JP3382518B2 - 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 relates to a vehicle distance measuring device, and more particularly to a pair of optical systems, a pair of image sensors for forming images from the optical systems, and a combination of the image sensors. A window determining means for determining a window of a pair of imaged images, a correlation calculating means for comparing an image signal in the window determined by the window determining means to detect a deviation amount from the optical axis of both images, and the correlation calculating means. The present invention relates to a distance measuring device for a vehicle, which is provided with a distance calculating means for calculating a distance to an object by executing a calculation based on the principle of triangulation using the shift amount obtained in step 1.

[0002]

2. Description of the Related Art Conventionally, such a distance measuring device is already known, for example, in Japanese Patent Laid-Open No. 4-218715.
In this configuration, as shown in FIG. 5, a first window W1 that surrounds an object such as a preceding vehicle and a second window W2 that is located above and adjacent to the first window W1 are set. Distance calculating means for calculating the distance to the object based on the image information of the two windows W1 and W2 respectively, and the position of the first window W1 is corrected based on the distance information obtained by both distance calculating means. And a means for obtaining the distance to the object based on the image information of the first window W1 corrected when the own vehicle pitches.

[0003]

SUMMARY OF THE INVENTION In the above conventional one,
A second window W2 for obtaining an image including the background of the object is set above the first window W1, and the distance based on the image information of the second window W2 is the first window W1.
However, since an irregular target such as the sky is included in the second window W2, the distance calculation error becomes large and the inappropriate window position correction is performed. May occur. Also, as shown in FIG. 6, when downward pitching occurs, the first
There is a possibility that road surface characters will be included in the window W1 and the distance to an object such as a preceding vehicle will be shorter than it actually is.

The present invention has been made in view of the above circumstances, and is for a vehicle capable of appropriately correcting the window position when pitching occurs and enabling the distance to an object to be accurately obtained. An object is to provide a distance measuring device.

[0005]

In order to achieve the above object, the present invention comprises a pair of optical systems, a pair of image sensors for forming images from the optical systems, respectively.
Correlation calculating means for comparing the image signals in the windows determined by the window determining means with the window determining means for determining the windows of the pair of images formed on both image sensors, and detecting the amount of deviation from the optical axis of both images. And a distance calculation means for calculating a distance to an object by executing a calculation based on the principle of triangulation using the shift amount obtained by the correlation calculation means. Relative momentum computing means for determining at least one of relative velocity and relative acceleration / deceleration with the object based on the distance data obtained by the means, and at least the relative velocity and relative acceleration / deceleration obtained by the relative momentum computing means. Pitching determination means for determining that a pitching change of a predetermined amount or more has occurred when one of them changes so as to satisfy a predetermined condition, and pitching change of a predetermined amount or more. Resulting said pitching determining means and the first; and a window position correcting means for substantially correcting the window of the vertical position according to judgment.

According to the configuration of the first feature, when the pitching of the vehicle occurs, the change amount of the relative speed or the relative acceleration / deceleration with respect to the object should be large,
Relative velocity and relative acceleration
When at least one of the deceleration changes so as to satisfy a predetermined condition, it can be determined that a pitching change of a predetermined amount or more has occurred, and when the pitching determination means determines that the own vehicle has pitched, the target object The vertical position of the window that is set to obtain the distance to is substantially corrected, and the distance to the object can be accurately measured even if pitching occurs.

The present invention, in addition to the above first feature,
The pitching determination means is configured to determine that a pitching change of a predetermined amount or more has occurred when the sign of the relative velocity obtained by the relative momentum calculation means is inverted.
As a second characteristic, and in addition to the first characteristic,
The pitching determination means is configured to determine that a pitching change of a predetermined amount or more has occurred when the absolute value of the relative acceleration / deceleration obtained by the relative momentum calculation means exceeds a set value.
The third feature is to be performed .

