JP2013161140A - Sensor device, distance measuring method and distance measuring program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply acquire congestion information.SOLUTION: A sensor device in a first vehicle includes a data reception section, a radar transmission section, a radar reception section, a calculation section and a data transmission section. The data reception section receives a measurement request for requesting the measurement of a congestion length on a first lane. The radar transmission section and the radar reception section perform transmission of a radar signal wave to a vehicle to be a transmission source of the measurement request and reception of a reflected wave of the radar signal wave. The calculation section calculates a second distance to be a distance from a starting point vehicle up to the first vehicle. The second distance is a value determined from a first distance to be a distance from the starting point vehicle notified in the measurement request up to the vehicle to be a transmission source, a distance from the vehicle to be a transmission source up to the first vehicle and the length of the first vehicle. When the data transmission section is located on the first lane and cannot communicate with a second vehicle which is a vehicle on an opposite side of the vehicle to be a transmission source in relation to the first vehicle and is located at the closest position, the data transmission section transmits the measurement request including the second distance to a third vehicle on a second lane having the same advancing direction as that of the first lane.

Description

  The present invention relates to a sensor device used for distance measurement and a distance measurement method using the sensor device.

  In order to know the situation of traffic jams on the road, a method of analyzing information measured by a traffic jam sensor installed on an expressway or a main road is used. In addition, the measurement vehicle equipped with a specific measuring instrument is run on the road that is the target of the traffic congestion status, and the traffic congestion information is obtained by analyzing the data measured while the measurement vehicle is traveling. Things are also done.

  As a related technology, a vehicle is devised that detects the state of the host vehicle and receives new traffic information generated from the received information and the information of the host vehicle when traffic information is received from another vehicle in front of the host vehicle. Has been. Here, each vehicle specifies its current position and traveling direction based on position information obtained by the Global Positioning System (GPS), and calculates information such as a traffic jam distance.

  Further, when starting the vehicle group traveling, the target vehicle is specified, information on the target vehicle is transmitted to the following vehicle by inter-vehicle communication, and each subsequent vehicle performs traveling control of the own vehicle with reference to the same target vehicle. A method has also been proposed. Furthermore, a method is also known in which information on the vehicle in front of the host vehicle in the vehicle group is acquired by inter-vehicle communication, and the acceleration of the host vehicle is controlled based on the acquired information.

JP 2007-148901 A Japanese Patent Laid-Open No. 10-162282 JP 2010-176353 A

  In the method of installing a traffic jam sensor, there is a problem that the cost of installation increases because the traffic jam sensor is increased in order to increase the accuracy of information. On the other hand, in the method of running a measurement vehicle, in order to improve accuracy, it is required to collect and edit more information, so that the burden on a system that performs measurement processing and analysis processing is large.

  With the method using the positioning result by GPS, accurate position information cannot be obtained in places where it is difficult to receive signals from GPS satellites, such as in a tunnel or an area where high-rise buildings are dense. For this reason, there is a possibility that accurate information about the traffic jam cannot be obtained depending on the environment where the traffic jam occurs. Further, in the method of acquiring traffic jam information by inter-vehicle communication, there is a case where information cannot be transmitted because a vehicle that does not support inter-vehicle communication is included in a target vehicle train for collecting traffic jam information.

  An object of the present invention is to provide a method for easily acquiring accurate traffic jam information.

  In the system according to the present embodiment, the sensor device mounted on the first vehicle includes a data reception unit, a radar transmission unit, a radar reception unit, a calculation unit, and a data transmission unit. The data receiving unit sends a measurement request for determining the length of traffic jam in the first lane starting from a starting vehicle located in the first lane in the first lane including the starting vehicle. Receive from a source vehicle that is one of the vehicles. The radar transmission unit transmits a radar signal wave toward the transmission source vehicle. The radar receiver receives a reflected wave of the radar signal wave reflected from the transmission source vehicle. The calculation unit calculates a second distance that is a distance from the starting vehicle to the first vehicle. Here, the second distance is a first distance, which is a distance from the starting vehicle to the transmission source vehicle notified by using the measurement request, from the transmission source vehicle obtained by the reflected wave. It is a value obtained using the distance to the first vehicle and the length of the first vehicle. When the first vehicle is located in the first lane, the data transmission unit is a vehicle that is present on the opposite side of the transmission source vehicle with respect to the first vehicle in the first lane. Attempts to communicate with the second vehicle located closest to the vehicle. If communication with the second vehicle fails, the data transmission unit transmits a measurement request including the second distance to a third vehicle located in the second lane that travels in the same direction as the first lane. To do.

  Accurate traffic information can be easily acquired.

It is a figure which shows the example of the method concerning embodiment. It is a figure which shows the example of a structure of a road surface sensor. It is a figure which shows the example of the hardware constitutions of a road surface sensor. It is a figure which shows the example of a structure of a vehicle-mounted sensor. It is a figure which shows the example of the hardware constitutions of a vehicle-mounted sensor. It is a figure which shows the example of measurement of traffic congestion distance. It is a figure which shows the example of a lane table. It is a figure which shows the example of the running direction of a lane. It is a figure explaining the example of the information element contained in a measurement start request message. It is a figure explaining the example of the information element contained in a measurement request message. It is a figure which shows the example of the information element contained in a measurement response message. It is a flowchart explaining the example of operation | movement of a vehicle-mounted sensor. It is a figure which shows the example of measurement of the congestion distance which concerns on 2nd Embodiment. It is a flowchart explaining the example of operation | movement of a vehicle-mounted sensor. It is a flowchart explaining the example of operation | movement of a road surface sensor. It is a figure explaining the example of the determination method of a traveling direction.

  FIG. 1 shows an example of a method according to an embodiment. It is assumed that the road shown in FIG. 1 has two lanes (lane 1, lane 2) in which the vehicle travels in the same direction. The road surface sensor 10 confirms whether a traffic jam has occurred for each of the lanes 1 and 2. In the following description, it is assumed that the lane 1 is congested.

  When the road surface sensor 10 detects the occurrence of a traffic jam, the vehicle 30 that is closest to the road surface sensor 10 among the vehicles 30 traveling in the lane where the traffic jam occurs is set as a starting vehicle. In the example of FIG. 1, the vehicle 30a that travels at the head of the lane 1 is the starting vehicle. Furthermore, the road surface sensor 10 requests the starting vehicle to measure the length of the traffic jam. Here, the length of the traffic jam is a total value of the sum of the lengths of the vehicles traveling in the lane 1 and the sum of the inter-vehicle distances between the vehicles traveling in the lane 1.

  It is assumed that the in-vehicle sensor mounted on the vehicle 30a tries to establish communication with the vehicle 30b that is a succeeding vehicle in the lane 1, but communication fails. Then, the vehicle-mounted sensor mounted on the vehicle 30a establishes communication with the vehicle-mounted sensor of the vehicle 30c traveling in the same direction as the vehicle 30a in the lane 2 that is the adjacent lane of the lane 1, and the vehicle The vehicle 30c is notified of the length (CLa) of 30a. The vehicle-mounted sensor mounted on the vehicle 30c measures an inter-vehicle distance (A) between the vehicle 30a and the vehicle 30c and an angle (α) formed by the straight line connecting the vehicle 30a and the vehicle 30c with respect to the lane 1. The length of the vehicle 30c is assumed to be CLc. Then, the vehicle-mounted sensor of the vehicle 30c calculates that the length of the traffic jam in the lane 1 is equal to or greater than CLa + Acos α + CLc.

  Next, it is assumed that the vehicle-mounted sensor of the vehicle 30c has established communication with the vehicle-mounted sensor of the vehicle 30d that is traveling in the lane 1 that is a target for determining the length of the traffic jam. The vehicle-mounted sensor of the vehicle 30c notifies that the lane 1 is a target for determining the length of the traffic jam and the calculation result obtained by the vehicle 30c.

  The vehicle-mounted sensor of the vehicle 30d measures an inter-vehicle distance (B) between the vehicle 30c and the vehicle 30d and an angle (β) formed by the straight line connecting the vehicle 30c and the vehicle 30d with respect to the lane 1. The length of the vehicle 30d is assumed to be CLd. Then, the vehicle-mounted sensor of the vehicle 30d calculates that the length of the traffic jam in the lane 1 is greater than or equal to CLa + Acos α + CLc + Bcos β + CLd. When the in-vehicle sensor of the vehicle 30d confirms that there is no following vehicle of the vehicle 30d, it determines that the length of the traffic jam is CLa + Acos α + CLc + Bcos β + CLd, and transmits the calculation result to the in-vehicle sensor of the vehicle 30c. The vehicle-mounted sensor of the vehicle 30c notifies the received result to the vehicle-mounted sensor of the vehicle 30a, and the vehicle-mounted sensor of the vehicle 30a notifies the road surface sensor 10 of the obtained result.

