JPH069075B2 - Multi-lane vehicle detector - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a vehicle detector used, for example, to measure the number of vehicles passing through a road or to measure the traveling speed of the vehicle. The present invention relates to a multi-lane vehicle detector for detecting a vehicle traveling in a lane.

(Summary of the Invention) According to the present invention, when a sensor is configured to detect a vehicle traveling in multiple lanes, the configuration and installation work are simple, and the vehicle detection is good without spoiling the appearance. It is designed to be able to do.

(Prior Art and Problems Thereof) The following are known as conventional vehicle detectors.

(I) First Conventional Example A loop coil is buried under the road surface so as to cover almost the entire width direction of the road, and the impedance change associated with the passage of a vehicle, which is a metal body, is detected on the loop coil, and the impedance is measured. The vehicle detection signal was output based on a predetermined amount of level change due to the change.

(Ii) Second Conventional Example A pole is erected on one of both sides of the road, an arm is extended from the upper end of the pole, and an ultrasonic wave is projected onto the arm and a receiver for receiving reflected ultrasonic waves. The ultrasonic sensor is attached and the vehicle detection signal is output based on the time difference between the time when the ultrasonic wave is transmitted and the time when the ultrasonic wave is reflected depending on whether the ultrasonic wave is reflected from the road surface or reflected from the vehicle traveling on the road.

However, the conventional example having such a configuration has the following drawbacks.

Disadvantages of the first conventional example In order to detect a vehicle accurately with a loop coil, a large one of about 2 m × 2 m is usually required, and this loop coil must be buried under the road surface. There is no choice but to cut the road over a wide area. For this reason, there are drawbacks that it takes time and effort for cutting the road, the period of traffic regulation becomes long, and the construction cost becomes expensive.

Disadvantages of Second Conventional Example Since a large pole is erected on the road, there is a drawback that the installation work is time-consuming and the construction cost is high, similarly to the first conventional example. It had a drawback that it was unaesthetic because it protruded onto the road.

(Object of the invention) The present invention has been made in view of such circumstances, and the installation work can be performed with less labor and at a low cost, and the sensor can be installed without impairing the aesthetic appearance. An object of the present invention is to make it possible to favorably detect a vehicle having a plurality of lanes with a small number and a simple circuit configuration.

(Structure and Effect of the Invention) In order to achieve such an object, the present invention provides a receiving coil having a magnetic body as a magnetic core arranged at a boundary portion between adjacent lanes, and the boundary between the adjacent lanes. A first and a second transmitting coil having a magnetic body as a magnetic core, the high frequency oscillating circuit outputting an exciting current to the first and second transmitting coils, Switching means for outputting an exciting current to the first transmitting coil and the second transmitting coil in a time-sharing manner, an A / D converter for converting a receiving current of the receiving coil into a digital signal, and the switching means. And a CPU for producing and outputting a vehicle detection signal corresponding to the level change of the reception current of the reception coil based on the digital signal.

According to this configuration, based on the switching signal from the CPU,
When the exciting current is output from the high-frequency oscillator circuit to the first transmitting coil and the second transmitting coil in a time-sharing manner, a magnetic field is formed from the first transmitting coil or the second transmitting coil to the receiving coil. This magnetic field induces a current in the receiving coil. When the vehicle approaches the magnetic field, the magnetic flux passes through the vehicle and the magnetic resistance on the receiving coil side decreases, increasing the density of the magnetic flux linking the receiving coil and increasing the receiving current, or eddy current. The level changes depending on whether the receiving current of the receiving coil decreases due to the loss, and in any case, the level of the receiving current changes as compared with the case where the vehicle is not approaching. The CPU creates and outputs a vehicle detection signal corresponding to the level change of the reception current based on the digital signal obtained by A / D converting the reception current of the reception coil, and the vehicles in both lanes based on the time division configuration described above. The approach of can be detected.

Therefore, since a magnetic field is formed between each of the first and second transmitting coils and the receiving coil, each of the first and second transmitting coils and the receiving coil is different from the conventional loop coil. If they are installed in the median strip or on the roadside and the sensor body is installed in one place, it is enough to bury the cable connecting the coil and the sensor body under the road surface. Moreover, even if all of the coils are buried, the space for burying them is small, cutting work on the road can be simplified, installation work can be done with less effort, and the period of traffic regulation can be shortened, and the construction cost can be reduced. It's cheaper.

Further, unlike the ultrasonic type, since the pole is not installed upright, it can be installed without impairing the aesthetics.

Further, in order to detect a vehicle on two lanes, by adopting a time-division configuration, a magnetic excitation current is output to the first and second transmission coils at set time intervals, and the transmission coil on the output side and both lanes are connected. Since the vehicle detection signal can be output from the receiving coil in the state where it corresponds to, and the receiving coil is also used, compared to the case of installing a pair of transmitting coil and receiving coil as a set for each lane, The number of coils can be reduced by one, and vehicle detection in multiple lanes can be performed more inexpensively by reducing the number of constituent members.

