JP4930432B2 - Vehicle periphery monitoring device - Google Patents

Description

  The present invention relates to a vehicle periphery monitoring device that displays a nose view image obtained by imaging the side of a vehicle on a monitor screen, and more particularly to a vehicle periphery monitoring device that can display only when necessary.

  When a vehicle enters an intersection while traveling on a relatively narrow road, the driver's seat has poor visibility of the intersection road on the side area side at the vehicle front position. Therefore, in order to confirm the safety when the vehicle enters the intersection, a scene in the side area at the front position of the vehicle is imaged by a camera (nose view camera) built in the front of the vehicle, and the side image is displayed. A vehicle periphery monitoring device is employed that displays the above on a monitor provided in the driver's seat of the vehicle.

  For example, in the vehicle periphery monitoring device disclosed in Patent Document 1, the right-and-left direction image on the side of the intersecting road intersecting the road on which the vehicle is traveling is displayed at an appropriate ratio according to the road attribute of the intersecting road obtained by using the navigation. By displaying, the situation of the intersection road is confirmed based on the display image of the display ratio. Further, in the nose view monitor device disclosed in Patent Document 2, an approaching moving object is detected from a side image (nose view image), and an image portion of the approaching moving object such as a vehicle is surrounded by a frame, or a predetermined window region By enlarging and highlighting, it is possible to easily recognize the presence of an approaching moving object from the side image.

JP 2006-119904 A JP 2005-123968 A

In the vehicle periphery monitoring device of Patent Document 1 described above, the left-right direction image of the intersecting road is displayed at a ratio according to the road attribute of the intersecting road, and the nose view monitor device of Patent Document 2 displays an approaching moving object from the side image. When the vehicle enters the intersection, the left and right images of the intersection road are always displayed on the monitor screen.
By the way, the in-vehicle monitor device is often used also as a display screen of a navigation device, an audio device, or the like, which is another device mounted on the vehicle. For this reason, in order to effectively use the monitor screen, it is desirable to suppress unnecessary display and give priority to necessary image display.

From such a viewpoint, when a vehicle enters an intersection, in the devices such as Patent Documents 1 and 2 that determine the display timing of the monitor screen based on the recognition of the intersection and the speed reduction of the host vehicle speed, Even when the vehicle is stopped at an intersection where a relatively wide left-right view is good, a left-right image on the cross road side is displayed on the monitor screen.
Thus, when the width of the road on which the host vehicle is traveling is relatively wide, the left-right visibility of the intersection road at the intersection is relatively good. Even in such an intersection with good left-right visibility, the vehicle periphery monitoring device used in the devices of Patent Documents 1 and 2 displays an image in the left-right direction of the intersection road side on the screen, which is substantially unnecessary. Display is in progress. In addition, the monitor displaying the screen on the cross road side interrupts the display of the other in-vehicle devices, and tends to be recognized as displaying an annoying image for the driver. In addition, a navigation system needs to be combined with a navigation system, and as the device becomes more complicated, the cost is likely to increase. If the map accuracy is low, display in an appropriate situation may not be achieved.

Furthermore, if it is a simplified device that displays the left and right images of the intersection road side only by the own vehicle speed, in this case, if you enter a low speed during a traffic jam while driving in a place other than the intersection, unnecessary sideways Since the image is displayed and the image display is troublesome for the driver, improvement is desired.
Note that even when the vehicle periphery monitoring device has an approaching object detection function as in Patent Document 2, unnecessary image display is performed at an intersection with a good left-right view, and improvement is desired.

  The present invention has been made in consideration of such circumstances, and the purpose of the present invention is only when a nose view image obtained by imaging the side of the vehicle enters an intersection from a narrow road with poor visibility in the left-right direction. An object of the present invention is to provide a vehicle periphery monitoring device capable of eliminating useless display while ensuring safety by displaying on a monitor screen.

  According to a first aspect of the present invention, there is provided a vehicle speed detecting means for detecting a vehicle speed, a nose view camera that is attached to a front portion of the vehicle and images a field of view in a vehicle width direction, and the nose view camera. A monitor capable of displaying a captured side image on a screen, road width calculation means for calculating a road width during traveling from the vehicle speed and an angle of view of the side image that is the same as the side image, and the vehicle traveling Road width determining means for determining whether the width of the road is equal to or less than a road width set to cause poor visibility when the vehicle reaches an intersection, and the vehicle speed is equal to or less than a predetermined low vehicle speed immediately before stopping And an image display control means for displaying the side image on the monitor when the width of the running road is equal to or less than the poor visibility road width.

