Road type determination device

Abstract

To provide a road type determining device capable of appropriately determining whether a road on which a vehicle travels is a motorway.SOLUTION: A road type determining device for determining whether a road on which a vehicle travels is a motorway, comprises: a road sign recognition unit that recognizes a road sign in front of a vehicle based on an image captured by a front camera of the vehicle; a distance detection unit that detects a distance from the vehicle to the road sign based on the captured image or a detection result of a radar sensor of the vehicle when the road sign is recognized by the road sign recognition unit; a character size determination unit that determines whether a character size of the road sign is equal to or larger than a size of the motorway, based on the captured image and the distance from the vehicle to the road sign; and a road type determination unit that determines that the road on which the vehicle is traveling is the motorway when the character size determination unit determines that the character size of the road sign is equal to or larger than the size of the motorway.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a road type determination device.

Background Art

[0002] Conventionally, as a technical document related to a road type determination device, Japanese Unexamined Patent Application Publication No. 2020-173730 is known. This publication shows a device that determines the road type of the road on which a vehicle is traveling by recognizing road signs from an image captured by a camera of the vehicle in front of the vehicle.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when determining the road type from road signs, a method of distinguishing an expressway from a general road by the color of the road signs is known. However, there are cases where it is difficult to identify the color of the road signs due to the influence of the color filter of the vehicle's camera, etc., or there are countries or regions where the color of the road signs is not distinguished between expressways and general roads. Even in such cases, there is a need for means to appropriately determine the road type (whether it is an expressway or not) from road signs.

Means for Solving the Problems

[0005] One aspect of the present invention is a road type determination device that determines whether the driving road of a vehicle is an exclusive motor vehicle road. The device includes a road sign recognition unit that recognizes road signs in front of the vehicle based on an imaging image of a front camera of the vehicle, a distance detection unit that detects the distance from the vehicle to the road sign when a road sign is recognized by the road sign recognition unit, based on the imaging image or the detection result of a radar sensor of the vehicle, a character size determination unit that determines whether the character size of the road sign is equal to or greater than the exclusive motor vehicle road size based on the imaging image and the distance from the vehicle to the road sign, and a road type determination unit that determines that the driving road of the vehicle is an exclusive motor vehicle road when the character size determination unit determines that the character size of the road sign is equal to or greater than the exclusive motor vehicle road size. The road type determination unit estimates whether the driving road is an exclusive motor vehicle road based on map information including the vehicle's own position and the position information of the exclusive motor vehicle road. When it is estimated that the driving road is an exclusive motor vehicle road and the character size determination unit does not determine that the character size of the road sign is equal to or greater than the exclusive motor vehicle road size, the driver of the vehicle is asked whether the driving road is an exclusive motor vehicle road. When the driver answers that the driving road is an exclusive motor vehicle road, Permit driving assistance or autonomous driving on exclusive roads for automobiles 。

[0006] According to the road type determination device according to one aspect of the present invention, it is determined whether the character size of the road sign is equal to or greater than the exclusive motor vehicle road size, and when it is determined that the character size of the road sign is equal to or greater than the exclusive motor vehicle road size, it is determined that the driving road of the vehicle is an exclusive motor vehicle road. Therefore, even when it is difficult to identify the color of the road sign due to the influence of the color filter of the front camera, it is possible to appropriately determine that the road is an exclusive motor vehicle road.

[0007] In the road type determination device according to one aspect of the present invention, a distance determination unit that determines whether the distance from the vehicle to the road sign is less than a determination threshold value is further provided. The character size determination unit may start determining the character size of the road sign when the distance determination unit determines that the distance is less than the determination threshold value. According to this road type determination device, when the distance determination unit determines that the distance is less than the determination threshold, the determination of the character size of the road sign is started. Therefore, it is possible to avoid unreasonably determining the character size from the captured image at the timing when the distance between the vehicle and the road sign is far, and it is possible to suppress the misjudgment of the character size.

