CN103954216B - Strong specular reflection workpiece thin and narrow groove detection device and method based on spherical surface light sources - Google Patents

Abstract

The invention relates to a device and method for detecting thin and narrow grooves of strong specular reflection workpieces based on a spherical light source, belonging to the field of welding automation. The device and method use a spherical light source to irradiate the surface of the workpiece to obtain a surface image of the workpiece with uniform gray scale, and use a laser array to determine the relative pose between the welding torch and the workpiece, so as to realize the automatic detection of the thin and narrow groove of the workpiece with strong specular reflection. The invention uses a spherical light source to irradiate the workpiece surface with strong specular reflection to obtain a uniformly illuminated workpiece surface image. The groove features in the image are obvious, which is convenient for accurately extracting the center position of the groove, and the detection accuracy can reach 0.03mm; the relative position of the workpiece and the welding gun The attitude relationship can be obtained quickly and accurately through the laser array; the system structure is simple, the detection accuracy is high, the real-time performance is good, and the cost is low. It can be applied to the automatic detection of the groove of the workpiece on the strong specular reflection surface, especially for the groove gap less than 0.1 mm narrow groove workpiece high energy beam welding automatic tracking occasions.

Description

Thin and narrow groove detection device and method of strong specular reflection workpiece based on spherical light source

technical field

The invention belongs to the field of welding automation, and in particular relates to the design of a device and method for detecting thin and narrow grooves of workpieces with strong specular reflection based on spherical light sources.

Background technique

The lightweight development of aerospace components and the improvement of reliability requirements pose a major challenge to weld visual inspection and tracking. First, the groove form of the workpiece to be welded is generally I-type butt groove, the groove gap is extremely small (generally no more than 0.1mm), and a slight deviation in the relative posture of the welding torch and the groove may cause serious welding defects , has extremely high requirements for detection and tracking accuracy; second, most aerospace components are made of aluminum-magnesium alloy, with a reflectivity of more than 95%, and the strong specular reflection on the surface makes the image brightness extremely uneven, and may even cover the groove main feature information. The traditional seam tracking method identifies the area to be welded by detecting the distortion characteristics of the structured light strip. This method is too dependent on the macroscopic geometric structure characteristics of the groove, and cannot be applied to the detection of thin and narrow grooves where the distortion of the structured light strip is not obvious.

The Chinese patent document (notification number is CN101927395B) discloses a welding seam tracking detection device and method, which projects a laser spot with specific contour features on the surface of the workpiece, uses a CCD camera to collect the surface image of the workpiece, and detects the groove in the spot The shadow detects the lateral offset of the groove, and calculates the relative pose between the workpiece surface and the welding torch by detecting the shape, position and size of the spot. The gray scale of the image collected by this method is very uneven, which makes it difficult to accurately extract the edge of the spot. This is because the metal surface produces strong specular reflection of the laser, resulting in local saturation of the image; Speckle is formed on the surface, which exacerbates grayscale non-uniformity. Reducing the exposure time, reducing the aperture, and using polarizers to extinction can reduce the influence of specular reflection light to a certain extent, but the laser speckle phenomenon becomes more and more obvious, which cannot improve the uniformity of image grayscale.

In summary, there is no device and method that has high detection accuracy, strong real-time performance, good image gray uniformity, and is suitable for the detection of thin and narrow grooves on workpieces with strong specular reflection surfaces.

Contents of the invention

The purpose of the present invention is to address the deficiencies of the prior art, and propose a device and method for detecting thin and narrow grooves of workpieces with strong specular reflection based on spherical light sources. In order to realize the automatic recognition of the groove, especially for the automatic detection of narrow grooves with a groove gap of less than 0.1mm, problems such as uneven gray scale of the image caused by strong specular reflection on the surface, and difficulty in accurately determining the relative pose of the welding torch and the workpiece are solved.

