JPH0449498A - Method and device for deciding sort of traveling vehicle and measuring speed - Google Patents

Abstract

PURPOSE:To improve the accuracy of deciding the sort of a vehicle and the measuring accuracy of a vehicle speed by comparing a time-sequential feature generated on a loop coil with a time-sequential feature of each traveling vehicle sort to decided the sort of the vehicle and measuring the speed of each vehicle by means of the generation time of an inductance change in the loop coil and vehicle length data. CONSTITUTION:A vehicle sort deciding means 5 successively compares a normalized signal generated from the loop coil 1 with plural signals corresponding to respective sample data successively sent from a sample storing means 4, determines the sample data signal having the most similar feature and sends an electric signal indicating the vehicle sort corresponding to the specific data as a vehicle sort deciding output. A speed measuring part 15 finds out the time in which the output of a conversion means 2 exceeds a previously determined threshold, reads out vehicle length data stored in a sample storing means 4 to be a vehicle length storing means correspondingly to the decided vehicle sort and divides the read value by a vehicle passing time to measure the speed of the passing vehicle. Consequently traveling vehicle decision having high vehicle sort deciding accuracy and speed measurement can be attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a vehicle that is capable of determining the type of vehicle passing on a road and simultaneously measuring its speed, thereby obtaining more detailed information regarding the traffic situation. The present invention relates to a vehicle type identification and speed measurement method and a device therefor.

[Prior art and the problem to be solved by the invention] At the traffic control center, which grasps the traffic volume on the road and contributes to the realization of smooth traffic conditions, the traffic control center automatically receives information sent from vehicle detectors within the control area. Computers analyze and process incoming traffic data and control traffic lights and variable signs according to traffic conditions. General private cars also occupy
Buses, which are considered important as mass public transportation, are also included. In order to understand the traffic conditions for each type of vehicle, a large amount of manpower and many days are required to conduct a survey in advance, and the results are currently used as fixed parameters for traffic control.

In addition, the results of measuring vehicle speeds, which are performed unrelated to vehicle type identification, are also used for appropriate control of traffic signals, etc.

By the way, if it were possible to send traffic conditions by vehicle type to a traffic control center from time to time, along with speed information for each vehicle, traffic events such as congestion could be known quickly, and more detailed traffic control such as corresponding control could be implemented. Control becomes possible. In fact, no matter where you look at the roads, there are many different types of vehicles driving on them, and their speeds also vary.
Merely measuring traffic volume alone is considered insufficient to accurately understand traffic conditions.

Therefore, it is important to determine the type of vehicle, ie, "vehicle type," and to count each vehicle type, as well as to measure the speed of each vehicle. Note that from the viewpoint of traffic control, vehicle types can be classified and defined as follows, for example.

That is, large vehicles occupy roads to a large extent and have a large influence on traffic flow, and therefore many roads are subject to traffic regulations. From this point of view, vehicles are classified into large vehicles and ordinary vehicles. Furthermore, vehicles are classified into freight vehicles and passenger vehicles depending on their purpose, ie, whether they are used to transport cargo or people. In the end, they are often classified into a total of four types: large l/racks, buses, small trucks, and passenger cars.

By measuring the traffic volume and speed for each of the four types of vehicles classified above, it will be possible to understand the traffic situation in a more detailed manner than ever before. In other words, the traffic conditions obtained by vehicle type are sent to the traffic control center and are used for wide-ranging control, as well as automation of regulation of large vehicles in tunnel traffic, alternating passage of only large vehicles on narrow roads, etc. The scope of its application is wide-ranging and can be applied to transportation systems that give priority to buses, which are considered important as mass public transportation.

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

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

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

This method has the disadvantage that in addition to high equipment costs, the propagation speed of the ultrasonic pulse is slow, making it impossible to accurately detect high-speed small vehicles. Furthermore, since the ultrasonic transducer is installed on the road, it is not aesthetically pleasing.

(b) A method of determining the vehicle type by comparing changes in the inductance of the loop coil with multiple threshold values.

