CN110125662B - Automatic assembling system for sound film dome - Google Patents

Automatic assembling system for sound film dome Download PDF

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CN110125662B
CN110125662B CN201910209005.8A CN201910209005A CN110125662B CN 110125662 B CN110125662 B CN 110125662B CN 201910209005 A CN201910209005 A CN 201910209005A CN 110125662 B CN110125662 B CN 110125662B
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dome
camera
film
voice
image
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CN110125662A (en
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曹衍龙
吴佳玲
杨将新
曹彦鹏
许宝杯
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Shandong Industrial Technology Research Institute of ZJU
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Shandong Industrial Technology Research Institute of ZJU
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/001—Article feeders for assembling machines
    • B23P19/007—Picking-up and placing mechanisms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/04—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes for assembling or disassembling parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
    • B23P19/00—Machines for simply fitting together or separating metal parts or objects, or metal and non-metal parts, whether or not involving some deformation; Tools or devices therefor so far as not provided for in other classes
    • B23P19/10—Aligning parts to be fitted together

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  • Mechanical Engineering (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The automatic assembling system for the sound film dome comprises a three-axis motion system, wherein a vacuum chuck on a manipulator grabs the dome, moves to a sound film photographing position to obtain a sound film image, calculates a sound film position angle parameter, then moves to the dome photographing position to obtain a dome image, calculates a dome position angle parameter, judges the sound film and dome position angle parameter, rotates the dome if the sound film and dome position angle parameter are not equal, obtains the dome image again, calculates the dome position angle parameter, judges whether the angle parameter is equal again, calculates the relative position of the dome sound film if the angle parameter is equal, executes an assembling program, and finally moves to a safe position. The invention fits the sound film-spherical top rectangular frame based on the image processing of the bilateral telecentric lens, perfects the error of the system, improves the image processing capability of the camera, can greatly reduce the requirement of the system on the precision of mechanical equipment, and greatly improves the assembly precision of the system to about 0.03mm, thereby realizing the assembly precision requirement of the system.

Description

Automatic assembling system for sound film dome
Technical Field
The invention relates to the field of visual inspection, in particular to a system for automatically assembling a sound film and a dome by using a bilateral telecentric lens.
Background
Nowadays, electronic products are more and more widely applied, and especially, accessories of the electronic products, such as sound films, ball tops and the like, need to be assembled by pure hands due to the fine accessories, but the pure hand assembly has the disadvantages of high labor intensity, low efficiency, frequent mistake in the assembly process and very low product yield.
The fine accessories are assembled by means of visual positioning, the image acquisition performance of the camera is improved by means of perfect system error calibration, and the requirement of the system on the precision of mechanical equipment can be greatly reduced, so that the assembly precision of the system is improved.
The imaging model of the camera is to use a mathematical formula to depict the whole imaging process, namely the geometric transformation relation between the space point of the object to be shot and the imaging point of the picture.
In general, camera imaging can be divided into four steps: rigid body transformation (from world to camera coordinate system), perspective projection (from camera to ideal image coordinate system), distortion correction (from ideal to real image coordinate system), and digitized images (from real to digitized image coordinate system).
World coordinate system: the absolute coordinate system of the objective three-dimensional world is also called an objective coordinate system. Because the digital camera is placed in a three-dimensional space, we need the reference coordinate system of the world coordinate system to describe the position of the digital camera, and use it to describe the position of any other object placed in the three-dimensional environment, and its coordinate values are represented by (X, Y, Z).
Camera coordinate system (optical center coordinate system): the coordinate values are expressed by (Xc, Yc, Zc) with the optical center of the camera as the origin of coordinates, the X-axis and the Y-axis being parallel to the X-axis and the Y-axis of the image coordinate system, respectively, and the optical axis of the camera as the Z-axis.
Image coordinate system: the coordinate values are expressed by (X, Y) with the center of the CCD image plane as the origin of coordinates and the X-axis and the Y-axis parallel to two vertical sides of the image plane, respectively. The image coordinate system is the representation of the location of a pixel in an image in physical units (e.g., millimeters).
Pixel coordinate system: the coordinate values are expressed by (u, v) with the vertex of the upper left corner of the CCD image plane as the origin and the X-axis and the Y-axis parallel to the X-axis and the Y-axis of the image coordinate system, respectively. The images acquired by the digital camera are first formed into a standard electrical signal and then converted into digital images by analog-to-digital conversion. The storage form of each image is an array of M × N, and the numerical value of each element in the image of M rows and N columns represents the gray scale of the image point. Each element is called a pixel, and the pixel coordinate system is an image coordinate system taking the pixel as a unit.
For camera calibration, the existing relatively universal and mature technology is a Zhang-Yong calibration algorithm for a pinhole camera model, internal and external parameters of a camera can be calibrated through a checkerboard calibration board, and calibration functions of an MATLAB tool box and an OpenCV can realize the calibration process.
And these camera calibration algorithms can only be used for normal shots.
The closer a normal pinhole camera target object is to the lens (the shorter the working distance), the larger the image is. When using a general lens for visual recognition, there are problems as follows: 1. the different magnifications are caused by the fact that the measured objects are not on the same measuring plane. 2. The lens distortion becomes large. 3. There is parallax, i.e. as the object distance becomes larger, the magnification of the object also changes. 4. The resolution of the shot is not high. 5. Uncertainty in the position of the image edges due to the geometry of the visual light source.
For a robotic system with vision, all the information obtained by the camera is described in the camera coordinate system. The first step of the robot is to determine the mutual position relationship between the camera coordinate system and the robot according to the information obtained by the vision system, which is the research content of the calibration of the robot hand and eye.
For the hand-eye calibration of the robot, the mechanical arm directly moves at two positions in space, and the calibration plate can be seen at the two positions. Then, a spatial transformation loop AX ═ XB is constructed, and the hand-eye relationship is obtained.
The robot system is a three-axis moving machine tool, can only translate in xyz three directions, and cannot realize any motion in space like a mechanical arm of a robot, so that the mutual position relationship between a camera and the machine tool cannot be calibrated by using a Zhang friend.
According to the motion characteristic that the machine tool can only translate, the relative relation between the camera and the platform can be calibrated in a mode of translating the platform. A more classical self-calibration method is to place a known reference object on the platform, translate the platform three times in three non-coplanar directions by control, obtain platform motion data from the controller, and then shoot the reference object by the camera to calculate the resulting camera motion. The rotation matrix of the camera and platform coordinate system in three-dimensional space can be obtained by the following formula:
tp＝Rtc
in the formula, tpVector formed by three orthogonal translations of the platform, tp＝(tp1,tp2,tp3)；tcFor the calculated vector t composed of three times of translation of camerac＝(tc1,tc2,tc3). But t ispAnd tcParameters which can be obtained only by a common lens, if other lenses are used, the lens t cannot be determinedpAnd tcThereby causing the camera calibration to be impossible. In addition, at present, for calibration of vision and machines, two-dimensional coordinate system conversion is considered, so that a lot of installation errors are ignored, and the calibration precision is not high.
