JP5476960B2 - Vehicle forward monitoring device - Google Patents

Description

  The present invention relates to a vehicle front monitoring apparatus.

  2. Description of the Related Art A vehicle forward monitoring device that monitors a state in front of a vehicle using a camera or a radar mounted on the vehicle is known. In this type of vehicle forward monitoring device, an oncoming vehicle (a vehicle that travels in front of the host vehicle in a direction opposite to its traveling direction) and a preceding vehicle (runs in front of the host vehicle in the same direction as the traveling direction). Vehicle), obstacles, pedestrians and other objects (in the present specification, these are collectively referred to as “front objects”) to detect the front of the vehicle. The detection result of the forward object by the vehicle forward monitoring device is, for example, driving support such as pre-crash safety (PCS) that minimizes the impact at the time of collision and adaptive cruise control (ACC) that keeps the distance between the preceding vehicle constant. Used in the system.

  In general, the radar has a high detection accuracy with respect to the distance to the front object, but has a characteristic that the lateral resolution is relatively low. The camera has an advantage that the lateral resolution is high and the boundary detection of the front object is easy. Therefore, for example, the radar acquires the relative distance of the front object from the host vehicle, and the camera uses information about the size of the front object and the relative lateral position when the front and rear axes of the host vehicle are used as a reference (hereinafter referred to as the following). , Etc., which are also referred to as “lateral position information”), and the like, the forward object is detected.

  The relationship between the relative distance of the front object from the host vehicle and the angle of view (viewing angle) of the camera will be described. When detecting a forward object close to the host vehicle, for example, a preceding vehicle approaching from the side by changing the lane or the like in front of the host vehicle, it is preferable to capture the front of the vehicle with a camera having a large angle of view. A camera with a large angle of view does not have a very high resolution for distant targets. Therefore, when a forward object far from the host vehicle is imaged with a camera having a large angle of view, the accuracy of boundary detection of the forward object is likely to decrease. Therefore, a pair of cameras with different angles of view are provided, and an area relatively close to the own vehicle is imaged with a camera with a larger angle of view, while an area far from the own vehicle is imaged with a camera with a smaller angle of view. Technology has also been proposed.

  By the way, when the host vehicle is approaching a curved road or when steering is performed to avoid a parked vehicle on the side of the road, it is far from the field of view (imaging range) of the narrow-angle camera with the smaller angle of view. There is a case where the front object located is displaced. In relation to this, a technique has also been proposed in which the angle formed by the camera's visual field center line with respect to the longitudinal axis of the vehicle is adjusted in accordance with steering of the vehicle (see, for example, Patent Document 1).

JP-A-9-95194 Japanese Patent Laying-Open No. 2005-81860

  However, even if the direction of the camera's visual field center line is changed following the driver's steering operation, a response delay will occur, which may impair the continuity or continuity of the monitoring system in front of the vehicle. It was.

The present invention has been made in view of the above-described problems, and the object of the present invention is to provide steering when the host vehicle is approaching a curved road or to avoid a parked vehicle on the side of the road. An object of the present invention is to provide a vehicle forward monitoring device capable of maintaining the continuity and continuity of the monitoring system ahead of the vehicle even when the vehicle is steered.

In order to solve the above problems, the vehicle forward monitoring apparatus according to the present invention employs the following means.
That is, the vehicle front monitoring apparatus according to the present invention is
An in-vehicle narrow-angle camera that images the front of the vehicle,
A vehicle-mounted wide-angle camera that has a wider angle of view than the narrow-angle camera and images the front of the host vehicle;
Any of narrow-angle image information that is image information generated by the narrow-angle camera and wide-angle image information that is image information generated by the wide-angle camera according to the relative distance between the front object existing ahead of the host vehicle and the host vehicle. Selecting means for selecting either as image information for processing which is image information used for image processing;
Image processing means for performing image processing using the processing image information selected by the selection means and detecting a forward object existing ahead of the host vehicle;
Direction deviation detection means for detecting a deviation of the angle-of-view center line direction of the narrow-angle camera with respect to the traveling direction in which the host vehicle should travel
A steering angle detector for detecting the steering angle of the steering of the host vehicle;
With
The selection means selects the narrow-angle image information as the processing image information when the relative distance is equal to or greater than a predetermined reference distance,
The direction deviation detection means detects the deviation when a change amount of the steering angle detected by the steering angle detection unit is equal to or larger than a predetermined amount determined according to the reference distance,
The selection means selects the wide-angle image information even when the image information for processing to be selected according to the relative distance is the narrow-angle image information when the deviation is detected by the direction deviation detection means. It is characterized by that.

  In the present invention, narrow-angle image information is data obtained by converting an image captured by a narrow-angle camera into an image signal, and wide-angle image information is data obtained by converting an image captured by a wide-angle camera into an image signal. Further, the relative distance of the front object from the host vehicle can be detected by, for example, a radar.

  For example, when the relative distance between the front object and the host vehicle is relatively short, the selection unit selects the wide-angle image information as the processing image information. Accordingly, it is possible to suitably detect a preceding vehicle approaching from the side of the host vehicle due to a lane change or the like, a pedestrian suddenly jumping out from the sidewalk, and the like. On the other hand, for example, when the relative distance between the front object and the host vehicle is relatively long, the narrow-angle image information is selected as the processing image information. A narrow-angle camera has a smaller angle of view than a wide-angle camera, and therefore has a longer focal length than a wide-angle camera. By detecting the forward object located far away from the host vehicle using the narrow-angle image information, it is possible to increase the accuracy in detecting the boundary of the forward object located far away.

