JP2014016962A - Vehicle perimeter monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable vehicle perimeter monitoring system with which obstacles that exist within areas around a vehicle that cannot be seen from a driver's seat can be detected with high accuracy.SOLUTION: A vehicle perimeter monitoring system 10 includes: two stereo camera units 14 and 16 that are located on the upper part of a vehicle and angled to a lower road surface so that images of areas around the vehicle that cannot be seen from a driver's seat can be recorded; image analysis units 18 and 20 that are designed to determine whether or not any obstacles exist according to the images recorded by the stereo camera units 14 and 16; and a warning signal generation unit 22 that is designed to generate a warning signal if it is determined that an obstacle(s) exists according to the image analysis units 18 and 20.

Description

  The present invention relates to a vehicle periphery monitoring system for monitoring a region around a vehicle that becomes a blind spot when viewed from a driver's seat.

  Conventionally, automobiles such as buses and trucks often have blind spots when viewed from the driver's seat in areas below the front and side of the vehicle, and a plurality of mirrors are installed to monitor such blind spots. . As such a mirror, a convex mirror that generally provides a wide field of view is employed.

  On the other hand, it is not easy to visually recognize a plurality of mirrors within a limited time. In addition, there is a situation in which an image obtained through a convex mirror is less likely to have a sense of distance compared to visual observation. Therefore, even if an obstacle such as a person, an animal, or an object is reflected on the mirror, the driver may miss it.

  In contrast, blind spots as viewed from the driver's seat are monitored by cameras, infrared cameras, ultrasonic sensors, etc., and obstacles are automatically recognized. When obstacles exist, a warning is issued or the vehicle starts. There are known systems that prevent the above (for example, see Patent Documents 1 to 7). By using such a system, it is expected to prevent the vehicle from colliding with or contacting an obstacle in the blind spot.

Japanese Patent No. 4751894 JP 2008-254710 A JP 2008-68675 A Japanese Patent Laid-Open No. 3-14100 Japanese Patent No. 3890878 Japanese Patent No. 4670359 Japanese Patent Laid-Open No. 62-273477

  However, even if an object that may be an obstacle is captured by the camera, it may be difficult to automatically determine whether or not the object is an obstacle. For example, if there is a part of the road surface that is different in color from the surrounding area, or if garbage such as paper scraps has fallen on the road, such a part of the road surface or only existing near the road surface is recognized as an obstacle. Although it should not be done, it is not possible to identify whether these are part of the road surface, only near the road surface, or higher positions only with the camera image data. It is difficult to automatically exclude these from obstacles. In contrast, infrared cameras are effective for identifying humans and animals, but infrared cameras are susceptible to sunlight. For example, in the daytime when the sun is strong, it is a blind spot as seen from the driver's seat. Even if there are people or animals, they may not be recognized correctly. It should be noted that a camera that targets a normal visible light region may not be able to accurately recognize an object to be measured when direct sunlight enters. On the other hand, since the ultrasonic sensor can grasp the distance, it is possible to distinguish between a part of the road surface or only existing near the road surface and a higher position, Although not affected by sunlight, the ultrasonic sensor has excellent accuracy in measuring the distance between itself and the measurement object, but is not suitable for measuring the size of the measurement object. For this reason, it may be difficult to distinguish an object having a size that should not be recognized as an obstacle and a size that should be recognized as an obstacle.

  The present invention has been made in view of the above problems, and provides a highly reliable vehicle periphery monitoring system capable of detecting an obstacle existing in a region around the vehicle that becomes a blind spot when viewed from the driver's seat with high accuracy. The issue is to provide.

  The present invention relates to a stereo camera unit installed on an upper part of a vehicle toward a lower road surface so as to image an area around the vehicle that becomes a blind spot when viewed from a driver's seat, and an obstacle based on an image captured by the stereo camera unit An image analysis unit configured to determine whether there is an obstacle, and a warning signal transmission unit configured to transmit a warning signal when the image analysis unit determines that an obstacle exists. The above problem is solved by a vehicle periphery monitoring system provided.

  Since this vehicle periphery monitoring system uses a stereo camera unit, the distance to the measurement object and the size of the measurement object can be recognized with high accuracy. Moreover, since the stereo camera unit is installed toward the road surface below, it is not easily affected by sunlight. Therefore, it is possible to detect an obstacle present in the area around the vehicle that becomes a blind spot when viewed from the driver's seat with high accuracy.

