JP2709995B2 - Vehicle detection device and traffic volume measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle detecting device and a traffic measuring device.

[0002]

2. Description of the Related Art When a vehicle moving on a road is detected or a traffic volume is measured based on a result of the detection,
For example, as shown in JP-A-3-6799, a laser beam, a microwave radar, an ultrasonic sensor, or the like is used to emit various light beams toward a moving body, and the reflected waves are detected to detect a vehicle. There is one that detects the presence or absence. Then, the traffic volume can be measured from the number of vehicles passing (detecting) within a predetermined time.

Further, as disclosed in Japanese Patent Application Laid-Open No. 2-244299, a loop coil is buried in the ground, and a change in inductance of the loop coil which occurs when the vehicle passes above the loop coil is detected, whereby a vehicle is detected. There is also a device that detects the passage of traffic.

[0004]

However, the above-mentioned conventional vehicle detection / traffic volume measuring devices have the following problems, and none of them are satisfactory. That is, in the former case, if there is rainfall, snowstorm, dense fog, or the like, the measurement error becomes large, so that there is a problem that the measurement is affected by the weather and data in bad weather cannot be obtained.

[0005] In the latter case, it is necessary to bury the loop coil in the ground, so that the road is once dug up while the traffic of the vehicle is interrupted, and the loop coil is installed and buried. Once installed, it is not easy to change the installation position, and it is necessary to always install a new loop coil. Therefore, such an operation is complicated, and the installation place is limited to a special place such as a passageway of a parking lot, so that it is practically impossible to measure the traffic on a general road.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned background, and an object of the present invention is to make it possible to relatively easily move an installation place, and furthermore, it is not affected by the weather, and has a general purpose. It is an object of the present invention to provide a vehicle detection device and a traffic volume measurement device that can detect a vehicle traveling on a road.

[0007]

In order to achieve the above object, a vehicle detecting device according to the present invention is installed on a side of a road.
Is a magnetic detector for detecting a unique magnetism moving body has, from the change in the output of the magnetic detection device with the movement of the moving body, means for detecting a maximum value and a minimum value detection means for the detection Means for judging the presence or absence of a vehicle from the result. Then, the means for judging is not more than
The difference between the pair of local maximum and local minimum in
Is configured to determine that the vehicle has passed if it is above
Was .

Preferably, a means for calculating a difference between a maximum value and a minimum value detected by the detection means, and a determination means for determining a type of the moving object vehicle based on the calculated difference. It is to have.

Further, a traffic flow measuring device according to the present invention includes the vehicle detecting device having the above-described configuration, a unit for storing an output of the vehicle detecting device, and a timer unit. The output from the vehicle detection device during the time is stored in the storage unit.

[0010]

Each vehicle has its own magnetic field. When the vehicle moves, it approaches the magnetic force detecting device and then moves away, so that the magnetic force detected by the magnetic force detecting device changes with the movement. . Then, pair a certain period of time or more of the maximum value and the minimum value and always has one vehicle to pass through
Occurs within. Therefore, by detecting such a pair,
The passage of the vehicle is detected. And constitute such a pair.
If the difference between the maximum value and the minimum value is small,
high. Therefore, the pair whose difference is more than a certain level
By judging that the vehicle passed only after there was,
The vehicle can be accurately detected with a simple configuration. In addition, the magnitude of the intrinsic magnetic field of the vehicle corresponds to the size of the vehicle, and becomes larger as the size of the vehicle increases. Therefore, the difference between the maximum value and the minimum value is determined, and if the difference is large, it can be determined that the vehicle is a large vehicle, and the type of the vehicle is determined.

Further, by operating the above-mentioned vehicle detecting device based on a signal from the timing device and storing the detection result in the storing device, the number of vehicles passing within a predetermined time, that is, the traffic volume can be measured. Is done. When the data is stored, the type of the vehicle is also stored, so that the traffic amount of each type of the vehicle and the ratio of the type of the vehicle to the total number of vehicles passing through the vehicle are investigated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a vehicle detecting device and a traffic volume measuring device according to the present invention will be described in detail below with reference to the accompanying drawings. The process leading to the creation and the underlying principles will be described.

