JP2010187136A - Communication control program, communication control apparatus, and navigation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication control program which can control transmission power optimally in the inter-vehicle communication. <P>SOLUTION: A control unit 50 includes a location information and speed information acquisition unit 521 which acquires the location information and speed information of a vehicle, and the location information and speed information of surrounding vehicles; a velocity vector calculation unit 523 which calculates the velocity vectors of the vehicle and the surrounding vehicles based on the location information and speed information thus acquired; a communication object vehicle specification unit 524, which specifies the surrounding vehicle closest to the vehicle in front of the vehicle in the travelling direction thereof and the surrounding vehicle closest to own vehicle in the rear of the vehicle in the travelling direction thereof from among the surrounding vehicles, in the same direction within a predetermined range and having the orientation of velocity vector identical to that of the vehicle, and specifies the surrounding vehicle farther from own vehicle out of the specified surrounding vehicles in front and rear of the vehicle as the communication object vehicle, and a transmission power determination unit 525 which determines the transmission power for use in the inter-vehicle communication based on the distance between the specified surrounding vehicle of farther distance and the vehicle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication control program, a communication control device, and a navigation device.

  Conventionally, a vehicle is equipped with a communication device (a device controlled and operated by a communication control program or a communication control device) and a navigation device having a communication function (hereinafter collectively referred to as a communication terminal). Yes. Attention has been focused on inter-vehicle communication technology for exchanging information between these communication terminals and supporting vehicle travel. In vehicle-to-vehicle communication, a large number of communication terminals share a wireless band, so that efficient use of the band is desired. Sending information over a wider range than necessary leads to wasted radio bandwidth. Moreover, unnecessary transmission of information to a wide area also interferes with necessary communication.

  As a vehicle-to-vehicle communication technology, for example, a technology has been proposed in which a relative distance after a predetermined time elapses from a communication terminal is predicted, and transmission power of wireless communication is controlled based on a predicted value of the relative distance (for example, patent document). 1). In addition, a technique for reducing transmission power according to an increase in the number of communication terminals serving as communication partners has been proposed (see, for example, Patent Document 2).

JP 2007-6395 A Special table 2008-507883 gazette

  However, the technique described above does not disclose a technique for selecting which communication terminal is the target of wireless communication when there are a plurality of communication terminals capable of communication. Therefore, it is not intended to control the transmission power by clarifying to which communication terminal the radio wave can reach. For this reason, there is a problem that wireless communication is performed with more power than necessary.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a communication control program, a communication control device, and a navigation device that can optimally control transmission power in inter-vehicle communication.

  The communication control program disclosed in this specification is a communication control program for a communication device that is mounted on a mobile body and can be used for vehicle-to-vehicle communication. The computer acquires position information and speed information of the communication device. And the step of acquiring the position information and speed information of the other communication device from the other communication device, and based on the acquired position information and speed information, the own communication device and the other communication device. A step of calculating a speed vector indicating a moving direction and a speed with respect to the communication device, and a direction of the speed vector among other communication devices having the same direction as the direction of the speed vector of the own communication device within a predetermined range A step of identifying a first communication device closest to the front of the moving body mounted with the communication device and a second communication device closest to the rear of the moving body of the moving device; Location information of the local communication device and Based on the positional information of the first communication device and the second communication device, the communication device having the farthest distance from the own communication device among the first communication device and the second communication device. And a step of determining transmission power to be used for vehicle-to-vehicle communication based on the distance between the communication device having the longer specified distance and the own communication device.

  According to the disclosure of the present specification, it is possible to optimally control transmission power in inter-vehicle communication.

It is a block diagram which shows the structure of a navigation apparatus. It is a block diagram which shows the structure of a control part. It is a figure which shows the structure of a software functional block. It is a figure for demonstrating the method to identify the vehicle which the advancing direction is the same direction as the own vehicle. (A) shows a case where a surrounding vehicle exists in the communicable range ahead and behind the host vehicle, and (B) shows a case where a surrounding vehicle exists in the communicable range ahead of the host vehicle, (C) shows a case where a surrounding vehicle exists in the communicable range behind the host vehicle, and (D) shows a case where no surrounding vehicle exists in the communicable range ahead and behind the host vehicle. It is. It is a figure which shows an example of the table which sets transmission power. It is a flowchart which shows the process sequence of a control part, and is a flowchart which shows the procedure until the process which excludes the vehicle which cannot specify the advancing direction from the candidate of an object vehicle. It is a flowchart which shows the process sequence of a control part, and is a flowchart which shows the process sequence after setting a target vehicle and setting transmission power. It is a figure for demonstrating the method to detect the surrounding vehicle which exists ahead and back of the own vehicle.