  Note that the image analysis unit determines the distance between the stereo camera unit and a plurality of points on the standard road surface corresponding to the plurality of pixels of the stereo camera unit when the stereo camera unit images a standard road surface on which no obstacle exists. Is stored in advance as reference data, and distances between the plurality of points corresponding to the plurality of pixels in the image actually captured by the stereo camera unit and the stereo camera unit are calculated, and this calculated measurement is calculated. A set of points whose distance data values are within a predetermined range close to each other and within a predetermined height from the standard road surface are identified as objects different from the road surface and their sizes. It is good to be comprised so that it may be judged that an obstruction exists when the presence of the object of a predetermined size is recognized.

  Thus, by determining whether or not the measurement distance data values are close to each other for a plurality of points in the image corresponding to a plurality of pixels of the stereo camera unit, the presence of the object and the size of the object can be determined. It can be recognized with high accuracy. In addition, by judging whether or not it is a set of points that exist within a predetermined height range from the standard road surface based on the reference data, it is present only on a part of the road surface or near the road surface. Can be distinguished. Therefore, an obstacle can be recognized accurately.

  Further, the difference data obtained by subtracting the measurement distance data value from the reference data value is calculated for each of a plurality of points corresponding to the plurality of pixels, and the difference data value is a value within a predetermined range close to each other. In addition, a set of points whose difference data value is equal to or greater than a predetermined threshold may be recognized as an object different from the road surface. By using such difference data, it is possible to simplify the calculation for determining the presence of an object different from the road surface and the size of the object.

  Also, a warning light for notifying the presence of an obstacle by lighting or blinking based on the warning signal, and at least one warning notification means of a warning sound generator for notifying the presence of the obstacle by sound based on the warning signal It is good to have more. By providing the warning notification means in this way, it is possible to notify the driver or a person around the vehicle of the presence of an obstacle.

  Moreover, you may further provide the interlock means which inhibits start of a vehicle based on a warning signal. By providing the interlock means in this way, it is possible to avoid a situation where the vehicle starts with an obstacle in the blind spot.

  Further, the stereo camera unit may have a configuration in which two cameras are accommodated in one housing. If the two cameras are housed in one housing in this way, the stereo camera unit can be easily installed and handled.

  Further, it is preferable that the side surface is inclined so that at least a portion in the vicinity of the end portion on the side facing the line of sight of the stereo camera unit in the housing becomes narrower toward the line of sight. In addition to the stereo camera unit being installed toward the lower road surface, in this way, at least the portion in the vicinity of the end of the stereo camera unit on the side toward which the line of sight is directed in the housing is such that the side becomes narrower toward the line of sight. Is inclined, for example, even when a stereo camera unit is installed outside the vehicle, it is difficult for rainwater or the like to adhere to the light incident surface of the stereo camera unit, and high monitoring accuracy can be maintained.

  ADVANTAGE OF THE INVENTION According to this invention, the reliable vehicle periphery monitoring system which can detect the obstacle which exists in the area | region of the vehicle periphery which becomes a blind spot seeing from a driver's seat with high precision is realizable.

The block diagram which shows typically the structure of the vehicle periphery monitoring system which concerns on embodiment of this invention A perspective view schematically showing a bus provided with the vehicle periphery monitoring system The top view which shows typically the blind spot below the vehicle front surface of the said bus | bath, and the area | region of the circumference | surroundings The perspective view which shows typically the blind spot below the vehicle left side surface of the bus | bath, and the area | region of the circumference | surroundings Front view showing the appearance of a stereo camera constituting the vehicle periphery monitoring system Plan view Side view The perspective view which shows typically the blind spot below the left side surface of the vehicle on the standard road surface without an obstacle and the surrounding area

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. This embodiment relates to a vehicle periphery monitoring system 10 as shown in FIG. The vehicle periphery monitoring system 10 is provided in a bus 12 as shown in FIG.