In this method, a loop coil is buried in the road, and when a vehicle passes over the loop coil, the inductance changes, and the vehicle type is determined by comparing this change with a preset threshold for each vehicle type. However, this method has the disadvantage that accurate vehicle shape data is not obtained, so the discrimination accuracy is low, and there are only a few classification types of vehicle types. Another drawback is that since the determination depends only on the signal level, it is affected by the measurement environment such as the installation state of the loop coil and requires skill to use.

On the other hand, the conventional method for measuring speed is to install two vehicle detectors a certain distance apart in the direction of travel of the vehicle, and
Calculated from the time from when one sensor detects the vehicle until the second sensor detects the vehicle and the distance between the two sensors,
A method of measuring the speed of a vehicle has been put into practical use, but this requires the installation of two sensors, so it is difficult to use a device.
- The cost is high, and it is necessary to accurately adjust the sensitivity of the two sensors. In particular, when an ultrasonic vehicle sensor is used, there are many overhead structures, which is not aesthetically pleasing.

On the other hand, measurement devices using so-called Doppler radars, which use microwaves and ultrasonic waves to transmit waves toward a moving vehicle and measure the vehicle speed by the Doppler effect of the reflected waves, have also been put into practical use. However, it is expensive and requires a lot of structures above the head, which is not aesthetically pleasing. Furthermore, since microwaves are used, there are various restrictions on the use of radio waves.

[Problem to be solved by the invention]

The present invention improves the drawbacks of the conventional devices described above, has an inexpensive configuration, and obtains vehicle shape data to improve the accuracy of vehicle type discrimination. Our goal is to propose a method and device that can measure the same.

[Means to solve the problem]

In order to solve the above problems, the present invention stores time-series characteristics of electrical output corresponding to a series of inductance changes that occur each time a vehicle passes in a loop coil disposed on the road surface. The time-series characteristics of each type of vehicle are compared with those set, the most similar characteristics are determined, and the type of vehicle that has passed is determined based on the most similar characteristics. At the same time, the speed of each vehicle is measured (calculated) using the time during which an inductance change occurs in the loop coil when a vehicle passes by, and vehicle length data stored in advance for each vehicle type.
I'll do what I do.

Further, the device of the present invention for this purpose includes a loop coil disposed on the road surface, a conversion means for sending out an electric output corresponding to the inductance of the loop coil, and a converting means for transmitting an electric output corresponding to the inductance of the loop coil. normalization means for extracting and retaining time-series characteristics of the output corresponding to a series of inductance changes obtained from the conversion means; sample storage means for storing in advance typical time-series characteristics of the output as sample data; and an electrical output based on the output of the normalization means and each sample data stored from the sample storage means. After sequential comparison, a vehicle type discrimination unit determines the most similar sample data and sends out a corresponding vehicle type discrimination signal, as well as a vehicle passing unit whose electrical output corresponding to the inductance of the loop coil exceeds a predetermined threshold. A clock means for measuring time, a storage means for storing vehicle length data corresponding to the sample data for each vehicle type, and a vehicle speed calculation means for calculating the speed of the traveling vehicle from the vehicle length data and the vehicle passing time. A speed measuring section comprising:

[For production]

When a traveling vehicle passes above the loop coil, the inductance of the loop coil changes over time (time series) in accordance with the underfloor shape of the vehicle. This change is converted into an electrical signal by the conversion means, and its time-series characteristics are extracted by the normalization means. These characteristics are sequentially compared with the characteristics of the sample data for each vehicle type stored in the sample storage means by the vehicle type discriminating means, and the most similar sample data is determined. The vehicle type discriminating means transmits a vehicle type discriminating signal that clearly identifies the vehicle type corresponding to the determined sample data to a subsequent device or transmission line.

In addition, since vehicle length data corresponds to each sample data, the vehicle speed can be determined 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 means 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 schematically showing the apparatus of the present invention. First, the traveling vehicle type determination section will be explained. In the figure, (1) is a loop coil having a predetermined inductance that is disposed (buried or laid) on the road surface on which a vehicle to be discriminated by vehicle type runs. The loop coil (1) is appropriately selected from among various types of loop coils, depending on various conditions such as the condition of the road surface on which it is disposed and the vehicle to be discriminated. (2) is a conversion means connected to this loop coil (1);
This is a known circuit that outputs electrical output including information (for example, voltage, frequency, etc.) according to the inductance of the inductance. The parts described above are widely used for detecting the presence or absence of running vehicles, counting the number of running vehicles, etc.