Further, since the received current of the receiving coil is converted into a digital signal and digitally processed by the CPU, the circuit configuration for vehicle detection can be simplified and the cost can be further reduced as compared with the case of analog processing. It was

(Description of Embodiments) Hereinafter, the present invention will be described in detail based on embodiments illustrated in the drawings. FIG. 1 is a circuit diagram of a multi-lane vehicle detector according to an embodiment of the present invention, FIG. 2 is a schematic configuration and a perspective view, and FIG. 3 is a schematic plan view showing a circuit installation state. In these figures, 1 is a first transmitting coil and 2 is a second transmitting coil, each of which is wound around a magnetic material such as ferrite as a magnetic core. 3 is a first receiving coil, 4
Is a second receiving coil, and 5 is a third receiving coil, each of which is wound around a magnetic substance such as ferrite as a magnetic core. On a road having four lanes of a first lane R ₁ , a second lane R ₂ , a third lane R ₃ and a fourth lane R ₄ , the first transmission coil 1 has a first lane R ₁ and a second lane R 2. The second transmission coil 2 is embedded in the first boundary R ₁₂ with the lane R _2, and the second transmission coil 2 is embedded with the third boundary R ₃₄ between the third lane R ₃ and the fourth lane R ₄ . Further, the first receiving coil 3 is on the roadside opposite to the first boundary portion R ₁₂ of the first lane R ₁ , and the second receiving coil 4 is on the second lane R ₂
When the second boundary R ₂₃ between the third lane R _3, furthermore, a third receiver coil 5 is embedded respectively in roadside opposite the third boundary R ₃₄ of the fourth lane R ₄ . The first of these
The second transmitting coils 1 and 2 and the first, second and third receiving coils 3, 4 and 5 may be fixedly installed on the road surface.

Reference numeral 6 denotes a sensor main body which houses an electric circuit section, and this sensor main body 6 and the first and second transmitting coils 1 and 2 and the first, second and third receiving coils 3, 4, 5 Are connected via a power transmission cable 6a buried under the road surface.

In the first transmission coil 1 and the second transmission coil 2, a high frequency oscillator circuit (OSC) 7 that outputs an excitation current, a bandpass filter 8 that removes noise components from the excitation current, and the noise components are removed. Excitation means 10 composed of amplification circuits 9 and 9 for amplifying the subsequent excitation current is connected.

The bandpass filter 8 and the amplifier circuits 9 and 9 are connected via a switch circuit 11 as a switching means, and by switching the switch circuit 11, the first circuit is switched to the first circuit as shown in the time chart of FIG. The transmitting coil 1 and the second transmitting coil 2 are arranged to output an exciting current in a time-sharing manner.

Each of the first receiving coil 3, the second receiving coil 4 and the third receiving coil 5 has an amplifier circuit 12 for amplifying a received current, and a bandpass filter for removing a noise component from the amplified received current. 13, and a rectifier circuit 14 for converting the received current into an amplitude signal is connected to each of the bandpass filters 13 ...
Further, a phase comparison circuit (P / D) 15 is connected in parallel to the rectifier circuit 14 to each of the band pass filters 13 ... And a high frequency signal from the excitation means 10 is input to each of the phase comparison circuits 15 ... The phase signals of the excitation current and the reception current are compared and a phase signal is output.

Reference numeral 16 is a multiplexer (MPX), which is an amplitude signal from each of the rectifier circuits 14 ...
… Each of the phase signals from each is input.

Reference numeral 17 denotes a CPU, which outputs a switching signal to the switch circuit 11 and a control signal to the multiplexer 16, and outputs the excitation current from the first transmitting coil 1 in the first and second states. Receiving coils 3, 4
The amplitude signal and the phase signal corresponding to the reception current from the second transmission coil 2 are sequentially output from the multiplexer 16.
While the excitation current is being output from the multiplexer 16, the amplitude signal and the phase signal corresponding to the receiving currents from the second and third receiving coils 4 and 5 are sequentially output from the multiplexer 16.

Reference numeral 18 denotes an A / P converter (ADC) that converts the amplitude signal and the phase signal output from the multiplexer 16 into digital signals and inputs the digital signals to the CPU 17.

The CPU 17 reads the amplitude signal and the phase signal after digital conversion inputted from the A / D converter 18, and based on the both digital signals, the first to the fourth lane R ₁ , from the amplitude change and the phase change. R _{2, R} 3, _{R 4} each vehicle sensing signal (DET1, DET2, DET3, DET
4) is created and output. That is, the first
Taking the case of the lane R ₁ as an example, when the vehicle C approaches the magnetic field formed between the first transmitting coil 1 and the first receiving coil 3 as shown in FIG. , Vehicle C
Magnetic flux concentrates on the metal part of the first transmission coil 1 and the first transmission coil 1.
Mutual inductance with the receiving coil 3 changes,
As a result, the receiving current of the first receiving coil 3 increases,
Based on the change in the level of the received current, a vehicle detection signal corresponding to the change is obtained.

Next, the control operation by the CPU 17 will be described with reference to the flowchart of FIG. 6 and the memory block diagram of FIG.

