JP2011112416A - Vehicle circumference monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle circumference monitoring device capable of improving the detection accuracy of an obstacle present in the vehicle circumference regardless of the road conditions by removing a reflected wave by the road surface from a received reflected wave. <P>SOLUTION: The vehicle circumference monitoring device includes a road surface determination part 3 for determining the road surface condition based on an image of the road surface around the vehicle taken by an on-vehicle camera 2, a threshold value pattern determination part 6 for determining the threshold pattern based on the road surface condition, and an obstacle detection part 4 for detecting the presence or absence of the obstacle based on the signal after removing the reflected wave by the road surface from the received reflected wave using the determined threshold value pattern. Thereby, the appropriate threshold pattern is determined in accordance with the road surface condition and regardless of the road surface conditions, the reflected wave by the road surface can be removed from the received reflected wave, and the detection accuracy of the obstruction present in the vehicle circumference can be improved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle periphery monitoring device, and more particularly, to a vehicle periphery monitoring device that receives a reflected wave of a transmission wave transmitted from an ultrasonic sonar attached to the vehicle and detects an obstacle existing around the vehicle. It is an invention.

  Conventionally, there has been known a vehicle periphery monitoring device that attaches an ultrasonic sonar to a bumper position or the like at the front of the vehicle and receives an reflected wave of a transmission wave transmitted from the ultrasonic sonar to detect an obstacle existing around the vehicle. (For example, Patent Document 1).

JP 2008-096108 A

  However, according to the vehicle periphery monitoring device described above, since the transmission wave transmitted from the ultrasonic sonar is a spherical transmission wave (sound wave), even if the transmission wave is transmitted in the horizontal direction, In this case, a reflected wave (noise) from the road surface is included.

  In addition, for example, when the vehicle is traveling on a road surface with a large degree of unevenness such as a gravel road, the reflected wave reflected intensity by the road surface is higher than when traveling on a road surface with a small degree of unevenness. There is a tendency to grow.

  Therefore, it is required to accurately detect only the reflected wave due to the obstacle to be detected by removing noise from the received reflected wave.

  However, since the intensity of the noise varies depending on the road surface condition of the road surface on which the vehicle is traveling, the reflected wave from the road surface and the reflected wave from the obstacle can be obtained by setting a certain threshold for the received reflected wave and removing the noise. Cannot be distinguished sufficiently, and there is a problem that an obstacle is erroneously detected.

  The present invention has been made in view of the above circumstances, and a vehicle capable of improving the detection accuracy of an obstacle existing around the vehicle by removing the reflected wave from the road surface from the received reflected wave regardless of the road surface state. An object of the present invention is to provide a peripheral monitoring device.

  The vehicle periphery monitoring device according to the present invention determines a road surface state based on an image captured by an in-vehicle camera, and further determines a threshold pattern for removing a reflected wave from the road surface from the received reflected wave based on the determined road surface state. By doing so, the reflected wave by the road surface can be removed regardless of the road surface state, and the detection accuracy of the obstacle existing around the vehicle is improved.

  That is, a vehicle periphery monitoring device according to the present invention is based on an ultrasonic sonar attached to a vehicle, an in-vehicle camera that is provided in the vehicle and images a road surface around the vehicle, and a captured image captured by the in-vehicle camera. A road surface state determination unit that determines a road surface state, and an obstacle detection unit that receives a reflected wave of a transmission wave transmitted from the ultrasonic sonar and detects an obstacle existing around the vehicle, and the obstacle The object detection unit includes a threshold pattern determination unit that determines a threshold pattern for removing the reflected wave from the road surface from the received reflected wave based on the road surface state determined by the road surface state determination unit, and the threshold pattern determination The presence or absence of the obstacle is detected based on the signal after removing the reflected wave from the road surface from the received reflected wave using the threshold pattern determined by the unit. The features.

  According to the vehicle periphery monitoring device according to the present invention configured as described above, the road surface state determination unit determines the road surface state based on the captured image of the road surface around the vehicle captured by the in-vehicle camera, and based on the road surface state. The threshold pattern determining unit determines the threshold pattern. And an obstacle detection part detects the presence or absence of an obstacle based on the signal after removing the reflected wave by a road surface from the received reflected wave using the determined threshold value pattern.

  For this reason, it is possible to improve the detection accuracy of obstacles existing around the vehicle regardless of the road surface condition.

  Also, the obstacle detection unit uses the determined threshold pattern to detect the presence of an obstacle based on the signal after removing the reflected wave from the road surface from the received reflected wave. It is not necessary to apply special measures to the ultrasonic sonar to avoid receiving reflected waves from the road surface, such as installing it upwards, and the same distance characteristics as normal ultrasonic sonar can be maintained. it can.

  Furthermore, in the vehicle periphery monitoring device according to the present invention, the threshold pattern determination unit includes a threshold pattern storage unit that stores in advance a plurality of different threshold patterns that are associated with a road surface state. It is preferable that one threshold pattern is determined from the plurality of threshold patterns stored in the threshold pattern storage unit based on the determined road surface state.

