JP4890892B2 - Ranging device for vehicles - Google Patents

Description

  The present invention relates to a vehicle distance measuring device that measures the distance to an object existing ahead by scanning an electromagnetic wave such as a laser beam, and in particular, whether the object is a signboard that is above the head of a traveling lane. The present invention relates to an apparatus for determining

  2. Description of the Related Art Conventionally, there is a vehicle distance measuring device that measures whether or not an object is a vehicle and measures the distance to the object by irradiating the front of the vehicle with a laser beam or the like. Using this vehicular distance measuring device, a distance between the preceding vehicle is measured, and a constant inter-vehicle distance following traveling (ACC: Adaptive Cruise Control) is performed to keep the inter-vehicle distance constant. In addition, safety control is performed such that a warning sound is emitted to the driver, the seat belt is tightened, and braking is performed when the inter-vehicle distance is equal to or less than a safe distance.

  In order to perform the control as described above, it is important to accurately detect whether the object is a vehicle and to accurately measure the distance to the object. For this purpose, it is necessary to reliably irradiate the preceding vehicle with laser light or the like. In view of this, an apparatus has been proposed that detects the deviation of the vertical axis from the detection frequency of a signboard existing above the own lane (see Patent Document 1). There has also been proposed an apparatus that detects the deviation of the vertical axis (optical axis) based on the distance immediately before the signboard cannot be recognized (see Patent Document 2). When it is determined by these devices that the vertical axis deviation amount is larger than the predetermined range, the operation of the safety control is canceled. In this way, the distance to the object can be reliably measured.

When it is determined that the vehicle is approaching the preceding vehicle in the first detection area and the preceding vehicle is no longer detected, the first detection area is switched to the second detection area including the area above the first detection area. There has been proposed a preceding vehicle recognition device that sets the maximum detection distance of the second detection area based on the distance to the preceding vehicle before switching (see Patent Document 3). According to this, the preceding vehicle is not lost (lost), and an effect of reducing erroneous detection of a signboard or the like above the own lane can be obtained.
JP 2002-202360 A JP 2003-43147 A JP 2000-315299 A

  However, the conventional devices of Patent Document 1 and Patent Document 2 do not disclose a method for accurately detecting a signboard existing above the own lane, for example, a vehicle in which a reflector is arranged at a high position in the upward direction. There was a possibility of misdetecting the signboard above the own lane. If a signboard above the own lane is erroneously detected as a stop (obstacle) existing on the ground, even if the signboard is not actually in contact, safety control may be activated and unnecessary braking or the like may occur.

  In the device of Patent Document 3, the detection area is shifted upward when a preceding vehicle having a reflector installed at a high position is lost, so that the preceding vehicle is not lost, and the maximum detection distance after the shift Is set based on the distance to the preceding vehicle before switching, so that erroneous detection of a signboard or the like can be reduced. However, in the first place, when a signboard was erroneously detected from a distance, there was a problem of continuing to detect it incorrectly. 12-14 is a figure for demonstrating that such a situation generate | occur | produces.

  FIG. 12 shows a state in which a laser beam 3 is irradiated forward from a laser radar 2 provided at the front of the host vehicle 1. FIG. 2A shows a state in which the laser beam 3 is not reflected by the reflector 6 of the preceding vehicle (truck) 5 but is diffusely diffusely reflected by the rear lower part (and the road surface 4) of the loading platform. In this case, the preceding vehicle is lost. In the apparatus of Patent Document 3, when the preceding vehicle is lost as described above, the detection area is shifted upward as shown in FIG. Thereby, the preceding vehicle recognition accuracy is improved.

  FIG. 13 shows a state where the signboard 7 is present in front of the automobile. As shown in FIG. 4A, a signboard 7 exists above the track 5. In FIG. 5A, the laser beam 3 is reflected by the track 5 and the laser beam 3 is blocked by the track 5, so that the sign 7 is not irradiated with the laser beam 3. Here, when the preceding vehicle changes lanes and no longer exists in front of the own vehicle (when it no longer exists in front of the own vehicle instead of lost), as shown in FIG. Is shifted upward. At this time, the maximum detection distance is determined based on the distance at the time when the preceding vehicle is lost. Therefore, although the laser beam 3 is reflected by the signboard 7, since it exceeds the maximum detection distance, it is not erroneously detected.