  Thus, according to the method according to the embodiment, each vehicle in a traffic lane in a traffic jam adds the inter-vehicle distance between the length of the host vehicle and the previous vehicle to the value notified from the previous vehicle. By notifying the succeeding vehicle, the length of the traffic jam is obtained in the last vehicle. Even if a vehicle that does not support inter-vehicle communication is included in the target vehicle train for collecting traffic jam information, the exact length of the traffic jam is calculated using vehicles in other lanes. For example, in the example of FIG. 1, the vehicle 30b does not support inter-vehicle communication, but the distance from the tail of the vehicle 30a to the head of the vehicle 30d is obtained as Acos α + CLc + Bcos β. Furthermore, since the information from the positioning satellite is not used in the method according to the embodiment, the length of the traffic jam is accurate even in a place where information from the positioning satellite cannot be received, such as in a tunnel or an area where high-rise buildings are dense. Is measured.

  FIG. 2 shows an example of the configuration of the road surface sensor 10. The road surface sensor 10 includes an antenna 11, a data transmission unit 12, a data reception unit 13, a communication unit 14, a radar transmission unit 15, a radar reception unit 16, a radar processing unit 17, and a calculation unit 18. The data transmission unit 12 can transmit data to the in-vehicle sensor mounted on the vehicle 30 traveling on the road via the antenna 11. The data receiving unit 13 receives data transmitted from the in-vehicle sensor via the antenna 11. The communication unit 14 processes the data input from the data reception unit 13 and outputs transmission data to the data transmission unit 12. In addition, the communication unit 14 outputs the received data to the calculation unit 18 as appropriate. The radar transmitter 15 transmits a signal to the vehicle 30 traveling on the road where the road surface sensor 10 is installed, and the radar receiver 16 receives the signal reflected from the vehicle 30. The radar processing unit 17 processes the reception signal received by the radar receiving unit 16 and outputs the processed signal to the calculation unit 18. Based on the data input from the radar processing unit 17, the calculation unit 18 obtains a distance to the vehicle 30, an irradiation angle when the radar is irradiated on the vehicle 30, and the like. The calculation unit 18 can specify the lane in which the vehicle 30 that reflected the signal is located from the obtained distance and angle. The method for identifying the lane will be described later. Further, the calculation unit 18 can detect the occurrence of traffic congestion in the area monitored by the road surface sensor 10 using information input from the communication unit 14 or the radar processing unit 17. The method for detecting the occurrence of traffic congestion is performed by any method including, for example, measuring the number of vehicles traveling per unit time or measuring the time taken for one vehicle to travel a certain distance. And

  FIG. 3 shows an example of the hardware configuration of the road surface sensor 10. FIG. 3 shows an example in which the road surface sensor 10 includes a millimeter wave radar, but the road surface sensor 10 may include other types of radars depending on the implementation. The road surface sensor 10 includes an antenna 11, an interface 21, a control circuit 22, a millimeter wave circuit 23, and a memory 24. The interface 21 operates as the data transmission unit 12 and the data reception unit 13. The millimeter wave circuit 23 operates as the radar transmitter 15 and the radar receiver 16. The control circuit 22 operates as the communication unit 14, the radar processing unit 17, and the calculation unit 18 by executing the program recorded in the memory 24. The memory 24 stores data obtained by the processing of the control circuit 22 and the like. The memory 24 can hold, for example, data obtained by the processing of the communication unit 14, the radar processing unit 17, and the calculation unit 18.

  FIG. 4 shows an example of the configuration of the in-vehicle sensor 40. The in-vehicle sensor 40 includes an antenna 41 (41a, 41b), a data transmitter 42 (42a, 42b), a data receiver 43 (43a, 43b), a communication unit 44, a radar transmitter 45 (45a, 45b), and a radar receiver. 46 (46a, 46b), a radar processing unit 47, and a calculation unit 48. In the following description, the in-vehicle sensor 40 includes two antennas, an antenna 41a and an antenna 41b. In addition, it is assumed that the antenna 41 a is installed in front of the vehicle 30 and the antenna 41 b is installed in the rear of the vehicle 30. The data transmission unit 42a transmits data via the antenna 41a, and the data reception unit 43a receives data via the antenna 41a. That is, the in-vehicle sensor 40 communicates with the in-vehicle sensor 40 and the road surface sensor 10 in the vehicle 30 located in front of the vehicle 30 on which the in-vehicle sensor 40 is mounted, using the antenna 41a, the data transmission unit 42a, and the data reception unit 43a. To do. The data transmission unit 42b transmits data via the antenna 41b, and the data reception unit 43b receives data via the antenna 41b. That is, the in-vehicle sensor 40 communicates with the in-vehicle sensor 40 and the road surface sensor 10 in the vehicle 30 located behind the vehicle 30 on which the in-vehicle sensor 40 is mounted, using the antenna 41b, the data transmission unit 42b, and the data reception unit 43b. To do.

  The communication unit 44 outputs transmission data to the data transmission units 42a and 42b and receives reception data from the data reception units 43a and 43b. The communication unit 44 processes the data input from the data receiving units 43a and 43b to generate transmission data. Further, the communication unit 44 outputs the obtained reception data to the calculation unit 48. In addition, the communication unit 44 acquires information such as numerical values used for transmission data from the calculation unit 48.

  The radar transmitter 45a irradiates a radar such as the vehicle 30 ahead with the radar via the antenna 41a. The radar receiver 46 a receives the reflected wave at the target via the antenna 41 a and outputs it to the radar processor 47. The radar processing unit 47 processes the received wave from the radar receiving unit 46 a and outputs the processed wave to the calculating unit 48. The radar transmitter 45b irradiates a target such as a following vehicle with radar via the antenna 41b. The radar receiver 46 b receives the reflected wave at the target via the antenna 41 b and outputs it to the radar processor 47. The radar processor 47 processes the received wave at the radar receiver 46 b and outputs the processed wave to the calculator 48.

  The calculation unit 48 obtains the distance and angle to the target based on the data input from the radar processing unit 47. Here, the distance and angle calculation method is selected from methods used in an arbitrary measurement technique using a radar. The calculation unit 48 obtains the distance and angle to the target located in front of the vehicle 30 using the received wave data received via the radar receiver 46a. Similarly, the calculation unit 48 can obtain the distance and angle to the target located behind the vehicle 30 using the data of the received wave received via the radar receiving unit 46b. In addition, the calculation part 48 shall memorize | store the length of the vehicle 30 in which the vehicle-mounted sensor 40 is mounted previously. Moreover, the calculation part 48 shall memorize | store beforehand the information for specifying a lane as a function of the distance from the vehicle-mounted sensor 40, and an angle. For example, the calculation unit 48 calculates the distance from the in-vehicle sensor 40 and the angle with respect to the target lane for a plurality of points located at the boundary between the lane in which the vehicle 30 in which the in-vehicle sensor 40 is mounted and the adjacent lane is running. , (Distance, angle), and associated information can be stored. For this reason, for example, the calculation unit 48 is mounted at the position where the distance from the in-vehicle sensor 40 is 0.5 m and the angle with the target lane is 0.2 degrees (0.5 m, 0.2 degrees). It can be determined that the vehicle 30 being in the lane is running. On the other hand, when the value of the point memorized as the boundary is (1 m, 60 degrees), the position where the distance from the vehicle-mounted sensor 40 is 2 m and the angle with the target lane is 60 degrees (2 m, 60 degrees) is adjacent. Determined to be a lane. It is assumed that the angle is a positive value in the clockwise direction, and the information includes information indicating which direction is the angle formed with respect to the target lane. For this reason, the calculation part 48 can specify whether the traveling direction lane is the right or left direction of the target lane from the angle value and the installation position of the antenna in the vehicle 30.

