JP2007189436A - Car to car communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a car-to-car communication device for exchanging information between vehicles with no long time required for specifying a communication partner, and with the effect of elimination of interference of radar waves. <P>SOLUTION: The device comprises a timing matching means which allows a radar device 12 of an own vehicle 10 to transmit radar waves at a timing matched with a satellite time information received from the satellite of a positioning system; a detecting means for detecting positional information of other vehicle from the beat between the radar waves transmitted from the radar device 22 of other vehicle 20 at the timing matched with the satellite time information, and the radar waves transmitted from the laser device of the own vehicle at the timing matched with the satellite time information; a transmitting means for transmitting radar waves multiplexed with communication information if other vehicle is present within a specified range from the own vehicle, based on the positional information for the other vehicle; and a receiving means for splitting and extracting a communication information from the radar waves received from the other vehicle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inter-vehicle communication device, and more particularly to an inter-vehicle communication device that transmits and receives inter-vehicle communication data using a radar.

  In-vehicle radar can detect obstacles such as other vehicles, but in order to accurately perform tracking control and collision avoidance control, it is necessary to know how each vehicle's behavior changes with high accuracy. There is.

  For example, Patent Document 1 discloses that a communication baseband signal is up-converted and transmitted from an in-vehicle radar antenna, and received from the in-vehicle radar antenna and separated from the down-converted signal using the radar transmission signal. Is described.

  Patent Document 2 describes that the frequency of a radar transmission signal is changed to a frequency not used by the radar of another vehicle using road traffic communication to prevent interference with the radar device of the other vehicle. .

Patent Document 3 describes that information on surrounding vehicles is acquired by a camera, a radar, and a communication processing unit, and an avoidance measure is determined by predicting that the surrounding vehicles deviate from normal running. .
JP 11-331065 A JP 2000-304851 A JP 2005-115484 A

  In order to know how each vehicle's behavior changes when performing follow-up control and collision avoidance control, a method for exchanging information between vehicles by inter-vehicle communication has been studied. In the case where there is, a relatively long time is required to specify the partner (position for the follow-up control or collision avoidance control) whose position information is to be exchanged. For this reason, there is a problem that inter-vehicle communication is practically impossible especially when it is necessary to perform control in a short time such as collision avoidance.

  Further, the inter-vehicle communication system using the radar of Patent Document 1 has a problem that radar waves may interfere with each other and communication may not be performed accurately.

  The present invention has been made in view of the above points, and it is possible to exchange information between vehicles without requiring time to specify a communication partner and eliminating the influence of radar wave interference. An object is to provide a vehicle-to-vehicle communication device.

The inter-vehicle communication device of the present invention includes timing adjustment means for transmitting a radar wave to the radar device of the own vehicle at a timing according to the satellite time information received from the satellite of the positioning system,
Position information of the other vehicle from a beat between a radar wave transmitted from the radar device of the other vehicle at a timing according to the satellite time information and a radar wave transmitted from the radar device of the own vehicle at a timing according to the satellite time information. Detecting means for detecting
When the other vehicle is present within a predetermined range from the own vehicle based on the position information of the other vehicle, transmission means for transmitting communication information on the radar wave;
By having receiving means for separating and extracting communication information from the radar wave received from the other vehicle, it does not take time to identify the communication partner, and the information between vehicles without the influence of radar wave interference. Can be exchanged.

In the inter-vehicle communication device,
The radar wave comprises a non-frequency modulation period in which frequency modulation is not performed between a frequency modulation period and a frequency modulation period in which a frequency increase period and a frequency decrease period are repeated,
The transmission means can put the communication information in the non-frequency modulation period of the radar wave.

In the inter-vehicle communication device,
When the other vehicle is within a predetermined range from the host vehicle, it can have a mode switching means for switching between a synchronous mode for operating the timing adjustment means and an asynchronous mode for stopping the timing adjustment means.

