JPH09113265A - Distance measuring device - Google Patents

Abstract

(57) Abstract: A distance measuring device having a small amount of data, a simple processing method, and less fear of malfunction. SOLUTION: A phase difference is obtained from an image signal obtained in a detection region W1 or a detection region W2 selected from a visual field region V of a pair of sensors arranged corresponding to a plurality of distance measurement points Pmn set in a grid pattern. Calculate and obtain the distance distribution consisting of the measured distances of the distance measuring points Pmn, and use the distance distribution
This is a distance measuring device that repeatedly obtains the distance D up to 20 at regular intervals. The detection area W1 or the detection area W2 is set in the vehicle 20.
Select according to the previous value of the distance D to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring a distance, particularly an object located in front of a vehicle such as a vehicle.

[0002]

2. Description of the Related Art Development of a technique for improving safety when a vehicle is traveling is in progress. For example, in order to avoid a rear-end collision accident, the distance between the object and the object that may be a hindrance to the traveling is obstructed. When the vehicle is measured closer than a predetermined distance and the driver is warned or the vehicle speed is automatically reduced (eg, Japanese Patent Publication No. 3-44005).
(See Japanese Patent Publication).

As a device for measuring the distance mounted on such a device, a pair of left and right cameras using an image sensor such as a charge coupled device (CCD) is provided in front of the vehicle, and the images on the images of the respective cameras are displayed. There is known a technique for obtaining a distance by a so-called stereo method based on the principle of triangulation for calculating the displacement of the position of an object (for example, see Japanese Patent Laid-Open No. 7-43149).

[0004]

However, for example, as shown in FIG. 5, if there is a center line 1 in the visual field V of the sensor, it is easy to make a malfunction by judging this center line 1 as an object and issuing an alarm. There's a problem. When seven distance measuring points P are set in the visual field area V in the vertical direction and seven horizontal measuring points in the horizontal direction, the image data of all the distance measuring points P (49 in total) in the visual field area V is processed, so that the data amount is large. There are many problems that the processing method becomes complicated,
There is also a problem that an expensive device with high performance is required for an arithmetic unit for processing this.

In order to solve the above problems, the applicant of the present invention calculates the phase difference from the image signals obtained by a pair of sensors arranged corresponding to a plurality of distance measuring points set in a grid pattern. A distance distribution including the measured distances of the distance measuring points is calculated, a correlation of the distance measuring points is obtained from the distance distribution, and at least three distance measuring points are defined using the correlation. A determination value of a detection area including a dimensional area is calculated, and when the determination value is smaller than a set value, it is determined that an object exists in the detection area, and the distance measuring point that defines the detection area is determined. We proposed a distance measuring device that calculates the distance to the object using the distance distribution (Japanese Patent Application No. 7-155272).

[0006] It is an object of the present invention to provide a distance measuring device having a new structure different from the invention of the above-mentioned application, which has a small amount of data and a simple processing method and is less likely to malfunction. To do.

[0007]

In order to solve the above-mentioned problems, the present invention provides a detection area selected from a field-of-view area of a pair of sensors arranged corresponding to a plurality of distance measuring points set in a grid pattern. The phase difference is calculated from the image signal obtained in step 1 to obtain a distance distribution consisting of the measured distances of the distance measuring points, the distance to the object is repeatedly obtained using the distance distribution at regular intervals, and the detection area is set to the object. It is selected according to the previous value of the distance to.

Further, according to the present invention, a phase difference is calculated from an image signal obtained in a detection area selected from the visual field areas of a pair of sensors arranged corresponding to a plurality of distance measuring points set in a grid pattern. Then, the distance distribution consisting of the measured distances of the distance measuring points is obtained, and the distance to the object is repeatedly obtained using the distance distribution at regular time intervals, and when the previous value of the distance to the object is larger than a predetermined value, The upper detection area is selected, and when the previous value of the distance to the object is smaller than the predetermined value, the lower detection area is selected.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Since the detection area is selected according to the previous value of the distance to the object, the amount of data is small because the image signal data of only the detection area in the visual field area of the sensor is used. , Data processing becomes relatively easy. In addition, the probability that an object other than the object to be detected will deviate from the detection area is increased, and the measurement accuracy can be improved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments described in the accompanying drawings on the assumption that the distance to an object located in front of the vehicle is measured.

FIG. 1 is a block diagram showing the configuration of the embodiment, and 10 is a vehicle (object) 20 located in front of the own vehicle corresponding to a plurality of distance measuring points P set in a grid pattern described later.
Is a distance measuring unit (camera) for obtaining an image signal including
As sensors, image sensors 12L and 12R, which are CCDs having a vertical direction coinciding with the baseline direction of a pair of left and right lenses 11L and 11R, are arranged, and analog output signals of the image sensors 12L and 12R are amplified by amplifiers 13L and 13R, A
The D (analog-digital) converters 14L and 14R are converted into digital conversion signals by sampling in a predetermined cycle and stored in the memories 15L and 15R, respectively. The image signals stored in the memories 15L and 15R are provided in the subsequent stage of the distance measuring unit 10. The calculation is performed to calculate the distance D to the vehicle 20 by being output to the microcomputer 30 connected to the computer 30. The processing method of the microcomputer 30 will be described later.

