CN2768106Y - Device for detecting traffic flow speed - Google Patents

Abstract

The utility model provides a device for detecting traffic flow speed, which is characterized in that it is composed of a detection device and a processing system. The detection device is connected with the processing system through a communication device. The detection device includes an LC oscillation circuit and a at least one electromagnetic coil. The utility model is connected with an LC oscillating circuit through an electromagnetic coil, cooperates with a computer to detect the speed of traffic on the road, so the utility model has a simple structure, and is guided by classic electromagnetic theory, the detection result is accurate and reliable, and is suitable for popularization and use.

Description

A device for detecting the speed of traffic flow

                      

The utility model relates to the technical field of traffic flow speed detection, in particular to a method and a device for detecting traffic flow speed by using a coil detector.

Background technique

Traffic data collection is the basic work for traffic planning, design, maintenance and management. Road traffic flow speed detection is an important part of traffic data collection. In traffic control and other fields, it is also very important to detect the speed of traffic flow. Many colleges and enterprises are conducting research on traffic flow speed detection technology.

Among the existing products and documents, the more advanced technology is to use the coil detector to measure the vehicle speed. Most of them need to bury two coils on each lane, and determine the driving speed of the vehicle through the time difference between the two coils when the vehicle passes by. However, there is no vehicle speed detection that can be well completed by using one coil. Using two coils to detect vehicle speed not only wastes coil material, but also consumes a lot of time and energy in road embedding, so it is in urgent need of improvement.

According to the classical electromagnetic theory, it can be known that when a metal object passes through the coil, the inductance of the coil and the frequency of the LC oscillating circuit will also change. Sampling is carried out at a certain sampling frequency, and the frequency deviation value (deviation from the reference value) at the sampling time is plotted, and the frequency change curve generated when the vehicle passes the coil can be obtained. The curve generated when the same vehicle passes the same coil at the same speed is quite stable; different types of motor vehicles have different effects on the coil detector due to different sizes, structures, and materials, so different frequency curves will be produced , especially the peak value has a great degree of discrimination. This is the basis for traffic flow speed detection.

Contents of the invention

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a device which can detect the speed of road traffic flow by using one coil.

The technical scheme that the utility model adopts is as follows:

A device for detecting traffic flow speed is composed of a detection device and a processing system. The detection device is connected with the processing system through a communication device. The detection device includes an LC oscillating circuit and at least one electromagnetic coil connected with the LC oscillating circuit.

In the above technical solution, the device for detecting traffic flow speed detects the frequency deviation value when the vehicle passes the electromagnetic coil through the LC oscillator circuit.

The LC oscillating circuit is composed of inductor L1, capacitors C10, C11, resistors R23, R24, R25, R26, R27, R28 and transistors P5, P6.

The processing system of the utility model adopts an ordinary computer, and the preferred LC oscillation circuit is connected with the computer through the RS232 serial port.

The detection device of the present invention can also include a single-chip microcomputer, the LC oscillating circuit is connected with the single-chip microcomputer, and the single-chip microcomputer is connected with the computer through the RS232 serial port.

The working principle of the utility model is: through the RS232 serial port, the frequency change curve generated by the LC oscillating circuit is transmitted to the computer, and the following method is used to detect the traffic flow speed: firstly, the sample is collected, the waveform library of the traffic flow is established, and then from the waveform The peak characteristic parameter is extracted from the library, which is only related to the size, structure and material of the vehicle, and has nothing to do with the speed. After the feature parameters are extracted, the value range of the parameters can be set in two parallel ways: manual setting or machine learning. Take machine learning as an example: for several collected samples, arrange their peak values according to the rule from small to large. Select a certain range in the wave peak array to represent a model and call it a reference model. For example, 95% to 100% of the waveform value represents a reference model. The passing vehicle can be considered to belong to the reference model. The body length of various reference models generally does not change much. You can manually set the body length of the reference model, add the body length of the reference model to the detection length of the coil, and then divide it by the time interval represented by the waveform generated when the vehicle passes the coil , then the average speed of the reference vehicle on this lane can be obtained. The average speed of the various reference vehicle types obtained above can be used as the average speed of the traffic flow.

