Intervehicle distance control device

Abstract

To provide a technology by which a target intervehicle distance can be more appropriately set in an intervehicle distance control.SOLUTION: In an intervehicle distance control device 10, an acquisition unit 42 acquires information about a license plate of a preceding vehicle. A setting unit 44 sets a target intervehicle distance between the preceding vehicle and an own vehicle on the basis of the information of the license plate acquired by the acquisition unit 42. A control unit 48 controls the own vehicle so that the intervehicle distance between the preceding vehicle and the own vehicle is the target intervehicle distance set by the setting unit 44.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle distance control device mounted on a vehicle. [Background technology]

[0002] 2. Description of the Related Art There is known a following cruise control device that controls a host vehicle to follow a preceding vehicle so as to maintain a set target inter-vehicle distance (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5729912 Summary of the Invention [Problem to be solved by the invention]

[0004] In vehicle distance control, the vehicle distance is usually controlled to ensure a certain distance between the vehicle and the preceding vehicle based on a vehicle distance setting value set by the driver in advance. If the driver of the preceding vehicle is not familiar with the area in which the vehicle is traveling and is unfamiliar with the road conditions in the area, the driver may repeatedly suddenly decelerate when turning right or left to reach the destination. In such a situation, if the vehicle distance is relatively short, the vehicle distance control may cause the vehicle to suddenly decelerate or the driver to step on the brake pedal of the vehicle. Therefore, the driver of the vehicle may not be able to drive with confidence.

[0005] An object of the present invention is to provide a technique for more appropriately setting a target inter-vehicle distance in inter-vehicle distance control. [Means for solving the problem]

[0006] In order to solve the above problems, a vehicle-to-vehicle distance control device of one embodiment of the present invention includes an acquisition unit that acquires license plate information of a preceding vehicle, a setting unit that sets a target vehicle-to-vehicle distance between the preceding vehicle and the own vehicle based on the license plate information acquired by the acquisition unit, and a control unit that controls the own vehicle so that the vehicle-to-vehicle distance between the preceding vehicle and the own vehicle becomes the target vehicle-to-vehicle distance set by the setting unit. Effect of the Invention

[0007] According to the present invention, a technique can be provided that can more appropriately set a target inter-vehicle distance in inter-vehicle distance control. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram illustrating a functional configuration of the driving assistance system according to the embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a license plate of a preceding vehicle. [Diagram 3] 4 is a flowchart showing a process for setting a target inter-vehicle distance in the inter-vehicle distance control device of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] FIG. 1 shows a functional configuration of a driving assistance system 1 according to an embodiment. The driving assistance system 1 is mounted on a vehicle and controls the inter-vehicle distance between the vehicle itself and the preceding vehicle to approach a target inter-vehicle distance. Such inter-vehicle distance control is also called ACC (Adaptive Cruise Control). In the embodiment, the license plate information of the preceding vehicle is detected by a camera to identify whether the preceding vehicle is a rental car or the like, or is likely to have come from a region other than the region in which the preceding vehicle is traveling. If the preceding vehicle is a rental car or the like, or is likely to have come from a region other than the region in which the preceding vehicle is traveling, the target inter-vehicle distance is set longer than if not. This makes it easier to ensure the safety of the vehicle itself, since the inter-vehicle distance can be kept relatively long even in a situation in which the driver of the preceding vehicle is unfamiliar with the area, unfamiliar with the road conditions, and repeatedly decelerates suddenly when turning right and left to head to the destination. This makes it easier for the driver of the vehicle itself to drive with peace of mind.

[0010] The driving assistance system 1 includes a vehicle distance control device 10, a camera 20, a radar sensor 22, a speed acquisition unit 24, a position acquisition unit 26, an operation switch 28, an HMI (Human Machine Interface) 30, an ECU (Electronic Control Unit) 32 for braking control, and an ECU 34 for drive control.

[0011] The camera 20 periodically captures an image of the area ahead of the vehicle and supplies the captured image to the inter-vehicle distance control device 10.

[0012] The radar sensor 22 is a radar for detecting objects using millimeter waves. The radar sensor 22 periodically acquires radar wave information on objects ahead of the host vehicle and transmits the acquired radar wave information to the inter-vehicle distance control device 10.

[0013] The speed acquisition unit 24 periodically acquires the speed of the host vehicle, and supplies the acquired speed information to the inter-vehicle distance control device 10 .

[0014] The position acquisition unit 26 periodically acquires the position of the vehicle using a Global Navigation Satellite System (GNSS), and supplies the acquired position information to the inter-vehicle distance control device 10. The position acquisition unit 26 may be included in a navigation system.

