Mechanical Calibration Device and Method for Spatial Relationship between Optical Plane and Camera Photosensitive Plane

Abstract

A mechanical calibration device and method for the spatial relationship between a light plane and a camera photosensitive plane, belonging to the technical field of calibration of planar spatial relationships. It includes a calibration base, a light plane calibration block, a camera photosensitive plane calibration block, and a light plane projection scale arranged on the calibration base. The spatial relationship of the light plane relative to the calibration base is calibrated through the light plane calibration block and the light plane projection scale; the spatial relationship of the camera photosensitive plane relative to the calibration base is calibrated through the camera photosensitive plane calibration block; through the spatial relationships between the light plane calibration block and the camera photosensitive plane calibration block and the calibration base, it is possible to calibrate the spatial relationship between the light plane and the camera photosensitive plane in a mechanical manner, and realize the calibration of any angle between the light plane and the camera photosensitive plane in space, having the advantages of simple structure and being convenient for processing and implementation.

Description

Technical Field

[0001] The present invention belongs to the technical field of calibration of planar spatial relationships, and particularly relates to a mechanical calibration device and method for the spatial relationship between a light plane and a camera photosensitive plane. Background Art

[0002] Using lasers and cameras for measurement is a common non-contact measurement method at present, and an important example is the laser triangulation method.

[0003] The laser triangulation method utilizes the spatial relationship between a laser plane and a camera photosensitive plane to achieve the measurement of an object irradiated by a laser within the depth of field of the camera.

[0004] Since the measurement process requires calibration of the light plane and the camera photosensitive plane, that is, understanding the spatial relationship between the light plane and the camera photosensitive plane, otherwise accurate measurement cannot be performed. Therefore, for the relationship between the two planes, there are many software algorithms, such as by means of external markers, through complex algorithms, to obtain the spatial relationship between the light plane and the camera photosensitive plane.

[0005] These software methods require the production of external markers, and during the operation process, the operator needs to perform different pose transformations on the markers, and only after multiple operations and software calculations can the spatial relationship be obtained. At the same time, many software have copyright restrictions.

[0006] For manufacturers with such application requirements, in most cases, what is needed is the ideal spatial relationship between the light plane and the camera photosensitive plane. However, since there is no way to observe the spatial positions of the light plane or the camera photosensitive plane, only in the later stage of the product can the spatial relationship between the non-ideal light plane and the camera photosensitive plane be obtained through the software method as described above, and mathematical methods are used for compensation to make the product as close as possible to the performance in the ideal spatial relationship state of the light plane and the camera photosensitive plane during use. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a mechanical calibration device and method for the spatial relationship between a light plane and a camera photosensitive plane.

[0008] The technical solution adopted by the invention is: a mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane. The technical key points are as follows: It includes a calibration base, an optical plane calibration block, a camera photosensitive plane calibration block, and an optical plane projection scale arranged on the calibration base. The optical plane calibration block has a slit through which the laser beam emitted by the laser emitter passes and projects the laser beam onto the plane projection scale. The laser emitter is installed within the frame of the calibration base, and the laser beam emitted by the laser emitter passes through the first light-transmitting hole of the frame and shoots out. The camera photosensitive plane calibration block has a slit for the camera to capture the laser beam on the plane projection scale. The camera is installed within the frame and captures images through the second light-transmitting hole of the frame.

[0009] In the above solution, the center point of the laser emitter is at the same height as the zero point on the optical plane projection scale.

[0010] In the above solution, the center point of the camera is at the same height as the zero point on the optical plane projection scale.

[0011] In the above solution, the spatial angle between the optical plane calibration block and the camera photosensitive plane calibration block is equal to the spatial angle between the optical plane where the laser beam is located and the camera photosensitive plane where the light rays emitted by the camera are located.

[0012] A method for calibrating the spatial relationship between the optical plane and the camera photosensitive plane. The technical key points are as follows: It includes the following steps:

[0013] Install the optical plane calibration block, the camera photosensitive plane calibration block, and the optical plane projection scale on the calibration base respectively.

