JPH07266920A - Curved road alarm device - Google Patents

Abstract

PURPOSE:To realize a curved road alarm device to give an alarm to danerous car speed by finding a radius of curvature of a curved road without finding the radius of curvature of the curved road from a white line coordinate in a two-dimensional picture image and without setting a transmitter on the curved road. CONSTITUTION:A radius of curvature of a curved road is detected by collating a letter pattern decided by way of applying binarization treatment and edge treatment to a picture image signal obtained from a two-dimensional camera 1 to pick up an image of a curve curvature display sign set on a curved road and a letter pattern of a previously memorized curve curvature, standard allowed car speed previously memorized is found from this radius of curvature, and when current car speed 2 is higher than allowed car speed multiplying the standard allowed car speed with a correction coefficient corresponding to a previously memorized vehicle surrounding circumstance, it is judged as over speed and an alarm is energized for a specified period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved road warning device, and more particularly to a device for issuing a warning when the vehicle speed is dangerous when a vehicle enters a curved road.

[0002]

2. Description of the Related Art In such a curved road warning device, it is necessary to first determine the radius of curvature of the curved road.
As such a conventional example, JP-A-3-186713 and
No. 3-139706 and the like, two white lines (guide lines) are detected from the output image of the two-dimensional camera, and the radius of curvature of the curved road is obtained from the coordinates of the white lines.

However, when the radius of curvature of the curved road is calculated from the white line coordinates in the two-dimensional image as in the conventional example, there are the following problems.

(1) At night, when the white line is not sufficiently illuminated, or when a soundproof wall is installed along the road, the white line in the distance cannot be detected and an accurate radius of curvature of the curved road is required. Absent.

(2) Since it is based on the "principle of monocular triangulation", the direction of the camera optical axis must be set strictly with respect to the road surface in calculating the distance of the white line, and when the vehicle pitches. Calculation error occurs in the radius of curvature of the curved road.

(3) In a curved road having a gradient or a bank, it is based on the above-mentioned principle of monocular triangulation.
There is a difference in the calculation of the radius of curvature of the curved road.

As described above, Japanese Patent Laid-Open No. 54-559 discloses a curved road warning device having no drawbacks based on the principle of monocular triangulation.
No. 23 publication is cited.

In this device, a transmitter is provided near the entrance of the curved road, the reference permissible vehicle speed information is transmitted from the transmitter to the receiver of the vehicle entering the curved road, and the received reference permissible vehicle speed is received. Based on the above, an alarm is issued based on the relationship with the current vehicle speed.

[0009]

However, in the case of such a conventional technique, it is necessary to newly install a transmitting device on each curved road, and it takes a long period to completely install the transmitting device and the transmitter is completely installed. Until it is done, it is not possible to exert sufficient effect.

In addition, there is a problem in that when such a transmitting device is newly installed on each curved road, a considerable cost is required and the maintenance thereof is also a heavy burden on the road installation / manager side.

Therefore, according to the present invention, the radius of curvature of the curved road is not calculated from the white line coordinates in the two-dimensional image, and the radius of curvature of the curved road is calculated without installing a transmitter on the curved road, and the dangerous vehicle speed is obtained. The object is to realize a curved road warning device that gives a warning to the driver.

[0012]

In order to achieve the above object, a curved road warning device according to the present invention is mounted on a vehicle, and is a two-dimensional camera for photographing a curve curvature radius display sign of a road, and a vehicle speed detection means. A vehicle surrounding environment detecting means, an alarm device, a character pattern determined by performing binarization processing and edge processing on the image signal obtained from the camera, and a character pattern having a previously stored curve curvature radius. The radius of curvature of the curved road is detected by matching, and the reference allowable vehicle speed is obtained from a value obtained by multiplying the curvature radius of the curve by a correction coefficient corresponding to the vehicle surrounding environment stored in advance. Signal processing means for activating the alarm device for a certain period of time when it is large.

The means for detecting the surrounding environment of the vehicle is at least one of a wiper switch, a lamp switch, a load sensor, and an outside air temperature sensor.

Further, the signal processing means stores a memory storing a character pattern of a radius of curvature of the curve, a reference allowable vehicle speed corresponding to the radius of the curve curvature, and a surrounding environment of the vehicle for correcting the reference allowable vehicle speed. And a memory storing the correction coefficient.

[0015]

[Function] A sign indicating the radius of curvature is installed at the entrance of the curved road of most highways, and the curvature radius is displayed on most of the sharp curved roads where attention must be paid to the vehicle speed when entering the curved road. The display value is also a value set in advance at the time of design and can be judged as a sufficiently accurate value.

Therefore, in the present invention, the signal processing means performs the binarization processing and the edge processing on the image signal obtained from the two-dimensional camera mounted on the vehicle to detect the character pattern.

