JPS6261199A - Vehicle sensor highly adaptive to multiple lanes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a vehicle sensor used, for example, to measure the number of passing vehicles traveling on a road or to measure the running speed of a vehicle, and in particular, to The present invention relates to a multi-lane vehicle sensor for detecting vehicles traveling on a road.

(Summary of the Invention) The present invention provides a sensor capable of detecting vehicles traveling on multiple lanes, which is simple in both configuration and installation work, and provides good vehicle detection without spoiling the aesthetics. It was designed so that it could be done.

(Prior art and its problems) The following types of conventional vehicle sensors are known.

(i) First conventional example A loop coil is buried under the road surface so as to cover almost the entire width of the road, and changes in impedance as a metal vehicle passes over the loop coil are captured. A vehicle sensing signal was output based on a predetermined amount of level change due to impedance change.

(11) Second conventional example A ball is set up on one of both sides of the road, and an arm is extended from the upper end of the ball, and the arm is equipped with a transmitter that projects ultrasonic waves and a receiver that receives reflected ultrasonic waves. A vehicle detection signal is output based on the time difference between when ultrasonic waves are transmitted and received when reflected from the road surface and when reflected from vehicles 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 accurately detect a vehicle using a loop coil, a large shield of about 2 m x 2111 is required, and furthermore, this loop coil must be buried under the road surface.
In order to bury it, a wide area of the road has to be cut. For this reason, cutting the road required time and effort, lengthened the period of traffic regulation, and increased the cost.

■Disadvantages of the second conventional example In order to erect a large ball on the road, there is a drawback that, like the first conventional example, the installation work is labor-intensive and the construction cost is high. The problem was that the ball protruded onto the road, spoiling its aesthetic appearance.

(Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to perform installation work with less effort and cost, and also allows the sensor to be installed without spoiling the aesthetic appearance. To provide a vehicle with multiple lanes that can be detected well without any interference and with a simple circuit configuration.

(Configuration and Effects of the Invention) In order to achieve such an object, the present invention provides a receiving coil having a magnetic core made of a magnetic material disposed at the boundary between adjacent lanes, first and second transmitting coils each having a magnetic core made of a magnetic material disposed on the side opposite to the second transmitting coil; and a high frequency oscillation circuit that outputs excitation current to the first and second transmitting coils; a switching means for causing the first transmitting coil and the second transmitting coil to output excitation currents in a time-division manner in a contradictory manner; an A/D converter for converting the received current of the receiving coil into a digital signal; and a CPU that outputs a switching signal to the means and generates and outputs a vehicle sensing signal corresponding to a change in the level 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 excitation 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 generated across the first transmitting coil or the second transmitting coil and the receiving coil. This magnetic field induces a current in the receiving coil. When a vehicle approaches a magnetic field, magnetic flux passes through the vehicle, reducing the magnetic resistance on the receiving coil side, increasing the density of the magnetic flux interlinking the receiving coil, increasing the received current, or causing eddy current. A level change occurs depending on whether the received current of the receiving coil decreases due to the multiplication, and in any case, the level of the received current changes compared to when the vehicle is not approaching. Based on the digital signal obtained by A/D converting the received current of the receiving coil, the CPU creates and outputs a vehicle sensing signal corresponding to the level change of the received current, and based on Moe's time-sharing configuration, it creates and outputs a vehicle sensing signal for both lanes. It is possible to detect the approach of a vehicle.

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 more effective than a conventional loop coil. If they are small enough to be installed on a median strip or roadside and the sensor body is installed in one place, it is sufficient to bury the cable that connects the coil and the sensor body under the road surface. In addition, even if all the coils are buried, the space required for burying them is small, which simplifies the process of cutting against the road, reduces installation work, and shortens the period of traffic regulation. The cost has become cheaper.

In addition, the ball can be placed upright like in the case of ultrasonic type.

Since there is no such thing, it can be installed without compromising the aesthetics.

Furthermore, in order to detect vehicles on two lanes, by adopting a time division configuration, an excitation current is output to the first and second transmitting coils for a set time, and the transmitting coil on the output side and both lanes are connected. Vehicle detection signals can be output from the receiving coil in a compatible state, and the receiving coil also serves as a pair, so compared to installing a transmitting coil and a receiving coil as a pair for each lane, the receiving coil By eliminating the need for a coil on one side, vehicle sensing in multiple lanes can now be performed at a lower cost without incurring company expenses for the component parts.

In addition, 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 made cheaper than analog processing. Ta.

