JP2839335B2 - Method for determining vehicle type and measuring speed of traveling vehicle and apparatus therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a traveling vehicle capable of determining the type of a vehicle traveling on a road and simultaneously measuring the speed of the vehicle to obtain more detailed information on traffic conditions. The present invention relates to a method for determining a vehicle type and a method for measuring a speed, and an apparatus therefor.

[Problems to be solved by conventional technology and invention]

The Traffic Control Center, which monitors traffic volume on roads and contributes to smooth traffic conditions, analyzes the traffic volume data automatically sent from vehicle detectors in the traffic control area with a computer, Traffic lights and variable signs are controlled according to the situation, but the traffic data shows that freight vehicles for transporting goods, private cars that account for the majority of traffic, and important public transport The buses that are viewed are all mixed. In order to grasp the traffic conditions of these types of vehicles, a large amount of manpower and days are spent in advance to conduct surveys, and the results are currently used as fixed parameters for traffic control.

Further, the result of the measurement of the speed of the vehicle, which is performed regardless of the type of the vehicle, is also used for appropriate control of a traffic signal.

By the way, if it is possible to send the traffic condition by vehicle type to the traffic control center every moment along with the speed information for each vehicle,
Traffic events such as traffic congestion can be quickly known, and more detailed traffic control can be performed by performing control corresponding to this. In fact, no matter which road you look at, the types of vehicles that travel there are diverse, and their speeds are also different. Deemed sufficient.

Therefore, it is important to determine the type of the vehicle, that is, the “vehicle type”, count the vehicle type, and simultaneously measure the speed of each vehicle. The vehicle types can be classified and defined, for example, as follows from the viewpoint of traffic control.

That is, a large vehicle has a large degree of occupying a road and a large degree of affecting a traffic flow, and therefore, many roads are subject to traffic regulation. From these viewpoints, large vehicles and ordinary vehicles are first classified. They are further classified into freight cars and passenger cars according to the purpose of the vehicle, that is, a vehicle for transporting luggage or a vehicle for transporting people. After all, they are often classified into four types: heavy trucks, buses, light trucks, and passenger cars.

If the traffic volume and speed are measured for each of the four types of vehicles, a more detailed traffic situation than before can be grasped. In other words, the traffic situation of each vehicle type obtained in this way is sent to the traffic control center and used for wide-ranging control.In addition, the regulation of large vehicles in tunnel traffic etc. is automated, only large vehicles on narrow roads are alternately passed, or There are a wide range of applications to transportation systems that give priority to buses, which are regarded as important public transport systems, and their applications.

Against this background, there are several conventional methods for determining only the vehicle type as follows.

(A) A method of determining the vehicle type by determining the vehicle shape using an ultrasonic pulse radar.

This is done by installing an ultrasonic transducer above the center of the lane (approximately 5m), emitting ultrasonic pulses to vehicles passing below, and measuring the return time of the reflected waves in order to obtain the top shape of the vehicle. This is a method of determining the vehicle.

This method has the disadvantages that the equipment cost is high, and that the propagation speed of the ultrasonic pulse is low, so that a high-speed small car cannot be detected accurately. Also, since an ultrasonic transducer is installed on the road, it is not preferable from the viewpoint of aesthetics.

(B) A method of comparing a change in inductance of a loop coil with a plurality of thresholds to determine a vehicle type.

This embeds the loop coil in the road, the inductance changes as the vehicle passes over the loop coil,
This is a method of comparing the change with a threshold value set in advance for each of a plurality of vehicle types to determine the vehicle type. However, since this method does not necessarily obtain precise vehicle shape data, the determination accuracy is low, and It has the drawback that there are few vehicle types. Further, since the determination is made only depending on the signal level, there is a drawback in that skill is required for use depending on the measurement environment such as the installation state of the loop coil.

On the other hand, conventionally, as a method of measuring the speed, two vehicle sensors are installed at a predetermined distance in the traveling direction of the vehicle, and after the first sensor detects the vehicle, the second sensor detects the vehicle. The method of measuring the speed of the vehicle by calculating from the time until sensing the distance and the distance between the two sensors has been put to practical use,
Since this requires the installation of two sensors, the equipment and construction costs are both expensive, and the sensitivity of the two sensors must be adjusted accurately. In particular, when an ultrasonic vehicle sensor is used, the number of overhead structures increases, which is not preferable in terms of aesthetics.