  According to the vehicle periphery monitoring device according to the present invention configured as described above, the threshold pattern determination unit does not need to newly create a threshold pattern, and requires a lot of calculation processing to create the threshold pattern. Therefore, the threshold pattern can be determined particularly in a short time.

  Further, in the vehicle periphery monitoring device according to the present invention, the threshold pattern determination unit is configured to perform a process from the transmission of the transmission wave by the ultrasonic sonar until the obstacle detection unit starts receiving the reflected wave from the road surface. A first reflection time, and a second reflection time from the transmission of the transmission wave by the ultrasonic sonar until the obstacle detection unit receives the reflected wave having the highest reflection intensity among the reflected waves from the road surface; In the threshold pattern, a reflection time storage unit that stores in advance a third reflection time from the transmission of the transmission wave by the ultrasonic sonar until the obstacle detection unit finishes receiving the reflected wave from the road surface, The first reflection intensity corresponding to the first reflection time, the second reflection intensity corresponding to the second reflection time, and the third reflection intensity corresponding to the third reflection time are stored in advance. The first reflection intensity and the third reflection intensity are constant values regardless of the road surface state, and the second reflection intensity is a variable associated with the road surface state. The threshold pattern determination unit determines the two reflection intensities based on the road surface state determined by the road surface state determination unit, and the second reflection intensity and the third reflection determined as the first reflection intensity. The threshold pattern may be determined based on the intensity.

  According to the vehicle periphery monitoring device according to the present invention configured as described above, the threshold pattern determination unit sets the second reflection intensity, which is a variable stored in advance in the reflection intensity storage unit, to one value based on the road surface state. And the threshold pattern is determined based on the determined second reflection intensity, the first reflection intensity and the third reflection intensity stored in advance, and therefore, a large amount of calculation processing is not required and a short time is required. The threshold pattern can be determined.

  The reflection time storage unit stores in advance the first reflection time, the second reflection time, and the third reflection time, and the reflection intensity storage unit stores the first reflection intensity, the second reflection intensity, and the third reflection intensity. By storing in advance, the threshold pattern determination unit can determine the threshold pattern based on these, and therefore, it is possible to reduce the capacity to store in advance as compared with the case of storing a plurality of threshold patterns themselves. Storage capacity can be reduced.

  Furthermore, in the vehicle periphery monitoring device according to the present invention, the road surface state is a degree of road surface unevenness, and the road surface state determination unit is configured to determine the degree of road surface unevenness based on a luminance distribution of the captured image. It is preferable to be configured to determine

  Here, it is possible to detect the presence or absence of an obstacle around the vehicle by using an ultrasonic sonar. However, since the transmission wave transmitted from the ultrasonic sonar has no directivity, a specific obstacle exists. The direction cannot be detected.

  For this reason, a method is generally used in which an ultrasonic sonar and an in-vehicle camera are combined (a fusion sensor system), and a specific position of an obstacle detected by the ultrasonic sonar is determined using an image captured by the in-vehicle camera. ing.

  According to the vehicle periphery monitoring device according to the present invention configured as described above, the road surface state determination unit determines the degree of unevenness on the road surface using an image captured by an in-vehicle camera generally used in a fusion sensor system. Therefore, it is not necessary to provide a special configuration for determining the road surface condition, and the manufacturing cost can be reduced.

  Further, since the road surface state determination unit determines the degree of road surface unevenness based on the luminance distribution of the captured image, the road surface state determination unit can determine the degree of road surface unevenness with relatively little calculation processing.

  Note that determining the degree of road surface unevenness based on the distribution of brightness, for example, if the difference between the maximum brightness and the minimum brightness in the captured image is large, it is determined that the degree of road surface unevenness is large, When the difference between the maximum luminance and the minimum luminance is small, it means that the degree of road surface unevenness is determined to be small.

  And in the vehicle periphery monitoring device according to the present invention, the road surface state determination unit extracts only a predetermined range from the captured image, and based on the luminance distribution of a part of the extracted captured image, It is preferable that the degree of unevenness of the road surface is determined.

  Here, the predetermined range means a range in which the obstacle detection unit can easily receive a reflected wave from the road surface.

  According to the vehicle periphery monitoring device according to the present invention configured as described above, it is possible to further reduce the calculation process for determining the degree of unevenness on the road surface.

  According to the vehicle periphery monitoring device according to the present invention, it is possible to improve the accuracy of detecting obstacles existing around the vehicle by removing the reflected wave from the road surface from the received reflected wave regardless of the road surface state.

