Detection device

Abstract

To accurately detect the approach of another moving body such as tailgating.SOLUTION: In the drive recorder 1, the control unit 9 detects another vehicle by detecting the non-changing area NC in which the amount of change is equal to or less than the reference value between the consecutive images obtained by continuously capturing the area behind the host vehicle, and detects that another vehicle is approaching the host vehicle when the non-changing area NC overlaps the area in the image obtained by capturing the area behind the host vehicle indicating a position closer to the host vehicle than the first threshold value. Then, the speed information acquisition unit acquires the moving speed of the host vehicle, and controller 9 changes the first threshold according to the moving speed of the host vehicle.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a detection device that detects the approach of a moving object such as a vehicle from behind. [Background technology]

[0002] Tailgating generally refers to the act of forcing a vehicle in front to give way, and is a highly dangerous act that involves shortening the distance between vehicles and approaching them abnormally.

[0003] By recording such behavior in a recording device such as a drive recorder in the vehicle being tailgated, it becomes possible to deal with problems such as rear-end collisions. Conventional drive recorders do not automatically detect tailgating, unlike collisions, so manual operations such as saving the recording are required. However, it is difficult to operate manually when being tailgated.

[0004] Patent document 1 describes that a driving assistance device determines whether another vehicle is tailgating the driver's own vehicle based on images captured by an imaging means, and further determines whether the tailgating state is continuing.If it determines that the tailgating state is continuing, it provides information about the other vehicle to the driver of the driver's own vehicle.

[0005] Patent document 2 describes that a tailgating risk determination unit calculates the risk of tailgating from the surrounding conditions, the state of the vehicle itself, and the state of other vehicles, and performs notification control and operation control based on the calculation results. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2018-112892 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-205773 Summary of the Invention [Problem to be solved by the invention]

[0007] Although Patent Documents 1 and 2 describe methods for detecting tailgating, these methods are based on a fixed inter-vehicle distance and may detect driving that is not tailgating.

[0008] One example of a problem that the present invention aims to solve is how to accurately detect the approach of other moving objects, such as tailgating drivers. [Means for solving the problem]

[0009] In order to solve the above problem, the invention described in claim 1 is characterized by comprising a detection unit that detects another moving body approaching from behind a moving body, a detection unit that detects that the other moving body is closer to the moving body than a first threshold, a movement speed acquisition unit that acquires the movement speed of the moving body, and a control unit that changes the first threshold according to the movement speed of the moving body.

[0010] The invention described in claim 8 comprises a detection device described in any one of claims 1 to 7 and a recording unit that records an image captured behind the moving body, and is characterized in that the recording unit records the image when the detection unit detects that another moving body is approaching behind the moving body.

[0011] The invention described in claim 10 is a detection method executed by a detection device that detects the approach of a moving body from behind, characterized in that it includes a detection step of detecting another moving body approaching from behind the moving body, a detection step of detecting that the other moving body is closer to the moving body than a first threshold, a movement speed acquisition step of acquiring the movement speed of the moving body, and a control step of changing the first threshold in accordance with the movement speed of the moving body.

[0012] The invention as set forth in claim 11 is characterized in that the detection method as set forth in claim 10 is executed by a computer.

[0013] The invention as set forth in claim 12 is characterized in that the detection program as set forth in claim 11 is stored. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a functional configuration diagram of a drive recorder including a detection device according to an embodiment of the present invention; [Figure 2] 2 is a flowchart of the operation of the drive recorder shown in FIG. 1. [Figure 3] 10 is an explanatory diagram of an area for detecting the approach of another vehicle and a second threshold value. FIG. [Figure 4] FIG. 10 is an explanatory diagram of a non-change region. DETAILED DESCRIPTION OF THE INVENTION

[0015] A detection device according to one embodiment of the present invention will be described below. In the detection device according to one embodiment of the present invention, a detection unit detects another moving object approaching from behind a moving object, and the detection unit detects that the other moving object is closer to the moving object than a first threshold. A movement speed acquisition unit acquires the movement speed of the moving object, and a control unit changes the first threshold according to the movement speed of the moving object. In this way, the first threshold can be changed according to the movement speed of the moving object, so the distance at which approach is detected can be changed depending on the traveling speed, and the approach of another moving object, such as tailgating, can be detected with high accuracy.

