JP4603910B2 - Inter-vehicle communication system and radio communication apparatus - Google Patents

Description

  The present invention relates to wireless communication between vehicles, and more particularly to a wireless communication technique suitable for use in a road traffic system.

  In recent years, with the development of IT technology, road traffic systems and information communication systems are linked so that vehicles such as automobiles traveling on the road reflect information from other vehicles and the ground in their own driving. On the other hand, it has been proposed to construct an intelligent transport system (ITS) which is an advancement of the road traffic system. In this intelligent road transportation system, each vehicle is automatically platted on an automobile-only road such as an expressway to enable automatic driving of the vehicle and reduce driver fatigue. It has been studied to improve transportation efficiency by keeping the distance between vehicles as short as possible (see, for example, Patent Document 1).

In order to realize the above automatic platooning, wireless communication between vehicles with excellent real-time characteristics and high reliability is required. As a wireless communication control method used for such inter-vehicle wireless communication, a centralized control method using a base station (polling / selecting method), and direct communication between vehicles without using a base station (so-called Point -to-Point connection).
In the centralized control method, since the base station controls the wireless communication between the vehicles, it is possible to realize highly reliable communication without causing a wireless communication collision. However, since a vehicle moves at a high speed on an automobile exclusive road or the like, a wide service area is required, the system becomes complicated, and the cost increases.
On the other hand, since the contention method does not require a base station, a vehicle-to-vehicle communication system can be constructed at a relatively low cost. Therefore, in recent years, a wireless communication device that performs wireless communication based on the contention method is installed in each vehicle, and within the wireless communication area of each wireless communication device, the vehicles existing in that area (between wireless communication devices) are mutually connected. Studies are being made to make it possible to realize automatic platooning by building a system for wireless communication.
JP 2001-283372 A

However, in the contention system, since each vehicle (wireless communication device) transmits a wireless signal for transmission / reception operation independently of each other, the number of vehicles existing in the wireless communication area increases. However, there is a problem that a communication time delay due to a radio signal collision or a radio signal collision occurs.
In addition, in order to realize high-reliability inter-vehicle wireless communication with excellent real-time characteristics, when there are a plurality of vehicles, that is, a plurality of wireless communication devices, each vehicle has a right to wireless communication fairly. It is important to avoid the collision of radio signals between vehicles. Conventionally, however, radio signals collide or disappear due to fading, multipath, hidden terminal problems, etc., leading to delays in communication information and deterioration in communication quality.

  The present invention has been made in view of the above-described circumstances, and prevents wireless signal collision when wireless communication devices mounted on each of a plurality of vehicles directly communicate with each other without using a base station or the like. It is an object of the present invention to provide an inter-vehicle communication system and a wireless communication device that can be used.

To achieve the above object, the present invention is mounted on the vehicle, the radio communication apparatus for transmitting and receiving signals between Dede chromatography data with the wireless communication device mounted on another vehicle platoon, the vehicle the current position acquired from the vehicle position detecting means, the transmitted configured to be able to transmit data including the current position to the other of the wireless communication device, when transmitting the transmission data, other said wireless communications from the device, when receiving the transmission data including the current position of the other vehicle to which the other of said wireless communication device is mounted, according to the relative distance between the other vehicle and the host vehicle, the relative distance When the standby time is set so that the larger the value is, the larger the value is, and the transmission data is not received from the other wireless communication apparatus during the period from the timing when the transmission data is received until the standby time elapses. Is When該待machine time has elapsed, sends the transmission data, when receiving the transmission data from another of said radio communication device during the period, characterized by resetting the waiting time.

Further, in the above invention, when the forward traveling direction the other vehicle exists, when receiving the transmission data including the current position of the other vehicle from another of said radio communication device, the other vehicle When the vehicle is located behind the host vehicle in the traveling direction, at least the transmission data is received from the other wireless communication device mounted on the other vehicle existing ahead in the traveling direction, and the set waiting time has elapsed. In the meantime, transmission of the transmission data is prohibited.

Further, in the above invention, when the other vehicle both in progress forward does not exist, and transmits the transmission data at a predetermined radio transmission cycle.

  The present invention is also characterized in that, in the above invention, the predetermined radio transmission period is at least about 1 second or less.

Further, in the above invention, the vehicle is, when merging into a vehicle group that platoon, together with the current position of the vehicle, transmits the transmission data including the merging information indicating that merging It is characterized by that.

Further, in the above invention, the vehicle is, when separated from the vehicle group that platoon, together with the current position of the vehicle, transmits the transmission data including the separation information indicating which separates It is characterized by that.

  Moreover, the present invention is characterized in that, in the above-mentioned invention, the vehicle position detecting means is a car navigation device including a GPS or a sensor capable of acquiring position information.