  The selection means selects narrow-angle image information (as processing image information) when the relative distance between the front object and the host vehicle is equal to or greater than a predetermined reference distance, and a wide-angle image when the relative distance is less than the reference distance. Information can be selected (as processing image information). For example, when the image processing unit detects the front object using wide-angle image information, the reference distance is determined so that the boundary (edge) of the front object can be detected with a desired accuracy. The maximum relative distance.

  According to this configuration, when the deviation of the angle of view of the narrow-angle camera with respect to the traveling direction in which the host vehicle should travel is detected by the direction shift detection unit, the selection is made according to the relative distance between the front object and the host vehicle. Wide-angle image information is selected even when the processing image information to be processed is narrow-angle image information. The traveling direction in which the host vehicle should travel is the direction of the route in which the host vehicle is scheduled to travel, and more specifically, it can be said to be along the traveling path. For example, the traveling direction of the host vehicle when traveling on a curved road can be understood as a direction along a curved road, and the traveling direction of the host vehicle when traveling on a straight road is a direction along the straight road. Can be understood as

  When steering is performed to avoid a parked vehicle on the side of the vehicle's running road, or when the vehicle approaches a curved road, the traveling direction of the vehicle and the angle-of-view centerline of the narrow-angle camera Deviation occurs between directions. Under such circumstances, there is a high possibility that a forward object located far away from the host vehicle is out of the field of view of the narrow-angle camera. Therefore, for example, when the image information for processing to be selected according to the relative distance between the front object and the host vehicle is narrow-angle image information, such as when detecting a distant front object, the wide-angle image information is selected. Thus, it is possible to suitably avoid a situation where the front object is not detected due to being out of the field of view of the camera used.

  Therefore, according to the present invention, the continuity of the monitoring system in front of the vehicle even when the host vehicle approaches a curved road or when steering is performed to avoid a parked vehicle on the side of the road, Continuity can be maintained.

Further, in the present invention, the direction displacement sensing means, the amount of change in the steering angle is the steering angle detection unit to the thus detected to detect a steering angle of the vehicle steering, and determined the specified amount or more depending on the reference distance In this case, the deviation is detected.

  For example, the direction deviation detecting means calculates a steering amount that is a change amount of the steering angle, and when it is determined that the steering amount is equal to or greater than a predetermined amount, It may be detected that the view angle center line direction has shifted. Further, the steering amount can be grasped as a change amount of the steering angle when the neutral steering angle is used as a reference, for example. The neutral steering angle is a steering angle corresponding to the neutral position (neutral position) of the steering wheel, and the neutral position is the position when the steering wheel (handle) is just at the center. In addition, the prescribed amount here is when a forward object existing at a position corresponding to the distance at which the processing image information is just switched from the wide-angle image information to the narrow-angle image information is to be imaged by the narrow-angle camera, This can be regarded as the minimum value of the steering amount when the front object is out of the field of view of the narrow-angle camera.

In the present invention, in the case where a curvature detection unit that detects the curvature of the traveling path on which the host vehicle travels is provided, the direction deviation detection unit has a curvature detected by the curvature detection unit according to the reference distance. The deviation can be detected when the curvature is equal to or greater than a predetermined specified curvature .

  The curvature of the traveling road is an index representing the degree and degree of bending of the traveling road, and is the reciprocal of the curve radius (curvature radius). The larger the curvature of the road, the more severe (steep) the curve is. The direction deviation detecting means detects that the angle-of-view center line direction of the narrow-angle camera has deviated from the traveling direction in which the host vehicle is to travel when it is determined that the curvature of the road is equal to or greater than the prescribed curvature. good. Here, the specified curvature means that when the front object existing at a position corresponding to the distance at which the processing image information is just switched from the wide-angle image information to the narrow-angle image information is to be imaged by the narrow-angle camera, It can be grasped as the minimum value of the curvature of the travel path when it is out of the field of view of the narrow-angle camera.

  According to the vehicle front monitoring apparatus according to the present invention, even when the host vehicle is approaching a curved road or when steering is performed to avoid a parked vehicle on the side of the road, the monitoring system in front of the vehicle Continuity and continuity can be maintained.

1 is a block diagram showing a schematic configuration of a vehicle forward monitoring apparatus 1 according to an embodiment. It is the figure which illustrated each of the area | region which an image information selection part sets the image information selection flag Fg to 1, and the area | region which sets to 0. It is explanatory drawing for demonstrating the mode of the avoidance driving | running | working in which the own vehicle avoids both front road parking. It is explanatory drawing for demonstrating a mode that the own vehicle approached the curve road. 3 is a flowchart illustrating a control routine in the first embodiment. It is a block diagram which shows schematic structure of the vehicle front monitoring apparatus 1 which concerns on Example 2. FIG. 6 is a flowchart illustrating a control routine in Embodiment 2.

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be described in detail below with reference to the drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are intended to limit the technical scope of the invention only to those unless otherwise specified. is not.