[0016] The detection unit may also detect other moving objects by detecting a non-changed area where the change index value is equal to or less than a reference value between successive images captured behind the moving object. Since the other moving object follows the moving object, such as the subject vehicle, and travels at approximately the same speed, the area in the image corresponding to the other moving object becomes a non-changed area. Therefore, the other moving object can be detected by detecting the change between the successive images. Therefore, it is not necessary to use a complex algorithm for object recognition of the other moving object, and the other moving object can be detected in a simple manner.

[0017] Furthermore, the detection unit may detect that another moving object is approaching the moving object when the non-changing region overlaps with a region in an image captured behind the moving object that indicates a position closer to the moving object than the first threshold. In this way, the approach of another moving object can be detected based on the position of the non-changing region in the image.

[0018] The detection unit may also divide the captured image into multiple regions and detect unchanged regions from the multiple regions, thereby further simplifying the process of detecting changes between previous and next images.

[0019] The system may further include a lane setting unit that sets the lane area in which the moving object is traveling in images captured consecutively from behind the moving object, and the detection unit may detect non-changed areas within the lane area set by the lane setting unit. This makes it possible to exclude moving objects traveling in adjacent lanes on a road with multiple lanes. This allows for more accurate detection of the approach of other moving objects.

[0020] Furthermore, an alarm unit may be provided that warns a passenger of the moving body when the detection unit detects that another moving body is closer to the moving body than a second threshold value after detecting that the other moving body is closer to the moving body than a first threshold value. In this way, it is possible to warn the passenger of the moving body that they need to take action.

[0021] The second threshold value may be changed according to the moving speed of the moving object. In this way, the second threshold value can be changed according to the moving speed of the moving object, so that the warning distance can be changed according to the traveling speed, and the warning can be issued with high accuracy.

[0022] Furthermore, an image recording device according to one embodiment of the present invention includes the above-described detection device and a recording unit that records an image captured from behind a moving object, and the recording unit records an image when the detection unit detects that another moving object is approaching behind the moving object. By doing so, it is possible to accurately detect and record the approach of another moving object, such as a tailgating driver.

[0023] Furthermore, when the detection unit detects that another moving object is approaching behind the moving object, the recording unit may record images from a time that predates the detection by a predetermined time. This allows images to be recorded before the approach of the other moving object is detected. Therefore, the status of the other moving object can be recorded for a longer period of time.

[0024] In addition, a detection method according to one embodiment of the present invention includes a detection step of detecting another moving object approaching from behind a moving object, and a step of detecting that the other moving object is closer to the moving object than a first threshold. Then, a movement speed acquisition step of acquiring the movement speed of the moving object, and a control step of varying the first threshold according to the movement speed of the moving object. This allows the first threshold to be varied according to the movement speed of the moving object, thereby varying the distance at which approach is detected depending on the traveling speed, and enabling accurate detection of approaching moving objects, such as tailgating.

[0025] Furthermore, the above-described detection method is executed by a computer. By doing so, the first threshold value can be changed according to the moving speed of the moving object using the computer, so that the distance at which approach is detected can be changed according to the traveling speed, and the approach of other moving objects such as tailgating can be detected with high accuracy.

[0026] The detection program may be stored in a computer-readable storage medium, which allows the program to be distributed as a standalone program rather than being incorporated into a device, and allows for easy version upgrades. [Example]

[0027] An image recording device including a detection device according to one embodiment of the present invention will be described with reference to Figures 1 to 4. A drive recorder 1 as an image recording device according to this embodiment is installed in a mobile body such as an automobile.

[0028] As shown in FIG. 1, the drive recorder 1 includes a speed information acquisition unit 2, a camera 3, an acceleration sensor 4, an operation unit 5, a display 6, an internal memory 7, an external memory 8, and a control unit 9.

