JP2004242081A - Communication equipment between vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce radio wave interference of communication between vehicles with new constitution. <P>SOLUTION: This communication equipment between vehicles compares the receiving strength of a first polarization component with that of a second polarized component included in a radio wave received from a vehicle ahead, performs transmission and reception by the polarization component with the higher receiving strength between the first and second polarization components on the basis of the above comparison, and performs communication with a vehicle behind by the polarization component with the lower receiving strength. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inter-vehicle communication device.
[0002]
[Prior art]
Conventionally, it has been studied to realize inter-vehicle communication using one frequency. In this case, if a row composed of a large number of vehicles is densely connected to perform vehicle-to-vehicle communication, a device for avoiding radio wave interference due to each communication is required. As a device for this, it is conceivable to separate one frequency into a plurality of channels using, for example, a time division multiplexing (TDMA) method or a code division multiplexing (CDMA) method.
[0003]
[Problems to be solved by the invention]
However, realizing such a multiplexing system requires complicated control such as confirmation of channel usage and management of assigned channels.
[0004]
In view of the above, an object of the present invention is to reduce radio wave interference of inter-vehicle communication with a novel configuration.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a transmission / reception unit that performs wireless transmission / reception with a front vehicle and a rear vehicle in a communication platoon of inter-vehicle communication, and a radio wave that the transmission / reception unit receives from the front vehicle. Comparing means for comparing the reception intensities of the first polarization component and the second polarization component included in the first and second polarization components, based on a comparison between the first polarization component and the second polarization component. The transmission / reception in which the transmission / reception means performs transmission to the front vehicle using the polarization component having the higher reception intensity and the transmission / reception means performs transmission / reception with the rear vehicle using the polarization component having the lower reception intensity. And a control unit.
[0006]
Thereby, the inter-vehicle communication device performs transmission and reception with the front using the polarization received from the vehicle in front, and performs transmission and reception with the polarization different from that for communication with the vehicle behind. In the inter-vehicle communication by the platoon of vehicles equipped with the inter-vehicle communication device, the polarization used between the two vehicles is alternated, and the radio wave interference of the inter-vehicle communication can be reduced.
[0007]
Further, the invention according to claim 2 is the inter-vehicle communication device according to claim 1, wherein when the vehicle exits from the communication platoon of the inter-vehicle communication to which the own vehicle belongs, based on information on the position of the own vehicle in the communication corps, A front vehicle that switches a transmission / reception polarization based on a command from the vehicle-to-vehicle communication and further transmits a transmission / reception polarization switching command to a vehicle in front of the vehicle; Features.
[0008]
As a result, when one vehicle leaves the communication platoon, a platoon of inter-vehicle communication in which polarization alternates quickly is formed.
[0009]
According to a third aspect of the present invention, in the inter-vehicle communication apparatus according to the first or second aspect, when the vehicle enters a communication line of the vehicle-to-vehicle communication, the vehicle-to-vehicle communication is performed based on information on a position of the own vehicle in the communication line. The vehicle further includes an interrupt control unit that transmits a command to switch transmission / reception polarization to a preceding vehicle that transmits a command to switch transmission / reception polarization to a vehicle in front of the device. And
[0010]
As a result, when one vehicle interrupts the communication train, a train of inter-vehicle communication in which the polarization is alternately formed quickly is formed.
[0011]
According to a fourth aspect of the present invention, there is provided the inter-vehicle communication device according to any one of the first to third aspects, wherein the vehicle at the head of the communication group to which the own vehicle belongs and the last vehicle in the front communication group. When approaching, based on the polarization of the reception from the last vehicle, switches the transmission / reception polarization based on the command by the inter-vehicle communication, and further transmits the command to switch the transmission / reception polarization to the vehicle ahead. The vehicle according to claim 1, further comprising a coupling control unit configured to transmit a command to switch polarization between transmission and reception to the vehicle.
[0012]
As a result, when the two communication platoons are combined, a platoon of inter-vehicle communication in which the polarization alternates quickly is formed.
[0013]
According to a fifth aspect of the present invention, in the vehicle-to-vehicle communication apparatus according to the fourth aspect, the coupling control means further includes: the own vehicle in a communication group consisting of a communication group to which the own vehicle belongs and the front communication group; Based on the information related to the position of the vehicle, switches the transmission and reception polarization based on the command by the inter-vehicle communication, further transmits the command to switch the transmission and reception polarization to the vehicle ahead, the command to switch the transmission and reception polarization to the last vehicle, Is provided.
[0014]
According to a sixth aspect of the present invention, there is provided a transmission / reception unit that wirelessly receives from a preceding vehicle in a communication train of inter-vehicle communication and wirelessly transmits to a following vehicle, and a radio wave received by the transmitting / receiving unit from the preceding vehicle. Comparing means for comparing the reception intensity of the first polarization component and the reception intensity of the second polarization component; and comparing the reception intensity of the first polarization component and the second polarization component based on the comparison of the comparison means. And a transmission control means for causing the transmission / reception means to transmit to the rear vehicle with the lower polarization component.
[0015]
Thereby, the inter-vehicle communication device performs transmission and reception with the front using the polarization received from the vehicle in front, and performs transmission and reception with the polarization different from that for communication with the vehicle behind. In inter-vehicle communication by a row of vehicles equipped with an inter-vehicle communication device, the polarization used between the two vehicles is alternated, so that the radio wave interference of the inter-vehicle communication can be reduced.
[0016]
According to a seventh aspect of the present invention, in the inter-vehicle communication device according to the sixth aspect, when the vehicle exits from the communication group of the inter-vehicle communication to which the own vehicle belongs, the polarization of transmission and reception is switched based on a command by the inter-vehicle communication. A rear vehicle that transmits a command to switch transmission / reception polarization to the other vehicle is provided with an exit control unit that transmits a command to switch transmission / reception polarization.
[0017]
As a result, when one vehicle leaves the communication platoon, a platoon of inter-vehicle communication in which polarization alternates quickly is formed.