  The vehicle periphery monitoring system 10 includes two stereo camera units 14 and 16 installed on the upper part of the vehicle toward a lower road surface so as to capture an area around the vehicle that becomes a blind spot when viewed from the driver's seat, and a stereo camera unit. The image analysis units 18 and 20 configured to determine whether or not an obstacle exists based on the captured images 14 and 16 and the image analysis units 18 and 20 determine that an obstacle exists. A warning signal transmitter 22 configured to transmit a warning signal, a warning lamp 24 for notifying the driver of the presence of an obstacle based on the warning signal by lighting or blinking, and an obstacle signal based on the warning signal An in-vehicle buzzer (warning sound generator) 26 for notifying the driver of the presence by sound, and an out-of-vehicle speaker system for notifying the presence of an obstacle by sound based on the warning signal A beam (warning sound generator) 28, and a interlocking means 30 for inhibiting the starting of the vehicle, the based on the warning signal. In the present application, the term “obstacle” is used to include humans and animals.

  The stereo camera unit 14 is installed at the upper part of the front end of the vehicle so as to image the road surface below the front of the vehicle as shown in FIG. More specifically, the stereo camera unit 14 is installed in a posture in which the line of sight faces a direction slightly inclined from the vertically lower side to the front side near the ceiling at the front end in the vehicle. 2 and 3, a trapezoidal portion on the road surface drawn as a shade under the front of the vehicle schematically shows a confirmation target range (range in which the presence or absence of an obstacle is confirmed) in the imaging range of the stereo camera unit 14. It is shown. As shown in FIG. 3, a portion close to the front surface of the bus 12 in the imaging range of the stereo camera unit 14 is a blind spot as viewed from the driver's seat. It should be noted that the portion before the confirmation target range of the stereo camera unit 14 can be directly viewed from the driver's seat.

  On the other hand, the stereo camera unit 16 is installed at the left end of the front end of the vehicle so as to image the road surface below the left side of the vehicle as shown in FIG. More specifically, the stereo camera unit 16 is attached to a stay supporting a mirror outside the vehicle on the upper left side of the front end of the vehicle in a posture in which the line of sight is directed from the vertically downward direction to the rear side. FIG. 4 is an image of the stereo camera unit 16, and in FIGS. 2 and 4, a rectangular portion on the road surface drawn as a shade on the lower left side of the vehicle is a confirmation target range (of the imaging range of the stereo camera unit 16 ( The range in which the presence or absence of an obstacle is confirmed is schematically shown. Most of the imaging range of the stereo camera unit 16 is a blind spot as seen from the driver's seat. The driver can visually recognize the blind spot below the front of the vehicle and the blind spot below the left side of the vehicle through a mirror outside the vehicle.

  Next, the configuration of the stereo camera units 14 and 16 will be briefly described. Since the stereo camera units 14 and 16 have the same configuration, the same components are denoted by common reference numerals, and redundant description will be omitted. The stereo camera units 14 and 16 each have a first camera 32 and a second camera 34, and the first camera 32 and the second camera 34 are predetermined so as to be able to image a common imaging target. The base line length is set apart. The first camera 32 and the second camera 34 have the same configuration, and include a lens 36 and an image sensor 38, respectively. The image sensor 38 is, for example, a CMOS image sensor or a CCD image sensor. The base line length (interval of the optical axis of the lens 36) of the first camera 32 and the second camera 34 is, for example, 4 to 16 cm (8 cm as an example). Further, the stereo camera units 14 and 16 have an appearance as shown in FIGS. 5 to 7, and are configured such that the first camera 32 and the second camera 34 are accommodated in one housing 40. The side surface of the case 40 in the vicinity of the end of the stereo camera units 14 and 16 on the side facing the line of sight is inclined so as to become narrower in the direction of the line of sight. 5 to 7 are a front view, a plan view, and a side view of the stereo camera unit 14 (16), respectively, which are a front view when the stereo camera units 14 and 16 are viewed from the side facing the line of sight. This is different from the view of the state installed on the bus 12. For example, in the case of the stereo camera unit 14, FIGS. 5 to 7 are a bottom view, a front view, and a side view in a state where the stereo camera unit 14 is installed on the bus 12.

  The image analysis units 18 and 20 correspond to the stereo camera units 14 and 16, respectively, and are accommodated in the housing 40 of the stereo camera units 14 and 16. The image analysis units 18 and 20 have the same hardware configuration, and each include an FPGA (Field-Programmable Gate Array) 42, a data memory 44, and a microcontroller 46.

