JP2010282283A - Intersection warning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately control a start distance according to the degree of congestion of vehicles, in an intersection warning device for executing an application for issuing a warning when a self-vehicle enters a start distance from an intersection. <P>SOLUTION: On the basis of a radio wave received from the other vehicle, the index of the degree of congestion of vehicles in the periphery of a self-vehicle 4 is acquired, and on the basis of the acquired index of the degree of congestion, a start distance is made longer as the degrees of congestion of vehicles 7, 31 and 32 in the periphery of the self-vehicle is higher, and the start distance is made shorter as the degree of congestion is lower. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intersection warning device.

  Conventionally, in order to support the prevention of collision between vehicles at an intersection, a device that acquires information on the position of the opponent vehicle by inter-vehicle communication and warns when there is a risk of collision based on the acquired position information Known (see, for example, Patent Documents 1 and 2). Some of these intersection warning devices execute an application for giving a warning when the host vehicle enters a predetermined starting distance from the intersection. Conventionally, this starting distance has been a fixed range.

JP 2009-9486 A JP 2005-227978 A

  However, according to the inventor's study, the following problems occur when the activation distance is fixed. That is, as shown in FIG. 12, when the vehicle 61 is traveling on the road 51 toward the intersection 53 and a large number of vehicles 62 to 64 are traveling toward the intersection 53 from another direction, The possibility of collision with these vehicles 62 to 64 is relatively high. Accordingly, the execution timing of the application for issuing a warning is desired to be advanced, but if the activation distance 55 from the origin node 59 is fixed, the warning may be delayed.

  On the other hand, as shown in FIG. 13, when there are few vehicles entering from a direction different from the vehicle 61, the possibility of collision with the vehicle 65 is low. Therefore, the execution timing of the application for issuing a warning may be late, but if the activation distance 55 from the starting node 59 is fixed, an unnecessary warning may be issued.

  In view of the above points, the present invention appropriately controls the activation distance according to the degree of congestion of the vehicle in the intersection warning device that executes an application for giving a warning when the host vehicle enters the activation distance from the intersection. With the goal.

  The invention according to claim 1 for achieving the above object is an intersection warning device mounted on the first vehicle (4), which receives radio waves transmitted from each of a plurality of other vehicles, The receiving means (11) for acquiring a packet including information on the position of each of a plurality of other vehicles from the received radio wave, and whether the distance from the position of the intersection to the first vehicle (4) is within the starting distance When the determination means (135) determines that the distance from the intersection position to the first vehicle (4) is within the starting distance, the warning application is executed. In the execution of the start control means (137) to be started and the warning application, the risk of collision at the intersection is determined based on the information on the positions of other vehicles in the packet acquired by the reception means (11). Whether to warn the driver of the vehicle (4), and warning means (140 to 160) for warning the driver based on the decision to warn, and the receiving means (11) are a plurality of other vehicles Congestion degree index acquisition means (120, 220, 230) for acquiring a congestion degree index for vehicles around the first vehicle (4) based on the radio wave received from the first vehicle (4), and congestion degree index acquisition means (120, 220). 230), the range determining means (130, 230, 330) for increasing the starting distance as the degree of congestion of the vehicles around the first vehicle (4) increases. It is characterized by having.

  In this way, in the intersection warning device that executes the warning application when the first vehicle (4) enters the start distance from the intersection, an index of the congestion degree of the vehicles around the first vehicle (4) is acquired. Then, based on the acquired congestion degree index, the activation distance is appropriately set according to the congestion degree of the vehicle by increasing the activation distance as the congestion degree of the vehicles around the first vehicle (4) increases. Can be controlled.

  In addition, as described in claim 2, a packet in a radio wave transmitted from each of a plurality of other vehicles and received by the receiving unit (11) includes a vehicle ID of the vehicle together with information on the position of the vehicle. The congestion degree index acquisition means (120, 220, 230) acquires a real number of vehicle IDs received from a plurality of other vehicles within the first predetermined period as an index of the congestion degree. Also good.

  Further, as described in claim 3, the congestion degree index acquisition means (120, 220, 230) calculates an average received power of packets in radio waves received from a plurality of other vehicles within the second predetermined period, It may be acquired as an indicator of the degree of congestion.

  In addition, as described in claim 4, the congestion index obtaining means (120, 220, 230) calculates the packet error rate of packets in radio waves received from a plurality of other vehicles within the third predetermined period. It may be acquired as an indicator of the degree of congestion.

  In addition, the code | symbol in the bracket | parenthesis in the said and the claim shows the correspondence of the term described in the claim, and the concrete thing etc. which illustrate the said term described in embodiment mentioned later. .