Here, FIG. 4 shows changes in the inductance of the loop coil (1) when a vehicle actually passes through the vehicle. Figure 4 shows how inductance changes when various vehicles pass over a rectangular loop coil with a long side of 2 m and a short side of 1 m buried in the road surface. The distance from the front edge of the vehicle is expressed in meters (m), and the rate of change in inductance (%) is plotted on the vertical axis. As can be seen from the figure, a unique pattern of inductance changes 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 depending on the vehicle model.

That is, vehicles generally use iron as a material for the underfloor portion, and each vehicle type has an underfloor shape with substantially similar 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, large trucks have high floors and metal parts on their axles close to the road surface. According to each underfloor shape, the magnetic influence of the road surface on the loop coil changes as the vehicle moves. Therefore, a temporal pattern change (time-series feature) corresponding to the output (A) of the converting means (2) is obtained.

The output (A) of the conversion means (2) is converted into a normalization means (3).
and is input to a speed measuring section (15) which will be described later.

The normalizing means (3) stores the level of the output (A) according to the passage of time from the start of the change, or stores the level of the output (A)
The time-series characteristics of the input (how the level changes over time, the running vehicle (corresponding to the characteristics of the under-floor shape) is extracted and retained and stored.

Figure 5 shows an example of a normalized signal pattern, in which the change in output (A) from the start of the change to the end of the change (corresponding to the entire time when the vehicle passes) is divided into 10 sections. It is normalized by finding the average value of . The levels corresponding to each of these series of intervals are stored and held as data according to a certain rule.

Note that the above method uses the output level as it is, but it stores and stores the normalized value by performing calculations and correcting each level so that the average value of the level for the entire interval is constant. This is preferable because normalization and comparison can be performed without being affected by the sensitivity of the entire device.

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

Incidentally, the sample storage means (5) stores the vehicle length for each vehicle type (specifically, the length of the loop coil in the traveling direction, the length of the vehicle, and Numerical data (L) corresponding to the effective vehicle length determined by the relative position of the loop coil and the vehicle at the time when the inductance output exceeds a predetermined threshold when the vehicle enters and exits the loop coil is stored. It also serves as vehicle length storage means. This vehicle length data (L) is input to vehicle speed calculation means (18), which will be described later.

The vehicle type discrimination means (5) sequentially compares the normalized signal from the loop coil with a plurality of signals corresponding to each sample data sequentially sent out from the sample storage means (4), and selects the most among them. A sample data signal having similar characteristics is determined, and an electrical signal capable of specifying the vehicle type corresponding to this specific data is sent to a subsequent device as a vehicle type discrimination output. This vehicle type identification output will ultimately be aggregated, analyzed, and used for traffic control.

Next, the speed measuring unit (15) measures the time during which the output of the converting means (2) exceeds a predetermined threshold (vehicle passing time:
t), and in response to a signal from the vehicle type discriminating means (5), the vehicle type discriminating means (5) stores in advance in the sample storage means (4), which is also a vehicle length storage means, corresponding to the determined vehicle type. The speed of the passing vehicle is calculated and measured by reading out the vehicle length data (transformed into vehicle length data) and dividing this vehicle length data by the vehicle passing time. The obtained speed output is aggregated, analyzed, and used for traffic control in the same way as the vehicle type discrimination output described above. 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.

In addition, the above-mentioned normalization means (3) and sample storage means (4)
, the vehicle type discrimination means (5) and the speed measurement section (15) are A
/D converter and microprocessor, memory and I
It can be easily configured by combining 10 circuits.

FIG. 2 shows a flowchart showing the general flow of the process described above.

In the method of the present invention, the above-described device is used to memorize and store the time-series characteristics of a series of electrical outputs caused by a running vehicle obtained from a loop coil disposed on the road surface, and a plurality of children. The vehicle type of the target vehicle is determined by comparing multiple time-series characteristics for each vehicle type and determining the most similar one, and the vehicle length data corresponding to this vehicle type is calculated using the vehicle passing time (1). Measure the vehicle speed by dividing by

FIG. 3 specifically illustrates the apparatus shown in FIG. 1 in more detail.

