JPS5880938A - Vehicle communication system - Google Patents

Abstract

PURPOSE:To reduce the installation cost of a device by using a loop coil which is buried under a road surface to sense a vehicle even for vehicle communication, and simultaneously performing communication operation between a ground equipment and a vehicle-mounting equipment and vehicle sensing operation at different frequencies. CONSTITUTION:The oscillating circuit 10 of a ground equipment applies a signal of frequency f1 to a tuning circuit 12 and a phase comparator PD13, which makes a phase comparison between outputs of the circuits 10 and 12. Before a vehicle enters into a loop coil 2, the outputs of the circuits 10 and 12 are in phase with each other and the output of the PD13 is 0. Once the vehicle enters into the coil 2, the signal applied to the PD13 shifts in phase and the PD13 outputs a signal to a level detecting circuit 14, which when detecting a level higher than a specified value, outputs a vehicle sense signal (d) through a holding circuit 17. For communication between the ground equipment and a vehicle-mounting equipment, the ground equipment modulates a carrier of frequency f2 by a signal (g) to transmit the resulting signal through BPFs 27 and 18, and receives a signal of frequency f3 from the vehicle-mounting equipment through a BPF20. The vehicle-mounting equipment receives the signals of f1 and f2 through an antenna and the BPF and transmits the signal f3 through the BPF.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle-to-vehicle communication system performed between a ground machine and an on-vehicle machine of a traveling vehicle.

Conventionally, in vehicle-to-vehicle communication using guided radio, a loop coil buried in the road surface is connected to a ground machine at each communication point, and the loop coil is used as a transmitting/receiving antenna. On the other hand, a loop-type vehicle sensor for detecting a vehicle may be separately provided at the communication point. A loop-type vehicle sensor continuously oscillates an oscillator that includes a loop coil.
Vehicle sensing is performed by detecting inductance changes that occur when a vehicle passes over the loop coil.

In this way, conventionally, a loop coil for vehicle-to-vehicle communication and a loop coil for vehicle sensing were provided separately, and vehicle-to-vehicle communication and vehicle sensing were performed independently. This was extremely uneconomical from the perspective of the entire anti-vehicle system.
Equipment installation costs are low and facilities.

An object of the present invention is to provide a vehicle-to-vehicle communication system that is easy to maintain and repair.

In order to achieve the above object, in the vehicle-to-vehicle communication system of the present invention, a loop coil buried in the road surface for vehicle sensing is also used for vehicle-to-vehicle communication. That is, the vehicle-to-vehicle communication system of the present invention includes an oscillation circuit connected to a loop coil buried in the road surface that oscillates at a first frequency in a ground plane, and a frequency of the oscillation circuit that is connected to this oscillation circuit and changes when a vehicle arrives. a vehicle sensing circuit that detects a vehicle by detecting a vehicle; and a transmitting/receiving circuit that is connected to the loop coil and performs vehicle-to-vehicle communication with the vehicle via the loop coil using a signal of a second frequency different from the first frequency. Equipped with a section.

The vehicle includes an antenna and an on-vehicle device that is connected to the antenna and includes a transmitting/receiving circuit unit that communicates with the ground device.

The communication operation between the ground plane and the vehicle-mounted machine is performed simultaneously with the vehicle sensing operation by the vehicle sensing circuit at different frequencies.

The present invention will be described in detail below with reference to an embodiment shown in the drawings. Fig. 1 is a schematic diagram of an apparatus in which the invention is implemented. In the figure, a loop coil 2 is buried in the road surface 1.
This loop coil 2 is connected to a ground plane 4 provided on the roadside 5. The traveling vehicle 5 is also provided with an antenna 6 and an on-vehicle device 7 connected to the antenna 6. When the traveling vehicle 5 passes over the loop coil 2, the loop coil 2
The vehicle is sensed by the vehicle sensing circuit in the ground plane 4, and the loop coil 2. Vehicle-to-vehicle communication is performed via the antenna 6. FIG. 2 is a block diagram showing the circuit configuration of the ground plane 4. As shown in FIG.