In order to achieve the above object, the present invention provides a vehicle-to-vehicle communication system that includes a plurality of vehicles equipped with wireless communication devices and transmits and receives data between the wireless communication devices. Each of them acquires the current position of the host vehicle on which the host device is mounted from the host vehicle position detecting means mounted on the host vehicle, so that transmission data including the current position can be transmitted to other wireless communication devices. When each of the wireless communication devices is configured to transmit the transmission data, the wireless communication device receives transmission data including the current position of another vehicle on which the other wireless communication device is mounted from the other wireless communication device. The waiting time is set so that the larger the relative distance is, the larger the relative distance between the other vehicle and the host vehicle is, and the timing at which the transmission data is received is set. If the transmission data is not received from the other wireless communication device during the period from the time until the standby time elapses, the transmission data is transmitted when the standby time elapses, and the other data is transmitted during the period. When transmission data is received from a wireless communication device, the waiting time is reset .

  According to the present invention, the time corresponding to the relative distance between the other vehicle and the host vehicle has elapsed from the timing at which the wireless communication device received the transmission data including the current position of the other vehicle from the other wireless communication device. Since the transmission data is sometimes transmitted, the transmission timing can be made different among a plurality of wireless communication devices, and each wireless communication device directly communicates with each other without using a base station or the like. In addition, it is possible to prevent collision of radio signals.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing a configuration of an inter-vehicle communication system 1 according to the present embodiment. This inter-vehicle communication system 1 is a communication system for realizing platooning by automatic driving control of a vehicle, and as shown in the figure, a plurality of vehicles 2-1, 2-2. When there is no need to distinguish between the two, it is referred to as a vehicle 2), and each vehicle 2 is equipped with a wireless communication device 11 and a vehicle control device 12. In the inter-vehicle communication system 1, each vehicle 2 travels in a row while maintaining a substantially constant inter-vehicle distance L (for example, 10M).

  Each of the wireless communication devices 11 mounted on each vehicle 2 has wireless communication areas A-1, A-2, ... (hereinafter, each wireless communication area that has a predetermined radius centered on its own device). When there is no wireless communication area A), a wireless communication is performed directly with another wireless communication device 11 existing in the wireless communication area A without using a base station or the like. Identification information such as an ID and an address is assigned to each wireless communication device 11 in advance, and this identification information is used to indicate a destination or a transmission source terminal during communication. For example, in the reception data processing during the wireless reception operation, when the wireless communication device 11 receives data, the data whose identification information indicated as the destination of the data matches the identification information of the own device is addressed to the own device. Process as data. At this time, the wireless communication device 11 that has received the data can determine the wireless communication device 11 that has transmitted the data by referring to the identification information indicated as the data transmission source. .

  Here, in order to realize the automatic driving control, traveling information including at least the current position, the moving direction, and the moving speed of each vehicle 2 is necessary to keep the distance between the vehicles 2 properly. In particular, as in the present embodiment, in a system in which the travel information of each vehicle 2 is not centrally managed by a base station (control station) or the like, each vehicle 2 is placed around the own vehicle along with the travel information of the own vehicle. It is necessary to grasp the traveling information of other vehicles that exist and to perform automatic driving control based on the traveling information. Therefore, the wireless communication device 11 is configured to transmit the current position of the host vehicle, the traveling direction, and the vehicle speed together with the identification information to the other wireless communication devices 11. Specifically, the vehicle control device 12 acquires travel information (current position, moving direction and moving speed) of the vehicle 2 from various vehicle-side devices such as a car navigation device using a vehicle speed detection sensor or GPS, This travel information is transmitted from the wireless communication device 11 to the wireless communication device 11 mounted on another vehicle 2.

FIG. 2 is a block diagram illustrating a functional configuration of the wireless communication device 11.
As shown in this figure, the wireless communication device 11 includes a CPU 101, a memory 102, a data link unit 103, a modem unit 104, an RF unit 105, and an antenna 106.
The CPU 101 controls each unit of the wireless communication device 11. The vehicle 2 is equipped with vehicle-side devices such as various sensors and a car navigation device as its own vehicle position detection means, and travel information of the vehicle 2 acquired from the vehicle-side device is transmitted via an interface (not shown). The memory 102 input to the CPU 101 stores various programs executed by the CPU 101, data, variables, and the like, and serves as a communication buffer that temporarily stores travel information of the own vehicle 2 during wireless communication operation. Also works.

The data link unit 103 processes transmission / reception data based on a predetermined wireless communication protocol. Specifically, when the data link unit 103 receives data to be transmitted from the CPU 101, the data link unit 103 generates transmission data compliant with the wireless communication protocol and outputs the transmission data to the modulation / demodulation unit 104. When data is received, the received data is processed in accordance with the wireless communication protocol and output to the CPU 101.
The modulation / demodulation unit 104 modulates / demodulates transmission / reception data based on a predetermined wireless communication method such as a spread spectrum wireless communication method. The data modulation unit 104 modulates transmission data received from the data link unit 103 and transmits the data to the RF unit 105. When receiving data, the received data received from the RF unit 105 is demodulated and output to the data link unit 103.