[0029] The speed information acquisition unit 2 is connected to, for example, the vehicle's ECU (Electronic Control Unit) via wired or wireless communication and acquires information on the vehicle's traveling speed (travel speed). That is, the speed information acquisition unit 2 functions as a traveling speed acquisition unit that acquires the traveling speed of a moving body. The speed information acquisition unit 2 is not limited to acquiring information on the vehicle's traveling speed from the vehicle, but also has a function to detect the vehicle's position using a GPS (Global Positioning System) or the like, and calculates the traveling distance per unit time from the information. The traveling speed may be calculated and acquired.

[0030] Camera 3 is a camera that captures images behind the vehicle. In this embodiment, camera 3 captures moving images. Camera 3 is attached to a location that can capture images behind the vehicle. For example, it is preferable to attach it to the rear end of the vehicle body or the rear end of the passenger compartment. However, it may also be attached to, for example, the windshield, as long as it can capture images in a range that can detect other vehicles approaching from behind the vehicle. Note that when camera 3 is attached to the rear end of the vehicle body or the rear end of the passenger compartment, it may be configured separately from the operation unit 5, display 6, etc., and connected by a cable, etc.

[0031] The acceleration sensor 4 detects the acceleration applied to the drive recorder 1, i.e., the acceleration of the vehicle. If the acceleration detected by the acceleration sensor 4 is equal to or greater than a predetermined value, it is determined that an impact has been applied to the vehicle, and the image recorded in the internal memory 7 is recorded as an event recording in the holding area of ​​the external memory under control of the control unit 9. When the image is recorded as an event recording in the holding area, it is retained without being erased by overwriting or the like.

[0032] The operation unit 5 is an interface for accepting various operations on the drive recorder 1, and includes, for example, an operation button, a remote controller, a power switch, and the like.

[0033] The display 6 is configured by, for example, a liquid crystal display. The display 6 can display images captured by the camera 3, images recorded in the external memory 8, etc. The display 6 also displays information indicating a warning, which will be described later.

[0034] The internal memory 7 is a storage area that functions as an image buffer or the like for temporarily storing images captured by the camera 3. The internal memory 7 may be a volatile memory or a non-volatile memory.

[0035] Images temporarily stored in the internal memory 7 are transferred to and recorded in the external memory 8 under the control of the control unit 9. That is, the external memory 8 functions as a recording unit that records images captured behind the moving object. The external memory 8 is a storage medium such as an SD card, and is attached to a slot or the like (not shown). Therefore, the external memory 8 is removable. The external memory 8 has a non-retention area and a retention area. The non-retention area is an area where images transferred from the internal memory 7 are recorded, but once all images in that area are recorded, the oldest images are overwritten. The retention area is an area used during the event recording described above, and is not overwritten.

[0036] The control unit 9 is composed of a CPU (Central Processing Unit) etc. The control unit 9 detects whether another vehicle is approaching behind the vehicle based on the image captured by the camera 3. If the control unit 9 detects that the other vehicle is getting closer after the detection, it issues a warning to the passengers (driver etc.) of the vehicle using the display 6 etc.

[0037] The speed information acquisition unit 2 and the control unit 9 constitute a detection device according to an embodiment of the present invention.

[0038] Next, a method for detecting the approach of another vehicle (detection method) in the drive recorder 1 configured as described above will be described with reference to the flowchart in Fig. 2. The flowchart in Fig. 2 is mainly executed by the control unit 9. This flowchart can be configured as a program executed by the CPU of the control unit 9 to become a detection program. This detection program is not limited to being stored in the memory or the like of the control unit 9, but may also be stored in a storage medium such as a memory card or an optical disk.

[0039] First, the control unit 9 acquires traveling speed information from the speed information acquisition unit 2 (step S1), and determines whether the traveling speed indicated by the acquired traveling speed information is 30 km / h or higher (step S2).

[0040] If the result of the determination in step S2 is less than 30 km / h (step S2: NO), the control unit 9 determines whether the engine is OFF (step S13). If the engine is OFF, the flow chart ends (step S13: YES). On the other hand, if the engine is ON, the process returns to step S1 (step S13: NO). This step S2 is excluded in order to avoid erroneous detection, since vehicles generally tend to be close to each other when traveling at low speeds. In FIG. 2, the standard for low speed traveling is set to 30 km / h, but it may also be another speed such as 20 km / h. Furthermore, the ON / OFF state of the engine in step S13 may be detected, for example, by operating the ignition switch or engine start button.