1 is a block diagram illustrating a configuration of a vehicle periphery monitoring device 100 according to a first embodiment. It is a schematic diagram which shows the relationship between the unevenness | corrugation degree of a road surface, and the intensity | strength of the reflected wave by a road surface. It is the figure which illustrated the several different threshold value pattern previously memorize | stored in the threshold value pattern memory | storage part 8 of FIG. 5 is a flowchart for explaining a flow of an obstacle detection operation by the vehicle periphery monitoring device 100. It is the figure which illustrated the case where the distribution of the brightness | luminance of a predetermined range is large among the picked-up images by the vehicle-mounted camera 2, and a small case. It is the figure which illustrated the received threshold wave and the threshold pattern P2 determined when the degree of unevenness of the road surface is slightly large. A diagram illustrating the received reflected wave and the determined threshold pattern P1 when the degree of unevenness on the road surface is small, and the threshold value determined as the received reflected wave when the degree of unevenness on the road surface is large It is the figure which illustrated pattern P3. These are figures which show the relationship between the inclination of the road surface with respect to a vehicle, and the reflected wave by a road surface. It is a figure which shows the relationship between the presence or absence of the inclination of the road surface with respect to a vehicle, and the white line in the captured image by the vehicle-mounted camera. The figure which illustrated the received reflected wave and the determined threshold pattern when the road surface inclination with respect to the vehicle is small, and the threshold pattern determined as the received reflected wave when the road surface inclination with respect to the vehicle is large FIG. It is a block diagram which shows the structure of the vehicle periphery monitoring apparatus 200 of Example 2. FIG.

  Hereinafter, based on FIG. 1, the vehicle periphery monitoring apparatus 100 of Example 1 as embodiment of this invention is demonstrated.

  FIG. 1 is a block diagram illustrating a configuration of a vehicle periphery monitoring device 100 according to the first embodiment.

  As shown in FIG. 1, the vehicle periphery monitoring apparatus 100 includes an ultrasonic sonar 1 attached to the vehicle, an in-vehicle camera 2 that images the road surface around the vehicle, and a captured image captured by the in-vehicle camera 2. A road surface state determination unit 3 that determines a road surface state based on the vehicle, an obstacle detection unit 4 that receives a reflected wave of a transmission wave transmitted from the ultrasonic sonar 1 and detects an obstacle existing around the vehicle, a lamp And an output unit 5 that informs the driver of the presence of an obstacle by flashing or generating an alarm sound.

  The ultrasonic sonar 1 is attached to a bumper position or the like at the rear of the vehicle at a height of about 50 cm from the road surface in a horizontal direction with respect to the road surface. The in-vehicle camera 2 is a wide-angle camera, and is installed at a bumper position or the like at the rear of the vehicle with the lens optical axis directed obliquely downward.

  In addition, the obstacle detection unit 4 determines whether or not there is an obstacle using the threshold pattern determination unit 6 that determines one threshold pattern for removing a reflected wave from the road surface, and there is an obstacle. Has a distance measuring unit 7 for measuring the distance from the vehicle to the obstacle.

  The threshold pattern determination unit 6 includes a threshold pattern storage unit 8, and the threshold pattern storage unit 8 stores a plurality of different threshold patterns associated with the road surface state in advance.

  Next, the flow of the obstacle detection operation by the vehicle periphery monitoring device 100 is expressed by [a relation between the degree of unevenness of the road surface and a reflected wave by the road surface], [a plurality of different threshold patterns stored in advance in the threshold pattern storage unit], The description will be divided into [Blockage of Obstacle Detection Action] and [Modification].

[Relationship between degree of unevenness of road surface and reflected wave from road surface]
FIG. 2 is a schematic diagram showing the relationship between the degree of unevenness on the road surface and the intensity of reflected waves from the road surface. FIG. 2A shows a case where the vehicle travels on a road surface (standard road surface) with a small degree of unevenness. 2 (b) shows a situation where the vehicle is traveling on a road surface (gravel road, etc.) with a slightly high degree of unevenness, and FIG. 2 (c) shows a situation where the vehicle is running on a road surface with a high degree of unevenness. Shows the situation.

  First, the case where the ultrasonic sonar 1 attached to the vehicle at a height of about 50 cm from the road surface transmits a transmission wave in the horizontal direction with respect to the road surface will be described.

  In such a case, when a transmission wave is transmitted from the ultrasonic sonar 1, as shown in FIGS. 2A to 2C, this transmission wave is directly received (reverberation) immediately after that. Further, since this transmission wave is a spherical transmission wave, even if it is transmitted in the horizontal direction, it is reflected by the road surface and the reflected wave by the road surface is received.

  The reflected wave from the road surface starts to be received when about 5 msec has elapsed since transmission, regardless of the degree of unevenness of the road surface, and the reflection intensity becomes the highest when about 9 msec has elapsed since transmission, until about 14 msec after transmission. Received.

  In addition, the elapsed time until the reflected wave from the road surface starts to be received (about 5 msec from transmission), the elapsed time until the reflected intensity of the reflected wave from the road surface becomes the highest (about 9 msec from transmission), the reflected wave from the road surface Since the elapsed time (about 14 msec from transmission) until the reception of the sound wave is determined by the installation position of the ultrasonic sonar 1, the installation direction, the spread of the transmission wave, and the like, it is not limited to this value.

