JPS5911959B2 - Traffic congestion detection method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a congestion level detection method.

It is difficult to obtain the degree of congestion of vehicles traveling on a road from traffic flow information at one point on the road, and traffic flow information from many points over a certain range along the length of the road is required.

As a traffic flow measuring device that collects vehicle information from many points on a road at one location, there is a device that is installed at a position overlooking the road and has a large number of light receiving elements.

The present invention provides a method for detecting the degree of congestion very easily using the above-mentioned traffic flow measuring device.

Hereinafter, the method of the present invention will be explained in detail with reference to the drawings.

Figure 1 shows how the camera of the traffic flow measuring device is installed.

The camera 1 is mounted at a required height position (for example, 6 m) above the road using a support 3 or the like, and within a required range (for example, 6 m) in the length direction of the road.
For example, it is installed so that it overlooks 100 meters).

Inside the camera 1, as shown in FIG. 4, an optical system 4 including a large number of light receiving elements and a lens 5 is provided.

In this example, there are six detection points P1 within the field of view of camera 1.
~ There is P6.

On the imaging plane of the optical system 4 in the camera 1, one pair of light receiving elements ds1.
dR1-dS6. dR6 is located.

These light receiving elements are composed of, for example, photodiodes.

At each detection point (represented by P), as shown in Figure 2,
A set area S and a reset area R are set apart from each other by a required interval l.

A pair of light receiving elements (represented by dS and dR) are these 6
They correspond to areas S and R, respectively.

When the vehicle CA passes the detection point P from the set area S to the reset area R, as shown in FIG.
Then, a vehicle detection signal (image signal) shifted by time t from dR is output.

Here, the rising edge of the output of each light receiving element ds and dR is detected, and the difference between the rising edges of both signals is defined as the detection time t.

Since this detection time t is the time required for the vehicle to travel between the set area S and the reset area R (distance l), the traveling speed V of this vehicle is determined by the following equation.

However, K is a constant. The actual distance traveled by the vehicle during the detection time t is affected by vehicle color, vehicle height, etc., and varies slightly from vehicle to vehicle, and is not actually equal to the above distance l. By imagining a sensing surface at a position above the height, measuring the distance between both plates S and R on this sensing surface, and statistically correcting this distance, the vehicle's running speed can be measured with high precision. It is possible to do so.

Light receiving element dS that detects the set area S and reset area R
The traveling speed of the vehicle may be calculated based on the time difference when these rises reach a required level, instead of the time difference between the rises of the output signals of , dR.

The processing device 2 performs various processes such as measuring the running speed of a running vehicle and detecting the degree of traffic congestion, which will be described later.

With reference to FIG. 4, each light receiving element ds, dR in the camera 1
After the output signal is amplified by an amplifier 6 equipped with an automatic gain control function, it is sent to a multiplexer channel device 7, where the outputs of each of the 12 light receiving elements are sequentially switched and A-D converted. Sent to vessel 8.

The AD converter 8 performs AD conversion on the output of the input light receiving element at a predetermined sampling period (4.8 m5 in this example), and sends the result to a central processing unit (referred to as CPU) 11.

The processing device 2 is equipped with two CPUs 11 and 12.

Based on the data sent from the A-D converter 8, the CPU 11 executes pattern detection processing of the output signal waveform of each light receiving element, running speed calculation processing at each detection point P1 to P6 described above, and the like. - Controls the channel device 7 and A-D converter 8.

Based on the information obtained by the CPU 11, the CPU 12 performs processing for detecting the degree of congestion, which will be described later, and creates necessary traffic flow information and transmits it to the center via the transmission section 17.

Each CPU 11, 12 is provided with a program memory (not shown) storing an execution program, as well as local memo IJ 13, 14 for storing data, respectively. There is a shared memory 15 that can be accessed.

The measured traveling speeds v1 to 6 at each point P1 to P6 are stored in this memory 15.

The display device 16 displays traffic flow information obtained by the CPU 12, such as the degree of congestion.

The processing device 2 is provided with a filter circuit and an amplifier for removing low frequency components of the signal input from the camera 1, but illustration thereof is omitted for the sake of simplification.

The degree of congestion is calculated as follows.

First, traveling speeds v1 to v at each detection point P1 to P6
6 to the required congestion degree judgment speed V a (for example, 20 kI
n/h), and if the traveling speed is less than or equal to this determination speed Va, that point is determined to be a congested point.

Then, the degree of congestion is determined according to the number of congestion points.

Here, the congestion degree is set to three levels from 0 to 2, and these congestion degrees are determined according to the following table.

At your place It is.

For example, it is determined that no=1, n1=2, n2=3, and n3=4.

Further, if the traffic congestion level 2 continues for a certain period of time or more, it is preferable to set the traffic congestion level to 3.

