Rear vehicle safety securing device and rear vehicle safety securing method

Abstract

To provide a rear vehicle safety securing device and a rear vehicle safety securing method capable of preventing a rear vehicle from being stalled within a dangerous area behind an own vehicle even when the own vehicle cannot move forward.SOLUTION: A rear vehicle safety securing device 1 includes: a measurement section 3 for measuring a distance between an object and a rear end of an own vehicle in a case where there is the object indicating a predetermined dangerous area, the predetermined dangerous area being an area where it is dangerous for a rear vehicle to stop behind the own vehicle when the own vehicle stops on a travel route; and a determination section 5 for determining, based on the distance measured by the measurement section 3, whether the rear vehicle can move so as to be settled within a space between the dangerous area and the own vehicle. The rear vehicle safety securing device 1 is mounted on the own vehicle and further includes a notification section 7 for notifying the rear vehicle of whether the rear vehicle can move so as to be settled within the space based on the determination of the determination section 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a safety ensuring device for a following vehicle and a safety ensuring method for a following vehicle.

Background Art

[0002] On a vehicle's traveling road, there are areas that intersect with passageways where pedestrians and other vehicles pass, such as crosswalks, railroad crossings, and intersections. This area can be traveled when the intersecting passageways are not in use by pedestrians or other vehicles, or when traffic control devices such as traffic lights or barriers give an indication that it is possible to proceed. However, stopping within this area obstructs the passage of pedestrians and other vehicles using the intersecting passageways and can also cause accidents such as collisions. Therefore, this area is a dangerous area where stopping is not preferred.

[0003] When the traffic on the traveling road including the dangerous area is congested and the distance between the host vehicle and the vehicle ahead becomes short, the host vehicle may stop immediately after passing through the dangerous area in order to avoid contact with the vehicle ahead. In this case, a space where no following vehicle exists is created on the traveling road between the host vehicle and the dangerous area. If this space is sufficiently longer than the vehicle length of the following vehicle, even if the following vehicle enters the dangerous area after the host vehicle stops, the following vehicle can pass through the dangerous area and stop within the space. On the other hand, if the space is not sufficiently longer than the vehicle length of the following vehicle, when the following vehicle enters the dangerous area, the rear end of the following vehicle may protrude into the dangerous area and stop, and there is a possibility that the following vehicle will be stuck within the dangerous area. Therefore, when the length of the space between the host vehicle and the dangerous area is insufficient for the following vehicle to stop, a technique of expanding the space by moving the host vehicle forward has been proposed (see, for example, Patent Documents 1 to 3). As described above, the conventional technology assumes the case where the following vehicle enters the dangerous area behind the host vehicle, and secures a space between the host vehicle and the dangerous area so that the following vehicle can stop outside the dangerous area by moving the host vehicle forward.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technologies of Patent Documents 1 to 3, when a following vehicle enters the dangerous area behind the host vehicle and the distance between the host vehicle and the preceding vehicle is not sufficient for the host vehicle to move forward, the host vehicle cannot move forward, and the space between the host vehicle and the dangerous area cannot be widened. In this case, the following vehicle may not be able to move forward from within the dangerous area and may stop, and there is a risk of being stuck within the dangerous area.

[0006] The present invention has been made to solve such problems, and an object thereof is to provide a safety ensuring device for a following vehicle and a safety ensuring method for a following vehicle that can prevent the following vehicle from being stuck within the dangerous area behind the host vehicle even when the host vehicle cannot move forward.

Means for Solving the Problems

[0007] The safety ensuring device for a following vehicle of the present invention, when the host vehicle stops on a road, if there is an object indicating a dangerous area that is predetermined to be dangerous when a following vehicle stops behind the host vehicle, a measuring means for measuring the distance between the object and the rear end of the host vehicle, and a judging means for judging whether the following vehicle can move so as to fit within the space between the dangerous area and the host vehicle based on the distance measured by the measuring means, and the safety ensuring device for a following vehicle mounted on the host vehicle, further comprising a notifying means for notifying the following vehicle whether the following vehicle can move so as to fit within the space based on the judgment of the judging means.

[0008] The method for ensuring the safety of a following vehicle according to the present invention includes a measuring step of measuring the distance between an object indicating a dangerous area, which is predetermined to be dangerous when a following vehicle stops behind the host vehicle when the host vehicle stops on a road, and the rear end of the host vehicle, and a determining step of determining whether the following vehicle can move so as to fit within the space between the dangerous area and the host vehicle based on the distance measured in the measuring step. The method for ensuring the safety of a following vehicle further includes a notifying step of notifying the following vehicle whether it can move so as to fit within the space based on the determination in the determining step.

Effect of the Invention

[0009] According to the present invention, it is possible to provide a safety ensuring device and a safety ensuring method for a following vehicle that can prevent the following vehicle from being stuck within a dangerous area behind the host vehicle even when the host vehicle cannot be advanced.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0011] Hereinafter, the present invention will be described along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be appropriately modified without departing from the gist of the present invention. Also, in the embodiments shown below, there are some places where the illustration and description of some configurations are omitted. However, it goes without saying that well-known or widely known technologies are appropriately applied within the range where there is no contradiction with the content described below regarding the details of the omitted technologies.

[0012] First, the first embodiment will be described with reference to FIGS. 1 to 8. First, an outline of the configuration of a following-vehicle safety ensuring device according to the first embodiment will be described. FIG. 1 is a configuration diagram showing a following-vehicle safety ensuring device according to the first embodiment. The following-vehicle safety ensuring device 1 is a device that notifies a following vehicle whether the following vehicle can move so as to fit within the space between a dangerous area and the host vehicle when there is a dangerous area behind the host vehicle when the host vehicle stops on a road. The following-vehicle safety ensuring device 1 shown in FIG. 1 is mounted on the host vehicle and includes a measurement unit 3 (measurement means), a determination unit 5 (determination means), and a notification unit 7 (notification means).

[0013] For example, as shown in FIG. 2, in a road section 11 where the traveling direction is traveling direction A indicated by the white arrow, assume that the host vehicle 13 has stopped due to reasons such as the inter-vehicle distance from the preceding vehicle becoming short after passing through the danger area 15. Further, assume that a following vehicle 21 is traveling in a traveling area 23 in front of the danger area 15 from behind the host vehicle 13 on the road section 11 and is about to enter the danger area 15. Here, the danger area 15 is an area that is predefined to be dangerous if the following vehicle 21 stops behind the host vehicle 13 when the host vehicle 13 stops on the road section 11. In this case, if the length of the space 25a between the host vehicle 13 and the danger area 15 in the traveling direction A is sufficiently longer than the vehicle length of the following vehicle 21, the following vehicle 21 that has entered the danger area 15 can pass through the danger area 15 and stop within the space 25a. On the other hand, if the length of the space 25a is not sufficiently longer than the vehicle length of the following vehicle 21, the following vehicle 21 that has entered the danger area 15 cannot fit within the space 25a and will stop with the rear end of the vehicle protruding into the danger area 15. Therefore, the safety assurance device 1 for the following vehicle 21 measures the distance 25 between the object 17 indicating the danger area 15 and the rear end of the host vehicle by the measuring unit 3. Further, the determination unit 5 determines whether the following vehicle 21 can move so as to fit within the space 25a based on the measurement result, and the notification unit 7 notifies the following vehicle 21 of the determination result. Therefore, when the space 25a between the danger area 15 and the host vehicle 13 is too short and there is a possibility that the following vehicle 21 may become stuck within the danger area 15 if it moves forward, the unnecessary forward movement of the following vehicle 21 can be stopped. Thus, even when the space 25a between the host vehicle 13 and the danger area 15 cannot be widened by the forward movement of the host vehicle 13, an accident caused by the following vehicle 21 becoming stuck in the danger area 15 can be prevented. The above is an explanation of the outline of the configuration of the safety assurance device 1 for the following vehicle 21 according to the first embodiment.