  In addition, the reflected wave from the road surface tends to increase in maximum reflection intensity (the intensity of the reflected wave received when about 9 msec elapses from transmission) as the degree of unevenness of the road surface on which the vehicle travels increases.

  In FIG. 2 (FIG. 2, FIG. 8 and FIG. 9 described later), the transmission direction of the transmission wave is the rear direction of the vehicle, but this transmission direction may be any direction around the vehicle.

[Multiple different threshold patterns prestored in the threshold pattern storage unit]
FIG. 3 is a diagram illustrating a plurality of different threshold patterns stored in advance in the threshold pattern storage unit 8 of FIG.

  In the threshold pattern storage unit 8, for example, as shown in FIG. 3, threshold patterns P1, P2, P3, and the like are stored in advance.

  These threshold patterns P1 to P3 are provided with a reverberation countermeasure time threshold so as not to determine the presence or absence of an obstacle for those received until about 2 msec has passed since transmission.

  These threshold patterns P1 to P3 are set so that the maximum reflection intensities at about 5 msec to about 14 msec from transmission are different at about 9 msec from transmission.

  As described above, since the maximum reflected intensity of the reflected wave from the road surface changes according to the degree of unevenness on the road surface, the threshold pattern storage unit 8 stores a plurality of threshold patterns having different maximum reflection intensity at about 9 msec from transmission. By doing so, a threshold pattern associated with the road surface state (the degree of unevenness of the road surface) can be used.

[Flow of obstacle detection]
Next, the flow of the action of determining the threshold pattern according to the degree of unevenness on the road surface and detecting the presence or absence of an obstacle will be described.

  FIG. 4 is a flowchart for explaining the flow of the obstacle detection operation by the vehicle periphery monitoring device 100, and FIG. 5 is a diagram illustrating the case where the luminance distribution of the captured image by the in-vehicle camera 2 is large and small. FIG. 6 is a diagram illustrating the received reflected wave and the determined threshold pattern P2 when the degree of unevenness on the road surface is slightly large, and FIG. 7A shows a small degree of unevenness on the road surface. FIG. 7B is a diagram exemplifying the received reflected wave and the determined threshold pattern P1, and FIG. 7B illustrates the threshold value determined as the received reflected wave when the degree of unevenness on the road surface is large. It is the figure which illustrated pattern P3.

  When the vehicle periphery monitoring device 100 is activated, as shown in FIG. 4, the in-vehicle camera 2 images the road surface around the vehicle, and this captured image is input to the road surface state determination unit 3 (step S1).

  Then, the road surface state determination unit 3 determines the road surface state based on the input captured image (step S2).

  Here, the road surface state means the degree of unevenness on the road surface. As described above, when the ultrasonic sonar 1 is mounted horizontally at a height of about 50 cm from the road surface with respect to the road surface, it depends on the road surface from the time when about 5 msec has passed since transmission regardless of the degree of unevenness of the road surface. The reflected wave starts to be received, and the reflection intensity becomes the highest when about 9 msec elapses from transmission, and is received until about 14 msec elapses after transmission.

  In addition, about 5 msec from the transmission is the time until the reflected wave reflected at a position about 85 cm away from the vehicle is received, and about 9 msec from the transmission is a reflection at a position about 153 cm away from the vehicle. About 14 msec from transmission is the time until the reflected wave reflected at a position about 238 cm away from the vehicle is received.

  That is, when the ultrasonic sonar 1 is mounted at a height of about 50 cm from the road surface and horizontally with respect to the road surface, a reflected wave from the road surface is received within a range corresponding to about 85 cm to about 238 cm from the vehicle. Easy range.

  Therefore, in step 2, the road surface state determination unit 3 that determines the road surface state based on the input captured image captures the road surface within a range of several tens of meters from the vehicle, which is captured by the in-vehicle camera 2 that is a wide-angle camera. A range (predetermined range) corresponding to about 85 cm to about 238 cm from the vehicle is extracted from the image.

  Next, the road surface state determination unit 3 calculates a luminance distribution for a part of the captured image that is the extracted predetermined range. At this time, for example, the luminance value is obtained for each pixel, the maximum luminance and the minimum luminance are obtained from the extracted luminance values of each pixel within the predetermined range, and the difference between the maximum luminance and the minimum luminance is calculated.

  Then, the road surface state determination unit 3 determines that the degree of unevenness of the road surface is large when the difference between the maximum luminance and the minimum luminance is large in the predetermined range extracted as shown in FIG. On the other hand, when the difference between the maximum luminance and the minimum luminance is small in the predetermined range extracted as shown in FIG. 5B, it is determined that the degree of unevenness on the road surface is small.

  Furthermore, the road surface state determination unit 3 outputs information (road surface state pattern) indicating the degree of road surface unevenness determined in step S2 to the threshold pattern determination unit 6 (step S3).

  Based on this information, the threshold pattern determination unit 6 determines one threshold pattern corresponding to the road surface state from among a plurality of different threshold patterns stored in advance in the threshold pattern storage unit 8 as described above. (Step S4).