Disclosure of Invention
The invention aims to provide an automatic voice diaphragm dome assembling system which can use a bilateral telecentric lens to collect images, accurately calibrate a camera and a machine tool with the bilateral telecentric lens and accurately calibrate the camera and the machine tool so that the assembling precision reaches a micron level.
An automatic voice diaphragm dome assembling system comprises a machine tool, a dome camera and a voice diaphragm camera, wherein a voice diaphragm placing station and a dome placing station are arranged on the machine tool, the machine tool is provided with a mechanical hand capable of obtaining a dome, a grabbing part of the mechanical hand is a sucker, the machine tool drives the mechanical hand to translate along an X axis, a Y axis and/or a Z axis, the mechanical hand rotates around the Z axis, the dome camera shoots the dome and/or the mechanical hand from bottom to top, and the voice diaphragm camera shoots a machine tool table top and/or a voice diaphragm from top to bottom; the mechanical arm and the voice film camera are relatively fixed and move synchronously; the automatic assembly performs the following steps:
the machine tool drives the mechanical arm to move to a ball top tool position to grab the ball top; moving a sound film camera to the position above a sound film station, photographing the sound film to obtain a sound film image, and obtaining pixel coordinates of characteristic points of a sound film frame and the sound film frame in the sound film image; enabling a machine tool to drive a mechanical arm with a dome to move and keep above a dome camera, shooting by the dome camera to obtain a dome image, and obtaining pixel coordinates of a dome frame and feature points of the dome frame in the dome image, wherein the feature points of the dome frame and the feature points of the sound film frame have an assembly corresponding relation; the assembly correspondence is that when the sound film and the dome are assembled, the dome border feature point and the sound film border feature point have a one-to-one correspondence, for example, the midpoint of the dome border coincides with the midpoint of the sound film border, the midpoint of the upper edge line of the dome border coincides with the midpoint of the upper edge line of the sound film border, where the upper direction refers to the position correspondence of the dome border line and the sound film border line, and does not represent an absolute orientation.
And aligning the sound film frame of the sound film image with the dome frame of the dome image, judging whether the sound film frame and the dome frame meet the installation requirements, if so, carrying out the next operation, and if not, obtaining the rotation angle required by smooth installation of the dome and the sound film, wherein the rotation angle is the rotation angle of the manipulator around the Z axis.
Converting the pixel coordinates of the characteristic points of the voice film frame into voice film coordinates of a voice film camera under a machine tool coordinate system, wherein the conversion relation is as follows: w _ file ═ R _ file ^ (-1) × A _ file ^ (-1) × uv _ file (rotation matrix)
Figure BDA0001999901610000041
Internal reference matrix
Figure BDA0001999901610000042
) (ii) a Converting the pixel coordinates of the characteristic points of the spherical top frame into the spherical top coordinates of the spherical top camera in a machine tool coordinate system, wherein the conversion relationship is as follows: w _ dome ^ R _ dome (-1) ^ A _ dome ^ (-1) ^ uv _ dome (rotation matrix)
Figure BDA0001999901610000043
Internal reference matrix
Figure BDA0001999901610000044
) (ii) a And calculating vector differences delta x and delta y of the dome camera and the voice film camera in a machine tool coordinate system, wherein the vector differences represent the relative positions of the voice film camera and the dome camera.
And the machine tool controls the manipulator to move delta x and delta y according to the vector difference, so that the manipulator translates along the Z axis, the dome is contacted with the sound film, and the manipulator releases the dome.
Further, the method for obtaining the voice diaphragm borders in the voice diaphragm image comprises the following steps:
step 1, carrying out gray image processing on a picture acquired by a voice film camera and a picture acquired by a dome camera;
step 2, extracting a rectangular region of interest from the picture acquired by the voice film camera and the picture acquired by the dome camera, thereby acquiring a rectangular region of interest (ROI);
step 3, after carrying out graying image processing on the picture acquired by the voice film camera and the picture acquired by the dome camera, carrying out binarization processing on the acquired graying images to prepare for extracting a rectangular frame;
step 4, a plurality of noise points exist in the binary image of the voice film camera and the binary image of the dome camera, a connected domain with a small black area is removed by using an OpenCV writing algorithm, the image is subjected to open operation, and the core of the open operation is defined to be in negative correlation with the threshold value of the binary image, so that burrs are removed;
step 5, Canny edge detection is carried out on the image after the opening operation, hough line transformation is carried out, and each line segment is drawn in the image in sequence;
and 6, solving a minimum envelope rectangle of the Hough line segment graph through a minAreaRect function provided by OpenCV, and drawing rectangular frames of parts to be assembled in the original images of the sound film camera and the dome camera.
Further, the method for obtaining the rotation angle of the manipulator around the Z axis comprises the steps of obtaining the center coordinate of the sound film frame, taking the center coordinate as an original point, and recording the machine tool coordinate (X) when the sound film is shot, wherein the line between the original point and the corner point of the sound film frame and the sound film deflection angle theta 1 of the X axis or the Y axis1,y1) (ii) a Obtaining the central coordinate of the ball top frame, and the ball top deflection angle theta 2 between the connecting line of the central coordinate as the original point and the angular point of the ball top frame and the X axis or the Y axis, and recording the machine tool coordinate (X) when shooting the ball top2,y2) (ii) a Converting the pixel coordinates of the characteristic points of the dome frame into a machine tool coordinate system, converting the pixel coordinates of the characteristic points of the sound film frame into the machine tool coordinate system, enabling the center of the sound film frame to coincide with the center of the dome frame, and calculating the difference value of the deflection angle of the sound film and the deflection angle of the dome, wherein the difference value is the rotation angle of the mechanical hand around the Z axis.
