JPS6143760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a traffic control system. In a traffic control system, when it becomes difficult or impossible for vehicles to pass on a part of the road due to reasons such as temporary accumulation of water on the road surface due to sudden rain, the condition of the road surface is detected. information is collected at the central traffic control center and used to indicate roads that are impassable. In order to collect such road surface information, it is necessary to install level detectors at many appropriate locations on the road. By the way, many vehicle detectors are installed on roads. Among these vehicle detectors, those that use ultrasonic waves to detect vehicles do not operate after a certain period of time after transmitting the ultrasonic waves in order to eliminate the reverberation of the transmitted ultrasonic waves and the reflected waves from the road surface. The reception gate (detection gate) of the ultrasonic transducer is opened, and the detection gate is closed after a certain period of time has elapsed, and when a reflected wave is received while this gate is open, it is detected by the vehicle. The presence of a vehicle is detected by treating it as a reflected wave. However, the propagation speed of ultrasonic waves varies depending on the ambient temperature and other factors. Also, the height of the road surface fluctuates due to snowfall and other factors. Therefore, if the time the gate is open is fixed based on the propagation speed of ultrasonic waves at a certain reference ambient temperature, for example, if the propagation speed increases due to a change in the ambient temperature, the gate will open. There is a risk that reflected waves from the road surface will be received before the gate closes, and if the propagation speed becomes small, there is a risk that reflected waves from the vehicle will reach the ultrasonic transducer after the gate is closed. be. Therefore, we learned the time required for reflected waves from the road surface to reach the ultrasonic transducer in response to fluctuations in the propagation speed of ultrasonic waves. If the information is identified as coming from a vehicle, the vehicle can be detected accurately. However, in order to do this, it is necessary to constantly know the time it takes for the reflected waves coming from the road surface to reach the ultrasonic receiver. If it were possible to constantly know the time it takes for the reflected waves from the road surface to reach the ultrasonic receiver and be received, it would be possible to output this time and send it to the central control center. When water accumulates on the road surface, the central control center can indicate that the road is impassable. The purpose of this invention is to use an ultrasonic vehicle detector to detect a vehicle by distinguishing waves reflected from the road surface and waves reflected from the vehicle, and to transmit information on the state of the road surface to central traffic without installing a separate level detector. The central control center collects the data stored in a predetermined area sent from the vehicle detector and the vehicle detection signal, and controls the traffic signal lights with a computer based on the vehicle detection signal. To provide a traffic control system that determines impassable areas of roads based on data stored in predetermined areas. In order to achieve the above object, the present invention detects a vehicle using ultrasonic waves. A time determination means for determining the reception time from transmitting the ultrasonic wave to receiving the reflected wave; a comparison means for comparing the data stored in the storage device with the current reception time; When the difference is less than or equal to a predetermined value α, the data in the predetermined area is updated, and the difference is set to a predetermined value β greater than α.
Vehicle detection signal output means configured to output a vehicle detection signal without updating data in the storage device when the above is the case; and means to output the value stored in the storage device in each period of projecting ultrasonic waves. a vehicle detector installed at a predetermined point with a
and a central processing unit that collects data sent from the vehicle detector and vehicle detection signals. The values stored in each predetermined area and vehicle detection signals sent from these vehicle detectors are collected at the central control center, and a computer installed at the central control center controls the traffic signal lights based on the vehicle detection signals. While controlling, impassable areas of the road are determined based on the values (data) stored in the predetermined areas. First, with reference to FIG. 1, the principle of the method for identifying waves reflected from a road surface and waves reflected from a vehicle according to the present invention will be explained. In Fig. 1 A and B, the horizontal axis indicates time. Note that B is the time t′ ₂ and t′ ₅ in A.
FIG. Let P ₁ and P ₂ be ultrasonic pulses transmitted with a period T ₄ , and let T ₁ be the transmission width (pulse width). Taking reverberation into consideration, the reception gate (detection gate) is opened at time t′ ₁ , which is a time T ₂ that has elapsed from the time t′ ₀ at which the wave was transmitted. The time point at which the ultrasonic wave transmitted at time t′ ₀ is received by the transducer is
Let t′ ₄ . It is assumed that the time from time t' ₀ to t' ₄ varies within a range of ±α due to fluctuations in ambient temperature, etc. The value of α can be determined in advance. Further, the determination limit value of the time difference between the reflected wave from the vehicle and the reflected wave from the road surface is assumed to be β. β is a value that determines the vehicle determination limit, and is defined as the time required for an ultrasonic wave to travel back and forth over a distance of 34 cm, which corresponds to the minimum height of a bumper or the like of a vehicle. By determining β in this way, time t′ ₂ is earlier than time t′ ₄ by β.