The oscillation circuit 10 is connected to a loop coil 2 outside the ground plane via a bandpass filter circuit 11. The oscillator circuit 10 performs self-excited oscillation at a frequency f1 using the built-in valley C and the inductance of the loop coil.The 0-band filter circuit 11 is 1
The oscillation circuit 10 has a pass band that is the maximum frequency shift width of the oscillation circuit 10, and is a circuit that prevents a signal for vehicle communication, which will be described later, from entering the vehicle sensing circuit side. and directly connected to the phase comparator circuit 13. The resonance frequency of the tuned circuit 12 is selected to be the oscillation frequency of the oscillation circuit 10 when no vehicle is approaching. Therefore, normally the signal from the tuning circuit 12 applied to the phase comparison circuit 15 and the signal from the oscillation circuit 10 are in phase, but when a vehicle approaches the loop coil 2, the oscillation frequency of the oscillation circuit 10 changes. The output terminal of the 0-phase comparison circuit 13 to which two signals with different phases are input is connected to the level detection circuit 14 and also connected to the integrating circuit 16 via the switch 15. The 0 level detection circuit 14, which outputs a voltage proportional to the phase difference of the signals, derives an output signal when the voltage from the phase comparison circuit 13 is above a certain level.

The integrator circuit 16 is a circuit with a large time constant, and when the inductance of the loop coil 2 changes due to a change in temperature, for example, the output of the phase comparator circuit 13 due to the change is fed back to the tuning circuit 12 to prevent resonance of the tuning circuit 12. The frequency is controlled so as to follow the oscillation frequency, so that the oscillation frequency of one oscillation circuit 10 and the resonance frequency of the tuning circuit 12 match. However, in the case of a sudden change such as when a vehicle approaches, the integration circuit 16 does not follow it, so no correction is made, and the phase comparator circuit 13 outputs a constant output, so the level detection circuit 14 detects the output signal. Derive. The output terminal of the level detection circuit 14 is connected to the holding circuit 17. The holding circuit 17 receives the signal from the level detection circuit 14, holds it for a certain period of time, and outputs a vehicle sensing signal. While the output is being delivered to the holding circuit 17, the switch 1
5 is turned off.

μm pukoi/L/2 is a bandpass filter circuit 18. Dual transmitter/receiver 19. It is connected to an amplifier circuit 21 via a bandpass filter circuit 20. The bandpass filter circuit 18 is configured to pass signals for communication with the vehicle and have an infinite impedance so as not to be affected by the signal of frequency f1 from the 9 oscillation circuit 10. The band filter circuit 20 is a circuit for removing noise, and the amplifier circuit 21 is a circuit for amplifying the signal (center frequency f3) from the on-vehicle device 7.

The amplifier circuit 21 is connected to a detection circuit 22 and a demodulation circuit 23. The detection circuit 22 is a circuit for detecting a signal from the on-vehicle device 7, and the demodulation circuit 23 is a circuit for extracting vehicle data from the signal from the on-vehicle device 7. The detection circuit 22 and the demodulation circuit 23 are connected to a transmission control circuit 24. The transmission control 1 circuit 24 executes control operations according to the flowchart of FIG. 6, which will be described later. The transmission control circuit 24 is connected to add information data to the modulation circuit 25 in order to send information data from the ground plane 4 to the P vehicle/warplane 7. The modulation circuit 25 is a circuit for modulating the carrier wave f2 with transmission information. The modulation circuit 25 is connected to an amplifier circuit 26, and the amplifier circuit 26 is connected to a bandpass filter circuit 27.
It is connected to the transmitter/receiver unit 19 via the transmitter/receiver.

FIG. 3 is a block diagram showing the circuit configuration of the vehicle-mounted device 7. As shown in FIG.

The antenna 6 is connected to bandpass filter circuits 52 and 55 via a transmitting/receiving device 31.

