Speed limit reporting method and speed limit reporting device

Abstract

This speed limit reporting device (3) comprises a control unit (21) that reports the speed limit of a road on which a vehicle travels. The control unit (21) acquires an image captured by a front camera (15) mounted on a vehicle, detects a speed limit of a road on which the vehicle travels from the acquired image, reports the detected speed limit to the interior of a vehicle cabin of the vehicle, and, when the vehicle enters a roundabout intersection, suppresses a change in the speed limit reported before the vehicle enters the roundabout intersection.

Description

Speed Limit Notification Method and Speed Limit Notification Device

[0008] ,

[0001] The present invention relates to a speed limit notification method and a speed limit notification device.

[0002] Conventionally, a driving support method for displaying the speed limit read from map information on a display device is disclosed in Patent Document 1. In the driving support method disclosed in Patent Document 1, in a section where a temporary speed limit such as a construction site is set, even if the speed limit registered in the map information changes, the update of the speed limit displayed on the display device is prohibited.

[0003] Japanese Unexamined Patent Application Publication No. 2023-123036

[0004] However, in the above-described conventional driving support method, when the self-position on the map deviates from the actual position of the vehicle, a speed limit different from the speed limit that should be displayed at the actual position of the vehicle is displayed. In particular, in a roundabout, many connecting roads with different speed limits are connected to the circular road. Therefore, when the vehicle passes near a connecting road while traveling inside the roundabout, the displayed speed limit changes each time, and thus there is a problem that the driver feels annoyed due to the frequent change of the speed limit.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a speed limit notification method and an apparatus thereof that can prevent the driver from feeling annoyed due to the frequent change of the speed limit when traveling inside a roundabout.

[0006] In the speed limit notification method and the apparatus thereof according to one aspect of the present invention, when the vehicle enters a roundabout, the change of the speed limit notified before the vehicle enters the roundabout is suppressed.

[0007] According to the present invention, it is possible to prevent the driver from feeling annoyed due to the frequent change of the speed limit when traveling inside a roundabout.

[0008] Figure 1 is a block diagram showing the configuration of a speed limit notification system equipped with a speed limit notification device. Figure 2 is a diagram showing an example of a speed limit displayed by the speed limit notification device. Figure 3 is a flowchart showing the processing procedure for speed limit notification processing by the speed limit notification device. Figure 4 is a diagram showing an example of a speed limit displayed in a roundabout by the speed limit notification device. Figure 5 is a diagram showing an example of a conventionally displayed speed limit in a roundabout. Figure 6 is a diagram showing an example of a speed limit displayed in a roundabout by the speed limit notification device. Figure 7 is a diagram showing an example of a speed limit displayed in a roundabout by the speed limit notification device.

[0009] The speed limit notification method and speed limit notification device according to this embodiment will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted.

[0010] Referring to Figure 1, the configuration of the speed limit notification system equipped with the speed limit notification device according to this embodiment will be described. The speed limit notification system 1 is a system mounted on a vehicle that notifies the speed limit of the road on which the vehicle is traveling. As shown in Figure 1, the speed limit notification system 1 includes a camera ECU (electronic control unit) 5 and a map ECU 7. The speed limit notification system 1 also includes a vehicle sensor 11 mounted on the vehicle, a GNSS (Global Navigation Satellite System) receiver 13, a front camera 15, a display device 17, and a speaker 19.

[0011] The camera ECU 5 is equipped with a speed limit notification device 3 that notifies the vehicle of the speed limit of the road on which the vehicle is traveling. Specifically, the speed limit notification device 3 detects road signs from the image in front of the vehicle captured by the front camera 15, detects the speed limit displayed on the detected road sign, and notifies the detected speed limit from either or both of the display device 17 and the speaker 19.

[0012] The speed limit notification device 3 acquires the vehicle's own position and map data from the map ECU 7. When the vehicle enters an intersection or similar location, and the road type included in the map data becomes a specific type of road such as an intersection, the speed limit notification device 3 switches from detecting the speed limit with the front camera 15 to notifying the speed limit recorded in the map data.