Various constants are stored in advance in the memory 14 in order for the CPUI 2 to execute such congestion level detection processing.

These constants include a congestion degree determination speed Va, constants 03 and no that determine the congestion degree, and a constant m that serves as a reference for determining the duration of the congestion degree 2 in order to determine the congestion degree 3.

Further, a predetermined area of the memory 14 is a point number counter C.
1 and traffic congestion counter C2.

The number of points counter C1 counts the number of crowded points,
The traffic jam counter C2 counts the duration of traffic congestion level 2.

The procedure of the congestion degree detection process by the CPU 12 is shown in FIG.

This process is executed at regular intervals (for example, every 300 m5).

First, the speed v1 of the detection point P1 is read out from the memo January 5 (step 20) and compared with the determined speed Va (step 21).

If the speed ■1 is less than or equal to the speed Va, the contents of the counter C1 are incremented by 1 (step 22), and it is checked whether the determination of step 21 has been completed for the six detection points (step 23).

If the traveling speed exceeds the determination speed Va, the process moves to step 23 without performing the process of step 22.

If the six points have not been completed yet, return to step 20, read the speed at the next point, and repeat the same process.

That is, the speeds (2) to (6) at each point P2 to P6 are sequentially read out and compared with the determined speed Va, and if the speed is less than or equal to the determined speed Va, the counter C1c is incremented by one.

When the above processing regarding the speeds at the six points is completed (YES in step 23), the contents of the counter C1 represent the number of points (congested points) where the measured speed is less than or equal to the determination speed Va.

Next, the contents of the counter C1 are compared with a constant n3 to see if the contents of the counter C1 are greater than or equal to n3 (step 24).

If the number of congested points is n3 or more, the degree of congestion is set to 2 (step 25), and the content of counter C2 is incremented by 1 (step 26). Then, it is checked whether the content of counter C2 has reached a constant m (step 27). ), if the content of the counter C2 is less than the constant m, the counter C1 is reset (step 33) and the process ends.

If the content of the counter C2 is m or more, the traffic congestion degree is set to 3 (step 28), the counter C1 is reset (step 33), and the process ends.

If the content of counter C1 is less than n3 (step 2
4 (NO), the contents of the counter C1 are compared with a constant no (step 29).

If the content of the counter C1 is less than or equal to no, the congestion degree is set to O (Step 30); if the content of the counter C1 exceeds no, the congestion degree is set to 1 (Step 31);
After this, in either case, counter C2 and counter C1 are reset (steps 32 and 33), and the process ends.

As described above, in the present invention, the vehicle running speed at each detection point is measured based on the output image signal of the light receiving element that detects the vehicle at each of the plurality of detection points set over a required range in the length direction of the road. , the vehicle traveling speed at each detection point is compared with the standard speed for determining the degree of congestion, and when the vehicle traveling speed is smaller than the standard speed for determining the degree of congestion, that point is determined as a congested point, and the number of these congested points is counted. However, since the degree of congestion is determined based on the number of congestion points thus counted, the degree of congestion can be accurately detected.

Moreover, since it uses an optical system that includes a plurality of light-receiving elements placed in positions that cover the entire range of the plurality of detection points and detects vehicles at each detection point, vehicle information at many points on the road is used. can be collected in one place and can be easily installed.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the installation status of the camera of the traffic flow measurement device.
Fig. 2 is an enlarged view of the detection point, Fig. 3 is a waveform diagram showing the vehicle detection signal, Fig. 4 is a configuration and block diagram showing the inside of the camera and the processing device, and Fig. 5 is the congestion degree detection processing by the CPU. Flowchart showing the processing steps when executing
It is a chart. 1...Camera of traffic flow measuring device, 2...
・Processing device, 4...Optical system, dsl, dR1~
ds6゜dR6... Light receiving element, P1 to P6...
...Detection point, ■1 to V6... Travel speed,
Va,...Congestion level judgment speed.

Claims (1)

[Claims] 1. For a plurality of detection points set at required intervals along the road over a range of the required length of the road,
Using an optical system including a plurality of light-receiving elements arranged at positions overlooking the entire range of such plurality of detection points and detecting vehicles at each detection point, a method for detecting traffic congestion level consisting of the following steps, each light-receiving element The vehicle running speed at each detection point is measured based on the output image signal of the vehicle. The vehicle running speed at each detection point is compared with the standard speed for determining the degree of congestion. The vehicle traveling speed is lower than the standard speed for determining the degree of congestion. When the number of congestion points is small, that point is designated as a congestion point, and the number of congestion points is counted.The degree of congestion is determined based on the number of counted congestion points. 2. The congestion detection method according to claim 1, which includes the following steps: measuring the duration of a state in which the number of counted congestion points is greater than or equal to a predetermined number; if this duration is greater than or equal to the predetermined time; Increase the traffic congestion level by one level.