JPH05312568A - Apparatus for measuring inter-vehicle distance - Google Patents

Abstract

PURPOSE:To obtain an apparatus for measuring an inter-vehicle distance which enables stereoscopic-vision tracking of a target on the basis of distance information on the target. CONSTITUTION:Two image sensors 3 and 4 sensing an image in front or in the rear of a vehicle are disposed separately from each other and the image sensed by one image sensor is displayed on a display screen 11, while a window 21 is set in a prescribed area on the display screen 11. The distance to the preceding vehicle 5 displayed by this window 21 is detected by a microcomputer 10. Gates 23 to 26 for catch are provided around or inside the window 21, the distance to the preceding vehicle 5 acquired thereby is measured by the microcomputer 10 and information on this measured distance is subjected to comparison, whereby stereoscopic-vision tracking of the preceding vehicle 5 is executed. The stereoscopic-vision tracking can be executed on the basis of the distance information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle distance detecting device for optically measuring a distance between a vehicle and a vehicle traveling in front of or behind the vehicle using an image sensor.

[0002]

2. Description of the Related Art FIG. 14 is a block diagram of an optical distance detecting device using a conventional image sensor disclosed in Japanese Patent Publication No. 63-38085 and Japanese Patent Publication No. 63-46363. In FIG. 14, reference numerals 1 and 2 denote left and right lenses that are spaced apart by a base line length L, 3 and 4 denote image sensors disposed at the focal length f of the lenses 1 and 2, and 51 denotes image sensors 3 and 4. It is a signal processing device that calculates the distance to the target object 52 using an image signal sent from.

Next, the principle of the device for detecting the distance to the object 52 will be described. In the signal processing device 51, the image signals of the object 52 formed on the image sensors 3 and 4 through the lenses 1 and 2, respectively, are sequentially shifted and electrically overlapped, and the two image signals are the best match. Based on the principle of triangulation from the shift amount a at that time, the distance R to the object 52 is calculated by the following equation (1). R = f × L / a (1)

On the other hand, a method of tracking an image of a preceding vehicle imaged by an image sensor or the like is disclosed in JP-B-60-33352.
It is disclosed in the publication. According to this publication, an operator sets a tracking gate (window) surrounding a target to be tracked on the display screen while looking at the display screen.
It is configured by tracking the above target.

[0005]

Since the conventional distance detecting device compares the images picked up by a pair of left and right optical systems to obtain the distance to the object, these are used as the subject vehicle. When installing and trying to measure the inter-vehicle distance with the preceding vehicle while traveling, if another vehicle is traveling on the left side or the right side of the preceding vehicle, which vehicle is the inter-vehicle distance being measured? There was a problem that the person did not understand.

Further, when an image pickup device is mounted on a vehicle that is actually traveling and image tracking of a vehicle image in a window is performed by conventional matching between time-series scenes, a reference image and a comparison image are compared. Accumulation of the error at the time causes the window to deviate from the target vehicle image and stable image tracking cannot be performed, and in particular, there is a problem that the window shifts in the vertical direction when the vehicle bounces due to unevenness of the traveling road surface. ..

The present invention has been made in order to solve the above problems, and once a target is set, even if the target is moving, as long as it is within the field of view, it is possible to continuously reach the target. The objective is to obtain an inter-vehicle distance detection device that can measure the distance of the vehicle and that can detect which preceding vehicle is the target of which the inter-vehicle distance is being measured, even when multiple preceding vehicles are traveling. Image tracking is possible,
It is an object of the present invention to provide an inter-vehicle distance detecting device in which the size of a window changes depending on the detected inter-vehicle distance and an accurate inter-vehicle distance can be continuously detected.

[0008]

An inter-vehicle distance detecting device according to the present invention is capable of picking up a wide field of view including a preceding vehicle, and two image sensors arranged substantially vertically or horizontally apart from each other. Display means for displaying an image picked up by one of the upper and lower or left and right image sensors, window setting means for setting a window at a predetermined position on the screen of the display means, and the window setting means. A first distance detecting means for detecting a distance to the vehicle captured by the window and a second distance detecting means for each gate detecting a distance to the object captured by a plurality of gates provided around and inside the window. Of the distance detecting means and the plurality of distance information obtained from the first distance detecting means and the second distance detecting means, and the tracking win- dow is compared. It is provided with a microcomputer having a stereoscopic tracking means for tracking the vehicle image by c.