On the other hand, a so-called Doppler radar measuring device, which transmits a wave to a vehicle traveling by using microwaves or ultrasonic waves and measures the vehicle speed by the Doppler effect of a reflected wave, has been put into practical use. It is expensive, and also has many overhead structures, which is not preferable in terms of aesthetics. Furthermore, since microwaves are used, there are various restrictions on the use of radio waves.

[Problems to be solved by the invention]

The present invention has improved the disadvantages of the above-described conventional apparatus, has an inexpensive configuration, and obtains vehicle shape data to increase the accuracy of vehicle type discrimination. It is an object of the present invention to propose a method and an apparatus for measuring the same.

[Means for solving the problem]

In order to solve the above-described problems, in the present invention, a plurality of time-series characteristics of electric output corresponding to a series of inductance changes that occur each time a traveling vehicle passes through a loop coil disposed on a road surface are stored in advance. The most similar feature is determined by comparing with the time-series feature of each traveling vehicle type, and the vehicle type of the vehicle that has traveled is determined. At the same time, the speed of each vehicle is measured (calculated) using the time during which the inductance of the loop coil changes when the traveling vehicle passes, and the vehicle length data stored in advance for each vehicle type. I do.

In addition, the apparatus of the present invention for this purpose includes a loop coil disposed on a road surface, a conversion unit that sends out an electric output corresponding to the inductance of the loop coil, and when a vehicle travels above the loop coil. A normalizing means for extracting and holding and outputting a time-series characteristic of an output corresponding to a series of inductance changes obtained from the converting means, and a driving vehicle type obtained by the converting means (or equivalent means) for each driving vehicle type Sample storage means for storing in advance typical time-series characteristics of the output as sample data, and the output of the normalization means and the electrical output based on each sample data stored from the sample storage means After the sequential comparison, the most similar sample data is determined, and a vehicle type discrimination unit that sends out a corresponding vehicle type discrimination signal, and an electric power corresponding to the inductance of the loop coil. Timer means for measuring a vehicle passage time in which the force exceeds a predetermined threshold value; storage means for storing vehicle length data corresponding to the sample data for each type of traveling vehicle; and the vehicle length data and the vehicle And a vehicle speed calculating means for calculating the speed of the traveling vehicle from the passing time.

(Operation)

When the traveling vehicle passes above the loop coil, the inductance of the loop coil changes temporally (in chronological order) according to the shape of the vehicle under the floor. This change is converted into an electric signal by the conversion means, and the time-series characteristic is extracted by the normalization means. This characteristic is sequentially compared with the characteristic of the sample data for each vehicle type stored in the sample storage means by the vehicle type determination means, and the sample data which is the closest is determined. The vehicle type discrimination means sends a vehicle type discrimination signal for discriminating and specifying the vehicle type corresponding to the determined sample data to a subsequent device or a transmission line.

In addition, since vehicle length data corresponds to each sample data, the vehicle speed is obtained from the passing time obtained when the vehicle passes over the loop coil and the vehicle length data corresponding to the determined closest sample. The calculation unit can calculate the estimated speed by simple division, and sends the result to a subsequent device or the like.

〔Example〕

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a basic block diagram showing the outline of the apparatus of the present invention. First, the traveling vehicle type determination unit will be described. In the figure, (1) is a loop coil having a predetermined inductance disposed (buried or laid) on a road surface on which a vehicle to be subjected to vehicle type determination runs. Loop coil (1)
According to the condition of the road surface to be provided and various conditions such as the vehicle to be determined, the optimum shape and performance are appropriately selected from various loop coils. (2) is conversion means connected to the loop coil (1), and information (for example, voltage / voltage) corresponding to the inductance of the loop coil (1).
Frequency, etc.). The portions described above are widely used for detecting the presence or absence of a traveling vehicle, counting the number of traveling vehicles, and the like.