  FIG. 1 is a block diagram showing a schematic configuration of a vehicle forward monitoring apparatus 1 according to the present embodiment. The vehicle forward monitoring device 1 is a device that detects the “front object” that is a generic name of other vehicles (oncoming vehicles, preceding vehicles, etc.), obstacles, pedestrians, etc. existing in front of the host vehicle and monitors the front of the vehicle. is there. And based on the monitoring result by the vehicle front monitoring apparatus 1, a pre-crash safety system (PCS) operates. For example, when it is determined that there is a high possibility that a front object and the host vehicle will collide, a warning is transmitted to the driver and collision damage reduction control is performed. The collision damage reduction control can exemplify reduction of a collision speed by winding a seat belt or pre-crash brake.

  The vehicle front monitoring apparatus 1 includes a millimeter wave radar 2, a pair of cameras 3 and 4, a steering angle sensor 5, a radar ECU 6, and a system ECU 7 having different angles of view (viewing angles). In this embodiment, when simply describing “vehicle”, it means the own vehicle.

  The millimeter wave radar 2 is provided at the front of the host vehicle, and detects the relative distance of the forward object existing in front of the host vehicle from the host vehicle (hereinafter referred to as “object relative distance”) and the direction of the front object. To do. The millimeter wave radar 2 scans the millimeter wave in a predetermined range in front of the host vehicle and receives the reflected wave. Then, the object relative distance is detected in each direction in which the reflected wave is received. Detection by the millimeter wave radar 2 is performed every predetermined time. The millimeter wave radar 2 is electrically connected to the radar ECU 6 and sequentially outputs an electrical signal (hereinafter also referred to as “object distance information”) corresponding to the detected object relative distance of the forward object to the radar ECU 6.

  The radar ECU 6 is mainly configured by a computer including a CPU, a ROM, and a RAM, and includes an object relative distance calculation unit 61 and an object relative speed calculation unit 62. The object relative distance calculation unit 61 detects a forward object based on the object distance information from the millimeter wave radar 2. Further, the object relative distance calculation unit 61 calculates the object relative distance. The object relative distance is a relative distance between the front object and the host vehicle in the longitudinal axis direction of the host vehicle. The object relative speed calculation unit 62 calculates the relative speed of the detected front object with respect to the host vehicle. Each of the object relative distance calculation unit 61 and the object relative speed calculation unit 62 outputs a signal corresponding to the calculation result to the system ECU 7.

Of the pair of cameras 3 and 4, the camera 3 having a relatively large angle of view (viewing angle) is referred to as a “wide-angle camera”, and the camera 4 having a smaller angle of view is referred to as a “narrow-angle camera”. And The wide-angle camera 3 and the narrow-angle camera 4 have a lens, a CCD (charge-coupled device), and a CMOS.
(Complementary metal oxide semiconductor) and the like. Each of the wide-angle camera 3 and the narrow-angle camera 4 is installed in the vicinity of a stay (not shown) of a rearview mirror in the passenger compartment (driver's cab), and images a landscape in front of the host vehicle. Images in front of the vehicle captured by the wide-angle camera 3 and the narrow-angle camera 4 are sequentially output to the system ECU 7 as image information (image data) converted into image signals. Hereinafter, image information generated from an image captured by the wide-angle camera 3 is referred to as “wide-angle image information Dw”, and image information generated from an image captured by the narrow-angle camera 4 is referred to as “narrow-angle image information Dn”.

  The image capture frequency (imaging frequency) by the wide-angle camera 3 and the narrow-angle camera 4 in the present embodiment is set to be about 30 ms (milliseconds), for example. Further, the field angle (field of view) center line directions of the wide-angle camera 3 and the narrow-angle camera 4 are both parallel to the longitudinal axis of the host vehicle. Further, the front-rear axis direction and the angle-of-view centerline direction of the host vehicle may be set to be shifted, but in the present embodiment, the angle formed by the two directions is not changed according to driving conditions and driving conditions. .

  The steering angle sensor 5 is a sensor that is provided on the steering shaft of the host vehicle and detects the steering angle of the steering of the host vehicle (sometimes referred to as a turning angle). In the present embodiment, the steering angle sensor 5 corresponds to the steering angle detector in the present invention. The steering angle sensor 5 includes a rotary encoder and the like, and detects the direction and magnitude of the steering angle input by the driver of the host vehicle via a steering wheel (so-called steering wheel). That is, the direction of the steering angle is opposite when turning the steering to the right and when turning the steering to the left. The steering angle sensor 5 outputs a steering angle signal corresponding to the direction and magnitude of the detected steering angle to the system ECU 7.

  The system ECU 7 is mainly configured by a computer including a CPU, a ROM, and a RAM, and includes an image information selection unit 71, an image processing unit 72, a direction deviation detection unit 73, and a collision determination unit 74. The function of each part will be described below.

