Calibration method for position relationship between hetero-directional dual cameras

Abstract

The application discloses a kind of position relation calibration methods between hetero-directional dual cameras, comprising the following steps: the first step, the physical center coordinates of calibration board cover are obtained by taking photographing calibration board cover of lower camera;The second step, calibration board cover is sucked by suction nozzle;The third step, after suction nozzle sucks calibration board cover, it is moved to the place of upper camera and is photographed, and the physical center coordinates of calibration board cover are obtained;The fourth step, the position relation between lower camera and upper camera is deduced by the position relation of calibration board cover between lower camera and upper camera.The position relation calibration method between hetero-directional dual cameras can more accurately calculate the position relation between positioning camera and upper camera.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of patch machine mounting, and particularly to a position relationship calibration method between two cameras in different directions. BACKGROUND

[0002] At present, an intelligent mounting device of a FI100 model on the market needs to complete the following calculation steps when calibrating the relative position relationship between a downward-looking camera and an upward-looking camera:

[0003] Calculation step one: the nozzle center is moved to the center of the upward-looking camera to clearly image, and the physical center coordinates of the upward-looking camera are calculated through the relationship between the nozzle center and the image center;

[0004] Calculation step two: the position relationship between the downward-looking camera and the nozzle is calibrated, and the position relationship between the downward-looking camera and the upward-looking camera is calculated;

[0005] However, due to the influence of the nozzle shape and the perpendicularity of the nozzle shaft, there is some deviation in the calculated physical center of the nozzle, which leads to deviation in the calculation of calculation step one, and further affects the calibration of the position relationship between the downward-looking camera and the upward-looking camera, and finally affects the mounting precision. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art.

[0007] To this end, the present application provides a position relationship calibration method between two cameras in different directions, which can more accurately calculate the position relationship between the downward-looking camera and the upward-looking camera.

[0008] According to the position relationship calibration method between two cameras in different directions of the present application, a downward-looking camera, an upward-looking camera, a calibration board cover and a nozzle are used, the downward-looking camera moves together with the nozzle, and the physical center of the downward-looking camera and the physical center of the nozzle have a fixed distance L;

[0009] The present application has the beneficial effect that the physical center coordinates of the calibration board cover are obtained by the downward-looking camera taking a photo of the calibration board cover, the nozzle is moved to the upward-looking camera after sucking the calibration board cover to take a photo, the physical center coordinates of the calibration board cover are obtained, and the position relationship between the downward-looking camera and the upward-looking camera is calculated according to the physical center coordinates of the calibration board cover under the downward-looking camera, the physical center coordinates of the calibration board cover under the upward-looking camera and the distance of the nozzle sucking the calibration board cover moving to the upward-looking camera. This method is particularly suitable for the double-camera relationship calibration before the mounting of the surface mounting patch machine based on machine vision, and can more accurately calculate the position relationship between the downward-looking camera and the upward-looking camera in the mounting process of the patch machine, and can completely eliminate the calibration influence caused by the difference in the nozzle shape and the nozzle shaft perpendicularity.

[0010] According to one embodiment of the present application, in the first step, the angle of the cover of the calibration board under the downward-looking camera is also calculated; in the third step, the angle of the cover of the calibration board under the upward-looking camera is also calculated.

[0011] According to one embodiment of the present application, the method further employs a base and a first vacuum suction pump, the upper surface of the base is provided with a recess, and a plurality of suction holes connected with the first vacuum suction pump are arranged at the position corresponding to the recess along the height direction of the base.

[0012] According to one embodiment of the present application, the cover of the calibration board is made of glass, and the position relationship calibration method further employs a calibration board substrate made of ceramic.

[0013] According to one embodiment of the present application, in the first step, the specific steps are as follows: the calibration board substrate is placed in the recess, the cover of the calibration board is placed on the upper surface of the calibration board substrate, after the first vacuum suction pump under the recess is turned on, the plurality of suction holes in the recess tightly suck the cover of the calibration board through the through holes in the calibration board substrate by the suction force generated by the first vacuum suction pump, the downward-looking camera is moved to the clear imaging position above the cover of the calibration board to take a photo, and the current physical center coordinates (x1, y1) of the downward-looking camera are recorded, the physical center coordinates (X dc , Y dc ) and the angle A dc of the cover of the calibration board under the field of view of the downward-looking camera are calculated.