[0014] Next, the details of the configurations of the measurement unit 3, the determination unit 5, and the notification unit 7 will be described. The measurement unit 3 shown in FIG. 1 measures the distance 25 between the object 17 located at the front end of the danger area 15 shown in FIG. 2 and the rear end of the host vehicle. The object 17 indicates the danger area 15 and is located at the front end of the danger area 15 in FIG. 2. In this way, by measuring the distance 25 between the object 17 and the rear end of the host vehicle without directly obtaining the length of the space 25a, an object 17 with an easily detectable shape and dimensions can be selected, and the measurement accuracy of the length of the space 25a can be improved. In FIG. 2, since the front end of the object 17 protrudes in front of the danger area 15, the distance 25 between the object 17 and the rear end of the host vehicle is not exactly the same as the length of the space 25a between the danger area 15 and the rear end of the host vehicle. However, if the distance 25 is shorter than the space 25a, there is no risk that the determination unit 5 will make an incorrect determination that the rear vehicle 21 can move so as to fit within the space 25a. Also, if it is desired to accurately measure the length of the space 25a, the difference between the distance 25 and the space 25a may be obtained in advance, and the distance 25 may be corrected using the obtained difference to obtain the length of the space 25a.

[0015] The measurement unit 3 shown in FIG. 1 is configured to receive a travel pulse signal PS indicating the number of travel pulses generated by a vehicle speed sensor (not shown) of the host vehicle 13. The measurement unit 3 shown in FIG. 1 obtains the distance 25 between the object 17 and the rear end of the host vehicle from the travel pulse signal PS. Specifically, the measurement unit 3 measures the distance 25 from the difference between the number of travel pulses generated by the vehicle speed sensor of the host vehicle 13 when the host vehicle 13 passes the object 17 and the number of travel pulses generated by the vehicle speed sensor when the host vehicle 13 stops after passing the object 17. The moving distance at the time of one pulse input varies depending on the vehicle speed and vehicle settings. For example, an example of the moving distance at the time of one pulse input for a vehicle traveling at a speed of 60 km / h is 1000 m÷(637 (number of rotations)×8 pulses (number of pulses generated by the vehicle speed sensor)) = 0.19 m. However, the number of rotations and the number of pulses generated by the vehicle speed sensor vary depending on the vehicle. In this way, the measurement unit 3 measures the distance 25 from the difference in the number of pulses from when the host vehicle 13 passes the object 17 until it stops. Therefore, the distance 25 can be obtained from the number of travel pulses generated by the existing vehicle speed sensor of the host vehicle 13, and there is no need to separately provide a device for distance measurement. Also, since the number of travel pulses generated by the vehicle speed sensor is usually an integrated value, the distance 25 can be measured from the difference in the number of travel pulses. Therefore, it is also advantageous that a counter for counting the number of travel pulses from when the host vehicle 13 passes the object 17 until it stops is not required. Note that the means for measuring the distance 25 is not limited to the difference in the number of travel pulses, so the distance 25 may be measured by counting the number of pulses from when the host vehicle 13 passes the object 17 until it stops. However, in the following description, the first embodiment will be described by taking the case of using the number of travel pulses as an example.

[0016] The measurement unit 3 shown in FIG. 1 is configured such that an image captured by a front camera 3a installed in the host vehicle 13 and imaging the front of the host vehicle 13 is input. In this configuration, the measurement unit 3 detects the object 17 from the video in front of the host vehicle 13 captured by the front camera 3a before the host vehicle 13 passes the object 17, using known image analysis means such as edge extraction. Thereafter, the distance is measured by assuming that the point where the object 17 disappears from the imaging range in the video captured by the front camera 3a is the point where the object 17 is installed. In this way, the measurement unit 3 measures the distance 25 based on the video captured by the front camera 3a. Therefore, a camera for existing in-vehicle devices such as a digital tachometer or a drive recorder can be used to determine whether the host vehicle 13 has passed the object 17, saving the trouble and cost of newly installing a camera in the host vehicle 13. Since the front camera 3a is usually installed at the front end of the host vehicle 13, when the detection distance from when the host vehicle 13 passes the object 17 until it stops is obtained using the front camera 3a, the value becomes L1 in FIG. 2. Therefore, the measurement unit 3 obtains the distance 25 by subtracting L2, which is the vehicle length of the host vehicle 13, from L1.

[0017] Specific examples of the danger area 15 and the object 17 are as follows. FIGS. 3 to 7 are diagrams showing examples of the danger area 15 and the object 17. As shown in FIG. 3, the crosswalk 31 can be exemplified as the danger area 15. When the danger area 15 is the crosswalk 31, the object 17 is the front end 33 of the crosswalk 31 in the traveling direction A of the host vehicle 13. In this case, within the traveling road 11, the measurement unit 3 measures the distance 25 (which is the same as the length of the space 25a in this case) between the front end 33 of the crosswalk 31 and the host vehicle 13. Further, the determination unit 5 determines whether the rear vehicle 21 can move within the space 25a, and the notification unit 7 issues a notification. Therefore, when the space 25a is too short for the rear vehicle 21 to stop, it is possible to prevent the rear vehicle 21 from advancing forcibly and getting stuck at the crosswalk 31, which would obstruct the crossing of the pedestrian 35, and ensure the safety of the pedestrian 35.

[0018] As shown in Fig. 4, a level crossing 39 can also be exemplified as the dangerous area 15. When the dangerous area 15 is the level crossing 39, the object 17 is a barrier 41 provided at the front end of the level crossing 39 in the traveling direction A of the host vehicle 13. When the dangerous area 15 is the level crossing 39, the safety ensuring device 1 of the following vehicle 21 measures, in the traveling road 11, the distance 25 between the barrier 41 of the level crossing 39 and the host vehicle 13 by the measuring unit 3, and the determination unit 5 determines whether the following vehicle 21 can move into the space 25a, and the notification unit 7 performs notification. Therefore, when the space 25a is too short for the following vehicle 21 to stop, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the level crossing 39 and obstructing the travel of a railway vehicle (not shown), and the safety of the following vehicle 21 and the railway vehicle can be ensured.