  Due to its characteristics, the radar is highly accurate in detecting the relative distance of the object on the front object, but has a relatively low lateral resolution. In contrast, the camera has excellent lateral resolution, and can accurately detect the boundary (edge) of the front object. Further, when comparing the wide-angle camera 3 and the narrow-angle camera 4, the narrow-angle camera 4 has a long focal length because of a smaller angle of view than the wide-angle camera 3, and has a higher resolution with respect to a front object located far away than the wide-angle camera 3. Are better. On the other hand, the wide-angle camera 3 has an advantage that a front object that is close to the host vehicle can be easily placed in the field of view. Therefore, the system ECU 7 uses, as object relative, image information to be subjected to image (analysis) processing for detecting a front object, that is, image information used for image processing, among the narrow-angle image information Dn and the wide-angle image information Dw. Switching is performed according to the object relative distance calculated by the distance calculation unit 61. Here, the image information used for the image processing is hereinafter referred to as “processing image information”.

  Specifically, the image information selection unit 71 selects the narrow-angle image information Dn as the processing image information when the object relative distance Dfw acquired from the object relative distance calculation unit 61 is greater than or equal to the reference distance Db. . In this case, the image information selection unit 71 sets (sets) the image information selection flag Fg to 1. The image information selection flag Fg is a storage area provided in the RAM of the image information selection unit. On the other hand, when the object relative distance Dfw is less than the reference distance Db, the image information selection unit 71 selects the wide-angle image information Dw as the processing image information, and sets (sets) the image information selection flag Fg to 0. The image information selection unit 71 outputs an image selection signal indicating which of the narrow-angle image information Dn and the wide-angle image information Dw is selected as the processing image information to the image processing unit 72. In other words, the image selection signal is a signal indicating whether the image information selection flag Fg is set to 1 or 0.

  The image processing unit 72 performs image processing using the processing image information selected by the image information selection unit 71 and detects a front object. Specifically, for example, edge detection processing is performed on the processing image information, and a front object is extracted from the image region range. Then, the front object is detected by acquiring the lateral position information related to the size of the forward object and the lateral position based on the extraction result.

  Here, instead of both the narrow-angle image information Dn and the wide-angle image information Dw, either one is selected, and the forward object is detected based on the selected image information. This is for the purpose of reducing the processing load. In addition, the reference distance Db is within the limit that can detect the boundary (edge) of the front object with desired accuracy when image processing is performed using the wide-angle image information Dw and detection of the front object is attempted. And the maximum distance of the front object.

  FIG. 2 shows each of an area where the image information selection unit 71 sets the image information selection flag Fg to 1 (indicated by diagonal hatching in the figure) and an area where the image information selection flag Fg is set to 0 (indicated by grid hatching in the figure). FIG. In the present embodiment, an area where the image information selection flag Fg is set to 1 (area where the narrow-angle image information Dn is selected as processing image information) is included in the field of view (imaging range) of the narrow-angle camera 4. Yes. An area where the image information selection flag Fg is set to 0 (an area where the wide-angle image information Dw is selected as processing image information) is included in the field of view of the wide-angle camera 3.

  In the figure, the field of view of the narrow-angle camera 4 is an area sandwiched between alternate long and short dash lines, and the field of view of the wide-angle camera 3 is an area sandwiched between alternate long and two short dashes lines. The angle of view of each of the narrow-angle camera 4 and the wide-angle camera 3 is such that a forward object far from the own vehicle is included in the field of view of the narrow-angle camera 4 and a forward object close to the own vehicle is in the field of view of the wide-angle camera 3. Each of them is set to an appropriate angle so as to be included in.

  Reference numerals “MF1” and “MF2” in the figure represent forward objects relative to the host vehicle. As illustrated, the front object MF1 has an object relative distance Dfw, which is a relative distance from the vehicle, longer than the reference distance Db. Therefore, when receiving the calculation result of the object relative distance Dfw from the object relative distance calculation unit 61, the image information selection unit 71 sets the image information selection flag Fg to 1. When the image processing unit 72 receives the image selection signal from the image information selection unit 71, the image processing unit 72 detects the front object MF1 based on the narrow-angle image information Dn. On the other hand, the front object MF2 has an object relative distance Dfw shorter than the reference distance Db. Therefore, when receiving the calculation result of the object relative distance Dfw from the object relative distance calculation unit 61, the image information selection unit 71 sets the image information selection flag Fg to 0. When the image processing unit 72 receives the image selection signal from the image information selection unit 71, the image processing unit 72 detects the front object MF2 based on the wide-angle image information Dw.

  The matters described above are the basic control contents when the vehicle front monitoring apparatus 1 according to the present embodiment monitors the front of the host vehicle. Next, characteristic control contents in the vehicle forward monitoring apparatus 1 will be described. When the forward object is located far from the host vehicle, the information selection unit 71 sets the image information selection flag Fg to 1 in accordance with the basic control. Therefore, the image processing unit that has received the image selection signal from the image information selection unit 71 72, image processing is performed using the narrow-angle image information Dn, and a forward object is detected.

  However, when the steering environment is steered to avoid a parked vehicle on the side of the traveling road of the own vehicle, and when the traveling environment of the own vehicle changes, such as when the own vehicle approaches a curve (road), the narrow angle The angle of view (field of view) center line direction Dcl of the camera 4 is deviated from the traveling direction (hereinafter referred to as “scheduled traveling direction”) Dcp of the host vehicle, and a distant front object moves from the field of view of the narrow-angle camera 4. It may come off.