Further, the method for calculating the relative position of the dome sound film comprises the following steps:
the machine coordinates (x ', y') of the diaphragm are:
x′＝xc1+x1
y′＝yc1+y1；
the machine coordinates (x ", y") of the dome are:
x″＝xc2+Δx+x0
y″＝yc2+Δy+y0；
the relative position of the dome voice diaphragm (dx, dy) is therefore:
dx＝x′-x″＝xc1+x1-(xc2+Δx+x0)；
dy＝y′-y″＝yc1+y1-(yc2+Δy+y0)。
further, the machine tool comprises a base four-axis precision moving assembly platform, a mechanical arm, a sound film image acquisition assembly, a ball top image acquisition assembly, a sound film tool module and a ball top tool module; the four-axis precision moving assembly platform comprises a sound film image acquisition assembly, a ball top image acquisition assembly, a sound film tool module and a ball top tool module, wherein the sound film tool module and the ball top tool module are arranged on a base.
Further, the four-axis precision moving assembly platform comprises an X-axis guide rail, a Y-axis guide rail and a Z-axis guide rail; the X-axis guide rail is fixed on the base, the Y-axis guide rail is movably arranged on the X-axis guide rail, and the Z-axis guide rail is movably arranged on the Y-axis guide rail; the Z-axis guide rail is provided with a slide block, and the slide block is provided with a manipulator and a voice film camera.
Furthermore, the sound film camera is matched with a sound film light source, and/or the dome camera is matched with a dome light source.
Further, the manipulator includes the bed frame, vacuum chuck and pivot, and vacuum chuck sets up in pivot one end and coaxial with the pivot, and bed frame and sound membrane camera relatively fixed, the pivot sets up in the bed frame, and the pivot links to each other with the rotary driving piece.
The invention has the advantages that:
1. the sound film-dome rectangular frame is fitted based on image processing of the bilateral telecentric lens, so that errors existing in the system are improved, the image processing capacity of the camera is improved, the requirement of the system on the precision of mechanical equipment can be greatly reduced, the assembly precision of the system is greatly improved to about 0.03mm, and the assembly precision requirement of the system is met.
Description of the drawings:
FIG. 1 is a schematic diagram of the present invention.
Fig. 2 is a process diagram of the automatic assembly of the dome diaphragm.
Fig. 3 is a double-sided telecentric lens path.
Fig. 4 is a measurement accuracy table for telecentric lenses of different distortion camera models.
Fig. 5 is a virtual checkerboard coordinate graph.
FIG. 6 is a graph of virtual checkerboard pixel coordinates.
Fig. 7 is a graph of the sound diaphragm picture in graying + ROI extraction.
Fig. 8 is a sound membrane binarization map.
Fig. 9 is a diagram of on operation + hough line transformation of a voice diaphragm picture.
Fig. 10 is a block diagram of extracted sound diaphragm rectangles.
FIG. 11 is a block diagram of an extracted dome rectangle.
Fig. 12 is an assembly view of the voice diaphragm dome.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not a whole embodiment. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment provides a visual inspection technology of an automatic voice diaphragm-dome assembling system based on a bilateral telecentric lens.
As shown in figure 1, including the triaxial moving system, triaxial moving system (1) includes the X axle, Y axle and Z axle, the Z axle is equipped with the manipulator and has sound membrane subassembly (3) of shooing, sound membrane subassembly (3) of shooing includes the sound membrane camera, telecentric lens and light source, manipulator (2) are equipped with vacuum chuck (4), Z axle below is equipped with the platform, the platform has the sound membrane and places district (5) and place district (6) and lie in the dome subassembly (7) of shooing of platform below in the dome on its right side, the dome subassembly of shooing includes the dome camera, telecentric lens and light source, dome subassembly (7) of shooing are located platform (8) below and are shot to the top.
In this embodiment, the audio film camera and the dome camera both use 500 ten thousand pixels industrial cameras, which can ensure sufficient viewing field (30mm × 30mm) and high resolution (about 0.009 mm/pixel), and both use telecentric lenses.
In the common pinhole camera widely used at present, the closer a target object is to a lens (the shorter the working distance is), the larger an image is formed. When using a general lens for visual recognition, there are problems as follows: the measured object is not on the same measuring plane, so that the magnification is different, the distortion of the lens is large, the parallax exists, namely, when the object distance is large, the magnification of the object is changed, the resolution of the lens is not high, and the uncertainty of the image edge position is caused by the geometric characteristic of the visual light source.
The telecentric lens used by the film camera and the dome camera can obviously reduce the distortion of the imaging system, provides hardware guarantee for micron-level detection precision, and simultaneously the imaging system also has the advantage of large depth of field, ensures that the image has stable definition and magnification factor, and ensures the stability of data acquisition.
As one embodiment, the mechanical arm and the voice film camera are simultaneously arranged on a lifting plate, the lifting plate is fixed on a Z-axis guide rail, a hole is formed in the platform, the ball top photographing assembly is located below the hole and below the platform, and the ball top photographing assembly photographs images towards the upper side of the platform.
The holes are provided with glass plates, and the shape of the holes can be regular or irregular such as square, rectangle and the like, and the shape of the holes is generally circular.
The dome camera sees through glass and shoots upwards, and mounting glass is in order to prevent that the foreign matter from dropping into the hole, and the influence is shot, and the light source among the sound membrane subassembly of shooing adopts the parallel blue light of bar low angle, can accurately discern the sound membrane crease to disturb with other light and distinguish.
As an implementation mode, a light source in the dome shooting assembly adopts a coaxial light mode, the contour of the dome can be accurately identified by adopting the coaxial light mode, the position of the dome needs to be adjusted to a proper position so as to be assembled with a voice diaphragm, the adjustment mode adopts an iterative convergence calculation method, and the new value is continuously calculated by repeatedly operating the old value recursion of the variable.
In the embodiment, a double-side telecentric lens is used, and the magnification of an obtained image is not changed within a certain object distance range, so that the image shot by the lens has no near-far relationship, as shown in fig. 3, the light path of the double-side telecentric lens is shown, in the figure, u is the object distance, v is the image distance, f1 and f2 are the focal lengths of the two lenses, and a diaphragm is placed at the focal points of the two lenses, so that light rays entering and exiting the lenses are parallel light rays, and the rest of the light rays are blocked by the diaphragm.
The bilateral telecentric lens has the characteristic that the magnification factor is not influenced when an object is far or a camera is far, so that the bilateral telecentric lens is widely applied to the field of machine vision measurement and detection. Unlike perspective projection of a pinhole camera, a telecentric lens performs orthogonal projection, which produces a different geometric model of projection than a pinhole camera, and therefore many existing calibration methods are not suitable for telecentric lenses.
Machine tool-camera angular deviation calibration is in traditional industrial production, generally neglects the installation declination of a camera, but in order to realize the precise assembly of small parts such as a sound film and a dome, the precision requirement is in the micron level, and the camera cannot be guaranteed to be accurately vertical to a platform only by manual installation, so the installation declination between the machine tool and the camera needs to be obtained through calibration, and the rear positioning detection precision is guaranteed.
