JP2007017246A - Distance measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a "distance measuring system" capable of measuring the distance of an object at a low cost by utilizing auto-focus technology used for a photographing camera. <P>SOLUTION: The distance measuring system for measuring the distance to an object by utilizing a photographing camera for loading on a vehicle has a photographing camera for photographing at least part around a vehicle, a focus control means (40, 42, 44 and 16) for controlling the position of a lens 34 so as to adjust the focus of the lens 34 of the camera to subjects A and B, and a distance calculating means 16 for calculating the distances D1 and D2 to the subjects A and B when the focus is adjusted to the subjects A and B. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a distance positioning device that measures the distance from a vehicle to an object, and more particularly, to a distance positioning technique using an autofocus function of an imaging camera mounted on the vehicle.

  A driving support system has been put into practical use in which an imaging camera or a distance measuring device is mounted on a vehicle and a warning is given by voice or video when a situation that may cause danger or obstacle to driving is detected. For example, there are distance measuring devices that use radar or ultrasonic waves, and a radar or ultrasonic wave emitting device and a receiving device that receives reflected waves from the object are attached to the front of the vehicle. The distance is measured. In addition, the imaging camera uses, for example, a CCD element or a CMOS sensor, and a single or a plurality of imaging cameras are attached to the vehicle, and images of the front and rear of the vehicle are taken. The space is imaged and these are displayed on the display.

  Patent Document 1 relates to an in-vehicle image display device, which captures left and right landscapes with cameras mounted on the left and right sides of a vehicle. This image is displayed on a display by a control unit when approaching an intersection with poor visibility. Is done. Based on the distance to the subject measured using the focus function of the camera, and by image processing in the image processing unit, it is determined whether the captured image captures a road extending in the lateral direction of the vehicle. An arrow image for route guidance is combined with a landscape image only when is photographed. Thereby, easy-to-understand route guidance is displayed.

JP-A-11-348659

  As described above, some distance measuring devices mounted on a vehicle use radar and ultrasonic waves, but they require expensive devices, special mechanisms, etc., and thus increase the cost. I have it. On the other hand, Patent Document 1 uses a camera focus function to determine whether a subject is a short distance or a long distance. However, this alone cannot accurately calculate the distance to the subject. It is not a substitute for a distance measuring device.

An object of the present invention is to provide a distance positioning device that can accurately measure the distance to a subject by using an autofocus technique used in an imaging camera.
A further object of the present invention is to provide a low-cost distance positioning device that uses an in-vehicle imaging camera for distance positioning.
Furthermore, an object of the present invention is to provide a navigation device that can correct the position of the host vehicle using the distance positioning device described above.

  A distance measuring device that measures a distance to an object using an in-vehicle imaging camera according to the present invention includes an imaging camera that captures at least a part of the periphery of a vehicle, and the focus of a lens or a lens group of the imaging camera on the subject. Focus control means for adjusting the position of at least one lens so as to match, and distance calculation means for calculating the distance to the subject based on the position of at least one lens. That is, the distance positioning device of the present invention has a function of simultaneously measuring the distance to the subject by using the autofocus function of the imaging camera for obtaining image data. This eliminates the need for a dedicated distance positioning device and provides a low-cost distance positioning device.

  Preferably, the distance calculation unit may calculate the distance to the subject based on the movement amount of the lens. The distance positioning device further includes a storage unit that stores a correspondence relationship between the lens position and the corresponding focal length, and the distance calculation unit calculates a distance to the subject from the correspondence relationship stored in the storage unit. May be.

  The distance positioning device further includes an identification unit that determines whether or not a specific object is included in the image data captured by the imaging camera, and the distance calculation unit can calculate the distance to the identified object. The distance measuring device further includes a determination unit that determines whether or not the distance to the identified specific object is smaller than a certain value, and further issues a warning when the distance is smaller than the certain value. be able to. The distance positioning device may further include an object information storage unit that stores information regarding a plurality of objects, and a selection unit that selects a specific object from the plurality of stored objects. In this case, a specific object may be selected in response to an instruction from the user.

