JP3099691B2 - Object position measurement method on traveling road - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly mounted on a vehicle such as an automobile, and uses a single-lens CCD camera to increase the distance from a vehicle to an object on its traveling path without being affected by irregularities on the road surface. It relates to a method of measuring with accuracy.

[0002]

One of the methods proposed for measuring the distance between a vehicle, especially an object, that is, an object, on a traveling path of a vehicle is disclosed in Japanese Unexamined Patent Publication No. Hei.
No. 273500.

In this technique, a vehicle is detected by extracting a horizontal edge component in a traveling path detected by a video camera by a preceding vehicle detecting means (14), and an inter-vehicle distance detecting means (1) is detected.
According to 5), the distance to the preceding vehicle (object) is detected using the length of the horizontal edge component detected by the preceding vehicle detecting means (14) from the lower end of the image.

However, in such a conventional measuring method, the inter-vehicle distance is measured based on the vertical length from the lower end of the captured image of the preceding vehicle (object).
It has sufficiently high measurement accuracy on flat roads, but when the height of the camera mounting ground and the camera mounting angle change due to uneven roads, the measurement accuracy is significantly reduced because these factors are not considered. descend.

SUMMARY OF THE INVENTION It is an object of the present invention to measure the position of an object with high accuracy even on roads having any height difference by enabling the distance to the object to be measured in consideration of the unevenness of the road even when the road is uneven. It is to provide a measurement method that can be performed.

[0006]

SUMMARY OF THE INVENTION The present invention provides the following: (1) To accurately measure the position of an object in consideration of a variation in the ground clearance at which a camera is mounted due to irregularities on a road surface, etc. And the length (h) in the vertical direction up to the entire width are detected, and the mounting ground height (t) is obtained from these values and the actual road width (W), and this mounting ground height (t) is used. To measure the object position (L). (2) In order to accurately measure the position of the target object in consideration of the effect of camera tilt such as the effect of pitching, the position (l∞) of the road vanishing point (N) on the image is detected and attached. The angle (θ) is obtained, and the object position (L) is measured from the mounting angle (θ) and the length detection value (l) to the object on the image. The first technical means is that, when a monocular camera captures an image of a road in front of or behind a vehicle and measures the distance to an object on the road, the total width of the road is determined. The overall width (w) of the road on the captured image (10) and the vertical length (h) from the base line of the image (10) to the position of the full width (w) are detected, and the overall width of the road on the image ( w), the height in the vertical direction (h), and the actual road width (W), after obtaining the ground clearance (t) of the camera, the ground clearance (t) of the camera mounting;
The distance to the object is measured based on the length (l) from the base line of the image (10) to the object (20) and the focal length (f) of the camera.

[0007] More specifically, in the first means,
The mounting ground height (t) and the distance to the object (L) are calculated by the following equations.

T = {(V / 2) -h} (W / w)

L = (t × f) / {(V / 2) −1}

Where V = length of the image in the vertical direction f = focal length of the camera lens l = length from the base line to the object on the image

Therefore, according to the first means, even if the height (t) of the camera changes due to irregularities on the road or the like, the height (t) can be corrected and the distance (L) to the object can be measured. Thus, it is possible to accurately measure the position of the object even on roads having any height difference.

In this case, the vertical length (h) from the base line of the image (10) to the position of the full width (w) and the image (1)
0) It is also possible to set the length (l) from the base line to the object (20) to be the same. This configuration simplifies measurement and calculation processing,
Since the measurement data of the mounting ground height (t) and the measurement data of the distance (L) to the object are synchronized, the measurement ground height (t) is not affected by the fluctuation of the mounting ground height (t) due to the traveling of the vehicle. The object position can be measured.

[0013] A second technical means is to use a monocular camera to image the road ahead or behind the vehicle and measure the distance to an object on the road.
The vertical length (l∞) of the vanishing point (N) on the road from the image (10) baseline on the image (10) is detected, and the length (l∞) to the vanishing point and the camera's The mounting angle (θ) of the camera is determined based on the focal length (f), and then the entire road width (w) on the image (10) and the distance from the base line on the image (10) to the entire road width (w). A ground height (t) for mounting the camera is obtained based on the length (lw) in the vertical direction, an actual road width (W), and the mounting angle (θ), and then the mounting angle (θ) and the mounting ground height are obtained. Measuring the distance (L) to the object (20) based on (t) and the vertical length (l) from the image (10) baseline to the object (20); In the position measurement method.

More specifically, in the second means, the camera mounting angle (θ), the mounting ground height (t), and the distance to the object (L) are calculated by the following equations.