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

An embodiment in which the present invention is applied to a navigation device mounted on a vehicle (moving body) will be described. The navigation device 1 according to the present embodiment has a communication function for performing wireless communication with a communication terminal such as a communication device or a navigation device mounted on another vehicle. Specifically, as shown in FIG. 1, the navigation device 1 includes a radio communication antenna 10, a radio communication unit 20, a GPS (Global Positioning System) signal receiving antenna 30, and a GPS information receiving unit 40. A control unit 50, a storage unit 60, a display 70, a speaker 80, and an operation unit 90.
In the following description, an object that communicates with the navigation device 1 will be described as a vehicle, but in reality, a communication terminal mounted on the vehicle is an object.

The antenna 10 is an antenna for wireless communication, and is a communication terminal of a vehicle (hereinafter referred to as a surrounding vehicle) existing around the host vehicle on which the navigation device 1 is mounted, or a communication device ( Hereinafter, information is transmitted and received by wireless communication with a roadside communication device. The roadside communication device includes a broadcasting device such as a radio beacon, an optical beacon, and FM broadcasting, and a communication device equipped with DSRC (Dedicated Short Range Communication).
The wireless communication unit 20 modulates the signal received from the control unit 50 in accordance with an instruction from the control unit 50 and transmits the modulated signal to the destination communication terminal or roadside communication device via the antenna 10. In addition, the radio communication unit 20 demodulates a signal received via the antenna 10 and outputs the demodulated signal to the control unit 50.

  The GPS information receiving unit 40 receives a GPS signal transmitted from a GPS satellite via the antenna 30. The GPS signal received by the GPS information receiving unit 40 is output to the control unit 50 and used to identify at least one of the current position and speed of the host vehicle on which the navigation device 1 is mounted.

The control unit 50 determines at least one of the current position and speed of the host vehicle based on the GPS signal received by the GPS information receiving unit 40, the position information acquired from the roadside communication device, the map data stored in the storage unit 60, and the like. Identify. In addition, the control unit 50 calculates a guide route to the destination input from the operation unit 90 and superimposes the guide route information on the map data read from the storage unit 60 and displays the information on the display 70.
In addition, the control unit 50 performs wireless communication with the surrounding vehicle and the roadside communication device during traveling to acquire position information and speed information of the surrounding vehicle. For example, the roadside communication device performs wireless communication with surrounding vehicles and collects position information and speed information of the surrounding vehicles. The roadside communication apparatus notifies the collected information to each surrounding vehicle. The control unit 50 displays the acquired position and speed of the surrounding vehicle on the display 70 or outputs sound from the speaker 80 to notify the driver. The driver can recognize the position of the surrounding vehicle by referring to the display 70 or listening to the voice guidance, and can drive the vehicle. Details of the processing of the control unit 50 will be described later.

  The storage unit 60 stores map data for navigation. The storage unit 60 reads out the corresponding map data according to the control of the control unit 50 and outputs it to the control unit 50. Further, the map data stored in the storage unit 60 can be rewritten under the control of the control unit 50.

  The display 70 is a display device that displays information, and displays information in which navigation guidance routes are superimposed on map data in accordance with the control of the control unit 50.

  The operation unit 90 is an operation information input unit for a user (passenger of a vehicle), and inputs a navigation destination, route setting information, and the like. Information input through the operation unit 90 is output to the control unit 50.

  Next, the control unit 50 will be described with reference to FIG. FIG. 2 shows hardware included in the control unit 50. The control unit 50 includes a ROM (Read Only Memory) 51, a CPU (Central Processing Unit) 52, a RAM (Random Access Memory) 53, an input / output interface 54, a graphic interface 55, and an audio conversion unit 56.