The FPGA 42 is configured to calculate distances from the stereo camera units 14 and 16 to a plurality of points corresponding to a plurality of predetermined pixels in the image based on the parallax of the first camera 32 and the second camera 34. Has been. More specifically, the FPGA 42 removes distortion of the lenses 36 of the first camera 32 and the second camera 34 and then distances to points corresponding to the respective pixels based on signals of predetermined pixels of the image sensor 38. Is calculated. More specifically, the FPGA 42 specifies, in the image sensor 38 of the second camera 34, a pixel having the same brightness as a predetermined pixel of the image sensor 38 of the first camera 32. Since the first camera 32 and the second camera 34 image the measurement object from a position separated by the base line length, the positions of the pixels having the same luminance (in the respective image sensors 38) do not match. The FPGA 42 calculates the distance to the point corresponding to the pixel based on the positional deviation amount. Specifically, if the baseline length of the first camera 32 and the second camera 34 is B, the focal length is F, and the amount of positional deviation (in the image sensor 38) of pixels having the same luminance is Z, the distance calculation target point is reached. Is calculated by the following equation.
L = B × F / Z

  When the image sensor 38 is a monochrome image sensor, the plurality of pixels whose distances are to be calculated may be all of the pixels of the image sensor 38 or some predetermined pixels. On the other hand, when the image sensor 38 is a color image sensor having three types of R, G, and B pixels, the distance calculation target pixels are all one type of R, G, and B pixels. Alternatively, it may be a predetermined part (plural) of pixels of any one type of R, G, and B. In the case of a color imaging device in which R, G, and B pixels are arranged in a Bayer array, the number of G pixels is larger than the number of R and B pixels, and therefore it is preferable to calculate the distance for the G pixels.

  The data memory 44 is a standard corresponding to the predetermined plurality of pixels of the stereo camera units 14 and 16 when the stereo camera units 14 and 16 image a standard road surface having no obstacle as shown in FIG. The distances between a plurality of points on a typical road surface and the stereo camera units 14 and 16 are stored in advance as reference data. FIG. 8 schematically shows a portion of the standard road surface below the left side surface of the vehicle. A rectangular portion on the road surface drawn as shaded in FIG. 8 represents a stereo on the standard road surface. This corresponds to the confirmation target range in the imaging range of the camera unit 16. On the other hand, although the illustration of the confirmation target range in the imaging range (below the front of the vehicle) of the stereo camera unit 14 on the standard road surface is omitted, it is on the road surface drawn as a shade in the lower front of the vehicle in FIG. It looks like a trapezoidal part. For example, the reference data may be obtained by actually capturing an actual standard road surface (for example, a sufficiently flat road surface) with the stereo camera units 14 and 16 and pressing a predetermined switch. . When the installation positions and installation angles of the stereo camera units 14 and 16 are known in advance, the standard road surface may be a virtual road surface. When the standard road surface is a virtual road surface, the reference data can be obtained by capturing image data of the virtual road surface.

  The microcontroller 46 has a measurement distance data value calculated by the FPGA 42 within a predetermined range close to each other and within a predetermined height or more (for example, 300 mm or more) from the standard road surface. If a set of points to be detected is identified as an object different from a part of the road surface or only near the road surface, its size is calculated, and an obstacle exists when the presence of an object of a predetermined size is recognized It is comprised so that it may judge. Here, the predetermined size is, for example, the size of a human or a size corresponding to a human having a large baggage (the size of a combination of a baggage and a human), for example, the width (in the horizontal direction) is 300 mm or more. It is a size. Note that the microcontroller 46 may have a function of determining that an obstacle exists in the blind spot only when the size of the object is determined to be equivalent to a human. Further, the microcontroller 46 has a function of discriminating whether or not the object is a human body by performing image analysis on the shape of the object, and determining that an obstacle exists in the blind spot when the object is determined to be a human being. Good. In addition, the microcontroller 46 identifies an object that should not be recognized as an obstacle such as the bus stop sign shown in FIG. 4 by comparing it with a predetermined template, and excludes it from the object that should be recognized as an obstacle. It may have a function.

