JPH081680B2 - White line recognition method and device on road - Google Patents

Description

The present invention relates to a method and apparatus for detecting left and right white lines on a road and recognizing whether a vehicle is abnormally displaced from the center of the two white lines. Is.

"Prior Art" Conventionally, various researches on a recognition system of a state of a road have been attempted both in Japan and overseas for automatic driving of a vehicle or assistance for a driver. Many of them have a standard TV scan or a similar TV camera installed in the vehicle
It is intended to convert the video signal of the driving route from the camera from analog to digital, and to perform image processing with an electronic computer, extract the necessary information from it, and use it as a signal for automatic driving, alarms, etc. .

"Problems to be solved by the invention" However, in such a method, the device is extremely complicated,
It becomes expensive and amounted to even 2 ^32-bit / sec data of TV image black and white, examines the relationships between them, and extracts the information sought, was not easy to straining further facilities operations.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus capable of detecting a white line on a target traveling road by a simple system and recognizing displacement of a vehicle.

"Means for Solving the Problems" The present invention is a method for detecting a white line provided along a traveling path by a TV camera attached to a vehicle, and obtaining position information of the vehicle from information of the white line, The photocathode of the TV camera is trapezoidally or triangularly scanned in accordance with the change in the distance formed by the two white lines according to the distance of the traveling path, and the video signal on each scanning line is integrated and the integrated value is used. This is a method of recognizing a white line on a traveling road, characterized in that the position of the white line is detected.

"Operation" When a TV camera is installed slightly above the front end of the vehicle and the running path is observed, the two white lines on the left and right in the video signal have a wide space near each other and become narrower as they become farther away, resulting in a trapezoidal or triangular shape. Become. In order to extract this white line with a high S / N ratio, if the horizontal scanning line is scanned along this white line, the integrated value of the analog video signal will be larger than the part without the white line. Therefore, the horizontal scanning line is scanned along the white line, that is, in the trapezoidal or triangular shape. To do that, the X and Y axes
The scanning method is such that it rotates 90 degrees and the horizontal scanning line converges at a certain point. Then, it is recognized whether or not it is a white line based on the magnitude of the integrated value of the image information of the horizontal scanning line.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

When a TV camera is installed slightly above the tip of the vehicle and the running path is projected, the reproduced image is two white lines (1) (1) and the scenery (2) (2) on both sides of the white line, as shown in FIG. And are displayed as an image. In order to efficiently extract only the target white line information in this image, the following three conditions are required to be satisfied.

The white lines (1) and (1) on both sides are basically trapezoidal (or 3
Square).

It is necessary to extract the information of this trapezoidal (or triangular) white line (1) (1) with a high S / N ratio.

The information (horizontal line part) of the landscapes (2) and (2) outside the white lines (1) and (1) is unnecessary and is not captured as information.

To obtain the information that satisfies the above, Fig. 5 (a)
As shown in (b) and (c), the X axis parallel to the horizontal scanning line (H) and the Y axis parallel to the vertical scanning line (V) are rotated by 90 degrees. Further, the horizontal scanning line (H) is a trapezoidal scanning in which the horizontal scanning line (H) converges to a certain point as shown in (b) or (c). A more detailed description will be given with reference to FIG.

(1) White line (1) on the horizontal road surface (1) Trapezoidal shape of (1), that is, the length at the lower side (short distance) (l ₁ ), the length at the upper side (long distance) (l ₂ ), up and down The height (h) between the sides is uniquely determined and invariable if several parameters such as the mounting position of the TV camera, the height from the road surface, the field of view of the lens, and the forward tilt angle are determined.

(2) When the information of the white line (1) (1) is extracted with a high S / N ratio, if it is attempted to be detected by the differential processing of the analog signal of the scanning line that crosses the white line (1) (1), it will be on the same scanning line. I can't tell the difference from the information of a white object. Therefore,
White line (1) If a scan line is run along (1) and all analog information on that scan line is integrated, the white line (1)
Even if (1) is faint or discontinuous, it can be clearly distinguished from the information of other partial white objects.

A circuit invented in view of the above idea is shown in FIG.

In FIG. 1, (5) is a TV camera including an image pickup tube, and this TV camera (5) includes a lens (6), a photocathode (7), a horizontal (X axis), and a vertical (Y axis) deflection coil (8). )
(9) is provided. The output side of the TV camera (5) is connected to the monitor TV (4) via a video amplifier (10) and a process amplifier (11). The horizontal and vertical deflection coils (8) (9) are coupled to a deflection coil controller (12). (13) is a sync signal generator, and (14) is a power supply.