It is a schematic diagram which shows the outline | summary of the encounter collision prevention assistance which concerns on 1st Embodiment of this invention. It is a figure showing composition of encounter intersection warning device 10 carried in vehicles. 2 is a diagram illustrating a configuration of a control device 13. FIG. It is a flowchart which shows the procedure of the process of the microcomputer 13c. It is a flowchart of an encounter collision warning application. It is a figure which shows the starting distance 46 when the circumference | surroundings of the own vehicle 4 are congested rather than usual. It is a figure which shows the starting distance 47 when the circumference | surroundings of the own vehicle 4 are sparser than usual. It is a figure which shows the structure of the control apparatus 13 in 2nd Embodiment. It is a flowchart which shows the procedure of the process of the microcomputer 13c in 2nd Embodiment. It is a figure which shows the structure of the control apparatus 13 in 3rd Embodiment. It is a flowchart which shows the procedure of the process of the microcomputer 13c in 3rd Embodiment. It is a figure which shows the case where the circumference | surroundings of the vehicle 61 are crowded. It is a figure which shows the case where the circumference | surroundings of the vehicle 61 are sparse.

(First embodiment)
The first embodiment of the present invention will be described below. As illustrated in FIG. 1, the present embodiment aims to support prevention of encounter collisions by vehicles 4 to 8 at an intersection 3 where roads 1 and 2 intersect.

  For example, since the vehicle 4 that is about to enter the intersection 3 from the road 1 may encounter a head-on collision with the vehicle 7 that is about to enter the intersection 3 from the road 2, it is preferable to warn the driver. In such a case, the intersection warning device provided in the vehicle 4 and the vehicle 7 warns the driver of the vehicle 4 and 7, respectively, thereby assisting in preventing the encounter collision by the vehicles 4 and 7.

  In order to support the prevention of such an encounter collision, an encounter collision prevention support apparatus 10 as shown in FIG. 2 is mounted on each of a plurality of vehicles (for example, vehicles 4 to 8 in FIG. 1). These encounter collision prevention support apparatuses 10 collect information on the position of the own vehicle and information on the traveling direction of the own vehicle into one packet by inter-vehicle wireless communication, transmit the packet including the radio wave, and Receiving the radio wave transmitted from each of the vehicles, obtaining a packet from the received radio wave, obtaining information on the position of the vehicle and information on the traveling direction of the vehicle included in the obtained packet, Based on this, it is determined whether or not to warn the driver of an encounter collision.

  For example, the intersection warning device 10 of the vehicle 4 is configured to provide a predetermined information provision range centered on the own vehicle 4 when the own vehicle 4 approaches a reference distance 45 or less with respect to the base node 9 set in advance at the position of the intersection 3. For each of the vehicles 5 to 7 in the vehicle 40, it is determined whether or not the vehicle 5 is traveling in the direction intersecting with the own vehicle 4, and if there is a vehicle traveling in the intersecting direction, the driver of the own vehicle 4 is And warn of a head-on collision. The feature of this embodiment is that the size of the reference distance 45 changes. Hereinafter, the reference distance 45 is referred to as an activation distance.

  Here, the configuration of the intersection warning device 10 will be described. As shown in FIG. 2, the intersection warning device 10 includes a radio device 11, a navigation device 12, and a control device 13.

  The wireless device 11 (corresponding to an example of a receiving unit) is a device for realizing vehicle-to-vehicle wireless communication. The wireless device 11 amplifies, converts frequency, demodulates, and transmits radio waves (including data packets) received by an antenna. Processing according to a predetermined wireless communication protocol (for example, DSRC, cellular phone data communication) such as / D conversion is performed, and a data packet (hereinafter referred to as a received packet) obtained as a result is output to the control device 13. In addition, the wireless device 11 performs processing according to a predetermined wireless communication protocol, such as D / A conversion, modulation, frequency conversion, amplification, etc., on a transmission data packet (hereinafter referred to as a transmission packet) received from the control device 13. And the resulting signal is output to the antenna. Thereby, the radio wave including the transmission packet is transmitted. By using the wireless device 11 that performs such an operation, the control device 13 can realize wireless communication (that is, vehicle-to-vehicle communication) of the encounter collision prevention support device 10 of another vehicle.

  The navigation device 12 is a device that calculates an optimal route from the current position to the destination and guides the vehicle to move along the calculated route. This guidance is performed by sound and image using a speaker and an image display device mounted in the vehicle. The navigation device 12 includes a sensor group such as a GPS receiver, a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor, and specifies the current position, traveling direction, traveling speed, and the like of the host vehicle based on signals from these sensor groups. It is like that.

  Further, the navigation device 12 controls the content of the sound output to the speaker and the content of the image displayed on the image display device in response to a command from the control device 13. The navigation device 12 outputs information such as the current position of the host vehicle, the traveling direction, and the traveling speed to the control device 13 in response to a request from the control device 13.