  However, as shown in FIG. 14A, when the signboard 7 is erroneously detected as a preceding vehicle or the like at a distance, if this is lost, the detection area is shifted upward as shown in FIG. 14B. For this reason, since the signboard 7 is present at a position closer than the maximum detection distance, erroneous detection continues.

  Furthermore, as shown in FIG. 3C, in rainy weather, there is a problem that the laser light is diffused by the influence of raindrops adhering to the automobile, and the laser light is irradiated to the upper side which is not normally irradiated. It was. In this case, even at a short distance of the host vehicle, the upper signboard is irradiated with the laser light, and the possibility of erroneous detection is high.

  The present invention provides a vehicle ranging device that reliably recognizes a preceding vehicle with a reflector at a high position and prevents erroneous detection of an overhead signboard that does not actually become an obstacle regardless of the weather. Objective.

Further, the vehicle distance measuring device of the present invention scans electromagnetic waves in the horizontal direction and the vertical direction, detects a forward object based on the received reflected wave, and measures the distance and direction of the object. And a width determination means for estimating the width of the detected object from the detected object distance and the angular range of the detection direction, and the object detected by the radar scan unit is a stationary object, and the distance value of the object Is an object having a width equal to or greater than a first predetermined value and the width of the object is equal to or greater than a predetermined width, or a stationary object among objects detected in a top scan in the vertical direction or a scan in the vicinity thereof, Recording means for recording an object having a distance value of the object equal to or greater than a first predetermined value as a signboard candidate object together with the distance value of the object, own vehicle speed detecting means for detecting the speed of the own vehicle, and the recording means Recorded in The distance value signboard candidate object being, said updating means for updating the estimated value based on the speed of the vehicle, out of the objects the radar scan unit detects a stationary object, the distance value of the object When the second condition is less than a second predetermined value that is smaller than the first predetermined value and the distance value of the object is substantially the same as the estimated value, the object is determined as an overhead signboard It is characterized by doing.
In the vehicle distance measuring device according to the present invention, further, the recording means may detect the signboard candidate object when the object is detected near the center of the lane even if the width of the object is less than a predetermined width. It is characterized by recording.

  In the present invention, the control circuit is a stationary object with respect to the detected object, the distance value is not less than a predetermined value (for example, 70 m), and as a result of referring to the width value recorded in the memory, a predetermined width (for example, 3 m) is obtained. ) If there is a value greater than or equal to the value, the object is registered in the signboard candidate list. Further, when detected in the upper scan, the object is registered in the signboard candidate list even if it is less than a predetermined width (for example, 3 m). Further, the control circuit estimates and updates the existence position of the registered object from the vehicle speed of the own vehicle. When the object is detected, the control circuit is a stationary object, the distance value is less than a predetermined value (for example, 50 m), and the distance value of the object is substantially the same as the estimated value of the signboard candidate list (for example, in one frame time) If it is within the difference of the distance value of the moving own vehicle), the object is determined as an overhead signboard.

  In the vehicle range finder according to the present invention, the sign determining unit may detect the object that satisfies the second condition by the lowest scan in the vertical direction or a scan in the vicinity thereof. The object is not determined as an overhead signboard.

  In this invention, when the control circuit detects an object, it is a stationary object, the distance value is less than a predetermined value (for example, 50 m), and the distance value of the object is substantially the same as the estimated value of the signboard candidate list. However, when it is detected in the lower scan, the object is not determined as an overhead signboard.

  In addition, the vehicle distance measuring device of the present invention further includes road shape estimation means for estimating a road shape ahead of the host vehicle, and the signboard determination means includes the second of the objects detected by the radar scan unit. In addition to satisfying the above condition, when the road shape estimation means estimates that the road shape ahead of the host vehicle is a straight line shape or a curve shape with a predetermined radius or more, the object is determined as an overhead signboard. It is characterized by.

  In this invention, the road shape ahead is estimated. What is necessary is just to estimate the road shape ahead, for example from a yaw rate, the steering angle of a steering wheel, etc. Whether the vehicle is traveling on a straight road or a curve is detected. If the vehicle is traveling on a curve, the road radius is calculated. In addition to the above-described conditions, the control circuit determines that the object is an overhead signboard when it is determined that the vehicle is traveling on a straight road or traveling on a curve having a predetermined radius (for example, 300 m) or more. .