[0018]
According to an eighth aspect of the present invention, in the inter-vehicle communication apparatus according to the sixth or seventh aspect, when the vehicle enters the communication platoon of the inter-vehicle communication, the polarization of transmission and reception is switched based on a command by the inter-vehicle communication. An interrupt control unit for transmitting a command for switching transmission and reception polarization to a rear vehicle that transmits a command for switching transmission and reception polarization to the vehicle is provided.
[0019]
As a result, when one vehicle interrupts the communication train, a train of inter-vehicle communication in which the polarization is alternately formed quickly is formed.
[0020]
Further, the invention according to claim 9 is a transmission / reception means for wirelessly receiving from a preceding vehicle and wirelessly transmitting to a following vehicle, a specifying means for specifying a traveling speed of the own vehicle, and Power control means for causing the transmission / reception means to wirelessly transmit / receive with transmission power having a positive correlation.
[0021]
Generally, there is a positive correlation between the speed of the vehicle and the inter-vehicle distance, so that the inter-vehicle force and the intensity of the transmission power have a positive correlation. Can be. Therefore, it is possible to reduce radio wave interference of the inter-vehicle communication.
[0022]
According to a tenth aspect of the present invention, in the inter-vehicle communication device according to the ninth aspect, the power control unit sets the intensity of the transmission power to be greater than zero when the running speed specified by the specifying unit is zero. It is characterized by doing.
[0023]
This enables communication even when the vehicle stops running.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
FIG. 1 shows a configuration of an inter-vehicle communication device 1 according to a first embodiment of the present invention. The inter-vehicle communication device 1 according to the present embodiment is for performing wireless communication with the inter-vehicle communication device 1 of a vehicle in front of and behind the own vehicle in a vehicle platoon. A row of vehicles is a row formed by a group of vehicles arranged in series in the traveling direction. FIG. 2 shows a conceptual diagram of a row of vehicles 2 on which the inter-vehicle communication device 1 is mounted. The row of vehicles 2 in the figure is a row. Arrows between the vehicles 2 in the platoon represent communication between the vehicles 2. In the present embodiment, as the communication between the vehicles 2 in the platoon, vertical polarization and horizontal polarization are alternately used from the beginning to the end of the platoon.
[0025]
The inter-vehicle communication device 1 includes a front A antenna 11, a front B antenna 12, a rear B antenna 13, a rear A antenna 14, a level comparison unit 15, switches 16 to 23, a front transmission unit 24, a front reception unit 25, and a rear transmission unit 26. , A rear receiving unit 27, a control unit 28, a memory 29, and an input device 30.
[0026]
The front A antenna 11 is an antenna for transmitting and receiving a radio wave to and from the front of the vehicle, and has a polarization characteristic that enables transmission and reception of a vertically polarized component of the radio wave. The front B antenna 12 is an antenna for transmitting and receiving a radio wave to and from the front of the vehicle, and has a polarization characteristic that enables transmission and reception of a horizontally polarized component of the radio wave.
[0027]
The rear B antenna 13 is an antenna for transmitting and receiving a radio wave to and from the rear of the vehicle, and has a polarization characteristic that enables transmission and reception of a horizontally polarized component of the radio wave. The rear A antenna 14 is an antenna for transmitting and receiving radio waves to and from the rear of the vehicle, and has a polarization characteristic that enables transmission and reception of a vertically polarized component of the radio waves.
[0028]
As the type of antenna, a flat or small antenna such as a patch antenna or a chip dielectric antenna is used. In the case of such a small antenna, it is easy to mount it on a vehicle. FIG. 3 shows the mounting positions of these antennas on the vehicle 2. The front A antenna 11 and the front B antenna 12 are installed in a front bumper portion of the vehicle 2, and the rear B antenna 13 and the rear A antenna 14 are installed in a rear bumper portion. By doing so, there is no obstacle to communication using the antenna, and a good communication state can be maintained.
[0029]
The switch 16 is a switch that controls whether the front A antenna 11 is connected to the switch 20 or the switch 21, and the switching is controlled by the control unit 28.
[0030]
The switch 17 is a switch that controls whether the front B antenna 12 is connected to the switch 20 or the switch 21, and the switching is controlled by the control unit 28.
[0031]
The switch 18 is a switch that controls whether the rear B antenna 13 is connected to the switch 22 or the switch 23, and the switching is controlled by the control unit 28.
[0032]
The switch 19 is a switch that controls whether the rear A antenna 14 is connected to the switch 22 or the switch 23, and the switching is controlled by the control unit 28.
[0033]
The switch 20 connects the forward transmission unit 24 to the switch 16 when a high signal (indicated as H in the figure) is input from the level comparison unit 15 and receives a low signal (indicated as L in the figure) when input. The front transmitter 24 is connected to the switch 17.
[0034]
The switch 21 connects the front receiving unit 25 to the switch 16 when a high signal is input from the level comparing unit 15, and connects the front receiving unit 25 to the switch 17 when a low signal is input.
[0035]
The switch 22 connects the rear transmitter 26 to the switch 18 when a high signal is input from the level comparator 15, and connects the rear transmitter 26 to the switch 19 when a low signal is input.
[0036]
The switch 23 connects the rear receiver 27 to the switch 18 when a high signal is input from the level comparator 15, and connects the rear receiver 27 to the switch 19 when a low signal is input.
[0037]
The forward transmission unit 24 performs D / A modulation, amplification, and frequency conversion on the transmission data input from the control unit 28, and outputs a transmission signal to the switch 20 according to a communication method of inter-vehicle communication.
[0038]
The forward receiving unit 25 performs frequency conversion, amplification, demodulation, and A / D conversion on the signal input from the switch 21 and outputs the signal to the control unit 28 as received data.
[0039]
The rear transmission unit 26 performs D / A modulation, amplification, and frequency conversion on the transmission data input from the control unit 28, and outputs a transmission signal to the switch 22 according to a communication method of inter-vehicle communication.
[0040]
The rear receiving unit 27 performs frequency conversion, amplification, demodulation, and A / D conversion on the signal input from the switch 23, and outputs the signal to the control unit 28 as received data.
[0041]
The memory 29 includes a storage medium such as a RAM, a ROM, and a flash memory (not shown), and is controlled by the control unit 28 to read and write.
[0042]
The input device 30 outputs to the control unit 28 a signal based on an operation such as a button press by a user of the inter-vehicle communication device 1.