[0015] The operation switch 28 is a switch for starting or stopping the vehicle distance control function, setting the vehicle distance, etc., and is provided in a position where it can be operated by the driver. The vehicle distance can be set to, for example, "long," "medium," or "short." The operation switch 28 supplies information on the operation performed by the driver to the vehicle distance control device 10.

[0016] The HMI 30 includes, for example, at least one of a MID (Multi Information Display) provided on a meter panel and a speaker, and provides various types of information to the driver.

[0017] The braking control ECU 32 controls the brakes (not shown) to control the braking force of the vehicle. The drive control ECU 34 controls a drive power source (not shown) to control the drive power of the vehicle. The drive power source includes at least one of an engine and a driving motor.

[0018] As various known configurations can be applied to the camera 20, radar sensor 22, speed acquisition unit 24, position acquisition unit 26, operation switch 28, HMI 30, braking control ECU 32, and drive control ECU 34, further explanation will be omitted.

[0019] The vehicle distance control device 10 includes an image recognition unit 40, an acquisition unit 42, a setting unit 44, a vehicle distance detection unit 46, and a control unit 48. The configuration of the vehicle distance control device 10 can be realized in hardware by the CPU, memory, and other LSI of any computer, and in software by a program loaded into the memory, but here, functional blocks realized by cooperation of these are depicted. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various forms by only hardware, only software, or a combination of these. The vehicle distance control device 10 may be configured as an ECU.

[0020] The image recognition unit 40 recognizes the license plate of the preceding vehicle based on the image supplied from the camera 20, and periodically detects the license plate information. The image recognition unit 40 detects information indicating the area where the license plate was issued and information indicating the vehicle's use from the image of the license plate, and supplies the detected information to the acquisition unit 42. As various known techniques can be applied as the image recognition process by the image recognition unit 40, detailed explanations are omitted. Below, a Japanese license plate will be explained as an example.

[0021] The image recognition unit 40 detects character information including the Land Transport Bureau code and the usage code from the license plate image. The Land Transport Bureau code is information indicating the area where the license plate was issued. The usage code is information indicating the usage of the vehicle.

[0022] Figure 2 shows an example of a preceding vehicle's license plate 80. In the example of Figure 2, the license plate 80 includes the characters "Shinagawa" as a land transport bureau code 82 and the characters "wa" as a usage code 84.

[0023] The Land Transport Bureau Code 82 is a character that is written in the upper left corner of the license plate 80, and indicates the name of the Land Transport Bureau, such as the Transport Bureau or Motor Vehicle Inspection and Registration Office, in the area where the license plate 80 was issued. Here, the Land Transport Bureau Code 82 also refers to the name of the area other than the Land Transport Bureau that is written on local numbers, etc.

[0024] The usage code 84 is a character such as hiragana or the alphabet written in the lower left corner of the license plate 80, and indicates the purpose of the automobile, such as personal use, rental use, business use, etc. A rental vehicle is a vehicle that is rented to a user, and includes rental cars and shared cars. A shared car is a vehicle used for car sharing services. The rental usage code 84 is a specified character such as "wa".

[0025] Returning to Fig. 1, the acquisition unit 42 periodically acquires information on the license plate of the preceding vehicle detected by the image recognition unit 40, and supplies the acquired information to the setting unit 44.

[0026] The setting unit 44 periodically sets a target inter-vehicle distance between the vehicle ahead and the own vehicle based on the information acquired by the acquisition unit 42. The setting process will be described below.

[0027] The setting unit 44 periodically sets a reference target inter-vehicle distance DIS (hereinafter, sometimes simply referred to as DIS) based on the set value of the inter-vehicle distance set by the operation switch 28 and the vehicle speed of the host vehicle acquired by the speed acquisition unit 24. For example, if the vehicle speed is constant, the setting unit 44 sets a longer reference target inter-vehicle distance DIS as the set value of the inter-vehicle distance set by the operation switch 28 becomes longer. For example, if the set value of the inter-vehicle distance is constant, the setting unit 44 sets a longer reference target inter-vehicle distance DIS as the vehicle speed becomes higher. As various known techniques can be applied as the process of setting the reference target inter-vehicle distance DIS, detailed explanations thereof will be omitted.

[0028] When the usage code of the license plate of the preceding vehicle indicates rental use, the setting unit 44 sets the target inter-vehicle distance to DIS×α. α is a predetermined first coefficient greater than 1. When the usage code of the license plate of the preceding vehicle indicates rental use, the preceding vehicle is a rental car or a shared car, and is a rented vehicle. In other words, when the preceding vehicle is a rented vehicle, the setting unit 44 sets the target inter-vehicle distance to be longer than when the preceding vehicle is not a rented vehicle. When the preceding vehicle is a rented vehicle, the driver of the preceding vehicle may not be familiar with the location where the preceding vehicle is traveling and may be unfamiliar with the road conditions, so it is assumed that there is a relatively high possibility that the driver will suddenly decelerate. Therefore, by increasing the target inter-vehicle distance, the safety of the vehicle can be easily ensured.