If a reflected wave has been previously received, it can be determined that this reflected wave is from a vehicle. α and β are defined by L being a predetermined height from the road surface (for α, L=
10cm, β is 34cm at the minimum vehicle height, such as the height to the bumper of a car), and c is the sound speed t.
When (α or β) is time, it is calculated using the speed of sound t=2L/C, and α is approximately 0.6 msec, and β is approximately 2 msec. The values of α and β are determined in advance, and the microprocessor determines the time from transmitting ultrasonic waves to receiving the reflected waves, and the time from transmitting ultrasonic waves until receiving the reflected waves from the road surface. is loaded from the storage area where it is stored, and the difference a between the time and the time until the current reflected wave is received is calculated. If this difference a is less than α, that is, if the time until the reflected wave is received is within the range from time t' ₀ to t' ₃ or t' ₅ , this reflected wave is recognized as coming from the road surface. I can do it. Therefore, data indicating the time from transmitting the ultrasonic wave to receiving the reflected wave at this time is stored in the storage area. At this time, if the time until the reflected wave is received is from t′ ₀ to t″ ₄ , then
Data for this time is stored in the storage area. In other words, the time required for reflected waves from the road surface to be received due to changes in ambient temperature, etc.
Recognizing that it fluctuated in the time from t′ ₀ to t″ ₄ ,
This time is stored in the above storage area. Therefore, the time from the next ultrasonic wave transmission to the reflected wave reception is
It is compared with the time from t′ ₀ to t″ ₄ , and the difference a is calculated. If the difference a is larger than β, the reflected wave is
This means that the reflected wave was received before t′ ₂ , and this reflected wave is determined to be from a vehicle, and a vehicle detection signal is output. Next, a method for determining time t' ₄ in FIG. 1 will be explained with reference to FIG. 2. Figure 2 shows the relative positions of the ultrasonic transducer P and the shafts Q, Q', and the times are t ₁ , t ₂ , ......
The period shall proceed as shown in t ₁₃ . It is assumed that the light is reflected from the vehicle from time t ₁ to t ₃ and from t ₉ to t ₁₂ , and it is assumed that the light is reflected from the road surface at other times. The storage area described with reference to FIG. 1 is one in which the time from time t' ₀ to t' ₄ is initially stored. This is considered to be the time required to receive the reflected wave from the virtual road surface. This virtual road surface must first be determined. In other words, the time from t′ ₀ to t′ ₄ must be determined automatically. First of all, from the moment the vehicle detection device is turned on, the vehicle detects, for example,
The period until 15 units pass the position of this detection device is called the initial state. In this initial state, the time from time t' ₀ to t' ₄ in FIG. 1 is stored in the storage area. First, in the initial state, after first transmitting ultrasonic waves, when a reflected wave is received, the time until this wave is received is stored in the memory area. In FIG. 2, the horizontal axis indicates time, and t ₁ to t ₁₃ indicate each time point and the time until the reflected wave is received at that time point. In other words, for example, t ₁ represents time t ₁ and the time point
Let it represent the length of time t ₁ until the reflected wave is received at t ₁ . As can be seen in Figure 2, the reception time of the reflected waves from the road surface is longer than the reception time of the reflected waves from the vehicle.