The utility model is connected with an LC oscillating circuit through an electromagnetic coil, cooperates with a computer to detect the speed of traffic on the highway, so the utility model has a simple structure, and is guided by classic electromagnetic theory, the detection result is accurate and reliable, and is suitable for popularization and use.

Description of drawings

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the detection flowchart of the utility model;

Fig. 3 is a parameter configuration block diagram of the present utility model;

Fig. 4 is the schematic diagram of the LC oscillating circuit of the present utility model;

Accompanying drawing 5 is the circuit schematic diagram of the single-chip microcomputer of the present utility model.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described.

The structure diagram of the utility model is shown in accompanying drawing 1, and its detection device comprises the electromagnetic coil that is buried under the road surface, the LC oscillation circuit that is connected with electromagnetic coil, and the single-chip microcomputer that is connected with LC oscillation circuit to form, and single-chip microcomputer is connected with RS232 interface again. The computer connection of background processing, present embodiment is also provided with the parameter setting interface circuit that is connected with single-chip microcomputer.

The detection flowchart of the present utility model is as shown in accompanying drawing 2, and the parameter of the electromagnetic frequency offset value that the motor vehicle passing by above is sent to the upper computer by the lower computer, that is, the single-chip microcomputer through the RS232 network interface, namely On the computer, the upper computer filters the received signal so that the signal parameters reach the required range, and then judges the vehicle model corresponding to the signal, and then adds the body length of the judged model to the detection length of the coil, and then divides it by the vehicle The average speed of the reference vehicle on this lane can be obtained from the time interval represented by the waveform generated when passing the coil.

The utility model can set the range of values of the parameters in two parallel ways of manual setting and machine learning, as shown in Figure 3 .

The schematic diagram of the LC oscillating circuit of the present utility model and the circuit schematic diagram of the single-chip microcomputer are shown in accompanying drawing 4, accompanying drawing 5, by inductance L1, electric capacity C10, C11, resistance R23, R24, R25, R26, R27, R28 and triode Composed of P5 and P6, the two ends of the external induction coil are connected to the LOOP1 and LOOP2 ports in the circuit diagram. In the LC oscillating circuit, on the one hand, the self-bias is applied, and the bias is increased during the process of continuous vibration, so that the transistor produces a nonlinear action to limit the collector current. On the other hand, the L and C components are set on the feedback circuit. The resonant circuit makes it tune with the fundamental wave of the output current to generate a sine wave voltage, feeds back part of it, and takes it out as an output at the same time. Due to mutual inductance, when the vehicle passes above the coil detector, the change of the coil oscillation frequency causes the oscillation frequency of the LC oscillation circuit to change accordingly, and the generated sinusoidal signal is output from the triode P6 to the 25th pin of the microcontroller (P2.1).

Claims (6)

1, a kind of device that detects traffic flow speed, it is characterized in that forming by pick-up unit and disposal system, pick-up unit is connected with disposal system by communication facilities, and described pick-up unit comprises LC oscillatory circuit and at least one solenoid that is connected with the LC oscillatory circuit.

2, the device of detection traffic flow speed according to claim 1 is characterized in that the frequency departure value when described device detects vehicle through solenoid by the LC oscillatory circuit.

3, the device of detection traffic flow speed according to claim 1 and 2 is characterized in that described LC oscillatory circuit is made up of inductance L 1, capacitor C 10, C11, resistance R 23, R24, R25, R26, R27, R28 and triode P5, P6.

4, the device of detection traffic flow speed according to claim 3 is characterized in that described disposal system adopts common computer.

5, the device of detection traffic flow speed according to claim 4 is characterized in that described LC oscillatory circuit is connected with computing machine by the RS232 serial ports.

6, the device of detection traffic flow speed according to claim 4 is characterized in that described pick-up unit also comprises single-chip microcomputer, and described LC oscillatory circuit is connected with single-chip microcomputer, and described single-chip microcomputer is connected with computing machine by the RS232 serial ports.

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