  FIG. 5 shows an example of the hardware configuration of the in-vehicle sensor 40. The in-vehicle sensor 40 includes an antenna 41 (41a, 41b), an interface 51 (51a, 51b), a millimeter wave circuit 52 (52a, 52b), a control circuit 53, and a memory 54. The interface 51a operates as the data transmission unit 42a and the data reception unit 43a, and the interface 51b operates as the data transmission unit 42b and the data reception unit 43b. The millimeter wave circuit 52a operates as the radar transmitter 45a and the radar receiver 46a, and the millimeter wave circuit 52b operates as the radar transmitter 45b and the radar receiver 46b. The control circuit 53 operates as the communication unit 44, the radar processing unit 47, and the calculation unit 48 by executing the program recorded in the memory 54. The memory 54 can appropriately store data used for processing of the control circuit 53. In addition, the memory 54 is appropriately used for processing in the communication unit 44, the radar processing unit 47, and the calculation unit 48. FIG. 5 shows an example of the hardware configuration. For example, the in-vehicle sensor 40 may include a radar other than the millimeter wave radar.

<First Embodiment>
FIG. 6 is a diagram illustrating an example of measuring a traffic jam distance. In the example of FIG. 6, it is assumed that vehicles 30a, 30b, 30c, 30e, and 30g are traveling on lane 1, and vehicles 30d, 30f, and 30h are traveling on lane 2. Further, of the vehicles 30a to 30h, the vehicle 30c and the vehicle 30e are not equipped with the in-vehicle sensor 40. In the drawing of FIG. 6, the alphabet at the end of the reference numeral of the in-vehicle sensor 40 is the same as the alphabet at the end of the symbol of the vehicle 30 on which the in-vehicle sensor 40 is mounted. For example, it is assumed that the in-vehicle sensor 40a is mounted on the vehicle 30a and the in-vehicle sensor 40b is mounted on the vehicle 30b.

  First, the road surface sensor 10 detects a traffic jam. Any known method can be used as a method by which the road surface sensor 10 detects a traffic jam. In the following description, as an example, when one or more of the three conditions (A) to (C) is satisfied, the calculation unit 18 in the road surface sensor 10 determines that a traffic jam has occurred. To do.

(A) The average reception level of the reflected wave of the radar irradiated on the same vehicle 30 does not change for a certain time or more.
(B) The speed of the vehicle 30 is below a predetermined threshold. Here, the calculation unit 18 compares the radar frequency fs transmitted from the radar transmission unit 15 with the frequency fr of the reflected wave from the vehicle 30 received by the radar reception unit 16. The calculation unit 18 determines that the speed of the vehicle 30 is equal to or less than a predetermined threshold when the difference in frequency between fr and fs is equal to or less than the threshold Th. Here, the calculation part 18 shall memorize | store threshold value Th previously.
(C) When the time-dependent change in the distance from the road surface sensor 10 to the vehicle 30 is observed by irradiating the same vehicle 30 with radar, the amount of change in the detected distance over a certain time is less than the variation threshold. . It is assumed that the variation threshold used in this case is also stored in advance by the calculation unit 18.

  (1) When the calculation unit 18 of the road surface sensor 10 detects a traffic jam, the calculation unit 18 determines a lane for measuring the length of the traffic jam. For example, the road surface sensor 10 specifies a starting vehicle as a starting point for measuring the length of a traffic jam, and specifies a lane in which the starting vehicle is located. Here, the road surface sensor 10 shall identify the lane in which the vehicle 30a is located using a radar. The radar transmitter 15 of the road surface sensor 10 transmits radar to the leading vehicle 30a in the traffic jam, and the radar receiver 16 receives the reflected wave. The calculation unit 18 calculates the distance and angle from the road surface sensor 10 to the vehicle 30a based on the reflected wave. The calculation part 18 shall be provided with the lane table which specifies the range of each lane beforehand. FIG. 7 shows an example of a lane table. In the lane table, the distance and angle from the road surface sensor 10 are recorded in association with the lane number. In the example of FIG. 7, when the distance from the road surface sensor 10 is L1 ± ΔL (m) and the radar irradiation angle is D1 ± ΔD degrees, the detected vehicle 30 is positioned in the lane 1. The vehicle 30a is assumed to have an irradiation angle D1 at a distance of L1 meters from the road surface sensor 10. Then, the calculation unit 18 determines that the vehicle 30a is located in the lane 1.

  Next, the road surface sensor 10 specifies the lane in which the vehicle 30 travels in the same direction as the lane for measuring the length of the traffic jam. In the example of FIG. 8, the vehicle 30 travels in the direction of the arrow A in the lane 1, and the vehicle 30 travels in the direction of the arrow B in the lane 2, so the vehicle 30 is in the same direction in the lane 1 and the lane 2. Is running on. On the other hand, in the lane 3, as indicated by an arrow C, the vehicle 30 travels on the opposite side to the lane 1. Thus, the road surface sensor 10 shall memorize | store the traveling direction of each lane beforehand. Therefore, the road surface sensor 10 can recognize that the congestion distance can be measured via the vehicle 30 existing in the lane 2 when the vehicle-mounted sensor 40 is not mounted on the vehicle 30 included in the lane 1. The road surface sensor 10 may recognize the traveling direction of each lane using a radar or the like.

(2) The road surface sensor 10 transmits a measurement start request message to the in-vehicle sensor 40a mounted on the vehicle 30a. An example of information elements included in the measurement start request message is shown in FIG. The measurement start request message includes information requesting to start measurement, an identifier of a lane to be measured, a feedback flag, and information on a lane having the same traveling direction. Hereinafter, the lane to be measured may be referred to as “target lane”. The feedback flag is a flag indicating whether the result of the measurement performed by the measurement start request message is transmitted to the transmission source. Here, feedback is performed when feedback flag = 1, and feedback is not performed when feedback flag = 0. The information on the lane with the same traveling direction is information indicating the identifier of the lane with the same traveling direction as the target lane, and the number of lanes in the left or right direction as viewed from the traveling direction of the target lane. including. For example, in the case of lane 2, it is a lane at a position advanced one lane to the left in the traveling direction of lane 1. Therefore, the information elements included in the measurement start request message transmitted to the vehicle 30a are as follows.
Measurement start request Target lane: Lane 1
Feedback flag: 1
Lanes traveling in the same direction: Lane 2, Lane 1 on the left side of the target lane

  (3) It is assumed that the data receiving unit 43a of the in-vehicle sensor 40a receives a measurement start message from the road surface sensor 10 through the antenna 41a. The data receiving unit 43 a outputs a measurement start request message to the communication unit 44. The communication unit 44 stores the content of the measurement start request message and generates a measurement request message to be transmitted to the following vehicle in the lane 1. FIG. 10 is a diagram illustrating an example of information elements included in the measurement request message. The measurement request message includes information on a measurement request, an inter-vehicle distance and angle, a transmission source vehicle length, a traffic jam distance, a target lane, a transmission source lane, a communication destination lane, and a lane having the same traveling direction.

  The measurement request is to measure the inter-vehicle distance between the transmission source vehicle and the angle formed by the target lane and the straight line connecting the transmission source vehicle and the communication destination vehicle with respect to the subsequent vehicle that has received the measurement request message. Is information requesting. The measurement result of the vehicle-mounted sensor 40 mounted on the transmission source vehicle 30 is recorded as the inter-vehicle distance and angle. Here, since the preceding vehicle of the vehicle 30a is not in the lane 1, it is assumed that the inter-vehicle distance and the angle are not recorded in the measurement request message transmitted from the vehicle 30a. The transmission source vehicle length is the length of the vehicle 30 on which the in-vehicle sensor 40 that is the transmission source of the measurement request message is mounted. The traffic jam distance is a distance from the head of the starting vehicle to the position where the rearmost position of the transmission source vehicle is projected on the target lane. The transmission source lane information is an identifier of a lane in which the vehicle 30 on which the in-vehicle sensor 40 of the transmission source is mounted is traveling. The communication destination lane information is an identifier of a lane in which the vehicle 30 that receives the measurement request message is traveling.

  The communication unit 44 of the in-vehicle sensor 40a transmits a message (communication request message) for establishing communication with the vehicle 30b behind the data transmission unit 42b via the antenna 41b. When the data reception unit 43b of the in-vehicle sensor 40a receives a message (response message) in response to the communication request message, the communication unit 44 recognizes that communication with the succeeding vehicle 30b of the vehicle 30a is possible.