Effect of the Invention

[0008] According to one aspect of the present invention, it is possible to appropriately determine that the driving road of the vehicle is an exclusive motor vehicle road.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] The road type determination device 1 shown in FIG. 1 is mounted on a vehicle such as a passenger car, and determines the road type of the driving road on which the vehicle travels. In the road type determination device 1 according to the present embodiment, it is determined whether or not the road type is an exclusive motor vehicle road. An exclusive motor vehicle road is a road designated based on laws and regulations for use only by motor vehicles for traffic.

[0012] [Configuration of Road Type Determination Device] Next, the configuration of the road type determination device according to the present embodiment will be described with reference to the drawings. As shown in FIG. 1, the road type determination device 1 includes an ECU [Electronic Control Unit] 10 that comprehensively manages the device. The ECU 10 is an electronic control unit having a CPU [Central Processing Unit] and a storage unit such as a ROM [Read Only Memory] or a RAM [Random Access Memory]. In the ECU 10, for example, various functions are realized by the CPU executing a program stored in the storage unit. The ECU 10 may be composed of a plurality of electronic units. The ECU 10 may be provided inside the camera.

[0013] The ECU 10 is connected to the front camera 2 and the radar sensor 3. The front camera 2 is an imaging device that images the situation in front of the vehicle. The front camera 2 is provided, for example, on the back side of the windshield of the vehicle and images the front of the vehicle. The front camera 2 may be provided at the front end of the vehicle such as a bumper. The front camera 2 transmits the captured image in front of the vehicle to the ECU 10. The front camera 2 may be a monocular camera or a stereo camera.

[0014] The radar sensor is a detection device that detects an object around the vehicle using radio waves (e.g., millimeter waves) or light. The radar sensor includes, for example, a millimeter wave radar or a lidar [LIDAR: Light Detection and Ranging]. The radar sensor transmits radio waves or light around the vehicle and detects the object by receiving the radio waves or light reflected by the object. The radar sensor transmits information on the detected object (information such as the size of the object and the distance to the object) to the ECU 10. The object includes road signs. The road signs include guiding signs or speed signs provided for the road.

[0015] Next, the functional configuration of the ECU 10 will be described. As shown in FIG. 1, the ECU 10 has a road sign recognition unit 11, a distance detection unit 12, a distance determination unit 13, a character size determination unit 14, and a road type determination unit 15.

[0016] The road sign recognition unit 11 recognizes the road signs in front of the vehicle based on the captured image of the front camera 2 of the vehicle. The road sign recognition unit 11 performs image processing such as edge processing and pattern matching on the captured image to recognize the road signs in the captured image. The road sign recognition unit 11 may recognize the road signs by deep learning using a neural network. The road sign recognition unit 11 may specify the direction in which the road sign exists with respect to the vehicle as the recognition result of the road signs in the captured image.

[0017] When the road sign recognition unit 11 recognizes a road sign, the distance detection unit 12 detects the distance from the vehicle to the road sign based on the captured image of the front camera 2 or the detection result of the radar sensor 3 of the vehicle. The distance estimation technique using the front camera 2 is known as SfM [Structure from Motion], for example. When the captured image of the front camera 2 contains distance information or the distance information can be estimated from the temporal change of the captured image, the distance detection unit 12 may detect the distance from the vehicle to the road sign based on the captured image. The distance detection unit 12 may directly detect the distance from the vehicle to the road sign based on the detection result of the radar sensor 3.

[0018] The distance determination unit 13 determines whether the distance from the vehicle to the road sign detected by the distance detection unit 12 is less than the determination threshold value. The determination threshold value is a preset threshold value. The determination threshold value may be 100 m, 50 m, 30 m, or 20 m. The determination threshold value may be set according to the imaging accuracy of the front camera 2. The value of the determination threshold value is not particularly limited.

[0019] The character size determination unit 14 determines the character size of road signs (such as guidance signs and speed signs). The character size determination unit 14 may start determining the character size of the road sign only when it is determined by the distance determination unit 13 that the distance from the vehicle to the road sign is less than the determination threshold. The character size determination unit 14 determines whether the character size of the road sign is equal to or greater than the exclusive lane size based on the captured image of the front camera 2 and the distance from the vehicle to the road sign detected by the distance detection unit 12. The exclusive lane size is used as a threshold related to the character size in the determination of the road type of an expressway. The exclusive lane size is appropriately set based on the laws and regulations of each country.

