JPH05172567A - Passive range finder - Google Patents

Abstract

PURPOSE:To measure the distance to an object to be measured by one sensing action with one camera by dividing light from a part to be measured into lights of two colors with a filter to form an image with a color CCD camera through a different part of an imaging lens. CONSTITUTION:A color CCD camera 1 has a color filter 12 in front of an imaging lens 11 to transmit at least two colors of red, blue and green. The lights of two colors divided with the filter 12 form images separately on the surface of the color CCD element 13 of the camera 1 passing through portions of different areas of the lens 11 and the images thus formed generate a parallax as the same object is viewed from two different locations. A parallax computing section 21 calculates the parallax attributed to the filter 12 from an image signal formed on the surface of the element 13. A distance computing section 22 calculates the distance to the object to be measured by an image formation formula using the parallax calculated with the computing section 21. This enables the measurement of the distance of the object to be measured with one camera thereby achieving higher accuracy with respect to deviation of an optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive distance measuring device mounted on a robot arm, a mobile robot or the like and serving as an eye. In particular, the present invention refers to an improvement of the passive distance measuring device that enables the distance to the object to be measured with one sensing (imaging) by one camera.

[0002]

2. Description of the Related Art FIG. 8 is a view showing a conventional passive distance measuring device. In this figure, the two cameras (1 _A , 1 _B ) are placed apart by l, and the observation lens node 0 _A ,
0 and _B, the observation lens 0 _A, 0 _B and the observation plane in the position of the focal length _{f (x a, y a)} , and (x _b, y _b), the coordinates P
A passive range finder which constitutes an observation optical system consisting of an object to be measured at (x, y, z) is shown.

The distance to the object is determined by the two images (stereo images) with the parallax 1 obtained from the device shown in FIG.

[0004]

[Equation 1]

Is given as

[0006]

However, since the conventional passive distance measuring device requires two cameras, it is necessary to strictly calibrate parameters such as the degree of inclination of the optical axis between the cameras. However, if these parameters are changed even a little, all the settings of the image processing system that follows will have to be changed, so stable performance will be obtained when used as an eye, for example, when installed in a robot that receives various accelerations such as vibration. There was a problem that could not be guaranteed for a long time. Further, since two cameras are used, there is a problem that a system of two systems is always required for transmission and recording of image information, and the two need to be synchronized.

Therefore, the present invention has been made in view of the above problems.
To provide a passive distance measuring device capable of measuring a distance to an object to be measured with one sensing by one camera by solving the drawbacks of the conventional passive distance measuring device with two cameras. With the goal.

[0008]

FIG. 1 is a diagram showing the principle configuration of the present invention. The present invention has an image pickup unit 1 in a passive distance measuring apparatus in order to solve the above problems. The image pickup unit 1 is a color camera and has a filter means 12.
In the filter means 12, at least two color filters 121, 122 of the color filters that transmit only red, blue, and green light are installed near the imaging lens 11 of the color camera. Further, the present invention has the image processing unit 2 including the parallax calculation unit 21 and the distance calculation unit 22. The parallax calculation unit 21 performs a calculation process for obtaining the parallax of the image of the measurement target formed from the image signal from the image pickup unit (1) divided into at least two colors of red, blue, and green. ..

The distance calculator 22 performs a calculation process for obtaining the distance to the object to be measured using the parallax.

[0010]

Referring to FIG. 1, according to the passive distance measuring apparatus of the present invention, the light from the object to be measured is divided by the filter means 12 into light of at least two different colors, and different areas of the imaging lens 11 are provided. And the images are formed on the surface of the color CCD element 13 of the color CCD camera 1, respectively, and these images form parallax when the same object is seen from two different places.

The parallax calculator 21 controls the color CCD device 13
The parallax by the filter means 12 is calculated from the image signal formed on the surface. The distance calculation unit 22 calculates the distance to the measurement object from the imaging formula using the parallax calculated by the parallax calculation unit 21. Thus, according to the passive distance measuring apparatus of the present invention, the distance to the object to be measured can be measured with one camera, so that the accuracy can be improved against the deviation of the optical axis as in the conventional case, and the structure can be improved. Will be easier.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a diagram showing a passive distance measuring apparatus according to an embodiment of the present invention. The configuration of this figure will be described. The passive range finder of this figure has an image forming lens 11 and a filter means 12 in which at least two color filters among red, blue and green color filters are installed in front of the image forming lens 11.
And a color CCD (Charge Cou
pled device) A color CCD camera 1 equipped with a device 13
And an image signal from the color CCD camera 1,
A parallax calculator 21 that performs a calculation process for obtaining parallax (S) of an image of a measurement target formed by dividing at least two colors of red, blue, and green, and a measurement target using the parallax (S). Distance calculation unit that performs calculation processing to calculate the distance to
An image processing unit 2 including a central processing unit (CPU) (not shown), a storage unit (ROM) for storing an interface control program and the like, and the color CCD element 13
A signal line 3 for transmitting the color composite signal output from the
An RGB divider 4 that is divided into (red), G (green), and B (blue), and an R signal that is divided by the RGB divider 4,
The signal lines 5, 6 and 7 for transmitting the G signal and the B signal, respectively, and the display unit 8 for displaying the distance to the measurement object calculated by the image processing unit 2 and including a liquid crystal display or the like. Including.