FIG. 3 is an explanatory diagram for explaining a situation of avoiding traveling in which the host vehicle avoids a road parking vehicle ahead (hereinafter referred to as “both front road parking”). Here, the host vehicle travels on a straight road, and the planned traveling direction Dcp of the host vehicle traveling on the straight road coincides with the direction in which the straight road extends as shown (thick solid arrow). On the other hand, if there is both front road parking ahead of the host vehicle, this must be avoided, and the traveling environment of the host vehicle changes. That is, the steering state of the host vehicle is steered in accordance with the driver's steering operation, so that the traveling state of the host vehicle shifts to avoidance traveling that avoids both front road parking.

  Here, as described above, the relationship between the direction of the angle-of-view center line of the narrow-angle camera 4 (hereinafter referred to as “narrow-view angle center line direction”) Dcl and the front-rear axis of the host vehicle is fixed. As a result, the narrow angle-of-view center line direction Dcl changes compared to before steering, which is deviated from the planned traveling direction Dcp of the host vehicle. As a result, there is a high possibility that a front object (an oncoming vehicle in this figure) located far from the host vehicle is out of the field of view of the narrow-angle camera 4 and cannot be detected. As is clear from the description of FIG. 3, the planned travel direction Dcp means the direction in which the host vehicle should travel originally. Therefore, when the host vehicle is traveling on a straight road as shown in the figure, the direction along the straight road corresponds to the planned traveling direction Dcp, and changes temporarily following the steering of the steering during the avoidance traveling. The direction of the front / rear axis of the host vehicle does not correspond to the planned traveling direction.

  FIG. 4 is an explanatory diagram for explaining a situation in which the host vehicle has reached a curved road. In this figure, the host vehicle is traveling along a curve that turns to the right (right curve), and the planned traveling direction Dcp of the host vehicle is a direction along the curve as indicated by the solid arrow direction in the figure. When a curved road as shown in the figure appears in front of the host vehicle traveling on a straight road, the traveling environment of the host vehicle changes. In this case, as the distance from the host vehicle increases, the narrow angle center line direction Dcl (represented by a broken line arrow in the figure) shifts from the planned traveling direction Dcp along the curve. As a result, there is a high possibility that a front object (an oncoming vehicle in this figure) located far from the host vehicle is out of the field of view of the narrow-angle camera 4 and cannot be detected.

  Therefore, in the vehicle front monitoring apparatus 1 according to the present embodiment, the direction deviation detection unit 73 determines whether or not there is a deviation of the narrow angle of view center line direction Dcl with respect to the planned traveling direction Dcp of the host vehicle as described in FIGS. Is detected. When the deviation in the estimated traveling direction Dcp and the narrow-angle-of-viewline centerline direction Dcl is detected by the direction deviation detection unit 73, the image information selection unit 71 has processing image information to be selected according to the object relative distance Dfw. Even in the case of the narrow-angle image information Dn, the wide-angle image information Dw generated by the wide-angle camera 3 having a larger angle of view is selected.

  Hereinafter, examples in the present embodiment will be described. First, in the first embodiment, the contents of control when the situation described with reference to FIG. 3, that is, the deviation between the planned traveling direction Dcp of the host vehicle and the narrow-angle central line direction Dcl occurs due to the steering of the host vehicle. Will be described. Next, in the second embodiment, when the vehicle travels on a curved road or before entering the curved road, the shift between the planned traveling direction Dcp of the host vehicle and the narrow-angle center line direction Dcl is similar to that in FIG. The contents of control when this happens will be described.

  FIG. 5 is a flowchart illustrating a control routine in the first embodiment. This control routine is a routine that is repeatedly performed at regular intervals (for example, about 100 ms) in cooperation with the radar ECU 6 and the system ECU 7.

  When this routine is executed, in step S101, the object relative distance calculation unit 61 calculates the object relative distance Dfw based on the output signal from the millimeter wave radar 2, and the object to be detected by the image processing unit 72. A forward object is detected.

Next, in step S102, the image information selection unit 71 determines whether or not the object relative distance Dfw is greater than or equal to the reference distance Db. When a positive determination is made (Dfw ≧ Db), the process proceeds to step S103. If a negative determination is made in this step (Dfw <Db), the process proceeds to step S104. In step S104, the image information selection unit 71 selects the wide-angle image information Dw as the processing image information, and sets (sets) the image information selection flag Fg to 0. When the process of step S104 ends, the process proceeds to step S108.

  In step S 103, a steering angle signal is detected by the steering angle sensor 5, and the detection result is input to the direction deviation detection unit 73. Then, the direction deviation detection unit 73 calculates a steering angle change amount (hereinafter referred to as “steering amount”) θst based on a steering angle signal representing the direction and magnitude of the steering angle. Here, the steering amount θst is a change amount of the steering angle when the neutral steering angle is used as a reference. The neutral steering angle is a steering (steering) angle corresponding to the neutral position (neutral position) of the steering wheel, and the neutral position is a position when the steering wheel is exactly at the center.