  The control device 13 includes a packet reception storage buffer 13a, a packet transmission storage buffer 13b, and a microcomputer 13c. The packet reception storage buffer 13a is a storage device that acquires and accumulates received packets output from the wireless device 11 to the control device 13. When the received packet is stored, information on the time when the received packet is stored is recorded in association with the received packet. The time when the received packet is accumulated is substantially the same as the time when the wireless device 11 receives the radio wave and acquires the received packet. Therefore, by doing this, it becomes possible to know when the stored received packets are received.

  The packet transmission storage buffer 13b is a storage device that temporarily stores the transmission packet output from the microcomputer 13c and outputs the transmission packet to the wireless device 11 at a predetermined timing (for example, once every 100 milliseconds). .

  The microcomputer 13c includes a CPU, a RAM, and a ROM (not shown), and the CPU executes various programs by executing programs stored in the ROM. Specifically, the functions realized by the microcomputer 13c include an own vehicle information transmission function 21, a vehicle number calculation function 22, an activation distance determination function 23, an information provision determination function 24, and the like.

  The own vehicle information transmission function 21 is a function that wirelessly transmits information on the own vehicle periodically (for example, every 100 milliseconds). In order to realize the vehicle information transmission function 21, the microcomputer 13c periodically requests and obtains information about the current position and traveling direction of the vehicle from the navigation device 12, and stores the information in the ROM. Information on the vehicle ID of the host vehicle recorded in advance is read. Then, information on the vehicle ID, position, and traveling direction of the host vehicle is included in one transmission packet and output to the packet transmission storage buffer 13b. As a result, the packet transmission storage buffer 13b periodically outputs the transmission packet to the wireless device 11 at a predetermined timing. As a result, the wireless device 11 wirelessly transmits a transmission packet including information on the vehicle ID, the own vehicle position, and the traveling direction of the own vehicle to surrounding vehicles periodically at a predetermined timing. Hereinafter, such a transmission packet including information of vehicle travel information (specifically, vehicle ID, host vehicle position, and travel direction of the host vehicle) is referred to as a vehicle information packet.

  The vehicle number calculation function 22 is transmitted from the other vehicle, received by the wireless device 11 of the own vehicle, and stored in the packet reception storage buffer 13a of the control device 13 in the vehicle information packet originating from the other vehicle (that is, the received packet). This is a function of calculating the number of vehicles around the host vehicle based on the vehicle ID.

  In order to realize the vehicle number calculation function 22, the microcomputer 13c reads out received packets received within a predetermined period (corresponding to a first predetermined period) retroactive from the packet reception storage buffer 13a. This predetermined period is a period longer than the vehicle information packet transmission cycle in the intersection warning device 10.

  Then, the microcomputer 13c counts the number of vehicle IDs in the read reception packet. At this time, even if there are a plurality of vehicle IDs having the same value, they are counted as one.

  The number of vehicle IDs counted in this way is vehicle information from a communicable range of the own vehicle (for example, inside a circle having a radius of about 300 meters to 400 meters centered on the own vehicle) within a predetermined period retroactive to the present. This is the number of vehicles that have transmitted packets (not real numbers). Therefore, since the number of vehicles counted in this way is the number of other vehicles within the communicable range of the own vehicle, it becomes an index of the degree of congestion of the vehicle around the own vehicle.

  The activation distance determination function 23 is a function that determines the activation distance based on the number of vehicles calculated by the vehicle number calculation function 22.

  In order to realize the activation distance determination function 23, the microcomputer 13c determines the information provision range with reference to the number-distance table recorded in the ROM. The number-distance table is a table that defines the correspondence between the number of vehicles and the starting distance. Specifically, in the number-distance table, the number of vehicles is classified into three: a normal range, a sparse range less than the normal range, and a congestion range greater than the normal range. Each is associated with one activation distance. More specifically, the activation distance assigned to the sparse range (eg, 150 meters) is shorter than the activation distance assigned to the normal range (eg, 200 meters), and the activation distance assigned to the crowded range (eg, 250 meters) is It is longer than the starting distance assigned to the normal range.

  Based on the activation distance determined by the activation distance determination function 23, the information provision determination function 24 warns of an encounter collision when the distance between the host vehicle and the base node 9 is within the activation distance (that is, information This is a function for executing a warning when it is determined whether or not to provide, and when it is determined to perform a warning. The specific contents of this function will be described later.

  Hereinafter, operation procedures of functions corresponding to the vehicle number calculation function 22, the activation distance determination function 23, and the information provision determination function 24 will be described with reference to the flowchart of FIG. In addition, the function of the own vehicle information transmission function 21 is performed in parallel with the processing of the flowchart of FIG. The vehicle number calculation function 22 is realized by the processing of steps 110 and 120 in FIG. 4, the activation distance determination function 23 is realized by the processing of step 130, and the information provision determination function 24 is realized by the processing of steps 135 and 137.

  The microcomputer 13c repeatedly performs the process shown in FIG. 4 while the intersection warning device 10 is operating (that is, while the engine of the host vehicle is on).

