JP2008045983A - Adjustment device for stereo camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adjustment device for a stereo camera capable of shortening the time required for detection processing of a positional deviation of the camera. <P>SOLUTION: A calculation part 21b uses an image acquired by imaging an image 50 for adjustment by a camera 12 as a reference image, and moves an object image acquired by imaging the image 50 for adjustment by a camera 13, relative to the reference image, while calculating the area of each outer shape of two overlapped patterns 51a, 52a for adjustment at each position of the reference image. A position detection part 21b detects the minimum position, where the area value becomes a minimum by comparing each area value at each position. A control part 21 moves the camera 13 to the minimum position, by controlling a driving device 23, and adjustment for positional deviation is carried out. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adjustment device for a stereo camera that captures an adjustment pattern with a stereo camera and adjusts a displacement of a camera mounting position based on two images obtained by the imaging.

  Conventionally, as a three-dimensional measurement technique based on an image, a correlation between a pair of images obtained by capturing an object from different positions with two cameras (stereo cameras) is obtained, and a stereo camera mounting position, a focal length, and the like are obtained from parallax with respect to the same object. A technique for obtaining the distance to an object by the principle of triangulation using the camera parameters is known.

  Further, when an image is captured by a stereo camera, the stereo camera has a mechanical positional shift element, and appears as a shift in a pair of captured images. In a stereo camera, it is preferable that there is no shift other than parallax between captured images, and there is a problem that an accurate distance cannot be obtained if there is a shift other than parallax.

In order to solve such a problem, a stereo camera that captures an adjustment pattern with a stereo camera, calculates a positional deviation amount of the camera based on a pair of images obtained by the imaging, and adjusts the positional deviation. There are known adjustment devices. (For example, refer to Patent Document 1).
JP-A-10-115506

  However, in the stereo camera adjustment apparatus described in Patent Document 1, since the positional deviation is detected by calculating the city block distance, the positional deviation detection process becomes complicated, and the detection process takes time. There was a problem.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a stereo camera adjustment apparatus that can shorten the detection time of positional deviation.

  In order to solve the above-described problems, the stereo camera adjustment apparatus of the present invention causes the stereo camera to capture an adjustment pattern, and shifts the mounting position of the stereo camera based on two images obtained by the imaging. A stereo camera adjustment device for adjusting, an image obtained by imaging the adjustment pattern by one camera as a reference image, and a target image obtained by imaging the adjustment pattern by the other camera For each position of the reference image while moving with respect to the reference image, calculation means for calculating the area of the outline of the two overlapping adjustment patterns, and the minimum position where the area calculated by the calculation means is the smallest Position detecting means for detecting the position, and the other position at the minimum position detected by the position detecting means. And it is characterized in that it comprises a moving means for moving the camera.

  In addition, while the moving unit moves the other camera relative to the one camera, the calculating unit sequentially acquires the target image from the other camera, so that the target image becomes the reference image. You may move it.

  Further, the moving means includes a linearly moving means for linearly moving the other camera along two axes orthogonal to each other within a plane perpendicular to the optical axis of the other camera, and the optical axis as the center. It is preferable to provide a rotational movement means for rotating the other camera.

  In addition, it is preferable that after the translation shift parallel to the two axes is adjusted by the linear movement means, the rotation shift in the rotation direction around the optical axis is adjusted by the rotation movement means.

  According to the stereo camera adjustment device of the present invention, an image obtained by imaging the adjustment pattern with one camera is used as a reference image, and a target image obtained by imaging the adjustment pattern with the other camera is used as a reference. Stereo camera by moving the other camera to the minimum position where the area of the two overlapping adjustment patterns is calculated for each position of the control image while moving the image, and the area of the two overlapping adjustment patterns is minimized. Therefore, the time required for the position shift detection process can be shortened as compared with the case where the position shift is detected by calculating the city block distance or the like. For this reason, the adjustment process of the stereo camera can be performed quickly.

  Further, the moving unit moves the other camera relative to the one camera, and the calculating unit sequentially acquires the target image from the other camera, thereby moving the target image relative to the reference image. Therefore, it is possible to further reduce the time required for the stereo camera adjustment process.