[0019] As shown in Fig. 5, an intersection 43 where a traffic signal 45 is installed can also be exemplified as the dangerous area 15. When the dangerous area 15 is the intersection 43 where the traffic signal 45 is installed, the object 17 is the traffic signal 45 that organizes the traffic of vehicles in the traveling direction A passing through the traveling road 11. When the dangerous area 15 is the intersection 43, the safety ensuring device 1 of the following vehicle 21 measures, in the traveling road 11, the distance 25 between the traffic signal 45 and the host vehicle 13 by the measuring unit 3, and the determination unit 5 determines whether the following vehicle 21 can move into the space 25a, and the notification unit 7 performs notification. Therefore, when the space 25a is too short for the following vehicle 21 to stop, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the intersection 43 and obstructing the travel of the vehicles traveling on the intersecting roads, and the safety of the following vehicle 21 and the vehicles traveling on the intersecting roads can be ensured. Note that since the traffic signal 45 may be installed at a location other than the intersection 43, for example, at the pedestrian crossing 31 shown in Fig. 3, just because the traffic signal 45 is detected, it is not always the case that there is an intersection 43 at the detection point. Therefore, it may be separately determined from the video imaged by the front camera 3a whether the detection point is the intersection 43. On the other hand, since the area in front of the location where the vehicle traffic signal 45 is installed is the dangerous area 15 whether it is the pedestrian crossing 31 or the intersection 43, it is not always necessary to specify the specific type of the dangerous area 15 when the traffic signal 45 is detected.

[0020] As shown in FIG. 6, an intersection 47 where a traffic signal 45 is not installed can also be exemplified as a dangerous area 15. When the dangerous area 15 is the intersection 47 where the traffic signal 45 is not installed, the object 17 is the frontmost lane 51 in the traveling direction A among the lanes of the road intersecting with the traveling road 11 at the intersection 47. When the dangerous area 15 is the intersection 47 where the traffic signal 45 is not installed, the measurement unit 3 first detects the lane 49 (the center line 49a or the left roadside strip 49b in FIG. 6) indicating the traveling road 11 on which the host vehicle 13 travels and the lane 51. After that, when the lane 49 is once interrupted at the intersection 47 and the lane 51 of the road intersecting with the traveling road 11 at the intersection 47 goes out of the detection range, it is determined that the host vehicle 13 has passed through the lane 51 as the object 17. Therefore, in this case, the lane 49 is used to detect the object 17. In this way, when the dangerous area 15 is the intersection 47 where the traffic signal 45 is not installed, the measurement unit 3 measures the distance 25 between the lane 51 intersecting at the intersection 47 and the host vehicle 13 within the traveling road 11. Further, the determination unit 5 determines whether the following vehicle 21 can move within the space 25a, and the notification unit 7 performs the notification. Therefore, when the space 25a is too short for the following vehicle 21 to stop, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the intersection 47 and obstructing the travel of the traveling vehicles on the intersecting road, and the safety of the following vehicle 21 and the traveling vehicles on the intersecting road can be ensured. Also, by setting the lane 51 as the object 17 by the measurement unit 3, the distance 25 can be obtained even at the intersection 47 where there is no prominent object 17 such as a traffic signal 45 or the front end 33 of a crosswalk 31.

[0021] As shown in FIG. 7, an intersection 53 where a traffic signal 45 and a crosswalk 31 are installed can also be exemplified as a dangerous area 15. At the intersection 53, the object 17 is the front end 33 of the crosswalk 31 and the traffic signal 45. Therefore, when obtaining the distance 25, the front end 33 of the crosswalk 31 or the traffic signal 45 may be used as the object 17. However, when both the front end 33 of the crosswalk 31 and the traffic signal 45 are detected by the measurement unit 3, it is preferable to prioritize the front end 33 of the crosswalk 31 as the object 17. In this way, when a plurality of objects 17 including the front end 33 of the crosswalk 31 are detected, by prioritizing the front end 33 of the crosswalk 31 as the object 17, the safety of the pedestrian 35 can be ensured with priority over the safety of the following vehicle 21 and the vehicles traveling on the intersecting road.

[0022] The determination unit 5 shown in FIG. 1 is a means for determining whether the following vehicle 21 can move so as to be within the space 25a between the dangerous area 15 and the host vehicle 13 based on the distance 25 measured by the measurement unit 3. Specifically, for example, when the distance 25 is longer than a predetermined set value (first set value), the determination unit 5 determines that the following vehicle 21 can move so as to be within the space 25a. When the distance 25 is less than the predetermined set value, it is determined that there is a possibility that the following vehicle 21 cannot move so as to be within the space 25a. The predetermined set value is, for example, a value obtained by adding a vehicle-to-vehicle distance that does not contact the vehicle in front to the vehicle length of the vehicle assumed as the following vehicle 21, and it is preferably possible for the driver of the host vehicle 13 to set it. For example, the vehicle length is different when the following vehicle 21 is a passenger car and when it is a freight vehicle such as a truck. Therefore, for example, when traveling on a road 11 where only passenger cars travel, the set value may be the vehicle length of a passenger car, and when traveling on a road 11 where only freight vehicles travel, the set value may be the vehicle length of a truck.

[0023] The notification unit 7 shown in FIG. 1 is a means for notifying the following vehicle 21 whether it can move so as to fit within the space 25a based on the determination of the determination unit 5. As specific notification content, when the determination unit 5 determines that the following vehicle 21 can move so as to fit within the space 25a, the notification unit 7 issues a notification to the following vehicle 21 to prompt passage through the danger area 15. Also, when the determination unit 5 determines that there is a possibility that the following vehicle 21 cannot move so as to fit within the space 25a, the notification unit 7 issues a notification to the following vehicle 21 to stop passage through the danger area 15. By issuing a notification to prompt passage or a notification to stop passage through the danger area 15 in this way, the notification unit 7 can specifically inform the driver of the following vehicle 21 what kind of driving should be done. As specific notification means, as shown in FIG. 1, an electric bulletin board 7a provided at the rear end of the vehicle or means for displaying, in characters, a notification to prompt passage or a notification to stop passage through the danger area 15 on a rear display board (not shown) can be exemplified. Also, using a communication unit 7b such as a wireless transmitter provided in the host vehicle 13, a vehicle-to-vehicle communication can be used to transmit a notification to prompt passage or a notification to stop passage through the danger area 15 to the digital tachometer of the following vehicle 21 or the communication unit 9 which is a communication terminal. In this case, the content of the notification may be transmitted as voice through a speaker (not shown) provided in the driver's seat of the following vehicle 21. Or the notification may be displayed in characters on a display unit (not shown) provided in the driver's seat of the following vehicle 21. Furthermore, the communication unit 9 of the following vehicle 21 includes a mobile communication device such as a smartphone instead of an in-vehicle device. Also, the standard of wireless communication is not particularly limited, and a standard such as Bluetooth (registered trademark) may be used.