The present invention also provides the above-mentioned first, second or third
In addition to the features, the window determination means is
A tracking window for determining the distance and the tracking window
Set the road surface detection window installed below and
The means for determining the matching is based on the road surface detection window.
The pair velocity is close to the relative velocity based on the tracking window
Based on the above, it is determined that upward pitching has occurred in the vehicle.
The fourth characteristic is to determine .

[0009]

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 3 show a first embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of a distance measuring device, and FIG. 2 is a diagram for explaining the principle of distance measuring. FIG. 6 is a diagram showing a window arrangement.

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 step 1 is converted into a digital signal by the individual A / 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 window determination means 7 is cut out, and the correlation operation means 8 executes the correlation operation. Based on the result, the distance calculating means 9 calculates the distance D to the object 4.

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,
An object 4 such as a preceding vehicle existing in front of the own vehicle is an 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.

As shown in FIG. 3, a single window W is set by the window determining means 7 in the entire image obtained by the image sensors 3A and 3B, and the image signal in the window W is stored in the image storing means. Correlation calculation means 8 from 6A and 6B
Are input to the image sensor 3A, 3B, and the correlation calculation means 8 performs a calculation for obtaining the shift amount n at the point where the correlations of the brightness data obtained from both the image sensors 3A and 3B are 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 that is the case, that is, when the correlation value becomes the minimum, the correlation calculation means 8 performs the calculation to obtain the shift amount n. Therefore, the shift amount n is as shown in FIG.
As shown in, the shift amount nA of the image signal obtained from the lower image sensor 3A from the optical axis of the optical system 2A and the optical system 2 of the image signal obtained from the upper image sensor 3B.
It is obtained as the sum of the deviation amount nB of B from the optical axis. 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 follow and drive the vehicle.

The pitching change of the vehicle is calculated by the distance calculating means 9
Pitching change detecting means 1 based on the distance D obtained in
The pitching change detection means 11 calculates the relative velocity and relative acceleration / deceleration with respect to the object 4 based on the distance data obtained by the distance calculation means 9. Means 12 and pitching determination means 13 for determining that a pitching change of a predetermined amount or more has occurred when the relative speed and the relative acceleration / deceleration obtained by the relative momentum calculation means 12 satisfy predetermined conditions.

In the relative momentum calculation means 12, the relative speed V and the relative acceleration / deceleration A are added to the previous value by the subscript (n-1) and the current value by the subscript (n). the period when the t, are respectively calculated by the following calculation formula _{V n = (D n -D n} -1) / t a n = (V n -V n-1) / t. If only the difference calculation is performed at the time of calculation by the relative momentum calculation means 12, the distance noise may be enlarged, so a filter calculation such as low pass may be performed.

The pitching judging means 13 determines that the relative velocity V _n and the relative acceleration / deceleration A _n obtained by the relative momentum calculating means 12 meet the following first and second conditions, respectively, and are equal to or more than a predetermined amount. It is determined that the pitching change has occurred.

First condition: V _n × V _n-1 <0 Second condition: | A _n |> Judgment value The first condition is to judge whether or not the sign of the relative speed V is inverted from the previous time. The second condition is to judge whether or not the absolute value of the relative acceleration / deceleration A exceeds the judgment value. When both the first and second conditions are satisfied, the road surface at the bottom of the window is The pitching determination means 13 determines that pitching that includes characters has occurred in the vehicle.

When the pitching determination means 13 determines that a pitching change of a predetermined amount or more has occurred, the position of the set window W by the window determination means 7 is corrected by the window position correction means 14, and this window position is corrected. The correction means 14 is composed of a window position correction calculation means 15 and a position correction storage means 16 for storing the correction value obtained by the window position correction calculation means 15.

In the window position correction calculation means 15, the correction value S is calculated by the following calculation formula using the coefficient G and the relative acceleration / deceleration A _n .

S = G × A _{n In the} arithmetic expression, the sign of the coefficient G is the relative acceleration / deceleration A
_The window is set to be corrected to the upper position when _n becomes large in the direction in which the object 4 approaches the own vehicle.