First, as shown in FIGS. 1 and 2, the vehicle 1, which is a moving body, is made of a metal such as iron, and is magnetized by various magnetic fields existing on the earth. The direction of the magnetization is oriented in various directions depending on the parking / stop position of the vehicle 1 and the movement route, and the magnitude thereof depends on the amount of metal such as iron, that is, the size of the vehicle 1. The magnetization can be considered as a dipole 2 which is a magnetic dipole. The center O of the vehicle 1 and the center of the dipole 2 coincide with each other, and the dipole 2 is oriented in the direction of the magnetization.

The natural magnetic field 3 generated from the vehicle 1 is represented by a spherical magnetic field uniformly generated in the direction of the axis of the dipole 2 around the center O of the vehicle 1 in the first order approximation. In FIG. 2, the eigenmagnetic field 3 is shown on only one side of the dipole 2 for convenience, but an eigenmagnetic field is also generated on the opposite side so as to be line-symmetrical about the dipole 2. In this specification, for convenience, the dipole 2
A plane passing through the center O and perpendicular to the N and S poles is called a dipole equatorial plane 4, and the periphery of the dipole equatorial plane 4 is a dipole equator 5. Focusing on a point P that is separated from the center O of the vehicle 1 by a predetermined distance in a predetermined direction, the distance from the center O to the point P is represented by r, and a line connecting the center O and the point P, and the dipole equatorial plane 4 Is the dipole latitude. At this point P, a magnetic force detector 7 constituting a vehicle detection device according to the present invention described later is installed.

When defined as described above, the line of magnetic force at the point P is represented by the following relational expression: r = b · cos ² φ (1) Here, b is the distance from the center O until the magnetic field line 3 crosses the dipole equatorial plane 4.

The magnetic potential V of the dipole 2 at the point P is represented by the following equation.

[0017]

(Equation 1) Then, the component Z in the anti-radial direction of the magnetic field (the magnetic field component from the point P to the center O) is given by taking the center direction of the dipole as positive.

[0018]

(Equation 2) Given by The tangential component H at the point P is
It is on the meridian 6 passing through the point P (tangential direction) and faces the direction of the north pole, and is given by the following equation.

[0019]

(Equation 3) Then, the total magnetic force F obtained by combining the two magnetic field components is F = (H ² + Z ² ) ^1/2 (5), and the inclination I of the total magnetic force F with respect to the magnetic field component Z is
X is given by tan IX = Z / H = 2tan φ (6)

Next, the effect of the characteristic magnetic field 3 at the point P generated from the moving vehicle 1 will be considered. here,
First, as shown in FIG. 2, XY coordinates are defined for convenience. That is, the traveling direction of the vehicle 1 is set to the Y axis, the forward direction of the traveling direction is negative, and the rear direction is positive. The direction orthogonal to the traveling direction of the vehicle 1 is defined as the X axis, and the right hand is negative and the left hand is positive toward the traveling direction. The intersection of the two axes is the center O of the vehicle 1. In other words, the XY coordinate axes sequentially change as the vehicle 1 moves.

An angle formed by the X axis and the dipole equatorial plane 4 is defined as a bias angle B, and the sum of the dipole latitude φ and the bias angle B, that is, a line connecting the X axis and the center O of the vehicle 1 to a point P If the angle to be formed is θ, the coordinates (x, y) of the point P on the XY coordinates can be obtained by the following equation.

X = r · cos (φ + B) = r · cos θ y = r · sin (φ + B) = r · sin θ ⁽⁷⁾ Next, when the magnetic force detector 7 is placed at the point P, Consider the output of the magnetic force detector 7. Now, the magnetic force detector 7 has a maximum output when it receives a magnetic force in the direction of the arrow N ', and has a minimum output (negative maximum) when it is in the direction opposite to N'.
The output is set to 0 when a magnetic force in a direction orthogonal to N 'is received.