Furthermore, there is always a reflected wave from the road surface between vehicles Q and Q'. Note that it takes longer for waves reflected from a road surface to be received than for waves reflected from a vehicle, regardless of the type of vehicle or from which part of the vehicle the waves are reflected. The reflected wave from the road surface is longer than the reflected wave from the vehicle by time β, and the time variation of the reflected wave from the road surface is smaller than α. Based on this point, the time from when the vehicle detection device is turned on until the reflected wave is received at the first time point _t1 is stored in the memory area, and then a at each time point is calculated from time point _t2 onwards. However, if a is less than or equal to α, the data stored in the storage area is updated to the time up to the reception of the reflected wave at that time. However, in this initial state, even if a is larger than α, a
If is smaller than β, the data stored in the storage area is updated to the time up to the reception of the reflected wave at that time. However, if the current wave reception time is shorter than the previous wave reception time and a is larger than β, a vehicle detection signal is output. For example, if a vehicle performs such an operation,
By repeating this process until 15 vehicles are detected, the reference plane, that is, the time it takes for the ultrasonic wave to actually be reflected from the road surface and received, is determined. During the above operation, if a is larger than β, the data in the storage area is not updated. That is, if the time until the current wave reception is shorter than the data stored in the storage area by α or more, the data in the storage area is not updated. As described above, the storage area stores the actual time from when the ultrasonic wave is transmitted until the reflected wave from the road surface is received. If it is output in a periodic manner, it will be sent to the central control center each time, and the central control center will transmit the above information if, for example, there is heavy rain on a certain road and 10 cm of water accumulates on the road surface, and the ultrasonic reflecting surface becomes that high. If the value stored in the memory area is quite small (the time it takes to receive the reflected wave from the road surface is quite short), it is possible to know that there is an abnormality on the road surface and to display a message indicating that traffic is not possible. . FIG. 3 is a block diagram showing the configuration of an example of a device for carrying out the present invention, in which 1 is a pulse oscillator, 2 is a gate for transmitting waves, 3 is an amplifier, 4 is a limiter, and 5 is an ultrasonic wave transmitting/receiving device. Pulses generated by an oscillator 1 are input to a transducer 5 via a gate 2, an amplifier 3, and a limiter 4. 6 is a wave receiving limiter, 7 is a wave receiving amplifier, 8 is a waveform shaping circuit, 9
1 is a detection gate (wave reception gate); 10 is a counter; the received wave output of the transducer 5 is inputted to the counter 10 via a limiter 6, an amplifier 7, a waveform shaping circuit 8, and a detection gate 9; 11 is a clock pulse generator, 12 is an inhibit gate, and the clock pulse from the generator 11 is sent to the counter 10 via the gate 12.
, and the output when the counter 10 counts a predetermined number (for example, 8) is the inhibit input to the gate 12. 13 is a gate. 15 is a microprocessor, which is configured as follows. 16 is ROM (read only memory), which contains the actual program. 1
7 is an arithmetic processing circuit, 18 is an output circuit, 19 is an X register, 20 is a Y register, and 21 is an A register. 22 is RAM (random memory), RAM 2
2 may be included in the microprocessor 15 or may be located outside it. 23 is a program counter, arithmetic processing circuit 1
The arithmetic processing result is input from 7, and a signal is given to the ROM 16 and the arithmetic processing circuit 17. 24 is a control circuit which receives the arithmetic processing results of the arithmetic processing circuit 17, outputs a signal to close the gate 13, and provides a command signal to the controller 25. 2
Reference numeral 6 denotes a register into which predetermined contents of the output circuit 18 are inputted via the controller 25 and transmitted to the central control center. Note that 27 is a line for inputting the output of the counter 10 from the gate 13 to the arithmetic processing circuit 17;
28 is a line for inputting the output of the output circuit 18 to the gate 2, 29 is a line for inputting the output of the output circuit 18 to the gate 2, and 30 is the control circuit 2.
A line for inputting the output of 4 to the gate 13,
31 is a line for outputting the output of the control circuit 24 to the controller 25, 32 is a line for outputting a vehicle detection signal, and 33 is a line for outputting the contents of the register 26. As shown in FIG. 4, the RAM 22 includes a system counter, detection gate rise and fall time settings, α and β settings, reception width settings, reception counter, road surface counter, initial flag, vehicle detection flag, There are various areas such as vehicle counter, vehicle number setting, and code flag. These areas are designated by address designating values set in the X register 19 and Y register 20, respectively. Next, the operation will be explained with reference to the flowchart of FIG. In FIG. 5, the symbols or 〓 attached to the side of each block indicate the number of each step, and below, each step will simply be...
..., written as 〓. In FIG. 5, F ₁ is an initial flag, SC is a system counter, G ₁ is a transmission signal, G ₂ is a detection gate, DS is a detection signal, F ₂ is a code flag, F ₃ is a vehicle flag, C ₁ , C ₂ represents the first and second wave reception counters, CR represents the road surface counter, and RS represents the wave reception detection. First, the power of the device shown in FIG. 3 is turned on to start operation. From this point on, the arithmetic processing circuit 17
It operates according to the program stored in the ROM16. First, turn on the initial flag _F1 in the initial flag area of RAM 22 . Input the values of the items shown in Figure 4, such as the α value and β value set in RAM 22 , from the outside and read them.