[0024] However, the notification unit 7 does not necessarily always need to notify the following vehicle 21 when the determination unit 5 determines that the following vehicle 21 can move so as to fit within the space 25a. For example, the notification unit 7 may notify the following vehicle 21 whether it can move so as to fit within the space 25a only when the distance 25 measured by the measurement unit 3 is less than a predetermined distance (second set value). The predetermined distance is, for example, a distance such that the driver of the following vehicle 21 can determine whether the following vehicle 21 can move so as to fit within the space 25a. When the space 25a is long enough for the following vehicle 21 to clearly understand that there is no risk of being stuck even if the following vehicle 21 enters the danger area 15, the notification unit 7 may not need to notify. As a result, when the following vehicle 21 can determine that it can move so as to fit within the space 25a, unnecessary notifications can be avoided, and the man-hours and costs associated with the notifications can be reduced. Note that the determination as to whether to notify may be made by the determination unit 5 or the notification unit 7.

[0025] In addition, the safety assurance device 1 for the following vehicle 21 shown in FIG. 1 may be realized by storing a program that realizes the functions of the measurement unit 3, the determination unit 5, and the notification unit 7 in the storage unit of a general-purpose computer and causing the central processing unit of the general-purpose computer to execute each program. Alternatively, the safety assurance device 1 for the following vehicle 21 may be realized as a dedicated machine using an integrated circuit that realizes the functions of the measurement unit 3, the determination unit 5, and the notification unit 7, such as a so-called embedded system.

[0026] Next, a method for ensuring the safety of the rear vehicle 21 using the safety assurance device 1 for the rear vehicle 21 according to the first embodiment will be described. First, the outline of the safety assurance method will be described. The method for ensuring the safety of the rear vehicle 21 includes a measurement step of measuring the distance 25 between the object 17 located at the front end of the danger area 15 and the rear end of the host vehicle, and a determination step of determining whether the rear vehicle 21 can move so as to fit within the space 25a based on the distance 25 measured in the measurement step. The method for ensuring the safety of the rear vehicle 21 further includes a notification step of notifying the rear vehicle 21 whether it can move so as to fit within the space 25a based on the determination in the determination step. In this way, in the method for ensuring the safety of the rear vehicle 21, the rear vehicle 21 is notified whether it can move so as to fit within the space 25a. Therefore, even when the space 25a between the host vehicle 13 and the danger area 15 cannot be expanded by the forward movement of the host vehicle 13, it is possible to prevent the rear vehicle 21 from getting stuck in the danger area 15. The above is the description of the outline of the configuration of the safety assurance device 1 for the rear vehicle 21 according to the first embodiment.

[0027] Next, the details of the safety assurance method will be described. FIG. 8 is a flowchart showing the details of the method for ensuring the safety of the rear vehicle 21 using the safety assurance device 1 for the rear vehicle 21 according to the first embodiment. First, it is assumed that the host vehicle 13 is traveling on the road 11. In this case, the measurement unit 3 images the front of the host vehicle 13 using the front camera 3a. Further, the measurement unit 3 determines whether an object 17 or the like has been detected from the captured image by known image analysis or the like. If detected, the process proceeds to S2-1. If not detected, this process is repeated (S1 in FIG. 8). Note that the "object 17 or the like" referred to in S1 includes the object 17 and the lane 49 of the road 11 when the object 17 intersects the lane 51 at the intersection 53 with the road 11.

[0028] When it is determined in S1 that an object 17 or the like has been detected, the measurement unit 3 determines whether the object 17 or the like is at the front end 33 of the crosswalk 31. If it is at the front end 33, the process proceeds to S3-1. If it is not at the front end 33, the process proceeds to S2-2 (S2-1 in FIG. 8). When it is determined in S2-1 that the object 17 or the like is at the front end 33, the measurement unit 3 determines whether the front end 33 has gone out of the detection range of the front camera 3a, specifically, whether it has disappeared from the video. As a result, if it is determined that it has gone out of the detection range, the process proceeds to S4. If it is determined that it has not gone out of the detection range, this process is repeated (S3-1 in FIG. 8). When it is determined in S2-1 that the object 17 or the like is not at the front end 33, the measurement unit 3 determines whether the object 17 or the like is the barrier 41 of the level crossing 39. If it is determined that it is the barrier 41, the process proceeds to S3-2. If it is determined that it is not the barrier 41, the process proceeds to S2-3 (S2-2 in FIG. 8). When it is determined in S2-2 that the object 17 or the like is the barrier 41, the measurement unit 3 determines whether the barrier 41 has gone out of the detection range of the front camera 3a. If it is determined that it has gone out of the detection range, the process proceeds to S4. If it is determined that it has not gone out of the detection range, this process is repeated (S3-2 in FIG. 8). When it is determined in S2-2 that the object 17 or the like is not the barrier 41, the measurement unit 3 determines whether the object 17 or the like is the traffic signal 45. If it is determined that it is the traffic signal 45, the process proceeds to S3-3. If it is determined that it is not the traffic signal 45, the process proceeds to S2-4 (S2-3 in FIG. 8). Note that since S2-3 is a step of determining whether the dangerous area 15 is the intersection 43 where the traffic signal 45 is located, not only the presence or absence of the traffic signal 45 but also the presence of the intersection 43 may be determined together.

[0029] When it is determined in S2-3 that the object 17 or the like is the traffic signal 45, the measurement unit 3 determines whether the traffic signal 45 has gone out of the detection range of the front camera 3a. If it is determined that it has gone out of the detection range, the process proceeds to S4. If it is determined that it has not gone out of the detection range, this process is repeated (S3-3 in FIG. 8). When it is determined in S2-3 that the object 17 or the like is not the traffic signal 45, the measurement unit 3 determines whether the object 17 or the like is the lane 49 and the lane 51. Specifically, it is determined whether the object 17 or the like is the lane 49 (the lane whose front is cut off at the intersection 47) and the lane 51 at the intersection 47 where there is no traffic signal 45. In this case, it may also be determined whether there is an intersection 47 ahead. If it is determined that they are the lane 49 and the lane 51, the process proceeds to S3-4. If it is determined that they are not the lane 49 and the lane 51, the process returns to S1 (S2-4 in FIG. 8). When it is determined in S2-4 that the object 17 or the like is the lane 49 and the lane 51, the measurement unit 3 determines whether the lane 49 of the traveling road 11 has gone out of the detection range of the front camera 3a (whether it has been cut off once at the intersection 47). As a result, if it is determined that it has gone out of the detection range, the process proceeds to S3-5. If it is determined that it has not gone out of the detection range, this process is repeated (S3-4 in FIG. 8). When it is determined in S3-4 that the lane 49 has gone out of the detection range of the front camera 3a, the measurement unit 3 determines whether the lane 51 has gone out of the detection range. If it is determined that it has gone out of the detection range, the process proceeds to S4. If it is determined that it has not gone out of the detection range, this process is repeated (S3-5 in FIG. 8).