[0013] The speed limit notification device 3 comprises a control unit 21 and a storage unit 23. The control unit 21 is a controller that performs the process of notifying the speed limit of the road on which the vehicle is traveling. Specifically, the control unit 21 acquires images captured by the front camera 15 mounted on the vehicle, detects the speed limit of the road on which the vehicle is traveling from the acquired images, and notifies the detected speed limit inside the vehicle's cabin. Furthermore, when the vehicle enters a roundabout, the control unit 21 suppresses the change in the speed limit that was notified before the vehicle entered the roundabout.

[0014] The memory unit 23 is a memory or database that stores information necessary to perform the process of notifying the vehicle of the speed limit of the road it is traveling on. Specifically, the memory unit 23 stores images acquired from the camera ECU 5 and map data acquired from the map ECU 7, and records setting values ​​such as the first distance and second distance used when the vehicle exits a roundabout.

[0015] The speed limit notification device 3 is a computer composed of general-purpose electronic circuits including a microcomputer, microprocessor, and CPU, as well as peripheral devices such as memory, and has a computer program installed to perform the process of notifying the speed limit. Each function of the speed limit notification device 3 can be implemented by one or more processing circuits.

[0016] The camera ECU 5 controls the front camera 15 to capture an image of the area in front of the vehicle and outputs the captured image to the speed limit notification device 3. The front camera 15 is an imaging means mounted on the vehicle that captures an image of the area in front of the vehicle.

[0017] The map ECU 7 performs a process to estimate the vehicle's own position based on the vehicle's current position obtained from the GNSS receiver 13 and the map data recorded in the map database 25. The map data records links and nodes as elements representing the road network, and each link is assigned a road type. The road type records the attributes of roads such as expressways, toll roads, national roads, and prefectural roads, and among them is the road type "roundabout" which indicates that the road is within a roundabout.

[0018] Map database 25 stores map information. The map information is high-precision 3D map data such as HD maps, and includes not only location information on the map of three-dimensional objects such as traffic lights and utility poles installed on roads and sidewalks, or lane boundary lines, but also information such as road speed limits, road regulations, and road types.

[0019] The vehicle sensor 11 is a sensor mounted on the vehicle and includes, for example, a vehicle speed sensor, yaw rate sensor, steering sensor, gyro sensor, accelerator sensor, and brake sensor. In addition, the ON / OFF signals of the turn signals are also included in the signals output from the vehicle sensor 11. This information is output as vehicle information to the camera ECU 5 and the map ECU 7.

[0020] The display device 17 is a device that displays the speed limit output from the speed limit notification device 3. For example, as shown in Figure 2, a speed limit display unit 33 is provided adjacent to the speed display unit 31 in the speed meter, and the speed limit is displayed on this speed limit display unit 33. Alternatively, the speed limit may be displayed on a head-up display.

[0021] The speaker 19 is installed in the car audio system that outputs sound into the vehicle's cabin, and outputs the speed limit announcement sound output from the speed limit notification device 3 into the vehicle's cabin.

[0022] Next, the speed limit notification process by the speed limit notification device 3 according to this embodiment will be described. Figure 3 is a flowchart showing the processing procedure for the speed limit notification process. The speed limit notification process shown in Figure 3 starts when the vehicle's power is turned ON.

[0023] As shown in Figure 3, in step S101, the control unit 21 acquires an image of the front of the vehicle captured by the front camera 15.

[0024] In step S103, the control unit 21 detects the speed limit of the road on which the vehicle is traveling from the image acquired in step S101. Specifically, the control unit 21 detects road signs from the image in front of the vehicle and detects the speed limit displayed on the detected road signs.

[0025] In step S105, the control unit 21 notifies the vehicle's passenger compartment of the speed limit detected in step S103. Specifically, the control unit 21 displays the speed limit on the display device 17 and outputs the speed limit as an audible message from the speaker 19. For example, as shown in Figure 2, the speed limit is displayed on the speed limit display unit 33 located in the speedometer, and when the speed limit changes, the change in the speed limit is announced by voice.