Set in each area of RAM 22 .
The system counter SC in the RAM 22 is reset at this point, and the system counter SC starts measuring time from this time. Outputs an output that turns on the transmission signal _G1 . As a result, the output on line 28 of output circuit 18 becomes "H", gate 2 is opened, and oscillator 1
The output of the oscillator 1 is applied to the transducer 5, and the transducer 5 transmits ultrasonic waves based on the output of the oscillator 1. Check whether the system counter SC has reached the transmission width _T1 shown in FIG. This is done by reading the data in the area of the wave transmission width of the RAM 22 into the A register 21 and comparing it with the time value of the system counter SC. When the time value of the system counter SC reaches the transmission width _T1 , the transmission signal _G1 is turned off. As a result, the output of the output circuit 18 becomes "L", and the output of the line 28, which had been "H" until then, becomes "L". When the output of the line 28 becomes "L", the gate 2 is closed, and the output of the oscillator 1 is no longer applied to the transducer 5.
The time value of the system counter SC is the time shown in Figure 1.
See if T ₂ has been reached. Time T ₂ (RAM 22
When the detection gate falls area value) is reached, it outputs an output that turns on the gate signal _G2 . This causes the output circuit 18 to set the signal on the line 29 to "H", thereby opening the gate 9. Even if the transducer 5 receives a reflected wave, the received wave output is not added to the counter 10 until the gate 9 is opened. Check whether reception is detected (RS≠0). This is determined depending on whether the count value of the counter 10 is zero or a certain value other than zero. The inhibition gate 12 is disabled until the count value of the counter 10 reaches a predetermined value, for example 8, and the clock pulse from the generator 11 is passed through the gate 12 to the counter 1.
0, but the counter 10 is added to the transducer 5.
Timing is not performed until the received wave output is added. Note that since the arithmetic processing circuit 17 reads the signal on the line 27 at regular intervals, it does not necessarily read the signal on the line 27 at the moment the received wave output of the transducer 5 is applied to the counter 10; After a slight delay from the time when the received wave output is applied to the counter 10, the signal from the control circuit 24 is transmitted to the line 30.
When the gate 13 is opened, the count value of the counter 10 is input to the arithmetic processing circuit 17 from the line 27. After the received wave output is added to the counter 10, the arithmetic processing circuit 17
When reading the signal on line 27, the count value of counter 10 is a certain non-zero value. In this way, if the count value of the counter 10 is a certain value, it is assumed that reception has been detected (RS≠0), and the first
Create reception counter data _C1 . The time SC from when the ultrasonic wave is transmitted to when it is known that the received wave has been detected is measured by the system counter, but as mentioned above, the time SC is from the time when the received wave output actually occurs. There is a slight delay, and the time equivalent to this delay (this is referred to as RC).
is measured by the counter 10, so the count value of the counter 10 is calculated from the system counter's time value SC.
By subtracting RC, the time C ₁ until the reflected wave is actually received is calculated. This is stored in the wave reception counter area of the RAM 22 as wave reception counter data. Check to see if the reception has gone down (RS = 0). When the received wave is down (RS=0), the received wave output of the transducer 5 disappears, so that the count value of the counter 10 becomes zero. When the count value RC of the counter 10 reaches a certain value and then becomes zero, it is detected that the received wave is down, and the gate signal _G2 is turned off. 18 sets the signals of all output lines to "L". In this case, the signal on the line 28 which had been set to "H" is changed to "L", and the gate 9 is closed. If NO at or, check whether the system counter SC has reached time _T3 at or. As shown in Figure 1, the time T ₃ is based on the assumption that the reflected wave is received from the road surface.
Set it to a time slightly longer than the expected maximum reception time. If there is no reception detection or reception down detection by time T ₃ , it means that some abnormality has occurred and the gate signal is not detected.