Then, the communication unit 44 of the in-vehicle sensor 40a appropriately transmits the measurement result and the information stored in the calculation unit 48 from the calculation unit 48, thereby transmitting to the in-vehicle sensor 40b mounted on the vehicle 30b. Generate a measurement request message. The measurement request message generated by the in-vehicle sensor 40a includes the following information.
Measurement request Distance and angle between vehicles: None Sender vehicle length: CL1
Traffic jam distance: CL1
Target lane: Lane 1
Sender lane: Lane 1
Destination lane: Lane 1
Lanes traveling in the same direction: Lane 2, Lane 1 on the left side of the target lane

  (4) The data transmission part 42b of the vehicle-mounted sensor 40a transmits a measurement request message toward the vehicle-mounted sensor 40b.

  (5) The data receiver 43a of the in-vehicle sensor 40b receives the measurement request message from the in-vehicle sensor 40a. Then, the communication unit 44 notifies the radar processing unit 47 of the transmission source lane and the communication destination lane and requests measurement of the distance and angle to the transmission source vehicle 30. The radar processing unit 47 irradiates the radar toward the vehicle 30 located in front of the transmission source lane notified from the communication unit 44. Then, based on the received reflected wave data, the calculation unit 48 calculates a distance to the vehicle 30 located in front of the notified lane and an angle formed by a straight line connecting the vehicle and the vehicle 30b with respect to the target lane. Ask.

Here, the radar processing unit 47 transmits the radar from the radar transmission unit 45a to the vehicle 30a via the antenna 41a. The radar receiving unit 46 a receives the radar reflected wave from the vehicle 30 a via the antenna 41 a and outputs it to the radar processing unit 47. When the radar processing unit 47 outputs the obtained value to the calculation unit 48, the calculation unit 48 obtains a distance and an angle. Here, it is assumed that the distance from the vehicle 30b to the vehicle 30a is L2 meters, and the angle between the straight line connecting the vehicle 30b and the vehicle 30a and the lane 1 is 0 degree. The calculation unit 48 stores the obtained value. Further, the calculation unit 48 calculates a traffic jam distance from the starting vehicle. The traffic jam distance (L _{total, n} ) calculated for the nth vehicle is calculated from the following equation.
L _{total, n} = L _{total, n-1} + L _n + CL _n
Here, L _{total, n-1} is a traffic jam distance calculated for the (n-1) th vehicle, and is notified by a measurement request message. L _n is a length obtained by projecting the inter-vehicle distance obtained by the calculation in the calculation unit 48 in the direction of the target lane. Therefore, L _n = L _obs × cos θ _obs can be expressed. Note that L _obs is a distance obtained by calculation of the calculation unit 48, and θ _obs is an angle calculated by the calculation unit 48. Therefore, here, L _n is the length of the component in the direction parallel to the lane 1 of the vector starting from the end of the vehicle 30a and ending at the beginning of the vehicle 30b. CL _n is the length of the nth vehicle. Therefore, the congestion distance L _{total, 2} calculated by the calculation unit 48 of the in-vehicle sensor 40b is
L _{total, 2} = CL1 + L2 × cos0 + CL2 = CL1 + L2 + CL2.

  (6) The communication unit 44 of the in-vehicle sensor 40b transmits a communication request message in a direction parallel to the lane 1 from the data transmission unit 42b in order to check whether communication with the following vehicle of the vehicle 30b is possible. As described above, since the vehicle-mounted sensor 40 is not mounted on the vehicle 30c, a response message is not transmitted from the vehicle 30c. When the response message is not received within a predetermined time after transmitting the communication request message, the communication unit 44 of the in-vehicle sensor 40b determines that communication with the vehicle in the same lane has failed.

  (7) Next, the communication unit 44 of the in-vehicle sensor 40b attempts to establish communication with the vehicle 30 located in the same lane in the traveling direction. Vehicles with the same traveling direction are identified from information included in the measurement request message. Here, the communication unit 44 of the in-vehicle sensor 40b recognizes that the lane 2 is traveling in the same direction as the target lane, and tries to communicate with the vehicle 30 located in the lane 2. Here, since it is known that the lane 2 is the first lane on the left side in the traveling direction of the lane 1, the communication unit 44 changes the angle of the transmission destination of the antenna 41b by one lane. After adjusting the antenna 41b, the data transmission unit 42b transmits a communication request message. This time, it is assumed that a response message is transmitted from the in-vehicle sensor 40d to the in-vehicle sensor 40b within a predetermined time.

Then, the communication unit 44 generates a measurement request message addressed to the in-vehicle sensor 40d. The information included in the generated measurement request message is as follows.
Measurement request Distance and angle between vehicles: L2, 0 degree Transmission vehicle length: CL2
Traffic jam distance: CL1 + L2 + CL2
Target lane: Lane 1
Sender lane: Lane 1
Destination lane: Lane 2
Lanes with the same traveling direction: Lane 2 and first lane on the left side of the target lane The communication unit 44 of the in-vehicle sensor 40b transmits the generated measurement request message to the in-vehicle sensor 40d via the data transmission unit 42b.

(8) The data receiving unit 43a of the in-vehicle sensor 40d receives the measurement request message from the in-vehicle sensor 40b. Then, the radar processing unit 47 adjusts the direction of the antenna 41 a of the in-vehicle sensor 40 d so that a signal can be transmitted toward the lane 1. Thereafter, the radar transmitter 45a irradiates the radar toward the vehicle 30b, and the radar receiver 46a receives the reflected wave. The calculation unit 48 measures the distance and angle to the transmission source vehicle 30b using the information of the transmission source lane and the communication destination lane. Here, it is assumed that the distance from the vehicle 30d to the vehicle 30b is L3 meters, and the angle between the straight line connecting the vehicle 30d and the vehicle 30b and the lane 1 is α degrees. The calculation part 48 calculates | requires the traffic jam distance ( _{Ltotal, 3} ) from the origin vehicle as follows.
L _{total, 3} = CL1 + L2 + CL2 + L3 × cos α + CL3
Here, the length of the vehicle 30d is assumed to be CL3.

  (9) The communication unit 44 of the in-vehicle sensor 40d checks whether the in-vehicle sensor 40d can communicate with the following vehicle in the target lane. First, the communication unit 44 changes the setting of the antenna 41 b so that it can communicate with the following vehicle in the lane 1, and then transmits a communication request message from the data transmission unit 42. The communication request message is transmitted toward the vehicle 30e, but the vehicle-mounted sensor 40 is not mounted on the vehicle 30e. For this reason, the in-vehicle sensor 40d cannot receive a response message from the vehicle 30e, and the communication unit 44 of the in-vehicle sensor 40d determines that communication with the vehicle in the lane 1 has failed.

  (10) The communication unit 44 of the in-vehicle sensor 40d attempts to establish communication with the vehicle 30 traveling in the same lane as the vehicle 30d. After adjusting the angle at the antenna 41b, the data transmission unit 42b transmits a communication request message. Here, it is assumed that the data receiving unit 43b receives a response message transmitted from the in-vehicle sensor 40f mounted on the vehicle 30f within a predetermined time.

Then, the communication unit 44 generates a measurement request message addressed to the in-vehicle sensor 40f. The information included in the generated measurement request message is as follows.
Measurement request Distance and angle between vehicles: L3, α degrees Transmission vehicle length: CL3
Traffic jam distance: CL1 + L2 + CL2 + L3 × cosα + CL3
Target lane: Lane 1
Source lane: Lane 2
Destination lane: Lane 2
Lanes in the same traveling direction: Lane 2 and first lane on the left side of the target lane The communication unit 44 of the in-vehicle sensor 40d transmits the generated measurement request message to the in-vehicle sensor 40f via the data transmission unit 42b.

(11) When receiving the measurement request message from the in-vehicle sensor 40d, the in-vehicle sensor 40f measures the distance between the vehicle 30f and the vehicle 30d in the same manner as in the procedure (5). Further, the in-vehicle sensor 40f also obtains an angle formed by a straight line connecting the vehicle 30f and the vehicle 30d with respect to the lane 1. Here, it is assumed that the distance from the vehicle 30f to the vehicle 30d is L4 meters, and the angle formed between the straight line connecting the vehicle 30f and the vehicle 30d and the lane 1 is 0 degree. The calculation part 48 calculates | requires the traffic jam distance ( _{Ltotal, 4} ) from the origin vehicle as follows.
L _{total, 4} = CL1 + L2 + CL2 + L3 × cos α + CL3 + L4 + CL4
Here, the length of the vehicle 30f is assumed to be CL4.