  An RF (Radio Frequency) unit 105 processes a radio signal transmitted / received via an antenna based on the predetermined radio communication method, and at the time of data transmission, the transmission data received from the modem unit 104 is converted into a radio communication frequency. A radio signal is generated by being superimposed on a band carrier wave and output to the antenna 106. Thereby, the radio wave including the transmission data is transmitted from the antenna 106 to the outside. At the time of data reception, the RF unit 105 receives a radio signal received by the antenna 106, separates a carrier wave, generates reception data, and outputs the received data to the modem unit 104. As described above, the received data is processed by the modem unit 104 and the data link unit 103, and for example, traveling information of the other vehicle 2 is output to the CPU 101.

Here, in the present embodiment, the collision of radio signals is prevented by using the current position of each vehicle 2 among the current position, moving direction, and moving speed of the vehicle 2 included in the travel information.
In other words, in the present embodiment, each vehicle 2 wirelessly transmits in a fixed order, for example, wireless transmission is performed in order from the leading vehicle 2 to the succeeding vehicle 2 between the vehicles 2 performing the platooning. Is going to do. Thus, since each vehicle 2 transmits by radio | wireless in order, generation | occurrence | production of the collision of a radio signal can be avoided. In the following description, as a case where each vehicle 2 wirelessly transmits in a certain order, one vehicle is wirelessly transmitted in order from the leading vehicle 2 in the traveling direction to the following vehicle 2 among the plurality of vehicles 2 traveling in the platoon. Explain the case.

FIG. 3 is a diagram showing the transmission timing during the wireless transmission operation. As shown in this figure, in a wireless transmission period T from when a certain vehicle 2 performs wireless transmission until the next vehicle 2 (wireless communication device 11) performs wireless transmission, a wireless communication period TA and a wireless communication pause A period TB and a radio channel monitoring period TC are provided, and a radio transmission frame (transmission data) 300 is transmitted from the vehicle 2 (radio communication apparatus 11) that performs radio transmission in the radio communication period TA among these periods. .
The wireless transmission frame 300 stores traveling information including the current position of the vehicle 2. By transmitting the wireless transmission frame 300, traveling information of the host vehicle 2 is notified to other nearby vehicles 2. It has become so.

The configuration of the wireless transmission frame 300 will be described in detail. The wireless transmission frame 300 is roughly divided into a wireless header section 301 and a wireless data section 302, and the wireless header section 301 includes a wireless header 300A. The data unit 302 includes a transmission source ID 300B, a transmission vehicle position 300C, and a wireless tailor 300X.
The wireless header section 301 stores header information that conforms to the wireless communication method used in the inter-vehicle communication system 1, and this header information is stored in the wireless header 300A.

The wireless data unit 302 stores various data such as identification information of the transmission source vehicle 2 and travel information including the current position. The identification information of the transmission source wireless communication device 11 (vehicle 2) is stored in the transmission source. It is stored in the ID 300B, and the current position information is stored in the transmitting vehicle position 300C. As the current position information, for example, a coordinate value expressed by latitude and longitude, a value calculated by a magnetic nail embedded in a traveling road, or the like can be used.
The wireless tailor 300X is a frame check sequence (FCS) for the wireless communication device 11 that has received the wireless transmission frame 300 to detect an error (error) in the received wireless transmission frame 300. Data for CRC (Cyclic Redundancy Check) is stored. Further, the wireless header portion 301 and the wireless data portion 302 are identified based on the data stored in the wireless tailor 300X.
Note that a configuration may be adopted in which dedicated information for identifying the wireless header portion 301 and the wireless data portion 302 is added to the wireless transmission frame 300.
In addition to the above information, travel information such as vehicle speed and moving direction is stored in the wireless data unit 302, and these travel information is transmitted to the surrounding other vehicle 2.

The wireless communication suspension period TB is a period for another vehicle 2 (wireless communication apparatus 11) to receive and process the wireless transmission frame 300 transmitted in the wireless communication period TA. A fixed value is used for the time length of the wireless communication suspension period TB in the entire inter-vehicle communication system 1, and it is necessary for the receiving operation including the processing capability of each wireless communication device 11 (various processing such as decoding processing of received data). A time length considering time is set.
The radio channel monitoring period TC is a period provided to avoid a collision of the radio transmission frames 300 transmitted by each vehicle 2 (radio communication apparatus 11). In the radio channel monitoring period TC, radio communication is performed. For example, the device 11 performs carrier sense to determine whether or not the wireless channel is in use, and if it is in use, the wireless transmission operation is prohibited (stopped).

Here, the time length of the wireless channel monitoring period TC is not a fixed time length in each vehicle 2, but the relative distance between the vehicle 2 that transmitted the wireless transmission frame 300 in the wireless transmission period T and each vehicle 2 It is designed to be longer depending on the situation. Accordingly, the start timing t3 of the next wireless communication period TA comes from the vehicle 2 with the shortest relative distance between the vehicles, and the transmission operation of the wireless transmission frame 300 is performed. Transmission operation is prohibited.
In this embodiment, the data link unit 103 of the wireless communication apparatus 11 performs such determination of the time length of the wireless channel monitoring period TC and determination of the wireless transmission timing Ts (start timing of the wireless communication period TA). It is said.