As an embodiment, for a robot system with vision, all information obtained by a camera is described in a camera coordinate system, the robot is required to obtain information according to the vision system, the first step is to determine the mutual position relationship between the camera coordinate system and the robot, for hand-eye calibration of the robot, a mechanical arm is directly moved to two positions in space, a calibration plate is ensured to be seen in the two positions, and then a space transformation loop AX XB is constructed, so that the hand-eye relationship can be obtained.
In this embodiment, since the automatic assembling device for the sound diaphragm-dome is a three-axis moving machine tool, it can only translate in three directions of x, y and z, and cannot realize any movement in space like the mechanical arm of a robot, so the method cannot be used to calibrate the mutual position relationship between the machine tool and the camera.
As an embodiment, generally, according to the motion characteristic that a machine tool can only translate, a relative relationship between a camera and a platform is calibrated by translating the platform, and a more classical self-calibration method is to place a known reference object on the platform, translate the platform three times along three non-coplanar directions by controlling the platform, obtain platform motion data from a controller, shoot the reference object by the camera to calculate the induced camera motion, and obtain a rotation matrix of a coordinate system of the camera and the platform in a three-dimensional space by a vector formed by three orthogonal translations of the platform and a vector formed by three translations of the camera.
The embodiment adopts the double-side telecentric lens, the imaging of the double-side telecentric lens does not have big or small distance, so the external parameters of the telecentric lens cannot be determined, and the translation vector of the camera cannot be obtained, so the method cannot be used for calibration.
At present, for calibration of vision and machines, two-dimensional coordinate system conversion is considered, a lot of installation errors are ignored, and the calibration precision is not high.
The automatic assembling device in the embodiment has high precision requirement on precision assembly, so that a calibration method for establishing a spatial three-dimensional coordinate system conversion relation is provided, and the camera model adopted in the embodiment is BT-2324.
The voice film camera and the manipulator are mounted on the Z-axis guide rail and can move up and down along the Z-axis guide rail, so that the fixed calibration point is taken on the platform.
As shown in fig. 2, the automatic voice diaphragm dome assembling system performs the following steps:
step 1, a three-axis motion system drives a mechanical arm, a dome fixture position on a fixture platform grabs a dome through a vacuum chuck on the mechanical arm, the dome is moved to a sound film photographing position, and a sound film camera photographs from top to bottom to obtain a sound film image;
step 2, reading a sound film image obtained by a sound film camera by a computer control system, and calculating a sound film position angle parameter;
step 3, the three-axis motion system drives the ball top grabbed by the vacuum chuck on the manipulator to move to a ball top photographing position, and a ball top camera photographs from bottom to top to obtain a ball top image;
step 4, reading a dome image obtained by the dome camera by the computer control system, and calculating a dome position angle parameter;
step 5, judging whether the sound film position angle parameter is equal to the dome position angle parameter, if so, calculating the relative position of the dome sound film, if not, rotating the dome, acquiring the dome image again, calculating the dome position angle parameter, and judging whether the angle parameters are equal again;
and 6, moving to an assembly position, executing an assembly program, and finally moving to a safety position.
As an implementation mode, establishing a camera model for a voice film camera and a dome camera based on a double-sided telecentric lens, and obtaining a conversion relation between a world coordinate system and a pixel coordinate system based on the established camera model; the purpose of the established camera imaging model is to enable the camera to carry out the work in the visual detection fields of photographing, image recognition, scanning and the like; the coordinate system of the camera model includes: world coordinate system (XwYwZw), camera coordinate system (XcYcZc), image coordinate system (xy), and pixel coordinate system (uv).
The camera model established by the invention comprises:
1. establishing a distortion-free camera model;
2. converting the three-dimensional world coordinate system (XwYwZw) into a camera coordinate system (XcYcZc);
3. converting the camera coordinate system (XcYcZc) to an image coordinate system (xy);
4. converting the image coordinate system (xy) into a two-dimensional pixel coordinate system (uv);
5. calibrating the parameters by using a marking plate to establish a distortion-free camera model;
6. a camera model with distortion is built according to a standard pixel coordinate calculation formula considering distortion.
Preferably, the conversion of the world coordinate system to the camera coordinate system is a rotation + translation process, and the conversion matrix is expressed as follows:
Figure BDA0001999901610000091
preferably, the conversion of the camera coordinate system to the image coordinate system is an imaging process of the camera, and the conversion matrix is expressed as follows:
Figure BDA0001999901610000101
preferably, the conversion of the image coordinate system to the pixel coordinate system is a unit conversion, and the conversion matrix is expressed as follows:
Figure BDA0001999901610000102
preferably, the transformation matrix (4.1), the transformation matrix (4.2) and the transformation matrix (4.3) are multiplied together to obtain the transformation relation between the world coordinate system and the pixel coordinate system:
Figure BDA0001999901610000103
the calibration board is used for calibrating the parameters of the camera, the calibration board used by the invention is a checkerboard calibration board, the size of each check is 1mm, the calibration method can calibrate the internal and external parameters of the camera by only shooting one checkerboard, and the image coordinate system of the checkerboard calibration board is obtained according to a formula (4.2):
Figure BDA0001999901610000104
preferably, equation (4.5) is written in the form of a matrix multiplication:
Figure BDA0001999901610000105
preferably, the vector consisting of the internal and external parameters on the left side of the equation of the formula (4.6) is required to be solved, and the vector consists of five unknowns, so that at least 5 equations are required to solve all unknowns; in order to ensure the accuracy of the calculation result, 88 angular points are selected from the checkerboard, and the following equation is formed:
Figure BDA0001999901610000111
preferably, the dimension of the coefficient matrix on the left side of the above equation is 88 × 5, and the number of equation sets is much larger than 5, so that the equation is converted into the solution of the over-determined equation:
ML＝X (4.8)
the solution of the overdetermined equation satisfies the general equation:
MTML＝MTX (4.9)
the vector L is found by converting the general equation (4.9) as follows:
L＝(MTM)-1MTX (4.10)
and calculating the camera magnification m by combining the rotation component and the translation component obtained by calculation with a formula (4.2):
Figure BDA0001999901610000112
and solving to obtain the internal and external parameters of the camera.
