JPH0136160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle number detection device that detects the number of vehicles passing on a road using ultrasonic waves.

[Conventional technology]

In conventional vehicle number detection devices that emit ultrasonic waves toward the road periodically and receive the reflections when they stop to detect the passing of vehicles, the number of vehicles detected by holding the received signal during the emission period is The number of pulses of the sensing signal was counted to determine the number of vehicles. In order to reduce counting errors, upper and lower limits are set for vehicle counts, and only counts within these limits are considered to be correct counts, and other cases are treated as abnormalities in sensors, etc. .

[Problem that the invention seeks to solve]

However, with such conventional vehicle number detection devices, due to the characteristics of ultrasonic waves, reflected waves may be received even when no vehicles pass due to environmental conditions such as ambient temperature, humidity, and installed objects, and when a vehicle Even when vehicles pass, the vehicle detection signal may stop momentarily, making it difficult to accurately count the number of vehicles. As a result, traffic volume data that differs from the actual traffic volume may be obtained, leading to various problems.

The purpose of the present invention is to eliminate such conventional drawbacks, and the purpose of the present invention is to reduce errors in the number of vehicles and improve reliability by performing signal processing on received signals. The technical challenge is to obtain high vehicle count data.

[Means for solving problems]

As shown in FIG. 1, the first invention of the present application is a vehicle number detection device comprising a vehicle sensing section 2 and a detection signal processing section 3, wherein the vehicle sensing section 2 includes an ultrasonic emitting means A and a wave receiving means B, the ultrasonic wave emitting means A and the wave receiving means B are installed above the road, and the ultrasonic wave emitting means A emits ultrasonic waves every predetermined period τ, and the wave receiving means B emits ultrasonic waves. The detection signal processing section 3 receives the emitted wave, holds the received signal for a predetermined period τ, and outputs a continuous vehicle detection signal while the vehicle passes.The detection signal processing section 3 includes a vehicle identification means C and a vehicle number counting means. D
The vehicle identification means C receives the vehicle detection signal of the vehicle sensing section 2 as input and outputs a vehicle number counting signal, and the vehicle identification means C detects that the vehicle detection signal continues for a first predetermined time T1 or more. (b) If there is a stop within a second predetermined time T2, which is shorter than the first predetermined time T1, the first predetermined time T1 including the stop is exceeded; It outputs a vehicle identification signal indicating that one vehicle is passing, and the vehicle number counting means D counts the number of vehicles passing on the road by counting the vehicle identification signal. 2 is characterized in that a detection signal processing section 3 is connected to the latter stage.

Further, the second invention of the present application provides a detection signal processing section 3 in addition to the vehicle sensing section 2 having the same configuration as the first invention, and the detection signal processing section 3 includes a vehicle identification means C,
Vehicle number counting means D, abnormality identification means E, error number counting means F, error ratio calculation means G and output means H
The vehicle identification means C receives the vehicle detection signal of the vehicle sensing section 2 as input and outputs a vehicle number counting signal, and the vehicle identification means C detects that the vehicle detection signal continues for a first predetermined time T1 or more. (b) If there is a stop within a second predetermined time T2, which is shorter than the first predetermined time T1, the first predetermined time T1 including the stop is exceeded; It outputs a vehicle identification signal indicating that one vehicle is passing, and the vehicle number counting means D counts the number of vehicles passing on the road by counting the vehicle identification signal.
The abnormality identification means E determines that when the vehicle sensing signal (a) stops for more than a first predetermined time T1 and the vehicle sensing signal is given again within a second predetermined time T2, (b) ) within the first predetermined time T1; (c) if there is a stop within the second predetermined time T2, the first predetermined time T1 including the stop has been exceeded; The error number counting means F counts the abnormality identification signal as the number of errors, and the error ratio calculation means G outputs an abnormality identification signal indicating that vehicle detection is abnormal. The ratio between the vehicle count value obtained by the number counting means F and the error number count value is calculated as the error rate α, and the output means H calculates the error rate α obtained from the error ratio calculation means G and a predetermined value. γ, and when the error rate α is less than a predetermined value γ, the vehicle number counting means D outputs the vehicle number count value. It is characterized by being connected.