In the figure, the converting means (2) consists of an oscillation circuit (6), a frequency measuring circuit (7), and a vehicle detection output circuit (8). The oscillation circuit (6) uses a loop coil (1) as an electrical element that determines its oscillation frequency. Therefore, the oscillation frequency of the oscillation circuit (6) is
It depends on the inductance (1), and if the inductance changes due to passing of a vehicle, etc., the oscillation frequency will also change.

The frequency measurement circuit (7) following the oscillation circuit (6) generates a voltage corresponding to the frequency, and is connected to the loop coil (1).
) is adjusted so that the voltage becomes O volts corresponding to the oscillation frequency in a steady state, so the loop coil (1)
A voltage is output according to the change in inductance from the steady state.

Note that the electrical constants of the loop coil (1) and the operating states of various circuits fluctuate slowly due to changes in the surrounding environment such as temperature, so generally a "drift correction circuit" is used.
(not shown) is added to the frequency measuring circuit (7) to maintain the output at "0#" in a steady state.

A vehicle detection output circuit (8) connected to the output of the frequency measurement circuit (7) (connected in parallel with a timing control circuit (16) described later) has an input voltage equal to or higher than a certain voltage (vehicle detection threshold). (ie, when the vehicle is near the loop coil (1)) and outputs a vehicle detection output.

The normalization means (3) includes a gate circuit (9), a frequency-voltage conversion circuit (10), and an inductance voltage storage circuit (11).
, normalization pattern creation circuit (I2), clock circuit (1
3) 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 output from the frequency measurement circuit (7) described above is sent to the frequency-voltage conversion circuit (
10) to the inductance voltage storage circuit (1). At the same time, the vehicle passage detection circuit (14) starts the operation of the normalization pattern creation circuit (12). The inductance voltage storage circuit (moon) has the function of digitizing input and sequentially storing it. The clock circuit (J3) is this inductance voltage storage circuit (j])
Supplies sampling pulses necessary for operation. The normalization pattern creation circuit (12) stores the inductance voltage storage circuit (11) from the time of vehicle detection until the vehicle passes by.
The stored data is sequentially read out and normalized to extract temporal features related to passing vehicles according to predetermined rules.

Here, the predetermined rule refers to, for example, finding changes in the level at certain time intervals within a certain time from the time of vehicle detection, or dividing all data obtained when a vehicle passes into 10 temporally and dividing it into 10 sections. This refers to processing procedures such as finding the average value of the levels and finding an array of 10 values. The data thus normalized is held in the normalization pattern creation circuit (12) and is referred to by the vehicle type discrimination means (5) as needed. The vehicle type discrimination means (5) sequentially compares the data from the normalization pattern generation circuit (12) with a typical data group for each vehicle type to be discriminated, which is stored in advance in the sample storage means (4), and determines the characteristics. Determine the most similar data.

The vehicle type corresponding to the selected data is outputted from the vehicle type discriminating means (5) as the vehicle type that actually passed.

For this output, a dedicated signal line may be provided for each detected vehicle type as in this embodiment, or it may be encoded and transmitted in parallel or serially.

The speed measurement unit (15) is the frequency measurement circuit (7) described above.
It consists of a time control circuit (16) connected to the output of the time control circuit (16), a time control circuit (17) controlled by this output, a time measurement means, a vehicle length storage means, and a vehicle speed calculation means (18). The time control circuit (16) outputs a signal to the time measurement 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 what drives this,
This is a so-called comparator circuit. The timekeeping circuit (17) includes a counter that receives a clock signal one by one, and this counter is gated by the output of the timekeeping control circuit (6), and waits for the end of the count to operate the vehicle speed calculation means. (18), convert the count value or the time data obtained by converting it into the vehicle passing time (
i). In addition to the vehicle passing time (1) from the timing circuit (17), the vehicle length data (converted into vehicle length data) from the sample storage means (4), which also serves as vehicle length storage means, is input to this vehicle speed calculation means. Based on both, the vehicle speed is calculated and a speed output is obtained. Note that the calculation may be started after, for example, both human resources are available, or the calculation may be started by sending an output from the timing control circuit (16) or the vehicle type discriminating means (5).

In addition, each part and each means mentioned above is a microprocessor,
It is also possible to use a system including 110 parts of memory to seamlessly and integrally straddle the vehicle type determination part and the speed measurement part.