Figure BDA0001999901610000113
Preferably, a distorted camera model is established, and the telecentric lens mainly has three distortion types, namely radial distortion, eccentric distortion and thin prism distortion. In order to ensure the calibration accuracy, a distorted camera model considering lens distortion is established, wherein k1 is a radial distortion coefficient, h1 and h2 are eccentric distortion coefficients, s1 and s2 are thin prism distortion coefficients, and xu,yuPixel coordinates, x, calculated for a previous undistorted camera modeld,ydTo consider the standard pixel coordinates after distortion, the following is a standard pixel coordinate calculation formula that considers distortion:
Figure BDA0001999901610000114
Figure BDA0001999901610000115
when converting pixel coordinates into camera coordinates, the pixel coordinates use (x)d,yd)。
Nonlinear optimization of the distorted camera model:
by solving the minimum value of the reprojection error, an objective function is established, and internal and external parameters and distortion coefficients are iteratively optimized, wherein the objective function is as follows:
Figure BDA0001999901610000121
in the formula piIs the pixel coordinates of a picture taken by the camera,
Figure BDA0001999901610000122
is the pixel coordinate calculated by the undistorted camera model established by the formulas (4.4) and (5.1). The above equation is iteratively optimized by the Levenberg-Marquardt (LM) algorithm. The initial values of the rotation and translation parameters are obtained by solving the front undistorted camera model, and the initial value of the lens distortion parameter is 0.
The LM algorithm is different from the Gauss-Newton optimization algorithm in some aspects, and the iteration formula of the Gauss-Newton method is as follows:
Figure BDA0001999901610000123
Figure BDA0001999901610000124
first derivative of each variable for the objective function, Hf(xn)-1Representing the derivative directly in the gradient vector. The product of these two quantities is the step size Δ for each iteration, which is rewritten as a matrix multiplication:
Δ＝-(Jf T.Jf)-1.Jf T.f (6.3)
wherein g is 2Jf TF is Jacobian matrix, H ≈ 2JfT .JfIs a Hessian matrix.
The LM algorithm is characterized in that an adjustable damping parameter lambda is added on the basis of a Gauss-Newton method, and the iteration step length delta k is as follows:
Δk＝-(Jf T.Jf+λ)-1.Jf T.f (6.4)
in the LM method, the rule of taking increments is as follows:
the initial value of λ is set to 0.0001, and if the solution of the incremental equation, Δ k, reduces the objective function f, this λ is accepted and replaced with λ/10 in the next iteration. If the incremental equation corresponding to the value of λ is solved by Δ k such that f is increased, then this λ is discarded and replaced with a 10 λ re-solved incremental equation. And repeating the steps until f is reduced.
LM has the advantages of both Newton's method and gradient method. When λ is small, the step size is equal to newton's method step size, and when λ is large, the step size is approximately equal to that of the gradient descent method.
Obtaining calibration results of different phase machine models:
Figure BDA0001999901610000125
Figure BDA0001999901610000131
obtaining the measurement precision of telecentric lenses of different distortion camera models:
Figure BDA0001999901610000132
as an embodiment, the calibration method of the machine tool-camera angle deviation comprises the following steps: and installing an automatic assembly system, wherein the automatic assembly system comprises a three-axis motion system and a platform, the three-axis motion system and the platform form a machine tool, the voice film camera is installed on the three-axis motion system, a fixed mark point p on the platform is selected, and a machine tool coordinate system with the fixed mark point as an original point is established.
In the steps of the embodiment, a fixed mark point is marked as p1, a three-axis motion system is controlled to move, a virtual checkerboard is established, and machine tool coordinates of the virtual checkerboard with the fixed mark point as an origin are obtained; meanwhile, the voice film camera shoots the fixed mark points to obtain a plurality of continuous pictures.
In step 2 of this embodiment, the three-axis motion system is controlled to make the camera form a virtual checkerboard with a size of 4 × 3 on the spatial plane, the size of the square is 1mm, and as shown in fig. 4, the machine coordinates of the fixed mark points are obtained according to the machine coordinates of the virtual checkerboard; and obtaining the pixel coordinates of the fixed mark points according to a plurality of continuous pictures.
In step 3 of this embodiment, since the motions are opposite, the machine coordinates of the mark point p1 and the machine coordinates of the virtual checkerboard are symmetric about the origin, so as to obtain the machine coordinates of the mark point p1, and the camera tracks and shoots the mark point p1 once every time the three-axis motion system moves one step, it is required to ensure that the mark point p1 is all within the camera field of view, and the three-axis motion system moves 12 steps, so as to obtain 12 consecutive pictures containing the mark point p 1.
In the present embodiment, the method of obtaining the pixel coordinates of the marker point p1 is: firstly, extracting the image edge of the checkerboard picture through a canny operator, then extracting the straight line of the image edge by using a Hough algorithm, filtering the detection result of the corner points of the whole picture by using the intersection of the straight lines, and finally, automatically, reliably and accurately extracting the corner point coordinates of the checkerboard in all the pictures so as to obtain the pixel coordinate of the mark point p1, as shown in fig. 5 and 6.
And converting the pixel coordinates of the fixed mark points into a camera coordinate system through an internal reference matrix of the voice film camera to obtain the camera coordinates of the fixed mark points.
In step 4 in this embodiment, the expression of the reference matrix of the voice diaphragm camera is:
Figure BDA0001999901610000141
wherein m is the multiplying power of the voice film camera, u is the object distance of the voice film camera, and v is the image distance of the voice film camera.
Establishing an over-determined equation, substituting the machine tool coordinates and the camera coordinates of the fixed mark points into the over-determined equation, solving to obtain a conversion matrix of a machine tool coordinate system and a camera coordinate system where the fixed mark points are located, wherein the specific relation of rotation and translation exists between the camera coordinates and the machine tool coordinates, and the conversion matrix is as follows:
Figure BDA0001999901610000142
writing the above equation in the form of a system of equations:
Xc＝r11Xt+r12Yt+tx
Yc＝r21Yt+r22Yt+ty (7.2)
in order to find out the rotation and translation parameters, it needs to be represented as a vector separately, so equation (7.2) can be converted into the following representation:
Figure BDA0001999901610000143
in the formula, the camera coordinates of the fixed mark point p1 are the machine coordinates of the mark point, and the camera coordinates, the machine coordinates of the mark point, are the rotation parameters, the translation parameters of the X axis and the translation parameters of the Y axis respectively.
In the above embodiment, the calibration of the machine tool-camera angle deviation is performed when the voice diaphragm camera moves and the mark point is fixed. As another embodiment, the method is used for the situation that the dome camera is fixed and the mark point moves.
As an embodiment, the calibration method of the machine tool-camera angle deviation comprises the following steps: and installing an automatic assembly system, wherein the automatic assembly system comprises a three-axis motion system and a platform, and the three-axis motion system and the platform form a machine tool.