  Then, in each execution of the processing of FIG. 4, the microcomputer 13c first reads and acquires the received packet received in a predetermined period going back from the present from the packet reception storage buffer 13a in step 110. Subsequently, in step 120, as already described, the number of vehicle IDs in the received packet read in step 110 (not a total number but a real number (that is, a different number)) is counted. As already described, the number of vehicle IDs is the real number of other vehicles within the communicable range of the host vehicle.

  Subsequently, in step 130, the above-described number-distance table is referred to, and the activation distance corresponding to the real number of vehicles counted in step 120 is determined. Subsequently, in step 135, it is determined whether or not the linear distance from the host vehicle to the starting node is equal to or less than the activation distance determined in step 130. That is, it is determined whether or not the own vehicle has entered the starting distance from the starting point node. The base node is the position of an intersection that is considered to have a high risk of encounter collision. The position of the base node is recorded in advance in the ROM of the microcomputer 13c. The current position of the host vehicle is acquired by requesting the navigation device 12.

  As long as the host vehicle does not fall within the starting distance from the starting node, step 110 is executed following step 135, and thus the processing of steps 10 to 135 is repeated. Therefore, the activation distance sequentially changes according to the change in the real number of the vehicle ID in the received packet.

  When the host vehicle enters the starting distance from the starting node, in step 137 following step 135, an encounter warning application (corresponding to an example of a warning application) is executed. Therefore, the determination process in step 135 is a control process for starting the encounter warning application.

  The encounter warning application is a program recorded in the ROM or the like of the microcomputer 13c, and is an application for giving a warning to the driver of the own vehicle by voice or image when there is a high possibility that the own vehicle encounters a collision at the intersection. It is.

  FIG. 5 shows a flowchart of this encounter warning application. As shown in this figure, when the encounter warning application is executed, the microcomputer 13c first determines in step 140 the position received from each of the newly received packets read in step 140 among the received packets read out in this time step 140. Information is read out, and it is determined whether or not each position is within an information provision range centered on the host vehicle. The position of the host vehicle is acquired by requesting the navigation device 12. If it is determined that even one of them is within the information provision range, then step 150 is executed. If it is determined that none of them is within the information provision range, step 150 is performed. Bypassing 150 and 160, the process for one time in FIG.

  The reason for bypassing steps 150 and 160 in this way is that it is too early to warn of a head-on collision because the distance between the other vehicle of the transmission source of the received packet and the host vehicle is sufficiently large. Is based.

  Note that the “new received packet newly read in step 140” means that the received packet other than the read packet read in the previous step 140 at the second and subsequent execution opportunities of step 140 after the start of execution of the encounter warning application. In the first execution opportunity of step 140 after the start of execution of the encounter warning application, all received received packets are read.

  In step 150, it is determined whether or not an encounter collision warning (that is, information provision) is to be issued. Specifically, whether or not to warn each other vehicle at the position determined to be within the information providing range in step 140 if the traveling direction of the own vehicle and the traveling direction of the other vehicle intersect. If at least one crosses, it is determined to warn, and if none intersect, it is determined not to warn.

  Note that the traveling direction of the host vehicle is acquired by requesting the navigation device 12. The traveling direction of the other vehicle is determined based on the traveling direction in the latest received packet.

  Further, as to whether or not the traveling direction of the own vehicle and the traveling direction of the other vehicle intersect, for example, an angle θ (where 0 ° ≦ θ ≦ 180) formed by the traveling direction of the own vehicle and the traveling direction of the other vehicle. Is determined to be crossing the traveling direction of the host vehicle and the traveling direction of the other vehicle when the first predetermined angle (for example, 45 °) or more and the second predetermined angle (for example, 135 °) or less. In other cases, it may be determined that the traveling direction of the host vehicle and the traveling direction of the other vehicle do not intersect.

  If it is determined that a warning is to be issued, then in step 160, the navigation device 12 is instructed to issue a warning by sound and image. In response to this command, the navigation device 12 outputs a voice warning that there is a risk of encounter clash (for example, a voice “Please be careful about encounter clash”) to the speaker, and there is a risk of encounter clash. An image warning device is displayed on the image display device. This warning may be continued for a predetermined time (for example, 10 seconds), or may be continued until the own vehicle passes the position of an intersection (more specifically, a base node). After step 160, execution of the encounter warning application is terminated, and step 110 of the process of FIG. 4 is executed again.

  The process for one time in FIG. 4 is terminated. If it is determined that no warning is to be issued, the warning process in step 160 is bypassed and step 155 is executed.

  In step 155, it is determined whether or not the vehicle has passed the position of the intersection (more specifically, the base node). If not, step 140 is executed. If the vehicle has passed, execution of the encounter warning application is terminated. Then, step 110 of the process of FIG. 4 is executed again.