[Effect]

According to the first invention of the present application having such characteristics, when the vehicle sensing signal has a length exceeding the first predetermined time including the case where the vehicle detection signal stops for a time within the second predetermined time, the vehicle passes. The number of vehicles passing on the road is counted based on this identification. Further, in the second invention of the present application, when a vehicle is detected by the vehicle detection signal exceeding the first predetermined time including the stoppage within the second predetermined time, and when the vehicle detection signal exceeds the first predetermined time, Identifying an abnormality when it does not continue for a predetermined period of time, counting the number of errors based on the identification signal, and determining whether the vehicle number data is a valid value based on the ratio of the detected number of vehicles and the number of errors, The number of units data is output when the error rate is below a predetermined value.

[Explanation of Examples]

Next, embodiments of the first and second inventions of the present application will be described with reference to the drawings. FIG. 3 is a block diagram showing a vehicle number detection device according to the present invention. In this figure, for example, a vehicle sensing section 2 is provided at the tip of a pole 1 shown in FIG. 2, which periodically emits ultrasonic waves toward the road surface and receives reflected wave signals. The vehicle sensing section 2 is the ultrasonic emitting means A described above.
and constitutes wave receiving means B. The reflected wave signal obtained by the wave receiving means B of the vehicle sensing unit 2 is held during the emission period of the ultrasonic wave, and is converted into a continuous pulse when the reflected wave signal is obtained continuously for each emission period. The detected signal is sent to the detection signal processing section 3 as a vehicle detection signal. The detection signal processing unit 3 has a central processing unit (hereinafter referred to as CPU) 4, and storage means consisting of a read-only memory (hereinafter referred to as ROM) 5 and a random access memory (hereinafter referred to as RAM) 6 is connected to the CPU 4. There is. In ROM5
CPU4 arithmetic processing procedures are stored in the RAM
6 includes the number of vehicles that have passed N, the number of errors E, a time buffer M for temporarily storing time data, and first and second predetermined times T1 and T2, which will be described later, for example, 350 mS.
and 150 mS, numerical storage areas α, β, and γ used to measure the quality of vehicle counting, and a timer area T that stores flag F and timer 7 data. Further, a timer 7 is connected to the CPU 4 and provides time data in units of milliseconds, for example, and the calculation results are outputted from an output device 8. Here, the detection signal processing section 3 forms a vehicle identification means C for identifying passage of a signal based on a vehicle sensing signal, and a vehicle number counting means D for counting the number of vehicles, and further includes a vehicle counting means D for counting the number of vehicles. It forms an abnormality identification means E for identifying an abnormality, a counting means F for counting the number of errors, an error ratio calculation means G for calculating an error ratio, and an output means H.

Next, the operation of the vehicle detection device of this embodiment will be explained with reference to the flowchart of FIG. 4 and the waveform diagrams of FIGS. 5 and 6. The numbers shown using lead lines in FIG. 4 indicate the operation steps of the CPU 4, and FIGS. The ultrasonic wave emitting means A of the vehicle sensing unit 2 outputs a periodic pulse signal every predetermined time τ, for example, 33 mS, as shown in FIG. 5a, and as shown in FIG. In this case, a periodic reflected wave signal as shown in FIG. 5b is obtained at the receiving means B during the passage. By holding this reflected wave signal for a period of emission period τ using, for example, an integrating circuit, a continuous vehicle sensing signal as shown in FIG. 5c can be obtained. If the reflected wave signal is interrupted for some reason, an intermittent vehicle sensing signal is obtained as shown in FIG. 5c.

Now, in FIGS. 6a and 6b, when a vehicle sensing signal is applied to the CPU 4 at time _t1 , the timer 7 is started at the rising edge of the signal (step 11) and time measurement is started. Then, in step 12, the fall of the vehicle detection signal is checked, and the time when the signal falls (t ₂ ,
t ₃ ) is the first predetermined time T1, e.g.
It is determined whether it is 350mS or more (step 13).
If the time interval of the vehicle detection signal is longer than the first predetermined time T1 as shown in FIG. Steps 15 and 16). Here, the vehicle speed is v (Km/h), the vehicle length of the vehicle passing on the road is l (m), and the sensing area where the reception signal is obtained based on the ultrasonic wave transmitted by the vehicle sensor 2 is S (m). ), then the time width Ta of the vehicle sensing signal obtained from one vehicle can be determined by the following equation.