  For example, in the determination of the road surface state in step S2, when it is determined that the degree of unevenness is a slightly large road surface as shown in FIG. 2B, the threshold value stored in association with such road surface state A pattern (for example, a threshold pattern P2 shown in FIG. 3) is selected.

  After the threshold pattern is determined in step S4, the ultrasonic sonar 1 transmits a transmission wave, and the distance measurement unit 7 provided in the obstacle detection unit 4 receives the reception wave (step S5).

  Further, the distance measuring unit 7 uses the threshold pattern (threshold pattern P2) determined as shown in FIG. 6 to remove the reflected wave from the road surface from the received reflected wave, and the signal after removing the reflected wave from the road surface The presence / absence of an obstacle is determined based on (Step S6).

  Specifically, if the reflected wave remains after removing the reflected wave from the road surface from the received reflected wave, it is determined that there is an obstacle, and if there is no reflected wave, there is no obstacle. Determine (in the situation shown in FIG. 6, it is determined that there is no obstacle).

  If the distance measuring unit 7 determines that there is an obstacle, the distance measuring unit 7 measures the distance from the vehicle to the obstacle (step S7), and outputs information about the distance (distance data) to the output unit 5 (step S7). S8).

  Then, until the operation by the vehicle periphery monitoring device 100 is completed, the determination of the presence or absence of an obstacle (step S5 to step S8) is repeated (step S9). Ends.

  For example, in the determination of the road surface state in step S2, if it is determined that the road surface has a small degree of unevenness as shown in FIG. 2A, the road surface state is stored in association with such a road surface state. A threshold pattern (for example, threshold pattern P3 shown in FIG. 3) is selected (see FIG. 7A), and the presence or absence of an obstacle is detected using this threshold pattern.

  Further, for example, in the determination of the road surface state in step S2, when it is determined that the road surface has a large degree of unevenness as shown in FIG. 2C, the road surface state is stored in association with such a road surface state. The threshold pattern (for example, the threshold pattern P1 shown in FIG. 3) is selected (see FIG. 7B), and the presence or absence of an obstacle is detected using the threshold pattern.

[Modification]
Note that the vehicle periphery monitoring device 100 according to the first embodiment is not limited to determining a threshold pattern according to the degree of unevenness of the road surface, but may determine a threshold pattern according to the inclination of the road surface with respect to the vehicle. .

FIG. 8 is a diagram showing the relationship between the slope of the road surface relative to the vehicle and the reflected wave due to the road surface, and FIG. 8A shows that the slope relative to the vehicle is −5 degrees FIG. 8 (b) shows a situation where the vehicle is traveling on a road surface with a 0 deg inclination relative to the vehicle, and FIG. It shows a situation where the vehicle is traveling on a road surface with an inclination of +5 deg (inclination of 5 degrees uphill).

  For example, when the ultrasonic sonar 1 attached at a height of about 50 cm from the road surface transmits a transmission wave in the horizontal direction with respect to the road surface, when the transmission wave is transmitted, FIGS. 8A to 8C. As shown in FIG. 5, immediately after this, the transmitted wave is directly received (reverberation), and further, the reflected wave from the road surface is received.

  The reflected wave from the road surface tends to increase the maximum reflection intensity of the reflected wave from the road surface and the time to start receiving the reflected wave from the road surface as the inclination angle of the road surface with respect to the vehicle increases.

A plurality of different threshold patterns stored in advance in the threshold pattern storage unit in the modified example As described above, the maximum reflected intensity of the reflected wave from the road surface and the time to start receiving the reflected wave from the road surface are determined by the inclination of the road surface with respect to the vehicle. Accordingly, the threshold value pattern storage unit 8 in the modified example stores a plurality of threshold patterns having different maximum reflection intensity and time to start receiving the reflected wave, and sets the threshold pattern to the road surface state (the inclination of the road surface with respect to the vehicle). It can be used in association with each other.

FIG. 9 is a diagram showing the relationship between the presence / absence of the road surface inclination with respect to the vehicle and the white line in the image taken by the in-vehicle camera 2, and FIG. FIG. 10 is a diagram exemplifying the received reflected wave and the determined threshold pattern when the road surface inclination with respect to the vehicle is small, and FIG. 10B is received when the road surface inclination with respect to the vehicle is large. It is the figure which illustrated the reflected wave and the determined threshold pattern.

  The road surface state determination unit 3 in the modification performs, for example, an overhead conversion process on the image captured by the in-vehicle camera 2, and the two white lines in the subsequent captured image are approximately as shown in FIG. If it is parallel, it is determined that the slope of the road surface with respect to the vehicle is about 0 deg.

  On the other hand, when the two white lines in the captured image after performing the overhead view conversion process are not parallel as shown in FIG. The degree of inclination (angle) of the road surface relative to the vehicle can be determined based on the angle between the white lines (corresponding to twice the angle α shown in FIG. 9B).