  (12) The in-vehicle sensor 40f checks whether communication with the following vehicle in the target lane is possible by the same procedure as the procedure (9). With this processing, the communication request message is transmitted toward the vehicle 30g. The in-vehicle sensor 40g mounted on the vehicle 30g transmits a response message toward the in-vehicle sensor 40f. Therefore, the communication unit 44 of the in-vehicle sensor 40f determines that the communication with the vehicle in the lane 1 has succeeded.

(13) The in-vehicle sensor 40g obtains the distance between the vehicle 30g and the vehicle 30f and the angle between the straight line connecting the vehicle 30g and the vehicle 30f and the lane 1 by the same processing as that described in the procedure (8). It is done. Furthermore, the in-vehicle sensor 40g obtains a distance (L _{total, 5} ) from the head of the vehicle 30a as the starting vehicle to the tail of the vehicle 30g as a traffic jam distance.

  Next, the in-vehicle sensor 40g confirms whether it can communicate with the following vehicle in the lane 1 by transmitting a communication request message. Here, since the vehicle-mounted sensor 40g does not receive a response message, it determines that it cannot communicate with the following vehicle. Furthermore, the vehicle-mounted sensor 40g tries to start communication with the following vehicle in the lane 2 as in the procedure (7). However, as shown in FIG. 6, there is no vehicle 30 in the lane 2 behind the vehicle 30g. Therefore, the in-vehicle sensor 40g cannot receive a response message.

  The in-vehicle sensor 40g cannot establish communication with the following vehicle in the target lane, and further cannot establish communication with the following vehicle in the lane traveling in the same direction as the target lane, so the in-vehicle sensor 40g may be the tail end of the traffic jam. Judge that there is sex. Therefore, the in-vehicle sensor 40g transmits the radar to the rear of the lane 1 from the radar transmitter 45b via the antenna 41b. When the reflected wave cannot be received by the radar receiver 46b within a predetermined time from the transmission of the radar, the calculator 48 determines that there is no vehicle following the vehicle 30g in the lane 1. Further, when the radar is similarly transmitted for the lane 2 and no reflected wave is obtained, the calculation unit 48 determines that there is no following vehicle in the lane 2.

(14) The communication unit 44 of the in-vehicle sensor 40g generates a message for notifying the measurement result of the congestion distance. In the following description, a message for notifying the measurement result of the congestion distance may be referred to as a “measurement response message”. An example of the measurement response message is shown in FIG. The measurement response message includes information indicating that it is a message notifying the measurement result, and the obtained traffic jam distance, target lane, and measurement reliability information. The measurement reliability information indicates whether a vehicle following the vehicle 30 that generates the measurement response message is detected by the radar. In the case of measurement reliability information = Fixed, it is indicated that the following vehicle is not detected. On the other hand, when the following vehicle is detected, the measurement reliability information is set to “Not Fixed”. The measurement response message whose measurement reliability information is Not Fixed is generated when none of the detected succeeding vehicles support inter-vehicle communication. In the example of FIG. 6, since the vehicle following the vehicle 30g has not been found in the procedure (13), measurement reliability information = Fixed is set. An example of a measurement response message generated by the communication unit 44 of the in-vehicle sensor 40g is shown below.
Measurement response Traffic jam distance: L _{total, 5}
Target lane: Lane 1
Measurement reliability information: Fixed
Here, L _{total, 5} = CL1 + L2 + CL2 + L3 × cos α + CL3 + L4 + CL4 + L5 × cos β + CL5. L5 is the distance from the end of the vehicle 30f to the top of the vehicle 30g. β is an angle formed by a straight line connecting the vehicle 30 f and the vehicle 30 g with the lane 1. Furthermore, CL5 is the length of the vehicle 30g.

  The communication unit 44 transmits a measurement response message toward the transmission source of the measurement request message. The communication unit 44 can use the calculation result of the calculation unit 48 to transmit data to a position specified from the distance from the vehicle 30g to the vehicle 30f and the angle between the straight line connecting the vehicle 30f and the vehicle 30g and the lane 1. In addition, the antenna 41a is set. After the setting of the antenna 41a is completed, the data transmission unit 42a transmits a measurement response message via the antenna 41a.

  (15) The in-vehicle sensor 40f receives the measurement response message transmitted from the in-vehicle sensor 40g via the antenna 41b. Then, the communication unit 44 of the in-vehicle sensor 40f uses the distance and angle calculated by the calculation unit 48 to set the antenna 41a as in the procedure (14). When the setting of the antenna 41a is completed, the data transmission unit 42a of the in-vehicle sensor 40f transfers the measurement response message to the in-vehicle sensor 40d.

  (16) The vehicle-mounted sensor 40d receives the measurement response message in the same manner as the vehicle-mounted sensor 40f, and transfers it to the vehicle-mounted sensor 40b.

  (17) The in-vehicle sensor 40b also receives the measurement response message in the same procedure as the procedures (15) and (16) and transfers it to the in-vehicle sensor 40a.

  (18) The in-vehicle sensor 40a receives the measurement response message from the in-vehicle sensor 40b. The in-vehicle sensor 40a checks the value of the feedback flag of the measurement start request received in step (3). When the feedback flag = 1 is set, the in-vehicle sensor 40a transmits the received measurement response message to the road surface sensor 10 by broadcasting. The road surface sensor 10 recognizes the traffic jam distance from the measurement response message.

  FIG. 12 is a flowchart for explaining an example of the operation of the in-vehicle sensor 40. In the example of FIG. 12, before attempting communication with the subsequent vehicle 30, it is confirmed by the radar whether the vehicle 30 is behind. Also in the method described with reference to FIG. 6, as in FIG. 12, the presence or absence of the following vehicle may be confirmed before starting communication. The process for confirming the rear vehicle 30 with the radar is the same as the procedure (13) described with reference to FIG.

  When the data reception unit 43a receives a measurement start request message from the road surface sensor 10 or receives a measurement request message from the vehicle 30 ahead, the radar processing unit 47 determines whether there is a vehicle behind the target lane. (Steps S1 and S2). When the vehicle can be detected behind the target lane, the communication unit 44 confirms whether communication with the vehicle behind is possible (Yes in Step S2, Step S3). If communication with the rear vehicle is possible, the data transmission unit 42b transmits a measurement request message to the rear vehicle, and further instructs inter-vehicle communication with the rear vehicle (Yes in step S3, step S4). ).

  If communication with the rear vehicle is not possible in step S3, it is confirmed whether the vehicle can be detected behind the same lane in the lane different from the target lane (No in step S3, step S5). When a vehicle can be detected behind the lane different from the target lane, the communication unit 44 confirms whether communication with the detected vehicle is possible (Yes in step S5, step S6). If communication with the rear vehicle is possible, the data transmission unit 42b transmits a measurement request message including information notifying that the destination vehicle is in a lane different from the target lane to the rear vehicle (step) Yes in S6, step S7). On the other hand, if communication with the vehicle behind is not possible, measure the distance between the vehicle and the detected vehicle with radar, add the obtained value to the traffic jam distance, and generate a measurement response message. And transmitted to the vehicle ahead (Yes in step S6, step S8).

  In step S5, if a vehicle cannot be detected behind the lane different from the target lane, the vehicle is regarded as the last vehicle in the traffic jam, and a measurement response message is generated and transmitted to the vehicle ahead (step S5). No in S5, step S9). Furthermore, when it is determined No in step S2, the processing after step S5 is performed.

  In the above description, for the sake of simplicity, the case where the number of lanes in the same direction is two has been described as an example. However, if the number of lanes in the same direction is an arbitrary plurality, the first implementation The form can be adapted.

  In this way, accurate traffic information can be easily acquired via vehicles in adjacent lanes even if vehicles that do not support vehicle-to-vehicle communication are included in the target train for collecting traffic information. . The obtained traffic jam information is provided to prefectural police and road managers, and is also notified to surrounding drivers by the Vehicle Information and Communication System (VICS (registered trademark)).

  In addition, since the congestion distance is obtained by performing the inter-vehicle communication and the inter-vehicle distance measurement, the length of the congestion can be accurately grasped even if the number of road surface sensors 10 is small. Therefore, in the system in which this embodiment is used, the installation cost of the road surface sensor 10 can be reduced. Furthermore, according to the present embodiment, even if the road surface sensor 10 can narrow the detection range due to surrounding obstacles and the like, if the road surface sensor 10 can communicate with the starting vehicle 30, a traffic jam distance is required. There is an advantage that traffic jam information is acquired.