  In the ROM 51, a program for controlling the CPU 52 is recorded. The CPU 52 reads a program recorded in the ROM 51 and performs a calculation according to the read program. A functional block realized by cooperation of hardware such as the CPU 52 and a program stored in the ROM 51 will be described later with reference to FIG. In addition, data in the middle of computation by the CPU 52 and data after computation are recorded in the RAM 53. For example, position information, speed information, and the like of the host vehicle and surrounding vehicles are recorded.

  The input / output interface 54 is a signal input / output unit. The input / output interface 54 receives a GPS signal received by the GPS information receiver 40, operation information input by the operation unit 90, speed information measured by the vehicle speed sensor 2 mounted on the vehicle, and the like. The input / output interface 54 inputs these information and outputs them to the CPU 52. Further, the input / output interface 54 is connected to the storage unit 60. The input / output interface 54 inputs data read from the storage unit 60 according to the control of the CPU 52 and outputs the data to the CPU 52. The input / output interface 54 receives the data output from the CPU 52 and outputs the data to the storage unit 60.

  The graphic interface 55 is an interface for displaying an image processed by the CPU 52 on the display 70, and converts graphic data into a waveform electrical signal for display on the display 70.

  The voice conversion unit 56 performs signal processing such as volume adjustment and sound quality adjustment on the voice signal such as voice guidance generated by the control unit 50 and outputs the result to the speaker 80.

Next, functional blocks of the control unit 50 realized by cooperation of hardware such as the CPU 52 and a program stored in the ROM 51 will be described with reference to FIG.
The control unit 50 includes a position information / speed information acquisition unit 521, a vehicle position specification unit 522, a speed vector calculation unit 523, a communication target vehicle specification unit 524, and a transmission power determination unit 525.

  The position information / speed information acquisition unit 521 acquires a GPS signal from the GPS information reception unit 40. Further, the position information / speed information acquisition unit 521 acquires the position information where the communication device is installed, the position information of the surrounding vehicles, and the speed information from a communication device such as an optical beacon, a radio beacon, a DSRC, and an FM broadcasting device. Further, the position information / speed information acquisition unit 521 acquires speed information of the host vehicle from the vehicle speed sensor 2 mounted on the host vehicle. Further, the position information / speed information acquisition unit 521 acquires map data from the storage unit 60. Note that the position information and speed information acquisition unit 521 acquires position information and speed information of the host vehicle and surrounding vehicles a plurality of times.

The vehicle position specifying unit 522 specifies the current position of the host vehicle and the current position of each surrounding vehicle based on the position information and the information acquired by the speed information acquisition unit 521.
The vehicle position specifying unit 522 specifies the current position of the host vehicle based on the GPS signal and the map data. Further, when the position information of the communication device can be acquired from a roadside communication device such as an optical beacon or a radio beacon, the position information calculated based on the GPS signal is corrected based on the position information acquired from the communication device.
Further, the vehicle position specifying unit 522 specifies the current position of each surrounding vehicle based on the position information acquired from the roadside communication device by road-to-vehicle communication. Further, the vehicle position specifying unit 522 may specify the current position of the surrounding vehicle using position information directly acquired from the surrounding vehicle by inter-vehicle communication. The vehicle position specifying unit 522 records the position information of the specified own vehicle and surrounding vehicles in the RAM 53.

The speed vector calculation unit 523 obtains speed vectors of the host vehicle and the surrounding vehicles.
First, the speed vector calculation unit 523 obtains the direction of the speed vector of the host vehicle from the position information of the host vehicle calculated by the vehicle position specifying unit 522 a plurality of times. Since the vehicle position specifying unit 522 calculates the position information of the own vehicle every predetermined time, the speed vector calculation unit 523 calculates the speed by calculating the difference in the position information of the own vehicle calculated every predetermined time. Calculate the direction of the vector. In addition, the speed indicated by the vehicle speed information (speed information) acquired from the vehicle speed sensor 2 by the position information / speed information acquisition unit 521 is the size of the speed vector. Further, the speed vector calculation unit 523 obtains the direction and magnitude of the speed vector of each surrounding vehicle in the same manner as the host vehicle. The velocity vector may be determined based on the GPS signal.