The bandpass filter circuit 32 is a circuit for passing a signal (frequency r1) from the oscillation circuit 1 of the ground plane 4, and the bandpass filter 63 passes a signal (center frequency f2) from the modulation circuit 25 of the ground plane 4. ) is a circuit for passing. The bandpass filter circuit 32 is connected to a transmission control circuit 65 via a detection circuit 34. Bandpass filter circuit 66 is connected to amplifier circuit 36 . The amplifier circuit 66 is a circuit for amplifying the signal from the modulation circuit 25 of the ground plane 4 that is caught by the antenna 6. The output end of the amplifier circuit 36 is connected to a detection circuit 57 and a demodulation circuit 38, respectively. Detection circuit 37. The output end of the demodulation circuit '5 is the transmission control circuit 6.
5, respectively. The detection circuit 37 is the ground plane 7
The demodulation circuit 38, which is a circuit for detecting a different anti-vehicle signal and obtaining a pulse signal corresponding to the anti-vehicle signal, is a circuit for extracting information data from the modulated signal containing information data from the ground plane 7. . The transmission control circuit 35 is connected to send vehicle data to the ground plane 4 and to add vehicle data to the modulation circuit 39 . The modulation circuit 39 transmits a carrier wave (
This is a circuit for modulating the frequency f3) with sending vehicle data, and its output end is connected to the amplifier circuit 40. The amplifier circuit 40 is a circuit for amplifying the modulated signal,
Its output end is connected to a transmitting/receiving device 51 via a bandpass filter circuit 41.

Next, a description will be given of the operation when vehicle sensing and vehicle-to-vehicle communication are performed using the ground machine and on-vehicle machine configured as described above. In the following operation description, the time chart of each circuit part of the ground plane shown in FIG. 4 will be used.

6 is a time chart of each part of the circuit of the on-vehicle device shown in FIG. 5.

This will be explained with reference to a control flowchart of the transmission control circuit of the ground plane shown in FIG. 6 and a control flowchart of the transmission control circuit of the vehicle-mounted machine shown in FIG.

When the ground plane 4 starts operating, the oscillation circuit 10 starts oscillating and generates a signal with a frequency f1 shown in FIG. 4a. This signal a
is applied directly to the phase comparison circuit 13, and the signal after passing through the tuning circuit 12 is also applied to the phase comparison circuit 13.

If the vehicle has not entered the loop coil 2, these signals are in phase, so the output of the phase comparison circuit 13 is D. Furthermore, when the vehicle approaches μm pukoi) v2, the phase of both signals applied to the phase comparator circuit 13 will be slightly shifted due to this influence, and the output signal of the phase comparator circuit 13 will have some output voltage as shown in Fig. 4. Derive. However, in this case, since the level of the signal S is still below a certain level, the output signal C of the level detection circuit 14 remains at a low level. However, when the vehicle 5 completely enters the loop coil (loop coil) v2, the inductance of the coil changes significantly, so the phase difference between the two signals applied to the input of the phase comparison circuit 13 becomes large, and the phase comparison circuit 1'5 of the first phase comparison circuit 1'5 becomes large. The output signal becomes a signal above a certain level.

Therefore, the level detection circuit 14 derives the signal of shown in FIG. This signal C is further applied to the holding circuit 17 and held for a certain period of time. The output signal d of this holding circuit 17 is a vehicle sensing signal. By outputting this vehicle detection signal, the ground plane 4 can detect a vehicle, that is, know the arrival of a vehicle.

On the other hand, when a vehicle approaches loop coil 2.

The antenna 6 has a bandpass filter circuit 11 than an oscillation circuit 10.
．． /L'-Catch the signal being sent through the coil 2. The caught signal of frequency 11 is sent to the transmitting/receiving device 51. However, since the bandpass filters 32 and 35 have different passband characteristics, the lever signal is derived only to the output side of the bandpass filter 32. The signal on the output side of the bandpass filter circuit 32 is as shown in FIG. 5. This signal q is applied to a detection circuit 34 and detected to obtain a detected signal r shown in FIG.