[0041] Next, if the result of the determination in step S2 is 30 km / h or higher (step S2: YES), the control unit 9 determines whether the traveling speed acquired in step S1 is 30 km / h or higher and lower than 100 km / h (step S3). If the traveling speed is 30 km / h or higher and lower than 100 km / h, the control unit 9 subtracts 15 from the traveling speed and sets the value obtained as the first threshold for the inter-vehicle distance (step S4). On the other hand, if the traveling speed is not 30 km / h or higher and lower than 100 km / h, the control unit 9 sets the acquired traveling speed value as the first threshold for the inter-vehicle distance (step S5). This first threshold is a threshold indicating a reference for the inter-vehicle distance between the host vehicle and another vehicle traveling behind. The control unit 9 changes this first threshold depending on the traveling speed. For example, if the traveling speed is 50 km / h, the first threshold is set to 35 m (50-15), and if the traveling speed subsequently changes to 55 km / h, the first threshold is changed to 40 m (55-15).

[0042] The method of setting the first threshold value set in steps S4 and S5 is what is generally referred to as (traveling speed value - 15) m for ordinary roads and (traveling speed value) m for expressways, but this is just one example and other methods may be used. Also, in step S5, a speed of 100 km / h or more is set as the inter-vehicle distance on an expressway, but if the vehicle's position is acquired using GPS or the like and it is detected that the vehicle is traveling on an expressway, the first threshold value may be set to (traveling speed value) m even if the vehicle is traveling at a speed less than 100 km / h. Alternatively, the drive recorder 1 may acquire map information and determine the type of road (expressway, ordinary road, zone 30, etc.) on which the vehicle is traveling from the map information, and then determine the first threshold value based on the determination result.

[0043] Returning to the explanation of Fig. 2, after setting the first threshold, the control unit 9 determines an area for detecting the approach of another vehicle and a second threshold (step S6). The area for detecting the approach of another vehicle and the second threshold will be explained with reference to Fig. 3.

[0044] FIG. 3 is an example of an image captured behind the vehicle. FIG. 3 shows a road with three lanes on each side. A truck V1 is traveling in lane L1 on the left side of the figure. In lane L2 in the center, the vehicle itself and, behind the vehicle, a passenger car V2 as another moving body (other vehicle) are traveling. No vehicles are traveling in lane L3 on the right side of the figure.

[0045] In FIG. 3, the area of ​​lane L2 in which the vehicle is traveling and the area below the first threshold value in the image is defined as detection area D. Since FIG. 3 shows an image captured from behind the vehicle, detection area D indicates a position close to the vehicle. To determine this detection area, first, the lane in which the vehicle is traveling is recognized. For example, the vehicle is stopped in advance on a lane of a predetermined road or the like so as not to interfere with other traffic, and a line LE indicating the lane boundary line on the left side of the lane and a line RI indicating the lane boundary line on the right side of the lane are set manually, for example, using the operation unit 5. In other words, the operation unit 5 functions as a lane setting unit that sets the lane area in which the moving object is traveling. Note that the lane area may also be set by automatically recognizing white lines and the like.

[0046] The detection area is the area below the line indicating the first threshold value, which is the area indicating the lane the vehicle is traveling in. The first threshold value is set at a distance of 35 m, as described above, and the position in the image corresponding to this distance can be determined from the installation height and angle of view of the camera 3, and the angles of the lines LE and RI in the image, etc.