The communication target vehicle specifying unit 524 specifies a vehicle that is a target for setting transmission power of inter-vehicle communication.
First, the communication target vehicle specifying unit 524 determines whether there is a surrounding vehicle in which the traveling direction of the vehicle is in the same direction as the own vehicle based on the speed vector of the own vehicle and the speed vector of each surrounding vehicle. . The communication target vehicle specifying unit 524 calculates an angle formed by the speed vector of the host vehicle and the speed vector of the surrounding vehicle, and detects a surrounding vehicle in which the calculated angle is smaller than 10 °, for example. The processing of the communication target vehicle specifying unit 524 will be specifically described with reference to FIG. FIG. 4 shows the position information (O (X0, Y0)) and speed vector v0 (vector quantity) of the host vehicle, and the position information Pk (Xk, Yk) and speed vector vk (vector quantity) of the surrounding vehicle. . Note that k is a variable for specifying the surrounding vehicle, and is an arbitrary natural number.
The communication target vehicle specifying unit 524 calculates the following equation (1) for each surrounding vehicle whose speed vector is calculated by the speed vector calculating unit 523, and there is a surrounding vehicle in which the traveling direction of the vehicle is in the same direction as the own vehicle. It is determined whether or not to do. If the direction of the velocity vector can be acquired as an angle from GPS information or the like, the left side of Equation (1) may be the absolute value of the angle difference.

なお、ｍ，ｎは、周辺車両を特定する変数であって、任意の自然数である（ｍ≠ｎ）。また、自車両の位置情報を（Ｏ（Ｘ0，Ｙ0））とし、周辺車両の位置情報をＰｍ（Ｘm，Ｙm）及びＰｎ（Ｘn，Ｙn）とする。さらに、周辺車両Ｐｍの速度ベクトルをｖm（ベクトル量）とし、周辺車両Ｐｎの速度ベクトルをｖn（ベクトル量）とする。式（２）を満たす周辺車両Ｐｍは、自車両よりも前方に位置することを示し、式（２）を満たす周辺車両Ｐｎは、自車両よりも後方に位置することを示す。 Next, when the communication target vehicle specifying unit 524 determines that there is a surrounding vehicle whose traveling direction is in the same direction as the own vehicle, whether there are one or more surrounding vehicles in front and rear of the own vehicle, respectively. Determine whether or not. That is, as shown in FIG. 5A, it is determined whether or not there are one or more neighboring vehicles in the communicable range in front and behind the host vehicle. When the surrounding vehicle exists only on one side of the own vehicle as shown in FIG. 5 (B) or FIG. 5 (C), or the surrounding vehicle is located both before and after the own vehicle as shown in FIG. 5 (D). If it does not exist, it is removed from the target.
The communication target vehicle specifying unit 524 calculates Equation (2) below for surrounding vehicles whose traveling direction is in the same direction as the host vehicle, and determines whether there is a surrounding vehicle that satisfies Equation (2).

Note that m and n are variables that specify surrounding vehicles, and are arbitrary natural numbers (m ≠ n). Further, the position information of the host vehicle is (O (X0, Y0)), and the position information of the surrounding vehicles is Pm (Xm, Ym) and Pn (Xn, Yn). Furthermore, the speed vector of the surrounding vehicle Pm is vm (vector amount), and the speed vector of the surrounding vehicle Pn is vn (vector amount). The surrounding vehicle Pm that satisfies the expression (2) indicates that it is positioned ahead of the host vehicle, and the surrounding vehicle Pn that satisfies the expression (2) indicates that it is positioned behind the own vehicle.