  More specifically, the FPGA 42 calculates difference data obtained by subtracting the measurement distance data value from the reference data value for each of a plurality of points in the image corresponding to the plurality of pixels, and the data memory 44 is calculated by the FPGA 42. The difference data is stored, and the microcontroller 46 determines a set of points where the values of the difference data are values within a predetermined range close to each other, and the values of the difference data are equal to or greater than a predetermined threshold (for example, 300 mm or more). It is configured so as to be recognized as an object that is different from a part of the road surface or an object that exists only near the road surface.

  More specifically, the microcontroller 46 recognizes a set of points whose difference data values calculated by the FPGA 42 are equal or whose difference data values are below a certain threshold value (for example, 300 mm or less) as a single object. Is configured to do. In addition, the microcontroller 46 is configured to recognize a set of points whose difference data calculated by the FPGA 42 is equal to or more than another certain threshold (for example, 300 mm or more) as an object different from the road surface. Note that the upper limit value of the difference value of the difference data is set to a small value, for example, about several mm, and it is determined whether the difference data value is equal or the difference data value difference is equal to or less than a certain threshold value. For example, the measurement may be performed every two points corresponding to two adjacent pixels among a plurality of pixels to be measured. In this case, even if the difference between the values of the difference data of two points corresponding to two pixels that are not adjacent to each other among the pixels to be measured for distance is larger than a certain threshold value, If the difference between the values of the difference data of the points corresponding to the other two adjacent (distance measurement target) pixels existing between the pixels is less than a certain threshold, the set of these points is regarded as a lump of objects. Will be recognized. For example, when a spherical object such as a human head is imaged, there is a large difference in the value of difference data between a point near the center of the sphere and a point near the contour, but exists between these points. If the difference between the values of the difference data of two adjacent points among the distance measurement target points is a small value that is not more than a certain threshold value, the spherical object is recognized as a lump object. The microcontroller 46 calculates the size of the object based on the measured distance data value calculated by the FPGA 42, the horizontal angle of view of the lens 36, and the number of pixels corresponding to the point on the object. ing.

  The warning signal transmission unit 22 is a microcontroller provided outside the housing 40 of the stereo camera units 14 and 16. The warning signal transmission unit 22 is connected to the microcontroller 46 of the image analysis unit 18 corresponding to the stereo camera unit 14 and also to the microcontroller 46 of the image analysis unit 20 corresponding to the stereo camera unit 16. The warning signal transmission unit 22 is also connected to a buffer 48 to which a signal indicating whether or not the parking brake is applied and a level converter 50 to which a vehicle speed pulse signal is input. Further, the warning signal transmitter 22 is also connected to a warning lamp 24, an in-vehicle buzzer 26, an in-vehicle speaker system 28, and an interlock means 30. The pulse signal of the vehicle speed has a basic unit of 1000 pulses for a mileage of about 1 mile (about 1609 m), and generates 4 times, 8 times, 16 times, 20 times and 25 times as many pulses as this basic unit. The device is provided in a drive system part (for example, on the output shaft side of the transmission) (not shown).

  The warning signal transmission unit 22 determines that there is an obstacle in the blind spot below the front of the vehicle by the image analysis unit 18 corresponding to the stereo camera unit 14 when the vehicle is stopped and the parking brake is released. In this case, a warning signal is transmitted.

  The warning signal transmission unit 22 corresponds to the stereo camera unit 16 in a state where the vehicle is stopped or slowing down at a predetermined speed or less (for example, 20 km / h or less) and the parking brake is released. Even when it is determined by the image analysis unit 20 that there is an obstacle in the blind spot below the left side surface of the vehicle, a warning signal is transmitted.

  The warning lamp 24 is installed at a position where the driver around the driver's seat can easily see the driver while sitting on the driver's seat. The warning lamp 24 is lit or blinked by a warning signal transmitted from the warning signal transmitter 22.

  The in-vehicle buzzer 26 is directly driven by a warning signal transmission unit (microcontroller) 22. On the other hand, the vehicle exterior speaker system 28 includes a synthesized voice generator 52, a speaker amplifier 54, and a vehicle exterior speaker 56. The synthesized voice generator 52 receives a warning signal transmitted from the warning signal transmission unit 22 and transmits a signal corresponding to a predetermined voice or an alarm, and the signal is amplified by the speaker amplifier 54 and is obstructed from the speaker 56 outside the vehicle. The sound and the alarm of the content which informs the existence of are to be issued. The synthesized sound generator 52 is different between the case where the stereo camera unit 14 determines that an obstacle exists below the front of the vehicle and the case where the stereo camera unit 16 determines that an obstacle exists below the left side of the vehicle. You may be comprised so that a different signal may be transmitted so that a sound or an alarm may be emitted.