Accordingly, the vehicle 1 in which the bias angle B is magnetized at a predetermined angle moves on the Y axis at a constant speed from the point at infinity and moves further away toward the point at infinity. In this case, the output waveforms of the magnetic force detector 7 are as shown in FIGS. This means that, from equation (5), the x component of the total magnetic force F is

[0024]

## EQU4 ## It is clear from the fact that Fx = F · cos (IX + φ + B) = F · cos (IX + θ) (8) Here, IX is given by IX = tan ⁻¹ (2 tan φ) (9) from equation (6).

As is apparent from FIG.
When the vehicle passes, a pair of the maximum value M1 and the minimum value M2 appears, so that the vehicle can be detected by detecting the pair. As described above, the larger the vehicle, the larger the intrinsic magnetic field of the vehicle, and thus the difference between the maximum value M1 and the minimum value M2 increases. Therefore, by detecting the magnitude of the difference, it is possible to determine the type of the detected vehicle, whether it is a large vehicle or a small vehicle, or the like.

The vehicle detecting device according to the present invention is based on the above-described principle, and has, for example, a configuration shown in FIG. That is, the magnetic force detector 7 converts the magnitude of the detected magnetic force (inherent magnetic field received from the vehicle 1) into a voltage and outputs the voltage. The magnetic force detector 7 sequentially detects and outputs a magnetic force that changes with the movement of the vehicle. Then, the output is input to the local maximum / minimum value detecting means 9 in the arithmetic processing means 8. The maximum value / minimum value detection means 9 detects the maximum value and the minimum value from a series of data that changes with time based on the given data, and outputs the maximum value data and the minimum value data to the next stage. Is input to the vehicle detection / determination means 10.

In this vehicle detection / determination means 10, as shown in FIG. 3, when one vehicle passes, a pair of local maximum value and local minimum value always occurs (the order of generation is not specified). It is determined whether or not there is a maximum value and a minimum value, and if a pair is detected, it is determined that one vehicle has passed. However, some of the detected pairs may have a maximum value and a minimum value due to fluctuations in an external magnetic field other than the intrinsic magnetic field, noise, or the like, or due to movement of a bicycle or the like having a small intrinsic magnetic field that is not to be detected. Pairs can be included. That is, as the accuracy of the magnetic force detector 7 is increased in order to increase the detection accuracy, the possibility of occurrence of a pair of a maximum value and a minimum value for a reason other than the passage of the vehicle 1 increases. However, these unnecessary pairs all have a small magnetic force, and the difference between the paired maximum value and minimum value becomes small. Therefore, in this example, it is determined that the vehicle has passed when there is a pair having a certain difference or more.

In the vehicle detecting / determining means 10,
The type of vehicle detected based on the magnitude of the difference between the maximum value and the minimum value, that is, whether the vehicle is a large vehicle or a small vehicle, can be determined.

Therefore, the vehicle detecting / determining means 10
Then, the difference between the input local maximum value and local minimum value is determined, and if the calculation result is equal to or more than a predetermined value, the vehicle is determined to be a vehicle. In the following cases, it is judged as a small car).

Then, the determination result is output to the output control means 10.
Is displayed and printed on the output unit 12 via the. Further, in this example, the memory 13 is connected to the output control means 10 so that the determination result can be stored. The vehicle detection device according to the present invention is configured as described above. The traffic detection device according to the present invention is connected to the vehicle detection device having the above configuration by connecting time-measuring means as indicated by reference numeral 14 in FIG. A quantity measuring device can be formed.

That is, based on the time signal from the time counting means 14, the arithmetic processing means 8 is operated for a certain period, and the vehicle data detected during that time is temporarily stored in the memory 1.
3 is stored. The vehicle data includes, for example, the number of large vehicles and the total number of large vehicles and small vehicles. Further, it is preferable to store time data together with the information on the number. With this configuration, the total number of vehicles that have passed in a certain period of time and the total number of large vehicles are directly measured, and the total number of small vehicles can be obtained by taking the difference between the two.

Next, the specific operation of the above apparatus will be described with reference to the flowcharts shown in FIGS.

The output of the magnetic force detector 7 is in the range of 0 to 5 V, so that data processing is performed by an 8-bit A / D converter, and various processing is performed based on the converted data. Has become.

