JP4019182B2 - Visual equipment - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a visual device that recognizes an imaging region from an image captured by a camera.
[0002]
[Prior art]
Conventionally, a video camera is mounted on a vehicle, a front area is imaged by the video camera, and an obstacle is recognized from the captured image (see JP-A-6-215300).
[0003]
However, with a video camera, it is not possible to image the front area even when the vehicle headlight is turned on, such as in fog.
[0004]
That is, for example, as shown in FIG. 8, a front area is illuminated by a headlight 4 having a relatively wide opening angle 6 of illumination light LL, and reflected light RL from the illumination area is received by a video camera 2 for illumination. When imaging an area, if an aerosol Z such as fog, smoke, or dust is present in the illumination area, the illumination light LL is scattered by the aerosol Z and travels toward the light receiving portion of the video camera 2 in the scattered light. The light N is received by the video camera 2 as noise. Further, a part of the illumination light LL that has passed through the aerosol Z irradiates the object 3 in the illumination area, but the reflected light RL is further scattered and attenuated by the aerosol Z, and only a small amount of the reflected light RL is emitted. No light is received by the video camera 2.
[0005]
Therefore, as the amount of the aerosol Z in the illumination area increases, noise increases, the amount of reflected light RL received from the illumination area decreases, and even if the light intensity of the illumination light LL is increased, the video camera 2 It becomes difficult to make an image.
[0006]
Conventionally, an infrared camera is mounted on a vehicle, the front area is imaged by the infrared camera, and an obstacle is recognized from the captured image (see Japanese Patent Laid-Open No. 54-92117).
[0007]
However, with infrared cameras, it is possible to recognize objects with a large amount of infrared radiation, such as humans and automobiles, even at night or in fog. A road surface or road structure with a small amount cannot be clearly recognized, and it is particularly difficult to recognize a white line on the road.
[0008]
[Problems to be solved by the invention]
The problem to be solved is that a visual device using a conventional video camera cannot image the front area in an aerosol such as fog, smoke, and dust. In addition, a visual device using an infrared camera cannot recognize an object with a small amount of infrared radiation.
[0009]
[Means for Solving the Problems]
The present invention uses an illumination light source so that a good captured image can be obtained even in an aerosol such as fog, smoke, dust, etc., when a front area of the vehicle is imaged by a camera mounted on the vehicle . A first camera for imaging a road surface that images an illuminated area, and a second camera for imaging an obstacle that images the same in a wavelength band having a sensitivity different from that of the first camera. respectively so as to take the resulting Ru means a composite image of an image captured by and the second of each camera.
[0010]
At that time, in the present invention, in particular, the first camera having sensitivity in the visible light or near infrared frequency band is used, and then the opening angle of the illumination light emitted from the illumination light source and the first camera The illumination light source and the first light source are arranged so that the viewing angle of one pixel is smaller than the angle between the optical axis of the illumination light and the optical axis of the reflected light from the object irradiated with the illumination light to the first camera. Reflective light with high S / N ratio against scattering noise caused by aerosol by the first camera even if it is in aerosol such as fog, smoke, dust, etc. So that the illumination area can be imaged.
[0011]
Using a second camera that shows sensitivity in the infrared frequency band around 10 μm , it recognizes obstacles such as humans and automobiles that emit infrared rays even in aerosols such as fog, smoke, and dust. Can be performed clearly over a relatively wide range.
[0012]
【Example】
FIG. 5 shows a simulation model for measuring the S / N ratio of the reflected light RL when the opening angle θ ₁ of the illumination light LL is variously changed while the installation distance D between the illumination light source 1 and the video camera 2 is variable. In the mist in which the transmittance of the illumination light LL by visible light is reduced to about 5% at L = 50 m ahead, the reflected light RL from the object 3 having a reflectance of 1 placed 50 m ahead is reflected by the video camera 2. It is designed to receive light.
[0013]
FIG. 6 shows the characteristics of the simulation result at that time. In the characteristic diagram, the horizontal axis represents the installation interval D between the illumination light source 1 and the video camera 2, and the vertical axis represents the SN ratio. Further, as the opening angle θ ₁ of the illumination light LL, parameters of 0.5 mrad (milliFradian), lmrad, 5 mrad, 17 mrad, and 85 mrad are taken.