The three-axis motion system is provided with a mechanical arm, the ball-top camera is arranged on the platform, and a moving mark point on the mechanical arm is selected; controlling the three-axis system to move, establishing a virtual checkerboard, and obtaining machine tool coordinates of the virtual checkerboard; and obtaining the machine tool coordinates of the mobile mark points according to the machine tool coordinates of the virtual checkerboard.
According to the embodiment of the step 1 and the step 2, the moving mark point is marked as p2, the moving mark point p2 is arranged at the tail end of the manipulator, when the three-axis motion system moves in a space plane to construct a virtual checkerboard, the camera shoots the moving mark point p2 once when the three-axis motion system moves by one step, and the machine coordinates of the virtual checkerboard are the machine coordinates of the moving mark point p2 because the moving mark point p2 moves along with the three-axis motion system.
The ball-top camera shoots the moving mark points to obtain a plurality of continuous pictures, and pixel coordinates of the moving mark points are obtained according to the plurality of continuous pictures.
According to step 3 of this embodiment, the method for obtaining the pixel coordinates of the moving marker point p2 adopted by this embodiment is as follows: the image edges of the checkerboard pictures are extracted through a canny operator, then straight lines of the image edges are extracted through a Hough algorithm, the detection results of the corner points of the whole picture are filtered through line intersections, and finally the corner point coordinates of the checkerboard pictures in all the images are automatically, reliably and accurately extracted, so that the pixel coordinates of the moving mark point p2 are obtained, as shown in fig. 5 and 6.
And converting the pixel coordinates of the moving mark points into a camera coordinate system through the internal reference matrix to obtain the camera coordinates of the moving mark points.
According to step 4 of this embodiment, the expression of the internal reference matrix is:
Figure BDA0001999901610000151
wherein m is the multiplying power of the camera, u is the object distance of the camera, and v is the image distance of the camera.
And establishing an over-determined equation, substituting the machine tool coordinates and the camera coordinates of the mobile mark points into the over-determined equation, and solving to obtain a conversion matrix of the machine tool coordinate system and the camera coordinate system where the mobile mark points are located.
According to step 5 of this embodiment, the expression of the transformation matrix is as follows:
Figure BDA0001999901610000161
in the formula (X)ci,Yci) To move the camera coordinates of the marker point, (X)ti,Yti) The machine coordinate i of the moving mark point is 1, 2, 3 … n; t is tx、tyTranslation parameters and rotation parameters, respectively.
The obtained camera coordinates and the machine tool coordinates have a rotation + translation relationship, and the conversion matrix is as follows:
Figure BDA0001999901610000162
writing equation (7.1) in the form of a system of equations:
Xc＝r11Xt+r12Yt+tx
Yc＝r21Yt+r22Yt+ty (7.2)
in order to find the rotation and translation parameters, the equation needs to be expressed as a vector separately, so equation (7.2) can be converted into the following expression:
Figure BDA0001999901610000163
in the formula (X)ci,Yci) To move the camera coordinates of the marker point, (X)ti,Yti) The machine coordinates of the moving mark point are i 1, 2, 3 … n; t is tx、tyRespectively, a translation parameter, r11、r12、r21、r22The coefficient matrix dimension to the left of equation (7.3) is 24 × 6, respectively, for the rotation parameters.
The camera-camera assembly has errors, so the camera-camera relative position calibration method needs to calibrate the camera-camera relative position, and comprises the following steps: installing an automatic assembly system, wherein the automatic assembly system comprises a three-axis motion system and a transparent platform, the three-axis motion system and the transparent platform form a machine tool, two marked cameras are respectively a voice film camera and a dome camera, a film camera is installed on the three-axis motion system, the dome camera is installed on the transparent platform, and a transparent mark plate is placed on the transparent platform; and shooting the mark plate downwards by the film camera, and shooting the mark plate upwards by the dome camera to obtain checkerboard pictures shot by the film camera and the dome camera, and recording the checkerboard pictures as a film checkerboard picture and a dome checkerboard picture respectively.
Extracting the checkerboard angular points of the film checkerboard picture and the dome checkerboard picture, obtaining pixel coordinates of the film checkerboard angular points and the dome checkerboard angular points, respectively calculating rotation matrixes of the film camera, the dome camera and the machine tool, converting the pixel coordinates of the respective checkerboard angular points into a machine tool coordinate system through the conversion matrixes, and obtaining machine tool coordinates of the film checkerboard angular points and the dome checkerboard angular points.
Selecting a plurality of corresponding corner points of the machine tool coordinates of the film camera and the dome camera, establishing a film camera coordinate vector and a dome camera coordinate vector, and obtaining the relative positions delta x and delta y between the film camera and the dome camera.
In this embodiment, Δ x, Δ y are obtained by: the film camera coordinate vector and the dome camera coordinate vector have n dimensions, the dimensions of the two cameras are the same, the difference between the corresponding dimensions of the film camera coordinate vector and the dome camera coordinate vector is solved, the differences of all the corresponding dimensions are summed, and finally, the average is calculated, namely delta x and delta y.
In this embodiment, the dimension of the film camera coordinate vector and the dome camera is 1 × 16, taking solving Δ x and Δ y as an example, summing the parameters in the vector through a sum function, and then dividing by the number of corner points to obtain Δ x and Δ y, which are the coordinate difference of the two cameras in the x direction, and the solving method of Δ x and Δ y is the same.
As another embodiment, a method for calibrating a relative position between a camera and a camera includes the following steps: installing an automatic assembly system, wherein the automatic assembly system comprises a three-axis motion system and a transparent platform, the two marked cameras are respectively a film camera and a dome camera, the film camera is installed on the three-axis motion system, the dome camera is installed on the platform, and a transparent picture with a marker is placed on the transparent platform; and shooting the mark plate downwards by the film camera, and shooting the mark plate upwards by the dome camera to obtain checkerboard pictures shot by the film camera and the dome camera, and recording the checkerboard pictures as a film checkerboard picture and a dome checkerboard picture respectively.
Image preprocessing is carried out on the film checkerboard picture and the dome checkerboard picture to obtain a preprocessed picture, the pixel coordinates of feature points of the preprocessed picture are extracted, the pixel coordinates of the feature points are matched, and the pixel coordinates of corresponding feature points between the two pictures are obtained.
And then respectively calculating conversion matrixes of the film camera, the dome camera and the machine tool, converting the pixel coordinates of the corresponding feature points into a machine tool coordinate system through the conversion matrixes, obtaining machine tool coordinates of the corresponding feature points, and calculating the relative positions of the corresponding feature points in the machine tool coordinate system.