This detected signal r is applied to the transmission control circuit 35.

As shown in FIG. 7, the transmission control circuit 35 makes a 9-decision in step 70 as to whether a loop sensing signal has been detected, and if the detection signal r is not derived at a high level, the determination is NO and the process proceeds to step 71 to turn off the modulation operation. Then, the process returns to step 70, but when the detection signal r is added as described above, the determination is Y.
With ES, the process moves to step 72. and in step 72 the fifth
The signal shown in FIG. The modulation circuit 39 receives vehicle data m
The modulated wave k (center station, wave number r5) modulated by the amplifier circuit 40 is output, and this signal is amplified by the amplifier circuit 40, and then passed to the bandpass filter circuit 41. The signal is transmitted to the outside of the vehicle from the t-antenna 6 via the transmitting/receiving device 31.

The modulated wave sent out from the on-vehicle device 7 is caught by the loop coil 2 and applied to the bandpass filter circuit 11°18, but the frequency band of the modulated wave is
Since this signal is different from the 0 passband, this signal is passed through the bandpass filter 18.
Only pass through. And a transmitting/receiving device 19. The signal is applied to the amplifier circuit 21 via the bandpass filter circuit 20 and amplified, and the signal shown in FIG. 4 is obtained at the output terminal of the amplifier circuit 21. This signal is detected by the detection circuit 22, and a detected signal j shown in FIG. 4 is obtained. At the same time, the output signal of the amplifier circuit 21 is also applied to the demodulation circuit 23, so that the vehicle data as the demodulation signal shown in FIG. 4 is derived at the output side of the demodulation circuit 23.

In the transmission control circuit 24, as shown in the flowchart of FIG. 6, it is determined in step 60 whether there is a detected signal (if there is no detected signal, the modulation operation is turned off in step 61), and in step 62 it is determined whether a start signal has been received. However, since the detection signal is added by the detection circuit 22, the vehicle data signal is added by the demodulation circuit 23, and the start signal in the vehicle data signal is also confirmed, the determinations at steps 60 and 62 are both YES. The operation of the transmission control circuit 23 moves to step 63. In step 66, the added vehicle data is read. This data reading operation continues until the stop signal attached to the end of the vehicle data is input. When the stop signal is received, the determination in step 64 as to whether the stop signal has been received becomes YES, and step 6
Moving on to step 5, vehicle data is analyzed. and step 6
In step 6, information corresponding to the analyzed vehicle data is created.

Next, in step 67, the signal shown in FIG.
In addition to step 5, the modulation operation is turned on, and in step 68, the information data shown in FIG. 4g is added to the modulation circuit 25. The modulation circuit 25 modulates the carrier wave (center frequency "2") with the signal g and outputs the modulated wave e shown in FIG.
is amplified by the amplifier circuit 26 and passed through the bandpass filter circuit 27 . The signal is sent out from the loop coil 2 via the transmitting/receiving device 19 and the bandpass filter circuit 18.

The modulated wave e sent out from the loop coil 2 is caught by the antenna 6 of the vehicle 5, passed through the transmitting/receiving device 31 and the f-band filter circuit 33, and then added to the amplifier circuit 66 where it is amplified. At the output terminal of the amplifier circuit 36, a signal shown in FIG. 5n is obtained.

This signal n is detected by the detection circuit 67, and the detected signal 1d signal p shown in FIG.
In other words, the information data from the first heir on the ground is demodulated and connected 58
is led out to the output terminal of. Then, these detected signal p and demodulated signal 0 are applied to the transmission control circuit 35.

The transmission control circuit 35 determines whether there is a received detection signal (detection circuit 37) in step 74 of the flowchart of FIG. Therefore, the operation of the transmission control circuit 35 moves to step 75, where it is determined whether the start signal has been received. Information data 0 from demodulation circuit 38
When , the start signal included in the information data 0 is received, so the determination at step 75 is also YES.