  According to a second aspect of the present invention, in the vehicle periphery monitoring device according to the first aspect, the road width calculating means extracts a feature point from the side image and then calculates a moving speed of the feature point on the screen. It is calculated, the distance to the subject is obtained from the moving speed of the feature point, the vehicle speed, and the camera angle of view, and the road width is estimated based on the distance.

  The invention according to claim 3 is the vehicle periphery monitoring device according to claim 1, wherein the image display control means approaches the vehicle based on the side image when the side image is displayed on the monitor. It has a function as highlighting means for detecting a moving object to be displayed and highlighting an image of the moving object on the screen of the monitor.

  According to the first aspect of the present invention, even when the vehicle speed is less than a predetermined low vehicle speed and is close to stopping, for example, when reaching the intersection, poor visibility when the width of the road on which the vehicle is traveling reaches the intersection. Since the side image is displayed on the monitor only when the width is less than or equal to the width leading to the road, even if the intersection is reached while driving on a wide road, that is, when an intersection with a good line of sight is reached, it is unnecessary and troublesome. It is possible to prevent the way image from being displayed on the monitor screen and to use the screen as a display screen for other in-vehicle devices, and it is not necessary to take in road width information from a separate means, thereby simplifying the apparatus.

  Since the road width information is extracted from the moving speed of the feature point, the own vehicle speed, and the camera angle of view from the feature point extracted from the side image, the invention of claim 2 does not require special detection means, Simplification and cost increase can be prevented.

  The invention of claim 3 highlights the moving object approaching the vehicle on the monitor screen only when the road width is equal to or less than the poor visibility road width, so that the approaching moving object at the intersection can be reliably grasped, Safety can be improved.

Hereinafter, a vehicle periphery monitoring device according to an embodiment of the present invention will be described.
FIG. 1 shows a schematic configuration diagram of a main part of a vehicle periphery monitoring device according to this embodiment. The vehicle periphery monitoring device includes a pair of left and right nose view cameras 1 incorporated in the front portion of the vehicle C to capture the vehicle width direction field of view of the vehicle, and vehicle speed detection means for detecting the speed Vc of the vehicle C ( Hereinafter, simply referred to as a vehicle speed sensor) 2, a nose view switch 3 that issues a display command from the nose view camera 1, a monitor 4 that displays left and right side images VL and VR (for example, FIGS. 4 and 5), A nose view control device 5 is provided for controlling the left and right side images VL and VR captured by the nose view camera 1 and displaying them on the monitor 4.

The nose view camera 1 captures a scene entering the left and right side field of view, and includes CCD cameras incorporated on both sides of the front end position of the vehicle C, and has a predetermined left and right field of view at the vehicle front position. It functions to shoot side images in the areas FL and FR. The vehicle speed sensor 2 may be a means for detecting the axle rotation speed and detecting the vehicle speed Vc information from the same information, and may be set as a circuit for taking in the vehicle speed Vc information that a travel control device (not shown) of the vehicle has in some cases.
The nose view switch 3 is a main switch that switches the vehicle periphery monitoring device between on and off by an on / off operation, and is provided in a power supply circuit 6 such as the nose view control device 5.
The monitor 4 that displays the left and right side images VL and VR is supported by an instrument panel in the front part of the passenger compartment, and the screen is divided into left and right parts that are captured by a pair of left and right nose view cameras 1. Side images (nose view images) VL and VR are displayed in parallel.

The nose view control device 5 captures the side images (nose view images) VL and VR captured by the nose view camera 1, the vehicle speed Vc is equal to or lower than a predetermined low vehicle speed Vc1 (≧ Vc) immediately before stopping, and Control is performed so that the side images VL and VR are displayed on the monitor only when the width B of the running road is equal to or less than the poor visibility road width B1 (≧ B).
The nose view control device 5 includes an electronic control unit (MPU) mainly composed of a microcomputer. As shown in FIG. 2, the nose view control device 5 includes control functions as road width calculation means A1, road width determination means A2, and image display control means A3.
The road width calculation means A1 extracts the feature point Pan (for example, see FIG. 4) from the left and right side images VL and VR, and then calculates the moving speed Vfn (for example, see FIG. 5) of the feature point on the screen. The distance x1 to the subject is calculated from the moving speed Vfn of the same feature point Pan, the vehicle speed Vc, and the camera angle of view α, and the road width B (= 2 × 1 + k) is estimated based on the distance x1.