Technical scheme of the present invention is as follows:

The thin and narrow groove detection device for strong specular reflection workpiece based on spherical light source is characterized in that it includes a control unit, a sensor housing, and a spherical light source, laser array, imaging element and filter element installed in the sensor housing; the control unit The spherical light source, the laser array and the imaging element are respectively connected by wires; the sensor housing is consolidated with the welding torch; the spherical light source includes a light-emitting diode array, a spherical diffuse reflection shell and a light-transmitting hole; the light-emitting diode array is distributed At the bottom of the spherical diffuse reflection shell, the light emitted by it is projected on the surface of the workpiece after being reflected by the spherical diffuse reflection shell; or the light emitting diode array is distributed on the surface of the spherical diffuse reflection shell, which emits A part of the light is directly projected on the surface of the workpiece, and the other part is projected on the surface of the workpiece after being reflected by the spherical diffuse reflection shell; the laser array includes at least three lasers; the laser spot emitted by the laser array is projected on the surface of the workpiece Above; the reflected light on the surface of the workpiece is taken into the imaging element for imaging after passing through the light transmission hole and the filter element;

The thin and narrow groove detection device of strong specular reflection workpiece based on spherical light source is characterized in that: the imaging element is a charge-coupled device, a complementary metal oxide semiconductor imaging device, a position sensitive device or a charge injection device; the luminous wavelength of the spherical light source and The emission wavelength of the laser array is consistent with the central wavelength of the filter element; the central wavelength of the filter element is within the sensitive wavelength range of the imaging element;

A method for detecting thin and narrow grooves of strong specular reflection workpieces based on a spherical light source, characterized in that the method includes the following steps:

1) Establish the imaging element coordinate system {C}, the origin of the imaging element coordinate system {C} is the optical center of the imaging element, and the vertical axis direction is the same as the optical axis direction of the imaging element; establish on the image collected by the imaging element Pixel coordinate system {P}; assuming that the laser array includes N lasers, N is a positive integer greater than or equal to 3;

2) Calibrate the imaging element to obtain the conversion relationship between any point (u, v) ^T in the pixel coordinate system {P} and the point (x, y, z) ^T in the imaging element coordinate system {C}:

And in the imaging component coordinate system {C}, the laser propagation path equation emitted by the i-th laser:

X _i ＝X _i,0 +t _i S _i

Among them, f ₁ and f ₂ are the conversion functions between the pixel coordinate system {P} and the imaging element coordinate system {C}; _i is a positive integer greater than or equal to 1 and less than or equal to N; Xi and Xi _{, 0} is a point on the laser propagation path emitted by the i-th laser; S _i is the unit direction vector of the laser propagation path emitted by the i-th laser; t _i is the directed distance between points X _i and X _i,0 ;

3) The control unit sends a trigger signal to alternately light up the laser array and the spherical light source, and make the imaging element synchronously capture images when different light sources are on; when the laser array is on, the The control unit processes the image collected by the imaging element to obtain the coordinates (u _i , v _i ) ^T of the i-th laser spot in the pixel coordinate system {P}; according to the i-th laser spot in the pixel coordinate system { Coordinates (u _i , v _i ) ^T in P}, calculate the coordinates A _i of the i-th laser spot in the imaging component coordinate system {C}:

A _i ＝[X _i,0 +t _i,1 (u _i ,v _i )·S _i +t _i,2 (u _i ,v _i )·V _i (u _i ,v _i )]/2

in,

Assuming that the surface of the workpiece projected by the laser spot is approximately a plane, record this plane as W; let the equation of the plane W be X ^T α=1,

Where α is the normal vector of the plane W, X is any point on the plane W; according to the points A _i are all on the plane W, there are:

which is:

Use the linear least square method to obtain the normal vector α of the plane W;

When the spherical light source is on, the control unit processes the image collected by the imaging element to obtain the coordinates (u _w , v _w ) ^T of the groove center point in the pixel coordinate system {P}; according to the groove center The point is located on the plane W, and the coordinate B of the groove center point in the imaging component coordinate system {C} is obtained:

B＝V _w (u _w ,v _w )/[α ^T V _w (u _w ,v _w )]

in,

V _w (u _w ,v _w )=[f ₁ (u _w ,v _w ),f ₂ (u _w ,v _w ),1] ^T .