[0043]
The level comparison unit 15 has a CPU, ROM, RAM, and real-time clock (not shown). The CPU reads and executes a program stored in the ROM, and reads / writes information from / to the RAM as necessary. Then, the reset signal is output to the real-time clock, and the signal is output to the switches 20 to 23. The real-time clock transmits an interrupt signal to the CPU when a predetermined time (for example, one second) elapses, and when a reset signal is input from the CPU, initializes the measurement time and restarts the time measurement from the beginning.
[0044]
The control unit 28 operates by reading and executing a predetermined program from the ROM or the flash memory of the memory 29, reads information from the ROM, the RAM, or the flash memory of the memory 29 as needed for the operation, and Write information to the flash memory. The control unit 28 outputs data to the front transmission unit 24 and the rear transmission unit 26 as necessary for the operation, receives data from the front reception unit 25 and the rear reception unit 27, and outputs the data to the level comparison unit 15, A control signal is output to switches 16-19. In addition, the control unit 28 is configured to receive a blinker signal, thereby detecting blinking of the blinker of the own vehicle. The control unit 28 can detect an output signal to the switches 20 to 23 of the level comparison unit 15 via a signal line (not shown).
[0045]
The programs executed by the control unit 28 include establishing a link with an inter-vehicle communication device mounted on the preceding and following vehicles in the platoon, and exchanging information in the platoon using the established link. The platoon information exchanged in the platoon includes an identification number of each vehicle, a position in the platoon, the total number of vehicles constituting the platoon, and the like. As the vehicle identification number, for example, a serial number or the like recorded in advance in the memory 29 of the inter-vehicle communication device 1 can be used.
[0046]
The position of the own vehicle in the platoon can be specified by receiving information on the order of the own vehicle in the platoon, for example, the order of the preceding vehicle from the head of the preceding vehicle in the platoon and adding 1 thereto. it can. The total number of vehicles in the platoon, that is, the number of vehicles in the platoon, can be specified by, for example, receiving the information from the preceding and following vehicles. The vehicle-to-vehicle communication device 1 that has received these pieces of information transmits the number of vehicles in the platoon before and after, and transmits the order from the head of the own vehicle to the rear. Thus, all vehicles in the platoon can specify the number of vehicles in the platoon and the position of the own vehicle in the platoon.
[0047]
Note that the control unit 28 of the inter-vehicle communication device 1 at the head of the platoon can identify that it is at the head of the vehicle by detecting that it cannot receive a signal of a predetermined level or more from the front of the vehicle. . Further, the control unit 28 of the inter-vehicle communication device 1 mounted on the last vehicle of the platoon detects that the signal of a predetermined level or more cannot be received from the rear of the own vehicle, so that the own vehicle is at the last position. Can be specified. Further, the control unit 28 of the last vehicle can specify the number of vehicles in the platoon from the fact that the own vehicle is the last and the order from the head of the own vehicle.
[0048]
Further, at the time of wireless transmission, the control unit 28 connects the front A antenna 11 and the switch 20, connects the front B antenna 12 and the switch 20, connects the rear B antenna 13 and the switch 22, and connects the rear A antenna 14 A control signal is output to the switches 16 to 19 so that the switch and the switch 22 are connected. Further, at the time of wireless reception, the control unit 28 connects the front A antenna 11 and the switch 21, connects the front B antenna 12 and the switch 21, connects the rear B antenna 13 and the switch 23, and A control signal is output to the switches 16 to 19 so that the switch and the switch 23 are connected.
[0049]
When receiving a polarization switching signal, which will be described later, from the rear vehicle in the communication, the control unit 28 transmits a similar switching signal to the preceding vehicle, and then outputs a control signal to the level comparison unit 15.
[0050]
With the inter-vehicle communication device 1 having the above-described configuration, when the level comparison unit 15 outputs a high signal to the switches 20 to 23, during wireless transmission, the output of the front transmission unit 24 radiates forward from the front A antenna 11 toward the host vehicle. The output of the rear transmitter 26 is radiated from the rear B antenna 13 to the rear of the host vehicle. At this time, at the time of wireless reception, a signal received by the front A antenna 11 is input to the front receiving unit 25, and a signal received by the rear B antenna 13 is input to the rear receiving unit 27. That is, wireless transmission / reception is performed with the vehicle in front using vertical polarization, and wireless transmission / reception is performed with the vehicle behind using horizontal polarization.
[0051]
Also, when the level comparing section 15 outputs a low signal to the switches 20 to 23, during wireless transmission, the output of the front transmitting section 24 is radiated forward from the front B antenna 12 and the output of the rear transmitting section 26 is rearward. It is radiated from the A antenna 14 to the rear of the vehicle. At this time, at the time of wireless reception, a signal received by the front B antenna 12 is input to the front receiving unit 25, and a signal received by the rear A antenna 14 is input to the rear receiving unit 27. That is, wireless transmission / reception is performed with the vehicle in front using horizontal polarization, and wireless transmission / reception is performed with the vehicle behind using vertical polarization.
[0052]
Next, FIG. 4 shows a flowchart of a program that the CPU of the level comparing section 15 reads out from the ROM and executes. The operation of the level comparing section 15 will be described with reference to this flowchart.
[0053]
First, when the processing is started by supplying power to the level comparing unit 15, in step 203, the time for measurement is initialized. Specifically, it outputs a reset signal in response to a real-time clock.
[0054]
Next, in step 205, it is determined whether or not a control signal has been received from the control unit 28. If the control signal has been received, a predetermined flag is set in the RAM in the level comparing section 15 in step 210, and the process returns to step 203. If the control signal has not been received, the process proceeds to step 215.
[0055]
In step 215, it is determined whether a predetermined time has elapsed. Specifically, it is determined whether or not an interrupt signal has been received from the real-time clock. If not, the process returns to step 203.
[0056]
If an interrupt signal has been received, the process proceeds to step 220, where it is determined whether the predetermined flag mentioned in step 210 has been set. If the flag has been set, the process proceeds to step 245; otherwise, the process proceeds to step 225.