<Second Embodiment>
Next, a description will be given of an embodiment that is modified so as to make a measurement request to all the vehicles on which the in-vehicle sensor 40 is mounted when a plurality of subsequent vehicles on which the on-vehicle sensor 40 is mounted are detected. In this example, the in-vehicle sensor 40 is a vehicle in a lane in which the vehicle 30 in which the in-vehicle sensor 40 is mounted and a lane adjacent to the lane in which the vehicle 30 in which the in-vehicle sensor 40 is mounted are traveling. It can only be detected. For example, the triangular range shown in FIG. 13A is a range in which the vehicle 30k can sense the following vehicle. Further, the triangular range shown in FIG. 13B is a range in which the vehicle 30u can sense the following vehicle. The calculation unit 48 of the in-vehicle sensor 40 stores in advance how many lanes the detection range of the in-vehicle sensor 40 is on the left and right with respect to the lane on which the vehicle 30 on which the in-vehicle sensor 40 is mounted is running. Shall.

  FIG. 13 shows an example of measurement of a traffic jam distance according to the second embodiment. FIG. 13 shows an example in which the target lane is the lane 1 and the traveling directions of the three lanes from the lane 1 to the lane 3 are the same. FIG. 13 shows an example in which 22 vehicles 30 a to 30 p and 30 q to 30 x exist in the lane 1 to the lane 3. In the vehicle 30 shown in FIG. 13, the vehicle 30 marked with an X is not equipped with the in-vehicle sensor 40 and therefore cannot communicate between vehicles. On the other hand, it is assumed that a vehicle 30 indicated by a hatched square is equipped with an in-vehicle sensor 40 and can communicate between vehicles. For example, the vehicle 30a is equipped with the in-vehicle sensor 40, but the vehicle 30b is not equipped with the in-vehicle sensor 40.

  (21) It is assumed that the road surface sensor 10 transmits a measurement start request message to the vehicle 30a with the vehicle 30a as a starting vehicle. The measurement start request message also records that there are two lanes 2 and 3 in the same lane as the target lane. The vehicle-mounted sensor 40a mounted on the vehicle 30a detects the succeeding vehicle 30b of the lane 1 that is the target lane using a radar. Here, the detection range of the in-vehicle sensor 40a includes the left and right lanes of the lane in which the vehicle 30a is traveling. Therefore, the in-vehicle sensor 40a detects the vehicle 30 using the radar for the lane that has the same traveling direction as the target lane and is included in the detection range of the in-vehicle sensor 40a in addition to the target lane. In the example of FIG. 13, the vehicle-mounted sensor 40 a detects the lane 2 as a target of detection and detects the following vehicle 30 c in the lane 2. The detection of the vehicle 30 by the radar is performed in the same manner as in the first embodiment. The in-vehicle sensor 40a tries to communicate with the in-vehicle sensor 40 mounted on each detected vehicle. The communication establishment method is the same as the method described in the first embodiment.

  Here, it is assumed that the vehicle 30a can establish communication only with the vehicle 30c. Therefore, the in-vehicle sensor 40a transmits a measurement request message to the in-vehicle sensor 40c mounted on the vehicle 30c. The measurement request message includes information similar to the information described with reference to FIG. 10 in the first embodiment. However, the measurement request message transmitted from the vehicle-mounted sensor 40a mounted on the vehicle 30a to the vehicle-mounted sensor 40c mounted on the vehicle 30c includes information on the lane 2 and the lane 3 as the lane having the same traveling direction as the target lane. It shall be assumed.

  (22) The vehicle-mounted sensor 40 c mounted on the vehicle 30 c detects the vehicles 30 e to 30 g as the succeeding vehicle 30. The detection method of the following vehicle 30 is the same as that of the procedure (21). Here, it is assumed that the vehicle 30c can communicate only with the vehicle 30g among the detected vehicles. Then, the vehicle-mounted sensor 40c mounted on the vehicle 30c transmits a measurement request message to the vehicle-mounted sensor 40g mounted on the vehicle 30g.

  (23) It is assumed that the vehicle-mounted sensor 40g mounted on the vehicle 30g detects the vehicles 30i and 30j as the succeeding vehicle 30 and can communicate with the vehicle-mounted sensor 40 mounted on both the vehicle 30i and the vehicle 30j. Then, the vehicle-mounted sensor 40g mounted on the vehicle 30g transmits a measurement request message to the vehicle-mounted sensor 40i mounted on the vehicle 30i and the vehicle-mounted sensor 40j mounted on the vehicle 30j.

  (24) The vehicle-mounted sensor 40i mounted on the vehicle 30i detects the vehicles 30k to 30m as the following vehicle 30, and transmits a measurement request message to the vehicle 30k and the vehicle-mounted sensor 40 mounted on the vehicle 30m. Similarly, the vehicle-mounted sensor 40j mounted on the vehicle 30j detects the vehicles 30l and 30m as the following vehicle 30, and transmits a measurement request message to the vehicle-mounted sensor 40m mounted on the vehicle 30m.

(25) The vehicle-mounted sensor 40k mounted on the vehicle 30k detects the vehicles 30p and 30n as the following vehicle 30, but transmits a measurement request message because the vehicle-mounted sensor 40 is not mounted on any of the vehicles 30p and 30n. Can not. Therefore, the in-vehicle sensor 40k generates a measurement response message and transmits it to the in-vehicle sensor 40i mounted on the vehicle 30i. Information elements included in the measurement response message generated by the in-vehicle sensor 40k are as follows.
Measurement response Traffic jam distance: L _{total, 5}
Target lane: Lane 1
Measurement reliability information: Not Fixed
The measurement response message generation method is the same as that in the first embodiment.

  (26) The measurement response message generated in step (25) is transmitted to the road surface sensor 10 according to the procedure described in the first embodiment.

  (27) The measurement request message is also transmitted and received in the same manner as the procedures (22) to (24) after the vehicle 30m. That is, the in-vehicle sensor 40m mounted on the vehicle 30m detects the following vehicle 30q, and transmits a measurement request message to the in-vehicle sensor 40q mounted on the vehicle 30q. The vehicle 30q detects the vehicles 30s and 30t, and transmits a measurement request message to the in-vehicle sensor 40s mounted on the vehicle 30s. The in-vehicle sensor 40s detects the vehicles 30x, 30w, and 30u, and transmits a measurement request message to the in-vehicle sensor 40u mounted on the vehicle 30u.

(28) In the example of FIG. 13, since there is no vehicle behind the vehicle 30u, the in-vehicle sensor 40u cannot detect a vehicle following the vehicle 30u. Therefore, the in-vehicle sensor 40u generates a measurement response message. The information elements included in the measurement response message generated by the in-vehicle sensor 40u are as follows. Note that L _{total, 5} <L _{total, 8} .
Measurement response Traffic jam distance: L _{total, 8}
Target lane: Lane 1
Measurement reliability information: Fixed
The measurement response message generated by the in-vehicle sensor 40u is transmitted to the road surface sensor 10 by the procedure described in the first embodiment.

(29) The road surface sensor 10 receives the measurement response message generated by the in-vehicle sensor 40k in step (26), and receives the measurement response message generated by the in-vehicle sensor 40u in step (28). Therefore, the calculation unit 18 of the road surface sensor 10 compares the congestion distance included in the two received measurement response messages. Since L _{total, 5} <L _{total, 8} , the calculation unit 18 determines that the congestion distance included in the measurement response message generated by the in-vehicle sensor 40u is longer. Moreover, the calculation part 18 confirms that the measurement reliability information produced | generated by the vehicle-mounted sensor 40u is Fixed. Then, the calculation unit 18 determines that the congestion distance is L _{total, 8} .

  FIG. 14 is a flowchart illustrating an example of the operation of the in-vehicle sensor 40 according to the second embodiment. In the example shown in FIG. 14, variables m and M are used. The variable m is the number of vehicles to which a measurement request message including information notifying that the lane is different from the target lane is transmitted. The variable M is the number of vehicles 30 in which the in-vehicle sensor 40 successfully detects and establishes communication among the lanes having the same traveling direction as the target lane. Steps S11 to S14 in FIG. 14 are the same as steps S1 to S4 described with reference to FIG.