  According to the present invention, when the object is a stationary object, the distance value is equal to or greater than a predetermined value (for example, 70 m), and the width is equal to or greater than a predetermined width (for example, 3 m), the object is determined to be an overhead signboard. It is possible to reliably recognize a preceding vehicle at a high position and to prevent erroneous detection of a signboard. In addition, when an object is detected, it is recorded as a signboard candidate, and when determining whether or not it is a signboard at a nearby distance, an estimated distance value estimated from the distance value of the object and the distance value at the time of signboard candidate recording Are compared, and it is determined that the sign is an overhead signboard. Therefore, even if the beam is diffused as in rainy weather, erroneous detection can be prevented.

FIG. 1 is a block diagram of a laser radar device (vehicle ranging device) according to an embodiment of the present invention.
An LD (Laser Diode) drive circuit 10 controls light emission of the LD 12 based on the drive signal generated by the control circuit 11. The scanner 13 scans the laser beam generated by the LD 12 within a predetermined scan range based on the control of the control circuit 11. The laser beam emitted from the scanner 13 is emitted in the traveling direction (forward) of the host vehicle 1 through the light projecting lens. The vertical scanning position detection device 14 and the horizontal scanning position detection device 15 detect the scanning (scanning) position of the laser beam in the scanner 13 in the horizontal direction and the vertical direction, respectively, and output them to the control circuit 11.

  The reflected light returned from the laser beam emitted from the LD 12 after being reflected by a front object (for example, a vehicle or road surface) as a detection target is collected by a light receiving lens and received by a PD (Photo Diode) 16. A signal corresponding to the received light level is output to the light receiving circuit 17. The light receiving circuit 17 digitizes the signal level of the input reflected light and outputs it to the control circuit 11. The control circuit 11 stores the input numerical value (light reception level) in the memory 18 corresponding to the scanning position input from the vertical scanning position detection device 14 and the horizontal scanning position detection device 15. The memory 18 also has an overhead sign determination flag for determining that the detected object is an overhead sign when it is recognized that the detected object is an upward sign (hereinafter referred to as an overhead sign). Is assigned. Also, a program that defines numerical values such as the distance and width of each object used for recognizing that it is an overhead signboard, and a procedure for performing recognition processing is recorded.

  A vehicle speed sensor 19 and a gyro 20 are connected to the control circuit 11. The vehicle speed sensor 19 detects the vehicle speed of the host vehicle, and the gyro 20 detects the yaw rate of the host vehicle (the turning speed when turning in the horizontal direction). Used to do.

  The control circuit 11 corrects the optical axis (vertical center position of the scan range) based on the light reception level stored in the memory 18 and also the time from when the laser light is emitted until the reflected light is received. Based on the above, the distance between the object and the vehicle is measured. Further, the control circuit 11 can obtain the moving speed and moving direction (moving vector) of the object by repeating the detection of the distance to the object a plurality of times continuously, and the detected object having the same moving vector can be obtained. By determining as the same object, the size (width) of the object can be calculated. The control circuit 11 determines whether the detected object is an overhead signboard and whether it is a preceding vehicle from the information of these objects. The preceding vehicle means a vehicle (one vehicle) immediately before traveling in front of the lane in which the host vehicle is traveling.

FIG. 2 shows a configuration of a portion that supports the light projecting lens and the light receiving lens of the scanner 13.
A control signal from the control circuit 11 is input to the drive circuit 30. The drive circuit 30 supplies a drive current to the horizontal direction drive coil 31 and the vertical direction drive coil 32 based on the input control signal. The horizontal driving coil 31 and the vertical coil 32 move a support member (not shown) that integrally supports the light projecting lens 35 and the light receiving lens 36 in the horizontal direction or the vertical direction, respectively. The support member is supported by a horizontal plate spring 33 and a vertical plate spring 34 so as to be movable in the horizontal direction or the vertical direction, respectively. Therefore, the support member (the light projecting lens 35 and the light receiving lens 36) moves to a horizontal position where the force generated in the horizontal driving coil 31 by the driving current and the reaction force generated in the horizontal leaf spring 33 are balanced. In addition to being stationary, it moves to a position where the force generated in the vertical driving coil 32 and the reaction force and gravity generated in the vertical leaf spring 34 are balanced, and is stationary. The position of each lens is detected by a sensor (not shown) and the sensor output is input to the drive circuit 30 to constitute a servo mechanism.