Output G ₂ off and move to 〓. The subsequent operations up to 〓 will be described later. , if YES, the difference a from the received wave counter is calculated later. At time t ₁ in FIG. 2, the signal has not yet been entered into the area of the receiving wave counter, so the difference a at this time is equal to the data C ₁ of the receiving wave counter itself created in . Then, enter |a| into the reception counter, and set flag _F2 . We see |a|>α, but
In this case, |a| is naturally larger than α. I look at the received wave counter > received wave counter in Yotsute, but
In this case, the data _C2 of the received wave counter is zero, so naturally the answer is YES. Then, it is checked whether the initial flag _F1 is on, and since it is on at this time, the data _C1 of the wave receiving counter is set in the wave receiving counter. At this point, data is entered into the received wave counter for the first time. Next, the road counter CR
data is output and sent to the central control center. This causes the output circuit 18 to output road surface counter data CR according to a command from the control circuit 24, and the controller 25
This is done by putting this data into register 26. However, in this case, the data has not yet been entered into the road counter, so the data
CR does not exist. Next, check whether n≧N. N is stored in the vehicle number setting area of the RAM 22. For example, if the initial state is until 15 vehicles are detected, the value 15 is stored. n is the actual number of vehicles detected, which is stored in the vehicle counter area of RAM 22 each time a vehicle is detected. Since n is now zero, the answer is NO, so skip 〓 and move on to 〓 to check whether the time value SC of the system counter has reached time _T4 . If the vehicle detection pulse DS is generated when time _T4 is reached, output is output to turn it off using 〓, and the process moves to step 4 to reset the count value SC of the system counter and start time measurement again. Outputs on. In this way, ultrasonic waves are transmitted every time _T4 . When the reflected wave of the transmitted wave at this time is received at time t ₂ , create data for the reception counter, and if the reception is down at , calculate a, and at |a|
Set the received wave counter and set the sign flag with
Stand up F ₂ . F ₂ indicates the sign of a, and it is used to indicate the sign of a each time a is calculated.
Press F ₂ . If a is almost equal to zero at this time, then |a|>α is not, so 〓
Reset the vehicle flag F ₃ with (However, in this case, the vehicle flag F ₃ has not been reset yet, so leave it as is.), set the data C ₁ of the reception counter to the road counter with 〓, and set the data of the reception counter with 〓. Set data _C1 in the reception counter and check n≧N. Since this is NO, go back to 〓, 〓. Then at time t ₃ ,
Create reception counter data with , and if the reception is down with , calculate a with , and |a|
>See α. If |a| > α, it returns to 〓, 〓, or 〓, and during this time, the data of the receiving wave counter is C ₁
is set in the received wave counter and road surface counter. If |a|>α, check whether the received wave counter>the received wave counter. This is YES
, then the initial flag F ₁
Since it is set, the data of the received wave counter is set in the received wave counter. In this way, even if |a|>α is YES at time t ₃ ,
Even if NO, the data of the received wave counter at this time is set in the received wave counter, the data CR of the road surface counter is output at ⓓ, and the process returns via ▼. Next, at time _t4 , a is calculated by the same operation, and |a|>α is found at. Time t ₄
The reflected wave at time t3 is from the road surface, and the reflected wave at time _t3 is from the vehicle, so |a|>α
is YES. Check if the received wave counter > the received wave counter. This is not necessary
Since it is YES, check whether flag F ₁ is set. Since the flag _F1 is 1, the process moves to set the data _C1 of the received wave counter in the received wave counter, and returns to the process through , , and . point in time
At _t5 , create the data of the reception counter at that time, and calculate a. At times t ₄ and t ₅ , the reflected waves are both from the road surface, so
The result of looking at |a|>α is NO. Then, through 〓 (here, there is no operation because the vehicle flag F ₃ has not been set yet), the data C ₁ of the reception counter is set to the road surface counter at 〓.
The data _C1 of the received wave counter is set to the received wave counter, and the data CR of the road surface counter is set at .
is output and sent to the central control center. At that point
At time t ₅ , the data CR of the road surface counter and the data C ₂ of the reception counter become the same, and the data is the same at time t _5.
The data is the same as the reception counter data in .