Specifically, the left and right side images (nose view images) VL and VR, which are imaged using the nose view camera 1, are always executed, and the left side image VL as a representative here (see FIG. 5). A plurality of feature points Pn are detected from the above image, and the motion vector is obtained by calculating the optical flow of each of these feature points Pn.
While the vehicle speed is higher than a predetermined low vehicle speed immediately before the vehicle stops during this process, which is described later, or when traveling on a road having a poor visibility road width B1, which will be described later, the screen of the monitor 4 has left and right side images. (Nose view image) VL and VR are not displayed, but navigation information, an audio function display unit, and the like are displayed.

Here, the road width calculation means A1 first acquires the nose view images captured through the nose view camera 1 sequentially in a predetermined cycle. In the nose view image, for example, a feature point Pn whose image signal level (brightness) or hue is significantly different from the peripheral portion thereof is extracted, and an optical flow for the feature point Pn is calculated, whereby the motion vector ( The moving speed Vfn) is obtained. The optical flow calculation process will be described. Basically, a coordinate change of a feature point Pn common to a plurality of continuous nose view images captured in a predetermined cycle is detected. Here, when the coordinate in the X-axis direction, which is the horizontal direction of the feature point, has changed, the magnitude of the moving speed Vfn (coordinate change) for each feature point Pn is calculated.
For example, as shown in FIG. 3, the vehicle C here moves at a vehicle speed Vc, the nose view camera 1 mounted on the vehicle captures a side image at an angle of view α, and the nose view control device 5 stores data. Captured in the area.

The captured images are, for example, side images VL and VR as shown in FIG. 5, and move in the horizontal direction over time. In this side image, for example, as shown in FIG. 3, a feature point p1 at a distance x1 relatively close to the camera 1 and a feature point p2 at a distance x2 relatively far from the camera 1 enter the end of the angle of view α at time t0. Recognized. Thereafter, the feature point p1 moves in the width y1, the feature point p2 moves in the width y2 with the same elapsed time, passes through the camera optical axis k0 in plan view, and the feature point p1 is the feature point p2 at time t2. Respectively depart from the side image at the angle of view α at time t3.
Here, the speed v1 in the horizontal direction X in the image of the feature point p1 at the distance x1 relatively close to the camera is (= y1 / t2 = 2 * tan α * x1 / t2), and the distance x2 is relatively far from the camera. The velocity v2 in the horizontal direction X in the image of the feature point p2 is (= y2 / t3 = 2 * tan α * x2 / t3). Here, since t3 ≧ t2 and tan α is a number of 1 or less, the relationship of v2 <v1 is maintained, and the speed v1 of the object close to the camera is faster than the speed v2 of the far object.

In other words, as shown in FIG. 6A, in the side image VL captured by the camera 1 having the angle of view α mounted on the vehicle moving at the vehicle speed Vc, the feature point p0 that is very close, the feature that is relatively close Since the point p1 and the relatively distant feature point p2 move in the horizontal direction X of the side image, for example, Lx, it takes Δt0, Δt2, and Δt3 (Δt0 <Δt2 <Δt3). That is, the larger the road width, the smaller the moving speed of the feature points. Furthermore, it is considered that the degree of relative speed change of the movement speeds Vfn0, Vfn1, and Vfn2 of each feature point (an example of the speeds V1 and V2 in the horizontal direction X) increases as the angle of view α increases.
Therefore, as shown in FIG. 6 (b), in the vehicle C in which the camera 1 having a predetermined angle of view α is mounted in advance, the vehicle speed Vc is used as a parameter, and the roadside facing the camera 1 from the moving speeds Vfn0, Vfn1, and Vfn2. A map m1 for determining the distance xr to the side object wr is created, and from this, the side of the roadside according to the moving speeds Vfn0, Vfn1, and Vfn2 of the feature points (an example of the speeds V1 and V2 in the horizontal direction X). A distance xr from the parallel object wr is obtained.

By the way, a large number of feature points pn exist in the side image on the screen of the monitor 4, and clustering processing is performed so that these feature points are different from each other, in this case, velocity group division of the feature points pn is performed. In addition, the farthest group set (cluster) is extracted from the set (cluster) of the perspective difference groups that are the speed groups after the group division, and the distance x1 of the set (cluster) is set to the side of the camera and the road. Set as the distance to the object. Such processing is similarly performed on the right side image.
Further, the road width calculation means A1 can calculate the road width B (= xr1 + xr2 + k) based on the distance xr1 between the camera and the subject (side object wr), the distance xr2 between the right camera and the subject and the vehicle width k.
The road width determining means A2 sets the poorly visible road width B1 in advance so as to cause poor visibility when the width B of the road on which the vehicle is traveling reaches the intersection rc. In setting the poor visibility road width B1, the shape, that is, the vehicle width, the bonnet protrusion amount, the fender mirror mounting position, the vehicle height, and the like are taken into consideration and set in advance as a fixed value.