[0030] When the process shifts to S4, since the measurement unit 3 assumes (estimates) the location where the object 17 is installed, the measurement unit 3 acquires the travel pulse signal PS and records the number of travel pulses at the location where the object 17 is assumed to be installed (S4 in FIG. 8). Next, the measurement unit 3 determines whether the host vehicle 13 has stopped by acquiring the vehicle speed of the host vehicle 13 from a vehicle speed sensor (not shown), etc. If it is determined that the vehicle has stopped, the process proceeds to S6. If it is determined that the vehicle has not stopped, this process is repeated (S5 in FIG. 8). When it is determined in S5 that the host vehicle 13 has stopped, the measurement unit 3 acquires the travel pulse signal PS and records the number of travel pulses at the time of stopping. Further, the measurement unit 3 subtracts the number of pulses acquired in S4 from the number of travel pulses acquired when the host vehicle 13 has stopped to obtain the difference in the number of pulses, calculates the distance 25 from the obtained difference, and proceeds to S7 (S6 in FIG. 8, measurement step). In S7, the determination unit 5 determines whether the distance 25 (difference in the number of pulses) is greater than the first set value. If it is determined that the distance 25 is greater than the first set value, the process proceeds to S9. If it is determined that the distance 25 is not greater than the first set value, the process proceeds to S12 (S7 in FIG. 8, determination step).

[0031] When it is determined in S7 that the distance 25 is not greater than the first set value, there is a possibility that the following vehicle 21 may not fit within the space 25a. Therefore, the determination unit 5 instructs the notification unit 7 to issue a notification to the following vehicle 21 to stop passing. The notified notification unit 7 issues a notification to the following vehicle 21 to stop passing (S12 in FIG. 8, notification step). When it is determined in S7 that the distance 25 is greater than the first set value, the determination unit 5 determines whether the distance 25 (the difference in the number of pulses) is less than the second set value. If it is determined that the distance 25 is less than the second set value, the process proceeds to S10. If it is determined that the distance 25 is not less than the second set value, the process proceeds to S11 (S9 in FIG. 8). When it is determined in S9 that the distance 25 is less than the second set value, the determination unit 5 instructs the notification unit 7 to issue a notification to the following vehicle 21 to urge passing. The notified notification unit 7 issues a notification to the following vehicle 21 to urge passing (S10 in FIG. 8, notification step). When it is determined in S9 that the distance 25 is not less than the second set value, the determination unit 5 returns without instructing the notification unit 7 to issue a notification to the following vehicle 21 (S11 in FIG. 8). The above is a detailed description of the method for ensuring the safety of the following vehicle 21 using the safety ensuring device 1 for the following vehicle 21 according to the first embodiment.

[0032] As described above, the safety ensuring device 1 for the following vehicle 21 according to the first embodiment notifies the following vehicle 21 whether it can move so as to fit within the space 25a between the own vehicle 13 and the danger area 15 when the own vehicle 13 stops after passing through the danger area 15. Therefore, when the space 25a between the danger area 15 and the own vehicle 13 is too short and there is a possibility that the following vehicle 21 may be trapped within the danger area 15 if it advances, the forced advance of the following vehicle 21 can be stopped. Thus, even when the space 25a between the own vehicle 13 and the danger area 15 cannot be widened by the advance of the own vehicle 13, an accident due to the following vehicle 21 being trapped within the danger area 15 can be prevented. Further, even when the own vehicle 13 is a large cargo vehicle such as a truck and the following vehicle 21 feels uneasy about whether it can pass through the danger area 15 because its forward view is blocked by the own vehicle 13, the notification unit 7 notifies whether passing is possible, so the uneasiness is resolved.

[0033] Also, in the first embodiment, the measurement unit 3 measures the distance 25 from the difference between the number of travel pulses generated by the vehicle speed sensor of the host vehicle 13 when the host vehicle 13 passes the object 17 and the number of travel pulses generated by the vehicle speed sensor when the host vehicle 13 stops after passing the object 17. Therefore, the distance 25 can be obtained from the number of travel pulses generated by the existing vehicle speed sensor in the host vehicle 13, and there is no need to separately provide a device for distance measurement. Further, since the number of travel pulses generated by the vehicle speed sensor is usually an integrated value, the distance 25 can be measured from the difference in the number of travel pulses. Therefore, a counter for counting the number of travel pulses from when the host vehicle 13 passes the object 17 until it stops becomes unnecessary.

[0034] Furthermore, in the first embodiment, the measurement unit 3 detects the object 17 with the front camera 3a before the host vehicle 13 passes the object 17, and measures the distance assuming that the point where the object 17 disappears from the imaging range of the front camera 3a is the point where the object 17 is installed. Therefore, a camera for in-vehicle equipment existing in a digital tachometer, a drive recorder, etc. can be used as the front camera 3a, saving the trouble and cost of newly installing a camera.

[0035] On the other hand, in the first embodiment, the danger area 15 is the pedestrian crossing 31, and the object 17 is the front end 33 in the traveling direction A of the pedestrian crossing 31. In this configuration, within the traveling road 11, the determination unit 5 determines whether the rear vehicle 21 can move within the space 25a between the front end 33 of the pedestrian crossing 31 and the host vehicle 13, and the notification unit 7 issues a notification. Therefore, when the space 25a is too short, it is possible to prevent the rear vehicle 21 from advancing forcibly and getting stuck at the pedestrian crossing 31, which would obstruct the crossing of the pedestrian 35, and ensure the safety of the pedestrian 35.

[0036] Also, in the first embodiment, the danger area 15 is the level crossing 39, and the object 17 is the barrier 41 provided at the front end of the level crossing 39 in the traveling direction A. In this configuration, within the road 11, the determination unit 5 determines whether the following vehicle 21 can move within the space 25a between the barrier 41 of the level crossing 39 and the host vehicle 13, and the notification unit 7 issues a notification. Therefore, when the space 25a is too short, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the level crossing 39 and obstructing the travel of the railway vehicle, and the safety of the following vehicle 21 and the railway vehicle can be ensured.

[0037] Furthermore, in the first embodiment, the danger area 15 is the intersection 43 where the traffic signal 45 is installed, and the object 17 is the traffic signal 45. In this configuration, within the road 11, the determination unit 5 determines whether the following vehicle 21 can move within the space 25a between the traffic signal 45 of the intersection 43 and the host vehicle 13, and the notification unit 7 issues a notification. Therefore, when the space 25a is too short, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the intersection 43 and obstructing the travel of the vehicles on the intersecting road, and the safety of the following vehicle 21 and the vehicles on the intersecting road can be ensured.

[0038] On the other hand, in the first embodiment, the danger area 15 is the intersection 47 where the traffic signal 45 is not installed, and the object 17 is the lane 51 at the front end in the traveling direction A of the host vehicle 13 among the lanes intersecting the road 11 at the intersection 47. In this configuration, the determination unit 5 determines whether the following vehicle 21 can move within the space 25a between the lane 51 intersecting the road 11 at the intersection 47 and the host vehicle 13, and the notification unit 7 issues a notification. Therefore, when the space 25a is too short, it is possible to prevent the following vehicle 21 from advancing forcibly and getting stuck within the intersection and obstructing the travel of the vehicles on the intersecting road, and the safety of the following vehicle 21 and the vehicles on the intersecting road can be ensured. Also, even at the intersection 47 where there is no prominent object 17 such as the traffic signal 45 or the pedestrian crossing 31, the distance 25 can be obtained.