[0026] In step S107, the control unit 21 determines whether the vehicle has entered a roundabout. Specifically, the control unit 21 obtains map data of the vehicle's current location from the map ECU 7, and if it detects that the road type of the link included in the obtained map data is "roundabout", it determines that the vehicle has entered a roundabout. If it is determined that the vehicle has entered a roundabout, the process proceeds to step S109; if it is determined that the vehicle has not entered a roundabout, the process proceeds to step S125.

[0027] In step S109, the control unit 21 suppresses the change to the speed limit that was announced before the vehicle entered the roundabout, because the vehicle has entered the roundabout. As a result, once the vehicle enters the roundabout, the speed limit that was announced before entering the roundabout remains unchanged.

[0028] For example, as shown in Figure 4, when a vehicle is traveling on connecting road R1, the front camera 15 detects the speed limit of connecting road R1, which is 60 km / h, and the control unit 21 notifies the vehicle of the speed limit of 60 km / h. Furthermore, even when the vehicle enters the roundabout RA, the change in the speed limit is suppressed, so the control unit 21 maintains the speed limit of connecting road R1 as it was before entering the roundabout RA, and continues to notify the vehicle of the speed limit of connecting road R1, which is 60 km / h, while it is traveling within the roundabout RA.

[0029] Incidentally, when a vehicle enters a roundabout and the road type of the link becomes "roundabout," the control unit 21 can switch from detecting the speed limit with the front camera 15 to notifying the speed limit recorded in the map data. In this case, as shown in Figure 5, when the vehicle enters roundabout RA and reaches the position of arrow 51, the road type of the link corresponding to arrow 51 changes to "roundabout." At this point, the control unit 21 switches to notifying the speed limit of 50 km / h recorded in the map data.

[0030] However, when a vehicle is traveling through the roundabout RA and approaches connecting road R2, if its position on the map differs from the actual vehicle position, the control unit 21 mistakenly announces the speed limit of connecting road R2, which is 70 km / h. After passing connecting road R2, the control unit 21 announces the speed limit of roundabout RA, which is 50 km / h, but then changes the speed limit back to 70 km / h before connecting roads R3 and R4. As a result, the speed limit changes frequently in the roundabout, which drivers find annoying.

[0031] In contrast, as shown in Figure 4, if the speed limit remains the same as before the vehicle entered the roundabout RA, the speed limit will not change frequently within the roundabout RA, thus eliminating any inconvenience for the driver.

[0032] In step S111, the control unit 21 determines whether a speed limit has been detected from the image captured by the front camera 15 while the vehicle is traveling through a roundabout. If a speed limit has been detected, the process proceeds to step S113; otherwise, the process proceeds to step S115.

[0033] In step S113, the control unit 21 detects the speed limit from the image captured by the front camera 15 while the vehicle is traveling through a roundabout, and therefore notifies the vehicle's interior of the speed limit detected from the image captured by the front camera 15. In other words, when the vehicle is traveling through a roundabout and the front camera 15 can detect the speed limit, the control unit 21 immediately notifies the detected speed limit.

[0034] For example, as shown in Figure 6, if a sign 61 is installed within the roundabout RA, and the front camera 15 captures an image of the sign 61 and detects a speed limit of 50 km / h, the control unit 21 immediately switches the speed limit to 50 km / h and notifies the driver. Thereafter, the 50 km / h speed limit is notified until the driver exits the roundabout RA.

[0035] In step S115, the control unit 21 determines whether the vehicle has exited the roundabout. Specifically, the control unit 21 obtains map data of the vehicle's current location from the map ECU 7, and if it detects that the road type of the link included in the obtained map data is other than "roundabout", it determines that the vehicle has exited the roundabout. If it is determined that the vehicle has exited the roundabout, the process proceeds to step S117; if it is determined that the vehicle has not exited the roundabout, the process returns to step S111.