In the image processing of this embodiment, after the calibration of the relative position between the machine tool camera and the camera is completed, the two images of the voice diaphragm and the dome acquired by the film camera and the dome camera are processed.
An image processing method comprising the steps of: step 1, acquiring an image, carrying out graying processing on the image, and acquiring a grayed image; step 2, carrying out binarization processing on the gray level image to obtain an image after binarization processing; the purpose of binarization is to prepare for extracting a rectangular frame later; step 3, performing opening operation on the image subjected to the binarization processing to obtain an image subjected to opening operation; the value of the defined on operation is in negative correlation with the threshold value of binarization, so as to remove burrs; step 4, Canny edge detection is carried out on the image after the opening operation, hough line transformation is carried out, each line segment is drawn in the image in sequence, and a hough line segment image is obtained; and 5, solving the minimum envelope rectangle of the Hough line segment graph through a minAreaRect function, and drawing a rectangular frame in the original image to obtain the image rectangular frame.
The connected domain with a small black area in the binarized image is removed by using the OpenCV writing algorithm, because many noise still exists in the binarized image to affect the image quality, as shown in fig. 7.
And carrying out graying processing on the color sound film image, and after graying, carrying out binarization processing on the obtained grayscale image, wherein the purpose of binarization is to prepare for extracting a rectangular frame later. As shown in fig. 8, the picture after binarization is shown, and it can be seen that there are many noise points in the binarized image, and here, the connected domain with a small black area is removed by the OpenCV writing algorithm.
And performing an opening operation on the image, defining that the value of the opening operation is in negative correlation with a binary threshold value so as to remove burrs, then performing Canny edge detection on the image after the opening operation, performing hough line transformation, and sequentially drawing each line segment in the image, as shown in fig. 9.
The minAreaRect function provided by OpenCV finds the minimum bounding rectangle of the Hough line segment graph and draws a rectangular box in the original image, as shown in FIGS. 10 and 11.
In the method for verifying the assembling precision of the voice diaphragm dome, the assembling precision of the voice diaphragm dome is verified after the positions between a machine tool and a camera and between the camera and the camera are calibrated.
The method for verifying the assembling precision of the sound film and the dome comprises the following steps: step 1, recording machine tool coordinates (x) of film camera and dome camera during opposite shooting0,y0) (ii) a Step 2, the vacuum chuck sucks the dome, controls the three-axis motion system to move to the sound film shooting position, and records the machine tool coordinate (x) when the sound film is shot1,y1) (ii) a Step 3, obtaining a voice film image through the film camera, and processing the image to obtain the center coordinate (x) of the voice film rectangular framec1,yc1) And a declination angle θ 1; step 4, controlling the three-axis motion system to move to the top of the ball for shootingPosition, recording machine coordinates (x) when the dome is photographed2,y2) (ii) a Step 5, acquiring a dome image through the dome camera, and processing the image to obtain the central coordinate (x) of the dome rectangular framec2,yc2) And a declination angle θ 2; step 6, converting the sound film rectangular frame and the ball top rectangular frame into a machine tool coordinate system, calculating the deflection angle theta of the two rectangular frames, and calculating the central coordinate (x) of the ball top rectangular frame by controlling the rotation angle until the deflection angle theta is equal to the rectangular frame corner point of the sound film ball topc2,yc2) (ii) a And 7, calculating the relative positions of the dome and the sound film.
The machine coordinates (x ', y') of the diaphragm are:
x′＝xc1+x1
y′＝yc1+y1 (10.1)
the machine coordinates (x ", y") of the dome are:
x″＝xc2+Δx+x0
y″＝yc2+Δy+y0 (10.2)
the relative position (dx, dy) of the dome voice diaphragm is:
dx＝x′-x″＝xc1+x1-(xc2+Δx+x0)
dy＝y′-y″＝yc1+y1-(yc2+Δy+y0) (10.3)
and 8, moving the dome and the sound film to an assembly position for assembly, wherein the sound film is a picture after the dome is assembled as shown in fig. 12, and the assembly effect is very accurate. Through calculation, the assembling deviation of the sound film dome is approximately 3 pixels, the precision is about 0.03mm, and the assembling precision requirement of the system is met.
The invention has the advantages that the sound film-spherical top rectangular frame is fitted based on the image processing of the bilateral telecentric lens, the error of the system is perfected, the image processing capability of the camera is improved, the requirement of the system on the precision of mechanical equipment can be greatly reduced, the assembly precision of the system is greatly improved to about 0.03mm, and the assembly precision requirement of the system is realized.
The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.
All patents and publications mentioned in the specification of the invention are indicative of the techniques disclosed in the art to which this invention pertains and are intended to be applicable. All patents and publications cited herein are hereby incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference. The invention described herein may be practiced in the absence of any element or elements, limitation or limitations, which limitation or limitations is not specifically disclosed herein. For example, the terms "comprising", "consisting essentially of … …" and "consisting of … …" in each instance herein may be substituted for the remaining 2 terms of either. The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described, but it is recognized that various modifications and changes may be made within the scope of the invention and the claims which follow. It is to be understood that the embodiments described herein are preferred embodiments and features and that modifications and variations may be made by one skilled in the art in light of the teachings of this disclosure, and are to be considered within the purview and scope of this invention and the scope of the appended claims and their equivalents.