[0014] According to one embodiment of the present application, in the second step, the specific steps are as follows: the suction nozzle is moved to the position 2-3 mm above the cover of the calibration board, and is slowly lowered until the suction nozzle is pressed against the surface of the cover of the calibration board, then the first vacuum suction pump under the recess is turned off, at this time, the vacuum suction force of the recess under the calibration board disappears, and the second vacuum suction pump matched with the suction nozzle is turned on, the suction nozzle sucks the cover of the calibration board under the action of the second vacuum suction pump, and the current physical center coordinates (x2, y2) of the downward-looking camera are recorded.

[0015] According to one embodiment of the present application, in the third step, the specific steps are as follows: after the suction nozzle sucks the cover of the calibration board, the suction nozzle with the cover of the calibration board is moved to the upward-looking camera until the cover of the calibration board is clearly imaged, the upward-looking camera takes an upward photo of the cover of the calibration board, the physical center coordinates (X dc ’ , Y dc ’ ) and the angle A dc ’ of the cover of the calibration board under the field of view of the upward-looking camera are calculated, and the current physical center coordinates (x3, y3) of the upward-looking camera are calculated.

[0016] According to one embodiment of the present application, the calculation step of the current physical center coordinate (x3, y3) of the upper-view camera is: knowing the physical center coordinate (X dc , Y dc ) of the calibration board cover under the lower-view camera, moving the calibration board cover to above the upper-view camera by the suction nozzle, setting the axis coordinate of the start position of the calibration board cover by the suction nozzle as m, setting the axis coordinate of the end position of the calibration board cover after moving to above the upper-view camera by the suction nozzle as n, then calculating the distance of the calibration board cover moved to the upper-view camera by the suction nozzle as n-m, and further calculating the physical center coordinate of the calibration board cover above the upper-view camera, i.e., the physical center coordinate (x3, y3) of the calibration board cover above the upper-view camera is equal to the sum of the physical center coordinate (X dc , Y dc ) of the calibration board cover under the lower-view camera, the distance of the suction nozzle moved to the calibration board cover, and the distance n-m of the calibration board cover moved to the upper-view camera by the suction nozzle.

[0017] Other features and advantages of the present application will be set forth in the descriptions below, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description and the drawings.

[0018] In order to make the above objects, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are specifically described in detail below, and the accompanying drawings are referred to. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort.

[0020] Figure 1 is a position relationship diagram of the lower-view camera, the suction nozzle, the upper-view camera and the calibration device.

[0021] Figure 2 is a structure diagram of the calibration device in Figure 1 ;

[0022] Figure 3 is a schematic diagram of the calibration device without placing the calibration board substrate and the calibration board cover;

[0023] Figure 4 is a schematic diagram of the calibration device with the calibration board substrate;

[0024] Figure 5is a schematic diagram of a calibration device with a calibration board cover placed;

[0025] Figure 6 is the imaging effect of the calibration board cover under the downward-looking camera and the upward-looking camera.

[0026] The reference signs in the figure are: 1, downward-looking camera; 2, suction nozzle; 3, upward-looking camera; 4, calibration device; 5, base; 6, groove; 7, suction hole; 8, calibration board cover; 9, calibration board base plate. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0028] In the description of the present application, it should be understood that the terms “one side”, “the other side”, “both sides”, “between”, “middle”, “upper end”, “lower end” and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0029] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms “set”, “connected” should be understood broadly, for example, it can be fixedly connected, or detachably connected, or integrally connected, it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0030] In the process of the patch placement machine, in order to more accurately calculate the positional relationship between the downward-looking camera and the upward-looking camera, eliminate the calibration influence caused by the shape of the suction nozzle and the verticality difference of the suction nozzle axis, the positional relationship calibration method between the opposite cameras in the embodiments of the present application will be described in detail below with reference to the drawings.

[0031] See Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6The position relationship calibration method between the two opposite direction cameras of the application adopts a downward-looking camera 1, an upward-looking camera 3, a calibration board cover 8 and a suction nozzle 2, the downward-looking camera 1 moves together with the suction nozzle 2, and the physical center of the downward-looking camera 1 and the physical center of the suction nozzle 2 have a fixed distance L. Figure 1 .

