JP4882592B2 - Light extraction apparatus, light extraction method, and distance measurement system - Google Patents

Description

  The present invention relates to a light extraction device, a light extraction method, and a distance measurement system that can extract light (irradiation light) applied to a distance measurement object even when the brightness of background light such as sunlight changes.

  Conventionally, many devices have been proposed that irradiate a distance measuring object, receive reflected light from the distance measuring object, and detect the distance to the distance measuring object based on the received light. (For example, refer to Patent Document 1).

In the apparatus of Patent Document 1, stationary light is detected before light (irradiation light) is irradiated (projected) toward a distance measurement object, and the distance measurement object is irradiated with light. By removing the component corresponding to the stationary light from the received light signal when the reflected light from the light is received, the light (irradiated light) irradiated to the distance measuring object is extracted.
JP-A-5-172656

  By the way, when receiving reflected light from a distance measurement object by irradiating light (irradiation light) as in the apparatus of Patent Document 1, background light (steady light) such as sunlight with respect to the distance measurement object. If the brightness (brightness) of the object to be measured changes due to a change in the brightness of the object, it may be erroneously determined that the change in brightness is due to irradiation light. As described above, when the brightness of background light such as sunlight changes, it becomes impossible to accurately extract light (irradiation light) applied to the distance measuring object.

  Therefore, the present invention provides light (irradiated light) irradiated to a distance measurement object even when the brightness of the distance measurement object changes due to a change in the brightness of background light such as sunlight with respect to the distance measurement object. It is an object to provide a light extraction device, a light extraction method, and a distance measurement system that can accurately extract the above.

In order to achieve the above object, a light extraction apparatus according to the present invention includes an irradiating unit that irradiates irradiation light corresponding to at least different first and second wavelengths toward a predetermined direction in a switchable manner; Imaging means for imaging a direction in a wavelength region including at least the first wavelength and the second wavelength, and a ranging object extraction means for extracting a ranging object from an image captured by the imaging means; wherein when not irradiated with irradiation light from the irradiation means, the image of the measuring object extracted by the range-finding object extraction unit, wherein the first wavelength and the second of each luminance of the wavelength in the whole image values, and the wavelength between information calculation means and the first wavelength to calculate a ratio of luminance values between the second wavelength, on the basis of the respective luminance value calculated by the inter-wavelength-information obtaining means, the luminance value Is smaller than the second wavelength Sets the serial first wavelength illumination wavelength of the illumination light irradiated from the irradiation unit, and wavelength setting means that the brightness value is set to the second wavelength is greater than said first wavelength in a non-illumination wavelength, The first wavelength and the second wavelength from the image of the distance measuring object imaged by the imaging unit when the irradiation light of the irradiation wavelength set by the wavelength setting unit is irradiated from the irradiation unit. Wavelength conversion means for converting the image into the first image, the first wavelength calculated by the inter-wavelength information calculation means and the first wavelength from the images of the first wavelength and the second wavelength converted by the wavelength conversion means. based on the ratio of luminance values between 2 wavelengths, calculating the luminance value of the irradiation wavelength corresponding to the luminance value of the non-irradiation wavelength set by the wavelength setting means definitive when irradiated with irradiation light from the irradiation unit and, it calculated the irradiated Based on the difference between the luminance value of the irradiation wavelength at the time of irradiation Luminance value of the length and the irradiation light, the irradiation light extracting means for extracting the irradiation light irradiated on the range-finding object from said irradiation means, It is characterized by having.