  As described above, in the execution of the encounter warning application, the microcomputer 13c, if the other vehicle from which the latest received packet is transmitted is within the information provision range (see step 140), the traveling direction of the other vehicle and the traveling of the host vehicle. It is determined whether or not the vehicle intersects the direction (see step 150). If the vehicle intersects, an encounter collision warning is issued. If the vehicle does not intersect, the vehicle does not issue an encounter collision warning. Repeat until you pass the node.

  Accordingly, the intersection warning device 10 does not warn of an encounter collision and crosses the traveling direction of the own vehicle while another vehicle traveling in a direction intersecting the traveling direction of the own vehicle does not enter the information providing range. If any other vehicle traveling in the direction enters the information provision range, a head-on collision warning is given.

  As described above, the intersection warning device 10 executes the encounter warning application (see step 137) when the own vehicle enters within the starting distance before the starting node (see step 135). Based on the information on the position of the other vehicle and the information on the traveling direction of the host vehicle and the other vehicle, it is determined whether or not to warn of the encounter collision (see steps 140 and 150). Then, after giving a warning (see step 160) and when the host vehicle passes the starting point node before giving the warning (see step 155), the execution of the encounter warning application is terminated.

  For example, in the scene shown in FIG. 1, the intersection warning device 10 mounted on the vehicle 4 (corresponding to an example of the first vehicle) enters the range where the own vehicle 4 is within the activation distance 45 from the origin node 9. And run an encounter warning application. During the execution, when another vehicle 7 (corresponding to an example of the second vehicle) enters the information providing range 40 of the own vehicle 4, based on the vehicle information packet transmitted from the other vehicle 7, It is determined that the other vehicle 7 has entered the information provision range 40 (see step 140), and further, it is determined that the traveling direction of the other vehicle 7 intersects the traveling direction of the host vehicle (see step 150), and then a warning is issued. (See step 160), and then the encounter warning application is terminated.

  In addition, the intersection warning device 10 indicates that the real number of other vehicles that transmitted the vehicle information packet received within a predetermined period retroactive from the present time (that is, the real number of vehicle IDs received from other vehicles within the predetermined period). When the vehicle is outside the normal range, that is, when other vehicles are more crowded around the host vehicle than usual, the starting distance is increased more than usual. In addition, the intersection warning device 10 is configured so that when the actual number of other vehicles that have transmitted the vehicle information packet received within a predetermined period retroactive from the present time is below the normal range, that is, the other vehicles are around the subject vehicle. If it is sparser than usual, the activation distance is made smaller than usual.

  As described above, the effect of increasing the starting distance as the congestion degree of other vehicles around the host vehicle increases is described. The fact that there are many other vehicles around the host vehicle means that, as shown in FIG. 6, there are a large number of vehicles 7, 31, 32 in front of the intersection 3 on the road 2 that intersects the road 1 where the host vehicle 4 is located. It is highly possible that In such a case, the possibility that the host vehicle 4 encounters the vehicles 7, 31, 32 and causes a head-on collision is relatively high. Therefore, it is desirable to warn the driver earlier.

  At this time, if the activation distance 46 longer than the normal activation distance 45 is adopted as in the present embodiment, the activation of the encounter warning application is accelerated accordingly, and the warning to the driver of the own vehicle 4 is also accelerated accordingly.

  On the contrary, the fact that the number of vehicles around the host vehicle is small means that, as shown in FIG. 7, the number of vehicles in front of the intersection 3 is reduced on the road 2 that intersects the road 1 where the host vehicle 4 is located. There is a high possibility. In such a case, the possibility of encountering another vehicle on the road 2 where the host vehicle 4 intersects and causing a head-on collision is reduced. Therefore, the warning timing for the driver may be relatively late.

  At this time, if the activation distance 45 shorter than the normal activation distance 45 is employed as in the present embodiment, the activation of the encounter warning application is delayed that much. Therefore, the possibility that the warning of an encounter collision is performed unnecessarily quickly is reduced. Further, since the encounter warning application is not executed unnecessarily quickly, the processing load on the intersection warning device 10 is reduced. Further, since the microcomputer 13c of the present embodiment is configured so that other applications cannot be executed when the encounter warning application is being executed, the encounter warning application can be prevented from being executed unnecessarily quickly. Increases the period during which other applications can be run.

  In this way, in the intersection warning device that executes the warning application when the own vehicle (for example, the vehicle 4) enters the start distance from the intersection, an indicator of the degree of congestion of the vehicles around the own vehicle is acquired, and the acquired congestion is obtained. Based on the degree index, the higher the congestion level of the vehicle around the host vehicle, the longer the startup distance, and the lower the congestion level of the vehicle around the host vehicle, the shorter the startup distance, The starting distance can be appropriately controlled according to the degree.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with a focus on differences from the first embodiment. This embodiment is different from the first embodiment in the first embodiment, where the number of vehicles in the communicable range is used as an indicator of the degree of congestion around the host vehicle. The received power of the vehicle information packet (that is, the received packet) received from another vehicle is used. This received power corresponds to an example of a radio wave environment when the wireless device 11 receives a vehicle information packet.