If the communication target vehicle specifying unit 524 determines that there are one or more surrounding vehicles before and after the host vehicle, the communication target vehicle specifying unit 524 specifies a surrounding vehicle closest to the host vehicle among the surrounding vehicles located in front of the host vehicle. Similarly, the communication target vehicle specifying unit 524 specifies a peripheral vehicle closest to the host vehicle among the peripheral vehicles located behind the host vehicle. Based on the position information specified by the vehicle position specifying unit 522, the communication target vehicle specifying unit 524 obtains the nearby vehicles closest to the own vehicle in front and behind the own vehicle, respectively.
Next, when the communication target vehicle specifying unit 524 obtains the nearest vehicles closest to the own vehicle in front and behind the own vehicle, the communication target vehicle specifying unit 524 specifies a peripheral vehicle far from the own vehicle. The identified surrounding vehicle is set as a target vehicle (hereinafter referred to as a turret vehicle) for setting transmission power for inter-vehicle communication.

The transmission power determination unit 525 sets transmission power used for vehicle-to-vehicle communication based on the distance between the target vehicle specified by the communication target vehicle specification unit 524 and the host vehicle. Moreover, you may perform the setting value of the transmission power after determining a target vehicle according to patent document 1 other well-known techniques.
The table shown in FIG. 6 is recorded in the RAM 53 in the control unit 50, and the transmission power determination unit 525 determines transmission power with reference to the table shown in FIG. In the table shown in FIG. 6, the attenuation amount according to the distance of the transmission power is recorded. The transmission power determining unit 525 determines the attenuation amount of the transmission power based on the distance to the target vehicle. The transmission power determination unit 525 sets a value obtained by subtracting the obtained transmission power attenuation from the maximum transmission power as the transmission power. The transmission power determined by the transmission power determination unit 525 is notified to the wireless communication unit 20 via the input / output interface 54.

In the present embodiment, as shown in FIG. 5 (A), when there are surrounding vehicles in front and rear of the host vehicle, it is determined that it is not necessary to maximize the transmission power of the inter-vehicle communication and transmit. Communication is performed with the transmission power set low. The transmission power is set by setting the surrounding vehicle farther away from the host vehicle as the target vehicle among the surrounding vehicles located in front of and behind the host vehicle, and setting the transmission power so that radio waves reach the target vehicle. .
Further, when the surrounding vehicle exists only on one side of the own vehicle as shown in FIG. 5 (B) or FIG. 5 (C), or the front and rear of the own vehicle as shown in FIG. 5 (D). When there is no surrounding vehicle in any of them, the transmission power is not limited. In this case, the control unit 50 sets the transmission power of the vehicle-to-vehicle communication to the maximum transmission power, and transmits the position information of the host vehicle to the periphery of the host vehicle. In addition, when there are surrounding vehicles before and after the own vehicle, and the distance between the surrounding vehicle far from the own vehicle and the own vehicle is longer than a predetermined distance, the control unit 50 transmits the transmission power. Is set to the maximum transmission power. When communication is performed with the transmission power set low, the range in which surrounding vehicles can receive radio waves from the host vehicle becomes narrow. For example, when a surrounding vehicle exists only in front of the host vehicle shown in FIG. 5B, the surrounding vehicle in the front can continuously receive radio waves from the host vehicle, but approaches the host vehicle from behind. The incoming neighboring vehicles cannot receive radio waves unless they approach the vehicle. Accordingly, the driver of the rear vehicle is delayed in recognition of the own vehicle.

Next, the processing procedure of the control unit 50 will be described with reference to the flowcharts shown in FIGS.
When the control unit 50 is activated when the power is turned on (step S1), first, the GPS signal transmitted from the GPS satellite and received by the GPS information receiving unit 40 is input a plurality of times (step S2). Moreover, the control part 50 inputs the vehicle speed information (speed information) of the own vehicle measured by the vehicle speed sensor 2 a plurality of times (step S2). Next, the control part 50 inputs the positional information and speed information of the surrounding vehicle which exist in the circumference | surroundings of the notification own vehicle by vehicle-to-vehicle communication or road-to-vehicle communication several times (step S3).

  Next, the control unit 50 calculates speed vectors of the host vehicle and the surrounding vehicles (step S4). First, the control unit 50 specifies the current position of the host vehicle from the GPS signals acquired a plurality of times, and obtains the direction of the speed vector of the host vehicle. That is, the control unit 50 obtains the direction of the velocity vector by obtaining the difference between the position information specified from the previously received GPS signal and the position information specified from the GPS signal received this time. As for the magnitude of the speed vector, the latest one of the speed information inputted a plurality of times becomes the magnitude of the speed vector. Similarly, the controller 50 determines the direction and magnitude of the speed vector of the surrounding vehicle. Further, the speed vector information included in the GPS signal may be used as it is without acquiring the GPS signal and the speed information a plurality of times.