Further, the light extraction method according to the present invention includes a first step of irradiating irradiation light corresponding to at least different first and second wavelengths at least in a predetermined direction from an irradiation unit, and the predetermined direction. A second step of picking up a distance measurement object from an image picked up by the image pick-up means, a second step of picking up an image in a wavelength region including at least the first wavelength and the second wavelength, wherein when the illumination means is not irradiated with the irradiation light, wherein the image of the third the distance measuring object extracted in step, the luminance value of the said in the entire image the first wavelength the second wavelength, and A fourth step of calculating a ratio of luminance values between the first wavelength and the second wavelength, and a luminance value based on the respective luminance values calculated in the fourth step from the second wavelength. The first is also small Sets the wavelength irradiation wavelength of the irradiation light irradiated from the irradiation unit, and a fifth step in which the luminance value is set to the second wavelength is greater than said first wavelength in a non-illumination wavelength, said fifth step When the irradiation light having the irradiation wavelength set in step S3 is irradiated from the irradiation unit, the image of the distance measuring object imaged by the imaging unit is converted into an image of the first wavelength and the second wavelength. 6 and step, the first six said converted from the first wavelength in step second wavelength images, luminance between said fourth said first wavelength calculated in step the second wavelength based on the ratio value, said calculating a luminance values of irradiation wavelength corresponding to the luminance value of the non-irradiation wavelength set by the fifth step of definitive when irradiated with irradiation light from the irradiation means, the calculated the irradiated and bright degree value of the wavelength And a seventh step of extracting irradiation light irradiated on the distance measuring object from the irradiation means based on a difference from the luminance value of the irradiation wavelength when the irradiation light is irradiated. .

The distance measuring system according to the present invention, according to claim 1 and a light extraction device according to any one of乃Itaru 3, information of the irradiation light irradiated on the measuring object extracted by the light extracting device And distance calculation means for calculating a distance to the distance measurement object by a triangulation method based on positional relationship information between the imaging means and the irradiation means.

  According to the light extraction device and the light extraction method according to the present invention, in an environment in which the brightness changes with the passage of time due to background light (light such as direct sunlight or non-direct light from clouds or shielding objects). In addition, it is possible to accurately extract the irradiation light applied to the distance measuring object. Moreover, according to the distance measurement system which concerns on this invention, the distance to a ranging object can be calculated accurately based on the information of the irradiation light extracted accurately by the light extraction apparatus.

  Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 is a block diagram illustrating a configuration of a distance measurement system including a light extraction device according to an embodiment of the present invention. The distance measurement system according to the present embodiment is mounted on a vehicle (automobile) and is applied to a distance measurement system that measures a distance (inter-vehicle distance) from a preceding vehicle.

  As shown in FIG. 1, the distance measurement system 1 according to this embodiment includes a light extraction device 2. The light extraction device 2 includes a camera 3 that images the front road surface side of the host vehicle as a moving body on which the distance measurement system 1 is mounted, a memory 4 that stores image data captured by the camera 3, and the host vehicle. Irradiation device 5 for irradiating light toward the front road surface side of the vehicle, and irradiation control for performing control to switch the wavelength of light irradiated from the irradiation device 5 (hereinafter referred to as irradiation light) to one of two specific wavelengths The unit 6 and the preceding vehicle extraction unit 8 and the light extraction unit 9 in the control unit 7 are provided as main components.

  Further, in the control unit 7, a distance calculation unit 10 that calculates a distance (inter-vehicle distance) with the preceding vehicle A as a distance measurement object based on irradiation light extraction information from the light extraction unit 9 described later. The alarm unit 11 outputs an alarm signal to the buzzer 12 or the like when the distance to the preceding vehicle A calculated by the distance calculation unit 10 is a predetermined distance or less. The control unit 7 is constituted by a microprocessor that performs calculation, a ROM that stores a program for causing the microprocessor to execute predetermined processing, a RAM that stores various data such as calculation results, and the like. .

  In this embodiment, as shown in FIG. 2, the camera 3 is installed in the vicinity of the upper part of the front window 14 in the passenger compartment of the host vehicle 13 on which the distance measuring system 1 is mounted. The camera 3 is a video camera in which an imaging element such as a CCD and a lens, a filter, and the like are combined in a housing, and outputs a color image in a predetermined wavelength region (visible light region in the present embodiment) sequentially captured in time series. .

  In this embodiment, as shown in FIG. 2, the irradiation device 5 is also used as a headlight on one side (left side in the figure) installed in the host vehicle 13. The headlight as the irradiation device 5 in the present embodiment can select and irradiate spot light of two specific wavelengths (in this embodiment, wavelengths corresponding to red (R) and blue (B), respectively). LED is used as a light source. In addition, the headlight (irradiation device 5) using this LED as a light source can irradiate light having a normal brightness as a headlight with a predetermined orientation pattern, and is used as a normal headlight at night or the like. You can irradiate daylight light.