Then, by comparing and collating this character pattern with the character pattern of the curve curvature radius stored in the memory in advance, the curve curvature radius included in the curvature radius indication mark of the curved road is recognized, and this curve curvature is recognized. The reference allowable vehicle speed stored in advance in the memory is obtained from the radius.

However, the above-mentioned reference allowable vehicle speed is not always an appropriate value depending on the surrounding environment of the vehicle such as the road surface condition of the vehicle and the vehicle operating condition. That is, if the reference allowable vehicle speed is set assuming the worst situation, the smooth traffic flow is disturbed and the own vehicle and surrounding vehicles are exposed to a dangerous state, and the vehicle speed is set assuming a favorable condition. Then, depending on the situation, there is no point in restricting the entry into the curved road, and there is a drawback that the vehicle is exposed to a dangerous state.

Therefore, in the present invention, the signal processing means retrieves various correction coefficients stored in advance in the memory in accordance with the vehicle surrounding environment according to the vehicle surrounding environment detected by the vehicle surrounding environment detecting means, and extracts them. By multiplying the obtained reference permissible vehicle speed, the permissible vehicle speed corrected according to the surrounding environment of the vehicle is obtained.

Then, the signal processing means compares the corrected allowable vehicle speed with the current vehicle speed detected by the vehicle speed detecting means, and when the current vehicle speed is higher than the corrected allowable vehicle speed, the alarm device is activated for a certain period of time so that the signal processing means An alarm can be issued against.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a curved road warning device according to the present invention. In the drawing, 1 is a photograph of a curve curvature radius display sign attached to a vehicle and installed on a curved road of a highway. A two-dimensional camera for controlling the vehicle speed, a vehicle speed sensor as a vehicle speed detecting means, a vehicle surrounding environment detecting means 3 and a wiper switch 31, a lamp (lighting) switch 32, a vehicle body and a bed, which are attached to the weight of the bed. Including a load sensor 33 and an outside air temperature sensor 34, 4 is an alarm device, and 5 is a control unit as a signal processing means.

The control unit 5 also includes an A / D converter 51 for converting the output image of the two-dimensional camera 1 into a digital signal, and a frame for storing the digital signal from the A / D converter 51. The memory 52, the input circuit 53 for taking in the output signals from the switches 31 and 32 and the sensors 2 and 33 and 34, and the brightness in the image captured by binarizing the data stored in the frame memory 52. The CPU 54 for extracting the edge portion and this C
A frame memory 55 that stores data binarized by the PU 54, a memory 56 that stores character patterns (templates) in advance, a ROM 57 that stores programs and data to be executed by the CPU 54 in advance,
The alarm device 4 indicates the processing result calculated by the CPU 54.
And an output circuit 58 for outputting.

FIG. 2 shows a flow chart of a processing program executed by the CPU 54 shown in FIG.
The operation of the embodiment of the present invention shown in FIG. 1 will be described below with reference to this flowchart.

First, initialization processing is performed on the CPU 54 (step S1).

Next, the timer counter built in the CPU 54 is reset to "0" and the output circuit 58 is initialized to OFF (step S3).

Further, a vehicle speed signal is read from the vehicle speed sensor 2 via the input circuit 53, and the result is stored as the own vehicle speed V (step S4).

Further, an output signal indicating the operating condition of the wiper switch 31 is read via the input circuit 53 (step S5).

An output signal indicating the lamp lighting state is read from the lamp switch 32 via the input circuit 53 (step S5).

Further, an output signal indicating the loading condition of the vehicle is read from the load sensor 33 via the input circuit 53 (step S6).

Further, an output signal indicating the temperature of the outside air is read from the outside air temperature sensor 34 via the input circuit 53 (step S7).

Next, the coefficient for correcting the reference allowable vehicle speed on the curved road, which will be described later, is determined by the switch / sensor output read in steps S4 to S7 (step S8).

FIG. 3 shows an example of the correction coefficient.
(a) is a correction coefficient K ₁ (0
<K ₁ ≦ 1), and when the rain or the like becomes heavy, it is necessary to set the allowable vehicle speed on a curved road to a low value. Therefore, the wiper is “OFF” (K ₁ = 1) → “Intermittent operation” →
The correction coefficient K ₁ is made smaller in the order of “when LOW operation” → “when HIGH operation”.

FIG. 7B shows a correction coefficient K ₂ (0 <K ₂ ≦ 1) according to the operating state of the vehicle lamp, and it is necessary to set the allowable vehicle speed on the curved road to be lower at night than at daytime. Therefore, when the lamp is “OFF” (K ₂ = 1) → “When only the sidelight is ON” → “When the headlight is a low beam” →
The correction coefficient K ₂ is reduced in the order of “when the headlight is a high beam”.