  The navigation apparatus according to the present invention has a detecting means for detecting the position of the own vehicle by GPS or the like, and a correcting means for correcting the detected position of the own vehicle based on the distance from the distance positioning device. Since the position accuracy by GPS depends on the radio wave reception environment of the vehicle, the position accuracy sometimes deteriorates. In such a case, the vehicle position can be corrected with reference to the distance from the distance measuring device.

  According to the present invention, since the distance to the object (subject) is calculated using the autofocus technology mounted on the imaging camera, the object can be easily and inexpensively compared to the conventional case. Distance positioning can be realized. Thereby, the cost of the driving assistance system etc. of the vehicle carrying an imaging camera can be reduced. Further, in the navigation device, by using the distance measured by the distance positioning device, the position can be corrected when the position accuracy is deteriorated.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an in-vehicle distance measuring device according to an embodiment of the present invention. The distance positioning device 1 includes an imaging camera 10 mounted on the own vehicle, an image processing unit 12 that performs processing such as binarization of an image signal captured by the imaging camera 10, and generates image data. A display control unit 14 to be displayed on the display, a CPU 16 for controlling each unit, a memory 18 for storing data and programs for distance measurement, and an autofocus (AF) unit 20 for automatically focusing the imaging camera 10 on the subject. ing.

  The imaging camera 10 is attached to the front or rear of the host vehicle, and images the front field of view and the rear field of view of the host vehicle. The captured image data is used as display information for driving assistance to the driver. The attachment position and the number of attachments of the imaging camera are not particularly limited. You may image the circumference | surroundings of the own vehicle using a some imaging camera.

  What is characteristic in the distance measuring apparatus of the present embodiment is that the distance to the object can be measured using the autofocus function of the imaging camera. FIG. 2 is a diagram for explaining this feature in detail. The imaging camera 10 has a lens barrel 32 that can move in the axial direction Y of the cylinder 30, that is, the optical axis direction, in the cylinder 30, and a lens 34 is attached to the lens barrel 32. A plurality of lenses may be further included in the lens barrel 32, and the zoom function may be provided by adjusting the position of each of the plurality of lenses. A screw that engages with a screw formed on the inner wall of the cylinder 30 is formed on the outer wall of the lens barrel 32. By rotating the lens barrel 32 by a motor, the lens barrel 32 is moved in the optical axis direction Y. Can be moved freely. The lens barrel or the lens may be moved by other means.

  The AF unit 20 includes a drive circuit 40 for driving the lens barrel 32 in the optical axis direction Y, a focus detection unit 42 that detects whether the subject is in focus based on an image 36 of the subject by the lens 34, and a focus detection unit. A servo circuit 44 that controls the drive circuit 40 based on the detection signal 42 and a lens position detector 46 that detects the position of the lens 34 or the lens barrel 32 are provided. The focus detection unit 42 is configured using a known autofocus technique such as an active method, a contrast detection method, or a phase difference detection method.

  For example, when the subject A is imaged, the focus detection unit 42 detects whether or not the focal points are in agreement based on the image A1 of the subject A displayed on the image receiving image 36. Whether or not the focal points coincide with each other is determined, for example, for a fixed region at the center of the image receiving unit 36. If the focal points do not match, a detection signal indicating mismatch is output to the servo circuit 44. The servo circuit 44 adjusts the position of the lens or lens barrel 32 in the optical axis direction Y via the drive circuit 40. By such a servo function, the focal point of the lens 34 is matched with the subject A. When the focal points are matched, the lens position detection unit 46 outputs the position of the lens 34 or the position of the lens barrel 32 to the CPU 16. The position of the lens 34 may be an amount of movement from a certain reference position (for example, a position where the lens is most moved to one end by the drive circuit 40).