The deflection coil controller (12) comprises a rotary raster generator (15) for rotating the X-axis and the Y-axis by a predetermined angle θ and a trapezoidal raster generator (16) for converting a rectangular scan into a trapezoidal scan. The schematic circuit is shown in FIG.
Of these circuits, the rotary raster generator (15)
The present invention utilizes the invention of Japanese Patent Publication No. 56-24434 previously proposed by the applicant. In this rotary raster generator (15), (17) is a cosine wave input terminal, (18) is a sine wave input terminal, (19) is an amplifier, (20) (21) (22) (23) is an integrator, and ( 24) (25) is an adder, (26) is an X-axis output terminal, (27) is a Y-axis output terminal, (28) and (29) are switches that are reset by a horizontal synchronizing signal (HD), (30 ) (3
1) is a switch that is reset by the vertical sync signal (VD).

In the trapezoidal raster generator (16), (32)
(33) is a sample-hold circuit, (34) (35) is an integrator, (36) (37) (38) (39) are switches reset by HD, (40) (41) are variable resistors for tilt adjustment Is. The other integrator (35) is an adder (43) consisting of a resistor.
To the X-axis output terminal (26) and one integrator (34) to the Y-axis output terminal (27) via the adder (42).

 Next, the operation of the above circuit will be described.

The white line (1) (1) on the road is imaged by the TV camera (5). Then, the two white lines (1) and (1) are displayed in a trapezoidal (or triangular) shape in a normal state, as the distance becomes narrower as the distance increases as shown in FIG. Therefore, in the present invention, the X axis and the Y axis are rotated by 90 degrees, and the horizontal scanning line (H) is controlled so as to scan on the white lines (1) and (1). Here, since the rotation angle θ = 90 degrees, in the rotary raster generator (15), sin θ = 1, cos θ = 0
Then, the output waveform of FIG. 3 (a) is output to the output terminal (a) of the integrator (20), and the output waveform of FIG. 3 (d) is output to the output terminal (d) of the integrator (21). Waveform appears. In the trapezoidal raster generator (16), the output at the output end (a) is sent to the integrator (34) via the sample-hold circuit (32) and the angle adjusting variable resistor (40), and the output end The output at point (b) is added to the output at point (a) above,
The output waveform of FIG. 3 (c) appears at point (c), and Y
Added to the axial deflection coil (9). Since cos = 0, there is no output from the integrators (22) and (23), and therefore there are no outputs from the sample hold circuit (33), variable resistor (41), and integrator (35). The output at point d) is directly applied to the X-axis deflection coil (8). Thus, when the output waveform (c) is applied to the Y-axis (vertical) deflection coil (9) and the output waveform (d) is applied to the X-axis (horizontal) deflection coil (8), as shown in FIG. The axis and the Y-axis rotate 90 degrees, and the horizontal scanning line (H) becomes vertical. Here, the variable resistor (40) adjusts the trapezoid, that is, the inclination of the white line (1). The inclination is minimum (substantially parallel) as shown in FIG. When the resistance value is maximum, the scanning is performed so as to converge on one point having the maximum inclination (triangle) as shown in FIG. Video signals from this trapezoidal scanning are video amplifier (10), process amplifier (11)
Sent to the monitor TV (4) via. This monitor TV
By performing the normal rectangular scanning by (4), as shown in (d), the white lines (1) and (1) are displayed at the same intervals both near and far.

Next, as shown in FIG. 6 (a), the video signal obtained by the trapezoidal scanning of the horizontal scanning line (H) is obtained when a continuous white line is scanned (a) and when an intermittent white line is scanned (a ) Has many white components. Other than the white line, the white component is small, and the characteristic is (c). Therefore, as shown in (b), the potential value (V ₁ ) when all the video signals of the horizontal synchronizing signal are integrated is detected, and when it is a certain value (Vr) or more, it is recognized as a white line.