[0014]
From this simulation result, it can be seen that the SN ratio is improved as the opening angle θ ₁ of the illumination light LL emitted from the illumination light source ₁ is decreased. This is the same even if the opening angle (viewing angle) θ ₂ of light reception of one pixel in the video camera ₂ is reduced. It can also be seen that the S / N ratio is improved as the installation distance D between the illumination light source 1 and the video camera 2 is increased.
[0015]
This reduces the viewing angle theta ₂ at an angle theta ₁ or the video camera 2 opening of the illumination light LL, also, increasing the installation distance D between the illumination light source 1 and the optical sensor 2, the illumination light LL Since the size of the overlapping region C of the illumination region A and the reflection region B of the reflected light RL is reduced, and the amount of noise light toward the light receiving unit of the video camera 2 when the illumination light LL is scattered by fog is suppressed. it is conceivable that.
[0016]
As the illumination light LL emitted from the illumination light source 1, it is conceivable to use infrared rays having good transparency in aerosols such as fog, smoke, and dust. However, visible light or near infrared rays are used for the following reasons. It is appropriate to use.
[0017]
That is, when the illumination light source 1 and the video camera 2 are mounted on a vehicle to image a road ahead, sufficient reflected light from the object can be obtained even when the illumination light LL is obliquely applied to the object. Therefore, it is preferable to use illumination light having a wavelength smaller than the unevenness of the surface of the object, and visible light or near infrared light having a shorter wavelength than infrared light is more suitable.
[0018]
FIG. 7 is a characteristic diagram when the transmittance of electromagnetic waves in an artificial mist with the average particle diameter changed in the range of 1 to 10 μm is measured under the same conditions. It turns out that the transmittance | permeability of the infrared rays before and behind (the range of 5-20 micrometers) is high.
[0019]
The object itself radiates electromagnetic waves, and it is known that infrared rays around 10 μm are radiated most at room temperature.
[0020]
Therefore, if an infrared camera showing sensitivity in a frequency band around 10 μm is used, an object can be imaged even in an aerosol such as fog, smoke, dust, etc. This makes it possible to recognize an object that has a higher temperature and a greater amount of infrared radiation than an automobile or the like.
[0021]
FIG. 1 shows an embodiment of a visual device according to the present invention configured in consideration of the above examination results. Here, the visual device is mounted on a vehicle and fog, smoke, dust, etc. Even in the aerosol, the video camera 2 can be used to image a road illumination area in front of the vehicle with the illumination light source 1, and the infrared camera 5 can be used to obstruct humans or automobiles existing in the vehicle front area. An object is imaged over a wide range, and each captured image is synthesized by an image synthesizer (not shown).
[0022]
The illumination light source 1 and the video camera 2 are illuminations in which the opening angle θ of the illumination light LL in the illumination light source 1 and the viewing angle θ of the video camera 2 illuminate the front road surface 8 in the vertical direction of the front portion of the vehicle 7. They are arranged with a relationship (θ, θ <α) that is smaller than an angle α formed by the optical axis of the light LL and the optical axis of the reflected light RL from the road surface 8.
[0023]
Thus, by arranging the illumination light source 1 and the video camera 2 in the front part of the vehicle 7 so as to satisfy the relationship of θ ₁ , θ ₂ <α, aerosols such as fog, smoke, and dust in the illumination area. Even when the illumination light LL is scattered by the aerosol, the video camera 2 can receive the reflected light RL having a high SN ratio in which the amount of noise directed to the light receiving unit of the video camera 2 is minimized. As a result, it becomes possible to effectively capture the road surface 8 in front of the vehicle.
[0024]
At this time, for example, the illumination light source 1 and the video camera 2 are set so that the road surface 8 can be illuminated a few meters ahead of the vehicle 7 in order to ensure the minimum forward visibility when traveling in fog. In order to be able to image the road surface 8 with a sufficient width, the illumination light source 1 has an aperture that allows the illumination light LL emitted therefrom to spread in the left-right direction, and the light receiving unit of the video camera 2 is also provided. Similarly, the left and right sides are expanded.
[0025]
FIG. 2 shows an example of an image captured on the road surface 8 by the video camera 2 when the illumination light source 1 and the video camera 2 are attached to the front portion of the vehicle 7 in this manner. The road edge and the white line 9 of the center line are clearly imaged.
[0026]
At this time, the front road surface 8 that is visible by turning on the headlight 4 of the vehicle 7 can be simultaneously imaged by the video camera 2.