That is, it is the time required until the reflected wave from the road surface is received at time _t5 . Since the reflected waves from the road surface are obtained from time t ₅ to t ₈ , for a calculated at each time, |a|
>α, the result is NO, so the data of the received wave counter created at each time point is set to the received wave counter and the road surface counter. That is, from time _t5 to time _t8 , the time taken until the reflected wave from the road surface is received is created by the wave reception counter at each time point, and this value is set in the road surface counter and the wave reception counter. In this way, the time until the reflected wave from the road surface is actually received is set in the road surface counter and the wave reception counter at each point in time, and the reception time of the reflected wave from the road surface varies. For example, the data of the road surface counter and the received wave counter are updated accordingly. During such an operation, the data on the road surface counter and the received wave counter are always the same. Assuming that there is a reflected wave from the vehicle at time t ₉ , create data for the wave counter at this time, load it from the wave counter at , calculate the difference a from that data, and then calculate |a| >α, the result is YES. Check if the received wave counter > the received wave counter. In reality, when a is calculated, the value is entered into the reception counter, and the positive or negative sign of a is determined by the RAM 22 in Figure 3.
Since it is placed in the area of sign flag _F2 , the judgment is made by looking at whether the sign of this area is positive or negative. In this case, the data of the received wave counter is smaller than the data of the received wave counter, so a>
Look at β. In this case, since the wave is reflected from the vehicle, a>β. Therefore, the detection signal DS on is output at 〓, and the output of the line 32 of the output circuit 18 is set to "H" to output the detection signal. Check if vehicle flag _F3 is on, because it is NO.
The vehicle counter n is incremented by 1. At this time, n=1. Set (turn on) vehicle flag _F3 with 〓,
Set the data CR of the road surface counter to the reception counter with 〓. That is, when a reflected wave from a vehicle is received, the data of the road surface counter and the wave reception counter are not updated with the data of the wave reception counter at that time. However, since the data of the wave reception counter has been changed to a, the data of the road surface counter is set in the wave reception counter, and this data is used to calculate the data at time _t8 , which is before the time when the reflected wave from the vehicle was obtained. Return to data. point in time
The operation at t ₁₀ is the same as described for time t ₉ . However, since the vehicle flag is already turned on at time t ₁₀ , the process moves to 〓 and 〓 is skipped. Therefore, the vehicle counter will not be incremented twice for the same vehicle. Set the data of the road surface counter (this is the data at time _t8 ) to the received wave counter at . While the reflected wave from the vehicle is being obtained in this way, the data on the road surface counter and wave reception counter are not updated, and in this case, both are set to the time when the reflected wave from the road surface was received at time _t8 . . Note that the vehicle flag _F3 is reset at time _t14 by the same operation as described for time _t5 . When the number of detected vehicles n reaches the set value N (for example, 15) by repeating the above operations, the result is YES, and the process moves to 〓, where the initial flag _F1 is reset. By the time the initial flag _F1 is reset, the time it takes for the reflected wave from the road surface to be received has been repeatedly updated and set as the correct value in the road surface counter and the received wave counter. If a | > α and the received wave counter > the received wave counter, look at a > β, and if YES, a vehicle detection signal will be generated, but if it is NO, the initial flag will be set. Since it is not on, immediately move to 〓 and set the road surface counter to the reception counter. That is, after the initial state ends, if |a|>α and a<β, neither the road surface counter nor the received wave counter is updated. Update is performed only when |a|<α. As described above, when a is smaller than α in the initial state, and when a is larger than α but smaller than β, the data of the receiving wave counter is updated, and the data of the receiving wave counter is updated. This is used as reference data for determining reflected waves from vehicles, but after the initial state has passed, the reference road surface that is the basis of the reference data has already been determined, so the reference data is updated only when a is smaller than α. do. In addition, a receiving wave counter, a road surface counter, and a receiving wave counter are provided, and in the initial state, if a is smaller than α, the data of the road surface counter and the receiving wave counter are updated together, and if a is larger than α and a If the sign of is positive and the magnitude is smaller than β, only the data of the receiving wave counter is updated, and then when the next reflected wave is received, if a is smaller than α, the data of the road surface counter and the receiving wave are updated. Update the data together with the counter. This happens only once due to noise etc., for example, at time _t2 , a becomes β.