FIG. 2 is an explanatory diagram when the upper detection area is selected. The distance measuring points P are seven in the vertical and horizontal directions of the visual field area V, for a total of 49 distance measuring points P11 to
P77 is set in a grid pattern and these distance measuring points P11
P77 are arranged at equal intervals in the vertical and horizontal directions. W1 is an upper detection area, and distance measuring points P41 to P77 are set in the upper detection area W1. The distance measuring points P41 to P77 in the upper detection area W1 are scanned by the drive pulse signal and sequentially read out for each one distance measuring point Pmn.
47 are read one by one from left to right in the horizontal direction, and 5
Like the distance measuring points P51 to P57 on the line and the distance measuring points P61 to P67 on the sixth line, the distance measuring points P71 to P71 on the final seventh line.
Scan to P77. The image signals of the distance measuring points P41 to P77 in the upper detection area thus obtained are output to the microcomputer 30.

FIG. 3 is an explanatory view when the lower detection area is selected. W2 is a lower detection area, and distance measuring points P11 to P47 are set in the lower detection area W2. Distance measuring point P11 in the lower detection area W2
P47 is sequentially scanned from the distance measuring points P11 to P17 on the first line to the distance measuring points P41 to P47 on the fourth line. The image signals of the distance measuring points P11 to P47 in the lower detection area W2 are
It is output to the microcomputer 30.

The microcomputer 30 of this embodiment performs the following processing. First, in order to obtain the distance distribution of the distance measurement points Pmn, one of the left and right images is fixed and the other is sequentially shifted, and the left and right images are compared according to the shift amount, and the shift is performed when the left and right images are most in agreement. Amount, that is, the phase difference is calculated from the image signal and the measurement distance D of each distance measurement point Pmn is calculated.
Perform the operation to find mn.

Next, the distance measuring point Pmn is calculated from the distance distribution.
The correlation is obtained by, for example, obtaining the absolute value of the difference in the measured distance Dmn between the distance measurement points Pmn.

Next, the correlation value is used to calculate the determination value S of the detection area A, which is a two-dimensional area defined by four distance measurement points Pmn, and the distance measurement point Pmn that defines the detection area A is calculated, for example. The determination value S is obtained by processing with a predetermined arithmetic expression using the above correlation. FIG. 4 is an enlarged view of an unspecified part of the upper detection area W1 shown in FIG. 2 or the lower detection area W2 shown in FIG. Distance measuring point P
A detection area A is a two-dimensional area having a quadrangular projected shape defined by aa, Pab, Pba, and Pbb (a and b are 1 to 7), and distance measuring points Paa, Pab, Pba, and Pbb located at the respective vertices. The following calculation for obtaining the absolute value of the difference between the measured distances Daa, Dab, Dba, Dbb, adding each of the absolute values corresponding to the opposite sides of the quadrangle, and then multiplying the addition results of the two sets By performing processing based on the equation, the determination value S for all the detection areas A is obtained.

S = (| Daa−Dab | + | Dba−Dbb |)
× (| Daa-Dba | + | Dab-Dbb |) where Dmn is the measurement distance of the distance measurement point Pmn

Next, when the judgment value S is smaller than a preset setting value (for example, "10") which is a threshold value for judgment, it is judged that the vehicle 20 is present in the detected area A. .

Then, the distance D to the vehicle 20 is obtained using the distance distribution of the distance measuring points Paa, Pab, Pba, Pbb that define the detected area A. For example, the distance measuring points Paa, which constitute the detected area A, The distance D to the vehicle 20 is obtained by selecting the minimum value from the measured distances Daa, Dab, Dba, Dbb of Pab, Pba, Pbb.

The microcomputer 30 repeatedly calculates the distance D to the vehicle 20 at regular intervals (for example, 0.4 seconds), and when the distance D is larger than a predetermined value (for example, 15 m), the upper detection area W1 is selected. If the distance D is smaller than the predetermined value, the lower detection area W2 is selected. That is, the detection area W
1 and W2 are selected according to the previous value of the obtained distance D, and the distance D to the vehicle 20 is obtained by the processing described above while switching the upper detection area W1 or the lower detection area W2.

The distance D to the vehicle 20 thus obtained is
It can be sent to the ECU (engine control unit) or meter side of the vehicle and used as information to give attention to the driver and control such as automatically lowering the traveling speed as in the conventional technology. it can.

By the way, as shown in FIG. 2, when the vehicle 20 is located at a long distance, if the upper detection area W1 is selected and only the distance measurement points P41 to P77 of the upper detection area W1 are used, The probability that an object other than the object to be detected, such as the center line 1, deviates from the upper detection area W1, increases, and it is possible to reduce the risk of a malfunction that recognizes the center line 1 as an object and issues a false alarm.

