing changes in the distance of a window. 10, FIG. 10 is a diagram showing the arrangement of the field of view and the window on the screen determined by the image sensor, and FIG. 11 is a diagram for explaining the determination as to whether tracking is possible or not.

First, in FIG. 8, a pair of upper and lower image pickup means 1
The image signals of the object 4 such as the preceding vehicle obtained in A and 1B are transferred to the image storage means 6 via the A / D converters 5A and 5B.
They are stored in A and 6B, respectively.

In the window determining means 7, as shown in FIG. 9, a plurality of small windows W ₂ , W _2, ... Are estimated by the distance D obtained by the inter-vehicle distance calculating means 17 and the preceding vehicle direction estimating means 12. It is determined based on the direction of the preceding vehicle. Thus, the positions and sizes of the windows W ₂ , W ₂ ... Have fixed values, and the adopted windows W ₂ , W ₂
The position and the number of ... Are determined by the window determining means 7.

Image information corresponding to each window W ₂ , W ₂ ... Is cut out from the image storage means 6A, 6B, and correlation calculation means 8 ₁ ... 8 _n individually corresponding to each window W ₂ , W ₂ ...
To the respective correlation calculation means 8 ₁ to 8 _n.
In this case, the correlation calculation of the image signals for each combination of the windows W ₂ corresponding to each other is executed, and the shift amount n for each window W ₂ is obtained by each correlation calculation means 8 ₁ to 8 _n. become.

Distance calculation based on the shift amount n obtained by each of the correlation calculation means 8 ₁ to 8 _n is performed by the distance calculation means 9 ₁ to
9 _n are executed respectively. These distance calculation means 9 ₁
The distances obtained at ˜9 _n are the window output evaluation means 15 ₁
15 is intended to be evaluated respectively by _n, the distance to the object 4 by the inter-vehicle distance calculating means 17 based on the distance to be evaluated by the window output evaluation means 15 ₁ to 15 _n when captures an object 4 D Is calculated.

On the other hand, the tracking enable / disable direction determining means 12
, Together with the tracking of the object 4 is determined to have become unreliable when set image center of the object 4 from the field area A _V goes out as shown in Figure 10, the image center of the object 4 The direction in which the object 4 cannot be tracked is determined depending on which of the up, down, left, and right directions deviates from the visual field area A _{V. In the} state shown in FIG. 11) in the state shown in FIG.
In the state shown in (C), it is determined that tracking cannot be performed in the downward direction, and in the state shown in FIG.

The fourth embodiment can also achieve the same effects as the first embodiment.

In the above embodiment, the image sensors 3A, 3A
B is a two-dimensional image sensor in which a large number of pixels are dispersed and arranged on a plane, but a vehicle distance in which a one-dimensional image sensor including a plurality of line image sensors arranged in parallel to each other is used The present invention can also be applied to a measuring device.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the present invention described in the claims. It is possible to do.

[0037]

As described above, according to each of the first to third aspects of the present invention, by determining that tracking is impossible, it is possible to prevent erroneous measurement due to uncertain tracking and to perform accurate distance measurement. It becomes possible to carry out the control, and the direction in which the object cannot be tracked is determined, so that it can be effectively used for vehicle traveling control and the like.

[0038] According to a particularly claim 1, 2 of the invention, c
Based on the correlation calculation of image data in India
Does the object deviate from the visual field by finding the image center?
And whether it is outside the field of view in any direction
You can easily determine if the elephant has come off.

According to the inventions of claims 2 and 3, in particular,
Tracking in the vertical direction is impossible by the tail possibility / impossible direction determination means
If it is determined that the untracked time is
Since it is relatively short,
Replaces the distance to the object with the distance immediately before tracking becomes impossible
Can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a distance measuring device according to a first embodiment.

FIG. 2 is a diagram for explaining the principle of distance measurement.

FIG. 3 is a diagram showing a change with a change in distance of a window.

FIG. 4 is a diagram showing the arrangement of a field of view and a window on a screen determined by an image sensor.

FIG. 5 is a diagram for explaining whether or not tracking is possible and whether or not tracking is possible.