[0057]
In step 245, the CPU inverts the signal level currently output to the switches 20 to 23 by the CPU. That is, the output is switched to a high signal if a low signal is output, and to a low signal if a high signal is output. Then, in step 250, the flag is reset, and then the process returns to step 203.
[0058]
In step 225, it is determined whether or not both the input signal reception level from the front A antenna 11 and the signal reception level from the front B antenna 12 are lower than a predetermined level. If both are low, the process returns to step 203. If at least one of them is not low, the process proceeds to step 230.
[0059]
In step 230, the received signal level from the front A antenna 11 and the received signal level from the front B antenna 12 are compared. If the level from the front A antenna 11 is high, the process proceeds to step 240, the signals output to the switches 20 to 23 are set to low level, and then the process returns to step 203.
If the level from the front B antenna 12 is high, the process proceeds to step 235, where the signals output to the switches 20 to 23 are set to high level, and thereafter, the process returns to step 203.
[0060]
With the above processing, the level comparison unit 15 periodically compares the signal input from the switch 16 with the signal input from the switch 17, and outputs a signal to be output to the switches 20 to 23 when the signal level from the switch 16 is high. When the signal level from the switch 17 is high, the signal output to the switches 20 to 23 is low. However, when both the level of the signal from the switch 16 and the level of the signal from the switch 17 are lower than a predetermined threshold, the current output signals to the switches 20 to 23 are held. When the control signal is received from the control unit 28, the high and low outputs to the switches 20 to 23 are inverted from the current state by one cycle regardless of the signal levels from the switches 16 and 17.
[0061]
Next, a description will be given of a program that is read out from the ROM of the memory 29 and executed by the control unit 28 when the own vehicle newly interrupts the vehicle platoon. FIG. 5 shows a flowchart of this program.
[0062]
The processing in this figure is started when electric power is supplied to the inter-vehicle communication device 1, and is executed in parallel with another program executed by the control unit 28. In this program, first, at step 310, it is determined whether or not the vehicle has entered the platoon. Specifically, the levels of the radio signals received from the rear and the front at the time of the previous determination in step 310 are both equal to or less than a predetermined threshold value, and the level of the radio signal from at least one of them is determined at the time of the current determination. It is determined whether or not it has reached a predetermined threshold or more. Note that, in the determination immediately after the start of this processing, the determination is made on the assumption that the levels of the radio signals received from the rear and the front are both equal to or less than a predetermined threshold at the time of the previous determination. In order for the control unit 28 to execute this determination, the step 28 detects the reception level from the front and the rear in step 310 and records the value in the RAM.
This process is repeated until it is determined that the vehicle has entered the platoon.
[0063]
If it is determined that the vehicle has entered the platoon, the process proceeds to step 320, and it is determined whether or not the position of the vehicle in the platoon is before the center of the platoon, that is, before the middle position. This determination is made based on information on the number of vehicles in the platoon and the position of the own vehicle in the platoon obtained by the processing of the control unit 28 described above.
[0064]
If it is determined that it is before the center, the process proceeds to step 330, where a polarization switching signal is transmitted to the preceding vehicle, and then the process returns to step 310. If it is determined that it is not before the center, the process returns to step 310.
[0065]
Next, a description will be given of a program that is read out from the ROM of the memory 29 and executed by the control unit 28 when the own vehicle leaves the vehicle platoon. FIG. 6 shows a flowchart of this program.
[0066]
The processing in this figure is started when electric power is supplied to the inter-vehicle communication device 1, and is executed in parallel with another program executed by the control unit 28. The program first determines in step 410 whether the vehicle is about to leave the platoon. Specifically, it is determined whether communication is currently being performed in the platoon and there is an input of a turn signal. This process is repeated until it is determined that the player is about to leave the platoon.
[0067]
When it is determined that the vehicle is about to leave the platoon, that is, when the vehicle exits the platoon, the process proceeds to step 415, and determines whether the own vehicle position is at the beginning or end of the platoon. This determination is made based on information on the number of vehicles in the platoon and the position of the own vehicle in the platoon obtained by the processing of the control unit 28 described above. If the host vehicle position is the first or last position, the process returns to step 410; otherwise, the process proceeds to step 420.
[0068]
The processing in steps 420 and 430 is equivalent to the processing in steps 320 and 330 in FIG. 5, respectively.
[0069]
In the vehicle-to-vehicle communication device 1 having the above-described configuration and operation, when the vehicles equipped with the vehicle-to-vehicle communication device 1 are performing communication in a platoon, the processes of steps 230, 235, and 240 in the operation of the level comparison unit 15 are performed. And by operating the switches 20 to 23, if the signal level from the front A antenna 11 is higher than the signal level from the front B antenna 12, that is, if the transmission from the front vehicle is based on vertical polarization, The transmission / reception of the vehicle uses a front A antenna 11 for vertical polarization, and the transmission / reception to / from a rear vehicle uses a rear B antenna 13 for horizontal polarization. If the signal level from the front B antenna 12 is higher than the signal level from the front A antenna 11, that is, if the transmission from the front vehicle is based on horizontal polarization, the transmission and reception with the front vehicle is for horizontal polarization. A front B antenna 12 is used, and a transmission / reception with a rear vehicle uses a rear A antenna 14 for vertical polarization.
[0070]
Thereby, the inter-vehicle communication device performs transmission and reception with the front using the polarization received from the vehicle in front, and performs transmission and reception with the polarization different from that for communication with the vehicle behind. In the inter-vehicle communication by the platoon of vehicles equipped with the inter-vehicle communication device, the polarization used between the two vehicles alternates as shown in FIG. 2, so that the radio wave interference of the inter-vehicle communication can be reduced.
[0071]
Next, the operation of the platoon when a vehicle equipped with the inter-vehicle communication device 1 newly enters the platoon will be described.
[0072]
First, when a vehicle outside the platoon enters the platoon, the control unit 28 receives a signal from the front, establishes a wireless link with the preceding vehicle with the same polarization as that of the received signal, and The information on the number of vehicles in the platoon and the position of the preceding vehicle in the platoon is obtained from the information, and the position of the own vehicle in the platoon is specified.