[0036] In step S117, the control unit 21 determines whether or not the speed limit was detected from the image captured by the front camera 15 after the vehicle exits the roundabout. If the speed limit was not detected, the process proceeds to step S119; if the speed limit was detected, the process proceeds to step S121.

[0037] In step S119, the control unit 21 determines whether the vehicle has traveled a predetermined first distance from the roundabout. If the vehicle has traveled the first distance, the process proceeds to step S125; otherwise, the process returns to step S117.

[0038] The control unit 21 maintains the speed limit that was announced within the roundabout even after the vehicle has exited the roundabout. Then, when the vehicle has traveled a first distance, the control unit 21 determines that the vehicle has definitely exited the roundabout and switches from processing within the roundabout to normal processing. In other words, when a vehicle exits a roundabout, the control unit 21 maintains the speed limit that was announced within the roundabout until the vehicle has traveled a first distance from the roundabout.

[0039] For example, as shown in Figure 4, when the vehicle moves to the position of arrow 41, the road type of the link corresponding to arrow 41 becomes something other than "roundabout," so the control unit 21 determines that the vehicle has exited roundabout RA. The control unit 21 then maintains the speed limit of 60 km / h, which was announced within roundabout RA, until the vehicle has traveled a first distance L1, for example, 20 m, from roundabout RA. After this, when the vehicle has traveled the first distance L1, the system switches to the normal process of detecting the speed limit with the front camera 15, so the control unit 21 detects and announces the speed limit of 70 km / h, which is the speed limit of connecting road R6.

[0040] The first distance is the distance required to confirm that the vehicle has exited the roundabout, and is determined through experimentation or simulation. In particular, the first distance is set to be greater than the error between the vehicle's position on the map and its actual position. Alternatively, instead of the first distance, the time required to travel the first distance may be set as the first hour, and the system may determine whether or not the first hour has elapsed.

[0041] In step S121, the control unit 21 determines whether the vehicle has traveled a predetermined second distance from the circular intersection. If the vehicle has not traveled the second distance, the control unit 21 continues to determine whether the vehicle has traveled the second distance. If the vehicle has traveled the second distance, the process proceeds to step S123. Note that the second distance may be set to a distance shorter than the first distance. Instead of the second distance, the time required to travel the second distance may be set as the second time, and it may be determined whether the second time has elapsed.

[0042] In step S123, the control unit 21 notifies the speed limit detected in step S117 inside the vehicle cabin of the vehicle. That is, when the vehicle exits the circular intersection and the speed limit is detected from the image captured by the front camera 15, the control unit 21 maintains the speed limit notified inside the circular intersection until the vehicle travels the second distance from the circular intersection.

[0043] For example, as shown in FIG. 7, there may be a case where a sign 71 is installed immediately after the vehicle moves to the position of the arrow 41 and exits the circular intersection RA. In this case, even if the control unit 21 detects the speed limit from the image of the sign 71, the control unit 21 maintains the speed limit of 60 km / h notified inside the circular intersection RA until the vehicle travels the second distance L2. After that, when the vehicle travels to the second distance L2, the control unit 21 switches to and notifies the speed limit of 70 km / h, which is the speed limit of the connecting road R6 detected by the sign 71. Thereby, when the speed limit can be detected from the sign immediately after exiting the circular intersection, the speed limit can be notified earlier before traveling the first distance.

[0044] In step S125, the control unit 21 determines whether the power supply of the vehicle has been turned off. If the power supply has not been turned off, the process returns to step S101 and switches to the normal process of detecting the speed limit with the front camera 15. On the other hand, if the power supply has been turned off, the speed limit notification process according to this embodiment ends.

[0045] As described in detail above, the speed limit notification device 3 according to this embodiment acquires an image captured by the front camera 15 mounted on the vehicle, detects the speed limit of the road on which the vehicle is traveling from the acquired image, and notifies the detected speed limit to the interior of the vehicle cabin. Then, when the vehicle enters the roundabout, the speed limit notification device 3 suppresses the change of the speed limit that was notified before the vehicle entered the roundabout. Thereby, within the roundabout, the change of the notified speed limit is suppressed, so it is possible to prevent the speed limit from frequently changing when driving within the roundabout and causing annoyance to the driver.