[0014] Calibrate the spatial relationship of the optical plane relative to the calibration base through the optical plane calibration block and the optical plane projection scale; calibrate the spatial relationship of the camera photosensitive plane relative to the calibration base through the camera photosensitive plane calibration block; determine the spatial relationship between the optical plane and the camera photosensitive plane through the spatial relationships between the optical plane, the camera photosensitive plane, and the calibration base.

[0015] In the above solution, the process of calibrating the spatial relationship of the optical plane relative to the calibration base through the optical plane calibration block and the optical plane projection scale is as follows:

[0016] The laser emitter works, causing the laser generator to emit a laser beam to form an optical plane.

[0017] Adjust the spatial position of the laser emitter so that the optical plane where the laser is located passes through the slit of the optical plane calibration block and projects onto the optical plane projection scale.

[0018] Adjust the position of the laser emitter so that the center point of the laser emitter is at the same height as the zero point on the optical plane projection scale.

[0019] In the above solution, the spatial relationship between the camera's photosensitive plane and the calibration base is calibrated by a camera photosensitive plane calibration block. The process is as follows:

[0020] Adjust the height of the camera's center point from the calibration base so that the height of the camera's center point is the same as the zero point on the light plane projection scale;

[0021] Enable the camera to capture the laser line projection formed on the light plane projection scale through the camera photosensitive plane calibration block and image it on the camera's photosensitive plane;

[0022] Continue to adjust the position of the camera so that the image is located at the center horizontal or vertical position of the camera's photosensitive plane.

[0023] In the above solution, the spatial relationship between the light plane and the camera's photosensitive plane is determined based on the spatial relationships between the light plane and the camera's photosensitive plane and the calibration base. The process is as follows:

[0024] Observe the light plane projection scale:

[0025] If a laser line projection cannot be formed on the light plane projection scale, it proves that the spatial relationship between the light plane and the calibration base is incorrect, and the attitude of the laser generator needs to be adjusted;

[0026] If a laser line is formed on the light plane projection scale but the scale reading is too high or too low, it proves that the spatial relationship between the light plane and the calibration base is incorrect in one direction, and the attitude of the laser generator needs to be adjusted;

[0027] Observe the camera image:

[0028] If the camera cannot capture the laser line projection formed on the light plane projection scale through the camera photosensitive plane calibration block and image it on the camera's photosensitive plane, it proves that the spatial relationship between the camera's photosensitive plane and the calibration base is incorrect, and the position of the camera needs to be adjusted;

[0029] If the image on the camera's photosensitive plane is not in the center of the camera's photosensitive plane, it proves that the spatial relationship between the camera's photosensitive plane and the calibration base is incorrect, and the position of the camera needs to be adjusted.

[0030] The beneficial effects of the present invention are as follows: The mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane includes a calibration base, an optical plane calibration block, a camera photosensitive plane calibration block, and an optical plane projection scale arranged on the calibration base. The spatial relationship between the optical plane and the calibration base is calibrated by the optical plane calibration block and the optical plane projection scale; the spatial relationship between the camera photosensitive plane and the calibration base is calibrated by the camera photosensitive plane calibration block; through the spatial relationship between the optical plane calibration block and the camera photosensitive plane calibration block and the calibration base, it is possible to calibrate the spatial relationship between the optical plane and the camera photosensitive plane in a mechanical manner, and realize the calibration of any angle between the optical plane and the camera photosensitive plane in space. It has the advantages of simple structure and easy processing and implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is a schematic structural diagram of the mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane in the embodiment of the present invention;

[0033] Figure 2 is Figure 1 the top view of;

[0034] Figure 3 It is a schematic structural diagram of the optical plane calibration block in the embodiment of the present invention;

[0035] Figure 4 It is a schematic structural diagram of the optical plane projection scale in the embodiment of the present invention;