Further, the microcomputer changes the size of the window surrounding the vehicle image according to the detected distance to the vehicle, the image tracking means for tracking the image of the vehicle image by matching between scenes, and the window capture. And an output means for outputting the detected distance to the vehicle.

[0010]

The vehicle image captured by either one of the two image sensors according to the present invention is displayed on the display means, and the window is set at a predetermined position on the screen of the display means by the window setting means. By setting the image signal in this window as a reference signal by the first distance detecting means, the corresponding upper and lower or left and right images picked up by the image sensor are compared, and the deviation between both images is electrically detected to form a triangle. The distance to the object captured by the window is detected based on the principle of surveying, and the second
The distance detection means detects the distance to the object captured by the plurality of capture gates provided around and inside the window in the same manner as the first distance detection means,
The stereoscopic tracking of the vehicle image is performed by comparing the distance information obtained by the first and second distance detecting means by the stereoscopic tracking means.

Further, since the size of the window surrounding the vehicle image changes according to the detection distance and the image tracking means for matching between scenes is provided, the distance between vehicles to the target vehicle can be maintained while stable image tracking is performed. It is detected continuously.

[0012]

【Example】

Example 1. An example of detecting the inter-vehicle distance to the vehicle ahead of the host vehicle will be described below. FIG. 1 is a configuration diagram showing the configuration of the embodiment in this case. In FIG. 1, reference numerals 1 and 2 denote lenses constituting the upper and lower optical systems, which are separated by a base line length L, 3 and 4 are two-dimensional image sensors arranged corresponding to the lenses 1 and 2, and 5 is a follower. Indicates the preceding vehicle to be used. The distance detection device is configured as described above.

Reference numerals 6 and 7 are analog / digital converters for converting the analog signals input from the image sensors 3 and 4 into digital signals, and 8 and 9 are memories connected to the analog / digital converters 6 and 7. Reference numeral 10 is a microcomputer, and memories 8 and 9 are a display screen 11 and a window setting device 1 as display means described later.
Connected to 2.

The microcomputer 10 uses the image signal in the window set by the window setting device 12 as a reference signal to compare the image signals corresponding to the upper and lower sides or the left and right sides, detects the deviation, and is surrounded by the vehicle and the window. It has a first distance detecting means for calculating the distance to the target object.

Further, in the microcomputer 10,
A plurality of gates are set around and inside the window set by the window setting device 12, and the image signal of the area surrounded by the gate is set as a reference signal for each gate, and the corresponding image signal of the upper, lower, left or right is set. A second distance detecting means for comparing and detecting the deviation and calculating the distance to the subject surrounded by the vehicle and each gate is included, and also a stereoscopic tracking means is included. .. The stereoscopic tracking means compares a plurality of pieces of distance information obtained from the first distance detecting means and the second distance detecting means, and tracks a vehicle image using a tracking window.

Further, the microcomputer 10 changes the size of the window surrounding the vehicle image according to the detected distance to the vehicle, means for tracking the image of the target object in the window by matching the scenes, and the window. And means for outputting the distance information to the object surrounded by.

The display screen 11 is a display screen for displaying an image picked up by the upper image sensor 4 and is controlled by the microcomputer 10. The window setting device 12 is also connected to the display screen 11 to set a window for designating an object of distance measurement on an image, and an image tracking instruction switch 13 operated by a driver is connected. ..

Next, the operation will be described. For example, if the preceding vehicle image 5a to follow the image of the upper image sensor 4 enters as shown in FIG. 2 and the window 21 is set and displayed on the display screen 11, the driver drives the own vehicle. Then, the relative position between the preceding vehicle 5 and the host vehicle is changed, and the preceding vehicle image 5a is moved to a position within the window 21. Then, as shown in FIG. 3, when the image tracking instruction switch 13 is operated by the driver when the preceding vehicle image 5a enters the window 21, the distance to the preceding vehicle captured by the window 21 is first displayed. Is measured, and the method will be described below.

First, the microcomputer 10 reads the pixel signal in the window 21 from the memory 9 and uses it as a reference image signal for distance calculation. Then, in the memory 8 in which the image signal of the lower image sensor 3 is stored, an area corresponding to the window 21 is set in the microcomputer 1.
0 is selected, and the image signal of the memory 8 is sequentially shifted pixel by pixel with respect to the reference image signal, and the sum of absolute values of signal differences between upper and lower pixels is calculated. That is,
The position of the image that most matches the image in the window 21 is obtained by sequentially shifting it by one pixel.