Claims (8)

1. The automatic assembly system for the sound film dome is characterized by comprising a machine tool, a dome camera and a sound film camera, wherein the machine tool is provided with a sound film placing station and a dome placing station, the machine tool is provided with a mechanical hand capable of obtaining the dome, a grabbing part of the mechanical hand is a sucker, the machine tool drives the mechanical hand to translate along an X axis, a Y axis and/or a Z axis, the mechanical hand rotates around the Z axis, the dome camera shoots the dome and/or the mechanical hand from bottom to top, and the sound film camera shoots a machine tool table top and/or a sound film from top to bottom; the mechanical arm and the voice film camera are relatively fixed and move synchronously; the automatic assembly performs the following steps:
the machine tool drives the mechanical arm to move to a ball top tool position to grab the ball top; moving a sound film camera to the position above a sound film station, photographing the sound film to obtain a sound film image, and obtaining pixel coordinates of characteristic points of a sound film frame and the sound film frame in the sound film image; enabling a machine tool to drive a mechanical arm with a dome to move and keep above a dome camera, shooting by the dome camera to obtain a dome image, and obtaining pixel coordinates of a dome frame and feature points of the dome frame in the dome image, wherein the feature points of the dome frame and the feature points of the sound film frame have an assembly corresponding relation;
centering a sound film frame of the sound film image and a dome frame of the dome image, judging whether the sound film frame and the dome frame meet the installation requirements, if so, carrying out next operation, and if not, obtaining a rotation angle required by smooth installation of the dome and the sound film, wherein the rotation angle is the rotation angle of a manipulator around a Z axis;
converting the pixel coordinates of the characteristic points of the voice film frame into voice film coordinates of a voice film camera under a machine tool coordinate system, wherein the conversion relation is as follows:
W_film＝R_film^(-1)*A_film^(-1)*uv_film
wherein the rotation matrix
Figure FDA0002788184100000011
Internal reference matrix
Figure FDA0002788184100000012
Wherein m is the multiplying power of the voice film camera, u is the object distance of the voice film camera, and v is the image distance of the voice film camera;
converting the pixel coordinates of the characteristic points of the spherical top frame into the spherical top coordinates of the spherical top camera in a machine tool coordinate system, wherein the conversion relationship is as follows:
W_dome＝R_dome^(-1)*A_dome^(-1)*uv_dome
wherein the rotation matrix
Figure FDA0002788184100000013
Internal reference matrix
Figure FDA0002788184100000014
Wherein m is the multiplying power of the voice film camera, u is the object distance of the voice film camera, and v is the image distance of the voice film camera;
calculating vector differences delta x and delta y of the dome camera and the voice film camera in a machine tool coordinate system, wherein the vector differences represent the relative positions of the voice film camera and the dome camera;
and the machine tool controls the manipulator to move delta x and delta y according to the vector difference, so that the manipulator translates along the Z axis, the dome is contacted with the sound film, and the manipulator releases the dome.
2. The automatic voice diaphragm dome assembling system of claim 1, wherein: the method for obtaining the voice diaphragm frame in the voice diaphragm image comprises the following steps:
step 1, carrying out gray image processing on a picture acquired by a voice film camera and a picture acquired by a dome camera;
step 2, extracting a rectangular region of interest from the picture acquired by the voice film camera and the picture acquired by the dome camera, thereby acquiring a rectangular region of interest (ROI);
step 3, after carrying out graying image processing on the picture acquired by the voice film camera and the picture acquired by the dome camera, carrying out binarization processing on the acquired graying images to prepare for extracting a rectangular frame;
step 4, a plurality of noise points exist in the binary image of the voice film camera and the binary image of the dome camera, a connected domain with a small black area is removed by using an OpenCV writing algorithm, the image is subjected to open operation, and the core of the open operation is defined to be in negative correlation with the threshold value of the binary image, so that burrs are removed;
step 5, Canny edge detection is carried out on the image after the opening operation, hough line transformation is carried out, and each line segment is drawn in the image in sequence;
and 6, solving a minimum envelope rectangle of the Hough line segment graph through a minAreaRect function provided by OpenCV, and drawing rectangular frames of parts to be assembled in the original images of the sound film camera and the dome camera.
3. The automatic voice film dome assembling system according to claim 1 or 2, wherein the method for obtaining the rotation angle of the manipulator around the z-axis comprises obtaining the center coordinates of the voice film frame, and the deviation angle θ 1 of the connecting line of the center coordinates as the origin point and the corner point of the voice film frame and the X-axis or the Y-axis, and recording the machine coordinates (X1, Y1) when the voice film is shot; obtaining the central coordinate of a ball top frame, and a ball top deflection angle theta 2 between a connecting line of the central coordinate as an original point and an original point-ball top frame corner point and an X axis or a Y axis, and recording machine tool coordinates (X2, Y2) when the ball top is shot; converting the pixel coordinates of the characteristic points of the dome frame into a machine tool coordinate system, converting the pixel coordinates of the characteristic points of the sound film frame into the machine tool coordinate system, enabling the center of the sound film frame to coincide with the center of the dome frame, and calculating the difference value of the deflection angle of the sound film and the deflection angle of the dome, wherein the difference value is the rotation angle of the mechanical hand around the Z axis.
4. The system for automatically assembling a voice diaphragm dome according to claim 1, wherein the method for calculating the relative position of the dome voice diaphragm comprises:
the machine coordinates (x ', y') of the diaphragm are:
x′＝xc1+x1
y′＝yc1+y1；
the machine coordinates (x ", y") of the dome are:
x″＝xc2+Δx+x0
y″＝yc2+Δy+y0；
the relative position of the dome voice diaphragm (dx, dy) is therefore:
dx＝x′-x″＝xc1+x1-(xc2+Δx+x0)；
dy＝y′-y″＝yc1+y1-(yc2+Δy+y0)；
in the above formula, (x0, y0) is the machine coordinates of the film camera and the dome camera during the opposite shooting; (x1, y1) sucking a dome by a vacuum chuck, controlling a three-axis motion system to move to a sound film photographing position, and recording machine tool coordinates when the sound film is photographed; (xc1, yc1) acquiring a voice diaphragm image through a film camera, and processing the image to obtain the center coordinates of a rectangular frame of the voice diaphragm; (xc2, yc2) is to obtain the dome image through the dome camera, and the center coordinates of the dome rectangle are obtained through processing the image.
5. The automatic voice film dome assembling system according to claim 1, wherein the machine tool comprises a base four-axis precision moving assembling platform, a mechanical arm, a voice film image acquisition assembly, a dome image acquisition assembly, a voice film tool module and a dome tool module; the four-axis precision moving assembly platform comprises a sound film image acquisition assembly, a ball top image acquisition assembly, a sound film tool module and a ball top tool module, wherein the sound film tool module and the ball top tool module are arranged on a base.
6. The automatic voice diaphragm dome assembling system of claim 5, wherein the four-axis precision moving assembling platform comprises an X-axis guide rail, a Y-axis guide rail and a Z-axis guide rail; the X-axis guide rail is fixed on the base, the Y-axis guide rail is movably arranged on the X-axis guide rail, and the Z-axis guide rail is movably arranged on the Y-axis guide rail; the Z-axis guide rail is provided with a slide block, and the slide block is provided with a manipulator and a voice film camera.
7. The voice film dome automatic assembly system of claim 6, wherein the voice film camera is configured with the voice film light source, and/or the dome camera is configured with the dome light source.
8. The automatic voice diaphragm dome assembling system of claim 6, wherein the robot comprises a base frame, a vacuum chuck and a rotating shaft, the vacuum chuck is disposed at one end of the rotating shaft and coaxial with the rotating shaft, the base frame is fixed relative to the voice diaphragm camera, the rotating shaft is disposed on the base frame, and the rotating shaft is connected to the rotary driving member.
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