The image display control means A3 receives a signal that the road width determination means A2 determines that the road width B on which the vehicle is currently traveling is equal to or less than the set road width B1, and further the vehicle speed Vc is just before stopping. At a predetermined low vehicle speed Vc1 (≧ Vc) or less, that is, the vehicle decelerates just before the intersection with poor visibility, and stops with the camera in the vicinity of the front end of the vehicle body projecting on the side of the intersection where the host vehicle intersects the road on which the vehicle is traveling Or it is judged whether it is in the state of slowing down.
When the road width B is equal to or less than the set road width B1 and decelerates just before the intersection where the line of sight is bad and stops or slows down, the monitor screen in the vehicle is switched, that is, until the vehicle decelerates just before the intersection. The navigation information and the audio screen display are switched, and control is performed so that the left and right side images VL and VR captured by the nose view camera 1 are displayed on the monitor screen.
The road width monitoring control process of the nose view control device 5 which is the control means of the vehicle periphery monitoring device will be described with reference to the flowchart of FIG.

Here, basically, even when the nose view switch 3, which is the main switch of the nose view camera 1, is turned off or on, the vehicle speed Vc exceeds a predetermined low vehicle speed or exceeds the road width B1 of poor visibility. While traveling on the road, the screen of the monitor 4 does not display the left and right side images (nose view images) VL and VR, but displays navigation information, an audio function display unit, and the like.
Here, first, nose view control is started when the main switch (nose view switch) 3 of the nose view camera 1 is turned on. First, the storage means for image storage processing is sequentially rewritten with a nose view image captured via the nose view camera 1 in a predetermined cycle (step S1).
Then, in the nose view image, a plurality of feature points Pn are extracted such that the image signal level (luminance) and hue of the side object wr, for example, roadside buildings, walls, hedges, etc. are greatly different from the peripheral portions ( Step S2).

After that, the tracking process for each feature point Pn is started (step S3). Here, the moving speed Vfn of each feature point Pn, for example, the feature point p1 at a distance x1 that is relatively close to the camera, the speed v2 in each horizontal direction X at the feature point p2 at a distance x2 that is relatively far, and the speed v3 in the horizontal direction X. , Etc. are sequentially calculated.
Further, the plurality of feature points Pn are subjected to clustering processing so as to perform perspective difference, here, speed group division, and the farthest group (the velocity in the horizontal direction X is the smallest) among the set (cluster) of perspective difference groups. A group (group) is extracted (step S4). Then, using the map m1 (see FIG. 6B), the distance of the set (cluster), for example, x2 is the distance between the camera 1 and the side object wr on the road (denoted as xr in FIG. 1). Asking.
Next, in step S5, the road width B (= xr1 + xr2 + k) is estimated based on the distances xr1 and xr2 between the left and right nose view cameras 1 and the subject and the vehicle width k.

Further, in step S6, it is determined whether or not the width B of the road on which the vehicle is traveling is equal to or less than the poor visibility road width B1, and thereafter, the process proceeds to step s7. Further, when the road width B is less than the poor visibility road width B1 and reaches step s7, it is determined whether or not the vehicle speed has dropped to the vehicle speed Vc1 in a state where the vehicle stops or slows down.
Here, if the road is wider than step s7 and directly enters an intersection with good visibility, useless display is suppressed in step s9 and image switching of the monitor 4 is suppressed. Alternatively, the vehicle speed may not reach lower and reach step s9 from step s7. This is a case where the distance between adjacent large vehicles when traveling in multiple lanes is erroneously determined as a road width, or when a guardrail that does not impair the roadside view during traveling is erroneously determined. Reach. Here, the display of the monitor inside the vehicle is not switched, and unnecessary display is suppressed and necessary images are continuously displayed, so that switching to unnecessary display that is troublesome for the driver can be suppressed.