First, a switching signal is output to the switch circuit 11 to set an excitation current output state to the first transmission coil 1 (F
1) Exciting the first transmitting coil 1. Thereafter, "0" is output to the multiplexer 16 (F2), the amplitude value A1 of the amplitude signal of the first receiving coil 3 is read as the least significant bit (LSB) (F3), and stored in the temporary storage unit A of the memory. To do.

Then, "1" is output to the multiplexer 16 (F
4), the phase value P1 of the phase signal of the first receiving coil 3 is read (F5) and stored in the temporary storage unit P of the memory.

Here, it is determined whether the sensing flag is "1" or "0" to determine whether the sensing is being performed or not (F6). When it is determined that the sensing flag is “1” and the sensing is in progress, step F
7, the read amplitude value A1 and phase value P1
And the value M before sensing as a reference value when sensing is OFF
The difference between A1 and MP1 is calculated, and the difference is compared with the set value. If the difference is within the set value, the sensing is OFF, and if it exceeds the set value, the sensing is not OFF. After that, sense OF
It is judged whether it is F (F8), and when the detection is OFF,
The sensing signal is turned off and the sensing flag is set to "0" (F9). When the detection is not OFF, the second lane R
_The process shifts to the sensing process for ₂ .

When it is determined in step F6 that the sensing flag is not "1", that is, the sensing flag is "0" and the sensing is not being performed, the read amplitude value A1 and phase value P1 are read.
Then, the difference between the values MA1 and MP1 previously stored in the memory is obtained as the reference value when the sensing is turned on, and the difference is compared with the set value (F10). If the value exceeds the set value, the sensing is turned on and the setting is made. If it is within the value, it is determined that the sensing is not ON. Then, it is determined whether the sensing is ON (F11). If the value exceeds the set value, it is determined that it is detected, the detection signal is turned ON, and the detection flag is set to "1" (F1).
2). If it is within the set value, the temporarily stored amplitude value A
1 and the phase value P1 are stored in the memory MA1 and MP1 (F13).

The sensing process for the first lane R ₁ is completed by the above process.

When it is determined in step F8 that the detection is not OFF, after performing the processes of step F9, step F12, and step F13, in any case, the process proceeds to step F14, and the above-mentioned steps F1 to F1 are performed.
Performs the same operation as step F13, performs sensing processing for the second diagonal line R _2.

Thereafter, a switching signal is output to the switch circuit 11 to set a state in which an exciting current is output to the second transmitting coil 2 to excite the second transmitting coil 2, and the third and the third steps are performed by the same processing as described above. Each of the fourth lanes R ₃ , R ₄ is subjected to sensing processing, and the first to fourth lanes R ₁ , R ₂ , R ₃ ,
A vehicle detection signal is generated for all R ₄ , and the vehicle detection signal is output from the CPU 17.

In the above embodiment, the one applied to a road having four lanes in total was shown. However, in the present invention, for example, the first and third receiving coils 3 and 5 on both outermost sides are eliminated and the first and second receiving coils are eliminated.
With the transmitting coils 1 and 2 and the one receiving coil 4,
Detecting vehicles traveling on two-lane roads as a whole, such as two lanes on each side, or one lane on each side, with the median strip as a boundary, and roads with different traffic directions that are adjacent to each other across the median strip. In addition, for example, a vehicle traveling on a road with three lanes in a state where either the first receiving coil 3 or the third receiving coil 5 is lost is sensed. The present invention can be applied to all of the cases where a vehicle traveling on a road having a plurality of lanes adjacent to each other is sensed.

Further, these sensors may be installed at a set distance in the vehicle running direction, and the sensing time difference may be divided by the set distance to measure the running speed of the vehicle.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a multi-lane type vehicle sensor according to an embodiment of the present invention, FIG. 2 is a perspective view of a schematic configuration, FIG. 3 is a schematic plan view showing an installation state, and FIG. 4 is a time chart. 5, FIG. 5 is an explanatory diagram of the vehicle sensing action, FIG. 6 is a flowchart for explaining the control operation of the CPU 17, and FIG. 7 is a memory block diagram. 1,2 ... transmitter coil, 3, 4, 5 ... receiving coil, 7 ... high-frequency oscillator, a switch circuit as 11 ... switching means, 17 ... CPU, 18 ... A / D converter R _{1, R} 2, R ₃ , R ₄ ... Lane, R ₁₂ , R ₂₃ , R ₃₄ ... Boundary.

Claims (1)

[Claims] 1. A receiving coil having a magnetic body as a magnetic core, which is arranged at a boundary between adjacent lanes, and a magnetic body having a magnetic body arranged on a side opposite to the boundary between adjacent lanes. And a high-frequency oscillation circuit that outputs an exciting current to the first and second transmission coils, and a time that is contradictory to the first transmission coil and the second transmission coil. Switching means for outputting an excitation current in a divided manner, an A / D converter for converting a reception current of the receiving coil into a digital signal, a switching signal for outputting to the switching means, and the reception signal based on the digital signal. Vehicle detector with a multi-lane support, which includes a CPU for generating and outputting a vehicle detection signal corresponding to a change in the level of the received current of the vehicle coil.