  Next, the distance positioning operation by the CPU 16 will be described with reference to the flow of FIG. When imaging of the field of view such as the front or rear of the vehicle is started by the imaging camera 10 (step S101), the AF unit 20 adjusts the focus of the imaging camera. The CPU 16 determines whether or not the focus on the subject coincides according to the detection signal of the focus detection unit 42 (step S102). When determining that the focal points coincide with each other, the CPU 16 receives the position or movement amount of the lens 34 through the detection signal of the lens position detection unit 46 (step S103).

  Next, the CPU 16 calculates the distance to the subject based on the position or movement amount of the lens 34 (step S104). As a calculation method, for example, the distance to the subject is calculated from the relational expression or approximate expression of the lens position and focal length, or, as shown in FIG. 4, the lens positions Z1, Z2,. , Fn may be stored in the memory 18 and the distance to the subject may be calculated from the corresponding relationship. In this case, the correspondence relationship between the movable range of the lens of the imaging camera and the range of the focal length that can be matched is set. The distance to the subject calculated in this way is displayed on the display by the display control unit 14 (step S105). In this case, the distance may be displayed over the captured image data.

  For example, as shown in FIG. 2, when the focus of the lens 34 matches the subject A, the CPU 16 calculates a distance D1 from the position of the lens 34 to the subject A. When the lens 34 is moved so that the focal point coincides with the subject B, the CPU 16 calculates a distance D2 from the position of the lens 34 to the subject B. As described above, when the autofocus from the subject A to the subject B is performed, the lens position detection 46 may detect the movement amount (difference) of the lens 34. The CPU 16 may calculate the distance D2 based on the previously calculated distance D1 to the subject A according to the movement amount. Further, the movement amount of the lens 34 may be obtained from the drive circuit 40 that drives the lens 34.

According to the distance measuring apparatus according to the present embodiment, since the autofocus technology of the imaging camera that images the surroundings of the vehicle is used, no special mechanism is required, and the object (object) can be very easily and at low cost. Can measure the distance. In addition, the lens of the imaging camera has the following characteristics.
(1) If the depth of field is shallow, the in-focus range is narrowed. That is, the distance positioning error is reduced and the accuracy is improved. The depth of field has a relationship as shown in FIG.
(2) The closer the distance to the subject, the narrower the in-focus range. That is, the distance positioning error is reduced and the accuracy is improved. This relationship is shown in FIG. (3) It is easier to focus if it is not too bright.
From the above, it is desirable that the conditions for reducing the positioning error satisfy that the object is on the front side on the telephoto side, that the aperture is on the open side, and that it is not too bright.

  Next, a second embodiment of the present invention will be described. In the second embodiment, an object in image data captured by an imaging camera is recognized, and an alarm is given when the recognized object approaches. FIG. 6 shows the operation flow.

  After the distance measurement to the subject is performed as in the first embodiment (steps S101 to S105), the CPU 16 determines whether the image processing unit 12 includes a specific object in the image data. Are identified (step S201). For example, the image processing unit 12 receives pattern data for a specific object from the memory 18 and identifies whether or not there is an object in the image data that matches the pattern data using an image processing technique. The pattern data can include, for example, data on the shape of a person, bicycle, car, etc., and information on color and contrast in addition to this. The memory 18 stores such a plurality of types of pattern data, and outputs predetermined pattern data based on an instruction from the CPU 16, which is given to the image processing unit 12. Which pattern data is to be selected may be preset, for example, or may be selected by the user.

  When the image processing unit 12 identifies a matching object, the result is transmitted to the CPU 16. The CPU 16 determines whether or not the distance to the identified object is smaller than a certain value (step S202). When the distance to the object is smaller than a certain value, the CPU 16 outputs an alarm by voice or the like from a speaker or the like (not shown), assuming that there is an object approaching the vehicle (step S203). In addition, an alarm may be displayed on the display by the display control unit 14.

  On the other hand, when the distance to the object exceeds a certain value, the CPU 16 monitors whether or not the distance to the identified object exceeds a certain value based on the output of the lens position detection unit 46, and from the certain value. When it becomes smaller, a warning is output.