  Next, the control unit 50 determines whether or not the speed of the host vehicle is 0 km / h (step S5). The control unit 50 determines that the speed is 0 km / h when the speed is 1 km / h or less. When the speed of the host vehicle is 1 km / h or less (step S5 / YES), the control unit 50 determines whether or not the previous speed vector of the host vehicle is stored in the RAM 53 (step S6). When the previous value of the speed vector is stored in the RAM 53 (step S6 / YES), the control unit 50 sets the previous value of the speed vector stored in the RAM 53 as the speed vector of the host vehicle used this time ( Step S7). The speed vector of the host vehicle used this time may be set to 1 km / h, which is a threshold for determining 0 km / h. Further, when the previous value of the speed vector of the host vehicle is not stored in the RAM 53 (step S6 / NO), the control unit 50 ends this process.

Next, the control unit 50 determines whether there is a surrounding vehicle having a speed of 0 km / h (step S8). Similarly, the control unit 50 determines that the speed is 0 km / h when the speed is 1 km / h or less. When there is no surrounding vehicle having a speed of 1 km / h or less (step S8 / NO), the control unit 50 performs processing according to the flow shown in FIG. Details of this processing will be described later.
When there is a surrounding vehicle having a speed of 1 km / h or less (step S8 / YES), the control unit 50 determines whether or not the previous value of the speed vector of the surrounding vehicle is stored in the RAM 53. (Step S9). When the previous value of the speed vector is stored in the RAM 53 (step S9 / YES), the control unit 50 uses the previous value of the speed vector stored in the RAM 53 as the speed vector of the surrounding vehicle detected in step S8. Set (step S10). The speed vector of the vehicle detected in step S8 may be set to 1 km / h, which is a threshold for determining 0 km / h. If the previous value of the speed vector is not stored in the RAM 53 (step S9 / NO), the speed vector of the surrounding vehicle detected in step S8 is set to be invalid (step S11). That is, the control unit 50 excludes surrounding vehicles whose traveling direction cannot be specified from the target vehicles for inter-vehicle communication.

  Next, processing following FIG. 7 will be described with reference to the flowchart shown in FIG. The control unit 50 determines whether there is a surrounding vehicle whose traveling direction is in the same direction as the own vehicle using the speed vector of the own vehicle and the speed vector of the surrounding vehicle (step S12). Specifically, the control unit 50 calculates the above-described equation (1) for each surrounding vehicle for which the speed vector has been calculated, and determines whether the traveling direction is in the same direction as the host vehicle.

When it is determined that there is a surrounding vehicle whose traveling direction is the same as that of the own vehicle (step S12 / YES), the control unit 50 of the surrounding vehicles whose traveling direction is the same as that of the own vehicle. It is determined whether or not there are one or more surrounding vehicles ahead and behind (step S13). The control unit 50 calculates the above-described equation (2) and determines whether or not there is a surrounding vehicle Pm in front of the own vehicle and a surrounding vehicle Pn behind the own vehicle.
When it is determined that there are one or more surrounding vehicles in front and rear of the host vehicle (step S13 / YES), the control unit 50 determines the own vehicle for each of the surrounding vehicles positioned in front and rear of the host vehicle. And the nearest vehicle is identified (step S15). The control unit 50 obtains a nearby vehicle closest to the host vehicle from the front and rear of the host vehicle from the position information of the host vehicle acquired in step S2 and the position information of the surrounding vehicle acquired in step S3.