[0046] Furthermore, when the vehicle is traveling within the roundabout and the speed limit is detected from the image captured by the front camera 15, the speed limit notification device 3 according to this embodiment notifies the speed limit detected from the image captured by the front camera 15 to the interior of the vehicle cabin. Thereby, when the speed limit is detected by the front camera 15 within the roundabout, it is possible to notify a more accurate speed limit detected by the front camera 15.

[0047] Also, when the vehicle exits the roundabout, the speed limit notification device 3 according to this embodiment maintains the speed limit that was notified before the vehicle exited the roundabout until the vehicle travels a predetermined first distance from the roundabout. Thereby, it is possible to prevent the speed limit from being changed by mistakenly recognizing that the vehicle has exited the roundabout, so it is possible to prevent the speed limit from frequently changing when driving within the roundabout and causing annoyance to the driver.

[0048] Furthermore, when the vehicle exits the roundabout and the speed limit is detected from the image captured by the front camera 15, the speed limit notification device 3 according to this embodiment maintains the speed limit notified within the roundabout until the vehicle travels a second distance shorter than the first distance from the roundabout. Thereby, when the speed limit can be detected by the front camera 15 immediately after the vehicle exits the roundabout, it is possible to quickly notify the accurate speed limit detected by the front camera 15.

[0049] Furthermore, in this embodiment, the speed limit notification device 3 may prohibit the change of the speed limit that was announced before the vehicle entered the roundabout when the vehicle enters the roundabout. As a result, changes to the announced speed limit are prohibited within the roundabout, preventing drivers from feeling annoyed by frequent changes in the speed limit while driving within the roundabout.

[0050] As described above, embodiments of the present invention have been presented, but the statements and drawings that constitute part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art from this disclosure.

[0051] 1 Speed ​​limit notification system 3 Speed ​​limit notification device 5 Camera ECU 7 Map ECU 11 Vehicle sensor 13 GNSS receiver 15 Front camera 17 Display device 19 Speaker 21 Control unit 23 Memory unit 25 Map database 31 Speed ​​display unit 33 Speed ​​limit display unit 41, 51 Arrows 61, 71 Signs R1-R6 Connecting roads RA Roundabout L1 First distance L2 Second distance

Claims

1. A speed limit notification method using a controller that notifies the speed limit of the road on which a vehicle is traveling, comprising: acquiring an image captured by a camera mounted on the vehicle; detecting the speed limit of the road on which the vehicle is traveling from the acquired image; notifying the detected speed limit inside the vehicle's cabin; and, when the vehicle enters a roundabout, suppressing any changes to the speed limit that was notified before the vehicle entered the roundabout.

2. The speed limit notification method according to claim 1, wherein if the vehicle enters the roundabout, the change of the speed limit that was notified before the vehicle entered the roundabout is prohibited.

3. The speed limit notification method according to claim 1, wherein when the vehicle is traveling within the roundabout, if a speed limit is detected from an image captured by the camera, the speed limit detected from the image captured by the camera is notified inside the vehicle's cabin.

4. The speed limit notification method according to any one of claims 1 to 3, wherein when the vehicle exits the roundabout, the speed limit that was notified before the vehicle exited the roundabout is maintained until the vehicle travels a predetermined first distance from the roundabout.

5. The speed limit notification method according to claim 4, wherein, when the vehicle exits the roundabout and the speed limit is detected from the image captured by the camera, the speed limit that was announced within the roundabout is maintained until the vehicle travels a second distance shorter than the first distance from the roundabout.

6. A speed limit notification device comprising: a controller for notifying the speed limit of the road on which a vehicle is traveling; the controller acquires an image captured by a camera mounted on the vehicle; detects the speed limit of the road on which the vehicle is traveling from the acquired image; notifies the detected speed limit inside the vehicle's cabin; and, when the vehicle enters a roundabout, suppresses any changes to the speed limit that was notified before the vehicle entered the roundabout.

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