(Description of Examples) Hereinafter, the present invention will be described in detail based on examples shown in the drawings. FIG. 1 is a circuit diagram of a multi-lane vehicle sensor according to an embodiment of the present invention, FIG. 2 is a perspective view of a schematic configuration, and FIG. 3 is a schematic plan view showing an installed 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 core made of a magnetic material such as ferrite. 3 is the first receiving coil, 4 is the second
The receiving coil 5 is a third receiving coil, each of which is wound around a magnetic core made of a magnetic material such as ferrite. On a road having four lanes: a first lane R3, a second lane R1, a third lane R1, and a fourth lane R3, the first transmitting coil 1 is connected to the first lane R3 and the second lane R9. The second transmitting coil 2 is buried in the third boundary R12 between the third lane R1 and the fourth lane R4.
It is buried in 4. Further, the first receiving coil 3 is connected to the first boundary portion R1! of the first lane R! The second receiving coil 4 is located on the road side opposite to the second lane R2 and the third lane R2.
The third receiving coil 5 is buried in the second boundary R23 with the lane R1, and on the road side opposite to the third boundary R34 of the fourth ridge line R4. These first and second transmitting coils 1 and 2 and the first, second and third
Each of the receiving coils and coils 3.4.5 may be fixedly installed on the road surface.

Reference numeral 6 denotes a sensor main body housing an electric circuit section, and the sensor main body 6, the first and second transmitting coils 1.2, and the second and third receiving coils 3.4.5. are connected via a power transmission cable 6a buried under the road surface.

The first transmitting coil l and the second transmitting coil 2 include a high frequency oscillation circuit (O20) 7 that outputs an excitation current, a bandpass filter 8 that removes noise components from the excitation current, and a bandpass filter 8 that removes noise components from the excitation current. Excitation means 10 consisting of amplifier circuits 9, 9 for amplifying the subsequent excitation current is connected to
ing.

The bandpass filter 8 and both amplifier circuits 9 and 9 are connected through a switch circuit 11 as a switching means, and by switching the switch circuit 11, the above-mentioned The first transmitting coil l and the second
The excitation current is caused to be outputted to the transmitting coil 2 in a time-division manner in a contradictory manner.

Each of the first receiving coil 3, second receiving coil 4, and third receiving coil 5 includes an amplifier circuit 12 that amplifies the received current, and a bandpass filter that removes noise components from the amplified received current. 13 are connected to each other, and each of the bandpass filters 13 is further connected to a rectifier circuit 14 that converts the received current into an amplitude signal. In addition, each of the band pass filters 13...
Phase comparator circuit (P/D) l5 in parallel with rectifier circuit 1.4
are connected to each other, and a high frequency signal from the excitation means 10 is input to each of the phase comparator circuits 15, which compares the phases of the excitation current and the received current and outputs a phase signal.

Reference numeral 16 denotes a multiplexer (MPX), which receives both the amplitude signals from the rectifier circuits 14 and the phase signals from the phase comparator circuits 15.

17 is a CPU which outputs a switching signal to the switch circuit 11 and a control signal to the multiplexer 16, and when the excitation current is output from the first transmitting coil l, the first and second Receiving coil 3.4
The multiplexer 16 sequentially outputs an amplitude signal and a phase signal corresponding to the received current from the second transmitting coil 2.
When the excitation current is being output from the multiplexer 16, amplitude signals and phase signals corresponding to the received currents from the second and third receiving coils 4 and 5 are sequentially output from the multiplexer 16.

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

The CPU 17 reads the digitally converted amplitude signal and phase signal input from the A/D converter 18, and based on both digital signals, determines the first to fourth lanes R+, R2 based on the amplitude change and phase change. , R3, R4 respective vehicle sensing signals (DETt, DET2.DET3.D
ET4) and outputs it. That is,
Taking the case of the first lane R1 as an example, as shown in FIG. 5, the vehicle C approaches the magnetic field formed between the first transmitting coil l and the first receiving coil 3 Then, magnetic flux concentrates on the metal parts of the vehicle C, and the mutual inductance between the first transmitting coil 1 and the first receiving coil 3 changes, thereby increasing the receiving current of the first receiving coil 3. Then, based on the level change of this received current, a corresponding vehicle sensing signal is obtained.

Next, the control operation by the CPtJ17 will be explained using the flowchart of FIG. 6 and the memory configuration diagram of FIG. 7.

First, a switching signal is output to the switch circuit 11 to output an excitation current to the first transmitting coil 1 (F
l) Excite the first transmitting coil 1.