[0036] Figure 5 It is a schematic structural diagram of the camera photosensitive plane calibration block in the embodiment of the present invention;

[0037] Explanation of the serial numbers in the figure: 1 optical plane calibration block, 2 camera photosensitive plane calibration block, 3 optical plane projection scale, 4 calibration base, 5 laser emitter, 6 camera. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will further describe the present invention in detail with reference to the Figures 1 to 5 drawings and specific embodiments. Embodiment 1:

[0039] The mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane adopted in this embodiment includes an optical plane calibration block 1, a camera photosensitive plane calibration block 2, an optical plane projection scale 3, a calibration base 4, a laser emitter 5, and a camera 6. The optical plane calibration block 1 in this embodiment is made by machining or printing. It consists of two calibration blocks on the left and right. The opposite surfaces of the two calibration blocks are machined with grooves. The surface of the groove can be arc-shaped or other shapes, without specific limitations, as long as it is ensured that the inside is hollow after the two calibration blocks are placed, and a gap through which the common laser ray passes is formed between the two calibration blocks. This structure is firm and easy to process, and the formed gap is not easily damaged. The plane passed by the optical plane is determined through two straight gaps. In this embodiment, the optical plane refers to the plane constrained by a beam of plane scattered light emitted by the laser emitter.

[0040] The camera photosensitive plane calibration block 2 in this embodiment is made by machining or printing. It consists of two prism-shaped calibration blocks. By adjusting the distance between the two prisms, a suitable gap is obtained, so that the camera 6 can observe the light of the laser emitter 5 on the optical plane projection scale 3 through the gap.

[0041] The optical plane projection scale 3 adopted in this embodiment is made by machining or printing and can be moved back and forth on the calibration base 4 in the laser emission direction to calibrate the distance h between the laser emitter 5 and the optical plane projection scale 3, and indirectly calibrate the designed distance l between the laser emitter 5 and the camera 6. The optical plane projection scale 3 has scales. Since the center point of the laser emitter 5 is adjusted to be at the same height as the zero point of the optical plane projection scale 3, the installation angle of the laser emitter 5 in space can be determined by the length above and below the zero point of the projection formed by the laser emitter 5 on the optical plane projection scale 3.

[0042] The calibration base 4 in this embodiment is a metal base with extremely small deformation. The optical plane calibration block 1, the camera photosensitive plane calibration block 2, and the optical plane projection scale 3 are all installed on the calibration base 4. The spatial relationship between the optical plane and the calibration base 4 is calibrated through the optical plane calibration block 1 and the optical plane projection scale 3. The spatial angle between the optical plane calibration block 1 and the camera photosensitive plane calibration block 2 is equal to the spatial angle between the optical plane formed by the laser line and the camera photosensitive plane of the camera. In this embodiment, the camera photosensitive plane is the imaging photosensitive component plane inside the camera, usually inside the camera, and its accurate digital model or actual position cannot be obtained.

[0043] The mechanical calibration method for the spatial relationship between the optical surface and the camera photosensitive plane can calibrate the spatial relationship between the optical plane of the laser emitter 5 and the camera photosensitive plane of the camera 6 by adjusting the spatial relationship among the optical plane calibration block 1, the camera photosensitive plane calibration block 2, the optical plane projection scale 3, and the calibration base 4, including the following steps:

[0044] The optical plane calibration block 1, the camera photosensitive plane calibration block 2, and the optical plane projection scale 3 are respectively installed on the calibration base 4.

[0045] The laser emitter 5 and the camera 6 are fixed on the calibration base 4 through a frame. The frame is provided with a first light-transmitting hole and a second light-transmitting hole. The laser line emitted by the laser emitter 5 passes through the first light-transmitting hole and exits, and the camera 6 captures light and forms an image through the second light-transmitting hole. The relative positions of the laser emitter 5 and the camera 6 can be finely adjusted.