  The interlock means 30 is configured to inhibit the start of the vehicle, for example, by holding the transmission neutral. More specifically, when the transmission is a type of transmission in which shifting (gear switching) is performed by electrical control, such as an automatic transmission or an electric / pneumatic manual transmission, the warning signal transmission unit 22 transmits a warning signal. Then, the start of the vehicle can be inhibited by configuring the microcontroller that controls the transmission to control the transmission to be neutral. Further, the interlock means 30 may be configured to inhibit the start of the vehicle by stopping the rotation of the engine. More specifically, in the case of an engine of a type in which the fuel injection amount is increased or decreased by electrical control, even if the accelerator pedal is depressed when the warning signal transmission unit 22 transmits a warning signal, a micro for controlling the fuel injection amount By configuring the controller to perform control to stop fuel injection, the start of the vehicle can be inhibited. Further, the interlock means 30 may be configured to inhibit the start of the vehicle by automatically applying a brake. More specifically, the brake is operated by air, liquid, or a combination of air and liquid so that the valve for applying pressure to the air or liquid in the brake pipe is electrically controlled. In the case of the type of brake system, when the warning signal transmission unit 22 transmits a warning signal, the valve is operated so as to apply pressure to the air or liquid in the brake pipe, thereby inhibiting the start of the vehicle. it can. Moreover, the structure which inhibits start of a vehicle may be used by using two or three of these transmissions, engines, and brakes in combination. Note that specific examples of the structure of the interlock means 30 include a microcomputer and an electric circuit including a relay. When the interlock means 30 is a microcomputer, it may be a dedicated microcomputer for the interlock, but the microcontroller of the warning signal transmitter 22, the microcontroller for controlling the transmission, the fuel injection amount of the engine A microcontroller for controlling the control or a microcontroller for controlling a brake valve may also serve as the function of the interlock means 30.

  Next, the operation of the vehicle periphery monitoring system 10 will be described. For example, in a state where the bus 12 is stopped at a stop or the like, a pulse signal of the vehicle speed is not input to the level converter 50, whereby the warning signal transmission unit 22 recognizes that the bus 12 is stopped. In addition, when the driver applies the parking brake, a signal indicating that the parking brake is applied is input to the buffer 48, whereby the warning signal transmission unit 22 recognizes that the parking brake is applied. To do. On the other hand, when the driver releases the parking brake to start the bus 12, a signal indicating that the parking brake is applied is not input to the buffer 48, whereby the warning signal transmission unit 22 releases the parking brake. Recognize that

  The stereo camera units 14 and 16 respectively capture an area around the vehicle including a blind spot below the front of the vehicle and a blind spot below the left side of the vehicle. The image analysis units 18 and 20 are based on the captured images of the stereo camera units 14 and 16. To determine whether there is an obstacle. When an obstacle such as a person, an animal, or an article exists below the front of the vehicle or below the left side of the vehicle, the obstacle is imaged by the stereo camera units 14 and 16 and is determined to be present by the image analysis units 18 and 20. Is done.

  Since the vehicle periphery monitoring system 10 uses the stereo camera units 14 and 16, the distance to the measurement object and the size of the measurement object can be recognized with high accuracy. Moreover, since the stereo camera units 14 and 16 are installed toward the road surface below, they are not easily affected by sunlight. Therefore, it is possible to detect an obstacle present in the area around the vehicle that becomes a blind spot when viewed from the driver's seat with high accuracy.

  Further, by determining whether or not the measurement distance data values (difference data values) are close to each other at a plurality of points in the image corresponding to the plurality of pixels of the stereo camera units 14 and 16, the object And the size of the object can be recognized with high accuracy. In addition, by judging whether or not it is a set of points that exist within a predetermined height range from the standard road surface based on the reference data, it can be distinguished from those that are part of the road surface or those that are close to the road surface. can do. Therefore, an obstacle can be recognized accurately. Further, by using the difference data, it is possible to simplify the calculation for determining the presence of an object different from the road surface and the size of the object.