[0032] It should be noted that the opposite direction means opposite directions, and the two cameras refer to a downward-looking camera 1 and an upward-looking camera 3. The downward-looking camera 1 is on the side of the suction nozzle 2, the downward-looking camera 1 moves together with the suction nozzle 2, the downward-looking camera 1 shoots downward, and the downward-looking camera 1 can also be called a positioning camera. The upward-looking camera 3 is fixed in position and shoots upward. Preferably, the downward-looking camera 1 adopts a CCD camera, and the upward-looking camera 3 adopts a CCD camera. The CCD camera is a camera that uses a CCD (Charge-Coupled Device) to convert an optical image into a digital signal for transmission.

[0033] The position relationship calibration method between the two opposite direction cameras of the application also adopts a base 5 and a first vacuum suction pump. The upper surface of the base 5 is provided with a groove 6, and a plurality of suction holes 7 connected with the first vacuum suction pump are arranged at the position corresponding to the groove 6 along the height direction of the base 5. The position relationship calibration method also adopts a calibration board substrate 9 made of ceramic material. The base 5, the groove 6, the suction hole 7, the calibration board cover 8 and the calibration board substrate 9 constitute a calibration device 4. Specifically, two grooves 6 are machined on the base 5, one of which is a first groove 6 without vacuum suction at the bottom and used for placing the calibration board cover 8, and the other is a second groove 6 with vacuum suction at the bottom and used for placing the calibration board substrate 9. The vacuum suction at the bottom of the second groove 6 can suck the calibration board cover 8 through the calibration board substrate 9. The calibration board cover 8 can also be called a calibration board Lid, where Lid is the English name of cover. The calibration board cover 8 and the calibration board substrate 9 are combined into a calibration board, which has two main functions: first, to obtain the distortion coefficient; second, to obtain the corresponding relationship between the spatial coordinate system and the image coordinate system.

[0034] The position relationship calibration method between the two opposite direction cameras of the application includes the following steps:

[0035] In the first step, the down-view camera 1 photographs the calibration plate cover 8 to obtain the physical center coordinates of the calibration plate cover 8: the down-view camera 1 is moved above the calibration plate cover 8, the down-view camera 1 photographs and records the current physical center coordinates of the down-view camera 1, and the physical center coordinates of the calibration plate cover 8 under the down-view camera 1 are calculated; wherein the current physical center coordinates of the down-view camera 1 are the coordinate values of the instructions issued by the motion controller, that is, the current physical center coordinates of the down-view camera 1 are directly read out through the motion controller on the device, and the coordinates issued by the motion controller essentially represent the axis coordinates, because the axis of the down-view camera 1 and the suction nozzle 2 only has a fixed distance and the relative position is unchanged, so the coordinates issued by the motion controller are also defaulted as the physical center coordinates of the down-view camera 1.

[0036] Further, in the first step, the angle of the calibration plate cover 8 under the down-view camera 1 is also calculated.

[0037] Preferably, in the first step, the specific steps are as follows: the calibration plate substrate 9 is placed in the groove 6, the calibration plate cover 8 is placed on the upper surface of the calibration plate substrate 9, after the first vacuum suction pump below the groove 6 is turned on, the suction holes 7 in the groove 6 tightly suck the calibration plate cover 8 through the through holes on the calibration plate substrate 9 by the suction force generated by the first vacuum suction pump, the down-view camera 1 is moved above the calibration plate cover 8 to clearly image and photograph it, and the current physical center coordinates (x1, y1) of the down-view camera 1 are recorded, and the physical center coordinates (X dc , Y dc ) and the angle A dc of the calibration plate cover 8 under the field of view of the down-view camera 1 are calculated. dc , Y dc ) of the calibration plate cover 8 under the field of view of the down-view camera 1 are calculated by formula (1):

[0038] (1)

[0039] Wherein, the meanings of the symbols in the above formula (1) are as follows:

[0040] (X bc , Y bc ) represents the pixel center of the calibration plate cover 8 under the field of view of the down-view camera 1; it should be noted that (X bc , Y bc ) is obtained by processing the image through a visual algorithm, the image is composed of a plurality of pixels, the upper left corner of the image is defaulted as the zero point of the pixel coordinate system, the right direction is the positive direction of the X axis, and the downward direction is the positive direction of the Y axis, after the rectangular contour of the calibration plate cover 8 is extracted by fitting the edge of the calibration plate cover 8 through the operator of the visual library, the pixel center coordinates of the calibration plate cover 8 can be calculated through the operator.