  For this purpose, the wireless device 11 has an RSSI circuit (not shown) that outputs the received signal strength of radio waves, and as shown in FIG. 8, the control device 13 acquires the output of the RSSI circuit. ing.

  More specifically, the packet reception storage buffer 13a is associated with the received packet and records the output of the RSSI circuit when the received packet is received. The microcomputer 13c implements a received power calculation function 25 instead of the vehicle number calculation function 22.

  The received power calculation function 25 is a function for calculating the average received power of the wireless device 11 when a received packet is received. In order to realize this received power calculation function 25, the microcomputer 13c causes the RSSI associated with the received packet received from the packet reception storage buffer 13a within a predetermined period (corresponding to the second predetermined period) retroactive to the present. Read the output. These read RSSI output values are the received signal strengths when receiving the corresponding received packets. This predetermined period is a period longer than the vehicle information packet transmission cycle in the intersection warning device 10. The packet reception storage buffer 13a calculates reception power (dBm) from each of the read reception signal strengths, and calculates an average value of these reception powers.

  That is, when N vehicle transmission packets are received within a predetermined period retroactive from the present, if the received power at the time of receiving each vehicle transmission packet is Pi (i = 1, 2,..., N), the average The received power is ΣPi / N. However, Σ means the sum of 1 to N for i.

  The average received power calculated in this way is a value that increases as the other vehicles within the communicable range of the host vehicle are biased closer to the host vehicle. Therefore, the average received power calculated in this way is an indicator of the degree of congestion of the vehicle around the host vehicle.

  In addition, the activation distance determination function 23 of the present embodiment determines the activation distance based on the average reception power calculated by the reception power calculation function 25.

  In order to realize the activation distance determination function 23, the microcomputer 13c determines the activation distance with reference to the power-distance table recorded in the ROM. The power-distance table is a table that defines a correspondence relationship between average received power and distance. Specifically, in the power-distance table, the power is classified into three ranges: a normal range, a small power range smaller than the normal range, and a large power range larger than the normal range, and these three power ranges. Each is associated with one activation distance. More specifically, the start distance (eg, 150 meters) assigned to the low power range is shorter than the start distance (eg, 200 meters) assigned to the normal range, and the start distance (eg, 250 meters) assigned to the high power range. Is longer than the activation distance assigned to the normal range.

  Hereinafter, operation procedures of functions corresponding to the received power calculation function 25 and the activation distance determination function 23 will be described with reference to the flowchart of FIG. In addition, the function of the own vehicle information transmission function 21 is performed in parallel with the process of the flowchart of FIG. The received power calculation function 25 is realized by the processing of steps 210 and 220 in FIG. 8, the activation distance determination function 23 is realized by the processing of step 230, and the information provision determination function 24 is realized by the processing of steps 135 and 137. Note that the processing contents of steps 135 and 137 are the same as the processing contents of steps 135 and 137 in FIG.

  The microcomputer 13c repeatedly executes the process shown in FIG. 9 while the intersection warning device 10 is in operation (that is, while the engine of the host vehicle is on). Then, in each execution of the processing of FIG. 9, the microcomputer 13c first receives in step 210 the received packets received within a predetermined period retroactive from the present time and the received signal strength associated therewith from the packet reception storage buffer 13a. Read and get. Subsequently, in step 220, as already described, the received power is calculated from the received signal strength read in step 210, and the average value thereof is further calculated.

  Subsequently, in step 230, the power-distance table described above is referred to determine an activation distance corresponding to the average received power calculated in step 220, and then step 135 is executed.

  As described above, the intersection warning device 10 according to the present embodiment uses the average value of the received power at the time of receiving the vehicle information packet as an index of the congestion degree of other vehicles around the host vehicle, and according to the average received power. Change the starting distance. Therefore, the same effect as the first embodiment can be obtained. In addition, since the radio device 11 often has an RSSI circuit, an index of the congestion degree can be easily calculated by using the output of such an RSSI circuit.

(Third embodiment)
Next, a third embodiment of the present invention will be described with a focus on differences from the first embodiment. This embodiment is different from the first embodiment in the first embodiment, where the number of vehicles in the communicable range is used as an indicator of the degree of congestion around the host vehicle. The point is that a packet error ratio (PER) of a vehicle information packet (that is, a received packet) received from another vehicle is used. This packet error rate corresponds to an example of a radio wave environment when the vehicle information packet is received by the wireless device 11.

  For this reason, the wireless device 11 outputs a packet error rate as shown in FIG. The packet error rate refers to the ratio of vehicle information packets with transmission errors out of all vehicle information packets received within a predetermined period (corresponding to a third predetermined period) retroactive from the present. The wireless device 11 that outputs a packet error rate is well known. For example, the wireless device 11 performs error detection such as cyclic redundancy check (CRC) on the received vehicle information packet to determine whether each vehicle information packet has a transmission error.