  Next, a third embodiment of the present invention will be described. In the third embodiment, the distance positioning device of the first embodiment is applied to the correction of the vehicle position of the navigation device. FIG. 7 is a block diagram illustrating a configuration of the navigation device 100 according to the third embodiment. The GPS receiver 102 receives radio waves from GPS satellites and measures the current position and current direction of the vehicle. The self-contained navigation sensor 104 detects a vehicle speed sensor that detects a moving distance of the vehicle and a rotation angle of the vehicle. The user input interface 110 includes an operation panel 102, a voice input unit 104, and a remote control operation unit 106, and transmits these inputs to the control unit 130. The storage device 120 is preferably composed of a large-capacity hard disk (HD), and programs and databases for executing various navigation functions are stored in the hard disk. The database includes map data and facility data, and the map data includes road link data and intersection data. The control unit 130 displays map data around the vehicle position on the display 150, searches for a route to the destination, and outputs voice guidance from the speaker 140. Furthermore, the control unit 130 is connected to the distance positioning device 1 described above, and acquires image data captured by the imaging camera and distance information to the object.

  FIG. 8 is an operation flow when correcting the vehicle position. Here, correction of the vehicle position when performing route guidance will be described. The control unit 130 detects the vehicle position based on the output of the GPS receiver 102 and / or the autonomous navigation sensor 104, reads map data around the vehicle position from the recording device 120, and performs processing such as map matching. The vehicle position is displayed on the road (step S301).

  For example, as shown in FIG. 9, when the own vehicle 200 turns right at the next intersection K, the control unit 130 calculates a distance L to the intersection K based on the detected own vehicle position and map data (step S302). . When the distance L to the intersection reaches a certain value, for example, 700 meters before the intersection, the control unit 130 reads the intersection guidance information from the storage device 120 and performs guidance such as “turn right at the intersection 700 meters ahead”. (Step S303). At this time, the control unit 130 may display the image data captured by the imaging camera of the distance positioning device 1 on the display 150.

  Furthermore, using this guidance as a trigger, the control unit 130 instructs the distance positioning device 1 to measure the distance to the intersection (step S304). In response to this, the positioning distance device 1 determines whether or not an object capable of identifying the intersection is included in the image data obtained by the imaging camera. As information for identifying an intersection, for example, a pedestrian crossing or a traffic light can be used.

  As described in the second embodiment, when the object for identifying the intersection is included in the image data, the distance positioning device 1 measures the distance to the object, and the measured distance M is controlled by the control unit. It outputs to 130 (step S305). The control unit 130 compares the distance L to the intersection with the distance M measured by the distance positioning device 1, and if there is a certain difference (step S306), the detected vehicle position has an error. Determination is made (step S307). The detection accuracy of the vehicle position may be deteriorated due to the reception environment of radio waves such as GPS. For example, when there is a high-rise building B near the intersection K, it may be affected by multipath.

  When it is determined that there is an error, the control unit 130 corrects the vehicle position based on the distance M acquired by the distance positioning device 1 so that the difference becomes small (step S308). For example, if the distance M acquired by the distance positioning device 1 is 650 meters to the intersection K, the vehicle position is corrected to a position 650 meters from the intersection, and the mark position indicating the vehicle position on the display is also displayed. Correct it.

  When the distance to the intersection is calculated as L1 (L1 <L) as the host vehicle 200 approaches the intersection K, the control unit 130 again executes the intersection guidance, and the distance positioning device 1 performs the intersection K. An instruction is given to measure the distance M1 (M1 <M). The control unit 130 determines whether or not there is an error in the position of the own vehicle by the distance positioning device. Due to the characteristics of the imaging camera described above, the distance measuring device 1 measures the position as the own vehicle 200 approaches the intersection. The accuracy of the distance M1 is improved. Therefore, a certain difference for determining the error of the own vehicle position may be reduced. Thereby, the correction accuracy of the own vehicle position can be improved.