On the other hand, when the vehicle decelerates or stops just before the intersection rc with poor visibility, the process reaches step s8 from step s7. Here, the monitor screen in the vehicle is switched, the left and right side images VL and VR captured by the nose view camera 1 are displayed on the monitor screen, and control of this cycle is returned.
In this way, the left and right side images VL and VR are displayed on the monitor screen only when necessary, and the presence of the approaching vehicle cd and the pedestrian md, which are moving objects on the intersection road r1, can be easily confirmed. It is possible to enter the intersection rc safely.
Note that the highlighting process may be performed as step s10, as indicated by the two-dot difference line, following the process of displaying the left and right side images VL and VR in step s8.

  That is, when the nose view control device 5 has the function as the highlighting means A4 (indicated by a two-dot chain line in FIG. 2), in step s10, the moving object Cd approaching the vehicle is displayed on the right side based on the side image. The image is detected in the side image VL (see FIGS. 1 and 8), and the image of the approaching moving object Cd is highlighted on the screen of the monitor 4. Such highlighting control of an approaching moving object is disclosed in Patent Document 2 and will not be described repeatedly. When such an image display control means has a function as the highlight display means A4, an image of the moving object Cd approaching the vehicle C only when the road width B is not more than the poor visibility road width B1 is displayed on the monitor screen. Since highlighting is performed inside, unnecessary highlighting can be prevented, and the approaching moving object Cd at the intersection can be surely grasped when necessary, and safety can be improved.

  In the above-described embodiment, the nose view cameras 1 are provided on both sides of the front portion of the vehicle, and the road width B is calculated based on the left and right side images (nose view images) VL and VR. The configuration may be simplified by providing the nose view camera 1 on the left and right sides of the front part and calculating the road width B almost twice, and in this case, the same effect can be obtained. Can do.

1 is a schematic plan view of a vehicle including a vehicle periphery monitoring device as an embodiment of the present invention. FIG. 2 is a block diagram for explaining a control function of the vehicle periphery monitoring device of FIG. 1. It is road width calculation explanatory drawing of the vehicle periphery monitoring apparatus of FIG. FIG. 2 is a schematic front view of a monitor screen of the vehicle periphery monitoring device of FIG. 1. It is a front view which shows an example at the time of displaying a side image on the monitor screen of the vehicle periphery monitoring apparatus of FIG. FIG. 2 is an explanatory diagram of each feature point in a side image captured by the vehicle periphery monitoring apparatus in FIG. 1, (a) is a characteristic explanatory diagram of a moving speed distribution of each feature point, and (b) is a side object from the moving speed and the vehicle speed. It is a characteristic diagram of the map which calculates | requires the distance. It is a flowchart of the road width monitoring control process which the vehicle periphery monitoring apparatus of FIG. 1 performs. It is a front view which shows an example which highlighted the side image on the monitor screen of the vehicle periphery monitoring apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nose view camera 2 Vehicle speed detection means 4 Monitor alpha Angle of view wr Side object xr Distance with side object A1 Road width calculation means A2 Road width judgment means A3 Image display control means A4 Highlight display means B (≧ B1) Road Width B1 Road width set to cause poor visibility C Vehicle FL, FR Field of view Vc Vehicle speed VL, VR Side image Vc1 (≧ Vc) Low vehicle speed

Claims (3)

Vehicle speed detecting means for detecting the speed of the vehicle;
A nose view camera that is attached to the front of the vehicle and images a field of view in the vehicle width direction;
A monitor capable of displaying a side image captured by the nose view camera on a screen;
Road width calculation means for calculating a road width during traveling from the vehicle speed and the angle of view of the side image and the side image;
Road width determination means for determining whether or not the width of the road on which the vehicle is traveling is equal to or less than a road width that is set to cause poor visibility when the vehicle reaches an intersection;
Image display control means for displaying the side image on the monitor when the vehicle speed is equal to or lower than a predetermined low vehicle speed just before stopping, and the width of a running road is equal to or less than the poor visibility road width;
A vehicle periphery monitoring device comprising: The vehicle periphery monitoring device according to claim 1,
The road width calculating means extracts a feature point from the side image, calculates a moving speed of the feature point on the screen, and calculates a distance from the subject based on the moving speed of the feature point, the vehicle speed, and the camera angle of view. The vehicle periphery monitoring device is characterized in that the road width is estimated based on the distance. The vehicle periphery monitoring device according to claim 1,
When the side image is displayed on the monitor, the image display control means detects a moving object approaching the vehicle based on the side image, and highlights the moving object image on the monitor screen. A vehicle periphery monitoring device comprising a function as highlighting means.

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