  If the image analysis units 18 and 20 determine that an obstacle exists, the warning signal transmission unit 22 transmits a warning signal. As a result, the warning lamp 24 is turned on or flashes, and the driver can visually know that there is an obstacle in the blind spot. In addition, the buzzer 26 in the vehicle issues an alarm, so that the driver can also know audibly that there is an obstacle in the blind spot. In addition, the speaker 56 outside the vehicle also emits a sound or an alarm so that a person in the blind spot can audibly know that he is in the blind spot. Also, other people around the bus 12 can audibly know that there are obstacles such as people, animals, and articles in the blind spot.

  Further, the interlock means 30 inhibits the start of the vehicle by holding the transmission in neutral, stopping the rotation of the engine, or applying a brake. As a result, it is possible to avoid a situation in which the vehicle starts in a state where there is an obstacle in a blind spot such as the lower front of the vehicle.

  The stereo camera units 14 and 16 are configured so that the first camera 32 and the second camera 34 are accommodated in a single housing 40, respectively, so that they can be easily installed and handled.

  Further, in addition to the stereo camera units 14 and 16 being installed toward the lower road surface, a portion in the vicinity of the end portion on the side where the line of sight of the stereo camera units 14 and 16 in the housing 40 is directed toward the line of sight. Since the side surfaces are inclined so as to be thin, even when installed outside the vehicle like the stereo camera unit 16, rainwater or the like is hardly attached to the light incident surface, and high monitoring accuracy can be maintained.

  In this embodiment, the stereo camera unit 14 is installed near the ceiling at the front end in the vehicle, but the stereo camera unit 14 may also be installed outside the vehicle like the stereo camera unit 16. For example, the stereo camera unit 14 may be attached to a stay that supports a mirror outside the vehicle on the upper left side of the front end of the vehicle. In this case, the stereo camera unit 14 is attached in a posture in which the line of sight faces the direction inclined from the vertically lower side to the right side.

  In the present embodiment, the vehicle periphery monitoring system 10 includes a stereo camera unit 14 for imaging a blind spot at the lower front of the vehicle and a stereo camera unit 16 for capturing a blind spot at the lower left of the vehicle. In addition to these, a stereo camera unit for imaging a blind spot below the right side of the vehicle and a stereo camera unit for imaging a blind spot below the rear of the vehicle may be provided.

  In the present embodiment, the warning signal transmission unit 22 determines that there is an obstacle in the blind spot below the front of the vehicle based on the image captured by the stereo camera unit 14 and the vehicle based on the image captured by the stereo camera unit 16. The same warning signal is sent when it is determined that there is an obstacle in the blind spot below the left side, but when there is an obstacle in the blind spot below the front of the vehicle, The warning signal transmitter 22 may transmit different warning signals when it is determined that there is an obstacle in the blind spot. Accordingly, for example, the interlock means 30 does not operate only when it is determined that an obstacle exists in the blind spot below the left side of the vehicle, and the interlock means 30 operates only when an obstacle exists in the blind spot below the front of the vehicle. You may do it.

  In the present embodiment, the vehicle periphery monitoring system 10 includes the interlock unit 30. However, it is sufficient that the driver or the like can recognize the presence of an obstacle in the blind spot by a warning notification unit such as a warning lamp 24. In such a case, the vehicle periphery monitoring system 10 may not include an interlock unit.

  In the present embodiment, the vehicle periphery monitoring system 10 includes a warning light 24, an in-vehicle buzzer 26, and an outside speaker system 28 as warning notification means. However, any two or only one of them is provided. However, when the driver or the like can sufficiently recognize the presence of an obstacle in the blind spot, the vehicle periphery monitoring system 10 is configured to include any two or only one of them as warning notification means. There may be. For example, the structure provided only with the warning light 24 may be sufficient.

  In this embodiment, the warning signal transmission unit 22 is provided outside the housing 40 of the stereo camera units 14 and 16, but the warning signal transmission unit 22 is provided in either case of the stereo camera units 14 and 16. It may be accommodated in the body 40.

  In the present embodiment, the image analysis units 18 and 20 are housed in the housings 40 of the stereo camera units 14 and 16, respectively, but the image analysis units 18 and 20 are housed in the stereo camera units 14 and 16. It may be installed outside the body 40.