The correction value S calculated by the window position correction calculation means 15 is temporarily stored in the position correction storage means 16 and is determined by the window determination means 7 with the correction value S stored in the position correction value storage means 16. The next window position will be corrected.

The operation of the first embodiment will now be described. When pitching of the vehicle occurs, the amount of change in relative velocity V and relative acceleration / deceleration A with the object 4 should be large. Therefore, the pitching determination means 13 can determine that the pitching change of a predetermined amount or more has occurred when the relative speed V and the relative acceleration / deceleration A are changed so as to satisfy the first and second conditions, respectively.

When the pitching change detecting means 11 detects that pitching has occurred in the vehicle, the position of the window determined by the window determining means 7 is corrected upward or downward, which results from the occurrence of pitching. Therefore, it is possible to prevent the distance measurement error due to the inclusion of road surface characters in the window, and to accurately measure the distance to the object 4 even if pitching occurs.

The correction value S in the window determining means 7 is
It is determined by the window position correction calculation means 15 according to the degree of pitching, and it becomes possible to set the window at an appropriate position and perform more accurate distance measurement.

Further, since it is possible to correct the positional deviation due to pitching with one window, the calculation time is longer than that of the conventional one (Japanese Patent Laid-Open No. 4-218715) in which distance calculation is performed with a plurality of windows. Can be shortened.

Although the distance measuring device using a single window has been described in the first embodiment, the present invention is also applied to the distance measuring device using a plurality of windows as in the second embodiment shown in FIG. It is possible.

In FIG. 4, among a plurality of windows, for example, a window in which a good correlation is obtained due to a large difference between the minimum value of the correlation value and the correlation values before and after the minimum value, or obtained for each window. minimum or previous resulting object 4 to the tracking window W _P so that the window within the scope of up to a certain distance from the distance indicated by the stippling in distance is, W _P thereof with defined as ... tracking window W _P, W _P ...
The average value of the distances is determined as the distance to the object 4,
The correction value S is calculated based on the relative acceleration / deceleration A _n1 based on the distance obtained from the tracking windows W _P , W _P ... And the coefficient G _1.
1 is defined as S ₁ = G ₁ × A _n1 , and the sign of coefficient G ₁ is relative acceleration / deceleration A
_The window is set to be corrected to the upper position when _n1 becomes large in the direction of _{approaching the host} vehicle.

On the other hand, below each of the tracking windows W _P , W _P ... As shown by the diagonal lines, a plurality of road surface detection windows W _R , W
_R ... is set, and the correction value S ₂ is based on the relative acceleration / deceleration A _n2 based on the average value of the distances of these road surface detection windows W _R , W _R ... And the coefficient G _2. , S ₂ = G ₂ × A _n2 , and the sign of the coefficient G ₂ is opposite to that of the coefficient G ₁ when the relative acceleration / deceleration A _n2 increases in the approaching direction to the vehicle. It is set to correct the window to the lower position.

When the pitching of the vehicle is detected, the tracking window W is calculated by the average value of the correction values S ₁ and S _2.
The vertical positions of _P , W _P ... Are corrected. As a result, each tracking window W _P , W _P ... Is detected as a road surface detection window W _R , W _R.
It becomes possible to make correction so that it is directly above the road surface detected in. Further, with the correction value S ₂ , the road surface detection window W
The upper and lower positions of _R , W _R ... May be corrected.

As still another embodiment of the present invention, the relative velocity obtained based on the tracking windows W _P , W _P ... In the second embodiment is V _n1 and the tracking windows W _P , W _P
... and the relative speed of the road surface detection windows W _R , W _R ...
And _{Rn, | V n1 -V Rn |} < when was the constant value, based on the road surface detection window W _R, W _R ... the relative speed based on the near relative speed based on the tracking window W _P, W _P ... It is also possible to determine that upward pitching has occurred in the host vehicle and correct the tracking windows W _P , W _P ... To the lower side.