[0020] Here, Fig. 2(a) is a diagram for explaining the character size of a road sign on an expressway. Fig. 2(a) shows a guidance sign Ga on an expressway, a Chinese character notation Ca and an alphabetic notation Cb shown on the guidance sign Ga. Also shown are the width Wa and height Ta of the Chinese character notation Ca. Fig. 2(b) is a diagram for explaining the character size of a road sign on a general road. Fig. 2(b) shows a guidance sign Gb on a general road, a Chinese character notation Cd and an alphabetic notation Ce shown on the guidance sign Gb. Also shown are the width Wd and height Td of the Chinese character notation Cd.

[0021] As shown in Fig. 2(a) and Fig. 2(b), the size of the characters described on the road signs of expressways is set to be larger than that of the road signs of general roads by laws and regulations. For example, in Japan, there are places where the character size of the road signs on expressways is twice that of the road signs on general roads, and there are also places where it is four times.

[0022] The character size determination unit 14 recognizes the type of characters of the road signs from the captured image. For example, in Japan, since different regulations on character sizes apply to Chinese characters and alphabets, the character size determination unit 14 recognizes Chinese characters or alphabets as the type of characters. The character size determination unit 14 does not need to recognize the meaning of each character, and it is sufficient to recognize only the type of characters. The recognition of the character type can be performed by well-known image processing such as deep learning and pattern matching. The character size determination unit 14 does not need to recognize the type of characters for all the characters within the road sign, and it is sufficient to recognize the type of characters for at least one character.

[0023] Note that the character size determination unit 14 does not need to recognize the type of characters in a country or region where the type of characters shown on the road sign is basically one type, or in a country or region where there is no regulation such that the character size differs depending on the type of characters.

[0024] The character size determination unit 14 determines the character size using, for example, the width of the characters. In this case, the exclusive lane size can be set to a value corresponding to the width of the characters of the road signs on expressways specified by laws and regulations. The character size determination unit 14 determines that the width Wa of the characters of the Chinese character notation Ca shown in Fig. 2(a) is equal to or greater than the exclusive lane size. The character size determination unit 14 determines that the width Wd of the characters of the Chinese character notation Cd shown in Fig. 2(b) is less than the exclusive lane size.

[0025] The character size determination unit 14 may also determine the character size using the height of the characters. In this case, the exclusive lane size can be set to a value corresponding to the height of the characters of the road signs on expressways specified by laws and regulations. The character size determination unit 14 determines that the height Ta of the characters of the Chinese character notation Ca shown in Fig. 2(a) is equal to or greater than the exclusive lane size. The character size determination unit 14 determines that the height Td of the characters of the Chinese character notation Cd shown in Fig. 2(b) is less than the exclusive lane size.

[0026] The character size determination unit 14 may determine the character size using a calculation value obtained by calculating the width and height of the character with a predetermined arithmetic expression. In this case, the exclusive road size can be a value corresponding to the width and height of the characters of the road signs on the motor vehicle exclusive road specified by laws and regulations or the like.

[0027] The character size determination unit 14 determines the character size, for example, using as the calculation value half of the total value of the width and height of the character. For the Chinese character notation Ca shown in Fig. 2(a), the character size determination unit 14 determines that half of the total value of the width Wa and height Ta of the character is equal to or greater than the exclusive road size. For the Chinese character notation Cd shown in Fig. 2(b), the character size determination unit 14 determines that half of the total value of the width Wd and height Td of the character is less than the exclusive road size. Various arithmetic expressions can be adopted specifically for obtaining the calculation value. Note that the character size determination unit 14 may use the alphabet notation Cb or the alphabet notation Ce instead of the Chinese character notation for the determination of the character size.