[0047] Next, the second threshold will be described. The second threshold is set at a position closer to the host vehicle than the first threshold, targeting the area indicating the lane on which the host vehicle is traveling. In other words, in the image, the second threshold is set further below the line indicating the first threshold. This second threshold is a threshold that serves as a reference for issuing a warning to the driver or other passengers of the host vehicle. In other words, if another vehicle approaches closer than the second threshold, it is deemed to be a dangerous situation and the driver or other passengers are urged to take action. Note that the distance of this second threshold may be any distance that indicates a position closer than the first threshold, and may be set appropriately, for example, to half the distance of the first threshold. Furthermore, like the first threshold, the second threshold also varies depending on the traveling speed of the host vehicle. In other words, if the host vehicle is traveling on an ordinary road, the second threshold may be set to (traveling speed value - 15) / 2 m, and on an expressway, the second threshold may be set to (traveling speed value) / 2 m. Of course, the road type may also be determined based on GPS or map information.

[0048] Returning to the explanation of Fig. 2, once the setting of the detection area D and the second threshold has been completed, it is determined whether or not a non-changing area has been detected within the detection area D (step S7). Here, the non-changing area will be explained with reference to Fig. 4. The non-changing area refers to an area in which the change between successive images in the images (video) captured by the camera 3 is equal to or less than a reference value.

[0049] In FIG. 4, if truck V1 and standard vehicle V2 are traveling at the same speed as the host vehicle, the areas of truck V1 and standard vehicle V2 do not change between frames (before and after images) of the video captured by camera 3. This unchanged area is called non-changing area NC. On the other hand, areas other than non-changing area NC, such as cityscapes, change with the movement of the host vehicle and are called changing area C. Therefore, within the lane in which the host vehicle is traveling as shown in FIG. 3, the area that becomes non-changing area NC can be estimated to be another vehicle following behind the host vehicle. In other words, the control unit 9 functions as a detection unit that detects another moving object approaching from behind the moving object.

[0050] If the non-changed area NC is located closer than the first threshold, that is, below the line indicating the first threshold in the image (if it overlaps with the detection area D), it can be estimated that there is a vehicle approaching behind the vehicle. That is, the control unit 9 functions as a detection unit that detects that another moving object is closer to the moving object than the first threshold. If the non-changed area NC overlaps with an area in the image captured behind the moving object that indicates a position closer than the first threshold, the control unit 9 detects that the other moving object is approaching the moving object.

[0051] 4, for ease of understanding, the explanation has been given of a region without change, but if the region is strictly without change, it may not be possible to detect a region indicating another vehicle, so a reference value for the amount of change may be set and a region below that reference value may be considered a non-change region. Also, the previous and next images are not limited to being spaced apart by one frame, and may be spaced apart by multiple frames.

[0052] Alternatively, the image may be divided into predetermined cells, and whether or not each cell is a non-changed region may be determined. In this case, it is sufficient to determine whether the amount of change in each cell is below a reference value (e.g., how many pixels have no change in value). That is, the control unit 9 may divide the captured image into multiple regions and detect non-changed regions for each of the multiple regions. This simplifies the process of detecting changes between previous and next images.

[0053] Returning to the explanation of Figure 2, if no non-changing area is detected within the detection area D (step S7: NO), the process returns to step S1. On the other hand, if a non-changing area is detected within the detection area D (step S7: YES), the control unit 9 starts event recording (step S8). That is, the event is automatically recorded in a holding area of ​​the external memory 8 that will not be overwritten. That is, the control unit 9 records an image when it detects that another moving object is approaching from behind the moving object.

[0054] Next, the control unit 9 determines whether the non-changed region is located closer to the host vehicle than the second threshold value or whether the non-changed region is continuously within the detection area D (step S9). If the non-changed region is located closer to the host vehicle than the second threshold value or is continuously within the detection area D (step S9: YES), the control unit 9 issues an alert to passengers of the host vehicle, such as the driver (step S10). The alert may be issued not only by displaying an alert on the display 6, but also by sound, flashing of a lamp, or the like. The standard for determining whether the vehicle is continuously within the detection area D may be set appropriately, such as three minutes or more. That is, if the control unit 9 detects that another moving object is closer to the moving object than the first threshold value and then detects that the moving object is closer to the moving object than the second threshold value, it issues an alert to passengers of the moving object.