At this time, the area in the memory 8 involved in the calculation is the area 22 corresponding to the position of the window 21, as shown in FIG. As described above, the upper and lower pixels are compared, the pixel shift amount when the sum of the absolute values of the difference signals becomes the minimum is n pixels, the pixel pitch is p, the baseline length of the optical system is L, and the lens is When the focal lengths of 1 and 2 are f, the distance R to the preceding vehicle 5 is obtained by the following equation (2), and the distance to the object in the window can be measured as described above. R = f × L / n × p (2)

Next, as shown in FIG. 5, a plurality of trapping gates 23, 24, 25, and 26 provided around the window 21 for trapping the preceding vehicle image 5a, respectively, are trapped. The distance to is similarly measured by the method shown in the above formula (2). Here, the trapping gates 23, 2
The distance to the object captured by 4, 25, 26 must be detected by comparing the images in the calculation areas 27, 28, 29 corresponding to the capturing gates 23, 24, 25, 26, respectively. You can

As described above, the distance to the object caught by the window and the plurality of gates is detected every moment, and the distance information is compared by the microcomputer 10. In the case of FIG. 5, the window captures the image of the preceding vehicle 5a, detects the distance R to the preceding vehicle 5, and the capturing gates 23, 24, 25, and 26 detect the distance to the background of the preceding vehicle 5, Further, the capturing gate 24 detects the distance to the road in front of the preceding vehicle 5, and the distance information is balanced as a whole.

Next, as shown in FIG. 6, when the preceding vehicle image 5a moves to the upper right on the image and the window 21 shifts,
The roof portion of the preceding vehicle image 5a enters the capturing gate 23, and the right end portion of the preceding vehicle image 5a enters the capturing gate 26. At this time, the distances detected by the window 21 and the trapping gates 23, 24, 25, and 26 are R, A, B, C, and D, respectively, and comparing these, the distance A is almost the same as the distance R. Therefore, the distance B is the distance to the road ahead of the preceding vehicle 5, which is smaller than the distance R.
The microcomputer 10 commands the window setting device 12 to move the window 21 to the right. In this way, the window setting device 12 which receives the command from the microcomputer 10 moves the window so as to surround the preceding vehicle image again, as shown in FIG.

As described above, the distance information obtained from the window 21 at any time and a plurality of capturing gates 23, 24, 2
If the distance information obtained from 5 and 26 is compared and the preceding vehicle 5 is captured by these distance information so that the distance can be balanced as a whole, window tracking by stereoscopic view on the image becomes possible.

By the way, when the tracking target moves on the image at a relatively slow speed, the target vehicle can be tracked by the stereoscopic tracking, but in actual traveling, the vehicle bounces due to the unevenness of the road surface. By the target vehicle image 5a
May move on the image at a relatively high speed, and a sufficient effect cannot be obtained only by stereoscopic tracking. Therefore, before performing stereoscopic tracking, image tracking of the preceding vehicle image 5a is performed by conventional scene matching. This image tracking is somewhat rough. Also, this image tracking is Shokoku Sho 60
The apparatus is similar to the conventional apparatus disclosed in Japanese Patent Publication No. 33352 or Japanese Patent Publication No. 1-35305, and detailed description thereof will be omitted.

When the distance between the preceding vehicle 5 and the host vehicle changes and the size of the preceding vehicle image 5a changes in the image, the window 21 and the capturing gates 23 and 24 are changed according to the distance obtained from the window 21. , 25, 26 are also changed. For example, if the inter-vehicle distance 7a with respect to the preceding vehicle image 5a becomes longer than that in the case of FIG. 7, the preceding vehicle image 5a becomes a little smaller as shown in FIG. 8. Therefore, as shown in FIG. Also, the trapping gates 23, 24, 25 and 26 are also made smaller accordingly.

On the contrary, when the inter-vehicle distance becomes short, the preceding vehicle image 5a becomes slightly large as shown in FIG. 10, so that the window 21 and the trapping gates 23, 24, 25 are made as shown in FIG. , 26 is increased. As described above, by setting a window having an appropriate size for the preceding vehicle image 5a, the influence of the background image is small, the S / N ratio in the window is small, and accurate distance measurement is possible. ..

As described above, no matter how the preceding vehicle image 5a moves on the display screen 11, the window 21 tracks the preceding vehicle image 5a, and the inter-vehicle distance between the preceding vehicle 5 and the own vehicle is accurately measured. It detects continuously. In addition, the information on the detected distance is output to a display device and an alarm device (neither is shown).