After that, output “0” to multiplexer 16 (F2)
, the first receiving coil 3 as the least significant bit (LSB)
The amplitude value AI of the amplitude signal is read (F3) and stored in the partial storage section A of the memory.

Next, output "1" to the multiplexer 16 (F4)
, incorporates the phase value P1 of the phase signal of the first receiving coil 3 (F5) and stores it in the partial storage section P of the memory.

Here, it is determined whether sensing is in progress or not by checking whether the sensing flag is "1" or "0" (F6). The sensing flag is “
1'', if it is determined that sensing is in progress, step F7
, the corrupted amplitude value A1 and phase value PL, and the value MA before sensing as a reference value when sensing is OFF.
The difference between L and MP1 is determined, and the difference is compared with a set value. If it is within the set value, sensing is turned off, and if it exceeds the set value, sensing is not turned off. Then sensing O
To judge whether it is FF or not, F8), when sensing is OFF, turn off the sensing signal and set the sensing flag to “0”.
"Save (F9). If sensing is not OFF, the process shifts to sensing processing for the second lane R2.

In step F6, when it is determined that the sensing flag is not "1", that is, the sensing flag is "0" and sensing is not in progress, the read amplitude value AI and phase value pt,
Find the difference from the value MA11MPI previously stored in the memory as the reference value when sensing is turned on, and compare the difference with the set value (FIO).If it exceeds the set value, then the sensing is turned on, and if it is within the set value. , it is assumed that sensing is not ON. After that, it is determined whether the sensing is ON (Fit). Here, if it exceeds the set value, it is determined that the detection signal is turned on and the detection flag is set to "1" (F12).

If it is within the set value, store the temporarily stored amplitude value A1 and phase value P1 in the memory MAI and MPI (
Fl3).

The above processing completes the sensing processing for the first lane R1.

In step F8, when it is determined that the sensing is not OFF, after performing the processes of step F9, step F'+2, and step F13, the process moves to step F14, and the step F1 described above is executed.
~ Perform the same operation as step P13, and move to the second lane R7.
Performs sensing processing for.

Thereafter, a switching signal is output to the switch circuit 11, the excitation current is set to be output to the second transmitting coil 2, the second transmitting coil 2 is excited, and the third and third transmitting coils are excited by the same process as described above. Sensing processing is performed for each of the fourth lanes R3 and R4, and the first to fourth lanes R+, Rt,
Vehicle sensing signals are created for both Rs and R-, and the vehicle sensing signals are output from the CPU 17.

In the embodiment L, the application is applied to a road with four lanes in total. However, in the present invention, for example, the outermost first and third receiving coils 3.5 are eliminated, and the first and third receiving coils 3.5 are replaced with the first and third receiving coils. 2
With the transmitting coil 1.2 and one receiving coil 4,
It can detect vehicles traveling on roads that have two lanes overall, such as two lanes on each side, or one lane on each side, with a median strip as the boundary and adjacent roads with different traffic directions across the median strip. In other words, it is possible to sense a vehicle traveling on a three-lane road with either the first receiving coil 3 or the third receiving coil 5 missing. This method can be applied to all cases in which vehicles traveling on adjacent roads with multiple lanes are detected.

Alternatively, these sensors may be installed at a set pressure apart in the vehicle running direction, and the running speed of the vehicle may be measured by dividing the sensing time difference by the set distance.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a multi-lane 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 installed state, and Fig. 4 is a time chart. , FIG. 5 is an explanatory diagram of the vehicle sensing action, FIG. 6 is a flowchart explaining the control operation of the CPtJ17, and FIG. 7 is a memory configuration diagram. 1.2... Transmission coil, 3.4.5... Receiving coil, 7... High frequency oscillation circuit, 11... Switch circuit as switching means, 17...
CPU. 18... A/D converter, R,, R,, R3, R4... Lane, RB, R231R34... Boundary part.

Claims (1)

[Claims] (1) A receiving coil whose magnetic core is a magnetic body placed at the boundary between adjacent lanes, and a magnetic core which is a magnetic body placed on the side opposite to the boundary of each of the adjacent lanes. first and second transmitting coils; a high-frequency oscillation circuit that outputs excitation current to the first and second transmitting coils; a switching means for outputting an excitation current; an A/D converter for converting the received current of the receiving coil into a digital signal; and an A/D converter for outputting a switching signal to the switching means and controlling the receiving coil based on the digital signal. A multi-lane vehicle sensor equipped with a CPU that generates and outputs a vehicle sensing signal corresponding to changes in the level of received current.