[0046] Calibrate the spatial relationship between the calibration optical plane calibration block 1 and the camera photosensitive plane calibration block 2 so that the spatial angle between the calibration optical plane calibration block 1 and the camera photosensitive plane calibration block 2 reaches the target requirement, that is, the designed angle θ between the required optical plane and the camera photosensitive plane.

[0047] Calibrate the distance between the laser emitter 5 and the optical plane projection scale 3 to reach the target requirement. This distance depends on the angle between the required optical plane and the camera photosensitive plane and the distance h between the laser emitter 5 and the camera 6. The distance h can be simply obtained through the designed distance l between the laser emitter 5 and the camera 6 and the designed angle θ between the optical plane and the camera photosensitive plane.

[0048] Adjust the height of the laser emitter 5 from the calibration base 4 so that the center point of the laser emitter 5 is at the same height as the zero point on the optical plane projection scale 3.

[0049] Make the laser emitter 5 work to emit a laser plane;

[0050] Adjust the spatial position of the laser emitter 5 so that the laser plane can pass through the gap of the optical plane calibration block 1 and be projected onto the optical plane projection scale 3;

[0051] Adjust the position of the laser emitter 5 so that the distance of the laser line formed on the optical plane projection scale 3 from the zero point is the same;

[0052] After the above steps are completed, the calibration of the laser emitter is completed, that is, the calibration of the optical plane is completed.

[0053] Adjust the height of the center point of the camera 6 from the calibration base 4 so that it is at the same height as the zero point on the optical plane projection scale 3

[0054] Make the camera 6 work;

[0055] Use the software of the camera 6 manufacturer or compatible software to observe the camera imaging. In this example, the Allied Vision 15923 camera and the Vimba viewer software are used.

[0056] Adjust the position of the camera 6 so that the camera 6 can form an image on the camera photosensitive plane through the camera photosensitive plane calibration block 2

[0057] Continue to adjust the position of the camera 6 so that the imaging is as close as possible to the center horizontal / vertical position of the camera's photosensitive plane (depending on whether the camera needs to be installed horizontally or vertically);

[0058] After the above steps are completed, the camera calibration is completed, that is, the calibration of the camera's photosensitive plane is completed.

[0059] Since the spatial relationship between all calibration blocks and the calibration base 4 is fixed, the spatial relationship between the optical plane and the camera's photosensitive plane is also fixed.

[0060] As can be seen from the above steps, the included angle θ between the designed optical plane and the camera's photosensitive plane, and the distance l between the designed laser emitter 5 and the camera 6 can both be calibrated directly or indirectly by this method, and the accuracy of θ and l can be ensured by the accuracy of machining and installation.

[0061] For most commercially available cameras through the software of the camera manufacturer, directly observe the imaging on the camera's photosensitive plane.

[0062] By achieving an ideal relationship between both the optical plane and the camera's photosensitive plane with the calibration base 4, confirm that the optical plane and the camera's photosensitive plane achieve an ideal spatial relationship. Embodiment 2:

[0063] The difference between this embodiment and Embodiment 1 lies in: calibrating the spatial relationship of other similar non-physical planes except for the optical plane and the camera's photosensitive plane.

[0064] If the camera is replaced with another laser emitter, it is possible to correct whether the light rays emitted by the two laser emitters intersect on the projection scale 3 of the optical plane, and measure the projection angle, so as to determine whether the installation angles of the two laser generators meet the design requirements.