FIG. 6 is a block diagram showing a configuration of a distance measuring device according to a second embodiment.

FIG. 7 is a block diagram showing a configuration of a distance measuring device according to a third embodiment.

FIG. 8 is a block diagram showing the configuration of a distance measuring device according to a fourth embodiment.

FIG. 9 is a diagram showing a change with a change in window distance.

FIG. 10 is a diagram showing the arrangement of a visual field area and a window on a screen determined by an image sensor.

FIG. 11 is a diagram for explaining whether or not tracking is possible and whether or not tracking is possible.

[Explanation of symbols]

2A, 2B ... optical system 3A, 3B ... image sensor 4 ... object 7 ... window determining means 8; 8 ₁ ~8 _n ··· correlation computing unit 12 ... trackability-Call Direction determination means A _V ... Field of view

Continuation of the front page (56) Reference JP-A-6-241787 (JP, A) JP-A-5-108149 (JP, A) JP-A-6-109467 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01C 3/06 G01B 11/00 G06T 1/00 315 G06T 7/60 180

Claims (3)

(57) [Claims] 1. A pair of image signals formed on an image sensor (3A, 3B) by a pair of optical systems (2A, 2B) are compared to electrically detect a deviation amount of both images from an optical axis. In a vehicle distance measuring apparatus that measures a distance (D) to an object (4) by executing a calculation based on the principle of triangulation using the deviation amount, whether or not the object (4) can be tracked Image sensor (3
(A, 3B) is determined by whether or not the object (4) deviates from the visual field area (A _V ) set in the screen obtained respectively, and when it is determined that tracking is impossible, the object (4 Tracking permission / non-direction determination means (12) for determining the direction in which tracking of the object (4) is disabled depending on whether 4) is out of the visual field area (A _V ) , and both image sensors (3A, 3B). Each obtained with
The window that is the selection area of the image information from the screen
Window determining means (7) and the window determined by the window determining means (7)
Correlation operation of the image data in (W ₁ , W ₂ )
Correlation calculation means (8; 8) for obtaining the amount of deviation of the image from the optical axis
₁ to 8 _n) and wherein the trackability-Call direction determination means (12), the correlation
Based on the correlation calculation in the calculation means (8; 8 ₁ to 8 _n ),
The center of the image of the object (4) to be attached is the visual field region.
(A _V ) If it is determined that tracking is not possible when it is outside
The center of the image is above , below, left, and right of the visual field area (A _V ).
Tracking became impossible due to the judgment of whether it exists outside the gap
A vehicle distance measuring device characterized by determining the direction . 2. The correlation calculation means (8; 8 ₁ to 8 _n )
The distance (D) to the object (4) is calculated based on the correlation calculation of
Equipped with a distance calculation means (9) for calculating, and up and down by the tracking availability / impossible direction determination means (12).
If it is determined that tracking of the direction is impossible, the tracking
The distance output from the distance calculation means (9) only during the period
Replace with the distance (D) immediately before the distance (D) becomes untrackable
Characterized in that it is, the vehicle distance measuring apparatus according to claim 1. 3. A pair of image signals formed on an image sensor (3A, 3B) by a pair of optical systems (2A, 2B) are compared to electrically detect a deviation amount of both images from an optical axis. In a vehicle distance measuring apparatus that measures a distance (D) to an object (4) by executing a calculation based on the principle of triangulation using the deviation amount, whether or not the object (4) can be tracked Image sensor (3
(A, 3B) is determined by whether or not the object (4) deviates from the visual field area (A _V ) set in the screen obtained respectively, and when it is determined that tracking is impossible, the object (4 4) is provided with a tracking enable / disable direction determining means (12) for determining a direction in which tracking of the object (4) is disabled depending on whether or not the tracking area (A _V ) is out of the view area (A _V ). Up and down by (12)
If it is determined that tracking of the direction is impossible, the tracking
The distance (D) to the object (4) cannot be tracked only during the time
A distance measuring device for a vehicle, which is replaced by a distance (D) immediately before .