Θ = tan ⁻¹ [(l∞−V / 2) / f] t = [fsin θ + ｛(V / 2) −lw｝ cos θ] × (W / w)

L = ([fcos θ − {(V / 2) −l｝ sin θ] /
[Fsinθ + ｛(V / 2) −1｝ cosθ]) × t where V = length of image (10) in the vertical direction f = focal length of camera (1)

Therefore, according to the second technical means, even if the camera is tilted due to the pitching of the vehicle or the like, it can be corrected and the distance (L) to the object can be accurately measured. .

In the second means, preferably, the road vanishing point (N) in the image (10) is linearly approximated to white line images on the left and right of the actual road image on the image (10), respectively. It is preferable to measure the intersection of the two approximate straight lines to obtain it.

According to this method, the road vanishing point (N) can be accurately obtained by a simple method.
The mounting angle (θ) of the camera can be accurately measured.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. However, unless otherwise specified, the dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention thereto, but are merely illustrative examples. Absent.

FIG. 1 is a block diagram showing the configuration of a system for measuring the position of an object on an automobile traveling route according to the present invention. FIG. 2 is a configuration diagram of an image of the traveling route according to the first embodiment of the present invention. It is a schematic diagram of object position measurement.

In FIG. 1, reference numeral 1 denotes a monocular camera which is constituted by a CCD sensor. Reference numeral 3 denotes an image processing device for performing processing for connecting an image of the camera 1 to a calculation device (CPU) to be described later or display processing, and reference numeral 5 denotes a calculation device (CP) for obtaining required measurement data such as a position of an object on a traveling road.
U), 6 are input / output storage devices (RAM) for storing various data, 7 is an output-only storage device (ROM) for storing operation programs, 2 is a display device for displaying calculation or measurement results, and 4 is This is a system bus that performs data transmission between the above elements.

Referring to FIGS. 2 to 3, a first embodiment of the method of measuring the position of an object on the traveling path of the automobile configured as described above, taking into account the variation in the ground clearance at which the camera is mounted, will be described. This will be described below.

The actual road image taken by the CCD camera 1 is input to the image processing device 3. In the image processing device 3, as shown in FIG. 2, white lines 11a and 11b on the left and right of the actual road image 11 are drawn as bitmap data corresponding to CCD pixels on an image RAM in an image 10 of the camera 1. By counting the bitmap, the lengths of the various data areas in the vertical and horizontal directions can be measured.

FIG. 2 shows an image 10 developed on the image RAM.
, W is the full width of the actual road image 11 on which the object 20 to be measured is drawn on the image 10, and h is the vertical length from the base line at the lower end of the image 10 to the position of w. Here, l is the vertical length from the lower end to the object 20.

FIG. 3 shows a lens 1 of the camera 1.
The length A of the object 200 at a distance of L from 9 is represented by Expression 1.

[0027]

(Equation 1)

Here, if A is considered to be the road width (constant value), the proportional expression (1) is established. t = {(V / 2) −h} (W / w) (1) where t = height of the camera 1 above the ground V = vertical length of the entire area of the image 10 f = lens for the camera 1 19 focal lengths

Therefore, the road width w on the actual traveling road image 11 in the image 10 shown in FIG.
Is measured, the length V in the vertical direction of the image 10 and the actual road width W are known.
From equation (1), the height t above the camera 1 above the ground can be calculated.

Next, referring to FIG. 3, the set point of the camera 1, that is, the actual travel distance L from the vehicle to the object 20 (corresponding to the object 20) is expressed by the following equation.

L = t × (f / (V / 2−1)) (2)

Therefore, for each traveling road image 10, a road width w that is the full width of the actual traveling road image 11 drawn on the traveling road image 10,
By measuring the vertical length l from the image base line up to (1) to the object, and obtaining the mounting ground height t of the camera 1 by the equation (1), the calculated mounting ground height t is Image 10
The value takes into account the unevenness of the road surface of the road represented by

Then, by substituting this t into the equation (2), and calculating the distance L from the vehicle to the object 20, this L becomes
It represents the distance to the target object in consideration of a change in the ground height t at which the camera 1 is mounted due to irregularities on the road. FIG. 4 shows a flowchart of the measurement and calculation of the distance L to the object 20 by the above method. That is, in the figure, an image on the road in front or behind is captured by a monocular CCD camera, and the CCD image is stored in an image RAM by an image processing device.
It is drawn as bitmap data corresponding to D pixels, w and h are measured by counting the bitmap, and the height t above the camera mounting ground is calculated by the above equation (1).

Next, after counting the bitmap data in the image RAM and measuring the vertical length l from the base line on the image to the object, the distance L to the object is calculated by the above equation (2). Is calculated.