[0041] Width represents the width of the image of the downward-looking camera 1; it should be noted that Width represents how many pixels are in the horizontal direction of the image, i.e. the width of the pixel, which is an inherent attribute of the camera itself.

[0042] heigh represents the height of the image of the downward-looking camera 1; it should be noted that heigh represents how many pixels are in the vertical direction of the image, i.e. the height of the pixel, which is an inherent attribute of the camera itself.

[0043] Angle A of the calibration board cover 8 in the field of view of the downward-looking camera 1 dc , which is the angle between the diagonal of the rectangular calibration board cover 8 in the imaging in the field of view of the downward-looking camera 1 and the positive direction of the X axis. dc The calculation steps of the angle A dc are as follows:

[0044] Step 1.1, first, the rectangular contour of the calibration board cover 8 in the image of the downward-looking camera 1 is fitted by a visual algorithm;

[0045] Step 1.2, second, the center point coordinates, half width and half height of the rectangle in the rectangular contour in step 1.1 are output by using an operator encapsulated in the halcon visual library; the operator is gen_rectangle2_contour_xld (Operator);

[0046] Step 1.3, then, the four vertices of the rectangle are calculated by a trigonometric function relationship;

[0047] Step 1.4, then, after bubble sorting of the four vertices of the rectangle, the coordinates of the upper left point (x1, y1) and the lower right point (x2, y2) of the rectangle are obtained;

[0048] Step 1.5, finally, the angle A dc is calculated by formula (2):

[0049] A dc = arctan((y2-y1) / (x2-x1)) (2)

[0050] The calibration plate substrate 9 only has a practical effect in the first step, specifically, when the lower-view camera 1 acquires information of the calibration plate cover 8, the calibration plate substrate 9 plays a role of fixing the calibration plate cover 8 by vacuum suction, effectively avoiding the phenomenon that the calibration plate cover 8 may be displaced when the suction nozzle 2 moves. Specifically, the groove 6 of the calibration plate substrate 9 has a vacuum suction, in order to avoid displacement of the calibration plate substrate 9 when it is attached, the calibration plate substrate 9 is generally fixed in the groove 6 by double-sided tape; furthermore, since the groove 6 is metal, if the glass material calibration plate cover 8 is directly placed on it and sucked by the suction nozzle 2, it may cause scratches on the surface of the calibration plate cover 8, so the ceramic material calibration plate substrate 9 is used to protect the calibration plate cover 8 by placing a pad in the middle.

[0051] In the second step, the suction nozzle 2 sucks the calibration plate cover 8: the suction nozzle 2 moves to the upper surface of the calibration plate cover 8 to suck it, and records the current suction position of the suction nozzle; wherein the suction position is the system coordinate, in other words, it is the physical center coordinate of the lower-view camera 1 in the current suction state of the suction nozzle 2, or it can also be the physical center coordinate of the suction nozzle 2 in the current suction state of the suction nozzle 2. Since the lower-view camera 1 and the suction nozzle 2 move synchronously, there is only a fixed distance between the lower-view camera 1 and the suction nozzle 2, therefore, for the current suction state of the suction nozzle 2, when any one of the physical center coordinates of the lower-view camera 1 and the suction nozzle 2 is known, the other parameter can be obtained by conversion.

[0052] In the second step, the specific steps are: moving the suction nozzle 2 to 2-3 mm above the calibration plate cover 8, slowly lowering until the suction nozzle 2 presses on the surface of the calibration plate cover 8, then closing the first vacuum suction pump below the groove 6, at this time, the vacuum suction force of the groove 6 below the calibration plate substrate 9 disappears, and simultaneously opening the second vacuum suction pump matched with the suction nozzle 2, the suction nozzle 2 sucks the calibration plate cover 8 under the action of the second vacuum suction pump and records the current physical center coordinate (x2, y2) of the lower-view camera 1.

