JPH08184433A - Method for measuring grade of traveling path - Google Patents

Abstract

PURPOSE: To measure the up/down slope of a traveling path accurately from an actual image thereof being picked up by means of a camera. CONSTITUTION: On the screen 10 of a CCD camera installed on the front of a vehicle, up/down slope of a traveling path is detected in the vicinity of a reference point and the grade is measure approximately based on the vertical lengths h1, h2, h3 and h4 between reference points p1, p2, p3 and p4 on the left end line 13 of the actual image 12 of traveling path and the left end line 14 of the model image 11 of a straight flat road, and the vertical lengths 11, 12, 13 and 14 between the reference points p1, p2, p3 and p4 and the lower end of the screen 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the condition of vertical gradient on a traveling path of a vehicle.

[0002]

2. Description of the Related Art In a conventional roadway recognition apparatus, as shown in Japanese Patent Application Laid-Open No. 4-138505, a mask image stored in a mask storage unit and an actually obtained roadway image are recorded. If the apex of the road image is above the apex of the mask image, it is recognized that the apex of the road is uphill, and the apex of the road image is below the apex of the mask image. For example, the road is configured to be recognized as a downhill, but it is difficult to improve the measurement accuracy because the vertical gradient of the road is measured only by the positional relationship of the vertices. If the apex of is hidden by a traveling vehicle or the like in front, there is a problem that the above measurement cannot be performed.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to reliably measure the condition of the vertical gradient on the traveling road from the traveling road image obtained by the camera.

[0004]

In order to achieve this object, the method of measuring the gradient of a road according to the present invention compares a road image obtained by a camera and a road model image on their side edges. Then, the deviation between the two images in the vertical direction on the screen is detected, and the condition of the vertical gradient on the traveling path is measured by the deviation between the two images.

[0005]

That is, the deviation between the two images in the vertical direction is detected by comparing the running road image and the running road model image on the side edge line, and the condition of the vertical gradient on the running road is measured based on the deviation between the two images. Therefore, the measurement can be performed continuously at all times, and it is possible to reliably measure the condition of the vertical gradient on the traveling road. Also, by appropriately setting the measurement point, the traveling vehicle in front, etc. The measurement can be carried out without being disturbed.

[0006]

Embodiments of the present invention shown in the drawings will be specifically described below. In FIG. 1, the stereo camera 1 is
It has two CCD cameras arranged in the upper and lower parts of the front of the vehicle, respectively, facing the front of the vehicle.
Is connected to the image processing controller 3, and the clock terminal 4 of the stereo camera 1 is connected to the image processing controller 3.
It is connected to the.

In the image processing controller 3, as shown in FIG. 2, a front straight flat road model image 1 corresponding to the mounting position of each CCD camera is displayed on the screen 10 of each CCD camera.
1. That is, since the traveling road is a straight flat road, an image that linearly converges to the center corresponding to the distance from the front of the vehicle can be obtained, and a real image of the front traveling road taken by the CCD camera. 12 is overlapped and carved, and in this case, if the road surface is flat, the length from the lower end of the screen 10 to the upper side represents the actual horizontal distance from the vehicle to the front.

On the screen 10, four appropriate reference points p1 and p on the white line 13 on the left end of the actual road image 12 are displayed.
2, p3, p4 and these reference points p1, p2, p3,
The vertical lengths of the vertical lines passing through p4 and the points q1, q2, q3, and q4 intersecting the left end white line 14 of the model image 11 that is a straight line inclined to the upper right are respectively h1,
h2, h3, h4, and each point q1, q2, q3,
The vertical lengths of q4 and the bottom of the screen 10 are l1 and l, respectively.
2, 13, and 14.

On the other hand, as shown in FIG.
V: vertical length of the whole screen 10 f: vertical length of the entire screen 10, f: focal length of the lens 17 in the CCD camera, h: vertical image 15 Vertical length L: Actual horizontal distance from the lens 17 to the real image 16 t: Mounting height of the lens 17 on the road surface l: Vertical length from the upper end of the screen 10 to the vertical image 15 H: Vertical distance of the real image 16 , The following equation holds. H = L / f × h = t / (V / 2−1) × h (1)

Therefore, by using the equation (1),
The above vertical lengths h1, h2, h3, h on the screen 10
4 can be converted into actual vertical distances H1, H2, H3, H4, respectively. In addition, from the front surface of the vehicle equipped with the stereo camera 1, the reference points p1, p on the screen 10
Actual horizontal distances L1, L2, L3, L to respective points on the actual left end white line corresponding to 2, p3, p4, respectively.
4 is measured from the vertical lengths l1, l2, l3, and l4 on the screen 10, respectively, by a distance measuring sensor based on the stereo image of the stereo camera 1, or is measured in advance from a straight flat road model. It is something that can be kept.