  In the present embodiment, the image analysis units 18 and 20 and the warning signal transmission unit 22 are each configured with a dedicated microcontroller. However, two or three of these functions share a common one. A configuration in which one microcontroller is responsible may be employed.

  In the present embodiment, the image analysis units 18 and 20 allow the FPGA 42 to calculate difference data obtained by subtracting the value of the measurement distance data from the value of the reference data for each of a plurality of points, and a part of the road surface based on the difference data. Or, it is configured to recognize as an object different from the object that exists only near the road surface, but based on the value of the measurement distance data regardless of the difference data, a predetermined range in which the values of the measurement distance data are close to each other It may be determined whether or not the object exists by directly determining whether or not the value is within the range. In this case as well, an object that is different from a part of the road surface or only near the road surface is determined by determining whether the position of the object is higher than a predetermined height with respect to the standard road surface. It is possible to determine whether or not.

  In this embodiment, the vehicle periphery monitoring system 10 is applied to a bus. However, the vehicle periphery monitoring system 10 can be applied to an automobile other than a bus such as a truck, a tractor, and a passenger car.

  The present invention can be used for automobiles such as buses.

DESCRIPTION OF SYMBOLS 10 ... Vehicle periphery monitoring system 12 ... Bus 14, 16 ... Stereo camera unit 18, 20 ... Image analysis part 22 ... Warning signal transmission part 24 ... Warning light 26 ... In-vehicle buzzer (warning sound generator)
28 ... Outside speaker system (warning sound generator)
DESCRIPTION OF SYMBOLS 30 ... Interlock means 32 ... 1st camera 34 ... 2nd camera 36 ... Lens 38 ... Image pick-up element 40 ... Housing | casing 42 ... FPGA
44 ... Data memory 46 ... Microcontroller 48 ... Buffer 50 ... Level converter 52 ... Synthetic voice generator 54 ... Speaker amplifier 56 ... External speaker

Claims (7)

A stereo camera unit installed at the top of the vehicle toward the lower road surface so as to image an area around the vehicle that becomes a blind spot when viewed from the driver's seat;
An image analysis unit configured to determine whether an obstacle exists based on a captured image of the stereo camera unit;
A vehicle periphery monitoring system, comprising: a warning signal transmitter configured to transmit a warning signal when it is determined by the image analysis unit that an obstacle exists. In claim 1,
The image analysis unit includes a plurality of points on the standard road surface corresponding to a plurality of pixels of the stereo camera unit and a stereo camera unit corresponding to a plurality of pixels of the stereo camera unit when a standard road surface without an obstacle is imaged by the stereo camera unit. And the distance between the plurality of points corresponding to the plurality of pixels in the image actually captured by the stereo camera unit and the distance between the stereo camera unit, The calculated measurement distance data value is a value within a predetermined range close to each other, and a set of points existing within a predetermined height or more from the standard road surface is defined as an object different from the road surface. It is judged and the size is calculated, and it is judged that an obstacle exists when the existence of an object of a predetermined size is recognized. Vehicle environment monitoring system characterized in that it is configured to. In claim 2,
The image analysis unit calculates difference data obtained by subtracting the value of the measurement distance data from the value of the reference data for each of a plurality of points corresponding to the plurality of pixels, and the value of the difference data is a predetermined value close to each other. A vehicle periphery monitoring system configured to recognize a set of points which are values within a range and whose difference data value is equal to or greater than a predetermined threshold as objects different from a road surface. In any one of Claims 1 thru | or 3,
A warning light for notifying the presence of the obstacle by lighting or blinking based on the warning signal and a warning notification of at least one of a warning sound generator for notifying the presence of the obstacle by sound based on the warning signal The vehicle periphery monitoring system further comprising means. In any one of Claims 1 thru | or 4,
A vehicle periphery monitoring system, further comprising an interlock unit that inhibits starting of the vehicle based on the warning signal. In any one of Claims 1 thru | or 5,
The stereo camera unit has a configuration in which two cameras are housed in one housing. In claim 6,
The vehicle periphery monitoring system characterized in that a side surface is inclined so that at least a portion in the vicinity of an end portion on the side facing the line of sight of the stereo camera unit in the housing is narrowed toward the line of sight.