  In a succeeding step S105, it is determined whether or not the steering amount θst is equal to or larger than the specified steering amount θstb. The prescribed steering amount θstb is that when a front object whose object relative distance Dfw is exactly the reference distance Db with respect to the host vehicle is to be imaged by the narrow-angle camera 4, the front object is out of the field of view of the narrow-angle camera 4. Is defined as the minimum value of the change amount of the steering angle. In the present embodiment, the steering angle sensor 5 corresponds to the steering angle detector in the present invention. In the present embodiment, the direction deviation detection unit 73 corresponds to the direction deviation detection means in the present invention.

  When a negative determination is made in this step (θst <θstb), the direction deviation detection unit 73 detects that no deviation has occurred between the planned traveling direction Dcp of the host vehicle and the narrow angle of view centerline direction Dcl, The process proceeds to S106. Here, “displacement” means that when a forward object whose object relative distance Dfw to the host vehicle is at the reference distance Db is to be imaged by the narrow-angle camera 4, the forward object is viewed from the field of view of the narrow-angle camera 4. This is equivalent to a deviation of a magnitude that is far from the limit. In step S106, in accordance with the basic control described above, the image information selection unit 71 selects the narrow-angle image information Dn as processing image information, and sets (sets) the image information selection flag Fg to 1. When the process of step S106 ends, the process proceeds to step S108.

  When an affirmative determination is made in this step (θst ≧ θstb), the direction deviation detection unit 73 detects that a deviation has occurred between the planned traveling direction Dcp of the host vehicle and the narrow angle of view centerline direction Dcl, The process proceeds to S107. In step S107, the image information selection unit 71 selects the wide-angle image information Dw as the processing image information, and sets (sets) the image information selection flag Fg to 0.

  Here, since the object relative distance Dfw of the front object to be detected is equal to or larger than the reference distance Db, the narrow-angle image information Dn is essentially applicable to the processing image information to be selected according to the object relative distance Dfw. Will do. However, here, in the above-described step S105, it has been detected that a deviation has occurred between the planned traveling direction Dcp of the host vehicle and the narrow-angle central line direction Dcl. Therefore, if the narrow-angle image information Dn is selected as the processing image information, the front object located far from the host vehicle detected by the object relative distance calculation unit 61 is out of the field of view of the narrow-angle camera 4. It becomes difficult to detect by image processing in the image processing unit 72. For this reason, in this step, even when the processing image information to be selected according to the object relative distance Dfw is the narrow-angle image information Dn, the wide-angle image information Dw is selected. When the process of step S107 ends, the process proceeds to step S108.

In step S <b> 108, the image processing unit 72 acquires the set value of the image information selection flag Fg based on the image selection signal from the image information selection unit 71. And a front object is detected using the image information for a process which is the image information which the image information selection part 71 has selected as the image information for a process among the narrow angle image information Dn and the wide angle image information Dw. That is, when the image information selection flag Fg is set to 1, image processing is performed using the narrow angle image information Dn, and a forward object is detected. On the other hand, when the image information selection flag Fg is set to 0, image processing is performed using the wide-angle image information Dw, and a forward object is detected. The image processing in this step can be exemplified by edge detection, for example. An edge is a boundary between a high luminance portion (bright portion) and a low luminance portion (dark portion) in each pixel in the image region. Edge detection is detection of this boundary by image processing.

  When performing the processing in step S108, the image processing unit 72 sets a so-called window around the area where the forward object exists in the image area of the processing image information, and performs edge processing on the inner area of this window. Detection may be performed. The setting of the window is a technique for functioning to demarcate (cut out) the target area for image processing from the entire image area, and since the contents thereof are known techniques, detailed description thereof is omitted. It should be noted that the presence area of the front object in the image area can be obtained based on a signal output from the millimeter wave radar 2. When the process of step S108 ends, the process proceeds to step S109.

  In step S109, the collision determination unit 74 determines whether or not there is a high possibility that the host vehicle will collide with a forward object detected by the image processing unit 72. The collision determination unit 74 includes the lateral position information of the forward object detected by the image processing unit 72 (relative lateral position and size with respect to the longitudinal axis of the host vehicle), the object relative distance calculation unit 61, and the object relative Based on the relative distance and relative speed of the front object calculated by each of the speed calculation units 62 with respect to the host vehicle, it is determined whether or not there is a high possibility that the host vehicle and the front object will collide.

  In this step, when it is determined that there is a low possibility that a front object will collide with the host vehicle, this routine is temporarily ended. On the other hand, if it is determined that there is a high possibility that the front object will collide with the host vehicle, the process proceeds to step S110, and a control signal is transmitted to the seat belt retracting actuator, the pre-crash brake actuator, etc. (not shown). To implement collision damage reduction control. Further, the system ECU 7 sends a warning ON signal to a warning device (not shown) to the driver to notify that there is a high possibility that the host vehicle will collide with a front object (give a warning). When the processing of this step is finished, this routine is once finished.