First, when the traffic volume is not so large, the direction of the magnetic force detector 7 is set so that the output of the magnetic force detector 7 having a favorable sensitivity is in the vicinity of the middle 2.5V. This 2.5 V is the zero position on the vertical axis in FIG.

When the apparatus is operated, various registers in the arithmetic processing means 8 are initialized, and a parameter CN indicating the total number of small cars and large persons and a parameter CM indicating the number of large cars are set to 0 as initial values. Is reset to Further, a parameter indicating a difference between the maximum value and the minimum value output from the magnetic force detector 7 is set. As this set,
For example, DC = 5 for small cars and D for large cars.
It is assumed that Z = 40 (S100).

Next, the output data of the magnetic force detector 7 is
D-converted to 0 (equivalent to the above 0V) to 255 (5V above)
), And a value obtained by subtracting 128 (corresponding to the above 2.5 V) from the value is read as A, and Y0 = A is set as the initial data (S110).

Next, the flags F1 and F2 indicating the existence of the maximum value and the minimum value are reset to 0. These flags F1, F2
Is set to 1 when a maximum value or a minimum value is found as a result of data processing. Also, M1 = -128 and M2 = 128 are set as initial values of the maximum value M1 and the minimum value M2. In addition, the latest output data detected,
The parameter L indicating that the immediately preceding output data is equal, that is, the degree to which the same data is continuously output, is reset to 0 as an initial value (S120).

When the initial setting of each parameter is completed in this way, the data value A of the current magnetic force is obtained by the same method as in step 110, and Y1 = A (S1).
30). Then, after calculating the difference DY between the latest data Y1 and the previously obtained data Y0, the latest data Y1 is replaced with Y0 (S140, S150). Then, it is determined whether or not DY is not 0. When DY is 0, the output data is not changed at all, meaning that there is no vehicle. Then, when DY is other than 0, that is, when a change in magnetic force occurs and there is a possibility that the vehicle is moving, it is determined whether the DY is positive or negative (S160, S170).

If the value is negative, the detected magnetic force is decreasing, that is, approaching the minimum value, so that the flow jumps to a loop after step 180 for detecting the minimum value. That is, the current latest data is read (Y1 = A) in the same manner as in step 110 and the like, the difference DY from the previous data Y0 is obtained, and the Y1 is replaced with Y0 (S180 to S200).

Next, it is determined whether or not the difference DY is positive (S210). If it is not positive, it can be determined that it is still approaching the minimum value, and in step 220 DY
Is determined to be zero. If the value is zero, the magnetic force does not fluctuate. Therefore, the parameter L is counted up by one, and step 18 is repeated until the value of L exceeds 20.
Returning to 0, the above processing is repeated. And L is 2
If it exceeds 0, the process returns to step 120 to initialize each parameter and to detect the maximum value and the minimum value from the beginning (S230, S240).

If DY is positive in the determination in step 210, it means that the fluctuation of the magnetic force has changed from a decrease to an increase, so that the immediately preceding data Y1 can be regarded as a minimum value. The data Y1 is stored as the minimum value M2, and the minimum value flag F2 is set to 1 (S250). Thereby, the minimum value can be detected.

Then, it is determined whether or not the local maximum value flag F1 is 1. If the local maximum value flag F1 is not 1, that is, if the local maximum value flag F1 is 0, since the local maximum value has not yet been detected, the processing after the step 270 for detecting the local maximum value is performed. Jump to the loop (S260). In this loop, basically, the same processing as the above-described detection processing of the minimum value is performed.
And sets the maximum value flag F1 to 1 (S
270-S340).

Next, at step 350, the minimum value flag F
Judge whether 2 is 1 or not. If the flag F2 is 1, a pair of the maximum value M1 and the minimum value M2 has been detected, and the difference DM between them is obtained. DC) and large vehicles (DZ), and if they are larger, the parameters CN and CM indicating each number are counted up by one, and the process returns to step 120 to initialize predetermined parameters. , For detecting the next vehicle. When the difference DM is equal to or less than a predetermined value, the pair of the maximum value and the minimum value is not determined by the predetermined vehicle. Therefore, without counting up both the parameters CN and CM indicating the number of vehicles or only the CM. , And returns to step 120, and repeats the above processing (S360-S
400).