  The preceding vehicle extraction unit 8 in the control unit 7 performs a pattern matching process between an image captured by the camera 3 read from the memory 4 and a preset preceding vehicle pattern from the image captured by the camera 3 in front of the host vehicle. The preceding vehicle that is driving is extracted.

  The light extraction unit 9 in the control unit 7 includes an inter-wavelength information calculation unit 15, a wavelength setting unit 16, a wavelength conversion unit 17, and an irradiation light extraction unit 18.

  The inter-wavelength information calculation unit 15 obtains a different first wavelength from the image of the preceding vehicle A captured by the camera 3 before irradiating the irradiation light a from the headlight as the irradiation device 5 (non-irradiation). In the embodiment, each luminance value of a wavelength component corresponding to blue) and a second wavelength component (a wavelength corresponding to red in this embodiment), and a luminance value between the first wavelength and the second wavelength. The ratio is calculated.

  The wavelength setting unit 16 sets the wavelength with the smaller luminance value calculated by the inter-wavelength information calculation unit 15 (in this embodiment, the first wavelength) as the irradiation wavelength, and the luminance calculated by the inter-wavelength information calculation unit 15 The wavelength having the larger value (in this embodiment, the second wavelength) is set as the non-irradiation wavelength (hereinafter referred to as background calculation wavelength). The irradiation control unit 6 switches and controls the irradiation wavelength set by the wavelength setting unit 16 and irradiates the irradiation device 5 with the irradiation light a having the irradiation wavelength. In addition, since the background calculation wavelength has a large luminance value, the luminance value is excellent in response to a slight change in the brightness of the background light (light such as direct sunlight, non-direct light from clouds, shields, etc.). Can be calculated.

  The wavelength conversion unit 17 irradiates from the image of the preceding vehicle A captured by the camera 3 when the irradiation device 5 (headlight) irradiates the irradiation light a (light having the irradiation wavelength set by the wavelength setting unit 16). It converts into the image of a wavelength component and a background calculation wavelength component.

  The irradiation light extraction unit 18 is a luminance value between the first wavelength (irradiation wavelength in the present embodiment) calculated by the inter-wavelength information calculation unit 15 and the second wavelength (background calculation wavelength in the present embodiment). Based on the ratio, the luminance value for the irradiation wavelength corresponding to the luminance value of the background calculation wavelength is calculated, and the difference between the calculated luminance value for the irradiation wavelength and the luminance value of the irradiation wavelength measured when the irradiation light a is irradiated Based on the above, the irradiation light a irradiated from the irradiation device 5 is extracted (details will be described later).

  Next, a method for extracting irradiation light by the light extraction device 2 of the distance measurement system 1 according to the present embodiment will be described with reference to a flowchart shown in FIG. In this case, in the extraction processing operation of the irradiation light by the light extraction device 2, the brightness changes with the passage of time due to background light (light such as direct sunlight or non-direct light from clouds, shields, etc.). This is the case of daytime (daytime).

  First, extraction processing of a preceding vehicle traveling in front of the host vehicle equipped with the distance measuring system 1 is performed (step S1). Here, the preceding vehicle extraction process will be described with reference to the flowchart shown in FIG.

  The camera 3 installed near the upper part of the front window 14 in the passenger compartment of the host vehicle 13 (see FIG. 2) images the front side of the running road surface (step S11). The captured images sequentially captured in time series by the camera 3 are stored in the memory 4 as digital image information (step S12). Then, the preceding vehicle extraction unit 8 in the control unit 7 takes in the image read from the memory 4 and performs a pattern matching process based on a preset preceding vehicle pattern and a normalized correlation process (step S13).

  Then, by this pattern matching processing, a vehicle whose correlation value exceeds a predetermined value is extracted as a preceding vehicle (step S14: YES), and the image area of the preceding vehicle in the image captured by the camera 3 and the direction of the preceding vehicle viewed from the camera 3 Is calculated as a feature amount (step S15), and the preceding vehicle extraction process is terminated. If the preceding vehicle cannot be extracted in step S14 (step S14: NO), the process returns to step S11 and the above-described process is repeated.