Further, as shown in FIG. 3, when the vehicle 20 is located at a short distance, the lower detection area W2 is selected, and the image signals of only the distance measuring points P11 to P47 of the lower detection area W2 are selected. If used, the probability that the vehicle 21 ahead of itself (the vehicle preceding the vehicle 20) will deviate from the lower detection region W2 is increased, and the measurement accuracy can be improved.

Further, according to this embodiment, the distance measuring points in the upper detection area W1 or the lower detection area W2 (total of 28
Since only the individual image signals are used, the amount of data processed by the microcomputer 30 can be small, and the data processing becomes relatively easy.

In the present embodiment, the upper detection area W1 or the lower detection area W2 is selected according to the previous value of the distance D to the vehicle 20, but from among three or more detection areas. An appropriate detection area may be selected according to the previous value of the distance D.

In this embodiment, the distance measuring point Pmn is set to 4
Although the process of calculating the determination value S from the detection areas A defined by individual pieces is performed, this process is not performed, and the distance D to the object from the minimum value of the distance distribution of the measurement distance Dmn at each distance measurement point Pmn is calculated. You may ask.

Further, in this embodiment, the distance measuring unit 10 sends the image signals of the distance measuring points P41 to P77 in the upper detection area W1 or the distance measuring points P11 to P47 in the lower detection area W2 to the microcomputer 30. The distance measuring unit 10 outputs the image signals of the distance measuring points P11 to P77 of the visual field area V to the microcomputer 30, and outputs the distance measuring points P41 to P77 of the upper detection area W1 or the lower distance measuring points P41 to P77. Only the image signal data of the distance measuring points P11 to P47 in the detection area W2 may be processed by the microcomputer 30, and the same effect as this embodiment can be obtained.

[0028]

According to the present invention, a phase difference is calculated from an image signal obtained in a detection area selected from the visual field areas of a pair of image sensors arranged corresponding to a plurality of distance measuring points set in a grid pattern. Then, a distance distribution consisting of the measured distances of the distance measuring points is obtained, the distance to the object is repeatedly obtained at regular intervals using the distance distribution, and the detection area is selected according to the previous value of the distance to the object. Is what
By selecting the detection area according to the previous value of the distance to the object, the amount of data is small because the image signal data of only the detection area in the field of view of the sensor is used. In addition, the probability that an object other than the object to be detected deviates from the detection area becomes high, and the measurement accuracy can be improved.

Further, according to the present invention, the phase difference is calculated from the image signal obtained in the detection area selected from the visual field areas of the pair of image sensors arranged corresponding to the plurality of distance measuring points set in a grid pattern. Then, the distance distribution consisting of the measured distances of the distance measuring points is obtained, the distance to the object is repeatedly obtained at regular intervals using the distance distribution, and the previous value of the distance to the object is larger than a predetermined value. Selects the upper detection area, and selects the lower detection area when the previous value of the distance to the object is smaller than the predetermined value. By selecting according to the previous value, since the image signal data of only the detection area is used in the visual field area of the sensor, the data amount can be small, the data processing becomes relatively easy, and
The probability that an object other than the object to be detected deviates from the detection area is increased, and the measurement accuracy can be improved.

[Brief description of the drawings]

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

FIG. 2 is a view for explaining a case where an upper detection area is selected in the same embodiment.

FIG. 3 is a diagram illustrating a case where a lower detection region of the above-described embodiment is selected.

FIG. 4 is an enlarged view in which an unspecified part of the detection area of the above-described embodiment is extracted.

FIG. 5 is a diagram illustrating a conventional example.

[Explanation of symbols]

 10 Distance measuring unit 12R, 12L Image sensor (sensor) 20 Vehicle (object) 30 Microcomputer P Distance measuring point V Field of view area W1 Upper detection area (detection area) W2 Lower detection area (detection area) D Distance

Claims (2)

[Claims] 1. The distance measurement is performed by calculating a phase difference from an image signal obtained in a detection area selected from the visual field areas of a pair of sensors arranged corresponding to a plurality of distance measurement points set in a grid pattern. Obtaining a distance distribution consisting of measured distances of points, repeatedly obtaining a distance to an object using the distance distribution, and selecting the detection region according to the previous value of the distance to the object. Distance measuring device. 2. The distance measurement is performed by calculating a phase difference from an image signal obtained in a detection area selected from the visual field areas of a pair of sensors arranged corresponding to a plurality of distance measurement points set in a grid pattern. Obtain the distance distribution consisting of the measured distances of points, repeatedly obtain the distance to the object using the distance distribution at regular time intervals, and if the previous value of the distance to the object is greater than a predetermined value, detect the upper side. A distance measuring device, wherein an area is selected, and when the previous value of the distance to the object is smaller than the predetermined value, the lower detection area is selected.