Ta=l+S/v×3.6+τ Here, if the vehicle length l is 5m, the sensing area S is 1.4m, and the time width Ta is 350mS, then v is 73Km/h,
The first predetermined time T1 of 350 mS corresponds to a case where a vehicle with a vehicle length of 5 m passes at a speed of 73 km/h. When passing at less than this speed, the first predetermined time T
Since a pulse width of 1 or more is obtained, the number of vehicles passing on the road can be counted.

In addition, when two vehicles pass close to each other, the distance between the vehicles is H (m), the speed is V (Km/h), and the sensing area is S (m).
Then, the following equation holds between the pulse interval Tb of the vehicle sensing signal.

H=v×(Tb+τ)/3.6+S For example, if the pulse interval Tb is 150 mS, which is the second predetermined time T2, and the vehicle speed v is 50 km/h, H is 3.94 m. Therefore, if the vehicle detection signals continue at intervals within this time T2, the detection signals of one vehicle are separated for some reason and are processed as if one vehicle had actually passed. That is, as shown in Figure 6a, the time
If the pulse does not rise within a second predetermined time _T2 , for example, 150 mS after the rise of the vehicle detection signal at t2, it is assumed that one vehicle has passed normally under the vehicle sensing section 2, and the number of vehicles N is determined in step 17. 1 is added to set the flag F to 0, and further, in step 18, the time buffer M is set to 0, and the process ends.

However, as shown in FIG. 6b, the second predetermined time period after the falling of the vehicle detection signal at time _t3
When the vehicle detection signal rises again at time _t4 within 150 mS, flag F is checked in step 19. Initially, the flag F is 0, so in step 20, 1 is added to the error count E, and in step 21, the fall of the vehicle sensing signal is checked. As shown in FIG. 6b, when the vehicle detection signal falls at time _t5 , flag F is set in step 22, and the process returns to step 14, where timer 7 is set.
Restart. Second predetermined time 150mS after time t ₅
If the vehicle sensing signal does not fall within this time, 1 is added to the number N of vehicles that have passed through steps 15 and 16 and steps 17 and 18, and the flag F and time buffer M are set to 0, and the process ends.
However, after time _t5 , a second predetermined time T2 occurs.
If the vehicle detection signal rises again within 150 mS, steps 19 to 22 are repeated. However, in this case flag F
is set, the process of step 20 is not performed, and the number of errors E does not increase.

On the other hand, at times t ₆ , t ₇ , t ₈ in Fig. 6 c, d, and e,
The timer value when the vehicle detection signal falls is the first
is the predetermined time. If it is within 350mS, proceed from step 13 to step 23 and add 1 to the number of errors E.
is added. Further, in step 24, the sum of timer value T and time buffer M is written to time buffer M, and in step 25, timer 7 is restarted, and the rising edge of the vehicle sensing signal and the timer value are checked (steps 26 and 27). . As shown in FIG. 6c, if there is no pulse rise within a second predetermined time T2 of 150 mS after the fall of the vehicle sensing signal at time _t6 , the value of the time buffer M is checked in step 28. In this case, since the value of the time buffer M is less than 350 mS, the process jumps to step 18 and clears the time buffer M to end the process. However, as shown in Figure 6 d and e, the time
After the falling of the vehicle detection signal at t ₇ and t ₈ ,
When the vehicle sensing signal rises again at times t ₉ and t ₁₀ within 150 mS, the program jumps to step 29 and checks whether the vehicle sensing signal has fallen.