[0053] In the third step, after the suction nozzle 2 sucks the calibration plate cover 8, it moves to the upper-view camera 3 to take a picture, and obtains the physical center coordinate of the calibration plate cover 8: the suction nozzle 2 moves the sucked calibration plate cover 8 to the upper-view camera 3, the upper-view camera 3 takes a picture and records the coordinate of the motion controller at the time of taking the picture, calculates the physical center coordinate of the calibration plate cover 8 under the upper-view camera 3, and then calculates the current physical center coordinate of the upper-view camera 3.

[0054] Further, in the third step, the angle of the calibration plate cover 8 under the upper-view camera 3 is also calculated.

[0055] In the third step, the specific steps are: after the suction nozzle 2 sucks the calibration plate cover 8, the suction nozzle 2 moves to the upper-view camera 3 with the calibration plate cover 8 until the calibration plate cover 8 is clearly imaged, the upper-view camera 3 takes a picture upward of the calibration plate cover 8, calculates the physical center coordinates (X dc ’ , Y dc ’ ) and the angle A dc ’ of the calibration plate cover 8 in the field of view of the upper-view camera, and calculates the current physical center coordinates (x3, y3) of the upper-view camera. It should be noted that the calibration plate cover 8 can be calculated through the relative coordinates before and after the shaft movement no matter where it is moved by the suction nozzle. The final purpose of calculating the center of the calibration plate cover 8 is to derive the center of the upper-view camera 3 from the center of the calibration plate cover 8 at the imaging position of the upper-view camera 3. Once the center of the upper-view camera 3 is known, the center of the lower-view camera 1 is also known (read by the motion controller), so the positional relationship between the two cameras can be known.

[0056] Specifically, the physical center coordinates (X dc ', Y dc ) of the calibration plate cover 8 in the field of view of the upper-view camera 3 are calculated through formula (3):

[0057]

[0058] After the physical center coordinates of the calibration plate cover 8 above the upper-view camera 3 are calculated, when the upper-view camera 3 takes a picture of the calibration plate cover 8, the physical deviation between the center of the calibration plate cover 8 and the image center can be calculated through visual algorithm processing of the image, and the current physical center coordinates of the upper-view camera 3 are calculated. After the physical center coordinates of the upper-view camera 3 are calculated, the physical coordinates of the center of the lower-view camera 1 can be read by the motion controller, and thus the positional relationship between the lower-view camera 1 and the upper-view camera 3 can be known.

[0059] Specifically, the pixel center coordinates of the calibration plate cover 8 in the image of the upper-view camera 3 (obtained by processing the image by visual algorithm), the physical center coordinates of the calibration plate cover 8 above the upper-view camera 3, and the image center pixel coordinates of the upper-view camera (image width / 2, image height / 2) are known. Here, in order to facilitate expression, the physical center coordinates of the calibration plate cover 8 above the upper-view camera 3 are set as C physics1 , the current physical center coordinates of the upper-view camera are set as C physics2 , the pixel center coordinates of the calibration plate cover 8 in the image of the upper-view camera 3 are set as C pixel1 , and the image center pixel coordinates of the upper-view camera are set as C pixel2 , then:

[0060] C physics1- C physics2 = C pixel1 - C pixel2 (4)

[0061] The formula (4) is derived into formula (5):

[0062] C physics2 = C physics1 - C pixel1 + C pixel2 (5)

[0063] Then through the above formula (5), the current physical center coordinates of the upward-looking camera can be obtained.

[0064] The angle A of the cover 8 of the calibration board under the field of view of the upward-looking camera 3 dc ， The angle A dc ， refers to the angle between the diagonal line of the cover 8 of the calibration board in the imaging field of view of the upward-looking camera 3 and the positive direction of the X axis. The angle A dc ’ is calculated as follows:

[0065] Step 3.1, first, the rectangular contour of the cover 8 of the calibration board in the image of the downward-looking camera 1 is fitted through a visual algorithm;

[0066] Step 3.2, second, the center point coordinates, half width and half height of the rectangle in step 3.1 are output using the operator encapsulated in the halcon visual library; wherein the operator is gen_rectangle2_contour_xld(Operator);

[0067] Step 3.3, then, the four vertices of the rectangle are calculated through a trigonometric function relationship;

[0068] Step 3.4, then, after bubble sorting the four vertices of the rectangle, the left upper point coordinates (x1 ’ , y1 ’ ) and the right lower point coordinates (x2 ’ , y2 ’ ) of the rectangle are obtained;