FIG. 4 is a block diagram showing a functional configuration for determining the radio channel monitoring period TC and the radio transmission timing Ts among the functional configurations of the data link unit 103.
As shown in this figure, the data link unit 103 includes a position information processing unit 401, a counter arrival value calculation unit 402, a wireless data unit detection unit 403, a counter unit 404, an FCS determination unit 405, and a comparison determination unit. 406.
The position information processing unit 401 receives the received wireless transmission frame 300 and the position information of the own vehicle 2, and receives the position information of the transmission source vehicle 2 stored in the transmission vehicle position 300 </ b> C of the wireless transmission frame 300, The relative distance between the vehicles is calculated from the position information of the vehicle 2 and is output to the counter arrival value calculation unit 402. At this time, the position information processing unit 401 adds a positive sign to the relative distance when the transmission source vehicle 2 is located in front of the host vehicle 2, and adds a negative sign to the relative distance when located at the rear. Thus, it is possible to determine whether the transmission source vehicle 2 is located before or after the host vehicle 2.

  The counter arrival calculation unit 402 determines a radio channel monitoring period TC having a time length proportional to the relative information between the vehicles calculated by the position information processing unit 401, and the radio channel monitoring period TC and a predetermined time length. The wireless transmission timing Ts is calculated based on the wireless communication suspension period TB and the end timing t1 (see FIG. 3) of the wireless communication period TA, and is output to the comparison determination unit 406.

  The wireless data part detection unit 403 detects the start and end of the wireless data part 302 of the received wireless transmission frame 300. In addition, when the start of the wireless data unit 302 is detected, the wireless data unit detection unit 403 outputs a count stop signal to the counter unit 404, and when the end of the wireless data unit 302 is detected, A count start signal is output to the counter unit 404.

The counter unit 404 is a counter for counting the respective timings of the wireless communication suspension period TB and the wireless channel monitoring period TC based on a clock signal of a clock circuit (not shown) built in the wireless communication apparatus 11.
More specifically, when the count start signal is input from the wireless data unit detection unit 403, the counter unit 404 clears the counter value, counts up the counter from the initial value, and starts counting. . Thereby, the count starts from the end timing of the wireless data unit 302, that is, the end timing t1 of the wireless communication period TA.
The counter unit 404 counts up the counter when a count stop signal is input from the wireless data unit detection unit 403 or when a wireless transmission start signal is input from the comparison determination unit 406 described later. Stop. Therefore, the counter unit 404 starts the counting operation from the end timing t1 of the wireless communication period TA and next receives the wireless transmission frame 300 transmitted by another wireless communication device 11, or the own device transmits the wireless transmission frame. When the transmission of 300 is started, the counting operation is stopped.

The FCS determination unit 405 performs error determination on the received wireless transmission frame 300 and outputs a determination result to the comparison determination unit 406.
The comparison determination unit 406 detects the arrival of the radio transmission timing Ts by comparing the time until the radio transmission timing Ts output from the counter arrival calculation unit 402 and the counter value of the counter unit 404, for example, the CPU 101 or the like. A radio transmission start signal is output to each unit that controls radio transmission.
At this time, if the determination result of the FCS determination unit 405 determines that the received wireless transmission frame 300 has an error, the comparison determination unit 406 stops the detection processing of the wireless transmission timing Ts. This prevents the start of wireless transmission based on the wireless transmission frame 300 including an error.

Here, the counter arrival calculation unit 402 outputs a comparison determination stop value when a negative sign is given to the relative distance between the vehicles received from the position information processing unit 401. Thereby, based on reception of the wireless transmission frame 300 transmitted from the vehicle 2 behind the host vehicle 2, the wireless communication device 11 of the host vehicle 2 is prevented from starting wireless transmission.
Further, as described above, since the radio channel monitoring period TC becomes longer in proportion to the relative distance between the vehicles, the radio of the vehicle 2 that has transmitted the radio transmission frame 300 first and the vehicle 2 immediately after the shortest relative distance. The communication device 11 precedes the other vehicle 2 and the start timing t3 of the next wireless communication period TA arrives, and the wireless transmission operation is started. At this time, in the wireless communication device 11 of the other vehicle 2, the new wireless transmission frame 300 is received and the counting operation of the counter unit 404 is stopped, so that the wireless transmission of the own device is stopped. Hereinafter, the operation at this time will be described in more detail with reference to FIG.