  Next, the control unit 50 sets, as a target vehicle, a surrounding vehicle that is farther from the own vehicle among the surrounding vehicles before and after the identified own vehicle (step S16). When the target vehicle is set, the control unit 50 sets transmission power based on the set distance between the target vehicle and the host vehicle (step S17). A table shown in FIG. 6 is prepared in the RAM 53 of the control unit 50, and the control unit 50 sets transmission power with reference to the table shown in FIG. When the distance between the target vehicle and the host vehicle is longer than a predetermined distance, the control unit 50 sets the transmission power to the maximum (predetermined value). The predetermined distance in this case refers to, for example, a case where the host vehicle and the target vehicle are far away from the range recorded in the table shown in FIG. When the transmission power is set, the control unit 50 notifies the wireless communication unit 20 of the set transmission power information (step S18). Further, the control unit 50 records the set transmission power information in the RAM 53.

  If it is determined in step S12 that there is no surrounding vehicle having the same traveling direction as the host vehicle (step S12 / NO), the control unit 50 sets the transmission power to the maximum value within the specified range (step S12). S14). Similarly, in step S13, even when one or more neighboring vehicles do not exist before and after the host vehicle (step S13 / NO), the control unit 50 sets the transmission power to the maximum value within the specified range ( Step S14). When the transmission power is set, the control unit 50 notifies the wireless communication unit 20 of the set transmission power information (step S18). Further, the control unit 50 records the set transmission power information in the RAM 53.

  Moreover, the control part 50 will complete | finish this flow, if a power supply is turned off (step S1 / NO).

As described above, in this embodiment, when it is determined that there are surrounding vehicles before and after the own vehicle (that is, the own vehicle is in the train), the transmission power of the inter-vehicle communication is reduced. For this reason, information transmission is not performed with an electric power stronger than necessary, and waste of the radio band can be suppressed.
[Modification 1]

In the embodiment described above, the control unit 50 determines whether or not there is a surrounding vehicle whose traveling direction is the same as that of the own vehicle, and more than one surrounding vehicle exists in front of and behind the own vehicle. I was deciding whether to do it.
In addition to this, for example, as shown in FIG. 9, based on the current position of the host vehicle, a predetermined range of front, rear, left, and right is set as a detection area, and it is determined whether or not a surrounding vehicle exists in this detection area. Also good.
When the current position of the host vehicle is specified using a GPS signal or the like, the control unit 50 sets a detection area based on the specified current position. For example, a predetermined value is added to or subtracted from the current position, the coordinates of P, Q, R, and S that are the four corners of the detection area shown in FIG. 9 are specified, and the detection area is specified. Next, the control unit 50 specifies whether or not there is a surrounding vehicle in the detection area from the position information of the surrounding vehicle. When it is determined that the surrounding vehicle is present in the detection area, the control unit 50 determines whether or not there are one or more surrounding vehicles in front and rear of the host vehicle using the above-described equation (2). To do.
Even with such a processing method, it is possible to accurately determine whether or not there are one or more neighboring vehicles in front and behind the host vehicle.
[Modification 2]

In the embodiment described above, when there are surrounding vehicles before and after the host vehicle, the transmission power is set with the surrounding vehicle having the farther distance among the nearest surrounding vehicles before and after the target vehicle as the target vehicle.
In addition to this, when there is a surrounding vehicle before and after the own vehicle, and the distance between the own vehicle and the surrounding vehicle approaches a predetermined value (for example, 10 m) or less, wireless communication by inter-vehicle communication is performed. It may be set not to be performed. For example, when the distance between the front and rear surrounding vehicles of the host vehicle approaches a predetermined value (for example, 10 m) or less, wireless communication by inter-vehicle communication is not performed. The distance between the host vehicle and the surrounding vehicle can be changed based on the speed information of the host vehicle or the surrounding vehicle. For example, when the speed of the surrounding vehicle approaching the own vehicle becomes smaller than 30 km / h, the inter-vehicle communication is stopped when the distance between the own vehicle and the surrounding vehicle is 10 m or less. When the speed of the surrounding vehicle is 30 to 45 km / h, the inter-vehicle communication is stopped when the distance between the own vehicle and the surrounding vehicle is 30 m or less.
[Modification 3]

In addition, when there are surrounding vehicles before and after the own vehicle, and the speed of the own vehicle or the speed of the own vehicle and the surrounding vehicle both become 0 km / h due to a signal waiting at an intersection, etc. Communication may be stopped. Since the vehicle is stopped and the own vehicle is in the train, wireless communication may be stopped.
[Modification 4]

