JP2010286746A - Optical axis-adjusting device of stereo camera, and optical axis-adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adjust an optical axis of a stereo camera. <P>SOLUTION: An optical axis-adjusting device 20 of the stereo camera 10 includes: a pair of imaging elements 12L and 12R; a pair of optical systems 13L and 13R making each of the imaging elements form an image of an object; and a collimator holding and adjusting base 22. The collimator holding and adjusting base includes: a collimator 21; a slide adjusting means holding the collimator 21 to slide the collimator in the Y-axis direction and the Z-axis direction while keeping the collimator 21 horizontally to the X-Y plane; and a rotation adjusting means turning the collimator around the Z-axis. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical axis adjustment device and an optical axis adjustment method for a stereo camera having a pair of cameras.

  In a stereo camera that includes two cameras having an image sensor (CCD image sensor, CMOS image sensor, etc.) and a photographing optical system, and takes two images with parallax and measures the shape and distance of the object to be measured, In order to ensure and maintain measurement accuracy, it is necessary to adjust the optical axes of the two imaging optical systems with high accuracy.

  As a prior art regarding the optical axis adjustment of a stereo camera, it describes in the following patent document 1, for example. In this technique, a light source image (light emitting unit) obtained by rotating one of the left and right cameras facing a single spot light source and rotating the photographing optical system (lens barrel) of the one camera around the optical axis. Of the light source image obtained by causing the other camera to face the spot light source and rotating the imaging optical system of the other camera around the optical axis in the same manner. Thus, both optical axes are aligned.

JP 2008-51925 A

  However, the above-described prior art has a problem in that the operation of rotating the respective photographing optical systems by aligning the left and right cameras with respect to the spot light source is complicated and the work efficiency is poor.

  The present invention has been made in view of these points, and an object thereof is to easily adjust the optical axis of a stereo camera.

  An optical axis adjustment apparatus for a stereo camera according to the present invention is an optical axis adjustment apparatus for a stereo camera having a pair of imaging elements and a pair of optical systems for forming images of a subject on the imaging elements, a collimator, Slide adjusting means for holding the collimator and sliding the collimator in a first axis direction in the reference plane and a second axis direction orthogonal to the reference plane while maintaining a parallel state with respect to a predetermined reference plane. And a collimator holding and adjusting base having a rotation adjusting means for rotating about the second axis as a rotation center.

  The stereo camera optical axis adjustment method according to the present invention is a stereo camera optical axis adjustment method using the stereo camera optical axis adjustment device according to the present invention described above, wherein the optical system is removed from the stereo camera. In this state, the collimator holding / adjusting base adjusts the positional relationship of the collimator with respect to the stereo camera so that the image obtained by irradiating the image sensor with the light beam from the collimator coincides with a predetermined reference position. And the imaging device of the optical system so that an image obtained by irradiating the imaging device with a light beam from the collimator in a state where the optical system is attached to the stereo camera coincides with the reference position. Adjusting the positional relationship with respect to the optical axis.

  According to the present invention, there is an effect that the optical axis of the stereo camera can be easily adjusted.

It is a perspective view which shows the optical axis adjustment apparatus (before optical axis adjustment) of the stereo camera of embodiment of this invention. It is a perspective view which shows the optical axis adjustment apparatus (after optical axis adjustment) of the stereo camera of embodiment of this invention.

  Hereinafter, an optical axis adjustment device for a stereo camera according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, an XYZ orthogonal coordinate system as shown in FIGS. 1 and 2 is set, and this coordinate system will be referred to as appropriate. In this embodiment, the XYZ orthogonal coordinate system has the XY plane set as a horizontal plane and the Z axis set as a vertical direction.

  First, refer to FIG. The stereo camera 10 as an optical axis adjustment target includes a camera housing 11 and a pair of cameras (a left camera and a right camera). The pair of cameras are arranged on the left and right with a predetermined baseline length BL. The left camera has an image sensor 12L and a photographing optical system for forming an image of a subject on the image sensor 12R, and the right camera has an image sensor 12R. And a photographic optical system for forming an image of the subject on the photographic optical system.