FIG. 4 shows a change in inductance of the loop coil (1) when the vehicle actually passes through the vehicle. Fig. 4 shows how the inductance changes when various vehicles pass over a rectangular loop coil with a long side of 2m and a short side of 1m buried on the road surface. The horizontal axis indicates the front edge of the loop coil and the vehicle. The distance from the leading edge (unit: m) is plotted, and the vertical axis represents the rate of change (%) in inductance. As can be seen from the figure, a specific pattern of inductance change occurs for each vehicle type. This is based on the fact that the arrangement including the height of the metal material (mainly iron) that changes the inductance of the loop coil differs for each vehicle type. That is, a vehicle generally uses iron as a material under the floor, and each vehicle has a shape under the floor having substantially the same characteristics. For example, in the case of a passenger car, the floor surface is relatively low, and the floor surface exists at a substantially uniform height. On the other hand, in heavy trucks, the floor position is high, and the axle portion has a metal portion near the road surface. As the vehicle moves in accordance with such underfloor shapes, the magnetic influence on the loop coil on the road surface also changes. Therefore, a temporal pattern change (time-series feature) corresponding to the output (A) of the conversion means (2) is obtained.

The output (A) of the converting means (2) is input to the normalizing means (3) and a speed measuring unit (15) described later. The normalizing means (3) stores the level of the output (A) as time elapses from the start of the change, or divides the time from the start of the change of the output (A) to the end of the change as appropriate, and Time-series characteristics of the input, such as storing as an average value or a peak value of the level (corresponding to a change in the level with the passage of time, a change due to the position of the floor distance in a traveling vehicle, that is, a characteristic of the underfloor shape). Extract
This is retained and stored.

FIG. 5 shows an example of a normalized signal pattern. The change from the start of change of the output (A) to the end of the change (that is, corresponding to the whole time when the vehicle passes) is divided into 10 sections. Are normalized by calculating the average value of. Levels corresponding to these series of sections are stored and held as data in accordance with a certain rule.

In the above-described apparatus, the output level is used as it is, but the output level is normalized by correcting each level by performing an operation so that the average value of the level is constant. This is preferable because normalization and comparison can be performed without being affected by the sensitivity of the entire apparatus.

The signal thus obtained and normalized from the loop coil (1) is input to the vehicle type discriminating means (5). On the other hand, the sample storage means (4) performs the same normalization processing as described above in advance on the output corresponding to each vehicle type to be discriminated, converts the results into data, and sets the data as sample data for comparison to the number of discriminated vehicle types. Store as many as you want. Signals corresponding to these sample data are also input to the vehicle type determining means (5).

The sample storage means (5) has a vehicle length for each vehicle type (accurately,
Effectiveness determined by the length of the loop coil in the traveling direction, the length of the vehicle, and the relative position of the loop coil and the vehicle when the inductance output when the vehicle enters and exits the loop coil exceeds a predetermined threshold. Numerical data (L) corresponding to the vehicle length is stored, and also serves as vehicle length storage means. The vehicle length data (L) is input to a vehicle speed calculation means (18) described later.

The vehicle type discriminating means (5) sequentially compares the normalized signal from the loop coil with a plurality of signals corresponding to each sample data sequentially sent from the sample storing means (4),
Among them, a sample data signal having the most similar characteristics is determined, and an electric signal capable of clearly indicating a vehicle type corresponding to the specific data is transmitted to a subsequent device as a vehicle type determination output. This vehicle type discrimination output is finally tabulated or analyzed and used for traffic control.

Next, the speed measuring unit (15) determines the time during which the output of the conversion means (2) exceeds a predetermined threshold (vehicle transit time:
t) and receives a signal from the vehicle type discriminating means (5), and is stored in advance in the sample storing means (4), which is also a vehicle length storing means, corresponding to the vehicle type determined by the vehicle type discriminating means (5). The vehicle length data (L) is read and the vehicle length data is divided by the vehicle passage time to calculate and measure the speed of the passing vehicle. The obtained speed output is tabulated and analyzed in the same manner as the above-described vehicle type discrimination output, and is used for traffic control. In this embodiment, the sample storage means and the vehicle length storage means are the same, but it goes without saying that they may be provided separately and independently.

Further, the above-mentioned normalizing means (3), sample storing means (4), vehicle type determining means (5), and speed measuring section (15)
Can be easily configured by combining an A / D converter, a microprocessor, a memory, and an I / O circuit.

FIG. 2 is a flowchart showing a schematic flow of the above-described process.

In the method of the present invention, using the apparatus as described above,
A time series characteristic of a series of electric outputs resulting from a traveling vehicle obtained from a loop coil disposed on a road surface was compared with a plurality of time series characteristics of a plurality of pre-stored vehicle types, and the best approximation was made. By determining the vehicle type, the vehicle type of the traveling vehicle to be determined is determined, and the vehicle speed is measured by dividing the vehicle length data corresponding to the vehicle type by the vehicle passage time (t).