FIG. 7C shows the condition of the vehicle load, that is, the load capacity.
Correction coefficient K according to₃(0 <K₃≦ 1), and
Correction coefficient K only when the load is appropriate₃= 1 and this
If it is on the empty side or the loading side of the range, lower the allowable vehicle speed.
Correction coefficient K ₃Is set.

FIG. 3D shows a correction coefficient K ₄ according to the outside temperature.
(0 <K ₄ ≦ 1) is indicated, K ₄ = 1 at 0 ° C or higher, and it is necessary to reduce the allowable vehicle speed on curved roads assuming freezing and snowfall below freezing. The shape correction coefficient K ₄ is used.

The correction coefficients K _{1 to} K ₄ as described above are used.
Is stored in the ROM 57 in advance, and steps S4 to S7 are performed.
The correction coefficients K _{1 to} K ₄ may be determined in accordance with

After the correction coefficients K _{1 to} K ₄ are obtained in this way, the digital signal of the two-dimensional camera 1 output from the A / D converter 51 is stored in the frame memory 52 (step S9).

The two-dimensional image data once stored in the frame memory 52 is read out, the binarization processing is performed as described above, the edge processing for extracting the luminance edge portion in the captured image is performed, and the processing result data is obtained. It is stored in the frame memory 55 (step S10).

Therefore, by this binarization processing and edge processing, the contours of the character portions such as objects and signs in the image captured by the camera 1 are extracted and stored in the frame memory 55 as character pattern data. Become.

Next, the CPU 54 uses the frame memory 55.
The character pattern data stored in the memory is compared with the character pattern preset in the memory 56.

[0041] As shown in Table 1 below as the registration pattern, the capital letters "R", the number "0" to "9", lowercase "m" is the template data _{t R, t 0 ~t 9,} t
Each template is registered and set as _m , and template matching processing is executed to determine whether or not the registered pattern exists in the frame memory 55 (step S
11).

[0042]

[Table 1]

Then, in step S11, "R ○○
When a pattern corresponding to "○ m" (○ is a number) is detected, the 4-digit "○○" part is recognized as a curve curvature radius value (m unit) (step S12).

Description of Template Matching Here, the process of recognizing the curve curvature radius value in step S12 will be described in detail below.

FIG. 4 shows a state in which the vehicle 10 is entering the clockwise curved road 20. At the entrance of the curved road 20, a curve curvature display sign 30 is erected as shown.

An example of an image taken by the two-dimensional camera 1 mounted on the vehicle 10 is shown in FIG.

Now, the image on the two-dimensional screen shown in FIG. 5 is a two-variable real function z = f (that represents the entire density value f (x, y) of the point coordinates (x, y) on the screen. It is represented by x, y).

When the density value g (x, y) of the processed image is obtained from the density value f (x, y) of the original image by a certain processing (for example, the above-described binarization processing), if the processing is linear processing, The formula holds.

[0049]

[Equation 1]

Here, α (x, y) is a parameter defined by the processing content and is called a weighting function.

That is, the above equation (1) is applied to the point (u, v) of the input image at the density value g (x, y) of the processed image at the point (x, y) on the screen imaged by the camera 1. ), The concentration value f (u, v) contributes with the weight α (x−u, y−v),
It indicates that this is determined by the difference (x−u, y−v) in the coordinate values between the point (x, y) and the point (u, v).

In the template matching, the similarity, the identity, and the difference between the standard image (template image) t (x, y) prepared in advance and the original image are evaluated and recognized using the following scales.・ Perform the process of making a distinction

Typical template manching is (1)
In the equation, the weighting function α (x, y) is set to the inverted value t (−x, −y) of the template (α (x, y) = t (−
x, -y)). This is expressed by the following equation using a normalization factor.

[0054]

[Equation 2]

By substituting g '(x, y) obtained by the equation (2) into g (x, y) of the equation (1), | g'
(x, y) | can be used as a measure of similarity evaluation between the template and the original image.

In the case of the above embodiment, the original image or the template is enlarged or reduced using the area within the outline of the character candidate as a parameter so that the size of the character pattern in the original image and the size of the template substantially match. Later, the above | g ′ (x, y) | is obtained, and if the value is equal to or larger than the set value, it can be recognized that the template character exists in the image. (If the template and the original image completely match, | g '(x, y) | = 1.)

In this way, it is determined in step S13 whether or not the curve curvature radius value is recognized. If it is determined that the curve curvature radius value is recognized, the recognition value is set to R (step S14).

Then, based on this recognized R value, RO
The reference allowable vehicle speed on the curved road, which is set in advance in M57 by an experiment or a calculation, is obtained from the mapping data shown in the figure, and this reference allowable vehicle speed is set to f (R) (step S1).
5). The allowable vehicle speed with respect to the radius of curvature of the curve is publicly known as disclosed in Japanese Patent Laid-Open No. 54-55923.