  As described above, according to the vehicle front monitoring apparatus 1 according to the present embodiment, when the steering of the host vehicle is steered, between the planned traveling direction Dcp of the host vehicle and the narrow angle-of-view centerline direction Dcl. When the deviation occurs, the wide-angle image information Dw is selected as the processing image information even when the processing image information to be selected according to the object relative distance Dfw is the narrow-angle image information Dn. That is, in a situation where there is a deviation between the planned traveling direction Dcp of the host vehicle and the narrow-angle-angle centerline direction Dcl, not only the near-front object but also the far-forward object is displayed as compared to the narrow-angle camera 4. An image is picked up using the wide-angle camera 3 with a large angle, and a front object is detected using the wide-angle image information Dw. Thereby, even in a situation where the steering of the host vehicle is being steered, it is possible to more reliably detect a forward object located far away from the host vehicle. Therefore, it is possible to maintain the continuity and continuity of the monitoring system ahead of the vehicle before and after a deviation occurs between the planned traveling direction Dcp of the host vehicle and the narrow-angle-of-viewline centerline direction Dcl. Therefore, when the pre-crash safety system (PCS) should be operated, the system can be operated more reliably.

  In addition, at the time of detecting a distant forward object, for example, after the avoidance travel of both front road parking ends, the deviation between the planned traveling direction Dcp of the host vehicle and the narrow-angle central line direction Dcl disappears. The processing image information may be switched from the wide-angle image information Dw to the narrow-angle image information Dn. This is because, if the above-mentioned deviation disappears, it is more convenient to use narrow-angle image information Dn that has excellent edge detection accuracy for a distant target. When the steering amount θst is reduced to such an extent that the front object is considered to fall within the field of view of the narrow-angle camera 4, the processing image information is switched from the wide-angle image information Dw to the narrow-angle image information Dn. You may make it do.

  Next, Example 2 will be described. Here, a description will be given of the control contents when a shift between the host vehicle's planned traveling direction Dcp and the narrow view angle center line direction Dcl occurs when the host vehicle travels on a curved road or before entering the curved road. FIG. 6 is a block diagram illustrating a schematic configuration of the vehicle forward monitoring apparatus 1 according to the second embodiment.

  The vehicle front monitoring apparatus 1 according to the present embodiment includes a curvature detection unit 75 that detects the curvature of the travel path on which the host vehicle travels instead of the steering angle sensor 5. The curvature detection unit 75 in this embodiment is a part of the components of the system system ECU 7. The “curvature” is a physical quantity that generally represents the degree or degree of curve or curved surface bending. When such a curve or curved surface is approximated to a circle, the radius of the circle is the “curvature radius”, and the inverse of the curvature radius is the “curvature”. In the present embodiment, the direction deviation detection unit 73 is based on the curvature of the traveling road (road) detected by the curvature detection unit 75, and between the planned traveling direction Dcp of the host vehicle and the narrow-angle-angle centerline direction Dcl. It is characterized by detecting a shift. In addition, the curvature of the travel path in this specification means the reciprocal of the curve radius.

  FIG. 7 is a flowchart showing a control routine in the second embodiment. This control routine is a routine that is repeatedly performed at regular intervals (for example, about 100 ms) in cooperation with the radar ECU 6 and the system ECU 7. In this routine, processes that are the same as those in the control routine described with reference to FIG.

  If an affirmative determination is made in step S102 of this routine, that is, if it is determined that the object relative distance Dfw is greater than or equal to the reference distance Db, the process proceeds to step S201. In step S201, the curvature detection unit 75 calculates the curvature (hereinafter referred to as “road curvature”) γc of the traveling path of the host vehicle. The curvature detection unit 75 performs, for example, image processing based on the current processing image information, and road marking lines that divide both ends of the traveling lane in which the host vehicle is traveling (white lines, yellow lines, In some cases, such as a block arranged or embedded on the road, it is hereinafter referred to as a “white line”), and the travel lane in which the vehicle travels is recognized. Next, the curvature detection unit 75 calculates a line passing through the center (that is, the center of the lane) from the recognized pair of white lines, calculates a radius of the center of the lane (curve radius R), and calculates the road curvature from the curve radius R. γc (= 1 / R) is calculated. The road curvature γc calculated by the curvature detection unit 75 is input to the direction deviation detection unit 73.

  In step S202, the direction deviation detection unit 73 determines whether or not the road curvature γc is equal to or greater than the specified curvature γcb. Here, the larger the road curvature γc, the sharper the curve of the curved road on which the host vehicle travels. The prescribed curvature γcb is that when a front object whose relative distance Dfw to the host vehicle is just at the reference distance Db is to be imaged by the narrow-angle camera 4, the front object is out of the field of view of the narrow-angle camera 4. Is defined as the minimum value of the curvature of the travel path. In this embodiment, the curvature detection unit 75 corresponds to the curvature detection unit in the present invention. In the present embodiment, the direction deviation detection unit 73 corresponds to the direction deviation detection means in the present invention.

  If a negative determination is made in step S202 (γc <γcb), the direction deviation detection unit 73 detects that no deviation has occurred between the planned traveling direction Dcp of the host vehicle and the narrow-angle central line direction Dcl, The process proceeds to step S106. On the other hand, when an affirmative determination is made in step S202 (γc ≧ γcb), the direction deviation detection unit 73 detects that a deviation has occurred between the planned traveling direction Dcp of the host vehicle and the narrow field angle center line direction Dcl. The process proceeds to step S107. Since the processes related to the subsequent steps are already described, the description thereof is omitted.