[0028] The road type determination unit 15 determines whether the driving road on which the vehicle is traveling is a motor vehicle exclusive road. When the character size determination unit 14 determines that the character size of the road sign is equal to or greater than the exclusive road size, the road type determination unit 15 determines that the driving road of the vehicle is a motor vehicle exclusive road. When the character size determination unit 14 does not determine that the character size of the road sign is equal to or greater than the exclusive road size, the road type determination unit 15 determines that the driving road of the vehicle is a general road.

[0029] Note that the road type determination unit 15 does not necessarily have to determine it as a general road when it does not determine it as a motor vehicle exclusive road. The road type determination unit 15 may determine that the ramp connecting the general road and the motor vehicle exclusive road by a well-known method is the driving road of the vehicle.

[0030] [Processing of Road Type Determination Device] Hereinafter, the processing of the road type determination device 1 according to the present embodiment will be described with reference to FIG. 3. FIG. 3 is a flowchart showing an example of the road type determination process. The road type determination process is executed, for example, when a driving support function or an automatic driving function related to an expressway is set to be on by user setting. The road type determination process may be started when it is recognized that the vehicle has entered an expressway on the map by estimating the position of the own vehicle or the like.

[0031] As shown in FIG. 3, the ECU 10 of the road type determination device 1, as S10, recognizes the road sign in front of the vehicle by the road sign recognition unit 11. The road sign recognition unit 11 recognizes the road sign on the captured image based on the captured image of the front camera 2 of the vehicle. When the road sign is recognized (S10: YES), the ECU 10 proceeds to S11. When the road sign is not recognized (S10: NO), the ECU 10 ends the current road type determination process.

[0032] In S11, the ECU 10 detects the distance from the vehicle to the road sign by the distance detection unit 12. The distance detection unit 12 detects the distance based on the captured image of the front camera 2 or the detection result of the radar sensor 3 of the vehicle when the road sign is recognized by the road sign recognition unit 11.

[0033] In S12, the ECU 10 determines by the distance determination unit 13 whether the distance from the vehicle to the road sign is less than the determination threshold value. When it is determined that the distance from the vehicle to the road sign is less than the determination threshold value (S12: YES), the ECU 10 proceeds to S13. When it is not determined that the distance from the vehicle to the road sign is less than the determination threshold value (S12: NO), the ECU 10 ends the current road type determination process.

[0034] In S13, the ECU 10 determines whether the character size of the road sign is equal to or greater than the exclusive lane size by the character size determination unit 14. The character size determination unit 14 makes the above determination based on the captured image of the front camera 2 and the distance from the vehicle detected by the distance detection unit 12 to the road sign. If it is determined that the character size of the road sign is not equal to or greater than the exclusive lane size (S13: NO), the ECU 10 proceeds to S14. If it is determined that the character size of the road sign is equal to or greater than the exclusive lane size (S13: YES), the ECU 10 proceeds to S15.

[0035] In S14, the ECU 10 determines that the driving road is a general road by the road type determination unit 15. Then, the ECU 10 ends the current road type determination process. In S15, the ECU 10 determines that the driving road is an exclusive motor vehicle road by the road type determination unit 15. Then, the ECU 10 ends the current road type determination process.

[0036] According to the road type determination device 1 according to the present embodiment described above, it is determined whether the character size of the road sign is equal to or greater than the exclusive lane size, and when it is determined that the character size of the road sign is equal to or greater than the exclusive lane size, it is determined that the driving road of the vehicle is an exclusive motor vehicle road. Therefore, even when it is difficult to identify the color of the road sign due to the influence of the color filter of the front camera, it is possible to determine that it is an exclusive motor vehicle road.

[0037] Also, according to the road type determination device 1, when it is determined by the distance determination unit 13 that the distance is less than the determination threshold value, the determination of the character size of the road sign is started. Therefore, it is possible to avoid unreasonably determining the character size from the captured image at the timing when the distance between the vehicle and the road sign is far, and it is possible to suppress misjudgment of the character size.

[0038] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments. The present invention can be implemented in various forms with various changes and improvements based on the knowledge of those skilled in the art, including the above-described embodiments.