  A stereo camera adjustment device (hereinafter, simply referred to as an adjustment device) 10 shown in FIG. 1 adjusts the displacement of the mechanical attachment position of the stereo camera unit 11. The stereo camera unit 11 includes a pair of left and right cameras 12 and 13. Each of the cameras 12 and 13 includes a solid-state imaging device such as a CCD image sensor. These cameras 12 and 13 are arranged at predetermined intervals so that their optical axes L1 and L2 are substantially parallel to each other. It is arranged. Below, the mechanical position shift of the cameras 12 and 13 is demonstrated.

  The cameras 12 and 13 have six positional deviation elements. As shown in FIG. 2, the optical axes L1 and L2 of the cameras 12 and 13 are defined as the Z axis, the vertical directions of the cameras 12 and 13 are defined as the Y axis, and the lateral directions of the cameras 12 and 13 are defined as the X axis. That is, the X axis and the Y axis are set to be orthogonal to each other in a plane perpendicular to the optical axes L1 and L2. In this XYZ orthogonal coordinate system, when the cameras 12 and 13 are attached at an interval of the set value X0, the camera 12 is used as a reference, and as shown in FIG. As shown in FIG. 2B, there are six mechanical positional deviations between the parallel translational deviations ΔX, ΔY, ΔZ and the rotational deviations Δα, Δβ, Δγ with respect to the coordinate axes X, Y, Z.

  Next, the configuration of the adjustment device 10 will be described. As shown in FIG. 1, the adjustment device 10 includes an image conversion unit 20, a control unit 21, and drive devices 22 and 23. The image conversion unit 20 includes A / D converters 31 and 32 and memories 33 and 34.

  The A / D converter 31 is connected to the camera 12, and converts an analog imaging signal captured by the camera 12 into image data of a digital signal having a predetermined luminance gradation (for example, 256 gradation gray scale). Convert. Further, the A / D converter 32 is connected to the camera 13, and converts the image signal picked up by the camera 13 into image data of a digital signal, like the A / D converter 31.

  The A / D converter 31 is connected to the memory 33 and outputs image data to the memory 33. Similarly, the A / D converter 32 is connected to the memory 34 and outputs image data to the memory 34.

  The control unit 21 acquires the image data stored in the memories 33 and 34, and detects the positional deviation of the cameras 12 and 13 based on these image data, as will be described later. Further, the drive device 22 includes a rectilinear drive unit 22a that moves the camera 12 in translational directions (XY directions), and a rotation drive unit 22b that rotates the camera 12 about the optical axis L1 in the γ direction. Yes.

  Further, like the drive device 22, the drive device 23 includes a straight drive unit 23a and a rotation drive unit 23b. These linear drive parts 22a and 22b and rotation drive parts 23a and 23b move each of the cameras 12 and 13 in each direction by rotating a screw with an actuator, for example. The control unit 21 adjusts the mechanical positional deviation of the cameras 12 and 13 by controlling the driving devices 22 and 23 based on the positional deviation of the cameras 12 and 13.

  Moreover, the above-mentioned control part 21 is provided with the calculation part 21a and the position detection part 21b. The calculation unit 21a uses, as a reference image, an image obtained by imaging the adjustment pattern with one of the cameras 12 and 13, and moves a target image obtained by imaging the adjustment pattern with the other relative to the reference image. However, the area of the outer shape of the two overlapping adjustment patterns is calculated for each position of the control image. In addition, as a calculation method of this area, you may calculate based on the coordinate of each vertex of an external shape, and may count the pixel contained in an external shape. The position detection unit 21b detects the minimum position where the area calculated by the calculation unit is the smallest. The control unit 21 determines the moving direction and moving amount of the cameras 12 and 13 corresponding to the minimum position, and controls the driving devices 22 and 23 based on the moving direction and moving amount to move the cameras 12 and 13. Adjust the misalignment.

  Next, regarding the adjustment processing of the mechanical position deviation of the cameras 12 and 13, an example in which the camera 12 is fixed and the camera 13 is moved with respect to the camera 12 to adjust the mechanical position deviation will be described. This will be described with reference to the flowchart of FIG.