When the vehicle detection signal falls again at times t ₁₁ and t ₁₂ , the process returns to step 24 and the timer value T at that time is
The sum of the time buffer and the time buffer is written to the time buffer M. Therefore, the stored value of the time buffer M is the time from time t ₁ to t ₁₁ in FIG. 6 d, and the time from time t ₁ to t ₁₂ in FIG. 6 e. Thereafter, the timer 7 is restarted through the routine described above, and the rising edge of the vehicle sensing signal and the timer value are checked. As shown in FIG. 6e, if there is no rise of the vehicle detection signal within 150 mS after the fall of the vehicle detection signal at time _t12 , the time buffer M is
The value of is checked. In this case, the time difference M
is 350 mS or more, the program jumps to step 17, adds 1 to the number of vehicles N, sets flag F to 0, and then sets the value of time buffer M to 0 in step 18, ending the process. However, as shown in FIG. 6D, when the vehicle sensing signal further rises at time _t13 within 150 mS after time _t11 , the operations of steps 29 to 26 and 27 are repeated. If the vehicle sensing signal does not fall within 150 mS after time _t14 , which is the falling edge of the last vehicle sensing signal, the value of the time buffer M is checked in step 28. In FIG. 6D, the time buffer M stores the time from time _t1 to time _t14 , so the process jumps to step 18 and sets the value of the time buffer M to 0 to end the process.

In this way, even if the signal stops within the second predetermined time T2, if the vehicle detection signal for the first predetermined time T1 or more is continuously sent from the vehicle sensing section 2, the vehicle is detected. It is assumed that it has passed,
If the time is less than the first predetermined time, it is assumed that no vehicle has passed. Further, if the pulse width of the vehicle sensing signal is less than the first predetermined time, or if the vehicle sensing signal stops within the second predetermined time, it is assumed that some abnormality has occurred and an error is counted. Note that the first and second predetermined times T1,
The value of T2 is changed as appropriate depending on the road where the vehicle number detection device is installed and the expected speed of the vehicles, and if the predicted speed of the vehicles is high, a shorter time is set for each. shall be.

Next, in the second invention of the present application, the detection state of vehicle number counting is confirmed, and the confirmation process will be explained with reference to the flowchart of FIG. 7. In the second embodiment, the detection state evaluation routine shown in FIG. 7 is executed every predetermined period of time, for example, every 5 minutes, by means of an interrupt. When this interrupt routine starts, first, in step 30, the ratio between the number of vehicles N and the number of errors E is calculated, and the error rate α is calculated in the RAM 6.
to be memorized. Next, in steps 31 and 32, α
The value of and the values of β and γ are compared. Here, let β be a large value that indicates that the vehicle sensing unit 2 is abnormal (for example,
0.2), and γ is set to a value (for example, 0.03) at which the reliability of the vehicle number detection device is considered to be low. If the error rate α is larger than β in step 31, it is determined that the vehicle sensing section 2 is abnormal and necessary processing is performed (step 33). If the error rate α is between β and γ, it is determined that the number N of passing vehicles measured by this vehicle number detection device has low reliability as data, and, for example, the number N of vehicles and the number of errors E are cleared ( Step 34). If the error rate α is less than or equal to γ, it is determined that the number of vehicles N is reliable data, and processing such as data transmission is performed (step 35).

〔Effect of the invention〕

Therefore, according to the first invention of the present application, it is possible to count the passage of a vehicle even when the reflected wave signal obtained by the wave receiving means of the vehicle sensing section is intermittent for some reason and the vehicle sensing signal is not continuous. It is possible to obtain data on the number of vehicles that is approximately equal to the number of vehicles that actually passed. In addition, in the second invention of the present application, even if a vehicle sensing signal is obtained within the first predetermined time period when counting the number of vehicles, or even if it is longer than the first predetermined time period, the signal within the second predetermined time period is When stopping, the number of errors is counted as an error, so
An abnormality in the detection of the number of vehicles can be determined based on the ratio to the number of vehicles, and highly reliable data can be output. Therefore, it becomes possible to grasp accurate traffic volume.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the functional configuration of the first and second inventions of the present application, Fig. 2 is a layout diagram showing the vehicle number detection device of the invention installed on a pole beside the road, and Fig. 3 is a block diagram showing the functional configuration of the first and second inventions of the present application. A block diagram showing an embodiment of the vehicle number detection device of the present invention, FIG. 4 is a flowchart showing the signal processing operation of the vehicle number detection device of the present embodiment, and FIG. A waveform diagram showing the waveforms of each part, Figure 6 is from the vehicle sensing section 2.
A waveform diagram showing a vehicle sensing signal given to the CPU 4;
FIG. 7 is a flowchart showing the operation for evaluating the vehicle detection state. A...Ultrasonic emission means, B...Wave receiving means, C...Vehicle identification means, D...Vehicle number counting means, E...Abnormality identification means, F...Error number counting means, G...Error ratio calculation means, H...Output means , 2... Vehicle sensing section, 3... Detection signal processing section, 4... CPU, 6... RAM, 7... Timer, 8... Output device.