  According to the present invention, it is possible to exchange information between vehicles without requiring time to specify a communication partner and eliminating the influence of radar wave interference.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a block diagram of an embodiment of an inter-vehicle communication device of the present invention. In the figure, a vehicle control ECU (electronic control unit) 11 performs tracking control and collision avoidance control of the vehicle 10. The radar device 12 is an FMCW (Frequency Modulated Continuous Wave) radar that uses, for example, an array antenna and can determine the reception direction of radio waves, and detects obstacles in front of or in front of and behind the vehicle. The vehicle control ECU 11 is notified of the direction, distance, and relative speed of the obstacle. The radar apparatus 12 is supplied with satellite time information of a positioning system received by a GPS (Global Positioning System) receiver 13, and is also supplied with own vehicle control information such as acceleration / deceleration and steering from the vehicle control ECU 11. A radar wave modulated by the own vehicle control information is transmitted in synchronization with the satellite time information.

  The vehicle 20 performs mutual communication between the vehicle 10 and vehicle control information. The vehicle control ECU 21 performs tracking control and collision avoidance control of the vehicle 20. The radar device 22 is an FMCW radar that uses, for example, a millimeter wave or a laser that has an array antenna and can determine the direction of arrival of radio waves, detects obstacles in front of or in front of and behind the vehicle, and detects the direction of the detected obstacle, The distance and relative speed are notified to the vehicle control ECU 21. The radar device 22 is supplied with the satellite time information of the positioning system received by the GPS receiver 23 and is also supplied with own vehicle control information such as acceleration / deceleration and steering from the vehicle control ECU 21. The radar wave modulated by is transmitted in synchronization with the satellite time information.

  FIG. 2 shows a block diagram of an embodiment of the radar devices 12 and 22. In the figure, an oscillator 31 generates a transmission signal obtained by frequency-modulating (FM) a continuous wave (CW), and this transmission signal is transmitted from a transmission antenna 32.

The element antennas 33 _{1 to} 33n constitute a reception array antenna, and the signals received by the element antennas 33 _{1 to} 33n are mixed with the transmission signals by the mixers 34 _{1 to} 34n to be converted into beat signals to be FFT (Fast Fourier Transform). ) 35 ₁ to 35 n, digitized, and then frequency-analyzed. Thereafter, the signal is synthesized by the synthesis circuit 36 and supplied to the radar signal analysis circuit 37. The radar signal analysis circuit 37 analyzes the position (direction, distance, relative speed) of the obstacle or the control target vehicle. This analysis result is notified to the vehicle control ECU.

  The control circuit 38 controls the entire radar apparatus, is supplied with satellite time information from a GPS receiver, switches between synchronous mode and asynchronous mode, timing of frequency modulation period and non-frequency modulation period in synchronous mode, non-frequency The oscillator 31 is instructed to insert communication data during the modulation period. The communication circuit 39 supplies communication data supplied from the outside to the control circuit 38 in order to insert the communication data into the non-frequency modulation period and transmit it to another vehicle. Further, the communication circuit 39 is supplied with an output signal of the FFT 35n, extracts communication data transmitted from the other vehicle from this signal, and notifies the vehicle control ECU.

  FIG. 3 is a diagram for explaining the follow-up control. In the figure, the vehicle 10 communicates with the preceding vehicle 20 within a predetermined distance (for example, several tens of meters) from the host vehicle by using the radar devices 12 and 22 to accelerate, decelerate, steer, etc. of the vehicle 20. Vehicle control information is obtained in real time, and the steering is followed by narrowing the distance between vehicles. In the case of performing the follow-up control, the radar device 22 of the preceding vehicle 20 needs to be able to detect an obstacle behind the vehicle 20.

  FIG. 4 is a diagram for explaining the collision avoidance control. In the figure, a vehicle 10 communicates with a vehicle 20 facing each other within a predetermined distance (for example, several tens of meters) by using radar devices 12 and 22 so that vehicle control information such as mutual acceleration / deceleration, steering, etc. The vehicle 10 and 20 both steer in the left direction, for example, to avoid collision.

  Here, the radar apparatus 12 using a millimeter wave or a laser may cause mutual interference when the same kind of radar apparatus 22 exists nearby. However, if the same type of radar devices 12 and 22 that are present in the vicinity perform transmission at the same timing in synchronization, the position of the partner radar device that is present in the vicinity can be detected as a beat signal. If the satellite time information obtained by the GPS receivers 13 and 23 is used, the radar devices 12 and 22 can synchronize accurately with an error of 10 nsec or less.