Next, as shown in FIG. 4, L-H
On the plane, point P1 (L1, H1), point P2 (L
2, H2), point P3 (L3, H3), point P4 (L4, H
4) is plotted respectively and each point P1, P2, P3, P
If the approximate straight line S passing through 4 is drawn by the method of least squares and the approximate straight line S is H = α (L−β) (2), the gradient angle θ of the traveling road can be approximately obtained by the following equation. it can. tan θ = α (3)

That is, if θ> 0, the traveling road is at points P1 to P1.
It is determined that the point corresponding to the point P4 is an uphill with a gradient angle θ, and if θ <0, the traveling path is a point with a gradient angle θ at a point corresponding to the points P1 to P4, and if θ≈0. It can be determined that the traveling road is a substantially flat road at points corresponding to the points P1 to P4.

If H = 0 in the equation (2), L = β (4) That is, it can be estimated that the gradient of the road starts from a distance of approximately β in front of the vehicle.

From the above, it is possible to easily estimate which of the upper and lower slopes appears on the traveling road at the points on the traveling road corresponding to the points P1 to P4 or whether the traveling road is a substantially flat road. At the same time, when one of the upper and lower slopes appears on the traveling road, the slope can be quantitatively calculated, so that the condition of the traveling road ahead can be accurately grasped.

Further, since these measurements can be performed instantaneously, it is possible to facilitate the driving of the vehicle on the road, and at the same time, the above-mentioned measurement is performed by the upper and lower two CCD cameras on the front surface of the vehicle. Therefore, there is an advantage that the accuracy can be easily improved.

In the above embodiment, four reference points are set on the left end line of the actual road image on the screen of the CCD camera to detect the vertical gradient of the road and measure the magnitude of the gradient. However, selecting more reference points, for example,
If the vertical gradient is measured in the same manner as described above for a plurality of sections with one section for every four consecutive reference points, each continuous gradient change can be instantaneously measured even on a traveling road that repeats going up and down. it can.

In each of the above embodiments, the reference points are set on the left end line of the actual road image on the screen of the CCD camera, but they are set on the left end line of the straight flat road model image. Taking the reference points, detecting the vertical length from each of the reference points to the left end line of the actual road image, and performing the same processing as the above embodiment, the same effect as the above embodiment Alternatively, the same action and effect can be obtained even if the right end line of the traveling path is used instead of the left end lines.

Further, a single CCD camera may be used, or the CCD cameras may be arranged on the left and right sides of the front of the vehicle to perform the same treatment as in the above embodiments. Needless to say, it is better to install the car at the highest position on the front of the vehicle to improve the measurement accuracy.

[0019]

According to the method for measuring the gradient of a traveling road according to the present invention,
Since the deviation between the two images in the up-and-down direction is detected by comparing the running path image and the running path model image on the side edge line, the condition of the vertical gradient on the running path is measured based on the deviation between the two images. It is possible to always reliably measure the condition of the vertical gradient on the traveling road, and by setting a large number of measurement points, it is possible to carry out the measurement without being disturbed by a traveling vehicle in front of the traveling road. The situation of can be grasped accurately.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is an image diagram of the above embodiment.

FIG. 3 is a measurement explanatory diagram of the above-described embodiment.

FIG. 4 is an explanatory diagram of measurement in the above embodiment.

[Explanation of symbols]

 1 stereo camera 3 image processing controller 10 camera screen 11 straight flat road model image 12 actual image p reference point q intersection point h vertical length l vertical length L actual horizontal distance H vertical distance

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Claims (6)

[Claims] 1. A roadway image obtained by a camera and a roadway model image are compared on their side edges to detect a vertical deviation between the two images on a screen, and a deviation between the two images is detected. A method for measuring the gradient of a running road by measuring the vertical slope condition on the above running road. 2. The roadway slope measuring method according to claim 1, wherein the deviation between the two images is detected at a plurality of positions in the left-right direction on the screen. 3. The vertical direction on the screen according to claim 1 or 2, wherein a reference point is set on the travel road image or the travel road model image, and the deviation between the images passes through the reference point on the screen. A roadway slope measurement method that detects deviations from deviations. 4. The method according to claim 1, wherein the starting point of the deviation between the two images is detected.
A traveling road gradient measuring method for measuring the starting point of the vertical gradient on the traveling road. 5. The traveling road gradient measuring method according to claim 1, wherein the traveling road model image is a straight road model image or a straight flat road model image. 6. The deviation between the two images according to claim 1, wherein the deviation between the two images is detected from a left end line image or a right end line image of the traveling road image and the traveling road model image, respectively. Road slope measurement method.