FIG. 3 shows the device shown in FIG. 1 in more detail and specifically.

In the figure, the conversion means (2) comprises an oscillation circuit (6), a frequency measurement circuit (7) and a vehicle detection output circuit (8). The oscillation circuit (6) uses a loop coil (1) as an electric element for determining the oscillation frequency.
Therefore, the oscillating frequency of the oscillating circuit (6) depends on the inductance of the loop coil (1). When the inductance changes due to passage of a vehicle or the like, the oscillating frequency also changes.

A frequency measuring circuit (7) subsequent to the oscillating circuit (6) generates a voltage corresponding to the frequency, and a voltage 0 corresponding to the oscillating frequency when the loop coil (1) is in a steady state.
Since the voltage is adjusted to be volts, a voltage is output in accordance with the amount of change in the inductance of the loop coil (1) from the steady state. Note that the electrical constant of the loop coil (1) and the operating state of various circuits gradually change under the influence of environmental changes such as temperature, so that a “drift correction circuit” (not shown) is generally used. Is added to the frequency measurement circuit (7) so that the output in the steady state is maintained at “0”.

The vehicle detection output circuit (8) connected to the output of the frequency measurement circuit (7) (connected in parallel with a timekeeping control circuit (16) described later) has an input higher than a certain voltage (vehicle detection threshold). (Ie, when the vehicle is in the vicinity of the loop coil (1)) and outputs a vehicle detection output.

The normalizing means (3) includes a gate circuit (9), a frequency-voltage conversion circuit (10), an inductance voltage storage circuit (11),
It comprises a normalization pattern creation circuit (12), a clock circuit (13), and a vehicle passage detection circuit (14). The output from the vehicle detection output circuit (8) is applied to a gate circuit (9) and a vehicle passage detection circuit (14). When a vehicle is detected, the aforementioned frequency measurement circuit (7) is passed through a gate circuit (9).
Is applied to an inductance voltage storage circuit (11) via a frequency-voltage conversion circuit (10). At the same time, the vehicle passage detection circuit (14) is a normalized pattern creation circuit (12)
The operation of is started. Inductance voltage storage circuit (1
1) has a function of digitizing an input and sequentially storing and holding it. The clock circuit (13) supplies a sampling pulse necessary for the operation of the inductance voltage storage circuit (11). The normalization pattern creation circuit (12)
The data stored in the inductance voltage storage circuit (11) is sequentially read from the time of detection of the vehicle until the vehicle passes by, and is normalized so as to extract a temporal characteristic of the vehicle that has passed according to a predetermined rule. Here, the predetermined rule is:
For example, a change in the level within a certain period of time from the detection of the vehicle at a certain time interval is obtained, or all data obtained at the time of passing through the vehicle is divided into ten parts in time, and an average value of the level in each part is obtained. Is a processing procedure such as obtaining an array of values of. The data thus normalized is held in the normalized pattern creation circuit (12), and is referred to by the vehicle type discriminating means (5) as necessary. The vehicle type discriminating means (5) sequentially compares the data from the normalization pattern creating circuit (12) with a typical data group for each discrimination target vehicle type stored in advance in the sample storage means (4). Determine the closest data. The vehicle type corresponding to the selected data is output from the vehicle type determining means (5) as the vehicle type that has actually passed. In this output, as in this embodiment,
A dedicated signal line may be provided for each detected vehicle type, or may be coded and transmitted in parallel or serial.

The speed measurement unit (15) is the frequency measurement circuit (7) described above.
And a timekeeping means and a vehicle length storage means, and a vehicle speed calculating means (18), which are constituted by a timekeeping circuit (17) controlled by this output.
The timing control circuit (16) outputs a signal to the timing circuit (17) while the output of the frequency measurement circuit (7), that is, the output corresponding to the inductance of the loop coil (1) exceeds a predetermined threshold. This is a so-called comparator circuit for driving this. The clock circuit (17) includes a counter for counting a clock signal, and this counter is gated by the output of the clock control circuit (16). The count value or time data obtained by converting the count value is transmitted as the vehicle passage time (t). The vehicle speed calculating means inputs vehicle length data (L) from the sample storage means (4), which also serves as vehicle length storage means, in addition to the vehicle passage time (t) from the timing circuit (17). The vehicle speed is calculated based on the two, and a speed output is obtained. The calculation may be started, for example, after completion of both inputs, or the transmission of the output from the clock control circuit (16) or the vehicle type discriminating means (5) may be used.