  In this way, the light projecting lens 35 and the light receiving lens 36 can move to predetermined positions in both the horizontal direction and the vertical direction.

  FIG. 3 shows optical paths of the light projecting lens 35 and the light receiving lens 36 driven by the scanner 13. The light projecting lens 35 is provided on the front surface of the LD 12, and the light receiving lens 36 is provided on the front surface of the PD 16.

  The laser light emitted from the LD 12 is polarized in the center direction of the light projecting lens 35. When the position of the projection lens 35 is at the center, the laser beam is emitted to the front along the optical path as indicated by the solid line in FIG. The emitted laser light is reflected by an object (for example, a vehicle) ahead, enters the light receiving lens 36 through an optical path as indicated by a solid line in FIG. 3, and is received by the PD 16.

  Further, when the projection lens 35 is moved upward in the figure by the scanner 13, the laser light is emitted upward in the figure along an optical path as indicated by a dotted line in FIG. The emitted laser light is reflected by an object in the upward direction in the drawing, enters the light receiving lens 36 through an optical path as indicated by a dotted line in FIG. 3, and is received by the PD 16.

  In this manner, the scanner 13 scans the laser light in the horizontal direction by moving the light projecting lens 35 and the light receiving lens 36 integrally to a predetermined position in the horizontal direction. Similarly, the scanner 13 scans the laser light in the vertical direction by moving the light projecting lens 35 and the light receiving lens 36 integrally in the vertical direction.

FIG. 4 is a diagram for explaining scanning in the horizontal direction and the vertical direction.
In this apparatus, the vertical position of the scan in one frame of the measurement process is set in three stages, upper, middle, and lower, which are scan (upper), scan (middle), and scan (lower), respectively. Each scan time is set to, for example, 50 msec in this apparatus. The scanning range of each scan (laser beam vertical spread angle range) is partially overlapped so that there is no leakage in the scanning range. For example, if the scan (middle) is substantially horizontal to the ground, the scan (up) is twice above the scan (middle), and the scan (down) is twice below the scan (middle). Set to

  These three scans constitute one frame, and the measurement data processing executed in each frame includes overhead signboard determination processing and preceding vehicle determination processing. In the overhead signboard determination process, it is determined whether or not the object is an overhead signboard. If the object is recognized as an overhead signboard, an overhead signboard determination flag is set for the object, and thereafter, the object is confirmed and recognized as an overhead signboard. To do. Further, in the preceding vehicle determination process, it is determined which of the preceding vehicles is an object that has not been determined to be a signboard. When the type of object (overhead signboard, preceding vehicle, etc.) is recognized, this information is transmitted to a vehicle control device (not shown) connected to the subsequent stage together with information on the distance and direction of the object. In the vehicle control device, safety control such as ACC that keeps the distance between the preceding vehicle and the preceding vehicle constant, or a warning sound to the driver, tightening the seat belt, or braking when the distance between the vehicles is below a safe distance is performed. Is called.

  In this example, the vertical direction of each scan is set to the upper, middle, and lower three stages. However, one frame is constituted by the upper, middle, and two lower and middle stages. Also good. In the above example, the case of scanning in the same direction (scanning in the left direction) has been described, but scanning in the opposite direction may be included. For example, left scan (middle) → right scan (down) → left scan (middle) → right scan (up) → left scan (middle) → right scan (bottom) →... Thus, the horizontal and vertical scans (two-dimensional scans) may be continuously performed.