  When the preceding vehicle A (see FIG. 1) is extracted from the image captured by the camera 3 by the preceding vehicle extraction unit 8 in the preceding vehicle extraction process in step S1, the spot is firstly extracted from the irradiation device 5. Before irradiating the preceding vehicle A with the light irradiation light a (when not irradiating), the image of the preceding vehicle A captured by the camera 3 is changed to a different first wavelength (in this embodiment, blue (B)). (Corresponding wavelength) and the second wavelength (in this embodiment, the wavelength corresponding to red (R)) is measured (step S2), between the first wavelength and the second wavelength A ratio of luminance values is calculated (step S3).

  That is, before irradiating the preceding vehicle A with the irradiation light a from the irradiation device 5 (when not irradiating), red (R) and blue (B) in the entire image area of the preceding vehicle A measured by the inter-wavelength information calculation unit 15. ) For each wavelength, for example, as shown in FIG. 5A, the wavelength setting unit 16 uses the first wavelength with the smaller luminance value calculated by the inter-wavelength information calculation unit 15. (Wavelength corresponding to blue (B)) is set as the irradiation wavelength, and the second wavelength (wavelength corresponding to red (R)) having the larger luminance value calculated by the inter-wavelength information calculation unit 15 is set as the background calculation wavelength. It is set as (non-irradiation wavelength) (step S4).

  In the present embodiment, based on the result shown in FIG. 5A, the ratio of luminance values between the background calculation wavelength (wavelength corresponding to red (R)) and the irradiation wavelength (wavelength corresponding to blue (B)). (R / B) is calculated. After that, the irradiation control unit 6 controls to switch to the irradiation wavelength set in step S4, and irradiates the irradiation light 5 in the form of spot light having the irradiation wavelength toward the preceding vehicle A from the irradiation device 5 (step S5).

  Then, from the image of the preceding vehicle A captured by the camera 3 when the irradiation light 5 is irradiated from the irradiation device 5 (headlight), the wavelength conversion unit 17 applies the irradiation wavelength (wavelength corresponding to blue (B)) and After conversion into an image of the background calculation wavelength (wavelength corresponding to red (R)), based on the converted image, the inter-wavelength information calculation unit 15 converts the irradiation wavelength (blue (B) in the entire image region of the preceding vehicle A to The luminance values of the corresponding wavelength) and the background calculation wavelength (the wavelength corresponding to red (R)) are measured (step S6).

  FIG. 5 (b) shows the entire image area of the preceding vehicle A measured in step S6 when the preceding vehicle A is irradiated with the irradiation light a of the irradiation wavelength (wavelength corresponding to blue (B)) from the irradiation device 5. It is a figure which shows an example of the brightness | luminance (brightness) with respect to an irradiation wavelength (wavelength corresponding to blue (B)) and a background calculation wavelength (wavelength corresponding to red (R)). In FIG. 5 (b), the brightness of the background light with respect to the preceding vehicle A changes over time from the non-irradiation time of FIG. 5 (a), and the non-irradiation time of FIG. It changes so that the brightness | luminance of background calculation wavelength (wavelength corresponding to red (R)) becomes large.

Then, based on the ratio (R / B) of the luminance value between the background calculated wavelength (wavelength corresponding to red (R)) calculated in step S3 and the irradiation wavelength (wavelength corresponding to blue (B)), step S6 is performed. the luminance value of the irradiation wavelength corresponding to the luminance value of the background calculated wavelength calculated by the irradiation light extractor 18 at (step S7), and the calculated illumination wavelength measured brightness value and the irradiation light a the irradiation wavelength upon irradiation Based on the difference from the luminance value, the irradiation light a irradiated from the irradiation device 5 is extracted (step S8).

That is, as shown in FIG. 5C, the difference (= B−H) between the luminance value B of the irradiation wavelength measured when the irradiation light a is irradiated and the luminance value H of the irradiation wavelength calculated in step S7. When the difference is equal to or greater than a preset threshold, the calculated difference is extracted as the irradiation light a irradiated from the irradiation device 5.