The invention uses a spherical light source to irradiate the surface of the workpiece to obtain the groove position offset, and uses a laser array to determine the pose information of the workpiece surface, so as to realize the detection of the thin and narrow groove of the workpiece with strong specular reflection. Adopting the device and method of the present invention can meet several target requirements in groove detection: the gray scale of the image is uniform, the groove features are obvious, and it is convenient to detect the groove position in real time and accurately; it can quickly and accurately determine the position of the welding gun relative to the workpiece surface. Pose information, including the lateral offset, height offset, lateral deflection, longitudinal deflection, etc. of the welding torch; the detection accuracy is high, and the detection accuracy can reach 0.03mm; the system structure is simple, low cost, high real-time performance, suitable for strong Automatic groove detection of specular reflection workpieces (such as aluminum alloy workpieces, etc.), especially suitable for narrow groove detection occasions with groove gaps less than 0.1mm.

Description of drawings

Fig. 1 is a structural schematic diagram of a first embodiment of a device for detecting thin and narrow grooves of a strong specular reflection workpiece based on a spherical light source.

Fig. 2 is a schematic structural diagram of a second embodiment of a device for detecting thin and narrow grooves of workpieces with strong specular reflection based on a spherical light source.

Fig. 3 is the groove images collected by the imaging element when the spherical light source is turned on in the first embodiment and the second embodiment of the present invention.

Fig. 4 is a schematic diagram of using a laser array to determine the pose of a workpiece in the first embodiment and the second embodiment of the present invention.

Fig. 5 is a flowchart of groove detection in the first embodiment and the second embodiment of the present invention.

In Figures 1 to 5:

1—Control unit; 2—Sensor shell; 3—Spherical light source; 31—LED array; 32—Spherical diffuse reflection shell; 33—Light hole; 4—Laser array; 41—First laser; 42—Second Laser; 43—third laser; 5—imaging element; 6—filter element; 7—workpiece; 71—base material; 72—groove; 8—welding torch.

detailed description

The structure, principle and working process of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the schematic diagram of the structure principle of the first embodiment of the strong specular reflection workpiece thin and narrow groove detection device and method based on the spherical light source proposed by the present invention, including a control unit 1, a sensor housing 2, a spherical light source 3, a laser array 4, Imaging element 5 and filter element 6 . The control unit 1 is connected to the spherical light source 3, the laser array 4 and the imaging element 5 through wires; the control unit 1 sends a trigger signal to make the spherical light source 3 and the laser array 4 flash alternately, and the imaging element 5 is synchronized Collect surface images of the workpiece 7 illuminated by different light sources; the sensor housing 2 is consolidated with the welding torch 8; the spherical light source 3 includes a light-emitting diode array 31, a spherical diffuse reflection housing 32 and a light-transmitting hole 33; the light-emitting diode array 31 is distributed on the bottom of the spherical diffuse reflection housing 32, and the light emitted by it is projected on the surface of the workpiece 7 after being reflected by the spherical diffuse reflection housing 32; the laser array 4 includes at least three lasers; the laser array The emitted laser spot is projected on the surface of the workpiece 7; the reflected light on the surface of the workpiece 7 passes through the light transmission hole 33 and the filter element 6, and then enters the imaging element 5 for imaging. The quantity of laser device is three in the present embodiment, is respectively the first laser device 41, the second laser device 42 and the 3rd laser device 43, and wavelength is 635nm; Described imaging element 5 is the CCD camera of 1024 * 1024, and field of view is 30mm ×30mm, the detection accuracy is 0.03mm; the wavelength range of the emitted light of the light-emitting diode array 31 is 635-645nm; the filter element 6 is a narrow-band filter with a center wavelength of 635nm and a full width at half maximum of 10nm; The light intensity at 635-645nm is relatively weak, so the selected filter element 6 can effectively filter out arc light interference.