[0039] Also, in the first embodiment, the dangerous area 15 is the intersection 53 where the crosswalk 31 and the traffic signal 45 are installed, and the object 17 is the front end 33 of the crosswalk 31 and the traffic signal 45. Further, the measuring unit 3 prioritizes the front end 33 of the crosswalk 31 as the object 17. In this configuration, when both the traffic signal 45 and the front end 33 of the crosswalk 31 are detected, the front end 33 of the crosswalk 31 is prioritized as the object 17, so that the safety of the pedestrian 35 can be ensured with priority over the safety of the vehicle.

[0040] Furthermore, in the first embodiment, when the determination unit 5 determines that the rear vehicle 21 can move so as to fit within the space 25a, the notification unit 7 gives a notification to the rear vehicle 21 to prompt passage through the dangerous area 15. When the determination unit 5 determines that there is a possibility that the rear vehicle 21 cannot move so as to fit within the space 25a, the notification unit 7 gives a notification to the rear vehicle 21 to stop passage through the dangerous area 15. In this way, when the determination unit 5 determines that the rear vehicle 21 can move so as to fit within the space 25a, the notification unit 7 gives a notification to prompt passage, and when there is a possibility that it cannot move, gives a notification to stop passage, thereby specifically informing the driver of the rear vehicle 21 of what kind of driving should be done.

[0041] On the other hand, in the first embodiment, the notification unit 7 notifies the rear vehicle 21 whether it can move so as to fit within the space 25a only when the distance 25 measured by the measuring unit 3 is less than a predetermined distance. In this configuration, when the space 25a is long enough for the rear vehicle 21 to clearly understand that there is no risk of being stuck even if it enters the dangerous area 15, the notification unit 7 does not give a notification. Therefore, when the rear vehicle 21 can determine that it can move so as to fit within the space 25a, unnecessary notifications can be avoided, and the man-hours and costs related to the notifications can be reduced.

[0042] Moreover, the method for ensuring the safety of the rear vehicle 21 according to the first embodiment includes a measuring step of measuring the distance 25 between the object 17 and the rear end of the host vehicle, and a determining step of determining whether the rear vehicle 21 can move so as to fit within the space 25a based on the distance 25 measured in the measuring step. The method for ensuring the safety of the rear vehicle 21 according to the first embodiment further includes a notifying step of notifying the rear vehicle 21 whether it can move so as to fit within the space 25a based on the determination in the determining step. In this way, in the method for ensuring the safety of the rear vehicle 21, the rear vehicle 21 is notified whether it can move so as to fit within the space 25a. Therefore, even when the space 25a between the host vehicle 13 and the danger area 15 cannot be expanded by the forward movement of the host vehicle 13, an accident caused by the rear vehicle 21 being stuck in the danger area 15 can be prevented.

[0043] Next, a second embodiment will be described with reference to FIGS. 9 and 10. In the second embodiment, in the first embodiment, instead of the front camera 3a, the object 17 is detected using a rear camera 3b that images the rear of the host vehicle 13. Note that in the second embodiment, elements that perform the same functions as those in the first embodiment are given the same numbers, and mainly the differences from the first embodiment will be described.

[0044] First, the configuration of the safety assurance device for the rear vehicle 21 according to the second embodiment will be described. FIG. 9 is a configuration diagram showing the safety assurance device 1a for the rear vehicle 21 according to the second embodiment. As shown in FIG. 9, the measurement unit 3 of the safety assurance device 1a for the rear vehicle 21 is configured to acquire the video imaged by the rear camera 3b. The rear camera 3b is a camera that images the rear of the host vehicle 13 and is usually provided at the rear end of the host vehicle 13. In the second embodiment, the measurement unit 3 measures the distance 25 by assuming that the point where the object 17 is displayed on the rear camera 3b is the point where the object 17 is installed. In this way, the distance 25 may be measured based on the video imaged by the rear camera 3b. Since the rear camera 3b can image not only the object 17 but also the rear vehicle 21, the presence or absence and the vehicle type of the rear vehicle 21 can also be determined from the video. Therefore, the safety assurance device 1a for the rear vehicle 21 can make determinations and notifications according to the actual rear situation of the host vehicle 13.

[0045] For example, the determination unit 5 may be configured to receive the video captured by the rear camera 3b. In this case, the presence or absence of the rear vehicle 21 can be detected from the input video. Further, when the rear vehicle 21 is detected from the video captured by the rear camera 3b, the determination unit 5 can also identify the vehicle type. Furthermore, the determination unit 5 can determine whether the rear vehicle 21 can move so as to fit within the space 25a between the danger area 15 and the host vehicle 13 based on the identified vehicle type. By using the image captured by the rear camera 3b in this way, it is possible to specifically determine whether the rear vehicle 21 can move so as to fit within the space 25a according to the vehicle length of the rear vehicle 21, and thus the accuracy of the determination can be improved.

[0046] For example, since the vehicle lengths of a passenger car and a truck are different, even if the distance 25 measured by the measurement unit 3 is sufficient for the passenger car to move, it may be insufficient for the truck to move. Therefore, when the distance 25 measured by the measurement unit 3 is longer than a set value (first set value) predetermined for each vehicle type, the determination unit 5 may determine that the rear vehicle 21 can move so as to fit within the space 25a. That is, the first set value may vary according to the vehicle type. In this configuration, the determination unit 5 compares the first set value corresponding to the vehicle type of the rear vehicle 21 with the distance 25 measured by the measurement unit 3 to determine whether the rear vehicle 21 can move within the space 25a. Therefore, if the vehicle type can be identified, it is possible to determine whether the rear vehicle 21 can move within the space 25a according to the vehicle length of the rear vehicle 21 from the first set value for each vehicle type, and the accuracy of the determination can be easily improved. Note that similarly, the second set value serving as a criterion for the notification unit 7 not to give a notification may also vary according to the vehicle type.

[0047] Next, a method for ensuring the safety of the rear vehicle 21 using the safety ensuring device 1a of the rear vehicle 21 according to the second embodiment will be described. FIG. 10 is a flowchart showing details of the method for ensuring the safety of the rear vehicle 21 using the safety ensuring device 1a of the rear vehicle 21 according to the second embodiment. First, it is assumed that the host vehicle 13 is traveling on the road 11. In this case, the measurement unit 3 images the rear of the host vehicle 13 using the rear camera 3b. Further, the measurement unit 3 determines whether an object 17 or the like has been detected from the captured video by known image analysis or the like. If detected, the process proceeds to S22-1, and if not detected, this process is repeated (S21 in FIG. 10).