  In this way, the information (irradiation light signal) of the irradiation light a extracted by the irradiation light extraction unit 18 is input to the distance calculation unit 10 in the control unit 7. The distance calculation unit 10 geometrically converts the pixels from which the irradiation light a in the entire image area of the preceding vehicle A is extracted, and determines the direction of the irradiation light a irradiated to the preceding vehicle A viewed from the camera 3. Based on the calculated direction information, the irradiation direction information of the irradiation light a irradiated from the irradiation device 5 to the preceding vehicle A, and the preset positional relationship information between the camera 3 and the irradiation device 5 The distance to the preceding vehicle A is calculated by the triangulation method.

  When it is determined that the calculated distance to the preceding vehicle A is equal to or less than the preset distance, that is, when it is determined that the host vehicle is approaching the preceding vehicle A, the distance calculating unit 10 11 outputs a signal. Based on the signal input from the distance calculation unit 10, the alarm unit 11 outputs an alarm signal to the buzzer 12 to make an alarm sound or blink (or light) a warning light (not shown). This can warn the driver that the host vehicle is approaching the preceding vehicle A.

  Thus, according to the light extraction device 2 according to the present embodiment, the environment in which the brightness changes with the passage of time due to background light (light such as direct sunlight, non-direct light from clouds, shielding objects, etc.). Even underneath, the irradiation light a irradiated to the preceding vehicle A can be extracted with high accuracy. Thereby, the distance measurement system 1 according to the present embodiment can calculate the distance to the preceding vehicle A with high accuracy based on the information of the irradiation light a extracted with high accuracy by the light extraction device 2.

  In the above-described embodiment, the headlight is used as the irradiation device. However, in addition to this, for example, as shown in FIG. A dedicated irradiation device 5a having a light source such as an LED that can irradiate a spot light that can be switched to two wavelengths (in this embodiment, each wavelength corresponding to red (R) and blue (B), respectively) is installed. Also good.

  In the embodiment described above, the wavelength of the irradiation light irradiated from the irradiation device 5 (5a) can be switched to each wavelength corresponding to red (R) and blue (B). The configuration may be such that any two wavelengths of red (R), green (G), and blue (B) are switched.

  In the above-described embodiment, the present invention has been described as an example of a distance measurement system mounted on a vehicle (automobile) that measures the distance between the preceding vehicles (inter-vehicle distance), but is not limited thereto. The present invention can be similarly applied to a distance measurement system that measures a distance to an arbitrary distance measurement object.

The block diagram which shows the structure of the distance measurement system provided with the light extraction apparatus which concerns on embodiment of this invention. The perspective view which shows the vehicle which installed the camera and irradiation apparatus of the light extraction apparatus which concern on embodiment of this invention. The flowchart which shows the extraction method of the irradiation light by the light extraction apparatus which concerns on embodiment of this invention. The flowchart which shows the extraction process of the preceding vehicle in the preceding vehicle extraction part in embodiment of this invention. (A) is a figure which shows an example of the brightness | luminance with respect to each wavelength of red and blue in the preceding vehicle imaged at the time of non-irradiation, (b) is an example of the brightness | luminance with respect to each wavelength of red and blue in the preceding vehicle imaged at the time of irradiation. The figure which shows, (c) is a figure which shows the condition which extracted irradiation light from the difference of the luminance value of the irradiation wavelength measured when irradiated with irradiation light, and the luminance value with respect to the irradiation wavelength according to the luminance value of a background calculation wavelength . The perspective view which shows the vehicle which installed the irradiation apparatus of the light extraction apparatus which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Distance measuring system 2 Light extraction device 3 Camera (imaging means)
4 Memory 5, 5a Irradiation device (irradiation means)
6 Irradiation control unit 7 Control unit 8 Leading vehicle extraction unit (ranging object extraction means)
9 Light extraction part 10 Distance calculation part (distance calculation means)
DESCRIPTION OF SYMBOLS 11 Warning part 12 Buzzer 13 Own vehicle 15 Inter-wavelength information calculation part (Inter-wavelength information calculation means)
16 Wavelength setting unit (wavelength setting means)
17 Wavelength conversion part (wavelength conversion means)
18 Irradiation light extraction unit (irradiation light extraction means)
A preceding vehicle (object for distance measurement)