  If communication with a rear vehicle located in the target lane is not possible in step S13, the in-vehicle sensor 40 confirms whether the vehicle can be detected in the traveling direction or behind the same lane in a lane different from the target lane (step S13). No, step S15). At this time, the in-vehicle sensor 40 appropriately detects all subsequent vehicles included in the detection range of the in-vehicle sensor 40 by operating the radar transmitter 45b, the radar receiver 46b, the antenna 41b, and the like. If a vehicle can be detected in step S15, the communication unit 44 confirms whether communication can be established with one or more of the detected vehicles (Yes in step S15, step S16). When there is a vehicle that can establish communication, the calculation unit 48 obtains the number M of vehicles that can communicate and sets the variable m to 1 (step S17). The data transmission unit 42b transmits a measurement request message including information for notifying that the vehicle is in a lane different from the target lane to the in-vehicle sensor 40 mounted on the mth vehicle 30 among the vehicles that have established communication ( Step S18). Thereafter, the calculation unit 48 increments m by 1 and checks whether m is larger than M (steps S19 and S20). Until the variable m becomes larger than M, the processes of steps S18 to S20 are repeated.

  On the other hand, when communication with the vehicle behind is impossible, the distance between one of the detected vehicles and the host vehicle is measured by the radar. Further, the calculation unit 48 obtains the length of the component parallel to the target lane among the vectors having the end of the host vehicle as the start point and the start and end points of the following vehicle, and adds the obtained length to the congestion distance. To do. The communication unit 44 generates a measurement response message including the congestion distance calculated by the calculation unit 48 and transmits it to the vehicle ahead (No in step S16, step S21). In step S15, if a vehicle cannot be detected behind a lane different from the target lane, the vehicle is regarded as the last vehicle in a traffic jam, and a measurement response message is generated and transmitted to the vehicle ahead (step S15). No in S15, step S22). Moreover, if it determines with No by step S12, the process after step S15 will be performed.

  FIG. 15 is a flowchart for explaining an example of the operation of the road surface sensor 10. When the road surface sensor 10 detects a traffic jam, the road surface sensor 10 transmits a measurement start request message to the vehicle 30 equipped with the in-vehicle sensor 40 (step S31). Further, the communication unit 14 of the road surface sensor 10 periodically confirms whether or not the measurement response message has been received until a predetermined waiting time elapses (steps S32 to S34). When the measurement response message is received from the in-vehicle sensor 40 mounted on the starting vehicle, the communication unit 14 extracts information such as a traffic jam distance included in the measurement response message and outputs the information to the calculation unit 18. The calculation unit 18 confirms whether the traffic jam distance input from the communication unit 14 is longer than the traffic jam distance that has been notified so far (step S35). When a longer traffic distance is obtained than before, the calculation unit 18 updates the traffic distance and the measurement reliability value to the information notified by the latest measurement response message (Yes in step S35, step S36). . Furthermore, the calculation unit 18 confirms whether the measurement reliability value is Fixed (step S37). When the measurement reliability value is not “Fixed”, the road surface sensor 10 may further receive a measurement response message generated by the last vehicle 30 in the traffic jam. Therefore, the processes after Step S32 are repeated (Step S37). No). On the other hand, when the measurement reliability value is “Fixed”, the road surface sensor 10 has received the measurement response message generated by the last vehicle 30 in the traffic jam, so the calculation unit 18 determines the traffic jam distance and the measurement reliability value. After confirming, the process ends (Yes in step S37, step S38). Also, if it is determined in step S33 that the predetermined time has elapsed, the calculation unit 18 determines the congestion distance and the measurement reliability value and ends the process (Yes in step S33, step S38). . In addition, also when the measurement response message is not received within the preset time, the process in the road surface sensor 10 is complete | finished.

  As described above, in this embodiment, a measurement request is made from one vehicle to a plurality of subsequent vehicles. For this reason, as shown in FIG. 13, even when the vehicle 30 equipped with the in-vehicle sensor 40 and the vehicle 30 not equipped with the in-vehicle sensor 40 are mixed, there is a possibility that the distance of the traffic jam can be accurately obtained. It is higher than the first embodiment. For example, if a measurement request is made only from the vehicle 30g in FIG. 13 to the vehicle 30i and a measurement request is made only from the vehicle 30i to the vehicle 30k, the congestion distance is the length from the head of the vehicle 30a to the head of the vehicle 30n. End up. In the present embodiment, a measurement request is made from the vehicle 30g to both the vehicle 30i and the vehicle 30j, and a measurement request is made from the vehicle 30j to the vehicle 30m, so that the traffic jam distance is calculated from the head of the vehicle 30a to the vehicle 30u. It is the length to the end.

<Third Embodiment>
In the third embodiment, an embodiment in which the in-vehicle sensor 40 identifies a lane in which the traveling direction of the vehicle 30 is the same as the target lane will be described. The third embodiment can be applied to a case where the vehicle 30 is moving in a lane in which the traveling direction is different from the lane that is a target for measuring the congestion distance.

  The in-vehicle sensor 40 that determines a lane having the same traveling direction as the target lane transmits radar from the radar transmission unit 45b toward the following vehicle. The radar processing unit 47 notifies the calculation unit 48 of the frequency of the received radar and the frequency of the transmitted radar. The calculation unit 48 stores a threshold value in advance, and determines that the traveling direction is opposite to the target lane when the received radar frequency is significantly lower than the threshold value. The in-vehicle sensor 40 performs this process on the vehicle 30 located in various directions by changing the direction of the antenna 41b and the like, thereby determining a lane having the same traveling direction as the target lane.

  FIG. 16 illustrates an example of a method for determining the traveling direction. In FIG. 16, it is assumed that there are lanes 1 to 3 and lane 2 is the target lane. In addition, a white arrow in the drawing indicates the traveling direction of the vehicle 30. Therefore, in the example of FIG. 16, it is assumed that the traveling direction of the vehicle 30 in the lane 1 and the lane 2 is from right to left, and the traveling direction in the lane 3 is from left to right. In the following description, it is assumed that the vehicle 30a is stopped. On the other hand, the vehicle 30b is traveling from left to right, and the vehicle 30c and the vehicle 30d are traveling from right to left.

It is assumed that the vehicle-mounted sensor 40a mounted on the vehicle 30a irradiates the vehicle 30b with a radar having a frequency fs from the radar transmitter 45b. Then, due to the Doppler effect, the radar frequency fo obtained as a reflected wave from the vehicle 30b becomes lower than fs. Here, the calculation unit 48 uses the threshold value fTh,
fo-fs> fTh
If it is, the calculation unit 18 of the in-vehicle sensor 40a determines that the traveling direction of the vehicle 30b is opposite to the traveling direction of the vehicle 30a. It is assumed that the calculation unit 48 stores fTh in advance. If it is determined by the above procedure that the traveling directions of the vehicle 30a and the vehicle 30b are different, it is determined that the traveling direction of the lane 3 is different from the traveling direction of the lane 2.

  On the other hand, it is assumed that the vehicle-mounted sensor 40a irradiates the vehicle 30d with a signal having the frequency fs from the radar transmitter 45b. Then, due to the Doppler effect, the radar frequency fp obtained as a reflected wave from the vehicle 30d becomes higher than fs. Therefore, the calculation unit 18 of the in-vehicle sensor 40a determines that the traveling direction of the vehicle 30d is the same as the traveling direction of the vehicle 30a. Similarly, the vehicle-mounted sensor 40a can compare the frequency of the reflected wave from the radar vehicle 30c with the transmission frequency fs. Since the vehicle 30c is in the same lane as the vehicle 30a, the in-vehicle sensor 40a does not have to check the traveling direction of the vehicle 30c.

  Although the case where the vehicle 30a is stopped has been described here for the sake of easy understanding, the in-vehicle sensor 40a can also determine the traveling direction using the Doppler effect even when the vehicle 30a is traveling. When the vehicle 30a is traveling, if the speed of the vehicle 30a is higher than the speed of the vehicle 30c, the frequency fp of the reflected wave from the vehicle 30c becomes lower than the frequency fo at the time of transmission. Therefore, fTh is set to a value larger than the amount of change in frequency caused by the difference in the speed of vehicles moving in the same direction.

  In this embodiment, the vehicle-mounted sensor 40 can specify the traveling direction of the lane. Therefore, for example, the in-vehicle sensor 40 mounted on the starting vehicle can specify a lane having the same traveling direction as the target lane. For this reason, the processing burden of the road surface sensor 10 is reduced. The transmission / reception of the observation request message and the transmission / reception of the observation response message performed after the lane having the same traveling direction as the target lane is specified are performed in the same manner as in the first or second embodiment.