Hereinafter, specific procedures of measurement data will be described in detail with reference to FIGS.
FIG. 5 is a diagram showing an entire procedure of measurement data processing.
When the measurement data obtained in an arbitrary frame is taken into the memory 18, the control circuit 11 first performs an estimation process of the front road shape based on the yaw rate of the own vehicle detected by the gyro 20 in ST1. That is, it detects whether the vehicle is traveling on a straight road or a curve, and if the vehicle is traveling on a curve, the road radius is calculated. Note that the shape of the road ahead is not limited to estimation based on the yaw rate. For example, it can be estimated from the steering angle of the steering wheel. It can also be estimated by a combination of GPS and navigation, and also by a combination of a camera that captures the front and an image processing device that detects a white line displayed on the road from the captured image content. Can be estimated. When estimating based on the yaw rate or the steering angle of the steering wheel, the front road shape is estimated when the host vehicle is traveling. When estimating using GPS and navigation, or a camera and an image processing device, the road shape ahead can be estimated more accurately.

Next, the control circuit 11 turns off the overhead signboard determination flag in ST2, and performs so-called initialization processing.
In ST3, the control circuit 11 performs data update processing for the registered signboard candidate list. The signboard candidate list is obtained by recording the distance of each detected object in the memory 18 for an object that has the possibility of an overhead signboard. FIG. 6 shows an example of the signboard candidate list. As shown in the figure, the signboard candidate list is composed of three items of a list element number, a registration distance, and a downward detection flag, and an object determined to be an overhead signboard (described in detail in the process of ST5). ) For each signboard candidate object, and the distance at that time is described as the registered distance. The down direction detection flag will be described later.

  Next, in ST4 to ST8, the control circuit 11 performs a determination process as to whether or not each detected object is an overhead signboard. When the process for all the detected objects is completed, the process proceeds to the preceding vehicle determination process of ST9, and the process for the measurement data obtained from the frame is completed.

In the overhead signboard determination process, in ST4, it is determined whether or not the detected object is a stationary object. To determine whether the object is a stationary object, calculate the distance difference from the same object that was detected in the previous frame, obtain the relative speed with the detected object from the elapsed time from the previous frame, If it is approaching at the same speed as, it is judged as a stopped object.
In ST5, a new signboard candidate list registration process is performed. As described above, the signboard candidate list is obtained by recording the distance of an object that has the possibility of an overhead signboard among the detected objects. If the object is already registered, this process is not performed. Details will be described later with reference to FIG.

In ST6, an overhead signboard determination (distant) process is performed. In this process, for an object whose distance from the vehicle is a predetermined distance (for example, 70 m) or more, it is determined whether or not the object is an overhead signboard.
In ST7, an overhead signboard determination (neighboring) process is performed. In this process, for an object whose distance from the vehicle is closer than a predetermined distance (for example, 50 m), it is determined whether or not the object is an overhead signboard.
In ST8, it is determined whether or not the processing of ST4 to ST7 has been performed for all detected objects.

Hereinafter, each process (ST3, ST5, ST6, ST7, and ST9) will be described in detail.
FIG. 7 shows the procedure of the registered signboard candidate list data update process. This process is a process for updating previously registered contents described in the signboard candidate list, and is performed regardless of whether or not an object is detected. That is, this process is performed even when a new object is not detected or the object is lost.
First, the value of the registration distance described in the signboard candidate list is updated (s11). This updated value is a value calculated by the equation (distance value after update) = (distance value before update) − (distance traveled by the vehicle during one frame). That is, the current position of the object (signboard candidate object) is estimated by subtracting the distance traveled by the vehicle from the distance value one frame before. The distance traveled by the host vehicle is calculated from the vehicle speed detected by the vehicle speed sensor 19.

  Next, it is determined whether or not the updated distance value is smaller than 0 (s12). If the distance value is smaller than 0, it is determined that the object has already passed the own vehicle and is located behind, and is deleted from the signboard candidate list (s13). If the updated distance value is 0 or more, it is determined whether or not the updated distance value is close (substantially coincides) with the downward detection distance value of the detected object in the area corresponding to the host vehicle lane (s14). ). That is, it is determined whether or not the difference between the updated distance value and the downward detection distance value in the vicinity of the lane center is equal to or less than a predetermined value (for example, own vehicle speed × one frame time). Here, the vicinity of the lane center indicates a direction corresponding to the own vehicle traveling lane estimated from the shape of the front road calculated in ST1. Further, the downward detection distance value near the lane center indicates the distance value of the object detected near the lane center in the scan (lower) shown in FIG. This determination is made for all detected objects. Note that the distance value of the object detected in the scan (lower) may be compared with the updated distance value even if it is not near the center of the lane.