[0048] When it is determined in S21 that an object 17 or the like has been detected, the measurement unit 3 determines whether the object 17 or the like is at the front end 33 of the crosswalk 31. If it is at the front end 33, the process proceeds to S23. If it is not at the front end 33, the process proceeds to S22-2 (S22-1 in FIG. 10). When it is determined in S22-1 that the object 17 or the like is not at the front end 33, the measurement unit 3 determines whether the object 17 or the like is the barrier 41 of the level crossing 39. If it is determined that it is the barrier 41, the process proceeds to S23. If it is determined that it is not the barrier 41, the process proceeds to S22-3 (S22-2 in FIG. 10). When it is determined in S22-2 that the object 17 or the like is not the barrier 41, the measurement unit 3 determines whether the object 17 or the like is the traffic signal 45. If it is determined that it is the traffic signal 45, the process proceeds to S23. If it is determined that it is not the traffic signal 45, the process proceeds to S22-4 (S22-3 in FIG. 10). At this time, the presence or absence of the intersection 43 may also be determined. When it is determined in S22-3 that the object 17 or the like is not the traffic signal 45, the measurement unit 3 determines whether the object 17 or the like is the lane 49 of the road 11. Specifically, it is determined whether it is the lane 49 at the intersection 47 without the traffic signal 45 based on whether the lane 49 ends at the intersection 47. If it is determined that it is the lane 49, the process proceeds to S22-5. If it is determined that it is not the lane 49, the process returns to S21 (S22-4 in FIG. 10). At this time, the presence or absence of the intersection 47 may also be determined. When it is determined in S22-4 that the object 17 or the like is the lane 49 of the road 11, the measurement unit 3 determines whether the lane 51 of the road that intersects the road 11 at the intersection 47 has come within the detection range. As a result, if it is determined that it has come within the detection range, the process proceeds to S23. If it is determined that it is not within the detection range, this process is repeated (S22-5 in FIG. 10).

[0049] When the process shifts to S23, since the measurement unit 3 assumes (estimates) the location where the object 17 is installed, the measurement unit 3 acquires the traveling pulse signal PS and records the number of traveling pulses at the location where the object 17 is assumed to be installed (S23 in FIG. 10). Next, the measurement unit 3 determines whether the host vehicle 13 has stopped. If it determines that the vehicle has stopped, it proceeds to S25. If it determines that the vehicle has not stopped, it repeats this process (S24 in FIG. 10). When it is determined in S24 that the host vehicle 13 has stopped, the measurement unit 3 acquires the traveling pulse signal PS and records the number of traveling pulses at the time of stopping. Further, the measurement unit 3 subtracts the number of pulses acquired in S23 from the number of traveling pulses acquired when the host vehicle 13 stopped to obtain the difference in the number of pulses, and calculates the distance 25 from the obtained difference (S25 in FIG. 10, measurement step). Next, the determination unit 5 determines whether there is a rear vehicle 21 in the video of the rear of the host vehicle 13 captured by the rear camera 3b. If there is, it proceeds to S27. If not, the process ends and returns (S26). When it is determined in S26 that there is a rear vehicle 21, the determination unit 5 determines whether the rear vehicle 21 is a passenger car from the video of the rear of the host vehicle 13 captured by the rear camera 3b. If it is a passenger car, it proceeds to S28-1. If it is not a passenger car, it proceeds to S28-2 (S27 in FIG. 10).

[0050] When the determination unit 5 determines in S27 that the rear vehicle 21 is a passenger car, the determination unit 5 sets the first set value and the second set value to the values for passenger car setting and proceeds to S29-1 (S28-1 in FIG. 10). In S29-1, the determination unit 5 determines whether the distance 25 is greater than the first set value for passenger car setting (determination step). If it is determined that the distance 25 (difference in the number of pulses) is greater than the first set value for passenger car setting, it proceeds to S30-1. If it is determined that it is not greater than the first set value for passenger car setting, it proceeds to S33-1 (S29-1 in FIG. 10). When it is determined in S29-1 that the distance 25 is not greater than the first set value for passenger car setting, there is a possibility that the rear vehicle 21 may not fit within the space 25a. Therefore, the determination unit 5 instructs the notification unit 7 to issue a notification to hold the passing of the rear vehicle 21. The notified notification unit 7 issues a notification to hold the passing of the rear vehicle 21 (S33-1 in FIG. 10, notification step).

[0051] When it is determined in S29-1 that the distance 25 (the difference in the number of pulses) is greater than the first set value of the passenger car setting, the determination unit 5 determines whether the distance 25 is less than the second set value of the passenger car setting. If it is determined that the distance 25 is less than the second set value of the passenger car setting, the process proceeds to S31-1. If it is determined that the distance 25 is not less than the second set value of the passenger car setting, the process proceeds to S32-1 (S30-1 in FIG. 10). When it is determined in S30-1 that the distance 25 is less than the second set value of the passenger car setting, the determination unit 5 instructs the notification unit 7 to issue a notification prompting the following vehicle 21 to pass. The notified notification unit 7 issues a notification prompting the following vehicle 21 to pass (S31-1 in FIG. 10, notification process). When it is determined in S30-1 that the distance 25 is not less than the second set value of the passenger car setting, the determination unit 5 returns without instructing the notification unit 7 to issue a notification to the following vehicle 21 (S32-1 in FIG. 8).

[0052] On the other hand, when the determination unit 5 determines in S27 that the following vehicle 21 is not a passenger car, the determination unit 5 sets the first set value and the second set value to the values of the truck setting and proceeds to S29-2 (S28-2 in FIG. 10). In S29-2, the determination unit 5 determines whether the distance 25 is greater than the first set value of the truck setting (determination process). If it is determined that the distance 25 is greater than the first set value of the truck setting, the process proceeds to S30-2. If it is determined that the distance 25 is not greater than the first set value of the truck setting, the process proceeds to S33-2 (S29-2 in FIG. 10). If it is determined in S29-2 that the distance 25 is not greater than the first set value of the truck setting, there is a possibility that the following vehicle 21 may not fit within the space 25a. Therefore, the determination unit 5 instructs the notification unit 7 to issue a notification to hold the following vehicle 21 from passing. The notified notification unit 7 issues a notification to hold the following vehicle 21 from passing (S33-2 in FIG. 10, notification process).

[0053] When it is determined in S29-2 that the distance 25 is greater than the first set value of the track setting, the determination unit 5 determines whether the distance 25 is less than the second set value of the track setting. If it is determined that the distance 25 is less than the second set value of the track setting, the process proceeds to S31-2; if it is determined that the distance 25 is not less than the second set value of the track setting, the process proceeds to S32-2 (S30-2 in FIG. 10). When it is determined in S30-2 that the distance 25 is less than the second set value of the track setting, the determination unit 5 instructs the notification unit 7 to issue a notification prompting the following vehicle 21 to pass. The notified notification unit 7 issues a notification prompting the following vehicle 21 to pass (S31-2 in FIG. 10, notification step). When it is determined in S30-2 that the distance 25 is not less than the second set value, the determination unit 5 returns without instructing the notification unit 7 to issue a notification to the following vehicle 21 (S32-2 in FIG. 8). Note that the flowchart in FIG. 10 assumes that the following vehicle 21 is not detected on the travel path 11 between the host vehicle 13 and the object 17. Therefore, if the following vehicle 21 is detected on the travel path 11 between the host vehicle 13 and the object 17 during the execution of the flowchart in FIG. 10, the process is aborted and the routine returns. The above is the description of the method for ensuring the safety of the following vehicle 21 using the safety ensuring device 1a for the following vehicle 21 according to the second embodiment.