When measuring the distance L to the object 20, the vertical length h to the position of the road width w on the image 10 is the same as the distance l to the object. Can also be set to According to this configuration, the measurement data of the camera mounting ground height t and the measurement data of the distance L are synchronized, so that even if the mounting ground height t fluctuates as the vehicle travels, the influence thereof is not affected. Without this, the distance L can be measured accurately. Therefore, according to the above embodiment, the height (t) of the camera due to the unevenness of the road
Can be corrected and the distance (L) to the object can be measured, so that the position of the object can be accurately measured on any road with a height difference. If there is pitching, etc., accurate measurement cannot be performed.

The second embodiment is an improvement on this point, and a measuring method taking into account the inclination of the camera due to the pitching of the vehicle will be described with reference to FIGS. In FIG.
An image 10 captured by the camera 1 and input to the image processing device 3 is shown. In FIG. 5, it is an actual running road image of a flat road that curves to the right, and 11a and 11b are left and right white lines of the running road.

Further, w is an actual road image 11 on the image 10.
The road width is the entire width corresponding to the actual road width w above, and lw is the distance from the lower end of the image 10 to w.

On the other hand, FIG. 6 is a schematic diagram showing the positional relationship between the image 10, the object 20, and the lens 19 when the lens 19 of the camera 1 is inclined at an angle θ from the horizontal line Y due to the effect of pitching. . In FIG. 6, when the lens 19 is tilted by the mounting angle θ, the camera 1
The distance L to is represented by the following equation (3).

L = ([fcosθ − ｛(V / 2) −1｝ sinθ] / [fsinθ +
｛(V / 2) −l｝ cos θ]) × t (3) In equation (3), if the distance to the vanishing point of the road, that is, L = ∞,

L = V / 2 + ftan θ (4) The emission l−V / 2 = ftan θ, where l is l∞ (l∞: length to the vanishing point of the road), and the mounting angle θ of the camera 1 Is as follows: θ = tan ⁻¹ {[ ^l } ⁻ (V / 2)] / f} (5)

Here, V = the vertical length of the image 10 f = the focal length of the lens 19 1 = the vertical length from the image base line Therefore, if the road vanishing point N (infinity) is measured for each image 10 , V and f are known, so that according to equation (5),
The mounting angle (tilt angle) θ of the camera can be obtained.

Next, the road vanishing point (infinity) N is as follows.
Ask for it. On the image 10 shown in FIG.
Left and right white at positions very close to the own vehicle in the actual road image 11
Each of the points on the lines 11a and 11b is about three points or more (FIG.
A₁, A_Two, A_ThreeAnd b₁, B_Two, B_ThreeA) measure these
Point a₁, A_Two, A_Three, B₁, B_Two, B 3 by the least squares method
Each is approximated by a straight line. Linear approximation as described above
The intersection N between the left and right straight lines 12a and 12b is the road vanishing point N (no
Infinity).

Next, in FIG. 5, the relationship between the road width w on the image 10 and the actual road width W corresponding thereto is as follows.

[0044]

(Equation 2)

Substituting equation (3) into equation (2) and rearranging it,

W = [t / (fsinθ + ｛(V / 2) −1w｝ cosθ)] × w (7) Therefore, since the road width W is constant,

T = [fsin θ + ｛(V / 2) −lw｝ cos θ] × (W / w) (8)

Therefore, the length lw from the position of the road widths w and w on the image 10 to the base line (lower end) of the image 10 is measured, and the inclination angle θ of the camera obtained by the above equation (5) is used. Thus, the camera-mounted ground clearance t can be obtained by equation (8).

Then, the distance L from the camera 1 to the object
Is calculated by the above equation (3) using the camera mounting ground height t calculated by the above equation (8) while measuring the length l to the target object 20 on the image 10.

FIG. 7 is a flowchart showing the procedure for measuring the actual angle L from the camera 1 (own vehicle) to the object 20 using the mounting angle: θ, the mounting ground height: t, and the aforementioned θ and t. Show. That is, an image on the road in front or behind is captured by a monocular CCD camera in the same figure, and the image is processed and displayed by an image processing device. Three or more points on the left and right white lines 11a and 11b on the base line side on the image are measured, and the right and left measurement points are approximated by a straight line using the least squares method.

Left and right straight lines 12a and 12b approximated by straight lines
The road vanishing point N is measured from the intersection of. After finding the road vanishing point N, the camera attachment angle θ is calculated by the above equation (5). Next, after measuring the road width w on the image and the distance lw to the w, the camera attachment height t is calculated by the equation (8). Finally, the distance L to the object is calculated by the equation (3) using the above θ and t.