  Further, the microcomputer 13c realizes a PER acquisition function 26 instead of the vehicle number calculation function 22. The PER acquisition function 26 is a function for acquiring the packet error rate output from the wireless device 11 as described above.

  By realizing such a PER acquisition function 26, the packet error rate acquired by the microcomputer 13c increases as other vehicles are congested around the host vehicle. This is because as the other vehicles are congested around the host vehicle, obstacles for wireless transmission increase. Therefore, the packet error rate is an indicator of the degree of congestion of the vehicle around the host vehicle.

  In addition, the activation distance determination function 23 of this embodiment determines the activation distance based on the packet error rate acquired by the PER acquisition function 26.

  In order to realize the activation distance determination function 23, the microcomputer 13c determines the activation distance with reference to the PER-distance table recorded in the ROM. The PER-distance table is a table that defines the correspondence between the packet error rate and the activation distance. Specifically, in the PER-distance table, the packet error rate is classified into three groups: a normal range, a low error range smaller than the normal range, and a high error range larger than the normal range. One activation distance is associated with each error rate range. More specifically, the activation distance assigned to the low error range (eg, 150 meters) is shorter than the activation distance assigned to the normal range (eg, 200 meters), and the activation distance assigned to the high error range (eg, 250 meters). Is longer than the activation distance assigned to the normal range.

  Hereinafter, the operation procedure of the functions corresponding to the PER acquisition function 26 and the activation distance determination function 23 will be described with reference to the flowchart of FIG. In addition, the function of the own vehicle information transmission function 21 is performed in parallel with the processing of the flowchart of FIG. The PER acquisition function 26 is realized by the processing of steps 310 and 320 in FIG. 11, the activation distance determination function 23 is realized by the processing of step 330, and the information provision determination function 24 is realized by the processing of steps 135 and 137. Note that the processing contents of steps 135 and 137 are the same as the processing contents of steps 135 and 137 in FIG.

  The microcomputer 13c repeatedly executes the processing shown in FIG. 11 while the intersection warning device 10 is operating (that is, while the engine of the host vehicle is on). Then, in each execution of the processing of FIG. 11, the microcomputer 13 c first obtains a received packet received within a predetermined period going back from the present time in step 310. Subsequently, at step 320, as already described, the packet error rate output from the wireless device 11 is acquired.

  Subsequently, in step 330, the above-described PER-distance table is referred to determine the size of the activation distance corresponding to the packet error rate calculated in step 320, and then step 135 is executed.

  As described above, the intersection warning device 10 according to the present embodiment uses the packet error rate of the received packet as an indicator of the congestion degree of other vehicles around the host vehicle, and changes the activation distance according to the acquisition of the packet error rate. Let Therefore, the same effect as the first embodiment can be obtained. In addition, since the wireless device 11 outputs a packet error rate in many cases, it is possible to easily calculate a congestion degree index by using such output.

  In each of the above embodiments, the microcomputer 13c functions as an example of the congestion index acquisition unit by executing any one of steps 120, 220, and 230, and executes any one of steps 130, 230, and 330. Thus, it functions as an example of a determination unit by executing Step 135, and functions as an example of a start control unit by executing Step 137, and executes Steps 140 to 160 It functions as an example of a warning means.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, the scope of the present invention is not limited only to the said embodiment, The various form which can implement | achieve the function of each invention specific matter of this invention is included. It is.

  For example, in the above-described embodiment, the microcomputer 13c acquires an index of the degree of congestion of vehicles around the host vehicle based on radio waves received by the wireless device 11 from other vehicles. Specifically, in the first embodiment, the actual number of vehicle IDs received from a plurality of other vehicles within the first predetermined period is used as an indicator of the degree of congestion, and in the second embodiment, within the second predetermined period. In the third embodiment, the average received power of packets in radio waves received from a plurality of other vehicles is used as an indicator of the degree of congestion. In the third embodiment, packets in radio waves received from a plurality of other vehicles within a third predetermined period. The packet error rate is used as an index of the degree of congestion. However, the microcomputer 13c acquires information other than the information shown in the first to third embodiments on the basis of radio waves received from a plurality of other vehicles, and uses the information as an indicator of the degree of congestion. It may be.

  In the above embodiment, the intersection warning device 10 executes the encounter collision warning application at the timing when the host vehicle enters the starting distance to the starting node. However, the application that is activated at the timing when the host vehicle is within the activation distance to the starting node is not necessarily an encounter collision warning application, and may be, for example, a right-right collision warning application.

  A right-handed collision means that when the host vehicle tries to turn right at an intersection, it collides with a vehicle traveling straight on the opposite lane. The right-hand collision warning application is a program recorded in a ROM or the like of the microcomputer 13c, and gives a warning by voice and image to the driver of the host vehicle when the host vehicle is highly likely to cause a right-hand collision at an intersection. Is a right-right collision warning application (corresponding to an example of a warning application).