  FIG. 5 is a diagram illustrating the operation timing of the wireless communication device 11 mounted on each of the four vehicles 2-1 to 2-4 (see FIG. 1) traveling in a row. In this figure, the wireless transmission frame 300 transmitted from the second vehicle 2-2 from the top of the four vehicles 2-1 to 2-4 traveling in a row is shown as the vehicle 2-2. The case where the other vehicles 2-1, 2-3, 2-4 existing in the wireless communication area A-2 of FIG. Moreover, in order to distinguish the radio | wireless transmission frame 300 which each vehicle 2-1 to 2-4 transmits, it shall attach | subject the code | symbol 300A-300D to each.

As described above, the wireless transmission frames 300 </ b> A to 300 </ b> D store travel information such as the moving speed and the traveling direction along with the position information of the transmission source vehicle 2. And based on these driving | running | working information, while each vehicle 2 performs automatic driving | operation control for platooning, each radio | wireless communication apparatus 11 performs radio | wireless transmission operation | movement according to said procedure.
That is, when the wireless communication devices 11 of the other vehicles 2-1, 2-3, 2-4 receive the wireless transmission frame 300B from the second vehicle 2-2 from the top, the respective wireless communication devices 11 The count of the radio transmission timing Ts is started. At this time, in the wireless communication device 11 of the leading vehicle 2-1 located in front of the second vehicle 2-2, since the relative distance to the second vehicle 2-2 is a negative sign, The wireless transmission is stopped without counting the transmission timing Ts.

  Further, since each of the vehicles 2-1 to 2-4 travels in a row with a certain inter-vehicle distance L, the wireless channel monitoring period TC set by the wireless communication device 11 of the third vehicle 2-3 from the head is set. The time length is about half of the time length of the radio channel monitoring period TC set by the radio communication device 11 of the last vehicle 2-4. In this way, the time length of the radio channel monitoring period TC differs between the third vehicle 2-3 and the last vehicle 2-4, and the third vehicle 2 than the last vehicle 2-4. -3 wireless communication device 11 first reaches the wireless transmission timing Ts, and starts transmitting the wireless transmission frame 300C.

At this time, since the last vehicle 2-4 is within the wireless channel monitoring period TC, the wireless transmission timing Ts is recalculated again with the wireless transmission of the third vehicle 2-3. If wireless transmission is not performed from another wireless communication device 11 by the recalculated wireless transmission timing Ts, transmission of the wireless transmission frame 300D is started at the wireless transmission timing Ts.
Thus, if the above procedure is used, wireless communication can be realized without causing a wireless signal collision during wireless transmission.

Next, an operation procedure when the leading vehicle 2-1 of the group of vehicles traveling in a row, that is, the vehicle 2 in which no other vehicle 2 exists in the traveling direction starts radio transmission will be described.
In general, each vehicle 2 that travels in a row requires wireless transmission of travel information of the host vehicle 2 at regular time intervals in order to avoid accidents such as a collision of the vehicle 2. When determining this fixed time interval, the distance between vehicles and the traveling speed (moving speed) during traveling are important parameters.

According to Ichiro Emori's “New Edition Car Accident Engineering” (issued by Technical Shoin in May 1993), the braking distance of a general vehicle is calculated as follows.
Braking distance Y = V ² / (2 × g × μ)
Where V: travel speed (km / hour), Y: braking distance (m), g: gravitational acceleration (9.8 m / s ² ), μ: friction coefficient.
The friction coefficient μ is a coefficient according to the road surface condition, μ = 0.70 for dry asphalt, μ = 0.45 to 0.60 for wet asphalt, and μ = 0 for concrete. .50, μ = 0.55 for gravel roads, μ = 0.15 for solid snow roads, and μ = 0.07 for ice.
Therefore, assuming that μ = 0.7 when the vehicle traveling speed V is 50 km / hour, the braking distance Y is 14 m, and when the vehicle traveling speed V is 80 km / hour, μ = 0.7. Assuming that the braking distance Y is 36 m.

  Therefore, when the traveling vehicle 2 detects the stopped vehicle 2 ahead, in order to stop without colliding with the stopped vehicle 2, for example, the traveling speed V of the traveling vehicle 2 is 50 km / hour (13.8 m / second). In this case, it is necessary to perform deceleration control from the stopped vehicle 2 to 14 m or more before. In other words, in order to realize the platooning with the traveling speed V of 50 km / hour (13.8 m / second), it means that the traveling vehicle 2 needs to detect the stopped vehicle 2 before 14 m or more. All the vehicles 2 need to notify the other vehicles 2 in the vicinity of the position information of the own vehicle 2 in a cycle of about 1 second. Actually, in consideration of a delay time and a safety factor caused by various processes such as a vehicle position calculation process, a wireless communication process, and a vehicle control, a period of 1 second or less such as a period of several hundred milliseconds is considered appropriate.

  Therefore, in the present embodiment, in the leading vehicle 2-1 (see FIG. 1) traveling in a platoon, the wireless transmission frame is set at, for example, 100 milliseconds as the wireless transmission cycle W (the time length of the wireless transmission period T shown in FIG. 3). 300 is transmitted, and the data link unit 103 manages the wireless transmission cycle W.