Since the reference allowable vehicle speed f (R) does not take into consideration the surrounding environment of the vehicle, the correction coefficients K _{1 to} K ₄ obtained in step S8 are multiplied by the allowable vehicle speed f (R) to obtain V _R. It is stored (step S16).

Incidentally, in step S16, the correction coefficient K ₁
˜K ₄ need not all be multiplied, but at least one needs to be used.

Then, a set value is set in a built-in timer counter for generating an overspeed warning for a predetermined time (step S17).

[0062] After this, when comparing determines the allowable speed V _R stored in the host vehicle speed V and step S16 read at step S3 (step S18), and it is V> V _R was found, the current timer counter Is "1" (step S19), when it is not "1", the value of the timer counter is decremented by "1" (step S20), and when it is "1", the value of the timer counter is "1". It is reset to 0 "(step S21), and an alarm signal is given to the alarm device 4 via the output circuit 58 (step S22).

[0063] When it is found to be V ≦ V _R in step S18, it resets the timer counter "0" (step S23), and do not give an alarm signal from the output circuit 58 to the alarm unit 4 (step S24).

Further, since the above-mentioned recognition of the radius of curvature of the curve (step S12) is usually performed in an instant, the CPU
Since the recognition value does not exist the next time step S13 is passed due to the processing cycle of 54, step S
25, the value of the timer counter is checked, and if the timer counter value is not "0", steps S18 to S12
2 is executed, and if the timer counter value is "0", the process jumps to step S24 so that no alarm output is generated.

With the above operation, the alarm output operates as follows.

Each time the curve curvature radius display sign of the expressway is recognized once, the own vehicle speed is compared with the previously stored allowable vehicle speed, and if the own vehicle speed ≦ the allowable vehicle speed, no alarm is issued and the own vehicle speed> allowed. In the case of vehicle speed, thereafter, an alarm is issued until the vehicle speed becomes equal to or less than the allowable vehicle speed or a predetermined time elapses after the alarm is issued.

[0067]

As described above, according to the curved road warning device of the present invention, the image signal obtained from the two-dimensional camera for picking up the curve curvature display sign installed on the curved road is binarized. And the radius of curvature of the curved road is detected by collating the character pattern determined by performing the edge processing with the character pattern of the curve curvature stored in advance, and the reference allowable vehicle speed stored in advance is calculated from this curvature radius. When the current vehicle speed is higher than the allowable vehicle speed obtained by multiplying the reference allowable vehicle speed by the correction coefficient corresponding to the vehicle surrounding environment stored in advance, the alarm device is configured to be activated for a certain period of time as an overspeed, so Accurate curve curvature can be obtained before entering a curved road by a simple correction process that takes into consideration, and warning of excess speed when entering a curved road at accurate and appropriate timing. Can be issued, it is possible to contribute to the safe operation of the vehicle.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a curved road warning device according to the present invention.

FIG. 2 is a flowchart showing a processing procedure executed by a control unit used in the curved road warning device according to the present invention.

FIG. 3 is a memory map diagram of a correction coefficient for an allowable vehicle speed used in the curved road warning device according to the present invention.

FIG. 4 is a diagram showing an installation example of a display sign when a vehicle enters a curved road.

FIG. 5 is a diagram showing an example of an image when a curvature display sign of a curved road is photographed by a camera.

[Explanation of symbols]

 1 two-dimensional camera 2 vehicle speed sensor 3 vehicle surrounding environment detection means 31 wiper switch 32 lamp switch 33 load sensor 34 outside air temperature sensor 4 alarm device 5 control unit 52, 55 frame memory 54 CPU 56 memory Shows the part.

Claims (3)

[Claims] 1. A two-dimensional camera mounted on a vehicle for photographing a curve curvature radius display sign of a road, and a vehicle speed detecting means,
A vehicle surrounding environment detecting means, an alarm device, and a character pattern determined by performing binarization processing and edge processing on an image signal obtained from the camera and a character pattern having a previously stored curve curvature radius are collated. By detecting the radius of curvature of the curved road and obtaining a reference allowable vehicle speed corresponding to the previously stored curvature radius of the curve from the allowable vehicle speed obtained by multiplying the reference allowable vehicle speed by a correction coefficient corresponding to the vehicle surrounding environment stored in advance. A signal processing means for activating the alarm device for a certain period of time when the detected vehicle speed is high, and a curved road warning device. 2. The curved road warning device according to claim 1, wherein the means for detecting the vehicle surrounding environment is at least one of a wiper switch, a lamp switch, a load sensor, and an outside air temperature sensor. . 3. The signal processing means stores a memory storing a character pattern of a radius of curvature of a curve and a reference allowable vehicle speed corresponding to the radius of curvature of the curve, and corresponds to a vehicle surrounding environment for correcting the reference allowable vehicle speed. The curved road warning device according to claim 1, further comprising a memory that stores the corrected coefficient.