[0069] Step 3.5, finally, the angle A dc ， is calculated through formula (4):

[0070] A dc ， =arctan((y2 ’ -y1 ’ ) / (x2 ’ -x1 ’)) (4)

[0071] Step 4, the position relationship between the downward-looking camera and the upward-looking camera is derived by calibrating the position relationship of the cover 8 of the calibration board between the downward-looking camera and the upward-looking camera: according to the physical center coordinates (X dc , Y dc ) of the cover 8 of the calibration board under the downward-looking camera 1, the physical center coordinates (X dc ’ , Y dc ’ ) of the cover 8 of the calibration board under the upward-looking camera 3, and the distance of the suction nozzle 2 sucking the cover 8 of the calibration board moving to the upward-looking camera 3, the position relationship between the downward-looking camera 1 and the upward-looking camera 3 is calculated. Specifically, the position relationship between the downward-looking camera and the upward-looking camera is calculated by formula (5) and formula (6), that is, the position relationship between the downward-looking camera 1 and the upward-looking camera 3 is calculated:

[0072] (5)

[0073] Wherein, the meanings of the symbols in the above formula (5) are as follows:

[0074] (X uc , Y uc ) represents the physical center coordinates of the upward-looking camera 3; it should be noted that (X uc , Y uc ) is obtained by processing the image by a visual algorithm, and the image is composed of a plurality of pixels, and the upper left corner of the image is taken as the zero point of the pixel coordinate system by default, the right is the positive direction of the X axis, and the downward is the positive direction of the Y axis. After the rectangular contour of the cover 8 of the calibration board is extracted by calling the edge fitting operator of the visual library, the pixel center coordinates of the cover 8 of the calibration board can be calculated by the operator.

[0075] (X bc ’ , Y bc ’ ) represents the pixel center of the cover 8 of the calibration board under the field of view of the upward-looking camera 3;

[0076] width ’ represents the image width of the upward-looking camera 3; it should be noted that width ’ represents the number of pixels in the horizontal direction of the image, that is, the width of the pixel, which is a inherent property of the camera itself.

[0077] heigh ’ represents the image height of the upward-looking camera 3; it should be noted that heigh ’How many pixels are there in the vertical direction of the image, that is, the height of the pixels, which is an inherent property of the camera itself.

[0078] (6)

[0079] In the above formula (6), the meaning of each symbol is as follows:

[0080] A represents the installation angle deviation between the downward-looking camera and the upward-looking camera.

[0081] The position relationship calibration method between the two opposite cameras of the present application obtains the physical center coordinates of the calibration board cover 8 by taking a picture of the calibration board cover 8 through the downward-looking camera 1, moves the suction nozzle 2 to the upward-looking camera 3 after sucking the calibration board cover 8, and takes a picture to obtain the physical center coordinates of the calibration board cover 8. According to the physical center coordinates of the calibration board cover 8 under the downward-looking camera 1, the physical center coordinates of the calibration board cover 8 under the upward-looking camera 3, and the distance of the suction nozzle 2 sucking the calibration board cover 8 moving to the upward-looking camera 3, the position relationship between the downward-looking camera 1 and the upward-looking camera 3 is calculated. This method is particularly suitable for the double-camera relationship calibration before the surface packaging placement machine based on machine vision. In the placement process of the placement machine, the position relationship between the downward-looking camera 1 and the upward-looking camera 3 can be more accurately calculated, and the calibration influence caused by the shape of the suction nozzle 2 and the verticality difference of the suction nozzle 2 axis can be completely eliminated.