[0073]
The control unit 28 transmits a polarization switching signal to the preceding vehicle when the position of the own vehicle in the platoon is before the center by the processing in FIG. The control unit 28 of the inter-vehicle communication device 1 that has received the switching signal transmits the polarization switching signal to the vehicle further ahead as described above, and then outputs the control signal to the level comparing unit 15. The CPU of the level comparison unit 15 to which the control signal has been input sets a flag in step 210, and inverts the current output level in step 245 after a predetermined time has elapsed. As a result, the polarization of the backward transmission from the inter-vehicle communication device 1 becomes different from that before. However, the output level is inverted only once per reception of the switching signal by the process of step 250, and the output level when it is determined in step 215 that the predetermined time has elapsed is normal. However, at this time, the output level of the vehicle ahead of the vehicle has already been inverted, so that the polarization of the vehicle maintains the state at the time of the output level inversion. By repeating such processing in order up to the first vehicle, the polarization of transmission and reception of all vehicles in front of the vehicles in the platoon is switched. In addition, the transmission and reception polarizations of all vehicles behind the vehicles in the platoon are not switched.
[0074]
As a result, even if a vehicle interrupts the platoon, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0075]
In the processing of FIG. 5 by the control unit 28, when the position of the interrupted vehicle in the platoon is not before the center, the polarization switching signal is not transmitted to the vehicle in front. Therefore, the polarization of transmission and reception is not switched in all vehicles before the vehicle that has interrupted. Also, since the interrupting vehicle transmits a different polarization to the rear than the preceding vehicle, the rear vehicle will receive a signal of a different polarization from the polarization received until interruption. Is switched. This switching is repeated up to the last vehicle in the platoon, so that the transmission and reception polarization of all vehicles behind the vehicle in the platoon is switched. As a result, even if a vehicle interrupts the platoon, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0076]
The operation of the platoon when the vehicle equipped with the inter-vehicle communication device 1 leaves the platoon will be described. First, when a turn signal is operated by an occupant in a vehicle that is about to leave the platoon, the control unit 28 of the vehicle performs the processing shown in FIG. Is not performed. In this case, even if the first vehicle or the rear vehicle in the platoon leaves the platoon, there is no change in the transmission / reception polarization of other vehicles.
[0077]
Also, in the processing of FIG. 6, even when the host vehicle is neither at the head nor at the end and is not before the center of the platoon, the processing for evacuation is not particularly performed. In this case, the vehicle behind the exiting vehicle receives a polarization from the vehicle ahead of the exiting vehicle, and therefore receives a signal of a polarization different from the polarization received so far. Is switched. This switching is repeated until the end of the platoon, and as a result, the transmission / reception polarization of all vehicles behind the vehicle that has entered the platoon is switched.
[0078]
In the processing of FIG. 6, when the own vehicle is neither the first nor the last and is before the center of the platoon, a polarization switching signal is transmitted to the preceding vehicle. In this case, similarly to the case where the polarization switching signal is transmitted to the preceding vehicle when the vehicle enters the platoon, the transmission and reception polarization of all the vehicles in front of the exiting vehicle is switched.
[0079]
As a result, even if a vehicle comes out of the platoon, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0080]
Next, when the vehicle equipped with the inter-vehicle communication device 1 is at the head of the row, there is another row in front of the vehicle, and the end of the row approaches, and the two rows become one, that is, The operation of the inter-vehicle communication device 1 of the leading vehicle when the platoons are combined will be described.
[0081]
First, the control unit 28 of the vehicle-to-vehicle communication device 1 of the vehicle has information on the number of vehicles constituting the platoon of the own vehicle and the position of the own vehicle in the platoon by communication between the platoons.
[0082]
FIG. 7 shows, as a flowchart, a program for connecting the platoons, which is read out from the ROM by the control unit 28 and started to be executed when the own vehicle comes first.
[0083]
First, in step 510, it is determined whether or not a convoy is approaching from the front. Specifically, it is determined whether or not a signal has been received with any polarization from the front. The process of step 510 is repeated until it is determined that the platoon is approaching. If it is determined that the platoon is approaching, the process proceeds to step 515.
[0084]
In step 515, the polarization transmitted by the own vehicle forward in the platoon to which the current vehicle belongs is the same as the polarization transmitted from the last inter-vehicle communication device 1 in the front platoon. Is determined. Specifically, it is determined whether the signal level from the level comparison unit 15 to the switches 20 to 23 is the same or has changed. If the polarizations are the same, the process ends. If the polarization has changed, the process proceeds to step 530.
[0085]
In step 530, it is determined whether or not the vehicle position is before the center. Here, “before the center” is determined based on whether or not it is before the center in one row where the front row and the own row are combined. Specifically, it is determined whether or not the number of vehicles constituting the platoon of the own platoon is equal to or greater than the number of vehicles constituting the platoon received from the preceding vehicle. If not before the center, the process ends.
[0086]
If it is before the center, the process proceeds to step 530, and transmits a polarization switching signal to the preceding vehicle. As a result, similarly to step 330 in FIG. 5 and step 430 in FIG. 6, the polarization used by all vehicles in the front platoon is switched.
[0087]
As a result, even when the two platoons are combined, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0088]
In this embodiment, the antennas are mounted at the positions as shown in FIG. 3, but the front A antenna 11 and the front B antenna 12 are installed on the dashboard of the vehicle 2 as shown in FIG. The antenna 13 and the rear A antenna 14 may be installed on the rear dashboard or the roof of the vehicle 2, or four antennas may be collectively installed on the roof of the vehicle 2 as shown in FIG.
[0089]
(2nd Embodiment)
FIG. 10 shows a configuration of an inter-vehicle communication device 3 according to the second embodiment of the present invention. The inter-vehicle communication device 3 includes a front A antenna 11, a front B antenna 12, a rear B antenna 13, a rear A antenna 14, a level comparison unit 15, a front reception unit 25, a rear transmission unit 26, a control unit 28, a memory 29, an input It comprises an apparatus 30 and switches 31 and 32.
[0090]
The difference between the inter-vehicle communication device 3 of the present embodiment and the inter-vehicle communication device 1 of the first embodiment is that the inter-vehicle communication device 1 can perform both transmission and reception before and after the own vehicle, while the inter-vehicle communication device 3 Only reception can be performed from the front of the vehicle, and only transmission can be performed behind the vehicle. In FIG. 10, components having the same functions as in FIG. 1 are given the same reference numerals as in FIG.