The spatial distribution of the light intensity emitted by the LED array 31 has relatively large inhomogeneity, which is caused by the sparse arrangement of the LEDs on the one hand and the directional inhomogeneity of the light intensity of each LED on the other hand. The inner surface of the spherical diffuse reflection housing 32 is equivalent to the Ulbricht sphere, and the light intensity integration effect of the Ulbricht sphere can eliminate the inhomogeneity of the light intensity emitted by the LED array 31 to a certain extent, so that the projection on the workpiece 7 The light intensity on the surface is uniform; the outgoing light of the light emitting diode array 31 is incoherent light, there is no speckle problem existing in the laser light source, and the light intensity uniformity is good.

Fig. 2 is a schematic diagram of the structure principle of the second embodiment of the device and method for detecting thin and narrow grooves of workpieces with strong specular reflection based on the spherical light source proposed by the present invention. Different from the first embodiment, in this embodiment, the LED array 31 is distributed on the inner surface of the spherical diffuse reflection housing 32 . Due to the light intensity integration effect of the spherical diffuse reflection shell 32, the light intensity projected on the surface of the workpiece 7 is very uniform.

Fig. 3 is the original image of the bevel captured by the imaging element 5 when the spherical light source 3 is turned on in the first embodiment and the second embodiment of the present invention. The base metal 71 and the groove 72 have great differences in optical reflection characteristics: the surface of the base metal 71 has a gray scale close to saturation due to the strong specular reflection; the light projected on the groove 72 is reflected by the side wall of the groove 72, without The imaging element 5 can be taken in, and it appears in the image as a curve whose gray level is close to zero. The strong difference in gray scale between the base material 71 and the bevel 72 provides a guarantee for the rapid and accurate extraction of the bevel 72 position.

Fig. 4 is a schematic diagram of using a laser array to determine the pose of a workpiece in the first embodiment and the second embodiment of the present invention. Since the light spot projected by the spherical light source 3 on the surface of the workpiece has no obvious edge contour features, it is difficult to determine the pose of the welding torch 8 relative to the workpiece 7 . The present invention uses the laser array 4 to determine the pose of the welding torch 8 relative to the workpiece 7 . Assume that the laser array 4 is composed of N lasers, where N is a positive integer. Establish pixel coordinate system {P} on the image collected by imaging element 5, any point on the pixel coordinate system {P} represents the pixel coordinate value of imaging element 5 image; establish imaging element coordinate system {C}, imaging element coordinate system { The origin of C} is the optical center of the imaging element 5 , and the direction of the vertical axis is the same as that of the optical axis of the imaging element 5 .

Fig. 5 is a flowchart of groove detection in the first embodiment and the second embodiment of the present invention. When the laser array 4 is on and the spherical light source 3 is off, the pose of the welding torch 8 relative to the surface of the workpiece 7 can be obtained by calculation; The pixel coordinates in the image, as well as the aforementioned pose relationship of the welding torch 8 relative to the surface of the workpiece 7, can be calculated to obtain the three-dimensional space coordinates of the center point of the groove. The control unit 1 is responsible for triggering the spherical light source 3, the laser array 4 and the imaging element 5, processing the image collected by the imaging element 5, and automatically adjusting the relative pose of the welding torch 8 and the workpiece 7 according to the calculation results to realize automatic tracking.

When the laser array 4 is on and the spherical light source 3 is off, the equation of the propagation path of the laser light emitted by the i-th laser in the imaging element coordinate system {C} is:

X _i ＝X _i,0 +t _i S _i (1)

Among them, X _i and X _i,0 are points on the laser propagation path emitted by the i-th laser, S _i is the unit direction vector of the laser propagation path emitted by the i-th laser, and t _i is the point X _i and point X _{i , the directed distance of 0} .

After calibration by Zhang Zhengyou et al., X _{i, 0} and S _i in formula (1), as well as any point (u, v) ^T on the pixel coordinate system {P} and corresponding to the imaging element coordinate system {C} can be obtained The relationship between the points (x,y,z) ^T on the , that is:

Among them, the functions f ₁ and f ₂ can be obtained through calibration.