[0027]
A portion that is neither illuminated by the illumination light source 1 nor the headlight 4 is predicted from both data. Further, data can be increased by scanning the illumination light source 1 for a plurality of lines instead of one line.
[0028]
Moreover, the infrared camera 5 is installed in the front part of the vehicle 7 so that the front area | region of a vehicle can be imaged over a wide range.
[0029]
FIG. 3 shows an example of an image captured by the infrared camera 5. Here, a person 10 outside the illumination area of the illumination light source 1 in front of the vehicle is clearly imaged.
[0030]
Thus, even when the vehicle 7 is traveling in fog or the like, the image synthesized by the video camera 2 and the image taken by the infrared camera 5 are synthesized by an image synthesizer, as shown in FIG. An actual image can be obtained in which the road surface 8 in front of the vehicle illuminated by the light source 1 and the person 10 outside the illumination area are integrated.
[0031]
Then, if the composite image is projected on the windshield side of the driver's seat using, for example, a head-up display, the driver will be able to And it is possible to recognize that there are obstacles such as humans and automobiles ahead.
[0032]
It is also possible to provide the automatic traveling device with the data of the composite image so as to perform control so as to automatically travel on the road while avoiding obstacles.
[0033]
Furthermore, it goes without saying that the present invention is not limited to being mounted on a vehicle but is widely used as a visual device for an automatic traveling robot, a general visual device for monitoring, and the like.
[0034]
【effect】
As described above, according to the visual device of the present invention, the illumination light source that is installed in the upper part of the vehicle and illuminates the front area of the vehicle, and the area that is installed below the illumination light source in the vehicle and illuminated by the light source A first camera for road surface imaging showing sensitivity in a visible light or near infrared frequency band to be imaged, and a sensitivity in an infrared frequency band around 10 μm which is installed in a vehicle and images the same as the first camera. Illumination light emitted from an illumination light source, comprising a second camera for imaging an obstacle such as a human being that emits infrared rays, and means for obtaining a composite image of the images respectively captured by the first and second cameras And a light source for illumination having a relationship such that the opening angle of the light source and the viewing angle of the first camera are smaller than the angle formed by the optical axis of the illumination light and the optical axis of the reflected light from the illumination region to the first camera First By disposing the camera, to obtain a clear captured image actually conformity according to obstacles such as a human even in the aerosol not hear the visibility present in the road surface and its front region in front of the vehicle It can, be so that it is possible to ensure the driving view field.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a visual device according to the present invention.
FIG. 2 is a diagram illustrating an example of an image obtained by capturing an illumination area of an illumination light source with a video camera in the embodiment.
FIG. 3 is a diagram showing an example of an image captured by an infrared camera in the same embodiment.
FIG. 4 is a diagram illustrating an example of an image obtained by combining an image captured by a video camera and an image captured by an infrared camera.
FIG. 5 is a schematic configuration diagram of a simulation model for measuring an S / N ratio of reflected light when an illumination area by an illumination light source is imaged by a video camera.
FIG. 6 is a characteristic diagram of a simulation result in which the opening angle of illumination light is a parameter, the horizontal axis is the distance between the illumination light source and the video camera, and the vertical axis is the SN ratio.
FIG. 7 is a characteristic diagram when the transmittance of electromagnetic waves in an artificial mist having a particle diameter changed in the range of 1 to 10 μm is measured under the same conditions.
FIG. 8 is a schematic configuration diagram showing a state when a video camera captures an image of an illumination area of a conventional vehicle headlight.
[Explanation of symbols]
1 Light source for illumination 2 Video camera 4 Headlight 5 Infrared camera 7 Vehicle 8 Road surface

Claims (1)

An illumination light source that is installed in the upper part of the vehicle and illuminates a front area of the vehicle, and a visible light or near infrared frequency band that is installed below the illumination light source in the vehicle and images the area illuminated by the light source. A first camera for imaging the road surface showing sensitivity and an obstacle imaging device such as a human who emits infrared rays showing sensitivity in an infrared frequency band around 10 μm that is installed in a vehicle and images the same as the first camera . the a second camera, respectively equipped with a resulting Ru means a composite image of an image captured by the first and second of each camera, the illumination light of the opening angle and the field of view of the first camera emitted from the illumination light source corners, with a smaller relations than the angle between the illumination light optical axis and the optical axis of the reflected light from the lighting region to the first camera, is disposed an illumination light source and the first camera It is characterized by Visual device.

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