  First, as shown in FIG. 4A, an adjustment image 50 including an adjustment pattern 50a is captured by the cameras 12 and 13. Since this adjustment pattern 50a is difficult to detect a rotation shift in a pattern of a point object such as a circle or a regular triangle, a shape that is not a point object by combining rectangles so that the rotation shift can be easily detected. Has been. At this time, image data captured by the camera 12 is stored in the memory 33, and image data captured by the camera 13 is stored in the memory 34.

  For example, an image 51 shown in FIG. 4B is stored in the memory 33, and an image 52 shown in FIG. 4C is stored in the memory 34, for example. The control unit 21 acquires the images 51 and 52 from the memories 33 and 34. Thereafter, based on these images 51 and 52, the translational deviations ΔX and ΔY and the rotational deviation Δγ are corrected.

  First, the correction of the translational deviation ΔX will be described. The calculation unit 21a uses the image 51 as a reference image, and moves the image 52, which is the target image, in the left-right direction (X-axis direction) in units of one pixel in the left-right direction at each position in the X-axis direction. The area of the outer shape of the two overlapping adjustment patterns 51 a and 52 a, that is, the area of the hatched portion in FIG. 5 is calculated, and the area value at each position is stored in the built-in memory of the control unit 21. Note that the moving range of the image 52 is larger than the range assumed as the translational deviation ΔX of the camera 13 in the X-axis direction.

  Thereafter, the position detection unit 21b detects the minimum position where the area value is the smallest by comparing the area values of the respective positions. That is, as shown in FIG. 6, when the position in the X-axis direction is the horizontal axis and the area value is the vertical axis, the minimum position X1 where the area value is minimum is detected.

  Based on the minimum position X1, the control unit 21 determines the moving amount and moving direction of the camera 13 for correcting the translational deviation ΔX. Thereafter, the control unit 21 controls the driving device 23 based on the movement amount and the movement direction, and moves the camera 13 to correct the translational deviation ΔX.

  Next, correction of the translational deviation ΔY will be described. In this case, the calculation unit 21a moves the image 52 in the vertical direction (Y-axis direction) with respect to the image 51 in units of one pixel, and the area at each position in the Y-axis direction as in the case of the translational deviation ΔX. Calculate and store the value. Further, the position detector 21b detects the minimum position Y1 having the smallest area value, as in the case of the translational deviation ΔX. Based on the minimum position Y1, the control unit 21 determines the movement amount and movement direction of the camera 13 for correcting the translational deviation ΔY, and controls the driving device 23 based on the movement amount and movement direction. The camera 13 is moved to adjust the translational deviation ΔY. Also in this case, the moving range of the image 52 is set larger than the range assumed as the translational deviation ΔY of the camera 13.

  After adjusting the translational deviations ΔX and ΔY, the rotational deviation Δγ is adjusted. Hereinafter, the adjustment of the rotational deviation Δγ will be described. The control unit 21 controls the drive device 23 to sequentially acquire the images 52 while rotating the camera 13 in the γ direction. The calculating unit 21a calculates the area of the outer shape of the two overlapping adjustment patterns 51a and 52a at each rotational position in the γ direction, that is, the area of the portion indicated by the diagonal lines in FIG. It is stored in the built-in memory of the control unit 21. Note that the rotation range of the camera 13 is larger than the range assumed as the rotation deviation Δγ of the camera 13.

  Thereafter, the position detection unit 21b detects the rotation position having the smallest area value by comparing the area values of the respective rotation positions in the γ direction. That is, as shown in FIG. 8, when the rotation position in the γ direction is the horizontal axis and the area value is the vertical axis, the rotation position γ1 having the smallest area value is detected. Thereafter, the control unit 21 controls the driving device 23 based on the rotational position γ1, thereby fixing the camera 13 at the rotational position γ1 and adjusting the rotational deviation Δγ. Since the cameras 12 and 13 have parallax, the adjustment patterns 51a and 52a do not completely coincide with each other, but a mechanical positional shift other than parallax is adjusted.

  Further, in the description of the adjustment process, the case where the positional deviation of the camera 13 with respect to the camera 12 is adjusted has been described as an example. However, the positional deviation of the camera 12 with respect to the camera 13 can be similarly adjusted. Also in this case, detailed description will be omitted because the same processing can be performed.