FIG. 6 is a block diagram showing a functional configuration for managing the radio transmission cycle W among the functional configurations of the data link unit 103. As shown in this figure, the data link unit 103 includes a host vehicle transmission monitoring unit 601, a counter unit 602, and a comparison determination unit 603.
The own vehicle transmission monitoring unit 601 detects the transmission start of the wireless transmission frame 300 of the own vehicle 2 (that is, the start timing of the wireless communication period TA) and outputs a count start signal to the counter unit 602. . At this time, the own vehicle transmission monitoring unit 601 may detect the transmission start of the wireless data unit 302 of the wireless transmission frame 300.

  The counter unit 602 is a counter for counting the respective timings of the wireless communication suspension period TB and the wireless channel monitoring period TC based on a clock signal of a clock circuit (not shown) built in the wireless communication apparatus 11. When the count start signal is input from the own vehicle transmission monitoring unit 601, the counter unit 602 clears the counter value, counts up the counter from the initial value, and starts counting. Thereby, the count operation is started from the start timing of the wireless transmission of the own device.

  The comparison determination unit 603 compares the counter value of the counter unit 602 with a predetermined radio transmission cycle W (here, 100 milliseconds), detects the radio transmission timing Ts, and controls radio transmission such as the CPU 101, for example. A wireless transmission start signal is output to each unit. As a result, in the head vehicle 2 traveling in a row, the travel information of the host vehicle 2 is transmitted to other vehicles 2 at time intervals of the wireless transmission period W. In the second and third vehicles 2 from the head, the wireless transmission frame 300 transmitted by the head vehicle 2 is received, and according to the above procedure, it is relative distance from the head vehicle 2. By setting the wireless channel monitoring period TC corresponding to the wireless transmission, wireless transmission is started one by one in order.

  In the above description, the wireless transmission operation when the plurality of vehicles 2 are traveling in a row has been described. Next, the wireless transmission operation when the vehicle 2 joins or separates (leaves) from a group of vehicles that are traveling in a row. Will be described.

  First, as shown in FIG. 7, in a situation where the three vehicles 2-1 to 2-3 are traveling in a row in this order toward the traveling direction, another vehicle (hereinafter referred to as a merged vehicle) 2- The case where 5 joins in the middle of a formation is demonstrated. The merging vehicle 2-5 travels in a travel lane adjacent to the travel lane on which the vehicles 2-1 to 2-3 travel, and is positioned between the vehicle 2-2 and the vehicle 2-3 in the traveling direction. Is moving. At this time, the wireless communication device 11 mounted on the joining vehicle 2-5 starts monitoring (receiving) the wireless communication of each of the wireless communication devices 11 of the vehicles 2-1 to 2-3 traveling in the platoon. A radio channel monitoring period TC corresponding to the transmitted relative distance to the vehicle 2 is generated to determine the radio transmission timing Ts, and preparation for starting radio communication is performed.

  For example, in the case of the situation shown in FIG. 7, the relative distance between the vehicle 2-5 and the vehicle 2-2 is shorter than the relative distance between the vehicle 2-3 and the vehicle 2-2. 2-5 starts wireless transmission before vehicle 2-3 after vehicle 2-2 completes wireless transmission. In the wireless transmission frame 300 transmitted by the vehicle 2-5, merge information indicating that the vehicle 2-5 is merged is stored, and the vehicle 2-3 positioned behind the vehicle 2-5 is The merge information is received, and automatic operation control for merge is performed. Specifically, when receiving the merge information, the vehicle 2-3 decelerates the vehicle 2-3 to provide an inter-vehicle distance that allows the vehicle 2-5 to merge as shown in FIG. The joining vehicle 2-5 has an inter-vehicle distance at which the own vehicle 2-5 can join the platoon based on the positional information of the vehicles 2-2 and 2-3 transmitted by the vehicles 2-2 and 2-3. After confirming that there is, join the formation as shown in FIG.

As described above, even when the vehicle 2-5 joins the vehicle groups 2-1 to 2-3 traveling in the platoon, the wireless channel monitoring period TC corresponding to the relative distance to the vehicle 2 wirelessly transmitted is generated. In order to determine the radio transmission timing Ts and prepare for the start of radio transmission, it is possible to perform radio transmission from the vehicle 2-5 to the vehicle groups 2-1 to 2-3 without collision of radio transmission signals. Become.
Further, the vehicle 2-5 to be joined transmits the wireless transmission frame 300 storing the join information, so that the vehicle 2-5 joins the vehicle 2-3 traveling behind the vehicle 2-5. Is notified, and it becomes possible to secure the inter-vehicle distance for merging.