Assume that the pixel coordinates of the light spot projected by the i-th laser on the workpiece 7 in the image of the imaging element 5 are (u _i , v _i ) ^T , which corresponds to a point on the coordinate system {C} of the imaging element as A _i =(x _i ,y _i ,z _i ) ^T , 1≤i≤N, and i is a positive integer, according to formula (2):

A _i ＝t _i,2 (u _i ,v _i )V _i (u _i ,v _i ) (3)

Among them, V _i (u _i ,v _i )=[f ₁ (u _i ,v _i ),f ₂ (u _i ,v _i ),1] ^T , t _i,2 (u _i ,v _i ) is determined by The undetermined parameters of u _i and vi _i . Formula (3) shows that point A _i is located on the straight line represented by formula (3), the straight line passes through the origin of the imaging element coordinate system {C}, and the direction vector is V _i (u _i , v _i ).

Since the point A _i is on the straight line represented by formula (1), therefore:

A _i ＝X _i,0 +t _i,1 (u _i ,v _i )S _i (4)

Among them, t _i,1 (u _i , v _i ) is an undetermined parameter depending on u _i and v _i .

Point A _i is the intersection point of two straight lines represented by formula (3) and formula (4), and vector S _i and V _i (u _i , v _i ) are not parallel, otherwise point A _i will not exist. However, due to measurement errors, interference noise, etc., the straight lines represented by formulas (3) and (4) are generally straight lines with different planes. At this time, the point A _i is taken as the midpoint of the common vertical line of the two straight lines. Since the length of the common vertical line segment of two straight lines with different planes is the shortest one among the line segments connecting two points on the two straight lines with different planes, the objective function is established:

, and find the minimum value of the objective function g, then t _i,1 (u _i ,v _i ) and t _i,2 (u _i ,v _i ) can be determined, so as to determine the coordinate value of point A _i .

make

which is:

The coefficient determinant of equation (7):

Wherein, <S _i ,V _i (u _i ,v _i )> represents the angle between vector S _i and V _i (u _i ,v _i ). Since the vectors S _i and V _i (u _i , v _i ) are not parallel, the determinant of formula (8) is greater than zero, and there is a unique solution to equation system (7), and its solution is:

Since the point A _i is the midpoint of the common vertical line of the straight line represented by formula (3) and formula (4), therefore:

A _i ＝[X _i,0 +t _i,1 (u _i ,v _i )·S _i +t _i,2 (u _i ,v _i )·V _i (u _i ,v _i )]/2 (11 )

It can be proved that when the straight lines represented by formula (3) and formula (4) are not straight lines with different planes, the coordinates of their intersection points still satisfy formula (11).

So far, the coordinates of the light spot projected by the i-th laser on the surface of the workpiece 7 relative to the coordinate system {C} of the imaging element are given by formula (11). During actual detection, ensure that all laser spots are projected near the groove 72, and assume that the surface of the workpiece projected by the laser spots is approximately a plane, set the plane as W, and its equation is X ^T α=1, where α is the method of the plane W vector. Since the points A _i are all on the plane W, therefore:

which is:

Only when N≥3, the formula (13) has a unique least squares solution, and the equation of the plane W can be determined. Therefore, the laser array 4 is required to include at least three lasers in the present invention.

When the spherical light source 3 is turned on and the laser array 4 is turned off, the imaging element 5 collects a grayscale image of the workpiece surface. A binary image I is obtained after performing threshold segmentation on the image collected by the imaging element 5 . In the image I, the gray value at the base material 71 is one, and the gray value at the groove 72 is zero. For the j-th line of the image of the imaging element 5, the coordinates of the groove center point in the pixel coordinate system {P} are:

u _w = j (14)

Among them, I(j,v) represents the gray value of the pixel in the jth row and vth column of the image I, and #{v:I(j,v)=0} represents the pixel that satisfies I(j,v)=0 The total number of points, sum{v:I(j,v)=0} means the sum of the column numbers of pixel points satisfying I(j,v)=0.