FIG. 3 is a diagram showing the filter means in FIG. In this figure (a), the filter means 2 is provided with a red filter 121 which transmits only red light and a blue filter which transmits only blue light, and does not transmit any light in other regions of the filter means 2. Similarly, in the figure (b), the red filter 121 and the green filter 122 which transmits only green light to the filter means 2, the blue filter 121 and the green filter 122 in the figure (c), and the red filter 121 in the figure (d). , Blue filter 122 and green filter 123
Are provided so that no light is transmitted in the other areas of the filter means 2.

In FIG. 2, the filter means 2 is an image forming lens 11
Although it is provided outside the image forming lens 11, it may be provided inside the image forming lens 11, and the image forming lens 11 itself has a structure shown in FIG.
The color filter of (d) may be provided. It is 3 to use the filter of three colors of red, blue and green in Fig. 3 (d).
This is because it enables sensing from one viewpoint, and enables distance measurement even for a measurement object extending in the horizontal direction or the vertical direction.

As filters for three colors, R-60, G-530, and B-390, which transmit only red, blue, and green, are available on the market. Next, the operation of this embodiment will be described.
In order to simplify the description, as shown in FIG. 3A, the red filter 121 and the blue filter 12 for the filter means 2 are used.
The case where the two-color filter of 2 is used will be described.

First, the visual field of the color CCD camera 1 is aimed at the object to be measured. The light emitted from the object to be measured is filtered
It is taken into the color CCD camera 1 via 12. That is, only the red component of the light emitted from the object to be measured passes through the red filter 121 and forms an image on the color CCD element 13 via the imaging lens 11. Similarly, only the blue component can pass through the blue filter 122 and forms an image on the color CCD element 13 via the imaging lens 11.

That is, on the image forming surface of the color CCD element 13, the red light transmitted through the upper half of the image forming lens and the blue light transmitted through the lower half are mixed to form an image. Next, the mixed image of red and blue is converted into an electric signal by the color CCD element 13, synthesized and sent to the signal line 3 as an output composite signal of the color CCD camera 1.

This composite signal is the RGB divider 4
Is input to the RGB divider 4 and is decomposed into an R signal and a B signal by the RGB divider 4. The R signal thus decomposed and obtained becomes an image by the light transmitted through the red portion of the red filter 121, that is, the upper half, and the image by the B signal is the light transmitted through the blue portion of the blue filter 122, that is, the lower half. It becomes the image by.

As described above, when viewed from the color CCD camera 1, an image viewed through the upper half of the imaging lens and an image viewed through the lower half of the same measuring object can be obtained at the same time. That is, two images with parallax when the same measurement object is viewed from two different places are obtained at the same time. This is a kind of stereo image taken from two directions.

Next, the R image signal and the B image signal are
Input to the image processing unit 2 and calculate the distance to the measurement object
It FIG. 4 shows a flow chart of the arithmetic processing in the arithmetic processing unit of FIG.
It is a row chart. As shown in FIG.
The parallax calculation unit 21 performs the following parallax calculation processing (step
1). In this parallax calculation process, the coordinates of the R signal are set to (x_Ri，
y_Ri), The coordinates of the B signal are (x_Bi, Y_Bi) And R image
And the barycentric coordinates of the B image are (x_R, Y _R)and
(X_B, Y_B),

[0021]

[Equation 2]

Here, it is assumed that the coordinates imaged on the color CCD element 13 are w _i = 1.0 and the coordinates not imaged are w _i = 0. The parallax S is

[0023]

[Equation 3]

Is obtained as Next, when S = 0, the object to be measured is at the focus-matching position, as is clear from the calculation process of the measurement distance described later. First, the case where the object to be measured is in the focus position of the color CCD camera 1 will be described (step 2). FIG. 5 is a diagram showing an image formed when a measurement object is present on the focus position. This figure shows the color CCD camera 1 and the measuring object 100 in a simplified manner, and the actual measuring object exists at a distance. A case where the red filter 121 and the blue filter 122 are used as in the above will be described. In FIG. 5, the light from the measuring object 100 passes through the red filter 121 and the blue filter 122, and forms an image at the same position on the color CCD element 13 via the imaging lens 11. RGB divider 4
The R signal and the B signal decomposed in step S1 are input to the arithmetic processing unit 2 as described above, and the parallax arithmetic unit 21 of the image processing unit 2 outputs the R signal.
The signal and the B signal are determined by the parallax S = 0 that the measurement object is on the focus when the image of the measurement object exists in the same portion of the color CCD element 13.