Further, in the above-described embodiment, the transmission power is set with the farther surrounding vehicle of the front and rear nearest vehicles closest to the own vehicle as the target vehicle, but the neighboring vehicle closer to the own vehicle. May be set as the target vehicle. Therefore, the position of the host vehicle can be notified to the nearby vehicle closest to the host vehicle. For this reason, transmission power can be further reduced and waste of the radio band can be suppressed.
[Modification 5]

In the above-described embodiment, when the angle between the speed vector of the own vehicle and the speed vector of the surrounding vehicle is smaller than 10 °, it is determined that the surrounding vehicle is traveling in the same direction as the own vehicle. It was. In addition to this, for example, the setting of the angle formed by the velocity vector may be changed according to the road width. The control unit 50 determines the road width of the traveling lane from the information acquired from the communication device installed on the road or the current position specified by the GPS signal and the map data stored in the storage unit 60. For example, if it is determined that the road has become three lanes, the control unit 50 changes the angle to 20 °. That is, when the angle formed by the speed vector of the host vehicle and the speed vector of the surrounding vehicle is smaller than 20 °, it is determined that the surrounding vehicle is traveling in the same direction as the host vehicle.
By performing such control, optimal control can be performed according to the road width.

  The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Navigation apparatus 2 Vehicle speed sensor 10, 30 Antenna 20 Wireless communication part 40 GPS information receiving part 50 Control part 60 Storage part 70 Display 80 Speaker 90 Operation part

Claims (6)

A communication control program for a communicator mounted on a moving body and usable for inter-vehicle communication,
On the computer,
Obtaining the position information and speed information of the communication device;
Obtaining the position information and speed information of the other communication device from another communication device;
Based on the acquired position information and the speed information, calculating respective speed vectors indicating the moving direction and speed of the local communication device and the other communication device;
Among other communication devices in which the direction of the velocity vector is in the same direction within the predetermined range as the direction of the velocity vector of the own communication device, the first direction closest to the front of the traveling body of the own mobile device equipped with the own communication device Identifying the first communication device and the second communication device closest to the rear of the moving body in the traveling direction;
Based on the position information of the communication apparatus and the position information of the first communication apparatus and the second communication apparatus, the communication apparatus out of the first communication apparatus and the second communication apparatus. Identifying a communication device that is farther away from
Determining transmission power to be used for vehicle-to-vehicle communication based on the distance between the communication device with the longer distance specified and the communication device;
Communication control program to execute.   The communication control according to claim 1, further comprising a step of setting the transmission power to a predetermined value when a distance between the local communication apparatus and the communication apparatus having a longer specified distance is longer than a predetermined distance. program.   When the first communicator and the second communicator are specified and it is determined from the acquired speed information that the moving body is in a stopped state, the step of stopping the inter-vehicle communication is performed. The communication control program according to claim 1. Determining the width of the road on which the mobile body is moving based on the location information of the communication device and the map data acquired from the storage means storing map data;
Changing the predetermined range to specify that the moving direction is the same direction based on the determined road width;
The communication control program according to claim 1. A communication control device for a communicator mounted on a moving body and usable for inter-vehicle communication,
First acquisition means for acquiring position information and speed information of the communication device;
Second acquisition means for acquiring position information and speed information of the other communication device from another communication device;
Based on the acquired position information and speed information, calculation means for calculating speed vectors indicating the moving direction and speed of the local communication device and the other communication device, respectively,
Among other communication devices in which the direction of the velocity vector is in the same direction within the predetermined range as the direction of the velocity vector of the own communication device, the first direction closest to the front of the traveling body of the own mobile device equipped with the own communication device A first specifying means for specifying the first communication device and the second communication device closest to the rear of the moving body in the traveling direction;
Based on the position information of the communication apparatus and the position information of the first communication apparatus and the second communication apparatus, the communication apparatus out of the first communication apparatus and the second communication apparatus. A second specifying means for specifying a communication device farther away from
Transmission power determining means for determining transmission power to be used for vehicle-to-vehicle communication based on the distance between the communication device whose distance is longer and the communication device,
A communication control device.   A navigation device comprising the communication control device according to claim 5.

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