  When the difference between the updated distance value and the downward detection distance value of each object in the vicinity of the lane center is larger than a predetermined value, that is, in the registered distance value (updated distance value) of each registered signboard candidate object, If no object is detected near the center in (lower), the downward detection flag of the signboard candidate object is turned off (s15). If the difference between the updated distance value and the downward detection distance value of each object near the lane center is equal to or smaller than a predetermined value, the downward direction detection flag is turned on (s16). Although details will be described later, if the down direction detection flag is off during the signboard determination process, the object is determined to be an overhead signboard, and if the down direction detection flag is on, the obstacle that hinders the traveling of the vehicle on the ground It is determined as an object (or preceding vehicle). In addition, detection objects other than those in the vicinity of the lane center are extremely unlikely to interfere with the traveling of the host vehicle, and therefore each object in the vicinity of the lane center is determined.

  It is determined whether or not the processes of s11 to s16 have been performed for all registered objects (s17), the procedure of the registered signboard candidate list data update process of ST3 is completed, and the process returns to the measurement data process of FIG.

  Next, the signboard candidate list new registration processing procedure of ST5 will be described with reference to FIG. This procedure is executed when it is determined that each detected object is a stationary object in ST4. First, in s21, the control circuit 11 determines whether or not the distance value of the detected object is 70 m or more. If it is less than 70 m, it is not newly registered in the signboard candidate list, and the process returns to the measurement data processing of FIG. Here, in the process of s21, 70 m is described as a determination criterion, but this is an example and does not limit the present invention. The numerical value may be adjusted according to actual use conditions.

  If it is determined in s21 that the distance value of the object is 70 m or more, the control circuit 11 reads the memory 18 and determines whether or not the maximum width of the object has been detected as 3 m or more in the past detection (s22). If a width of 3 m or more has been detected in the past, this object may be an overhead signboard, so it is registered in the signboard candidate list and its distance value is registered (s23). However, if the same distance value is already registered in the signboard candidate list, it is not added and registered. Note that 3m is an example of the determination value of s22, and the determination value is not limited thereto.

  In s22, if the maximum width of the object is not detected as 3 m or more at the time of past detection, it is determined whether or not the object is detected near the center of the lane (s24). Further, it is determined whether or not the object has been detected in the scan near the center of the lane (upper side) (s25). If it is not detected in the vicinity of the lane center or detected in the scan (upper) near the lane center, it is not registered in the signboard candidate list, and the process returns to the measurement data processing of FIG. If it is detected in the vicinity of the lane center and is detected by scanning (up), it is registered in the signboard candidate list that there is a possibility of an overhead signboard (s23). In addition, without performing the process of s24, if it is detected by scanning (up), there is a possibility of an overhead signboard, and it may be registered in the signboard candidate list. When it rains, the beam is diffused and the detection accuracy is lowered, so that it may be detected with a width narrower than the actual object width. Therefore, even if the width of the object is less than 3 m, if it is detected by scanning (up), it is registered in the signboard candidate list as having the possibility of an overhead signboard.

  In addition, since an object detected near the center of the lane is likely to be present on the traveling lane of the own vehicle, the influence on the ACC and safety control performed by the subsequent vehicle control device is large. If an overhead signboard near the lane center is misrecognized as a preceding vehicle, unnecessary safety control may be performed. Therefore, even if the width of the object is less than 3 m, it is desirable to register the object detected in the vicinity of the lane center (and the object detected on the scan) in the signboard candidate list. Of course, it is desirable to perform signboard determination in the entire front area other than the center of the lane, but the processing burden can be reduced by registering in the signboard candidate list only in the vicinity of the particularly important lane center.

  When the above process is completed, the process returns to the measurement data process of FIG.