[0029] The setting unit 44 sets the target inter-vehicle distance to DIS×β when the usage code of the license plate of the preceding vehicle does not indicate rental use and the area (hereinafter referred to as the first area) indicated by the land transport bureau code of the license plate of the preceding vehicle is different from the area (hereinafter referred to as the second area) identified from the position of the vehicle acquired by the position acquisition unit 26. β is a predetermined second coefficient greater than 1. For example, the classification of the second area is determined in the same way as the classification of the first area. The setting unit 44 may set β to a larger value as the distance between the first area and the second area becomes longer. The values ​​of α and β can be appropriately determined by experiment or simulation.

[0030] For example, if the first region is different from the second region, such as when the first region is "Shinagawa" and the second region is "Toyota," the preceding vehicle may have come from another region. In other words, the setting unit 44 sets the target inter-vehicle distance longer when the preceding vehicle may have come from another region than when the preceding vehicle is a vehicle within the region in which the preceding vehicle is traveling. It is assumed that the driver of the preceding vehicle that may have come from another region is also likely to be unfamiliar with the location in which the preceding vehicle is traveling and unfamiliar with the road conditions, and therefore is relatively likely to suddenly decelerate. Therefore, by increasing the target inter-vehicle distance, the safety of the host vehicle can be more easily ensured.

[0031] When the setting unit 44 sets the target inter-vehicle distance to DIS×α or DIS×β, it outputs information indicating that the target inter-vehicle distance has been increased to the HMI 30. Upon receiving this information, the HMI 30 notifies the driver that the target inter-vehicle distance is longer than normal by at least one of displaying text or an image on the MID and outputting a sound from the speaker. This can reassure the driver. Also, the driver is less likely to feel uncomfortable even if he or she feels that the inter-vehicle distance is longer than the inter-vehicle distance he or she set.

[0032] If the usage code of the license plate of the preceding vehicle does not indicate a rental vehicle and the first region is equal to the second region, the setting unit 44 sets the target inter-vehicle distance to the DIS. The setting unit 44 supplies the set target inter-vehicle distance to the control unit 48.

[0033] The inter-vehicle distance detection unit 46 periodically detects the inter-vehicle distance between the host vehicle and a preceding vehicle based on radar wave information from the radar sensor 22. The inter-vehicle distance detection unit 46 supplies the detected inter-vehicle distance to the control unit 48.

[0034] The control unit 48 controls the host vehicle so that the inter-vehicle distance detected by the inter-vehicle distance detection unit 46 becomes the target inter-vehicle distance set by the setting unit 44. The control unit 48 derives a target driving force or a target braking force so that the inter-vehicle distance becomes the target inter-vehicle distance, and transmits the target driving force to the drive control ECU 34 and the target braking force to the brake control ECU 32. Various known techniques can be applied to control the inter-vehicle distance, so detailed explanations thereof will be omitted.

[0035] The braking control ECU 32 controls the brakes so as to realize the target braking force received from the control unit 48. The drive control ECU 34 controls the drive force source so as to realize the target drive force received from the control unit 48.

[0036] Next, a description will be given of the overall operation of the inter-vehicle distance control device 10 configured as described above. Fig. 3 is a flow chart showing the process of setting a target inter-vehicle distance by the inter-vehicle distance control device 10 of Fig. 1. The process of Fig. 3 is periodically repeated at a predetermined cycle.

[0037] The image recognition unit 40 acquires an image of the preceding vehicle captured by the camera 20 (S10) and detects license plate information from the image. If the preceding vehicle is a rental car or shared car (Y in S12), the setting unit 44 sets the target inter-vehicle distance to DIS×α (S14), and the inter-vehicle distance control device 10 ends the process of setting the target inter-vehicle distance.

[0038] If the preceding vehicle is not a rental car or shared car (N in S12), and if the preceding vehicle has a license plate from another region (Y in S16), the setting unit 44 sets the target inter-vehicle distance to DIS×β (S18), and the inter-vehicle distance control device 10 ends the process of setting the target inter-vehicle distance. If the preceding vehicle does not have a license plate from another region (N in S16), the setting unit 44 sets the target inter-vehicle distance to DIS (S20), and the inter-vehicle distance control device 10 ends the process of setting the target inter-vehicle distance.