  The following describes the tracking control or collision avoidance control. The radar waves output from the radar devices 12 and 22 are composed of a frequency modulation period in which a frequency increase period and a frequency decrease period are repeated, and a non-frequency modulation period in which no frequency modulation is performed between the frequency modulation periods. Thus, the frequency modulation period and the non-frequency modulation period have the same timing.

  In the radar device 12, the radar wave output from the radar device 12 of the vehicle 10 is shown by a solid line Ia in FIG. 5A, and the radar wave output from the radar device 22 of the vehicle 20 is a broken line in FIG. As indicated by Ib (the vertical axis is the frequency difference), the distance between the vehicles 10 and 20 and the relative speed are obtained from this beat signal.

  Further, in the radar device 22, the radar wave output from the radar device 22 of the vehicle 20 is shown by a solid line IIa in FIG. 5B, and the radar wave output from the radar device 12 of the vehicle 10 is shown in FIG. The beat signal of both radar waves becomes as shown by the solid line IIc in FIG. 5B, and the distance and relative speed between the vehicles 10 and 20 are obtained from this beat signal.

  When inter-vehicle communication is performed using the radar devices 12 and 22, communication data is placed in a non-frequency modulation period. In the radar apparatus 12, as shown by a solid line IIIa in FIG. 6A, for example, eight frequency peaks are formed at the timing at which the non-frequency modulation period is equally divided, and the first, third and fourth frequency peaks P1, P3 and P4 do not change the timing when the non-frequency modulation period is equally divided, and the remaining second, fifth, sixth, seventh and eighth frequency peaks P2, P5, P6, P7 and P8 indicate the non-frequency modulation period. From the equally divided timing, the phase difference between the radar wave of the radar device 12 detected by the radar device 12 and the radar wave of the radar device 22 is advanced (early) and transmitted.

  Here, communication data in which the frequency peaks P1, P3, and P4 that have not been advanced in phase are associated with the value 1, for example, and the frequency peaks P2, P5, P6, P7, and P8 in which the remaining phases are advanced are associated with the value 0. Send.

  In the radar apparatus 22, as shown by a solid line IVa in FIG. 6B, for example, eight frequency peaks are formed at a timing at which the non-frequency modulation period is equally divided. In the radar device 22, the radar wave output from the radar device 12 of the vehicle 10 is shown by a broken line IVb in FIG. 6B, and the beat signal of both radar waves is shown by a solid line IVc in FIG. 6B. Become.

  That is, the frequency peaks P2, P5, P6, P7, and P8 whose phase has been advanced by the radar apparatus 12 are not generated because the phase difference from the corresponding frequency peak of the radar apparatus 22 is eliminated. The frequency peaks P 1, P 3, P 4 that are not advanced generate beats with the corresponding frequency peaks of the radar device 22. For example, 8-bit communication data can be transmitted and received depending on whether or not a frequency peak occurs during the non-frequency modulation period. Note that the communication data is not limited to 8 bits.

  FIG. 7 shows a flowchart of the inter-vehicle communication process executed by the radar devices 12 and 22 in the synchronous mode. In the figure, in step S11, the timings of the frequency modulation period and the non-frequency modulation period are determined using the satellite time information obtained by the GPS receivers 13 and 23.

  Next, frequency analysis of the radar wave received in step S12 is performed by FFT to separate the reflected wave of the radar wave transmitted from the own apparatus and the beat signal of the radar wave transmitted from the radar apparatus of the other vehicle. In step S13, the position (direction, distance, relative speed) of the radar device of the other vehicle is calculated from the beat signal as shown in FIG.

  Next, whether or not the vehicle on which the radar device of the other vehicle is mounted in step S14 is within a predetermined distance for performing the follow-up control as shown in FIG. 3 or within a predetermined distance for performing the collision avoidance control as shown in FIG. Determine whether or not.

  If the other vehicle is present within a predetermined distance for performing the follow-up control or the collision avoidance control, vehicle control information such as acceleration / deceleration, steering, etc. of the own vehicle is placed in the non-frequency modulation period of the radar wave in step S15. Send. In step S16, communication data of vehicle control information such as acceleration / deceleration, steering, etc. of the other vehicle transmitted from the counterpart vehicle in the non-frequency modulation period of the radar wave is received. In step S17, the vehicle control ECU is notified of the vehicle control information of the other vehicle. Accordingly, the vehicle control ECU performs the follow-up control or the collision avoidance control of the own vehicle in consideration of the vehicle control information of the other vehicle, and the process proceeds to step S14.