[0039] The road type determination device 1 does not necessarily have to have the distance determination unit 13. The character size determination unit 14 may start determining the character size of the road sign when the road sign is recognized by the road sign recognition unit 11 regardless of the distance between the vehicle and the road sign.

[0040] When the road type determination device 1 estimates that the road on which the vehicle is traveling is an expressway based on the own vehicle position and map information (map information including the position information of the expressway), if it is not determined that the character size of the road sign is equal to or greater than the expressway size, the road type determination device 1 may determine that the road on which the vehicle is traveling is not an expressway. Thereby, the road type determination device 1 can avoid erroneously determining that the road on which the vehicle is traveling is an expressway due to an estimation error of the own vehicle position or the like.

[0041] Instead of the own vehicle position and map information, the road type determination device 1 may estimate that the road on which the vehicle is traveling is an expressway by color recognition or character recognition of the road sign. Color recognition of the road sign can be used when the colors of the road signs for expressways and general roads are defined as in Japan. Character recognition means a process of recognizing not only the type of characters but also the meaning of a combination of characters in one word. When the road type determination device 1 detects characters indicating an expressway (for example, "highway") on the road sign, the road type determination device 1 may estimate that the road on which the vehicle is traveling is an expressway. Even if the road type determination device 1 detects characters indicating an expressway on the road sign, if it is not determined that the character size of the road sign is equal to or greater than the expressway size, the road type determination device 1 determines that the road on which the vehicle is traveling is not an expressway. Thereby, the road type determination device 1 can avoid erroneously determining that the road on which the vehicle is traveling is an expressway due to an error in color recognition or character recognition of the road sign.

[0042] In addition, even if the road type determination device 1 once estimates that the vehicle's driving road is an exclusive motorway, when it is determined that the vehicle's driving road is not an exclusive motorway based on the determination of the character size, the driver may be asked whether the driving road is an exclusive motorway. When the driver answers that it is an exclusive motorway by means of touch panel operation or voice input, etc., driving support or automated driving for the exclusive motorway may be permitted. If the driver does not answer that the driving road is an exclusive motorway, the road type determination device 1 does not permit the execution of driving support or automated driving for the exclusive motorway.

Explanation of Signs

[0043] 1…Road type determination device, 2…Front camera, 3…Radar sensor, 10…ECU, 11…Road sign recognition unit, 12…Distance detection unit, 13…Distance determination unit, 14…Character size determination unit, 15…Road type determination unit.

Claims

1. A road type determination device that determines whether the driving road of a vehicle is an exclusive motor vehicle road, comprising: a road sign recognition unit that recognizes a road sign in front of the vehicle based on an image captured by a front camera of the vehicle; a distance detection unit that, when the road sign is recognized by the road sign recognition unit, detects a distance from the vehicle to the road sign based on the captured image or a detection result of a radar sensor of the vehicle; a character size determination unit that determines whether the character size of the road sign is equal to or greater than the exclusive motor vehicle road size based on the captured image and the distance from the vehicle to the road sign; a road type determination unit that determines that the driving road of the vehicle is an exclusive motor vehicle road when the character size determination unit determines that the character size of the road sign is equal to or greater than the exclusive motor vehicle road size; and the road type determination unit estimates whether the driving road is an exclusive motor vehicle road based on map information including the vehicle's own position and position information of the exclusive motor vehicle road, and when it is estimated that the driving road is an exclusive motor vehicle road and the character size determination unit does not determine that the character size of the road sign is equal to or greater than the exclusive motor vehicle road size, the driver of the vehicle is asked whether the driving road is an exclusive motor vehicle road, and when the driver answers that the driving road is an exclusive motor vehicle road, driving assistance or autonomous driving for the exclusive motor vehicle road is permitted. A road type determination device.

2. further comprising a distance determination unit that determines whether the distance from the vehicle to the road sign is less than a determination threshold value, wherein the character size determination unit starts determining the character size of the road sign when the distance determination unit determines that the distance is less than the determination threshold value. The road type determination device according to claim 1.

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