  Next, the procedure of the overhead signboard determination (distant) process in ST6 will be described with reference to FIG. First, the control circuit 11 determines whether or not the distance value of the object detected in s31 is 70 m or more. If the distance value of the object is not 70 m or more, the process returns to the measurement data processing of FIG. If the distance value of the object is 70 m or more, the control circuit 11 reads the memory 18 and determines whether or not the maximum width of the object has been detected as 3 m or more at the time of past detection (s32). If a width of 3 m or more has been detected in the past, it is determined to be an overhead signboard and an overhead signboard determination flag is assigned to the object (s33). Thereafter, this object is determined to be an overhead sign and is not erroneously detected as a preceding vehicle. If a width of 3 m or more has not been detected in the past, it is further determined whether or not the object has been detected in the scan (up) (s34). If a width of 3 m or more has not been detected in the past and has not been detected in the scan (upper), it is determined that this is not an overhead signboard in the overhead signboard determination (far) process, and the process returns to the measurement data process of FIG. To do. If it is detected in the scan (up), it is determined that it is an overhead signboard, and an overhead signboard determination flag is assigned to the object (s33). Note that the process of s34 is not essential, and if the width of the object is less than 3 m, it may be determined that it is not an overhead signboard. As described above, since the detection accuracy decreases in the rain, it is desirable to determine that the object is a sign if it is detected by scanning (up) even if the width of the object is less than 3 m. Note that the determination values of s31 and s32 are only examples, and are not limited thereto.

  Next, the procedure of the overhead signboard determination (neighboring) process in ST7 will be described with reference to FIG. First, the control circuit 11 determines whether or not the detected distance value of the object is less than 50 m in s41. If the distance value of the object is 50 m or more, the process returns to the measurement data processing of FIG. 5 without determining the vicinity. This distance value is also an example and is not limited. If the distance value of the object is less than 50 m, the control circuit 11 determines whether or not the object is detected near the center of the lane (s42). If not detected in the vicinity of the lane center, the process returns to the measurement data processing of FIG. If it is detected near the center of the lane, it is determined whether the vehicle is traveling straight or traveling on a curve that is gentler than the road radius of 300 m (s43). If the vehicle is traveling on a curve that is steeper than the road radius of 300 m, the process returns to the measurement data processing of FIG. In this determination, the estimation of the shape of the front road obtained in ST1 is used. The reference value of the road radius is 300 m as an example, and is not limited to this.

  When it is determined that the vehicle is traveling straight or traveling on a curve that is gentler than the road radius of 300 m, the control circuit 11 reads the signboard candidate list registered in the memory 18 and has a registered distance value close to the distance value of the object. It is determined whether or not a signboard candidate object exists (s44). This determination is made based on whether or not there is a signboard candidate object in which the difference between the distance value of the object and the registered distance value described in the signboard candidate list is equal to or less than the own vehicle movement distance value for one frame, for example. Is called. If there is no corresponding signboard candidate object, the process returns to the measurement data processing of FIG.

  If there is a corresponding signboard candidate object, it is further determined whether or not the downward direction detection flag is turned off for the signboard candidate object (s45). If the downward direction detection flag is on, there is a possibility that the object is present on the ground, so that the process returns to the measurement data processing of FIG. 5 without determining that it is an overhead signboard. If the downward direction detection flag is off, it is determined that the sign is an overhead sign, and an overhead sign determination flag is assigned to the object (s46). Thereafter, this object is determined to be an overhead sign and is not erroneously detected as a preceding vehicle or an obstacle.

  The above processes of ST4 to ST7 are repeated for all detected objects (ST8 in FIG. 5), and the overhead signboard determination process is performed for all objects. If it is determined in ST8 that all objects have been processed, the preceding vehicle determination process in ST9 is performed. The preceding vehicle determination process of ST9 is also performed for each detected object. FIG. 11 is a flowchart illustrating the procedure of the preceding vehicle determination process. First, the control circuit 11 determines whether or not an overhead signboard determination flag is assigned to the object (s51). If the overhead signboard determination flag is not assigned, it is further determined whether or not the object exists within the estimated road shape, that is, within the travel line of the own vehicle (s52). This determination is made based on whether or not the object is detected in the vicinity of the lane center described above.