Claims (1)

[Claims] 1. A vehicle number detection device comprising a vehicle sensing section 2 and a detection signal processing section 3, wherein the vehicle sensing section 2 comprises an ultrasonic wave emitting means A and a wave receiving means B. The ultrasonic wave emitting means A and the wave receiving means B are installed above the road, and the ultrasonic wave emitting means A emits ultrasonic waves at predetermined intervals τ, and the wave receiving means B receives the emitted waves. The received signal is held for a predetermined period τ and a continuous vehicle detection signal is output while the vehicle passes. The detection signal processing section 3 includes a vehicle identification means C and a vehicle number counting means D. , receives the vehicle detection signal of the vehicle sensing section 2 as input and outputs a vehicle number counting signal, and the vehicle identification means C detects when the vehicle detection signal continues for a first predetermined time period T1 or more. (b) If there is a stop within a second predetermined time T2, which is shorter than the first predetermined time T1, the first predetermined time T1 including the stop is exceeded; , outputs a vehicle identification signal indicating that one vehicle is passing; the vehicle number counting means D counts the number of vehicles passing on the road by counting the vehicle identification signal; A vehicle number detection device characterized in that a detection signal processing section 3 is connected to a downstream of the vehicle sensing section 2. 2. A vehicle number detection device comprising a vehicle sensing section 2 and a detection signal processing section 3, wherein the vehicle sensing section 2 has an ultrasonic emitting means A and a wave receiving means B, and the ultrasonic emitting means The means A and the wave receiving means B are installed above the road, and the ultrasonic wave emitting means A emits ultrasonic waves every predetermined period τ, and the wave receiving means B receives the emitted waves and converts the received signal into a predetermined signal. It is held for a period τ and outputs a continuous vehicle detection signal while the vehicle passes, and the detection signal processing section 3 includes a vehicle identification means C, a vehicle number counting means D, an abnormality identification means E, and an error number counting means. It has a means F, an error ratio calculation means G, and an output means H, and receives the vehicle detection signal of the vehicle sensing section 2 as input and outputs a vehicle number counting signal, and the vehicle identification means C receives the vehicle detection signal. (a) If the first predetermined time T1 or more continues; (b) If there is a stop within a second predetermined time T2, which is shorter than the first predetermined time T1, the first When a predetermined time T1 is exceeded, a vehicle identification signal indicating that one vehicle has passed is output in either of the following cases, and the vehicle number counting means D counts the vehicle identification signal. The abnormality identifying means E is configured to count the number of vehicles passing on a road by: (b) When the vehicle detection signal is given again within the predetermined time T2; (b) When the vehicle is within the first predetermined time T1; (c) When there is a stop within the second predetermined time T2, including the stop. When the first predetermined time T1 is exceeded, an abnormality identification signal is output that indicates that the vehicle sensing is abnormal in any of the following cases, and the error number counting means F counts the abnormality identification signal as the number of errors. The error ratio calculating means G calculates the ratio between the vehicle number count and the error number count obtained from the vehicle number counting means D and the error number counting means F as an error rate α. Yes, the output means H compares the error rate α obtained by the error ratio calculation means G with a predetermined value γ, and when the error rate α is less than the predetermined value γ, the output means H compares the error rate α obtained by the error ratio calculation means G with a predetermined value γ, What is claimed is: 1. A vehicle number detection device, which outputs a vehicle number count value, characterized in that a detection signal processing unit 3 is connected to a downstream of the vehicle sensing unit 2.