Thus, even if the camera is tilted due to the pitching of the vehicle or the like, the distance L to the object can be accurately measured in consideration of the inclination.

[0053]

The present invention is configured as described above.
According to the first aspect of the present invention, the total road width (w) on the image and the vertical length (h) up to the full width are detected, and the mounting ground clearance is calculated based on these values and the actual road width (w). (T)
Since the position (L) of the object is measured using the ground clearance (t), even if the height (t) of the camera changes due to unevenness of the road or the like, this is corrected and the distance to the object is corrected. Since (L) can be measured, the position of the target object can be accurately measured even on roads having any height difference.

According to the second aspect of the present invention, in addition to the above, the measurement and calculation processing are simplified, and the measurement data of the mounting ground height (t) and the distance (L) to the object are measured. Since the data is synchronized with the application data, the effect that the position of the object can be measured without being affected by the variation of the mounting ground height (t) due to the running of the vehicle is superimposed.

According to the third aspect of the present invention, the position (l∞) of the road vanishing point (N) on the image is detected, thereby obtaining the mounting angle (θ). Since the object position (L) is measured from the length detection value (l) to the object on the image, even if the camera is tilted due to pitching of the vehicle or the like, this is corrected by analyzing the image and the object is corrected. Distance (L) can be accurately measured.

According to the fourth aspect of the present invention, in addition to the above, the road vanishing point (N) can be accurately obtained by a simple method, whereby the mounting angle (θ) of the camera can be determined with high accuracy. Can be measured.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a system for measuring the position of an object on an automobile traveling road according to first and second embodiments of the present invention.

FIG. 2 is a configuration diagram of a traveling road image according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of calculating an object distance according to the first embodiment of the present invention.

FIG. 4 is a measurement flowchart according to the first embodiment of the present invention.

FIG. 5 is a configuration diagram of a traveling road image according to a second embodiment of the present invention.

FIG. 6 is an explanatory diagram of calculating an object distance according to the second embodiment.

FIG. 7 is a measurement flowchart according to the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Camera 3 Image processing device 5 Computing device (CPU) 10 Image 20 Object 11 Actual traveling road image L Distance to object t Camera mounting ground height θ Camera mounting angle

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ Identification code FI G08G 1/16 G08G 1/16 C H04N 7/18 H04N 7/18 C (56) References JP-A-3-273500 (JP, A) JP-A-1-242916 (JP, A) JP-A-64-66712 (JP, A) JP-A-5-183784 (JP, A) JP-A-7-120258 (JP, A) JP-A-64 -15605 (JP, A) JP-A-6-229759 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 3/00-3/32 G01C 5/00 G01B 11/00 B60R 21/00

Claims (4)

(57) [Claims] An object position measuring method for measuring the distance to an object on a road by capturing the entire width of a road in front of or behind a vehicle using a monocular camera, wherein the captured image (10) captures the entire width of the road. , And the vertical length (h) from the baseline of the image (10) to the position of the full width (w) is detected, and the total width (w) of the road on the image and the vertical length are detected. Sa (h)
After obtaining the camera mounting ground height (t) based on the actual road width (W) and the camera mounting ground height (t), the camera mounting ground height (t) and the image (10) from the base line to the object (20) are obtained. A method for measuring a position of an object on a traveling path, comprising measuring a distance to the object based on a length (l) and a focal length (f) of the camera. 2. A vertical length (h) from the base line of the image (10) to the position of the full width (w) and a length (l) from the base line of the image (10) to the object (20). The object position measuring method according to claim 1, wherein the object position is set to be the same. 3. A method for measuring the distance to an object on a road by capturing an image of a road ahead or behind the vehicle with a single-lens camera, comprising: a vanishing point on the road on an image (10) obtained by the camera; (N) detecting a vertical length (l∞) from the baseline of the image (10), and based on the length (l∞) to the vanishing point and the focal length (f) of the camera, Is determined, then the overall width (w) of the road on the image (10), the vertical length (lw) from the baseline on the image (10) to the overall width (w) of the road, An installation ground height (t) of the camera is obtained based on the actual road width (W) and the installation angle (θ). Then, the installation angle (θ), the installation ground height (t), and the image (10) baseline Object (20) based on the vertical length (l) from the object to the object (20) Measuring the distance (L) to a target object on a traveling path. 4. A road vanishing point (N) in the image (10) is linearly approximated to left and right white line images of an actual road image (11) on the image (10), and an intersection of both approximate straight lines is determined. 4. The method for measuring the position of an object on a traveling path according to claim 3, wherein the position is obtained by measurement.