  If it is determined that the vehicle exists in the travel line of the host vehicle, the object is added to the preceding vehicle candidate list (s53). Similar to the overhead signboard candidate list, the preceding vehicle candidate list describes the distance value of each object. The control circuit 11 determines whether or not the processing of s51 to s53 has been performed for all detected objects (s54). If it is determined in s51 that the overhead sign determination flag is on, or if it is determined in s52 that it is not in the own vehicle travel lane, the preceding vehicle list is not registered and the determination in s54 is performed. If processing has not been performed for all objects, the processing is repeated from s51. If it is determined that processing has been performed for all the objects, the object at the shortest distance in the preceding vehicle candidate list is determined as the preceding vehicle (s55), and the process returns to the measurement data processing of FIG.

  In ST9, only the preceding vehicle is determined. However, the present invention is not limited to this, and it may be further determined whether or not the object is an obstacle existing on the road.

  As described above, when the distance value of an object is not less than a predetermined value (for example, 70 m) and not less than a predetermined width (for example, 3 m), it is determined that the object is an overhead signboard. It is possible to reliably recognize the preceding vehicle in the vehicle and to prevent erroneous detection of the signboard. Furthermore, a signboard candidate list is created when an object is detected, and the distance value of the object is compared with the distance value estimated from the signboard candidate list when determining whether or not the object is a signboard at a nearby distance. Since it is determined that the signboard is an overhead signboard when it is approximately the same, it is possible to prevent the signboard from being erroneously detected even if the beam diffuses as in rainy weather.

  Although the present embodiment has been described with reference to a laser radar device, the present invention can also be applied to other distance measuring devices (for example, a millimeter wave radar).

1 is a block diagram of a laser radar device (vehicle ranging device) according to an embodiment of the present invention. The figure which shows the structure of the part which supports the light projection lens and light reception lens of a scanner. The figure which shows the optical path of the light projection lens and light reception lens which were driven by the scanner Diagram explaining vertical scanning Flow chart showing specific procedure of measurement data processing Figure showing signboard candidate list The flowchart which shows the concrete procedure of registered signboard candidate list data update processing The flowchart which shows the specific procedure of signboard candidate list new registration processing The flowchart which shows the concrete procedure of overhead signboard judgment (far) processing The flowchart which shows the concrete procedure of overhead signboard judgment (neighborhood) processing The flowchart which shows the concrete procedure of preceding vehicle judgment processing The figure which showed a mode that a laser was irradiated ahead The figure which shows a situation when a signboard exists in front of the car A figure showing how a signboard is falsely detected

Claims (4)

A radar scanning unit that scans electromagnetic waves in a horizontal direction and a vertical direction, detects a front object based on the received reflected wave, and measures the distance and direction of the object;
Width determination means for estimating the width of the object from the distance of the detected object and the angular range of the direction of detection;
Among the objects detected by the radar scanning unit, the object is a stationary object, the object whose distance value is equal to or larger than a first predetermined value and the width of the object is equal to or larger than a predetermined width, or the highest in the vertical direction. Of the detected objects in the scan or the scan in the vicinity thereof, an object having a distance value of the object equal to or greater than the first predetermined value is recorded as a signboard candidate object together with the distance value of the object. Recording means;
Own vehicle speed detecting means for detecting the speed of the own vehicle;
Updating means for updating the distance value of the signboard candidate object recorded in the recording means to an estimated value based on the speed of the host vehicle;
Among the objects detected by the radar scan unit, the object is a stationary object, the distance value of the object is less than a second predetermined value smaller than the first predetermined value , and the distance value of the object is the estimated value Ranging device for determining the object as an overhead signboard when a second condition that is substantially the same as the above is satisfied.   The vehicle according to claim 1, wherein the recording unit records the signboard candidate object if the object is detected near the center of the lane even if the width of the object is less than a predetermined width. Distance measuring device. The signboard determining means, said second condition of the object filled, if it is detected by the scan of the lowermost scan or near the vertical direction, according to claim 1 or claim which does not determine the said object as an overhead signboard Item 3. The vehicle distance measuring device according to Item 2 . Provided with a road shape estimating means for estimating the road shape ahead of the host vehicle,
In addition to the case where the second condition is satisfied among the objects detected by the radar scanning unit, the sign determining unit is configured such that the road shape estimation unit sets the road shape ahead of the vehicle to a straight line or a predetermined radius or more. The rangefinder for a vehicle according to any one of claims 1 to 3 , wherein the object is determined as an overhead signboard when it is estimated that the object has a curved shape.

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