〔Effect of the invention〕

As described above, according to the method of the present invention, the time-series characteristics of the electrical output corresponding to a series of inductance changes that occur in a loop coil disposed on the road surface as a vehicle passes through the road are stored in a plurality of children. The time-series characteristics of the electrical output obtained from the loop coil when the vehicle passes are compared with the time-series characteristics of the electric output obtained from the loop coil for each type of vehicle that has been set, and the most similar characteristics are determined. Since the speed of the traveling vehicle is calculated using the passing time and vehicle length data stored in advance for each vehicle type7, the vehicle type can be determined using the vehicle shape data, and the vehicle type classification. It is possible to identify the vehicle type of a large number of running vehicles with high vehicle type discrimination accuracy. At the same time, speed information of each passing vehicle is also obtained.

Therefore, it becomes possible to carry out more detailed traffic control and related measures.

Further, the device of the present invention for this purpose includes a loop coil disposed on the road surface, a conversion means for sending out an electric output corresponding to the inductance of the loop coil, and a device for driving the loop coil when the vehicle passes through one of the loop coils. i from the conversion means to
a normalizing means for extracting, retaining, and outputting time-series characteristics of an output corresponding to a series of inductance changes, and a time-series characteristic of an output for each type of vehicle during driving obtained by the conversion means for each type of vehicle; After sequentially comparing the output of the sample storage means, which is stored in advance as a sample, and the electrical output based on the characteristic sample stored in this storage means, the most approximate sample data is determined, and the corresponding sample data is determined. A traveling vehicle type discriminating unit comprising a vehicle type discriminating means which transmits a vehicle type discriminating signal S1, and an electric output corresponding to the inductance of the loop coil which measures the vehicle passing time exceeding a predetermined threshold value. a storage means for storing vehicle length data corresponding to the sample data for each type of vehicle; and a vehicle speed calculation means for calculating the speed of the vehicle from the vehicle length data and the vehicle passing time. Since it is composed of a simple and therefore inexpensive structure, it is possible to classify a large number of vehicle types, and it becomes an apparatus that can perform running vehicle discrimination and speed measurement with high vehicle type discrimination accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an outline of the device of the present invention, FIG. 2 is a flowchart 1 showing the operation process of the present invention, and FIG. 3 is a block diagram showing an embodiment of the device of the present invention. , FIG. 4 is a diagram showing an example of the output corresponding to the inductance generated in the loop coil according to the present invention, and FIG. 5 is a diagram showing an example of the 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 discrimination means, (15)...Speed measurement section.

Claims (1)

[Scope of Claims] [1] A driving system in which time-series characteristics of electrical output corresponding to a series of inductance changes that occur each time a traveling vehicle passes are stored in a loop coil disposed on the road surface in a plurality of children. It compares the time-series characteristics of each vehicle type, determines the most similar characteristics, and uses this to determine the type of vehicle that has passed.
A method for determining the vehicle type and measuring the speed of a traveling vehicle, which measures the speed of each vehicle using the time during which an inductance change occurs in a loop coil when the vehicle passes by, and vehicle length data stored in advance for each vehicle type. . [2] A loop coil disposed on the road surface, a conversion means for sending out an electrical output corresponding to the inductance of the loop coil, and a series of electric outputs obtained from the conversion means when a vehicle passes above the loop coil. normalizing means for extracting, retaining and outputting time-series characteristics of output corresponding to inductance changes; sample storage means for storing time-series characteristics for each vehicle type as sample data in advance; a vehicle type discriminating means that sequentially compares the output with the electrical output based on each sample data stored from the sample storage means, determines the most similar sample data, and sends out a corresponding vehicle type discriminating signal. a vehicle type discrimination section, a timer for measuring the vehicle passing time during which the electrical output corresponding to the inductance of the loop coil exceeds a predetermined threshold, and vehicle length data each corresponding to the sample data for each traveling vehicle type. A vehicle type determination and speed measuring device for a running vehicle, comprising a speed measuring section comprising a vehicle length storage means for storing the vehicle length data and a vehicle speed calculation means for calculating the speed of the running vehicle from the vehicle length data and the vehicle passing time.