  As described above, according to the vehicle front monitoring apparatus 1 according to the present embodiment, when traveling on a curved road or before entering the curved road, the traveling direction Dcp of the host vehicle and the narrow-angle central line direction Dcl When a deviation occurs, wide-angle image information Dw is selected as the processing image information even when the processing image information to be selected according to the object relative distance Dfw is the narrow-angle image information Dn. That is, in a situation where there is a deviation between the planned traveling direction Dcp of the host vehicle and the narrow-angle-angle centerline direction Dcl, not only the near-front object but also the far-forward object is displayed as compared to the narrow-angle camera 4. An image is picked up using the wide-angle camera 3 with a large angle, and a front object is detected using the wide-angle image information Dw. As a result, even when traveling on a curved road, or when traveling on the front of a curved road (for example, a straight straight road entering the curved road also applies), a forward object located far from the host vehicle is more reliably detected. Can be detected. Therefore, it is possible to maintain the continuity and continuity of the monitoring system ahead of the vehicle before and after a deviation occurs between the planned traveling direction Dcp of the host vehicle and the narrow-angle-of-viewline centerline direction Dcl. Therefore, when the pre-crash safety system (PCS) should be operated, the system can be operated more reliably.

  Note that the control according to the present embodiment and the control according to the first embodiment may be performed in combination. According to this, it becomes possible to more suitably maintain the continuity and continuity of the monitoring system in front of the vehicle in the vehicle forward monitoring device 1. Further, in this embodiment, the curvature detection unit 75 may obtain the road curvature γc by a method other than the above, and the direction deviation detection unit 73 narrows the planned traveling direction Dcp of the host vehicle based on other methods. A deviation from the angular center line direction Dcl may be detected. For example, the vehicle forward monitoring apparatus 1 may include a navigation system, and the navigation system may acquire the timing at which the host vehicle approaches a curved road. Thereby, it is possible to suitably detect the occurrence of a deviation between the planned traveling direction Dcp of the host vehicle and the narrow-angle-angle centerline direction Dcl.

DESCRIPTION OF SYMBOLS 1 ... Vehicle front monitoring apparatus 2 ... Millimeter wave radar 3 ... Wide angle camera 4 ... Narrow angle camera 5 ... Steering angle sensor 6 ... Radar ECU
7 ... System ECU
61 .. Object relative distance calculation unit 62 .. Object relative speed calculation unit 71.. Image information selection unit 72.. Image processing unit 73 .. Direction deviation detection unit 74 .. Collision determination unit 75.

Claims (3)

An in-vehicle narrow-angle camera that images the front of the vehicle,
A vehicle-mounted wide-angle camera that has a wider angle of view than the narrow-angle camera and images the front of the host vehicle;
Any of narrow-angle image information that is image information generated by the narrow-angle camera and wide-angle image information that is image information generated by the wide-angle camera according to the relative distance between the front object existing ahead of the host vehicle and the host vehicle. Selecting means for selecting either as image information for processing which is image information used for image processing;
Image processing means for performing image processing using the processing image information selected by the selection means and detecting a forward object existing ahead of the host vehicle;
Direction deviation detection means for detecting a deviation of the angle-of-view center line direction of the narrow-angle camera with respect to the traveling direction in which the host vehicle should travel;
A steering angle detector for detecting the steering angle of the steering of the host vehicle;
With
The selection means selects the narrow-angle image information as the processing image information when the relative distance is equal to or greater than a predetermined reference distance,
The direction deviation detection means detects the deviation when a change amount of the steering angle detected by the steering angle detection unit is equal to or larger than a predetermined amount determined according to the reference distance,
The selection means selects the wide-angle image information even when the image information for processing to be selected according to the relative distance is the narrow-angle image information when the deviation is detected by the direction deviation detection means. A vehicle forward monitoring device characterized by that. An in-vehicle narrow-angle camera that images the front of the vehicle,
A vehicle-mounted wide-angle camera that has a wider angle of view than the narrow-angle camera and images the front of the host vehicle;
Any of narrow-angle image information that is image information generated by the narrow-angle camera and wide-angle image information that is image information generated by the wide-angle camera according to the relative distance between the front object existing ahead of the host vehicle and the host vehicle. Selecting means for selecting either as image information for processing which is image information used for image processing;
Image processing means for performing image processing using the processing image information selected by the selection means and detecting a forward object existing ahead of the host vehicle;
Direction deviation detection means for detecting a deviation of the angle-of-view center line direction of the narrow-angle camera with respect to the traveling direction in which the host vehicle should travel
A curvature detection unit for detecting the curvature of the travel path on which the host vehicle travels;
With
The selection means selects the narrow-angle image information as the processing image information when the relative distance is equal to or greater than a predetermined reference distance,
The direction deviation detection means detects the deviation when the curvature detected by the curvature detection unit is equal to or greater than a prescribed curvature determined according to the reference distance,
The selection means selects the wide-angle image information even when the image information for processing to be selected according to the relative distance is the narrow-angle image information when the deviation is detected by the direction deviation detection means. A vehicle forward monitoring device characterized by that. A curvature detection unit for detecting a curvature of a traveling path on which the vehicle travels;
The selection means selects the narrow-angle image information as the processing image information when the relative distance is equal to or greater than a predetermined reference distance,
The directional deviation detecting means, the curvature detected by the curvature detecting section, a vehicle front monitoring according to claim 1, characterized in that for detecting the displacement in the case of less than the prescribed curvature determined according to the reference distance apparatus.

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