Go to step 76. In step 76, information data from the ground plane 4 is read. The process of step 76 is continued until the stop signal attached to the end of the transmission data is received. When the transmission control circuit 35 receives the stop signal, it determines whether the stop signal has been received in step 77 as Yjl! ; becomes S.

Proceeding to step 78, information from the ground plane is output to a display in the vehicle.

In the above embodiment, the oscillation frequency f1 of the oscillation circuit for vehicle sensing, and the frequency f2 of the signal for vehicle communication. Since f3 is a different frequency, the vehicle sensing signal may affect vehicle-to-vehicle communication.

Conversely, signals for vehicle-to-vehicle communication do not disturb the vehicle sensing operation.

As described above, according to the vehicle-to-vehicle communication system of the present invention, the oscillation frequency of the oscillation circuit for vehicle sensing and the signal frequency for vehicle-to-vehicle communication are selected to be different frequencies.

Since the loop coil for vehicle sensing and the loop coil as an antenna for vehicle-to-vehicle communication are used together, the ground plane Only one loop coil is required to be buried in the road surface for use, and an inexpensive device can be realized in terms of installation costs. Also, because the number of loop coils is reduced, the time required for new installation, maintenance, and repair can be reduced.

In addition, since the signal frequency for vehicle detection and the signal frequency for vehicle-to-vehicle communication are different, and vehicle-to-vehicle communication is performed at the same time as vehicle detection, vehicle-to-vehicle communication is not limited by the time required for vehicle sensing operation. Can communicate.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus in which the present invention is implemented. FIG. 2 is a block diagram showing the circuit configuration of the ground machine, FIG. 3 is a block diagram showing the circuit structure of the onboard machine, and FIG. 4 is a time chart showing signal waveforms of each part of the circuit of the ground machine shown in FIG. FIG. 5 is a time chart showing signal waveforms of various parts of the circuit of the vehicle-mounted device shown in FIG. 6. Figure 6 is a control flowchart of the transmission control circuit of the ground plane.
Figure 7 shows the transmission control circuit of the on-vehicle device. It is an IJ11 flowchart. 1: Road surface, 2: Loop coil. 3: Roadside, 4: Ground plane. 5: Vehicle, 6: Antenna. 7: On-vehicle unit, 10: Oscillation circuit. 11, 18, 20, 27, 32, 5'5, 41: Bandpass filter circuit. 12: Tuning circuit, 13: Phase comparison circuit. 14: Two-level detection circuit, 15: Switch t16: Integrating circuit, 17: Holding circuit. 19/31: Dual transmitter/receiver. 21/26 fist 36/40: Amplification circuit. 22, 34, 37: Detection circuit. 23/35: Transmission control circuit. 26/38: Demodulation circuit. 25/39: Modulation circuit. Applicant: Tateishi Ki Co., Ltd. Agent: Shigenobu Nakamura, patent attorney

Claims (1)

[Claims] (1) This is a vehicle-to-vehicle communication method performed between a ground plane and an on-vehicle unit of a traveling vehicle, and the ground plane includes an oscillation circuit that is connected to a loop coil buried in the road surface and oscillates at a first frequency. A vehicle detection circuit connected to this oscillation circuit detects a vehicle by changing the frequency of the oscillation circuit when a vehicle arrives, and a vehicle sensing circuit connected to the loop coil and communicating with the on-vehicle device via the loop coil. A transmitting/receiving circuit section that performs operation using a signal of a second frequency different from the first frequency. The vehicle is equipped with an antenna and an on-vehicle device that is connected to the antenna and includes a transmission/reception circuit unit that communicates with the ground device. A vehicle-to-vehicle communication system characterized in that a communication operation between the ground plane and the vehicle-mounted device is performed simultaneously with a vehicle sensing operation by the vehicle sensing circuit at a mutually different frequency.