  The specific processing content of the right-right collision warning application is obtained by changing the determination in step 150 in the flowchart of FIG. That is, in step 150, it is determined whether or not to warn right collision (that is, to provide information). More specifically, in step 150, if the traveling direction of the host vehicle and the traveling direction of the other vehicle are reversed, it is determined to warn, and if not reversed, it is determined not to warn.

  Whether or not the traveling direction of the host vehicle and the traveling direction of the other vehicle are reversed is determined by, for example, an angle θ (where 0 ° ≦ θ ≦) between the traveling direction of the host vehicle and the traveling direction of the other vehicle. 180 °) is 150 ° or more, it is determined that the traveling direction of the own vehicle and the traveling direction of the other vehicle are opposite. In other cases, the traveling direction of the own vehicle and the traveling direction of the other vehicle It may be determined that is not reversed.

  As described above, the application that starts when the host vehicle enters the starting distance to the starting node is any warning application that warns the driver of the host vehicle of the danger of a collision at an intersection. There may be.

  For example, in the first embodiment, the activation distance is changed based on an index of the real number of vehicles that are the transmission source of the vehicle information packet received within a predetermined period. In the second embodiment, the vehicle information packet within the predetermined period is changed. The activation distance is changed based on an index of average received power, and in the third embodiment, the activation distance is changed based on an index of packet error rate of the received vehicle information packet. However, the activation distance may be changed based on two or more of these three indexes. For example, the activation distance may be made longer than usual only when the average received power is larger than the normal range and the packet error rate is larger than normal.

  In the above-described embodiment, the activation distance is changed according to an indicator of the degree of congestion around the host vehicle (more specifically, the amount that increases as the surrounding of the host vehicle becomes crowded). However, in addition to the said parameter | index, it may change according to another factor. For example, the microcomputer 13c may change the magnitude of the activation distance according to the traveling speed of the host vehicle.

  The wireless device 11 and the control device 13 may be connected via an in-vehicle LAN (for example, a LAN conforming to the Ethernet (registered trademark) standard). In this case, a transmission packet, a reception packet, a signal indicating the received radio wave intensity, and a signal indicating the packet error rate are exchanged between the wireless device 11 and the control device 13 via the in-vehicle LAN.

  In the above embodiment, each function realized by the microcomputer 13c executing a program is realized by using hardware having those functions (for example, an FPGA capable of programming a circuit configuration). You may come to do.

1, 2, 51, 52 Road 3, 53 Intersections 4-8, 31-33, 61-64 Vehicles 9, 59 Origin node 10 Intersection warning device 11 Radio 12 Navigation device 13 Control device 13a Packet reception storage buffer 13b Packet transmission Save buffer 13c Microcomputer 21 Vehicle information transmission function 22 Number of vehicles calculation function 23 Start distance determination function 24 Information provision determination function 25 Received power calculation function 26 PER acquisition function 40 Information provision range 45 to 47, 55 Start distance

Claims (4)

An intersection warning device mounted on a first vehicle (4),
Receiving means (11) for receiving a radio wave transmitted from each of a plurality of other vehicles, and obtaining a packet including information on the position of each of the plurality of other vehicles from the received radio waves;
Determination means (135) for determining whether or not the distance from the position of the intersection to the first vehicle (4) is within an activation distance;
Start control means (137) for starting execution of a warning application when the determination means (135) determines that the distance from the intersection position to the first vehicle (4) is within an activation distance; ,
In the execution of the warning application, based on the information on the positions of the plurality of other vehicles in the packet acquired by the receiving means (11), the risk of collision at the intersection is determined by the first vehicle (4). Warning means (140 to 160) for warning whether the driver is warned, and warning the driver based on the judgment that the driver is warned,
Based on the radio waves received from the plurality of other vehicles by the receiving means (11), the congestion degree obtaining means (120, 220, 230)
Based on the congestion index acquired by the congestion index acquisition means (120, 220, 230), the higher the congestion of vehicles around the first vehicle (4), the longer the activation distance. An intersection warning device comprising range determining means (130, 230, 330). The packet in the radio wave transmitted from each of the plurality of other vehicles and received by the receiving means (11) includes the vehicle ID of the vehicle together with information on the position of the vehicle,
The congestion level index acquisition means (120, 220, 230) acquires a real number of vehicle IDs received from a plurality of other vehicles within a first predetermined period as the congestion level index. Item 2. An encounter collision prevention support device according to Item 1.   The congestion index acquisition means (120, 220, 230) acquires the average received power of the packets in the radio waves received from the plurality of other vehicles within a second predetermined period as the congestion index. 3. The encounter collision prevention support apparatus according to claim 1 or 2.   The congestion index acquisition means (120, 220, 230) acquires a packet error rate of the packet in radio waves received from the plurality of other vehicles within a third predetermined period as the congestion index. An encounter collision prevention support apparatus according to any one of claims 1 to 3.

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