  As described above, when the accuracy of the vehicle position by the GPS receiver or the like in the navigation device deteriorates, the vehicle position can be easily corrected by referring to the distance information from the distance positioning device. In the above example, the vehicle position is corrected based on the intersection. However, the present invention is not limited to this, and it is also possible to correct the vehicle position based on another target.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific embodiments according to the present invention, and various modifications can be made within the scope of the gist of the present invention described in the claims. Deformation / change is possible.

  The distance positioning device according to the present invention can be used as a safe driving support system or a navigation device for a vehicle or the like. As a usage mode, it can be functionally coupled to an electronic device such as a navigation device or another computer.

It is a block diagram which shows the structure of the distance positioning apparatus which concerns on the Example of this invention. It is a figure explaining the characteristic of the distance positioning apparatus of a present Example. It is a figure explaining operation | movement of the distance positioning apparatus of a present Example. It is a table which shows the relationship between the position of a zoom lens, and the distance of a to-be-photographed object. It is a figure explaining the lens characteristic of an imaging camera. It is a figure which shows the operation | movement flow of the distance positioning apparatus which concerns on the 2nd Example of this invention. It is a block diagram which shows the structure of the navigation apparatus to which this invention is applied. It is an operation | movement flow explaining correction | amendment of the own vehicle position. It is a figure which shows the example of a correction | amendment of the own vehicle position.

Explanation of symbols

1: Distance positioning device 10: Imaging camera 12: Image processing unit 16: CPU
18: Memory 20: AF section 30: Cylinder 32: Lens barrel 34: Lens 40: Drive circuit 42: Focus detection section 44: Servo circuit 46: Lens position detection section

Claims (13)

A distance positioning device that measures the distance to an object using an in-vehicle imaging camera,
An imaging camera for imaging at least a part of the periphery of the vehicle;
Focus control means for adjusting the position of at least one lens so that the lens or lens group of the imaging camera is focused on the subject;
Distance calculating means for calculating the distance to the subject based on the position of at least one lens;
A distance positioning device. The distance positioning device according to claim 1, wherein the distance calculating unit calculates a distance to the subject based on a moving amount of the lens. The distance positioning device further includes storage means for storing the correspondence between the lens position and the corresponding focal length, and the distance calculation means calculates the distance to the subject from the correspondence stored in the storage means. Item 3. The distance measuring device according to Item 1. The distance positioning device further includes an identifying unit that identifies whether or not a specific object is included in the image data captured by the imaging camera, and the distance calculating unit calculates a distance to the identified object. Item 3. The distance measuring device according to Item 1. The distance positioning device according to claim 4, further comprising determination means for determining whether or not a distance to the identified specific object is smaller than a certain value. 6. The distance positioning device according to claim 5, further comprising warning means for issuing a warning when it is determined that the distance to the identified specific object is smaller than a certain value. The distance positioning device further includes object information storage means for storing information on a plurality of objects, and selection means for selecting a specific object from the plurality of stored objects. Distance positioning device. The distance positioning device according to claim 7, wherein the selection unit selects a specific object in response to an input from a user. A distance positioning device according to any one of claims 1 to 8,
A navigation device connected to the distance positioning device and receiving the image data and the distance from the distance positioning device to the specific object;
The navigation device corrects the vehicle position detected based on the distance from the detection means for detecting the vehicle position, the display means for displaying a map around the detected vehicle position on the display, and the distance measurement device. A navigation device having correction means. The distance positioning device according to claim 9, wherein the display means displays the image data obtained from the distance positioning device on a display. The correcting means has an error in the detected own vehicle position when the difference between the detected distance from the own vehicle position to the specific object and the distance to the specific object received from the distance measuring device is larger than a certain value. The navigation device according to claim 9, wherein the vehicle position is corrected as follows. A distance positioning method using an in-vehicle imaging camera equipped with an autofocus function,
Focusing the lens of the imaging camera on the subject and displaying the captured image data on a display;
Calculating the distance to the subject based on the position or amount of movement of the lens;
A distance positioning method. The distance positioning method according to claim 12, further comprising a step of outputting a warning when the distance to the subject is smaller than a certain value.

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