[0091]
The switch 31 connects the front receiving unit 25 to the front A antenna 11 when a high signal is input from the level comparing unit 15, and connects the front receiving unit 25 to the front B antenna 12 when a low signal is input.
[0092]
The switch 32 connects the rear transmitting unit 26 to the rear B antenna 13 when a high signal is input from the level comparing unit 15, and connects the rear transmitting unit 26 to the rear A antenna 14 when a low signal is input.
[0093]
Next, the operation of the inter-vehicle communication device 3 will be described only for the portions different from those of the first embodiment.
[0094]
In the present embodiment, since the inter-vehicle communication device 3 cannot transmit to the front, the information on the number of vehicles constituting the platoon is not exchanged in the platoon.
[0095]
The control unit 28 receives a signal from the inter-vehicle communication device 3 of the front vehicle and transmits the signal to the inter-vehicle communication device 3 of the rear vehicle. The control signal is transmitted to the vehicle, and then a control signal is output to the level comparison unit 15. In addition, the control unit 28 executes the programs shown in FIGS.
[0096]
FIG. 11 is a flowchart showing a program read from the ROM of the memory 29 and executed by the control unit 28 of the inter-vehicle communication device 3 when the own vehicle newly interrupts the vehicle platoon.
[0097]
The process in this figure starts when power is supplied to the inter-vehicle communication device 3 and is executed in parallel with another program executed by the control unit 28. In this program, first, in step 610, it is determined whether or not the own vehicle has entered the platoon as in FIG. 5 in the first embodiment. This process is repeated until it is determined that the vehicle has entered the platoon.
[0098]
If it is determined that the vehicle has entered the platoon, the process proceeds to step 630, where a polarization switching signal is transmitted to the vehicle behind, and then the process returns to step 610.
[0099]
FIG. 12 is a flowchart showing a program read from the ROM of the memory 29 and executed by the control unit 28 when the own vehicle leaves the vehicle platoon.
[0100]
The process in this figure starts when power is supplied to the inter-vehicle communication device 3 and is executed in parallel with another program executed by the control unit 28. In this program, first, in step 710, it is determined whether or not the own vehicle is about to drop out of the platoon as in step 410 of FIG. This process is repeated until it is determined that the player is about to leave the platoon.
[0101]
When it is determined that the player is about to leave the platoon, that is, when the player leaves the platoon, the process proceeds to step 730, and a switching signal is transmitted backward. Then, the process returns to step 710.
[0102]
In the vehicle-to-vehicle communication device 3 having the above-described configuration and operation, when the vehicle equipped with the vehicle-to-vehicle communication device 1 is performing communication in a platoon, the processes of steps 230, 235, and 240 in the operation of the level comparison unit 15 are performed. And by operating the switches 31 and 32, if the signal level from the front A antenna 11 is higher than the signal level from the front B antenna 12, that is, if the transmission from the front vehicle is based on vertical polarization, Is received by the front A antenna 11 for vertical polarization, and the transmission to the rear vehicle is performed by the rear B antenna 13 for horizontal polarization. If the signal level from the front B antenna 12 is higher than the signal level from the front A antenna 11, that is, if the transmission from the front vehicle is due to horizontal polarization, the reception from the front vehicle is for horizontal polarization. A front B antenna 12 is used, and a rear A antenna 14 for vertical polarization is used for transmission to a rear vehicle.
[0103]
Thereby, the inter-vehicle communication device performs transmission and reception with the front using the polarization received from the vehicle in front, and performs transmission and reception with the polarization different from that for communication with the vehicle behind. In the inter-vehicle communication by the platoon of vehicles equipped with the inter-vehicle communication device, the polarization used between the two vehicles alternates as shown in FIG. 2, so that the radio wave interference of the inter-vehicle communication can be reduced.
[0104]
Next, the operation of the platoon when a vehicle equipped with the inter-vehicle communication device 3 newly enters the platoon will be described.
[0105]
First, when a vehicle outside the platoon enters the platoon, the control unit 28 receives a signal from the front and transmits a polarization switching signal to the rear vehicle by the processing of FIG. The control unit 28 of the inter-vehicle communication device 3 on the side that has received the switching signal transmits the polarization switching signal to the vehicle further behind as described above, and then outputs the control signal to the level comparing unit 15. The CPU of the level comparison unit 15 to which the control signal has been input sets a flag in step 210, and inverts the current output level in step 245 after a predetermined time has elapsed. As a result, the polarization of the backward transmission from the inter-vehicle communication device 1 becomes different from that before. However, the output level is inverted only once per reception of the switching signal by the process of step 250, and the output level when it is determined in step 215 that the predetermined time has elapsed is normal. However, at this time, since the transmission polarization has already been switched by the vehicle further ahead of the vehicle, the state of the polarization of the vehicle at the time of the output level reversal is maintained. By repeating such processing in order up to the first vehicle, the polarization of transmission / reception of all vehicles behind the vehicles in the platoon is switched. As a result, even if a vehicle interrupts the platoon, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0106]
The operation of the platoon when the vehicle equipped with the inter-vehicle communication device 1 leaves the platoon will be described. First, when an occupant operates a winker in a vehicle that is about to leave the platoon, the control unit 28 of the vehicle transmits a polarization switching signal to the rear vehicle by the processing in FIG. In this case, similarly to the case where the polarization switching signal is transmitted to the preceding vehicle when the vehicle enters the platoon, the transmission and reception polarization of all vehicles behind the exiting vehicle is switched.
[0107]
As a result, even if a vehicle comes out of the platoon, the polarization used between the two vehicles alternates as shown in FIG. 2, so that it is possible to reduce radio wave interference in inter-vehicle communication.
[0108]
(Third embodiment)
Next, a third embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the inter-vehicle communication device 1 of the present embodiment controls the transmission power or the transmission distance of wireless transmission based on the traveling speed of the own vehicle. is there. For this purpose, the inter-vehicle communication device 1 can control the amplification levels of the front transmission unit 24 and the rear transmission unit 26 by a control line not shown in FIG. Further, a signal from a vehicle speed sensor (not shown) that is mounted on the vehicle and acquires and outputs a vehicle speed pulse signal from the engine ECU is input to the control unit 28.