  Each imaging optical system is configured by supporting lenses as optical devices in the lens barrels 13L and 13R. The lens barrels 13L and 13R of the photographing optical system are detachably attached to the camera housing 11. Further, the lens barrels 13L and 13R of the photographing optical system finely adjust their postures (rotations around the X, Y, and Z axes), that is, the directions of the optical axes 14L and 14R of the photographing optical system are finely adjusted independently. It is supported by the camera housing 11 via an adjustment mechanism (not shown) so that the adjustment can be performed. As the adjustment mechanism, the positions of the lens barrels 13L and 13R (positions in the X-axis, Y-axis, and Z-axis directions) may be finely adjusted.

  The imaging elements 12L and 12R are each composed of a CCD image sensor, a CMOS image sensor, or the like (both are assumed to be CCD image sensors in this embodiment), and have corresponding imaging optical systems (lens barrels 13L and 13R). An image of the subject imaged through is taken. The image sensors 12L and 12R are mounted on corresponding electronic boards, respectively.

  Imaging signals (video signals) captured by the imaging elements 12L and 12R are output via video signal cables 15L and 15R, respectively. In FIG. 1, the video signal cables 15L and 15R are connected to the video monitors 16L and 16R, and an image being shot is displayed in real time on the display screens of the video monitors 16L and 16R.

  The stereo camera 10 is detachably fixed at a predetermined position on the camera holding base 17 when adjusting the optical axis. The camera holding surface (upper surface in FIG. 1) of the camera holding base 17 is set substantially parallel to the XY plane as a reference plane, and the stereo camera 10 is positioned and fixed on the camera holding base 17. Thus, the direction of the base line length BL of the left and right cameras is substantially coincident with the Y-axis direction.

  The optical axis adjustment device 20 for adjusting the optical axis of the stereo camera 10 is arranged facing the stereo camera 10 fixed on the camera holding base 17, and includes a collimator 21 that emits a pair of light beams, and The collimator holding adjustment base 22 for holding the collimator 21 and finely adjusting the position and orientation thereof, and the collimator mounting base 23 for supporting the collimator holding adjustment base 22 are generally provided.

  The collimator 21 according to the present embodiment outputs two light beams and includes two light beam irradiation units. Each light beam irradiation unit has light sources 24L and 24R composed of laser diodes or the like, and converts the light emitted from the light sources 24L and 24R into parallel light via lenses (GRIN lens, convex lens, aspheric lens, etc.), respectively. As a light beam, the light beams exit from the corresponding light beam exits 21L and 21R.

  The irradiation axes 25L and 25R of each light beam are set so that the irradiation axes 25L and 25R of the respective light beams are parallel to each other with the same interval as the base line length BL of the stereo camera 10. The collimator 21 is fixed on the collimator holding base 26 of the collimator holding and adjusting mechanism 22 so that the light beam exits 21L and 21R face the stereo camera 10.

  The plane containing the irradiation axes 25L and 25R of each light beam, the upper surface of the holding table 26 of the collimator holding and adjusting table 22, and the upper surface of the camera holding table 17 are substantially parallel to each other. All the forms are substantially parallel to the XY plane.

  Although not shown, the collimator 21 further includes a distance measuring device (distance measuring means), a light flux control device (light flux control means), and a light quantity control device (light quantity control means). The distance measuring device is a distance measuring device for receiving the reflected light from the reflector (here, stereo camera 10) of the irradiated light beam and measuring the distance to the reflector. The light beam control device is a device for changing and adjusting (controlling) the cross-sectional shape (size) of the irradiated light beam (light beam). The light amount control device is a device for changing and adjusting (controlling) the light amount of the irradiated light beam. These distance measurement, light flux control, and light amount control can be performed for each light beam.