<Others>
The embodiment is not limited to the above, and can be variously modified. Some examples are described below.

  The information element of each message may be arbitrarily changed according to the implementation. For example, the measurement request message shown in FIG. 10 may not include the inter-vehicle distance and angle and the length of the transmission source vehicle.

  The measurement response message may be propagated by broadcast transmission. In this case, after transmitting the measurement request message, the in-vehicle sensor 40 may not store the inter-vehicle distance between the preceding vehicle and the angle formed by the straight line connecting the preceding vehicle and the host vehicle with respect to the target lane.

  In the above description, the case where the head vehicle in the traffic jam has received the measurement start message from the road surface sensor 10 has been described as an example. May be. In this case, the measurement request message is transmitted from the rear vehicle to the front vehicle. The measurement response message is sent from the front vehicle to the rear vehicle.

DESCRIPTION OF SYMBOLS 10 Road surface sensor 11, 41 Antenna 12, 42 Data transmission part 13, 43 Data reception part 14, 44 Communication part 15, 45 Radar transmission part 16, 46 Radar reception part 17, 47 Radar processing part 18, 48 Calculation part 21, 51 Interface 22, 53 Control circuit 23, 52 Millimeter wave circuit 24, 54 Memory 40 In-vehicle sensor

Claims (11)

A sensor device mounted on a first vehicle,
Any of the vehicles in the first lane including the starting vehicle may be configured to send a measurement request for determining the length of traffic jam in the first lane starting from the starting vehicle located in the first lane. A data receiver that receives from a vehicle of a certain transmission source;
A radar transmitter for transmitting a radar signal wave toward the transmission source vehicle; a radar reception unit for receiving a reflected wave of a radar signal wave reflected from the transmission source vehicle;
A first distance, which is a distance from the starting vehicle to the transmission source vehicle, notified using the measurement request, a distance from the transmission source vehicle to the first vehicle determined by the reflected wave, and A calculation unit for calculating a second distance, which is a distance from the starting vehicle to the first vehicle, using the length of the first vehicle;
When the first vehicle is located in the first lane, the vehicle is closest to the first vehicle in the first lane that is on the opposite side of the transmission source vehicle. If communication with the second vehicle located at the position fails, a measurement request including the second distance is sent to the third vehicle located in the second lane having the same traveling direction as the first lane. A sensor device comprising a data transmission unit for transmission. When the first vehicle is located in the second lane, the data transmission unit is a vehicle closest to the first vehicle among vehicles located in the first lane. Trying to communicate with the vehicle,
The sensor according to claim 1, wherein when the communication is established with the fourth vehicle, the data transmission unit transmits a measurement request including the second distance to the fourth vehicle. apparatus. When the first vehicle is located in the second lane, the data receiving unit, together with the measurement request, causes the target lane to be measured for the length of the traffic jam and the first vehicle to travel. Receive information identifying the lane you are in,
The calculation unit uses the reflected wave to transmit the radar of the first vehicle starting from the radar reflection position of the transmission source vehicle along with the distance from the transmission source vehicle to the first vehicle. Further determining the angle formed by the vector whose position is the end point with respect to the target lane,
The calculation unit obtains a distance component of the vector in a direction parallel to the target lane, and adds the distance component and the length of the first vehicle to the first distance, thereby calculating the second distance. The sensor device according to claim 1, wherein the sensor device is calculated. Another radar transmitter for transmitting a radar signal wave for detecting a vehicle on the opposite side of the transmission source vehicle;
Another radar receiver that receives a reflected wave of the radar signal wave transmitted from the other radar transmitter;
In the processing result of the received signal at the other radar receiver, when the vehicle is not detected on the side opposite to the transmission source vehicle, the data transmitter is configured to send the second distance and the second distance. The response message including information indicating that the traffic is the length of traffic jam when the starting vehicle is the starting point is transmitted to the transmission source vehicle. The sensor device described. The calculation unit compares the frequency of the received wave, which is a reflected wave of the radar signal wave received by the other radar receiver unit, with the frequency of the transmitted wave, which is a radar signal wave transmitted from the other radar transmitter unit. And
When the frequency of the received wave is higher than the frequency of the transmitted wave, the traveling direction of the vehicle detected using the received signal in the other radar receiver is the same as the traveling direction of the first vehicle. It determines with these. The sensor apparatus of Claim 4 characterized by the above-mentioned. In the case where communication is possible with the third vehicle and a fourth vehicle located in the third lane having the same traveling direction as the first lane, the data transmission unit is configured to transmit the second distance and the A measurement request is transmitted to the 3rd and 4th vehicles. A sensor device given in any 1 paragraph of Claims 1-5 characterized by things. Installed on roads with multiple lanes,
A radar transmitter that transmits a radar signal wave toward a vehicle traveling in the plurality of lanes; a radar receiver that receives a reflected wave of the radar signal wave reflected from the vehicle;
From the processing result of the reflected wave, the travel speed and travel direction of the vehicle in each of the plurality of lanes are calculated, and when traffic congestion occurs in the first lane of the plurality of lanes, the first lane A calculation unit for determining a starting vehicle located in
A measurement request is sent to the starting vehicle for requesting the position of the second lane in the same traveling direction as the first lane and the length of traffic congestion in the first lane starting from the starting vehicle. A data transmitter to
A sensor device comprising: a data receiving unit that receives a response message that notifies a measurement result of a length of traffic jam in the first lane from the starting vehicle. The sensor according to claim 7, wherein the calculation unit, when receiving a plurality of the response messages, determines the length of the traffic jam as the longest distance among the values notified as the length of the traffic jam. apparatus. A road surface sensor installed on a road having a plurality of lanes determines a starting vehicle located in the first lane when a traffic jam occurs in the first lane of the plurality of lanes, and , Sending a message requesting to determine the length of traffic jam in the first lane starting from the starting vehicle,
When the starting vehicle cannot communicate with a first vehicle that is a successor of the starting vehicle located in the first lane, the second vehicle is located in the second lane having the same traveling direction as the first lane. A measurement request that includes the length of the starting vehicle and that requests the measurement of the length of the traffic jam in the first lane,
The second vehicle has a calculated value calculated from a distance from the starting vehicle to the second vehicle obtained by a radar, a length of the second vehicle, and a length of the starting vehicle, It is determined that the traffic congestion in the first lane is long, and the calculated value is notified to a third vehicle located behind the second vehicle in the first lane, and the first lane A method for measuring a congestion distance, characterized by requiring measurement of the length of a lane congestion. In order to obtain the calculated value, the second vehicle uses a radar to determine the distance from the starting vehicle to the second vehicle, the end of the starting vehicle as the start point, and the start of the second vehicle as the end point. Obtaining an angle formed by a first vector with respect to the first lane;
The second vehicle obtains a first distance component in a direction parallel to the first lane of the first vector, and determines the first distance component and the second vehicle in the length of the starting vehicle. A value obtained by adding the length of the first vehicle to the third vehicle located behind the second vehicle in the first lane as the calculated value,
The third vehicle has a second vector with a distance from the second vehicle to the third vehicle by a radar and a tail end of the second vehicle and a start point of the third vehicle. Finds the angle formed by the first lane,
The third vehicle has a second distance component in a direction parallel to the target lane of the second vector and a length of the third vehicle when the radar cannot detect a vehicle following the third vehicle. The traffic distance measurement method according to claim 9, wherein a value obtained by adding to the calculated value is a traffic jam distance of the first lane. In the sensor device mounted on the first vehicle,
Any of the vehicles in the first lane including the starting vehicle may be configured to send a measurement request for determining the length of traffic jam in the first lane starting from the starting vehicle located in the first lane. From a source vehicle,
Transmit radar signal waves toward the transmission source vehicle,
Receiving a reflected wave of a radar signal wave reflected from the transmission source vehicle;
A first distance, which is a distance from the starting vehicle to the transmission source vehicle, notified using the measurement request, a distance from the transmission source vehicle to the first vehicle determined by the reflected wave, and Using the length of the first vehicle to calculate a second distance that is a distance from the starting vehicle to the first vehicle;
When the first vehicle is located in the first lane, the vehicle is closest to the first vehicle in the first lane that is on the opposite side of the transmission source vehicle. If the communication with the second vehicle located at the position fails, the measurement request including the second distance is included in the third vehicle located in the second lane having the same traveling direction as the first lane. A measurement program characterized by causing processing to be performed.