The local area of the workpiece surface can be approximated as a plane W, and the point B in the imaging element coordinate system {C} corresponding to the point (u _w , v _w ) is on the plane W. According to formula (2) and the equation X ^T α=1 of the plane W, it can be known that point B satisfies:

B＝t _w (u _w ,v _w )V _w (u _w ,v _w ) (16)

B ^T α＝1 (17)

where t _w (u _w ,v _w ) is an undetermined parameter depending on u _w and v _w , and:

V _w (u _w ,v _w )=[f ₁ (u _w ,v _w ),f ₂ (u _w ,v _w ),1] ^T (18)

The coordinates of the groove center point B in the imaging element coordinate system {C} can be calculated from formula (16) and formula (17):

B＝V _w (u _w ,v _w )/[α ^T V _w (u _w ,v _w )] (19)

According to the coordinates of the center point of the groove and the normal vector of the workpiece surface, the relative pose of the welding torch and the workpiece is automatically adjusted to realize automatic identification and tracking of narrow grooves.

It should be noted that the above embodiments are only used to illustrate the present invention rather than limit the solution described in the present invention; therefore, although the specification has described the present invention in detail with reference to the above embodiments, those of ordinary skill in the art should understand , the present invention can still be modified or equivalently replaced. For example, the number of lasers included in the laser array 4 can be greater than 3 to improve the detection accuracy of the relative pose of the welding torch and the workpiece surface, and a higher-resolution imaging element can be used to improve the groove. Detection precision, filter element 6 can adopt spectroscopic element such as monochromator etc.; And all technical schemes and improvements thereof that do not deviate from the spirit and scope of the present invention, it all should be covered in the middle of the claim scope of the present invention.

The invention adopts a spherical light source, a laser array, an imaging element, etc. to detect the thin and narrow grooves of strong specular reflection workpieces; the detection method does not depend on the macroscopic geometric structure characteristics of the grooves, and the detection accuracy can be as high as 0.03mm; the spherical light source is used to irradiate the surface of the workpiece , so that the surface brightness of the workpiece is uniform, the gray level of the base metal is close to saturation, and the gray level of the bevel area is close to zero. On the one hand, it can ensure the accurate extraction of the bevel position in the image, and on the other hand, it reduces the difficulty of image processing and the complexity of the algorithm. Complexity; the laser array is used to determine the pose information of the workpiece surface, the detection method is simple, and the pose offset of the welding torch relative to the workpiece surface can be calculated quickly and accurately; the filter element is used to eliminate the interference of ambient light and arc light on the imaging element , improve the adaptability of the system to the actual welding operation environment; the system has simple structure, high detection accuracy, good real-time performance, and low cost. It is suitable for the detection of strong specular reflection workpiece grooves, especially for thin and narrow grooves with a groove gap less than 0.1mm High-energy beam welding (laser welding, electron beam welding, plasma arc welding, etc.) of grooved workpieces for automatic tracking occasions.

Claims (3)

