JP2971693B2 - 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 an optical distance measuring apparatus using an image sensor, and more particularly to a distance measuring apparatus for continuously measuring an inter-vehicle distance between a preceding vehicle and a host vehicle.

[0002]

2. Description of the Related Art Conventionally, an optical distance measuring device using a video camera is disclosed in Japanese Patent Publication No. 63-38505 and Japanese Patent Publication No. 63-46363. FIG. 6 is a block diagram showing the configuration of the distance measuring device disclosed therein. This distance measuring device has two optical systems provided above and below, and has lenses 1 and 2 arranged apart from each other by a base length L, and a focal length f behind these lenses 1 and 2.
, And a signal processing device 6 that calculates the distance to the object 5 using the image signals sent from the image sensors 3 and 4.

In the above arrangement, the lenses 1 and 2 and the image sensors 3 and 4 are respectively provided in a pair at the top and bottom.
It is constituted by video cameras 20 and 21.

Next, the principle of measuring the distance to the object 5 will be described. The image signals of the object 5 formed on the image sensors 3 and 4 through the lenses 1 and 2 constituting the video cameras 20 and 21 are respectively superposed while being sequentially shifted by the signal processing device 6 by the signal processing device 6. The distance R from the shift amount n when the two image signals best match with each other to the object 5 is obtained by the equation (1) based on the principle of triangulation.

R = f × L / n (1)

In this case, a pair of video cameras 20, 21
Are video cameras that form one image by using the image signal of the first field and the image signal of the second field, respectively. A pair of upper and lower images used by the signal processing device 6 for distance measurement is a video camera 20. , 21 are one combined image formed from the image signal of the first field and the image signal of the second field. That is, the signal processing device 6
Captures a first field image signal from each of the two video cameras 20 and 21 into a built-in memory (not shown), then captures a second field image signal, and forms one composite image composed of the two image signals. The distance to the target object 5 is obtained using the above.

[0007]

As described above, the conventional distance measuring device measures the distance by using the composite image of the image of the first field and the image of the second field. After the image is captured, if a temporary disturbance enters the image due to vibration of the video camera or a wiper before the image signal of the second field is captured, the contrast of the image deteriorates, and the correlation with the reference image is reduced. Was sometimes impaired. Therefore, there is a problem that the measured value of the distance changes suddenly, and the measured value includes a large error.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to eliminate the influence of the capture time difference by comparing images using only image signals captured in a short time, thereby improving reliability. The purpose is to perform high distance measurements.

[0009]

According to a first aspect of the present invention, there is provided a distance measuring apparatus which uses a video signal of a pair of video cameras only in a first field or only a second field of a video signal. The distance is measured based on the distance.

A distance measuring apparatus according to a second aspect of the present invention is based on the principle of triangulation by using only a first field image signal or a second field image signal of a pair of video cameras alternately. The distance is measured based on the distance.

[0011]

According to the distance measuring apparatus of the present invention, since the image signal captured by the video camera is only the first field image or only the second field image, the image signal to be processed is shortened. It can be captured in about half the time (about half of conventional).

Further, according to the distance measuring apparatus of the present invention, the image signals captured by the video camera are only the image signals of the first field of the corresponding upper and lower video cameras or the image signals of the second field. Since only the signals are used alternately, image signals can be captured in a short time as in the case of the first aspect.

[0013]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1 in a case where the inter-vehicle distance to a preceding vehicle is measured.
As shown in FIG. 1, a distance measuring device according to the present invention includes lenses 1 and 2 provided above and below, separated by a base line length L,
Two-dimensional image sensors 3 and 4 are provided corresponding to the lenses 1 and 2, respectively. The lenses 1 and 2 and the image sensors 3 and 4 are provided in the same manner as in the related art.
It is composed of two video cameras 20 and 21 provided in a pair at the top and bottom.

The distance measuring device is connected to image sensors 3 and 4 of two video cameras 20 and 21, respectively, and analog-to-digital converters 7 and 8 for converting an analog signal to a digital signal; Memories 9, 10 connected to digital converters 7, 8, respectively
And a microcomputer 11 connected to the memories 9 and 10, and connected to the microcomputer 11 and the memories 9 and 10 and controlled by the microcomputer 11 to display an image captured by the upper image sensor 3. A display 12, a window setting device 13 connected to the display 12 and connected to the microcomputer 11 for setting a window for specifying a preceding vehicle 5 </ b> A as an object of distance measurement on an image, and a window setting device 13. Image tracking instruction switch 1 connected to setting device 13 and operated by the driver
4 is provided.

In the above configuration, for example, as shown in FIG. 2, a preceding vehicle 5A to follow the image of the upper image sensor 3 enters, and as shown in FIG. 5A is captured, and the distance to the preceding vehicle 5A is measured. This distance measurement will be described below.