  Thus, for example, when it is determined that the road surface has a small inclination with respect to the vehicle, a threshold pattern stored in association with such a road surface state is selected (see FIG. 10A). The presence or absence of an obstacle is detected using the threshold pattern.

  Furthermore, for example, when it is determined that the road surface has a large inclination with respect to the vehicle, a threshold pattern stored in association with such a road surface state is selected (see FIG. 10B). Used to detect the presence or absence of obstacles.

  According to the vehicle periphery monitoring apparatus 100 according to the present invention configured as described above, the road surface state determination unit 3 determines the road surface state based on the captured image of the road surface around the vehicle captured by the in-vehicle camera 2, and the road surface Based on the state, the threshold pattern determination unit 6 determines the threshold pattern, and the obstacle detection unit 4 (the distance measurement unit 7 provided in the obstacle detection unit 4) receives the reflected wave received using the determined threshold pattern. In order to detect the presence or absence of an obstacle based on the signal after removing the reflected wave from the road surface, an appropriate threshold pattern is determined according to the road surface state, and the reflected wave from the road surface from the received reflected wave regardless of the road surface state. By removing, the detection accuracy of obstacles existing around the vehicle can be improved.

  In addition, since the obstacle detection unit 4 detects the presence or absence of an obstacle based on the signal after removing the reflected wave from the road surface from the received reflected wave using the determined threshold pattern, the ultrasonic sonar 1 is used. No special measures to avoid receiving reflected waves from the road surface, such as installing it upwards with respect to the road surface, need to be applied to the ultrasonic sonar 1, maintaining the same distance characteristics as normal ultrasonic sonar can do.

  Moreover, according to the vehicle periphery monitoring apparatus 100 according to the first embodiment, the threshold pattern determination unit 6 includes the threshold pattern storage unit 8 that stores in advance a plurality of different threshold patterns associated with the road surface state. By determining (selecting) one threshold pattern among a plurality of threshold patterns stored in the threshold pattern storage unit 8 based on the road surface state determined by the determination unit 3, the threshold pattern determination unit 6 newly Since it is not necessary to create a threshold pattern and a lot of calculation processing is not required to create the threshold pattern, the threshold pattern can be determined particularly in a short time.

  Furthermore, according to the vehicle periphery monitoring apparatus 100 according to the first embodiment, the road surface state is the degree of road surface unevenness, and the road surface state determination unit 3 determines the degree of road surface unevenness based on the luminance distribution of the captured image. The road surface state determination unit 3 determines the degree of road surface unevenness using an image captured by an in-vehicle camera that is generally used in a fusion sensor system. It is not necessary to provide a simple configuration, and the manufacturing cost can be reduced.

  Further, since the road surface state determination unit 3 determines the degree of road surface unevenness based on the luminance distribution of the captured image, the road surface state determination unit 3 can determine the degree of road surface unevenness with relatively little calculation processing.

  Furthermore, according to the vehicle periphery monitoring apparatus 100 according to the first embodiment, the road surface state determination unit 3 extracts only a predetermined range from the captured image, and based on the luminance distribution of a part of the extracted captured image. By determining the degree of unevenness on the road surface, the calculation process for determining the degree of unevenness on the road surface can be further reduced.

  In addition, about the vehicle periphery monitoring apparatus 100 of Example 1, although the road surface condition determination part 3 demonstrated the form which determines the degree of the unevenness | corrugation of a road surface based on the luminance distribution of a captured image, the vehicle periphery monitoring which concerns on this invention The apparatus is not limited to such a form, and may be configured to determine the degree of unevenness on the road surface using other methods.

  For example, the luminance value is obtained for each pixel, and its variance is calculated. When the variance value is large, it is determined that the degree of road surface unevenness is large, and when the variance value is small, the degree of road surface unevenness is small. A configuration in which it is determined may be adopted.

  Further, in order to increase the influence of the degree of unevenness on the road surface on the distribution and dispersion of luminance, a flash is applied when the road surface around the vehicle is imaged by the in-vehicle camera 2 to emphasize the shadow due to the unevenness on the road surface. In order to reduce the amount of calculation for obtaining the luminance value for each pixel, it is also possible to obtain the luminance for each pixel after binarizing the captured image. .

  In addition to the technique using the luminance distribution of the captured image, for example, a coefficient by a spatial frequency is obtained using discrete cosine transform (DCT), and whether or not a reflected wave from a road surface is easily received based on this coefficient. It can also be configured to determine (the degree of unevenness of the road surface).

  Next, the vehicle periphery monitoring apparatus 200 of Example 2 as an embodiment of the present invention will be described.

  The vehicle periphery monitoring device 200 according to the second embodiment determines a threshold pattern based on the road surface state using the reflection time and the reflection intensity stored in advance, and FIG. 11 illustrates the vehicle periphery monitoring device according to the second embodiment. 2 is a block diagram showing the configuration of 200. FIG.