[0055] Next, the control unit 9 determines whether the non-changed area is not located closer to the vehicle than the second threshold value or is not continuously present in the detection area D (step S9: NO), or whether a non-changed area has been detected within the detection area D after the warning was issued in step S10 (step S11). If a non-changed area is detected within the detection area D (step S11: YES), the process returns to step S9. On the other hand, if a non-changed area is not detected within the detection area D (step S11: NO), the control unit 9 stops the event recording (step S12). Note that in step S12, the event recording may not be stopped immediately but may be stopped after a certain period of time. In step S12, the event recording is ended because the other vehicle has moved away or has left the detection area D by changing into another lane, turning right or left, etc.

[0056] As is clear from the above description of the flowchart, step S1 functions as a moving speed acquisition step, steps S4 and S5 function as control steps, and step S7 functions as a detection step and a sensing step, respectively.

[0057] According to this embodiment, the drive recorder 1 detects other vehicles by detecting a non-changed area NC where the amount of change is equal to or less than a reference value between successive images captured by the control unit 9 of the area behind the vehicle. If the non-changed area NC overlaps with an area in the captured image of the rear that indicates a position closer to the vehicle than a first threshold, the drive recorder 1 detects that the other vehicle is approaching the vehicle. The speed information acquisition unit acquires the traveling speed of the vehicle, and the control unit 9 varies the first threshold depending on the traveling speed of the vehicle. This allows the first threshold to be varied depending on the traveling speed of the vehicle, thereby varying the distance at which approach is detected depending on the traveling speed, thereby enabling accurate detection of approaching moving objects such as tailgating.

[0058] Furthermore, since other vehicles are traveling following the subject vehicle and traveling at approximately the same speed, the area of ​​the image covering the other vehicle becomes a non-changed area NC. Therefore, other vehicles can be detected by detecting changes between the previous and next images. This eliminates the need for complex algorithms for object recognition of other vehicles, and allows other moving objects to be detected in a simple manner. Furthermore, the approach of other vehicles can be detected based on the position of the non-changed area NC in the image.

[0059] Furthermore, the control unit 9 is provided with a display 6 that warns the occupants of the host vehicle when it detects that another vehicle is closer to the host vehicle than the second threshold after detecting that the other vehicle is closer to the host vehicle than the first threshold. This makes it possible to warn the occupants of the host vehicle that they need to take action. Furthermore, since the second threshold is changed according to the traveling speed of the host vehicle, the distance at which the warning is issued can be changed depending on the traveling speed, allowing for accurate warning.

[0060] In addition, the control unit 9 sets the lane area in which the vehicle is traveling in the images taken continuously behind the vehicle, and detects the non-change area NC within the set lane area. By doing so, it is possible to exclude other vehicles traveling in adjacent lanes on roads with multiple lanes. Therefore, it is possible to more accurately detect the approach of other vehicles.

[0061] Furthermore, the drive recorder 1 starts event recording when the control unit 9 detects that another vehicle is approaching behind the vehicle. This allows the drive recorder 1 to accurately detect and record the approach of another vehicle, such as tailgating.

[0062] In the above-described embodiment, when event recording is started, images may be recorded from a time that is a predetermined time before the detection. This is possible because images for a certain period of time are always recorded in the internal memory 7, and images recorded in the internal memory 7 at the time of detection are recorded in the holding area of ​​the external memory 8. In this way, images can be recorded before the approach of another vehicle is detected. Therefore, the state of the other vehicle can be recorded for a longer period of time.

[0063] Furthermore, the present invention is not limited to the above-described embodiments. That is, a person skilled in the art can implement various modifications in accordance with conventional knowledge without departing from the gist of the present invention. As long as such modifications still include the detection device of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0064] 1. Drive recorder (image recording device) 2 Speed ​​information acquisition unit (moving speed acquisition unit) 3 Camera 5 Operation unit (lane setting unit) 6 Display (alarm section) 7. Internal memory 8 External memory (recording unit) 9 Control unit (detection unit, detection unit, control unit) 10. Detection Device

Claims

[Claim 1] a detection unit that detects another moving object approaching from behind the moving object; a detection unit that detects that the other moving body is closer to the moving body than a first threshold; a movement speed acquisition unit that acquires a movement speed of the moving object; a control unit that changes the first threshold value in accordance with a moving speed of the moving object; A detection device comprising:

Images