[0054] As described above, the safety ensuring device 1 for the following vehicle 21 according to the second embodiment notifies the following vehicle 21 whether it can move so as to fit within the space 25a between the host vehicle 13 and the dangerous area 15 when the host vehicle 13 stops after passing through the dangerous area 15. Therefore, the second embodiment has the same effect as the first embodiment.

[0055] Also, in the second embodiment, the measurement unit 3 measures the distance assuming that the point where the object 17 is displayed on the rear camera 3b installed on the host vehicle 13 and imaging the rear of the vehicle is the point where the object 17 is installed. With this configuration, since the rear camera 3b can also image the following vehicle 21, it is possible to determine the presence or absence and vehicle type of the following vehicle 21, and to make judgments and notifications according to the actual rear situation.

[0056] Also, in the second embodiment, the determination unit 5 detects the presence or absence of the rear vehicle 21 from the video of the rear camera 3b. Further, when the rear vehicle 21 is detected, the determination unit 5 identifies the vehicle type and determines whether the rear vehicle 21 can move so as to fit within the space 25a between the danger area 15 and the host vehicle 13 based on the identified vehicle type. Therefore, it is possible to specifically determine whether the rear vehicle 21 can move so as to fit within the space 25a according to the vehicle length of the rear vehicle 21, and thus the accuracy of the determination can be improved.

[0057] Also, in the second embodiment, the determination unit 5 determines that the rear vehicle 21 can move so as to fit within the space 25a when the distance 25 measured by the measurement unit 3 is longer than a preset value (first preset value) for each vehicle type. Therefore, if the vehicle type can be identified, it is possible to determine whether the rear vehicle 21 can move within the space 25a according to the vehicle length of the rear vehicle 21 from the set value for each vehicle type, and thus the accuracy of the determination can be easily improved.

[0058] As described above, the present invention has been described based on the embodiments. However, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the present invention, or other technologies may be appropriately combined within the possible range. Further, known or well-known technologies may be combined within the possible range.

[0059] For example, in the above-described embodiment, as the rear vehicle 21 that issues the notification, a vehicle traveling on the same travel route 11 as the host vehicle 13 has been exemplified. However, a vehicle that is about to turn right or left from a road intersecting the travel route 11 and travel within the travel route 11 may also be notified.

Explanation of Reference Numerals

[0060] 1, 1a: Rear vehicle safety assurance device 3: Measurement unit (measurement means) 3a: Front camera 3b: Rear camera 5: Determination unit (determination means) 7: Notification unit (notification means) 11: Travel route 13: Host vehicle 15: Danger area 17: Object 21: Rear vehicle 25: Distance 25a: Space 31: Crosswalk 33: Front end 39: Level crossing 41: Barrier 43: Intersection 45: Traffic signal 47: Intersection 51: Lane 53: Intersection A: Travel direction PS: Travel pulse signal

Claims

1. When a vehicle stops on a road, in the case where there is an object indicating a danger area that is predetermined to be dangerous if a following vehicle stops behind the vehicle, measuring means for measuring the distance between the object and the rear end of the vehicle, and based on the distance measured by the measuring means, determination means for determining whether the following vehicle can move so as to fit within the space between the danger area and the vehicle, a safety assurance device for a following vehicle mounted on the vehicle, further comprising notification means for notifying the following vehicle whether it can move so as to fit within the space based on the determination of the determination means A safety assurance device for a following vehicle, characterized by the above.

2. The measuring means, measures the distance from the difference between the number of travel pulses generated by the vehicle speed sensor when the vehicle passes the object and the number of travel pulses generated by the vehicle speed sensor when the vehicle stops after passing the object. The safety assurance device for a following vehicle according to claim 1, characterized by the above.

3. The measuring means, detects the object with a front camera installed on the vehicle and imaging the front of the vehicle before the vehicle passes the object, and measures the distance by assuming the point where the object disappears from the imaging range of the front camera as the point where the object is installed. The safety assurance device for a following vehicle according to claim 1, characterized by the above.

4. The measuring means, measures the distance by assuming the point where the object is displayed on a rear camera installed on the vehicle and imaging the rear of the vehicle as the point where the object is installed. The safety assurance device for a following vehicle according to claim 1, characterized by the above.

5. The determination means detects the presence or absence of the following vehicle from the video of the rear camera, identifies the vehicle type when the following vehicle is detected, and determines whether the following vehicle can move so as to fit within the space between the danger area and the vehicle based on the identified vehicle type. The safety assurance device for a following vehicle according to claim 4, characterized by the above.

6. The determination means determines that the following vehicle can move so as to fit within the space when the distance measured by the measuring means is longer than a set value predetermined for each vehicle type. The safety assurance device for a following vehicle according to claim 5, characterized by the above.

7. The danger area is a crosswalk, The object is the front end of the crosswalk in the traveling direction of the host vehicle. The safety ensuring device for a following vehicle according to claim 1, characterized in that.

8. The dangerous area is a railroad crossing, The object is a blocking device provided at the front end of the railroad crossing in the traveling direction of the host vehicle. The safety ensuring device for a following vehicle according to claim 1, characterized in that.

9. The dangerous area is an intersection where a traffic signal is installed, The object is the traffic signal. The safety ensuring device for a following vehicle according to claim 1, characterized in that.

10. The dangerous area is an intersection where no traffic signal is installed, The object is the lane at the front end in the traveling direction of the host vehicle among the lanes intersecting the traveling road at the intersection. The safety ensuring device for a following vehicle according to claim 1, characterized in that.

11. The dangerous area is an intersection where a crosswalk and a traffic signal are installed, The object is the front end of the crosswalk and the traffic signal in the traveling direction of the host vehicle, When the measuring means detects both the front end of the crosswalk and the traffic signal, The front end of the crosswalk is preferentially set as the object. The safety ensuring device for a following vehicle according to claim 1, characterized in that.

12. The notification means, When the determination means determines that the following vehicle can move so as to fit within the space, a notification prompting passage through the dangerous area is given to the following vehicle, and when it is determined that the following vehicle may not be able to move so as to fit within the space, a notification stopping passage through the dangerous area is given to the following vehicle. The safety ensuring device for a following vehicle according to any one of claims 1 to 11, characterized in that.

13. The notification means, Even when the determination means determines that the following vehicle can move so as to fit within the space, only when the distance measured by the measuring means is less than a predetermined distance, the following vehicle is notified whether it can move so as to fit within the space. The safety ensuring device for a following vehicle according to any one of claims 1 to 11, characterized in that.

14. When the bicycle stops on the road, if there is an object indicating a danger area that is predetermined to be dangerous when a following vehicle stops behind the bicycle, a measuring step of measuring the distance between the object and the rear end of the bicycle, and a judging step of judging whether the following vehicle can move so as to fit within the space between the danger area and the bicycle based on the distance measured in the measuring step. A method for ensuring the safety of a following vehicle, comprising: Based on the judgment in the judgment step, further comprising a notification step of notifying the following vehicle whether it can move so as to fit within the space. A method for ensuring the safety of a following vehicle, characterized by the above.

Images