When the above determination is made, the distance calculation unit 22 of the calculation processing unit 2 performs the following distance calculation process to the object to be measured. If the focal length of the color CCD camera 1 is f when the focus position is on,

[0026]

[Equation 4]

Here, a is from the imaging lens 11 to the object 10 to be measured.
B is the distance from the imaging lens 11 to the color CC
This is the distance to the D element 13 (step 3). If S ≠ 0,
Focusing is performed when the barycentric coordinates (x _R , y _R ) and (x _B , y _B ) of the R image and the B image are in the lower half and the upper half of the red filter 121 and the blue filter 122 of the filter means 2. It is determined that the measurement object exists farther than the position (step 4).

Next, a case will be described in which the measuring object is located farther than the focus matching position. FIG. 6 is a diagram showing an image formed when a measurement object is present at a distance from the focus position. As shown in the figure, when there is a red filter 121 on the upper half side of the imaging lens 11, the light from the measuring object 100 passes through the red filter 121 and passes through the upper half side of the imaging lens to pass through the color CCD element. The image is formed on the lower half side of surface 13. The blue light passing through the blue filter 122 is imaged on the upper half side of the surface of the color CCD element 13 via the lower side of the imaging lens 11. Then, the color composite signal from the color CCD element 13 is input to the image processing unit 2 via the RGB divider 4. Here, as shown in FIG. 6, there is a parallax S in the red image of the measuring object 100 and the blue image, and in this case, the blue image exists above it in FIG. 6 when the red image is used as a reference.
Here, the parallax S is calculated by the parallax calculation processing unit 21. When the distance between the barycentric positions of the red filter 121 and the blue filter 122 is D,

[0029]

[Equation 5]

By erasing and arranging l from both equations, the distance L to the object to be measured 100 is

[0031]

[Equation 6]

That is, the distance L to the measurement object 100 can be calculated using the parallax S calculated by the parallax calculation unit 21 (step 5). Next, a case will be described in which the measurement target exists near the focus position. FIG. 7 is a diagram showing an image formation in the case where the measuring object is present near the focus position. As shown in FIG. 7, when the red filter 121 is provided on the upper half side of the filter means 2, the light from the measuring object 100 passes through the red filter 121 and the imaging lens.
An image is formed on the upper side of the surface of the color CCD element 13 through the upper half side of 11. The blue light that has passed through the blue filter 122 forms an image on the lower side of the surface of the color CCD element 13 via the lower half side of the imaging lens 11. Then, the color composite signal from the color CCD element 13 is input to the image processing unit 2 via the RGB divider 3. Here, as shown in FIG. 7, there is a parallax S between the red image and the blue image of the measuring object 100. In this case, with the red image as the reference, the blue image exists below the figure. Here, similarly to the above, using the parallax S calculated by the parallax calculation unit 21,

[0033]

[Equation 7]

By erasing and arranging l from both equations, the short distance L to the object to be measured 100 is

[0035]

[Equation 8]

That is, the distance L to the measurement object can be calculated by calculating the parallax S (step 6). The distance L to the measurement object calculated in this way is displayed on the display unit 8 (step 7).

[0037]

As described above, according to the present invention, at least two color filters are installed near the image forming lens of the color camera, and from the parallax of the measuring object formed by the image signals of each color, Since the distance to the measurement target is calculated, the distance to the measurement target can be measured with one color camera, and the signal processing system etc.
It can be done in the system. In other words, the optical axis alignment between the two cameras and the synchronization of the two systems, which are indispensable in the conventional distance measuring device using the two cameras, are not required, and therefore the structure is very simple. It is possible to provide a highly reliable distance measuring device.

[Brief description of drawings]

FIG. 1 is a diagram showing a principle configuration of the present invention.

FIG. 2 is a diagram showing a passive distance measuring device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a filter means in FIG.

FIG. 4 is a flowchart illustrating a calculation process in a calculation processing unit in FIG.

FIG. 5 is a diagram showing an image formed when a measurement object is present on a focus position.

FIG. 6 is a diagram showing imaging when a measurement target object is present at a distance from the focus position.

FIG. 7 is a diagram showing an image formed when a measurement target object is located closer than a focus position.

FIG. 8 is a diagram showing a conventional passive distance measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Imaging part 2 ... Image processing part 11 ... Imaging lens 12 ... Filtering means 13 ... Color CCD element 21 ... Parallax calculation part 22 ... Distance calculation part 121,122 ... Color filter

Claims (1)

[Claims] 1. An image pickup section (1) for picking up and inputting an image of a measurement object, and an image processing section (2) for calculating a distance to the measurement object based on image data from the image pickup section (1). In the passive distance measuring device, the image pickup unit (1) is a color camera, and at least a color filter that transmits only red, blue, and green light near the imaging lens (11) of the color camera. It has a filter means (12) in which two color filters (121, 122) are installed, and the image processing section (2) is an image signal from the image pickup section (1), A parallax calculation unit (21) for performing a calculation process for calculating a parallax of an image of a measurement target formed from at least two colors of green, and a calculation process for calculating a distance to the measurement target using the parallax. And a distance calculation unit (22) for performing Dogata distance measuring device.