  As shown in FIG. 11, the vehicle periphery monitoring apparatus 200 according to the second embodiment includes an ultrasonic sonar 21, an in-vehicle camera 22, a road surface state determination unit 23, an obstacle detection unit 24, and an output unit 25. Further, the obstacle detection unit 24 is provided with a threshold pattern determination unit 26 and a distance measurement unit 27.

  The ultrasonic sonar 21 is the same as the ultrasonic sonar 1 (see FIG. 1) of the first embodiment, the in-vehicle camera 22 is the same as the in-vehicle camera 2 of the first embodiment, and the road surface condition determination unit 23 is the first embodiment. The output surface 25 is the same as the output portion 5 of the first embodiment.

  The threshold pattern determining unit 26 includes a reflection time storage unit 28 that stores the first reflection time, the second reflection time, and the third reflection time in advance, and the first reflection intensity, the second reflection intensity, and the third reflection value in the threshold pattern. A reflection intensity storage unit 29 for storing the reflection intensity in advance.

  Here, the first reflection time is an elapsed time from the transmission of the transmission wave by the ultrasonic sonar 21 until the obstacle detection unit 24 starts to receive the reflection wave from the road surface, as described in FIG. Further, the second reflection time is the elapsed time from when the transmission wave is transmitted until the reflection intensity of the reflected wave by the road surface becomes the highest, as described in FIG. Furthermore, the third reflection time is the elapsed time from the transmission of the transmission wave until the reception of the reflected wave by the road surface, which has been described with reference to FIG.

  The first reflection intensity, the second reflection intensity, and the third reflection intensity correspond to the reflection intensity corresponding to the first reflection time, the reflection intensity corresponding to the second reflection time, and the third time, respectively, in the threshold pattern. Reflection intensity.

  As described in the first embodiment, the range in which the reflected wave from the road surface is easily received is determined by the installation position of the ultrasonic sonar 21, the installation direction, the spread of the transmission wave, and the like, so the first reflection time (for example, 5 msec) The second reflection time (for example, 9 msec) and the third reflection time (for example, 14 msec) are also predetermined.

  Further, the first reflection intensity and the third reflection intensity are constant values regardless of the road surface state (for example, voltage 1.5 V), and the second reflection intensity is a variable associated with the road surface state.

  As described in Example 1, the maximum reflected intensity of the reflected wave from the road surface changes according to the degree of unevenness on the road surface, so the second reflected intensity corresponds to the road surface state (the degree of unevenness on the road surface). In addition, it can be stored in the reflection intensity storage unit 29.

  Next, the flow of the obstacle detection operation by the vehicle periphery monitoring device 200 will be described.

  As shown in FIG. 4, when the vehicle periphery monitoring device 200 is activated, the in-vehicle camera 22 images the road surface around the vehicle, and this captured image is the road surface state. The data is input to the determination unit 23 (step S21).

  Then, the road surface state determination unit 23 determines a road surface state based on the input captured image (step S22), and further outputs information (road surface state pattern) regarding the determined road surface state to the threshold pattern determination unit 26 ( Step S23).

  The threshold pattern determination unit 26 to which the information regarding the road surface state is output in step S23 uses the second reflection intensity, which is a variable stored in the reflection intensity storage unit 29 in advance, as the road surface state pattern output from the road surface state determination unit 23. Based on the above, a single value is determined.

  Further, the threshold pattern determination unit 26 determines a threshold pattern based on the determined second reflection intensity, the first reflection intensity and the third reflection intensity stored in advance in the reflection intensity storage unit 29 (step S24). .

  Specifically, the threshold pattern is determined by connecting the first reflection intensity and the second reflection intensity with a straight line, and connecting the second reflection intensity and the third reflection intensity with a straight line.

  After the threshold pattern is determined in step S24, the ultrasonic sonar 21 transmits a transmission wave, and the distance measurement unit 27 provided in the obstacle detection unit 24 receives the reception wave (step S25).

  Then, the distance measuring unit 27 uses the determined threshold pattern to remove the reflected wave from the road surface from the received reflected wave, and determines whether there is an obstacle based on the signal after removing the reflected wave from the road surface. (Step S26).

  If the distance measuring unit 27 determines that there is an obstacle, the distance measuring unit 27 measures the distance from the vehicle to the obstacle (step S27), and outputs information about the distance (distance data) to the output unit 25 (step S27). S28).

  Further, until the vehicle periphery monitoring device 200 is terminated, the determination of the presence or absence of an obstacle (step S25 to step S28) is repeated (step S29). When the vehicle periphery monitoring device 200 is terminated, the obstacle detection operation is terminated.

  According to the vehicle periphery monitoring apparatus 200 according to the second embodiment configured as described above, the following effects can be obtained in addition to the effects of the first embodiment.