Next, as shown in FIG. 10, in a situation where the four vehicles 2-1 to 2-4 are traveling in a row in this order toward the traveling direction, The case of separation (withdrawal) from the platoon to the adjacent driving lane will be described.
Between the vehicles 2-1 to 2-4 traveling in a platoon, the wireless transmission frame 300 is transmitted one by one from the leading vehicle 2-1 in the traveling direction. At this time, the vehicle 2-3 stores separation information indicating separation from the vehicle group in the wireless transmission frame 300 and transmits the separated information. Then, this separation information is received by the vehicles 2-2 and 2-4 before and after the vehicle 2-3.
Thereafter, the vehicle 2-3 moves to the adjacent traveling lane as shown in FIG. At this time, the vehicle 2-3 continues to perform wireless communication as a platoon, and continues wireless transmission in an order corresponding to the order of the platoon.

  Next, after the vehicle 2-3 has moved to the adjacent lane, the order of wireless transmission has come to notify the surrounding vehicles 2-1, 2-2, 2-4 that it has been separated from the platooning. At this time, information indicating that the separation operation from the vehicle group has been completed is stored in the wireless transmission frame 300 and transmitted, and thereafter, wireless transmission with this platoon, that is, the vehicle 2-2 traveling ahead is transmitted. The wireless transmission operation based on the reception of the wireless transmission frame 300 is stopped. Further, the vehicles 2-2 and 2-4 in the formation receive information indicating the completion of the separation operation of the vehicle 2-3, so that the vehicle 2-4 has a vehicle 2-2 as shown in FIG. The operation to increase the distance between the vehicle and the vehicle.

As described above, even when the vehicle 2-3 is separated from the group of vehicles 2-1 to 2-4 traveling in the platoon, the wireless channel monitoring period TC corresponding to the relative distance from the vehicle 2 that has wirelessly transmitted is generated. In order to determine the radio transmission timing Ts and prepare for the start of radio transmission, it is possible to perform radio transmission from the vehicle 2-3 to the vehicle groups 2-1 to 2-4 without collision of radio transmission signals. Become.
Further, the vehicle 2-3 to be separated transmits the wireless transmission frame 300 in which the separation information is stored, so that the vehicle 2-3 is separated from the vehicle 2-4 traveling behind the vehicle 2-3. Can be notified.

  As described above, according to the present embodiment, when the wireless communication device 11 transmits the wireless transmission frame (transmission data) 300, the wireless communication device 11 wirelessly includes the current position of the other vehicle 2 from the other wireless communication device 11. When the transmission frame 300 is received, a wireless channel monitoring period TC having a time length corresponding to the relative distance between the other vehicle 2 and the host vehicle 2 is set, and the wireless channel monitoring period TC is wireless when the wireless channel monitoring period TC elapses. Since the transmission frame 300 is configured to be transmitted, the transmission timings can be made different among the plurality of wireless communication apparatuses 11, and each wireless communication apparatus 11 directly performs wireless communication with each other without using a base station or the like. In addition, it is possible to prevent collision of radio signals.

  In particular, when each of the wireless communication devices 11 receives a new wireless transmission frame 300 before the wireless channel monitoring period TC elapses, when the new wireless transmission frame 300 is received, the new wireless transmission frame 300 Since the radio channel monitoring period TC having a time length corresponding to the relative distance between the vehicle 2 that transmitted the frame 300 and the host vehicle 2 is newly set, it is possible to reliably avoid collision of radio signals. In addition, it is possible to prevent a situation in which the specific wireless communication device 11 cannot always transmit.

  Further, according to the present embodiment, when each of the wireless communication devices 11 receives the wireless transmission frame 300 including the current position of the other vehicle 2 from the other wireless communication device 11, the other vehicle 2 When the vehicle is located behind the traveling direction, the transmission of the wireless transmission frame 300 is prohibited. Therefore, an opportunity for wireless transmission is given one by one in order from the leading vehicle 2 along the traveling direction.

  Further, according to the present embodiment, the wireless communication device 11 is configured to transmit the wireless transmission frame 300 at a predetermined wireless transmission cycle W when there is no other vehicle 2 ahead in the traveling direction. The wireless communication between the vehicles 2 can be repeated cyclically, and the traveling information between the vehicles 2 can be intermittently received.

  Further, according to the present embodiment, the wireless communication device 11 joins together with the current position of the own vehicle 2 when the own vehicle 2 on which the own device is mounted joins a group of vehicles traveling in a row. Since the wireless transmission frame 300 including the merge information indicating the effect is transmitted, the other vehicle 2 traveling behind the vehicle 2 is notified of the merge, and the inter-vehicle distance for the merge is ensured. Is possible.

Further, according to the present embodiment, the wireless communication device 11 separates together with the current position of the own vehicle 2 when the own vehicle 2 on which the own device is mounted is separated from the group of vehicles traveling in the platoon. Since the wireless transmission frame 300 including the separation information indicating the fact is transmitted, the other vehicle 2 traveling behind the vehicle 2 is promptly notified that the vehicle 2 is separated.
As described above, according to the present embodiment, the formation of the formation can be rearranged only with the position information of the vehicle, and wireless communication can be performed in accordance with the order of the vehicles 2 when traveling in the formation without collision of wireless signals. It becomes.