[0082] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for calibrating the position relationship between two different cameras, characterized in that, The lower-view camera moves with the suction nozzle, and a fixed distance L exists between the physical center of the lower-view camera and the physical center of the suction nozzle; The position relationship calibration method comprises the following steps: In the first step, the lower-view camera photographs the calibration plate cover to obtain the physical center coordinates of the calibration plate cover: the lower-view camera is moved above the calibration plate cover, the lower-view camera photographs and records the current physical center coordinates of the lower-view camera, and the physical center coordinates of the calibration plate cover under the lower-view camera are calculated; In the second step, the suction nozzle sucks the calibration plate cover: the suction nozzle is moved to the upper surface of the calibration plate cover to suck, and the current suction position of the suction nozzle is recorded; Step 3, the nozzle sucks the calibration plate cover and moves to the upper camera to take a picture, and the physical center coordinates of the calibration plate cover are obtained: the nozzle moves the calibration plate cover sucked to the upper camera, the upper camera takes a picture and records the coordinates of the motion controller at the time of taking the picture, calculates the physical center coordinates of the calibration plate cover under the upper camera, and calculates the current physical center coordinates of the upper camera; the specific steps are: after the nozzle sucks the calibration plate cover, the nozzle moves the calibration plate cover to the upper camera until the calibration plate cover is clearly imaged, the upper camera takes a picture of the calibration plate cover, calculates the physical center coordinates (X dc ’ , Y dc ’ ) and angle A dc ’ of the calibration plate cover under the upper camera, and calculates the current physical center coordinates (x3, y3) of the upper camera; the calculation steps of the current physical center coordinates (x3, y3) of the upper camera are: the physical center coordinates (X dc , Y dc ) of the calibration plate cover under the lower camera are known, the nozzle moves the calibration plate cover to above the upper camera, the starting position axis coordinates of the nozzle sucking the calibration plate cover are set as m, the end position axis coordinates of the nozzle moving the calibration plate cover to above the upper camera are set as n, the distance of the nozzle moving the calibration plate cover to the upper camera is calculated as n-m, and then the physical center coordinates of the calibration plate cover above the upper camera are calculated, that is, the physical center coordinates (x3, y3) of the calibration plate cover above the upper camera are equal to the physical center coordinates (X dc , Y dc ) of the calibration plate cover under the lower camera, the distance of the nozzle moving to the calibration plate cover, and the distance n-m of the nozzle moving the calibration plate cover to the upper camera. In the fourth step, the position relationship between the lower-view camera and the upper-view camera is derived through the position relationship of the calibration plate cover between the lower-view camera and the upper-view camera: the position relationship between the lower-view camera and the upper-view camera is calculated according to the physical center coordinates of the calibration plate cover under the lower-view camera, the physical center coordinates of the calibration plate cover under the upper-view camera, and the distance of the suction nozzle sucking the calibration plate cover moving to the upper-view camera.

2. The position relationship calibration method between the two different cameras according to claim 1, wherein: In the first step, the angle of the calibration plate cover under the lower-view camera is also calculated; In the third step, the angle of the calibration plate cover under the upper-view camera is also calculated.

3. The method of calibrating the position relationship between the two different direction cameras according to claim 1 or 2, characterized in that: The position relationship calibration method also uses a base and a first vacuum adsorption pump, and the upper surface of the base is provided with a groove, and a plurality of adsorption holes connected with the first vacuum adsorption pump are arranged at the position corresponding to the groove along the height direction of the base.

4. The method of claim 3, wherein: The calibration plate cover is made of glass, and the position relationship calibration method also uses a calibration plate substrate made of ceramic.

5. The method of claim 4, wherein, In the first step, the specific steps are: placing the calibration plate substrate in the groove, placing the calibration plate cover on the upper surface of the calibration plate substrate, turning on the first vacuum suction pump below the groove, and then the suction holes in the groove tightly suck the calibration plate cover through the through holes on the calibration plate substrate by the suction force generated by the first vacuum suction pump, the downward-looking camera is moved to the clear imaging position above the calibration plate cover to take a photo, and the current physical center coordinates (x1, y1) of the downward-looking camera are recorded, the physical center coordinates (X dc , Y dc ) and the angle A dc of the calibration plate cover in the field of view of the downward-looking camera are calculated.

6. The method of claim 5, wherein, In the second step, the specific steps are as follows: the suction nozzle is moved to 2-3 mm above the calibration plate cover, slowly lowered until the suction nozzle is pressed on the surface of the calibration plate cover, then the first vacuum adsorption pump below the groove is turned off, at this time, the vacuum adsorption force of the groove below the calibration plate substrate disappears, and the second vacuum adsorption pump matched with the suction nozzle is turned on, the suction nozzle sucks the calibration plate cover under the action of the second vacuum adsorption pump and records the current physical center coordinates (x2, y2) of the lower-view camera.

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