[0109]
Further, in addition to the operations shown in the first embodiment, the control unit 28 reads out the program shown in FIG. 13 from the ROM and executes it. This process starts after power is supplied to the inter-vehicle communication device 1.
[0110]
First, at step 810, the vehicle speed is detected from the input from the vehicle speed sensor. Next, at step 820, the vehicle speed-distance table is referred to. This vehicle speed-distance table is recorded in the ROM of the memory 29 in advance. FIG. 14 shows this vehicle speed-distance table. Each row in the figure represents the speed per hour (displayed in km / h) of the vehicle and the corresponding communication distance (displayed in m).
The communication distance corresponding to each hourly speed corresponds to a moving distance of 2 seconds at each hourly speed. This is based on the fact that an inter-vehicle distance is generally required to be at least 2 seconds. However, when the speed is 0 km / h, the communication distance is not 0 but a finite value. As shown in this table, the communication distance is increasing with an increase in vehicle speed. That is, the vehicle speed and the communication distance have a positive correlation.
[0111]
Next, in step 830, a control signal is output to the front transmission unit 24 and the rear transmission unit 26 so that the transmission power is set to such an extent that the radio wave reaches only the other inter-vehicle communication device 1 within the acquired communication distance. As a result, the vehicle speed and the transmission power also have a positive correlation. Then, the process returns to step 810.
[0112]
By determining the transmission power based on the vehicle speed in this manner, it is possible to prevent transmission with excessive power that is higher than the power required to reach vehicles other than the front vehicle and the rear vehicle, and to control interference in the platoon. Can be. When the vehicle speed is zero, the transmission power is controlled to be greater than zero, so that communication is possible even when the vehicle is stopped. Note that these effects are effective even if different polarizations are not used alternately in the platoon and the same polarization is used.
[0113]
Note that, in the first embodiment of the present invention, the front transmitting unit 24, the front receiving unit 25, the rear transmitting unit 26, and the rear receiving unit 27 constitute a transmitting / receiving unit that performs wireless transmission / reception with the front vehicle and the rear vehicle. .
[0114]
Step 230 of the level comparing section 15 constitutes comparing means for comparing the reception intensity of the first polarization component and the second polarization component included in the radio wave received by the transmitting / receiving means from the vehicle ahead.
[0115]
Further, the processing of steps 235 and 240 is based on this comparing means, and the transmitting and receiving means transmits the first polarized wave component and the second polarized wave component to the vehicle ahead using the higher polarized wave component of the receiving intensity. A transmission / reception control unit is configured to cause the transmission / reception unit to perform transmission / reception to / from a rear vehicle using the polarization component having the lower reception intensity.
[0116]
In addition, when the process of the control unit 28 illustrated in FIG. 6 exits from the communication group of the inter-vehicle communication to which the own vehicle belongs, a command to switch the transmission / reception polarization to the preceding vehicle based on the information regarding the position of the own vehicle in the communication group. Is formed.
[0117]
In addition, when the process of the control unit 28 illustrated in FIG. 5 enters the communication platoon of the inter-vehicle communication, the control unit 28 transmits a command to switch the transmission / reception polarization to the preceding vehicle based on the information regarding the position of the own vehicle in the communication platoon. Constructs interrupt control means.
[0118]
Also, when the process of the control unit 28 shown in FIG. 7 is at the head of the communication team to which the host vehicle belongs and approaches the end of the front communication team, it is based on the polarization of the transmission from the last vehicle. And a coupling control means for transmitting a command to switch the transmission / reception polarization to the preceding vehicle.
[0119]
In the second embodiment, the front receiving unit 25 and the rear transmitting unit 26 constitute a transmitting / receiving unit that wirelessly receives the vehicle from the front vehicle and wirelessly transmits the vehicle to the rear vehicle.
[0120]
Step 230 of the level comparing section 15 constitutes comparing means for comparing the reception intensity of the first polarization component and the second polarization component included in the radio wave received from the vehicle ahead.
[0121]
Further, the processing of steps 235 and 240 is based on the comparison means, and the transmission / reception means transmits to the transmission / reception means with the lower one of the first polarization component and the second polarization component. A transmission control means for performing transmission is configured.
[0122]
In addition, when the process of the control unit 28 shown in FIG. 12 leaves the communication group of the inter-vehicle communication to which the own vehicle belongs, it constitutes an exit control unit that transmits a command to switch the transmission / reception polarization to the rear vehicle.
[0123]
Further, the processing of the control unit 28 shown in FIG. 11 constitutes an interrupt control means for transmitting an instruction to switch the transmission / reception polarization to the rear vehicle when the vehicle enters the communication line of the inter-vehicle communication.
[0124]
Further, in the third embodiment, the processing of step 810 of the control unit 28 shown in FIG.
[0125]
Further, the processing in step 830 of the control unit 28 constitutes power control means for causing the transmitting / receiving means to wirelessly transmit / receive the transmission power having a positive correlation with the traveling speed specified by the specifying means.
[0126]
In each embodiment, the vertical polarization component is the first polarization component, and the horizontal polarization component is the second polarization component. For example, the right 45 ° polarization component and the left 45 ° polarization component are The first and second polarization components may be respectively used, and the right-handed polarization component and the left-handed polarization component may be used as the first and second polarization components, respectively. That is, the first polarization component and the second polarization component may be polarization components that do not interfere with each other.
[0127]
When the right-handed polarization component and the left-handed polarization component are the first and second polarization components, respectively, the two opposite vertexes of the rectangle as shown in the perspective view of FIG. A patch antenna 35 may be used.
[0128]
Also, as shown in the perspective view of FIG. 16, if an antenna having a pattern 38 provided on both sides of a plane plate composed of a dielectric 36 and a ground plate 37 is used, one antenna can transmit and receive radio waves to both the front and rear of the vehicle. It can be carried out.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an inter-vehicle communication device 1 according to a first embodiment of the present invention.
FIG. 2 is a conceptual diagram of a row of vehicles 2 on which the inter-vehicle communication device 1 is mounted.