As shown in FIG. 7, the relationship between the position of the TV camera (position of the vehicle) and the position of the white line is the distance (d ₁ ) (from the vertical sync signal (VD) to the white line (1) ( ₁ ) ( It can be known by knowing d ₂ ). That is, the position of the TV camera (5) is considered to be the center line (CL) of the two VDs regardless of the positions of the white lines (1) and (1), and therefore the TV camera (5) is brought close to the left white line (1). For example, one distance (d ₁ ) is large and the other distance (d ₂ ) is small. In order to measure this distance (d ₁ ) (d ₂ ), the integrated value (V ₁ ) of the horizontal scanning line is shown in FIG. 7 (c).
Changes from the left VD to the white line on the left (1)
Time until the data of appears and the white line on the right (1)
You can measure the time to VD on the right side of. Then, when there is an unacceptable difference between the distances (d ₁ ) and (d ₂ ) based on these times, the lamp, the buzzer, etc. can be operated.

Next, the white lines (1) and (1) on the road may not be straight lines but may be curved as shown in FIG. 8 (a). In order to know this curving direction, for example, five zones (Z ₁ ) ~
Divide into (Z ₅ ). Then, for each zone (Z ₁ ) to (Z ₅ ), the envelope of the integrated value as shown in (b) is obtained. Then, it is detected in which direction the peaks (P ₁ ) (P ₂ ) of these envelopes are inclined. This operation and the measurement of the time difference can be performed by analog integration and addition / subtraction as described above, but the scanning line number can be digitally added / subtracted. Based on the white line position data at this time, the inclination of the entire trapezoidal raster is controlled so that the white line is as parallel to the scanning line as possible and the S / N ratio is maximized. That is, the angle can be newly set within the time of the vertical blanking period.

Furthermore, in the first field of the time division, the first zone (Z ₁ ) is measured and set to the most suitable angle, then the angle is set to the second zone (Z ₂ ), the third zone (Z ₃ ) ... Can also be set. In this case, it takes 5/60 sec to get the whole zone, but there is no problem in practical use.

Although the image pickup tube is used for the TV camera in the above-mentioned embodiment, practically it is necessary to solidify the sensor in terms of reliability, downsizing and weight reduction, and cost. For this purpose, as shown in FIG. 9, a trapezoidal transfer type photodiode array (for example, CCD) which is preliminarily matched with the inclination of the white line may be used to couple this output to the video signal processing device (51). . In this way, the shape and rotation angle of the raster cannot be freely changed electrically, but the adjustment point is unnecessary and the operation is stable.

When the white lines (1) and (1) are curved, the detected position signal is used to mechanically control the rotation of the photodiode array.

[Advantages of the Invention] Since the present invention is configured as described above, the white line on the road on which the vehicle travels can be reliably detected by a simple method. In particular, even if the white line is partially soiled or has a broken line, it can be clearly distinguished from a partial white object by running a scanning line along the white line and integrating all the video signals. Further, since information such as unnecessary scenery outside the white line is not captured from the beginning, the processing after capturing the white line information signal is also simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the apparatus according to the present invention, FIG. 2 is a detailed electric circuit diagram of essential parts, FIG. 3 is a waveform diagram of each part, FIG. 4 is a projection diagram by a TV camera, and FIG. 5 is X,
FIG. 6 is a waveform diagram between horizontal scanning lines, FIG. 7 is a waveform diagram between vertical scanning lines, and FIG. 8 is an explanatory diagram of curve detection of a white line. FIG. 9 is a front view of the solid-state image sensor. (1) ... White line, (4) ... Monitor TV, (5) ... TV camera, (7) ... Photoelectric surface, (8) ... Horizontal deflection coil,
(9) ... vertical deflection coil, (12) ... deflection coil controller, (13) ... synchronization signal generator, (15) ... rotating raster generator, (16) ... trapezoidal raster generator.

Claims (2)

[Claims] 1. A method for detecting a white line provided along a traveling road by a TV camera mounted on a vehicle and obtaining position information of the vehicle from the information of the white line, which corresponds to the distance of the traveling road. The photocathode of the TV camera is trapezoidally or triangularly scanned corresponding to the change in the interval formed by the two white lines, the video signals on the respective scanning lines are integrated, and the white line position is detected by the integrated value. A method for recognizing a white line on a road, characterized in that 2. A device for detecting a white line provided along a traveling path by a TV camera attached to a vehicle and obtaining position information of the vehicle from information of the white line, wherein a deflection coil of the TV camera is provided with: A deflection coil controller is coupled to the deflection coil controller, which rotates the X and Y axes by 90 degrees and converts the horizontal scan line into a trapezoidal or triangular scan along the white line. A white line recognizing device on a traveling road, which comprises a trapezoidal raster generator.