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.

For example, in the above embodiment, when the pitching change detecting means 11 detects a pitching change exceeding the set value, the window position correcting means 14 corrects the vertical position of the window determined by the window determining means 7. The position of the window determined by the window determining means 7 is fixed, but it is also possible to substantially correct the window position by invalidating the image signal above or below the window. . It is also possible to directly detect the pitching of the vehicle. Further, based on the distance data obtained by the distance calculation means 9, either the relative velocity with respect to the object 4 or the relative acceleration / deceleration is obtained by the relative momentum calculation means 12, and either the relative velocity or the relative acceleration / deceleration is obtained. The pitching determination means 13 may determine that a pitching change of a predetermined amount or more has occurred when one of them changes so as to satisfy a predetermined condition.

[0037]

As described above, according to the invention described in any one of claims 1 to 4, when the pitching of the own vehicle occurs, the upper and lower sides of the window set to obtain the distance to the object. The position is corrected substantially, and the distance to the object can be accurately measured even if pitching occurs.

[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 window arrangement.

FIG. 4 is a diagram showing a window arrangement of a second embodiment.

FIG. 5 is a diagram showing a conventional window arrangement.

FIG. 6 is a diagram for explaining a problem caused by pitching.

[Explanation of symbols]

2A, 2B ... Optical system 3A, 3B ... Image sensor 4 ... Target 7: Wind determination means 8: Correlation calculation means 9: Distance calculation means 11 ... Pitching change detection means 12 ... Relative momentum calculation means 13 ... Pitching determination means 14 ... Window position correcting means

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-96525 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01C 3/06 G01B 11/00 G06T 1 / 00 280 G08G 1/16

Claims (4)

(57) [Claims] 1. A pair of optical systems (2A, 2B), a pair of image sensors (3A, 3B) for respectively forming images from the optical systems (2A, 2B), and both image sensors (3A, 3B). 3B) The window determining means (7) for determining the windows of the pair of images formed on the image is compared with the image signal in the window determined by the window determining means (7) to determine the deviation amount from the optical axis of both images. A distance calculation for calculating the distance to the object (4) by executing a calculation based on the principle of triangulation using the correlation calculating means (8) for detecting and the shift amount obtained by the correlation calculating means (8). In a vehicle distance measuring device including means (9), a relative distance between the object (4) and at least one of relative acceleration / deceleration is calculated based on the distance data obtained by the distance calculation means (9). With momentum calculation means (12) Pitching determination means for determining that a pitching change of a predetermined amount or more has occurred when at least one of the relative speed and the relative acceleration / deceleration obtained by the relative momentum calculation means (12) changes so as to satisfy a predetermined condition ( 13) and window position correction means (14) for substantially correcting the vertical position of the window in response to the pitching determination means (13) determining that a pitching change of a predetermined amount or more has occurred. Distance measuring device for vehicles. 2. The pitching determination means (13) is configured to determine that a pitching change of a predetermined amount or more has occurred when the sign of the relative velocity obtained by the relative momentum calculation means (12) is inverted. the features of claim 1
The vehicle distance measuring device described. 3. A pitching change of a predetermined amount or more occurs when the absolute value of the relative acceleration / deceleration obtained by the relative momentum calculation means (12) exceeds a set value by the pitching determination means (13). The vehicle distance measuring device according to claim 1 , wherein the distance measuring device is configured to make a determination. 4. The window determining means (7) is an object.
Tracking window (W _P ) to determine the distance to (4 )
And a road surface inspection provided below the tracking window (W _P ).
The knowledge window (W _R ) is set, and the pitching determination means (13) sets the road surface detection wheel.
The relative velocity based on the wind (W _R )
Upward to the vehicle based on the fact that it is close to the relative speed based on _P )
Characterized by determining that the pitching of the
The vehicle distance measuring device according to claim 1, 2, or 3.