In addition, the above-described units and units may be integrally formed over the traveling vehicle type determination unit and the speed measurement unit using a system including a microprocessor, a memory, and an I / O unit.

〔The invention's effect〕

As described above, according to the method of the present invention, a plurality of time-series characteristics of the electrical output corresponding to a series of inductance changes that occur each time the traveling vehicle passes through the loop coil disposed on the road surface are stored in advance. For each traveling vehicle type, the vehicle output is compared with the time-series characteristics of the electric output obtained from the loop coil when passing the vehicle, the most similar characteristics are determined, and the vehicle type of the traveling vehicle is determined. Since the speed of the traveling vehicle is calculated using the transit time and vehicle length data stored in advance for each vehicle type, the vehicle type can be determined using the vehicle shape data, and the number of vehicle type classifications , And the vehicle type of a traveling vehicle with high vehicle type determination accuracy can be determined. At the same time, speed information of each passing vehicle is also obtained. Therefore, traffic control and related measures can be performed more finely.

In addition, the apparatus of the present invention for this purpose includes a loop coil disposed on a road surface, a conversion unit that sends out an electric output corresponding to the inductance of the loop coil, and when a vehicle travels above the loop coil. A normalizing unit that extracts and holds and outputs a time-series characteristic of an output corresponding to a series of inductance changes obtained from the conversion unit; and a time-series output of each traveling vehicle type obtained by the conversion unit for each traveling vehicle type. After sequentially comparing the output of the normalizing means and the electrical output based on the characteristic sample stored in the storing means, the sample storage means for storing the features in advance as a feature sample is determined, and the sample data which is most similar is determined. A traveling vehicle type discriminating unit comprising vehicle type discriminating means for transmitting a corresponding vehicle type discriminating signal, and an electric output corresponding to the inductance of the loop coil are predetermined. Timer means for measuring a vehicle transit time exceeding a threshold value, storage means for storing vehicle length data respectively corresponding to the sample data for each traveling vehicle type, and a traveling vehicle based on the vehicle length data and the vehicle transit time. And a speed measuring unit comprising a vehicle speed calculating means for calculating the speed of the vehicle. This is a device that can perform.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing an apparatus of the present invention, FIG. 2 is a flowchart showing an operation process of the present invention, FIG. 3 is a block diagram showing an embodiment of the apparatus of the present invention, FIG. The figure shows an example of an output corresponding to the inductance generated in the loop coil according to the present invention, and FIG. 5 shows an example of a sample pattern in the present invention. (1) Loop coil (2) Conversion means (3) Normalization means (4) Sample storage means (vehicle length storage means) (5) Vehicle type determination means ( 15) Speed measurement unit.

Claims (2)

(57) [Claims] A time series characteristic of an electric output corresponding to a series of inductance changes generated each time a traveling vehicle passes through a loop coil disposed on a road surface is stored in a plurality of time series for each traveling vehicle type. Compared with the characteristic feature, the most similar feature is determined, and the type of the vehicle that has passed and traveled is determined at the same time. A vehicle type discrimination and speed measurement method for measuring the speed of each vehicle using the set vehicle length data. 2. A loop coil disposed on a road surface, conversion means for transmitting an electric output corresponding to the inductance of the loop coil, and a conversion means obtained when the vehicle travels above the loop coil. A normalizing means for extracting and holding and outputting a time-series characteristic of an output corresponding to a series of inductance changes; a sample storing means for pre-storing the time-series characteristic of each traveling vehicle type as sample data; After sequentially comparing the output of the means and the electrical output based on each sample data stored from the sample storage means,
A traveling vehicle type discriminating unit comprising: a vehicle type discriminating unit that determines the most approximated sample data and sends out a corresponding vehicle type discriminating signal;
A time measuring means for measuring a vehicle passage time in which an electric output corresponding to an inductance of a loop coil exceeds a predetermined threshold value; and a vehicle storing vehicle length data corresponding to the sample data for each type of traveling vehicle. Long storage means;
A vehicle type discrimination and speed measurement device including a speed measurement unit including a vehicle speed calculation unit configured to calculate a speed of the traveling vehicle from the vehicle length data and the vehicle passage time.