  On the other hand, if the other vehicle does not exist within the predetermined distance for performing the follow-up control or the collision avoidance control in step S14, the process proceeds to step S11.

  FIG. 8 shows a flowchart of the mode switching process executed by the radar devices 12 and 22. In the figure, in step S21, the radar apparatus enters the asynchronous mode, and detects an obstacle near the host vehicle without synchronizing with the satellite time information.

  In step S22, it is determined whether or not there is interference with the radar wave of the other vehicle. If there is no interference with the radar wave of the other vehicle, the process proceeds to step S21. If there is interference with the radar wave of another vehicle, the mode is changed to the synchronous mode in step S23, the timing of the frequency modulation period and the non-frequency modulation period is determined using the satellite time information obtained by the GPS receiver, Detect nearby obstacles.

  Next, in step S24, it is determined whether or not the fixed time T1 has elapsed. When the fixed time T1 (for example, several milliseconds to several seconds) has elapsed, the mode is shifted to the asynchronous mode in step S25 without being synchronized with the satellite time information. Detect obstacles near your vehicle. Further, in step S26, it is determined whether or not a certain time T2 (for example, several milliseconds to several seconds) has elapsed. When the certain time T2 has elapsed, the process proceeds to step S22.

  In this way, it is possible to exchange information between vehicles without taking time to identify a communication partner and without the influence of radar wave interference, thereby enabling tracking control or collision avoidance control. Can be performed with high accuracy.

  In addition, the synchronous mode for performing the follow-up control or the collision avoidance control and the asynchronous mode for detecting the obstacle in the vicinity of the own vehicle can be alternately switched to separate the opponent vehicle and the obstacle in the follow-up control or the collision avoidance control. .

  It should be noted that step S11 corresponds to the timing adjusting means described in claims, step S13 corresponds to the detecting means, step S15 corresponds to the transmitting means, step S16 corresponds to the receiving means, and steps S23 to S26 are the mode switching. Corresponds to means.

It is a block diagram of one embodiment of the inter-vehicle communication device of the present invention. It is a block diagram of one embodiment of a radar device. It is a figure for demonstrating tracking control. It is a figure for demonstrating collision avoidance control. It is a figure which shows a radar waveform and a beat waveform. It is a figure which shows a radar waveform and a beat waveform. It is a flowchart of the vehicle-to-vehicle communication process performed in synchronous mode. It is a flowchart of a mode switching process.

Explanation of symbols

10 vehicle 11 vehicle control ECU
12 Radar device 13 GPS receiver 20 Vehicle 21 Vehicle control ECU
22 radar device 23 GPS receiver 31 oscillator 32 transmit antennas 33 ₁ ~33n element antenna 34 ₁ to 34N mixer 35 ₁ ~35n FFT
36 Synthesis Circuit 37 Radar Signal Analysis Circuit 38 Control Circuit 39 Communication Circuit

Claims (3)

Timing adjustment means for transmitting a radar wave to the radar device of the own vehicle at a timing according to the satellite time information received from the satellite of the positioning system;
Position information of the other vehicle from a beat between a radar wave transmitted from the radar device of the other vehicle at a timing according to the satellite time information and a radar wave transmitted from the radar device of the own vehicle at a timing according to the satellite time information. Detecting means for detecting
When the other vehicle is present within a predetermined range from the own vehicle based on the position information of the other vehicle, transmission means for transmitting communication information on the radar wave;
A vehicle-to-vehicle communication device comprising receiving means for separating and extracting communication information from a radar wave received from the other vehicle. The inter-vehicle communication device according to claim 1,
The radar wave comprises a non-frequency modulation period in which frequency modulation is not performed between a frequency modulation period and a frequency modulation period in which a frequency increase period and a frequency decrease period are repeated,
The vehicle-to-vehicle communication device according to claim 1, wherein the transmission unit places the communication information in the non-frequency modulation period of the radar wave. The inter-vehicle communication device according to claim 2,
An inter-vehicle communication device comprising: a mode switching unit that switches between a synchronous mode in which the timing adjusting unit is operated and an asynchronous mode in which the timing adjusting unit is stopped when the other vehicle is within a predetermined range from the own vehicle. .

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