First, the microcomputer 11 reads out the pixel signal in the window 15 from the memory 9 and uses it as a reference image signal for distance calculation. The area corresponding to the window 15 in the memory 10 in which the image signal of the lower image sensor 4 is stored is stored in the microcomputer 11.
Select. The microcomputer 11 calculates the sum of the absolute values of the signal differences between the upper and lower pixels while sequentially shifting the image signal of the memory 10 by one pixel with respect to the reference image signal. That is, the position of the image that matches the image within the window 15 is determined while sequentially shifting it one pixel at a time. At this time, the area in the memory 10 involved in the calculation is a window 1 as shown in FIG.
The area 16 corresponds to the position 5. As described above, the upper and lower pixels are compared, and the shift amount of the pixel when the sum of the absolute values of the difference signals is minimum is n pixels, the pitch of the pixels is p, the base line length L of the optical system, the lens 1, Assuming that the focal length of 2 is f, the distance R to the preceding vehicle 5A can be obtained by the following equation (2), and the distance to the preceding vehicle 5A in the window can be measured as described above.

R = f × L / (n × p) (2)

Next, as a means for taking in an image, only the first field image is taken in.
3 and 4 will be described with respect to a case where only the field is used. That is, in the conventional distance measuring device, the image comparison is performed using the composite image of the first field image and the second field image. However, in the first embodiment, the distance is measured using only one side field image. Here, FIG. 3 shows an image of the first field, and FIG. 4 shows an image of the second field at this time. FIG. 4 shows a state in which the video cameras 20 and 21 vibrate after capturing the image signal of the first field, and the image of the preceding vehicle 5A bounces upward. In such a case, in the present invention, image comparison is performed using only one side field (first field), and an image signal is captured in a short time that is approximately half or less of that of the related art, so that it is not affected by vibration.

Embodiment 2 FIG. The first embodiment includes a first field,
Alternatively, the case where the distance measurement is performed using only the image signal of one field of the second field has been described, but the present invention can also be achieved by alternately using the image signal of the one field. Hereinafter, FIG. 5 will be described with such a configuration as a second embodiment. FIG. 5 is a flowchart illustrating a processing procedure according to the second embodiment.

First, in step S1, the capture of the image signal of the first field is started. In step S2, while capturing the image signal of the first field, the image signal of the second field captured previously is compared.
In step S3, the distance is measured.

If the capture of the image signal of the first field is completed in step S4, then in step S5 the second
Start capturing the image signal of the field. In step S6, while the image signal of the second field is fetched, the image signal of the first field fetched last time is compared, and the distance is measured in step S7. Step S8-
In S12, processing is performed using the same procedure as described above. As described above, the distance is measured by alternately comparing only the image signal of the first field and comparing only the image signal of the second field.

According to the above configuration, the time required to capture the image signal is shortened, and continuous distance measurement is possible. Therefore, it is possible to quickly respond to sudden changes in distance, and to obtain accurate distance data.

[0023]

As described above in detail, according to the distance measuring apparatus of the first aspect of the present invention, only the image signal of the first field or only the image signal of the second field of the pair of video cameras is used. The distance measurement is performed based on the principle of triangulation, so that stable distance measurement can be performed without being affected by temporary disturbance between fields caused by camera vibration or wiper operation. At the same time, the processing time can be shortened.

According to the distance measuring apparatus of the second aspect of the present invention, the triangulation of the pair of video cameras is performed using only the first field image signal or only the second field image signal. Since the distance measurement is performed based on the principle, a stable distance measurement can be performed without being affected by a temporary disturbance between fields caused by camera vibration or a wiper operation, similarly to the effect of claim 1. In addition to this, there is an effect that the processing time can be shortened.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a first embodiment.

FIG. 2 is a diagram showing an image for explaining the operation of the first embodiment.

FIG. 3 is a diagram illustrating an image of a first field of an image that is updated this time in the first embodiment.

FIG. 4 is a diagram showing a second field image of an image updated this time in the first embodiment.

FIG. 5 is a flowchart illustrating the operation of the second embodiment.

FIG. 6 is a block diagram showing a configuration of a conventional distance measuring device.

[Explanation of symbols]

 1, 2 lens 3, 4 image sensor 9, 10 memory 11 microcomputer 20, 21 video camera

Claims (2)

(57) [Claims] 1. A video camera which is provided in a pair of left and right or upper and lower sides and forms one image using an image signal of a first field and an image signal of a second field, respectively, and image signals output from these video cameras A distance measuring device that performs distance measurement based on the principle of triangulation using a video camera, wherein the triangulation is performed using only the image signal of the first field or only the image signal of the second field of the pair of video cameras. A distance measuring apparatus characterized in that the distance is measured based on the principle of the above. 2. A video camera which is provided in a pair of left and right or top and bottom and which forms one image using an image signal of a first field and an image signal of a second field, respectively, and image signals output from these video cameras. A distance measuring device that performs distance measurement based on the principle of triangulation using a video camera, wherein only the image signal of the first field of the pair of video cameras or only the image signal of the second field is used alternately. A distance measuring device characterized in that the distance is measured based on the principle of triangulation.