In the above example, the pattern in which the local minimum value occurs first is used. However, in the case of the pattern in which the local maximum value occurs first, after the determination in step 270,
Contrary to the above, after the local maximum value is detected in the loop from step 270, the local minimum value is detected in the loop from step 180.

By operating the present apparatus for a certain period of time in this way, the total number of vehicles passing near the present apparatus,
That is, the traffic volume is measured.

When the data A is read (steps 110, 130, 180, and 270), not only is the magnetic force data actually read, but also, as shown in FIG. Timing means 14
The reading of the time pulse data B generated from is performed in parallel. Then, when the data B of the time pulse at a fixed interval is detected, the total number CN of large vehicles and small vehicles and the number CM of large vehicles passed which have been measured up to that time are stored in the memory 13, and FIG. The process returns to step 100 in the flowchart shown in FIG. And
Unless data B of the time pulse is detected, FIGS.
Shifts to the next step of each step in the flowchart shown in FIG.

[0047]

As described above, in the vehicle detecting device and the traffic flow measuring device according to the present invention, the characteristic magnetic field of the vehicle is:
Since it changes with the movement of the vehicle, it is possible to detect the vehicle by detecting the local maximum value and the local minimum value, and it is also possible to determine the type of the vehicle. Therefore, by performing the detection operation for a certain period of time and storing the number of detected vehicles, the traffic volume can be easily measured.

For the detection, a magnetic force detecting means installed on the ground and a device for performing a predetermined process on an output signal from the detecting means only need to be provided. There is no need to bury the device in a location, for example, it is only necessary to install the device on the side of the road to be measured. The device is easy to move, and can be moved to a desired position and installed. In addition, since the magnetic force is used as the detection medium, even if it is rainfall, snowstorm, dense fog, etc., it can be measured and is not affected by the weather. Further, since a change in magnetic force is used as a detection medium, accurate measurement can be performed without being affected by an external magnetic field other than a natural magnetic field such as geomagnetism.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the operation principle of the present invention.

FIG. 2 is a diagram for explaining the operation principle of the present invention.

FIG. 3 is a diagram showing a change in magnetic force according to the movement of the vehicle;
(A)-(H) is a graph which shows the difference of the said change which used the magnetization direction of the vehicle as a parameter.

FIG. 4 is a block diagram showing a preferred embodiment of a vehicle detection device and a traffic measurement device according to the present invention.

FIG. 5 is a part of a flowchart for explaining the operation of the present invention.

FIG. 6 is a part of a flowchart for explaining the operation of the present invention, and is a diagram mainly showing the operation of the maximum value / minimum value detection means.

FIG. 7 is a part of a flowchart for explaining the operation of the present invention, and is a diagram mainly showing the operation of the vehicle detection determining means.

FIG. 8 is a flowchart showing data capture and time pulse capture.

[Explanation of symbols]

 Reference Signs List 1 vehicle 3 inherent magnetic field 7 magnetic force detector 9 local maximum / minimum value detecting means 10 vehicle detecting determining means 13 memory

Claims (3)

(57) [Claims] 1. A magnetic force detecting device installed beside a road and detecting a unique magnetism of a moving body , and detecting a maximum value and a minimum value from a change in an output of the magnetic force detecting device accompanying movement of the moving body. And the presence or absence of a vehicle is determined from the detection result of the detecting means.
Means, wherein the means for determining is a maximum value existing within a certain time.
If the difference between the pair of local minima is greater than a certain
Vehicle detector you characterized in that it is determined that has passed. 2. The vehicle according to claim 1, further comprising: means for calculating a difference between the maximum value and the minimum value detected by the detection means; and determination means for determining a type of the moving object vehicle based on the magnitude of the calculated difference. The vehicle detection device according to claim 1. 3. The vehicle detection device according to claim 1, further comprising: means for storing an output of the vehicle detection device; and timekeeping means, wherein the vehicle within a predetermined time measured by the timekeeping means. A traffic flow measuring device in which an output from a detecting device is stored in the storage means.