The above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified and applied within the scope of the present invention.
For example, in the above-described embodiment, when an abnormality such as a failure occurs in the vehicle 2, the wireless communication device 11 stores information indicating that in the wireless transmission frame 300 and transmits the information. It is possible to transmit the situation in the traveling direction (for example, a broken vehicle) to the succeeding vehicle 2 in a bucket relay manner.

It is a figure which shows the structure of the communication system between vehicles which concerns on embodiment of this invention. It is a block diagram which shows the functional structure of a radio | wireless communication apparatus. It is a timing chart which shows the transmission timing with the structure of a radio | wireless transmission frame. It is a block diagram which shows the functional structure of a data link part. It is a timing chart which shows the transmission operation | movement of a radio | wireless transmission frame. It is a block diagram which shows the functional structure of a data link part. It is a figure for demonstrating operation | movement when a vehicle joins the vehicle group which is running in platoon. It is a figure for demonstrating operation | movement when a vehicle joins the vehicle group which is running in platoon. It is a figure for demonstrating operation | movement when a vehicle joins the vehicle group which is running in platoon. It is a figure for demonstrating operation | movement when a vehicle isolate | separates from the vehicle group which is running in platoon. It is a figure for demonstrating operation | movement when a vehicle isolate | separates from the vehicle group which is running in platoon. It is a figure for demonstrating operation | movement when a vehicle isolate | separates from the vehicle group which is running in platoon.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inter-vehicle communication system 2 Vehicle 11 Wireless communication apparatus 12 Vehicle control apparatus 103 Data link part 300 Radio transmission frame A Wireless communication area L Inter-vehicle distance T Radio transmission period TA Radio communication period TB Radio communication suspension period TC Radio channel monitoring period Ts Radio Transmission timing

Claims (8)

Is mounted on the vehicle, the radio communication apparatus for transmitting and receiving signals between Dede chromatography data with the wireless communication device mounted on another vehicle platoon,
Wherein the current position of the vehicle, acquired from the vehicle position detecting means is configured to transmit data including the current position to be transmitted to another of said radio communication device,
When transmitting the transmission data,
From another of said radio communication device, upon receiving the transmission data including the current position of the other vehicle to which the other of said radio communication apparatus is mounted, according to the relative distance between the other vehicle and the own vehicle Then, after setting the standby time so that the larger the relative distance is, the larger the value is, the transmission data is transmitted from the other wireless communication device during the period from the timing when the transmission data is received until the standby time elapses. If not received , the transmission data is transmitted when the standby time has elapsed, and if the transmission data is received from another wireless communication device during the period, the standby time is reset. A wireless communication device . If the direction of travel the other vehicle is present, when the other of the wireless communication device receives the transmission data including the current position of the other vehicle, the position in the traveling direction rearward from the other vehicle is the vehicle In the case where the transmission data is transmitted, the transmission data is received at least until the set standby time elapses after receiving transmission data from the other wireless communication device mounted on the other vehicle existing in the forward direction. The wireless communication apparatus according to claim 1, wherein the wireless communication apparatus is prohibited. If the other vehicle both in the progress forward is not present, the wireless communication apparatus according to claim 1 or 2, characterized in that transmitting the transmission data at a predetermined radio transmission cycle. The wireless communication apparatus according to claim 3 , wherein the predetermined wireless transmission period is at least about 1 second or less. The own vehicle, when merging into a vehicle group that platoon, together with the current position of the vehicle, according to claim 1, wherein the transmitting the transmission data including the merging information indicating that merging The wireless communication device according to any one of the above. The own vehicle, when separated from the vehicle group that platoon, the together with the current position of the vehicle, according to claim 1, wherein the transmitting the transmission data including the separation information indicating which separates The wireless communication device according to any one of the above. The wireless communication device according to any one of claims 1 to 6 , wherein the vehicle position detection unit is a car navigation device including a GPS or a sensor capable of acquiring position information. In a vehicle-to-vehicle communication system that includes a plurality of vehicles equipped with wireless communication devices and transmits and receives data between the wireless communication devices.
Each of the wireless communication devices acquires a current position of the host vehicle on which the host device is mounted from a host vehicle position detection unit mounted on the host vehicle, and transmits transmission data including the current position to another wireless communication. Configured to transmit to the device,
Each of the wireless communication devices
When transmitting the transmission data,
When receiving transmission data including the current position of another vehicle on which the other wireless communication device is mounted from the other wireless communication device, according to the relative distance between the other vehicle and the host vehicle, After setting the standby time so that the larger the relative distance is, the larger the value is, the reception data is received from the other wireless communication device during the period from the timing when the transmission data is received until the standby time elapses. If not, the transmission data is transmitted when the standby time has elapsed, and when the transmission data is received from the other wireless communication device during the period, the standby time is reset. Inter-vehicle communication system .

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