[0039] According to the embodiment, when the driver of the preceding vehicle is likely to be unfamiliar with the road conditions in the vicinity, a target inter-vehicle distance that is easy to ensure safety can be set. In other words, a more appropriate target inter-vehicle distance can be set. Therefore, in the case of a preceding vehicle that is likely to be unfamiliar with the road conditions of the land on which it is traveling, the inter-vehicle distance is controlled to be longer than in the case of a preceding vehicle that is not, so that the influence of the driving state of the preceding vehicle on the unfamiliar road on the host vehicle can be suppressed. When the preceding vehicle suddenly decelerates, the driver of the host vehicle can be suppressed from applying the brakes.

[0040] The present invention has been described above based on the embodiments. The embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each processing step, and that such modifications are also within the scope of the present invention.

[0041] (First Modification) The image recognition unit 40 may further detect a mark indicating a rented vehicle on the rear of the leading vehicle based on the image provided by the camera 20. This mark is predetermined, and may be, for example, a logo or mark of a rental car company or a car sharing company displayed on a sticker attached to the rear of the leading vehicle. When the image recognition unit 40 detects this mark, it provides the acquisition unit 42 with information indicating that the leading vehicle has a mark indicating a rented vehicle.

[0042] The acquisition unit 42 further acquires information on whether or not the preceding vehicle has a mark indicating a rented vehicle, and supplies the acquired information to the setting unit 44. The setting unit 44 sets the target inter-vehicle distance to DIS×α not only when the usage code of the license plate of the preceding vehicle indicates a rental vehicle, but also when the preceding vehicle has a mark indicating a rented vehicle.

[0043] According to the first modification, even in a situation where the usage code of the preceding vehicle cannot be accurately detected due to reasons such as a dirty license plate, it is possible to identify that the preceding vehicle is a rented vehicle and set a long target inter-vehicle distance. Also, even in countries where license plates do not include a rental usage code, it may be possible to identify that the preceding vehicle is a rented vehicle.

[0044] (Second Modification) The acquisition unit 42 may further acquire information indicating whether the preceding vehicle has entered a predetermined driving state, and may supply the acquired information to the setting unit 44. The predetermined driving state is a driving state in which the vehicle is likely to be unfamiliar with road conditions, and includes, for example, a driving state in which sudden deceleration is repeated, a driving state in which the turn signal is repeatedly activated and deactivated, or a driving state in which the vehicle speed is equal to or less than a speed threshold when there is no other preceding vehicle in front of the preceding vehicle. The speed threshold may be, for example, about 30 km per hour, and can be appropriately determined by experiment or simulation. For example, the image recognition unit 40 detects the activation state of the turn signal of the preceding vehicle and whether there is another preceding vehicle in front of the preceding vehicle, based on an image of the preceding vehicle captured by the camera 20. The acquisition unit 42 identifies whether the preceding vehicle has entered a predetermined driving state based on the information detected by the image recognition unit 40, the information detected by the radar sensor 22, the vehicle speed of the vehicle, and the like. Various known technologies can be applied as a process for identifying whether the preceding vehicle has entered a predetermined driving state.

[0045] When the purpose code of the license plate of the preceding vehicle indicates that it is for rental, the setting unit 44 may set the target inter-vehicle distance to DIS×α×γ when the preceding vehicle reaches a predetermined driving state, where γ is a predetermined third coefficient greater than 1. When the purpose code of the license plate of the preceding vehicle indicates that it is for rental, the setting unit 44 may set the target inter-vehicle distance to DIS×α until the preceding vehicle reaches a predetermined driving state.

[0046] When the first region is different from the second region, the setting unit 44 may set the target inter-vehicle distance to DIS×β×γ when the preceding vehicle reaches a predetermined traveling state. When the first region is different from the second region, the setting unit 44 may set the target inter-vehicle distance to DIS×β until the preceding vehicle reaches a predetermined traveling state.

[0047] According to the second modification, when the preceding vehicle is a rented vehicle or the preceding vehicle is possibly from another area, and the driver of the preceding vehicle is likely to be unfamiliar with the road conditions, the target inter-vehicle distance can be set even longer. This makes it easier to ensure the safety of the vehicle.

[0048] The second modification may be combined with the first modification. [Explanation of symbols]

[0049] 1...driving assistance system, 10...vehicle distance control device, 20...camera, 22...radar sensor, 24...speed acquisition unit, 26...position acquisition unit, 28...operation switch, 30...HMI, 32...braking control ECU, 34...drive control ECU, 40...image recognition unit, 42...acquisition unit, 44...setting unit, 46...vehicle distance detection unit, 48...control unit.

Claims

[Claim 1] An acquisition unit that acquires license plate information of a preceding vehicle; a setting unit that sets a target inter-vehicle distance between the preceding vehicle and the host vehicle based on the license plate information acquired by the acquisition unit; a control unit that controls the host vehicle so that a vehicle-to-vehicle distance between the host vehicle and a preceding vehicle becomes the target vehicle-to-vehicle distance set by the setting unit; A vehicle distance control device comprising:

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