  That is, the threshold pattern determination unit 26 transmits the transmission wave by the ultrasonic sonar 21 and the first reflection time from the transmission of the transmission wave by the ultrasonic sonar 21 until the obstacle detection unit 24 starts receiving the reflected wave by the road surface. From the second reflection time until the obstacle detection unit 24 receives the reflected wave having the highest reflection intensity among the reflected waves from the road surface, and from the transmission of the transmission wave by the ultrasonic sonar 21, the obstacle detection unit 24 depends on the road surface. The reflection time storage unit 28 that stores in advance the third reflection time until reception of the reflected wave is completed, the first reflection intensity corresponding to the first reflection time, and the second reflection time corresponding to the second reflection time in the threshold pattern. A reflection intensity storage unit 29 that stores in advance two reflection intensities and a third reflection intensity corresponding to the third reflection time, and the first reflection intensity and the third reflection intensity are constant regardless of the road surface condition. of The second reflection intensity is a variable associated with the road surface state, and the threshold pattern determination unit 26 determines the two reflection intensity based on the road surface state determined by the road surface state determination unit 23, By determining the threshold pattern based on the reflection intensity, the determined second reflection intensity, and the third reflection intensity, the threshold pattern determination unit 26 is a second reflection that is a variable stored in the reflection intensity storage unit 29 in advance. Since the intensity is determined as one value based on the road surface condition, and the threshold pattern is determined based on the determined second reflection intensity, the first reflection intensity stored in advance, and the third reflection intensity, many calculations are performed. The threshold pattern can be determined in a short time without requiring processing.

  The reflection time storage unit 28 stores the first reflection time, the second reflection time, and the third reflection time in advance, and the reflection intensity storage unit 29 stores the first reflection intensity, the second reflection intensity, and the third reflection time. By storing the intensity in advance, the threshold pattern determination unit 26 can determine the threshold pattern based on these, so that the capacity to be stored in advance is smaller than in the case of storing a plurality of threshold patterns themselves. The required storage capacity can be reduced.

  As mentioned above, although the vehicle periphery monitoring apparatus of this invention was demonstrated based on Example 1 and Example 2, it is not restricted to these Examples about a concrete structure, Each claim of a claim Design changes and additions are permitted without departing from the spirit of the invention according to the paragraph.

DESCRIPTION OF SYMBOLS 1 Ultrasonic sonar 2 Car-mounted camera 3 Road surface condition determination part 4 Obstacle detection part 5 Output part 6 Threshold pattern determination part 7 Distance measurement part 8 Threshold pattern storage part 100 Vehicle periphery monitoring apparatus

Claims (5)

An ultrasonic sonar attached to a vehicle; an in-vehicle camera provided on the vehicle for imaging a road surface around the vehicle; a road surface state determination unit for determining a road surface state based on a captured image captured by the in-vehicle camera; An obstacle detection unit that receives the reflected wave of the transmission wave transmitted from the ultrasonic sonar and detects an obstacle present around the vehicle, and
The obstacle detection unit includes a threshold pattern determination unit that determines a threshold pattern for removing the reflected wave from the road surface from the received reflected wave based on the road surface state determined by the road surface state determination unit, and the threshold value A vehicle periphery monitoring device that detects presence / absence of the obstacle based on a signal obtained by removing a reflected wave from the road surface from the received reflected wave using a threshold pattern determined by a pattern determining unit .   The threshold pattern determination unit includes a threshold pattern storage unit that stores in advance a plurality of different threshold patterns that are associated with a road surface state, and stores the threshold pattern pattern based on the road surface state determined by the road surface state determination unit. The vehicle periphery monitoring apparatus according to claim 1, wherein one threshold pattern is determined among the plurality of threshold patterns stored in a unit. The threshold pattern determination unit includes a first reflection time from the transmission of the transmission wave by the ultrasonic sonar until the obstacle detection unit starts receiving the reflected wave by the road surface, and the transmission wave by the ultrasonic sonar. From the transmission of the transmission wave by the ultrasonic sonar to the second reflection time until the obstacle detection unit receives the reflected wave having the highest reflection intensity among the reflected waves from the road surface. A reflection time storage unit that stores in advance a third reflection time until the object detection unit finishes receiving the reflected wave from the road surface;
A first reflection intensity corresponding to the first reflection time, a second reflection intensity corresponding to the second reflection time, and a third reflection intensity corresponding to the third reflection time in the threshold pattern are stored in advance. A reflection intensity storage unit,
The first reflection intensity and the third reflection intensity are constant values regardless of the road surface state, and the second reflection intensity is a variable associated with the road surface state,
The threshold pattern determination unit determines the second reflection intensity based on the road surface state determined by the road surface state determination unit, and the second reflection intensity and the third reflection intensity determined as the first reflection intensity. The vehicle periphery monitoring device according to claim 1, wherein the threshold pattern is determined based on:   The road surface state is a degree of unevenness of the road surface, and the road surface state determination unit determines the degree of unevenness of the road surface based on a luminance distribution of the captured image. The vehicle periphery monitoring device according to any one of the above.   The road surface state determination unit extracts only a predetermined range from the captured image, and determines a degree of unevenness on the road surface based on a luminance distribution of a part of the extracted captured image. The vehicle periphery monitoring apparatus according to any one of claims 1 to 4.