1. The thin and narrow groove detection device of strong specular reflection workpiece based on a spherical light source is characterized in that: it comprises a control unit (1), a sensor housing (2), and a spherical light source (3) installed in the sensor housing, a laser array ( 4), imaging element (5) and optical filter element (6); Described control unit (1) is connected with described spherical light source (3), laser array (4) and imaging element (5) by wire respectively; The sensor housing (2) is consolidated with the welding torch (8); the spherical light source (3) includes a light-emitting diode array (31), a spherical diffuse reflection housing (32) and a light-transmitting hole (33); the light-emitting diode array ( 31) Distributed at the bottom of the spherical diffuse reflection shell (32), the light emitted by it is projected on the surface of the workpiece (7) after being reflected by the spherical diffuse reflection shell (32); or the light emitting diode array (31 ) is distributed on the surface of the spherical diffuse reflection shell (32), a part of the light emitted by it is directly projected on the surface of the workpiece (7), and the other part is projected on the workpiece (7) after being reflected by the spherical diffuse reflection shell (32). 7) on the surface; the laser array (4) includes at least three lasers; the laser spot emitted by the laser array (4) is projected on the surface of the workpiece (7); the reflected light on the surface of the workpiece (7) passes through the After the light hole (33) and the filter element (6), the imaging element (5) is captured for imaging. 2. The thin and narrow groove detection device based on a spherical light source as claimed in claim 1, wherein the imaging element is a charge-coupled device, a complementary metal oxide semiconductor imaging device, a position sensitive device or a charge-coupled device. The injection device; the luminous wavelength of the spherical light source and the luminous wavelength of the laser array are consistent with the central wavelength of the optical filter element; the central wavelength of the optical filter element is within the sensitive wavelength range of the imaging element. 3. adopt the thin and narrow bevel detection method of strong specular reflection workpiece based on the spherical light source of device as claimed in claim 1, it is characterized in that the method comprises the following steps: 1) Establish the imaging element coordinate system {C}, the origin of the imaging element coordinate system {C} is the optical center of the imaging element, and the vertical axis direction is the same as the optical axis direction of the imaging element; establish on the image collected by the imaging element Pixel coordinate system {P}; assuming that the laser array includes N lasers, N is a positive integer greater than or equal to 3; 2) Calibrate the imaging element to obtain the conversion relationship between any point (u, v) ^T in the pixel coordinate system {P} and the point (x, y, z) ^T in the imaging element coordinate system {C}: $\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; z</span>}\\ \mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; u</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; z</span>}\end{array}\right.$ And in the imaging component coordinate system {C}, the laser propagation path equation emitted by the i-th laser: X _i ＝X _i,0 +t _i S _i Among them, f ₁ and f ₂ are the conversion functions between the pixel coordinate system {P} and the imaging element coordinate system {C}; _i is a positive integer greater than or equal to 1 and less than or equal to N; Xi and Xi _{, 0} is a point on the laser propagation path emitted by the i-th laser; S _i is the unit direction vector of the laser propagation path emitted by the i-th laser; t _i is the directed distance between points X _i and X _i,0 ; 3) The control unit sends a trigger signal to alternately light up the laser array and the spherical light source, and make the imaging element synchronously capture images when different light sources are on; when the laser array is on, the The control unit processes the image collected by the imaging element to obtain the coordinates (u _i , v _i ) ^T of the i-th laser spot in the pixel coordinate system {P}; according to the i-th laser spot in the pixel coordinate system { Coordinates (u _i , v _i ) ^T in P}, calculate the coordinates A _i of the i-th laser spot in the imaging component coordinate system {C}: A _i ＝[X _i,0 +t _i,1 (u _i ,v _i )·S _i +t _i,2 (u _i ,v _i )·V _i (u _i ,v _i )]/2 in, V _i (u _i ,v _i )＝[f ₁ (u _i ,v _i ),f ₂ (u _i ,v _i ),1] ^T ${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}{{<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}$ ${\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}{{<span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; \&lsqb;</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span>}$ Assuming that the surface of the workpiece projected by the laser spot is approximately a plane, record this plane as W; set the equation of the plane W as X ^T α=1, where α is the normal vector of the plane W, and X is any point on the plane W; according to point A _i are all on the plane W, there are: ${\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}$ which is: $\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\\ {\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ {\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; N</span>}}^{\mathrm{<span\; class="notranslate">\; T</span>}}\end{array}\right]\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; =</span>\left[\begin{array}{c}\mathrm{<span\; class="notranslate">\; 1</span>}\\ \mathrm{<span\; class="notranslate">\; 1</span>}\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ \mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right]$ Use the linear least squares method to obtain the normal vector α of the plane W; When the spherical light source is on, the control unit processes the image collected by the imaging element to obtain the coordinates (u _w , v _w ) ^T of the groove center point in the pixel coordinate system {P}; according to the groove center The point is located on the plane W, and the coordinate B of the groove center point in the imaging component coordinate system {C} is obtained: B＝V _w (u _w ,v _w )/[α ^T V _w (u _w ,v _w )] in, V _w (u _w ,v _w )=[f ₁ (u _w ,v _w ),f ₂ (u _w ,v _w ),1] ^T .