FIG. 3 is a diagram showing a mounting position of an antenna to a vehicle 2.
FIG. 4 is a flowchart of a program executed by a CPU of a level comparing unit 15;
FIG. 5 is a flowchart of a program executed by a control unit 28 for interrupting a vehicle platoon.
FIG. 6 is a flowchart of a program executed by the control unit 28 when the vehicle leaves the vehicle platoon.
FIG. 7 is a flowchart showing a program executed by the control unit 28 for combining platoons.
FIG. 8 is a diagram showing an attachment position of the antenna to the vehicle 2.
FIG. 9 is a diagram showing a mounting position of the antenna to the vehicle 2.
FIG. 10 is a configuration diagram of an inter-vehicle communication device 3 according to a second embodiment of the present invention.
FIG. 11 is a flowchart showing a program executed by the control unit 28 for interrupting a vehicle platoon.
FIG. 12 is a flowchart showing a program executed by the control unit 28 when the vehicle leaves the vehicle platoon.
FIG. 13 is a flowchart of a program for controlling transmission power according to a vehicle speed.
FIG. 14 is a chart showing a vehicle speed-distance table.
FIG. 15 is a perspective view of a patch antenna.
FIG. 16 is a perspective view of an antenna in which patterns 38 are provided on both surfaces of a flat plate including a dielectric 36 and a ground plate 37;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... inter-vehicle communication apparatus, 2 ... vehicle, 3 ... inter-vehicle communication apparatus,
11: front A antenna, 12: front B antenna,
13: rear B antenna, 14: rear A antenna, 15: level comparison unit,
16-23: switch, 24: forward transmitter, 25: forward receiver,
26: rear transmission unit, 27: rear reception unit, 28: control unit, 29: memory,
30 input device, 31 switch, 32 switch
35: patch antenna, 36: dielectric, 37: ground plane,
38 ... pattern.

Claims (10)

Transmitting and receiving means for wirelessly transmitting and receiving the front vehicle and the rear vehicle within the communication column of the inter-vehicle communication,
Comparing means for comparing the reception intensity of the first polarization component and the second polarization component included in the radio wave received by the transmission / reception means from the preceding vehicle;
Based on the comparison of the comparison means, the first and second polarization components, of the second polarization component, the transmitting and receiving means to transmit to the vehicle ahead in the polarization component of the higher reception intensity, An inter-vehicle communication device comprising: a transmission / reception control unit that causes the transmission / reception unit to perform transmission / reception to / from the rear vehicle with a polarization component having a lower reception intensity. When the vehicle exits from the communication line of the inter-vehicle communication to which the own vehicle belongs, based on the information on the position of the own vehicle in the communication line, the polarization of transmission and reception is switched based on an instruction by the inter-vehicle communication, and the polarization of transmission and reception is further transmitted to the vehicle ahead. The vehicle-to-vehicle communication device according to claim 1, further comprising an exit control unit that transmits a command to switch transmission / reception polarization to a preceding vehicle that transmits a command to switch transmission / reception. When entering the communication line of the vehicle-to-vehicle communication, a command to switch the transmission / reception polarization based on the instruction by the vehicle-to-vehicle communication based on the information on the position of the own vehicle in the communication line, and to switch the transmission / reception polarization to the vehicle ahead. The vehicle-to-vehicle communication device according to claim 1 or 2, further comprising: an interrupt control unit that transmits a command for switching transmission / reception polarization to a preceding vehicle that transmits the transmission signal. When approaching the last vehicle in the front of the communication team to which the host vehicle belongs and approaching the last vehicle in the front of the communication team, the transmission and reception bias is determined based on the polarization of the signal received from the last vehicle and on the basis of the inter-vehicle communication command. The coupling control means for transmitting a command for switching transmission / reception polarization to the last vehicle which transmits a command for switching transmission / reception polarization to a vehicle ahead of the vehicle by switching a wave, further comprising: 3. The inter-vehicle communication device according to any one of 3. The coupling control means further switches the transmission / reception polarization based on a command by inter-vehicle communication, based on information regarding the position of the own vehicle in the communication platoon to which the host vehicle belongs and the front communication platoon. 5. The vehicle-to-vehicle communication according to claim 4, further comprising: coupling control means for transmitting a command for switching transmission / reception polarization to the last vehicle transmitting a command for switching transmission / reception polarization to a vehicle ahead. apparatus. Transmitting and receiving means for wirelessly receiving from a preceding vehicle in a communication column of inter-vehicle communication and wirelessly transmitting to a following vehicle;
Comparing means for comparing the reception intensity of the first polarization component and the second polarization component included in the radio wave received by the transmission / reception means from the preceding vehicle;
A transmission that causes the transmission / reception unit to perform transmission to the rear vehicle with a lower polarization component of the first polarization component and the second polarization component based on the comparison by the comparison unit. And a control unit. When the vehicle exits from the communication platoon of the inter-vehicle communication to which the own vehicle belongs, the polarization of the transmission and reception is switched to the rear vehicle, which switches the transmission and reception polarization based on the instruction by the inter-vehicle communication, and further transmits the instruction to switch the transmission and reception polarization to the rear vehicle. The inter-vehicle communication device according to claim 6, further comprising an exit control unit that transmits a switching instruction. When entering the communication platoon of inter-vehicle communication, it switches the transmission and reception polarization based on the instruction by the inter-vehicle communication, and further issues a command to switch the transmission and reception polarization to the following vehicle, which transmits a command to switch the transmission and reception polarization to the following vehicle. 8. The inter-vehicle communication device according to claim 6, further comprising an interrupt control unit for transmitting. Transmitting and receiving means for wirelessly receiving from a preceding vehicle and wirelessly transmitting to a following vehicle;
Specifying means for specifying the traveling speed of the own vehicle;
An inter-vehicle communication device, comprising: a power control unit that causes the transmitting / receiving unit to perform wireless transmission / reception with transmission power having a positive correlation with the traveling speed specified by the specifying unit. 10. The inter-vehicle communication device according to claim 9, wherein the power control unit sets the intensity of the transmission power to be greater than zero when the running speed specified by the specifying unit is zero.

Images