In the above embodiment, the trapping gate is set around the window as shown in FIG. 5, but it is also possible to set the trapping gate inside the window as shown in FIGS. ..

[0030]

As described above, according to the present invention, the window is set at a predetermined position of the image sensor for picking up the front or rear of the vehicle and the display screen for displaying the image picked up by the image sensor. , Detect the distance to the target captured by this window, and provide a plurality of capture gates around or inside the window, and detect the distance to the target surrounded by these capture gates. Since the distance information is compared, the stereoscopic tracking of the vehicle image based on the distance information can be performed. Further, since the target vehicle image is surrounded by the window and displayed on the display screen, the driver can know the vehicle whose inter-vehicle distance is detected.

Furthermore, stable image tracking is possible by combining with conventional image tracking by matching in the scene, and the window size is changed according to the detected inter-vehicle distance. The distance can be detected continuously.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inter-vehicle distance detecting device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state in which a preceding vehicle image is displayed on a display screen in which a window is set according to the embodiment.

FIG. 3 is an explanatory diagram showing a state in which a preceding vehicle image is included in a window according to the embodiment.

FIG. 4 is an explanatory diagram showing an image area compared with a reference image in a window according to the embodiment.

FIG. 5 is an explanatory diagram showing a capture gate provided around a window and an image area to be compared with a reference image according to the embodiment.

FIG. 6 is an explanatory view showing a state where the window is displaced from the image of the preceding vehicle according to the embodiment.

FIG. 7 is an explanatory diagram showing a state in which a window tracks an image of a preceding vehicle according to the embodiment.

FIG. 8 is an explanatory diagram showing a state in which an inter-vehicle distance becomes long and a preceding vehicle image becomes small according to the embodiment.

FIG. 9 is an explanatory view showing a state in which the window is made smaller according to the inter-vehicle distance according to the embodiment.

FIG. 10 is an explanatory diagram showing a state in which the inter-vehicle distance is shortened according to the embodiment.

FIG. 11 is an explanatory diagram showing a state in which a window is enlarged according to an inter-vehicle distance according to the above embodiment.

FIG. 12 is an explanatory view showing another example of the trapping gate applied to the inter-vehicle distance detecting device of the present invention.

FIG. 13 is an explanatory diagram showing still another example of the capturing gate applied to the inter-vehicle distance detecting device of the present invention.

FIG. 14 is a configuration diagram of a conventional distance detection device.

[Explanation of symbols]

 1 lens 2 lens 3 image sensor 4 image sensor 5 preceding vehicle 5a preceding vehicle image 6 analog / digital converter 7 analog / digital converter 8 memory 9 memory 10 microcomputer 11 display screen 12 window setting device 13 image tracking instruction switch 21 window 22 window comparison region 23 trapping gate 24 trapping gate 25 trapping gate 26 trapping gate 27 trapping gate comparison region 28 trapping gate comparison region 29 trapping gate comparison region

Claims (2)

[Claims] 1. Comparing image signals formed on an image sensor by a pair of upper and lower or left and right optical systems, and electrically detecting a deviation between the two image signals to detect the front or rear of the host vehicle based on the principle of triangulation. A distance detecting device for measuring a distance to a traveling vehicle, a display means for displaying an image picked up by one of the upper and lower or left and right image sensors, and a vehicle to be noted on the image displayed on the display means. A window setting means for setting a window surrounding the window is compared with corresponding image signals in the upper, lower, left and right directions using the image signal in the window set by the window setting means as a reference signal, and the deviation is detected to detect the vehicle and the window. A plurality of gates are set around and inside the first distance detecting means and the window for calculating the distance to the object surrounded by, and each gate is set. For each gate, the image signal of the area surrounded by the gate is used as a reference signal and compared with the corresponding image signal above and below or left and right to detect the deviation and the distance between the vehicle and the object surrounded by each gate. A vehicle distance including a second distance detecting means for calculating a distance and a microcomputer for performing stereoscopic image tracking of the vehicle image by comparing respective distance information obtained by the plurality of distance detecting means. Detection device. 2. The microcomputer comprises means for changing the size of a window surrounding the vehicle image according to a detection distance to the vehicle, and means for tracking an image of a target object in the window by matching between scenes. 2. The vehicle distance detection device according to claim 1, further comprising: a unit that outputs distance information to an object surrounded by the window.