Even if it is smaller than α, if this is an error due to noise, a becomes larger than α at time t ₃ , so according to the present invention, the road surface counter is not updated in this case, and the incorrect reference is There is no risk of creating data. In the operations described above, the step below is always executed in any case. That is, 〓 is executed every time ultrasonic wave is transmitted, and in 〓, the data CR of the road surface counter is input from the output circuit 18 to the register 26, and from the register 26 to the line 33.
sent to the central control center. The central control center receives a vehicle detection signal when a vehicle is detected in each cycle of ultrasonic wave transmission, and can perform traffic control based on this signal. FIG. 6 is a graph showing the arrangement of vehicle detectors and variable display boards related to traffic regulations, where 41 is a road, 42 is a vehicle detector, and 43 is a variable display board. As shown in the figure, a large number of vehicle detectors and display boards are installed at appropriate locations on each road. FIG. 7 is a block diagram showing the control system of traffic signal lights and variable display boards by the central control center, in which 51 is a vehicle detector using ultrasonic waves, 52 is a traffic signal light, 53 is a variable display board, and 54 5 is a communication control device, 55 is a computer, 56 is a map board, 5
4, 55, and 56 are installed at the central control center. The vehicle detection signal from the vehicle detector 51 is sent to the central control center, where it is sent to the communication control device 54.
This is received by the computer 55 and inputted into the computer 55. The computer 55 sends out a control signal based on the input vehicle detection signal to control traffic signal lights (not shown in FIG. 6, but provided at each intersection of each road). In this invention, the vehicle detector further transmits road surface counter data for each cycle of ultrasonic wave transmission, and the central control center transmits the data via the communication control device 54.
Road surface counter data is input to the computer 55. The road surface counter data indicates the time until the reflected wave from the road surface is actually received. If water suddenly accumulates on the road surface due to rain or the like, the time until the reflected wave from the water surface is received becomes shorter, and the computer 55 can detect such an abnormality on the road surface. Since a large number of vehicle detectors are installed at important points on the road, the computer 55 can know which part of the road has become impassable due to an abnormality in the road surface. For example, if the road in the lower right area from the dotted line 45 in FIG. display. A map board 56 showing the road 41 shown in FIG. 6 is provided at the central control center, and impassable areas of the road can also be displayed on this map board by an appropriate method.
In addition to displaying on display boards, notifications can also be made through radio broadcasts, etc. As described above, according to the present invention, by installing a vehicle detector using ultrasonic waves, traffic signal lights can be controlled from a central control center and road impassability can be detected without installing a large number of separate level detectors. Areas can be displayed.

[Brief explanation of the drawing]

1 and 2 are graphs for explaining the principle of this invention, FIG. 3 is a block diagram showing the configuration of an example of an apparatus for carrying out this invention, and FIG. 4 is a graph for explaining the principle of this invention.
A graph showing the contents of RAM, Figure 5 is a flowchart, Figure 6 is a graph showing the arrangement of vehicle detectors and variable display boards on roads, and Figure 7 is a graph showing the arrangement of traffic lights and variable display boards by the central control center. FIG. 3 is a block diagram showing a control system. 5...Ultrasonic transducer, 15 ...Microprocessor, 18...Output circuit, 22 ...Storage device (RAM), 51...Vehicle detector using ultrasonic waves,
52...Traffic signal light, 53...Variable display board, 55
...computer.

Claims (1)

[Scope of Claims] 1 Ultrasonic vehicle detectors are installed at a plurality of predetermined points to detect vehicles that transmit ultrasonic pulses toward the road surface at a predetermined period and receive reflected waves of the ultrasonic pulses from the road surface or the vehicle. In the road control system, the signals from the ultrasonic vehicle detectors are collected by the central control device, and the central control device controls the display boards and traffic lights installed corresponding to the road. The device includes a storage means for storing time data from the sending of an ultrasonic pulse until the reflected wave from the road surface is received, and a storage means for storing time data from sending the ultrasonic pulse this time until receiving the reflected wave from the road surface. When the difference between the time and the wave reception time from the road surface stored in the storage means is less than or equal to a first value (α) predetermined for fluctuations in the wave transmission and reception time, it is stored in the storage means. The wave reception time data from the road surface currently measured is updated to the wave reception time data measured this time, and on the other hand, when the difference is greater than the first value, which is predetermined corresponding to the minimum vehicle height from the road surface, means for outputting a vehicle detection signal without updating the storage means when the value is greater than or equal to the value (β) of 2; and a wave reception time from the road surface stored in the storage means for each cycle of the ultrasonic pulse. The central control device is equipped with an output means for outputting data, and on the other hand, the central control device controls traffic signal lights based on the vehicle detection signal, and receives reflected waves from the road surface stored in the storage means of the ultrasonic detector. A road control system comprising a computer that detects that the road surface is abnormal when the time is shorter than the reception time of waves from a normal road surface, and controls the display on the display board when the abnormality is detected. system.