  The collimator holding and adjusting table 22 includes a slide adjusting mechanism (slide adjusting unit) that slides the collimator holding table 26 that holds the collimator 21 and a rotation adjusting mechanism (rotation adjusting unit) that rotates the collimator holding table 26. The slide adjusting device is configured to move the collimator 21 held on the collimator holding base 26 in the Y-axis direction (first axis direction) in the XY plane and the X-axis while maintaining the parallel state to the XY plane. -A mechanism for sliding in the Z-axis direction (second axis direction) orthogonal to the -Y plane. The slide adjustment mechanism can finely adjust the slide position in the Y-axis direction and the slide position in the Z-axis direction, and then fix the slide position in that position. The slide adjustment mechanism may include a mechanism that slides in the X-axis direction.

  Similarly, the rotation adjusting means is a mechanism for rotating the collimator 21 held on the collimator holding base 26 around the Z axis while maintaining a parallel state with respect to the XY plane. The rotation adjustment mechanism can finely adjust the rotation position around the Z axis and then fix the rotation position. The rotation adjustment mechanism may include a mechanism for rotating around the X axis and / or around the Y axis in order to finely adjust the parallel relationship between the upper surface of the collimator holding table 26 and the upper surface of the camera holding table 17.

  In the present embodiment, the video signals of the two image pickup devices 12L and 12R of the stereo camera 10 are displayed on the two video monitors 16L and 16R, respectively. The video signals of 12L and 12R may be switched and displayed on one video monitor, or each video signal may be superimposed and displayed simultaneously on one video monitor.

  The distance L1 between the stereo camera 10 (lens 13L, 13R) held on the camera holding base 17 and the collimator 21 may be set to an appropriate value according to the distance measurement accuracy required for the stereo camera 10. .

  Next, a method for adjusting the optical axis of the stereo camera 10 using the optical axis adjusting device 20 will be described. First, using the rotation adjustment mechanism of the collimator holding adjustment base 22 so that the irradiation axes 25L and 25R of the left and right light beams of the collimator 21 and the direction of the base line length BL of the left and right cameras of the stereo camera 10 intersect perpendicularly. Adjust the direction of rotation around the Z axis.

  For this adjustment, a distance measuring device provided in the collimator 21 is used. That is, a reflector made of a cover, a cap, an optical filter, or the like is attached to each of the lens barrels 13L and 13R of the imaging optical system of the left and right cameras so that the left and right light beams of the collimator 21 are reflected to measure the distance. The rotation angle θ around the Z axis is adjusted so that the distance from the light beam exit 21L to the lens barrel 13L measured by the apparatus is equal to the distance from the light beam exit 21R to the lens barrel 13R. If it is difficult to measure the distance at the lens barrels 13L and 13R, it is possible to use the reflection of the light beam from the camera housing 11 and the camera holder 17 having a plane parallel to the ZY plane. Good.

  Next, using the slide adjustment mechanism of the collimator holding and adjusting table 22 so that the centers of the irradiation axes 25L and 25R of the left and right light beams of the collimator 21 coincide with the centers of the corresponding image pickup devices 12L and 12R of the stereo camera 10. And slide adjustment in the Y-axis and Z-axis directions. In this adjustment, first, the light flux control device of the collimator 21 narrows the light flux to near the horizontal and vertical resolutions of the image sensors 12L and 12R, and at the same time, the light quantity control device suppresses the occurrence of smear, blooming, etc. The light beam is adjusted to an appropriate amount of light according to the dynamic range of the image sensors 12L and 12R so that a light source image favorable for axis adjustment can be obtained.

  Then, the lens barrels 13L and 13R are temporarily detached from the camera housing 11, the images captured by the image sensors 12L and 12R are monitored by the image monitors 16L and 16R, and the image monitors 16L and 16R captured by the image sensors 12L and 12R are displayed. The slide amount y in the Y-axis direction and the slide amount z in the Z-axis direction may be adjusted so that the light source images 18L and 18R on 16R are located at the center of the display screen (the intersection of the alternate long and short dash lines in the screen). Note that the irradiation of one light beam that is not required at this time may be stopped.

  Here, if the mounting positions of the two image sensors 12L and 12R of the stereo camera 10 are not accurate, the centers of the two light beam irradiation axes 25L and 25R are aligned with the centers of the image sensors 12L and 12R by the method described above. In such a case, the positions of the electronic boards on which the image pickup devices 12L and 12R are mounted must be correctly adjusted on the stereo camera 10 side. Normally, this adjustment is performed by moving only the electronic substrate of the other image sensor (for example, image sensor 12R) with reference to the position of either the left or right image sensor (for example, image sensor 12L).