Claims (5)

Irradiating means for irradiating the irradiation light respectively corresponding to at least different first and second wavelengths at least in a predetermined direction;
Imaging means for imaging the predetermined direction in a wavelength region including at least the first wavelength and the second wavelength;
Ranging object extraction means for extracting a ranging object from the image captured by the imaging means;
Wherein when not irradiated with irradiation light from the irradiation means, the image of the measuring object extracted by the range-finding object extraction unit, wherein the first wavelength and the second of each luminance of the wavelength in the whole image An inter-wavelength information calculating means for calculating a value and a ratio of a luminance value between the first wavelength and the second wavelength;
Based on the respective luminance values calculated by the inter-wavelength information calculating means, the first wavelength whose luminance value is smaller than the second wavelength is set as the irradiation wavelength of the irradiation light emitted from the irradiation means. Wavelength setting means for setting the second wavelength having a luminance value larger than the first wavelength as a non-irradiation wavelength;
The first wavelength and the second wavelength from the image of the distance measuring object imaged by the imaging unit when the irradiation light of the irradiation wavelength set by the wavelength setting unit is irradiated from the irradiation unit. Wavelength converting means for converting into an image of
From the images of the first wavelength and the second wavelength converted by the wavelength conversion means, the ratio of the luminance value between the first wavelength and the second wavelength calculated by the inter-wavelength information calculation means based on the above-calculated luminance values of irradiation wavelength corresponding from the irradiation means to the luminance value of the non-irradiation wavelength set by the wavelength setting means definitive when irradiated with irradiation light, calculated brightness of the irradiation wavelength Irradiation light extraction means for extracting the irradiation light irradiated to the distance measuring object from the irradiation means based on the difference between the value and the luminance value of the irradiation wavelength when the irradiation light is irradiated,
The light extraction apparatus characterized by the above-mentioned. The first wavelength and the second wavelength are different wavelengths selected from red, green, and blue wavelengths.
The light extraction device according to claim 1. The irradiating means uses an LED capable of irradiating spot-like irradiation light as a light source,
Light extraction device according to claim 1 or 2, characterized in that. A first step of irradiating irradiation light corresponding to each of at least different first and second wavelengths from the irradiation means in a switchable manner in a predetermined direction;
A second step of imaging the predetermined direction by an imaging means in a wavelength region including at least the first wavelength and the second wavelength;
A third step of extracting a ranging object from the image captured by the imaging means;
Wherein when the illumination means is not irradiated with the irradiation light, wherein the image of the third the distance measuring object extracted in step, the luminance value of the said in the entire image the first wavelength the second wavelength, and A fourth step of calculating a ratio of luminance values between the first wavelength and the second wavelength;
Based on the respective luminance values calculated in the fourth step, the first wavelength whose luminance value is smaller than the second wavelength is set to the irradiation wavelength of the irradiation light irradiated from the irradiation means, and the luminance A fifth step of setting the second wavelength having a value larger than the first wavelength as a non-irradiation wavelength;
The first wavelength and the second wavelength from the image of the distance measuring object imaged by the imaging means when the irradiation light of the irradiation wavelength set in the fifth step is emitted from the irradiation means. A sixth step of converting to an image of
Based on the ratio of the luminance value between the first wavelength and the second wavelength calculated in the fourth step from the images of the first wavelength and the second wavelength converted in the sixth step. , calculates the luminance value of the irradiation wavelength corresponding to the luminance value of the non-irradiation wavelength set by definitive the fifth step when irradiated with irradiation light from the irradiation unit, and luminance values of the calculated the illumination wavelength A seventh step of extracting irradiation light irradiated to the distance measuring object from the irradiation means based on a difference from a luminance value of the irradiation wavelength when the irradiation light is irradiated;
The light extraction method characterized by the above-mentioned. A light extraction device according to any one of claims 1乃Itaru 3,
Based on the information of the irradiation light irradiated on the distance measurement object extracted by the light extraction device and the positional relationship information between the imaging means and the irradiation means, the distance measurement object is obtained by triangulation. A distance calculating means for calculating the distance,
A distance measurement system characterized by this.

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