[0065] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for calibrating the spatial relationship between an optical plane and a camera photosensitive plane, characterized in that , It is realized by a mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane. The mechanical calibration device for the spatial relationship between the optical plane and the camera photosensitive plane includes a calibration base (4), an optical plane calibration block (1), a camera photosensitive plane calibration block (2), and an optical plane projection scale (3) arranged on the calibration base (4). The optical plane calibration block (1) has a slit through which the laser beam emitted by the laser emitter (5) passes and projects the laser beam onto the plane projection scale (3). The laser emitter (5) is installed within the frame of the calibration base (4), and the laser beam emitted by the laser emitter (5) passes through the first light-transmitting hole of the frame and emits out. The camera photosensitive plane calibration block (2) enables the camera (6) to image the light beam projected by the laser emitter (5) on the optical plane projection scale (3) through the slit on the camera photosensitive plane calibration block (2). The camera (6) is installed within the frame and captures the light beam projected by the laser emitter (5) on the optical plane projection scale (3) through the slit on the camera photosensitive plane calibration block (2). The center point of the laser emitter (5) is at the same height as the zero point on the optical plane projection scale (3). The center point of the camera (6) is at the same height as the zero point on the optical plane projection scale (3). The spatial angle between the optical plane calibration block (1) and the camera photosensitive plane calibration block (2) is equal to the spatial angle between the optical plane formed by the laser beam and the camera photosensitive plane of the camera. The calibration process is as follows: Install the optical plane calibration block (1), the camera photosensitive plane calibration block (2), and the optical plane projection scale (3) on the calibration base (4) respectively. Calibrate the spatial relationship between the optical plane and the calibration base (4) through the optical plane calibration block (1) and the optical plane projection scale (3); calibrate the spatial relationship between the camera photosensitive plane and the calibration base (4) through the camera photosensitive plane calibration block (2); determine the spatial relationship between the optical plane and the camera photosensitive plane based on the spatial relationships between the optical plane, the camera photosensitive plane, and the calibration base (4).

2. The method for calibrating the spatial relationship between an optical plane and a camera photosensitive plane according to claim 1, characterized in that , The process of calibrating the spatial relationship between the optical plane and the calibration base (4) through the optical plane calibration block (1) and the optical plane projection scale (3) is as follows: The laser emitter (5) operates to make the laser beam emitted by the laser generator form a laser optical plane. Adjust the spatial position of the laser emitter (5) so that the optical plane where the laser is located passes through the slit of the optical plane calibration block (1) and projects onto the optical plane projection scale (3). Adjust the position of the laser emitter (5) so that the center point of the laser emitter (5) is at the same height as the zero point on the optical plane projection scale (3).

3. The method for calibrating the spatial relationship between an optical plane and a camera photosensitive plane according to claim 1, characterized in that , The process of calibrating the spatial relationship between the camera photosensitive plane and the calibration base (4) through the camera photosensitive plane calibration block (2) is as follows: Adjust the height of the center point of the camera (6) from the calibration base (4) so that the center point of the camera (6) is at the same height as the zero point on the optical plane projection scale (3). Enable the camera to capture the laser line projection formed on the optical plane projection scale (3) through the camera photosensitive plane calibration block (2) and image it on the camera photosensitive plane. Continue to adjust the position of the camera (6) so that the imaging is at the center horizontal or vertical position of the camera's photosensitive plane.

4. The method for calibrating the spatial relationship between an optical plane and a camera photosensitive plane according to claim 1, characterized in that , Determine the spatial relationship between the light plane and the camera's photosensitive plane through the spatial relationship between the light plane and the camera's photosensitive plane and the calibration base (4). The process is as follows: If a laser line projection cannot be formed on the light plane projection scale (3), it proves that the spatial relationship between the light plane and the calibration base (4) is incorrect, and the attitude of the laser generator needs to be adjusted; If a laser line is formed on the light plane projection scale (3), but the scale reading is too high or too low, it proves that the spatial relationship between the light plane and the calibration base (4) is incorrect in one direction, and the attitude of the laser generator needs to be adjusted; Observe the camera imaging: If the camera cannot capture the laser line projection formed on the light plane projection scale (3) through the camera photosensitive plane calibration block (2) and image it on the camera's photosensitive plane, it proves that the spatial relationship between the camera's photosensitive plane and the calibration base (4) is incorrect, and the position of the camera needs to be adjusted; If the imaging on the camera's photosensitive plane is not in the exact middle of the camera's photosensitive plane, it proves that the spatial relationship between the camera's photosensitive plane and the calibration base (4) is incorrect, and the position of the camera (6) needs to be adjusted.

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