  Finally, the lens barrels 13L and 13R of the photographing optical system once removed are reattached to the camera casing 11, and light source images 18L and 18R corresponding to the centers of the irradiation axes 25L and 25R of the left and right light beams are shown in FIG. As shown, the positions and angles of the lens barrels 13L and 13R are adjusted using the adjustment mechanism described above so as to be positioned at the center of the display screen of the video monitors 16L and 16R (the intersection of the alternate long and short dash lines in the screen). To do. This adjustment may be performed by adjusting the position and angle of the lenses in the lens barrels 13L and 13R. At this time, in order to obtain the light source images 18L and 18R suitable for the adjustment, it is preferable to appropriately adjust the light beam and the light amount again using the light beam control device and the light amount control device of the collimator 21.

  By using the optical axis adjusting device described above and adjusting the optical axis of the stereo camera through the above steps, a mirror of the photographing optical system centering on the optical axis as in the prior art described in Patent Document 1 described above. It is possible to easily perform accurate optical axis adjustment without performing a rotating operation around the optical axis of the cylinder.

  Once the collimator position and light beam irradiation angle have been adjusted, only the stereo camera on the camera holder is replaced and the optical axis is adjusted many times unless the collimator mount or camera holder is moved. Since it can be performed, it is particularly suitable for mass production.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment includes all design changes and equivalents belonging to the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Stereo camera, 11 ... Camera housing, 12L, 12R ... Image sensor, 13L, 13R ... Lens tube, 14L, 14R ... Optical axis, 16L, 16R ... Video monitor, 17 ... Camera holding stand, 18L, 18R ... Light source Image: 20 ... Optical axis adjusting device, 21 ... Collimator, 21L, 21R ... Light beam exit, 22 ... Collimator holding / adjusting base, 23 ... Collimator mounting base, 24L, 24R ... Light source, 25L, 25R ... Irradiation axis, 26 ... Collimator holder.

Claims (6)

A stereo camera optical axis adjusting device having a pair of image sensors and a pair of optical systems for forming images of subjects on the image sensors,
A collimator,
Slide adjusting means for holding the collimator and sliding the collimator in a first axis direction in the reference plane and a second axis direction perpendicular to the reference plane while maintaining a parallel state with respect to a predetermined reference plane And a collimator holding and adjusting base having a rotation adjusting means for rotating about the second axis as a rotation center. An optical axis adjusting device for a stereo camera, comprising: The collimator is
It is possible to irradiate two light beams at the same interval as the base line length of the stereo camera, and the irradiation axes of both light beams are set to be parallel,
Distance measuring means for measuring the distance to the stereo camera;
Luminous flux control means for controlling the shape of the light beam;
The optical axis adjusting device according to claim 1, further comprising: a light amount control unit that adjusts a light amount of the light beam.   3. The optical axis adjusting apparatus according to claim 2, wherein the distance measuring unit can measure the distance to the stereo camera independently for each light beam.   3. The optical axis adjusting device according to claim 2, wherein the light beam control means can narrow the light beam to a small light beam close to the horizontal and vertical resolution of the image sensor even when the optical system is removed.   The optical axis adjustment device according to claim 2, wherein the light amount control means can adjust the light amount so as not to cause smear or blooming according to the dynamic range of the image sensor even when the optical system is removed. An optical axis adjustment method for a stereo camera using the optical axis adjustment device according to any one of claims 1 to 5,
With the optical system of the stereo camera removed, the collimator holding / adjusting table allows the collimator to be adjusted so that an image obtained by irradiating the imaging device with a light beam from the collimator matches a predetermined reference position. Adjusting the positional relationship with respect to the stereo camera;
Positional relationship of the optical system with respect to the image sensor so that an image obtained by irradiating the image sensor with a light beam from the collimator with the optical system of the stereo camera matches the reference position A method for adjusting the optical axis of a stereo camera, comprising: adjusting the optical axis.

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