  As described above, one of the two images obtained by imaging the adjustment pattern is used as a reference image, and the other target image is moved with respect to the reference image, and these two overlapping adjustment patterns are overlapped. Since the area of the outer shape of the camera is calculated and the camera is moved to the position where the area value is the minimum, the detection process of the position shift is simplified compared to the case where the position shift is detected by calculating the city block distance, etc. Is done. For this reason, the adjustment process of the mechanical position shift of a camera can be performed rapidly.

  In the above embodiment, the case where the moving means is provided in each of the two cameras has been described as an example. However, the present invention is not limited to this. When only the positional deviation of the other camera with respect to one camera is adjusted, the other It is sufficient to provide moving means only for these cameras.

  In the above embodiment, the case where only the translational deviations ΔX and ΔY are adjusted has been described as an example. However, the translational deviation ΔZ may be similarly adjusted. Moreover, although the case where only the rotational deviation Δγ is adjusted has been described as an example, the rotational deviations Δα and Δβ may be similarly adjusted. In these cases, an actuator corresponding to the translational deviation ΔZ and the rotational deviations Δα and Δβ may be provided in the driving device.

  Further, in the above embodiment, when adjusting the translational deviation, the area value at each position is calculated while moving the target image with respect to the reference image without moving the camera, and the area value is minimized. The case where the camera position is adjusted to the position is described as an example. However, the present invention is not limited to this, and the target image is moved relative to the reference image by moving the camera, as in the case of adjusting the rotational displacement. You may let them. Conversely, when adjusting the rotational displacement, the rotational position for adjusting the rotational displacement of the camera is determined based on the area value while rotating the target image with respect to the reference image without rotating the camera. Also good.

  Further, in the above embodiment, the case where the rotational deviation is adjusted after adjusting the translational deviation has been described as an example. However, the present invention is not limited to this, and the translational deviation may be adjusted after adjusting the rotational deviation. good.

It is a block diagram which shows the electrical structure of the adjustment apparatus of a stereo camera. It is a perspective view which shows the mechanical position shift of a stereo camera. It is a flowchart explaining the adjustment process of position shift. It is explanatory drawing which shows two images which imaged the image for adjustment, and this adjustment pattern with the stereo camera. It is explanatory drawing which shows the external area of the movement of the image of a translation direction, and an adjustment pattern. It is a graph which shows the relationship between the position of an X-axis direction, and an area value. It is explanatory drawing which shows the rotation of the image of (gamma) direction, and the area of an external shape. It is a graph which shows the relationship between the rotation position of (gamma) direction, and an area value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stereo camera adjustment apparatus 11 Stereo camera 12, 13 Camera 21 Control part 21a Calculation part 21b Position detection part 22, 23 Drive apparatus 22a, 23a Straight drive part 22b, 23b Rotation drive part 50 Image for adjustment 50a Adjustment pattern

Claims (4)

In an adjustment apparatus for a stereo camera that images an adjustment pattern with a stereo camera and adjusts a shift in the mounting position of the stereo camera based on two images obtained by the imaging,
The image obtained by imaging the adjustment pattern with one camera is used as a reference image, and the target image obtained by imaging the adjustment pattern with the other camera is moved with respect to the reference image. Calculating means for calculating the area of the outer shape of the two overlapping adjustment patterns for each position of the control image;
Position detecting means for detecting a minimum position where the area calculated by the calculating means is smallest;
An apparatus for adjusting a stereo camera, comprising: moving means for moving the other camera to the minimum position detected by the position detecting means.   While the moving unit moves the other camera relative to the one camera, the calculating unit sequentially acquires the target image from the other camera, whereby the target image is compared with the reference image. The stereo camera adjustment apparatus according to claim 1, wherein the stereo camera adjustment apparatus is moved.   The moving means includes a rectilinear moving means for moving the other camera straight along two axes orthogonal to each other in a plane perpendicular to the optical axis of the other camera, and the other camera about the optical axis. 3. The stereo camera adjustment apparatus according to claim 1, further comprising a rotation moving unit that rotates the camera.   4. The rotational shift in the rotational direction about the optical axis is adjusted by the rotational movement means after adjusting the translational deviation parallel to the two axes by the linear movement means. Stereo camera adjustment device.

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