CN113804128A - Double-bearing-hole coaxiality error visual measurement device and measurement method - Google Patents
Double-bearing-hole coaxiality error visual measurement device and measurement method Download PDFInfo
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Abstract
The invention discloses a double-bearing-hole coaxiality error vision measuring device and method, and belongs to the technical field of machine vision measurement. The method comprises the steps of fitting a first axis equation by utilizing a first vision measurement unit to collect end surface point cloud data of a first bearing hole; acquiring end surface point cloud data of the second bearing hole by using a second vision measuring unit to fit a second axis equation; and converting the obtained first axis equation and the second axis equation into a unified coordinate system by combining the relative position relationship of the first vision measuring unit and the second vision measuring unit to obtain the coaxiality error evaluation parameter of the double bearing holes. The device comprises a first vision measuring unit and a second vision measuring unit which are used for obtaining end surface point cloud data, a calibration unit which is used for calibrating the relative position relation of the first vision measuring unit and the second vision measuring unit, and a data processing unit which is used for processing to obtain a coaxiality error evaluation parameter. The method is simple and efficient to operate and suitable for measuring the coaxiality of the large-span bearing hole.
Description
Technical Field
The invention belongs to the technical field of machine vision measurement, and particularly relates to a double-bearing-hole coaxiality error vision measurement device and a measurement method.
Background
The coaxiality error directly influences the precision and reliability of transmission, so that the additional load in the transmission process is increased, the vibration noise is high, and the normal operation of equipment is seriously influenced. The existing coaxiality measuring method belongs to indirect measurement and comprises a rotation axis method, a collimation method, a coordinate method, an analog method, a function gauge detection method and the like, and the methods can basically meet the coaxiality measuring requirement of common hole parts, but have the defects of complex operation, low efficiency and difficulty in on-line measurement, and cannot meet the actual production requirement of enterprises.
The machine vision measurement technology has the advantages of non-contact, flexibility, high precision and the like, and the automation of the measurement process can be realized by introducing the machine vision measurement technology into a coaxiality measurement system, so that the human errors are reduced, and the measurement precision is improved. However, the coaxiality measurement method based on machine vision is not widely applied in enterprise production at present, and is limited by the depth of field, the field of view, the dead zone and the like of an industrial camera, and most of the existing vision measurement methods cannot fit the axis equations of the two bearing holes by using a uniform measurement coordinate system. Especially for the coaxiality measurement of the large-span coaxial hole, the method is a difficult problem in the production of mechanical manufacturing enterprises.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a double-bearing-hole coaxiality error vision measuring device and a measuring method, which are simple and efficient to operate, high in measuring speed and precision, strong in environmental adaptability, capable of realizing online measurement in an industrial field and particularly suitable for measuring the coaxiality of a large-span bearing hole.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a visual measurement method for coaxiality error of a double-bearing hole, which comprises the following steps of:
s1, adjusting the first vision measuring unit to enable the first bearing hole to be clearly imaged, and adjusting the second vision measuring unit to enable the second bearing hole to be clearly imaged; s2, calibrating the first vision measuring unit and the second vision measuring unit by using the target to obtain the relative position relation between the first vision measuring unit and the second vision measuring unit; s3, acquiring end surface point cloud data of the first bearing hole by using the first vision measuring unit, calculating the circle center coordinate and the end surface normal of the first bearing hole on the end surface, and further fitting a first axis equation; acquiring end surface point cloud data of the second bearing hole by using a second vision measuring unit, calculating the circle center coordinate and the end surface normal of the second bearing hole on the end surface, and further fitting a second axis equation; and S4, converting the first axis equation and the second axis equation obtained in S3 into a unified coordinate system by combining the relative position relationship between the first vision measuring unit and the second vision measuring unit obtained in S2, and obtaining the coaxiality error evaluation parameter of the double-bearing hole.
Preferably, in S2, the target is formed by four sub-targets being fixedly connected; wherein the first sub-target is located within the field of view of the first vision measuring unit; the fourth sub-target is positioned in the field of view range of the second vision measuring unit; and the third sub-target is fixedly connected with the fourth sub-target.
Preferably, in S2, the first vision measuring unit and the second vision measuring unit are calibrated by using the target, and the relative position relationship between the first vision measuring unit and the second vision measuring unit is obtained, which includes the following steps:
s201, calibrating a large-view-field camera, and then acquiring pictures of a first sub-target and a second sub-target in the same view field and pictures of a third sub-target and a fourth sub-target in the same view field by using the large-view-field camera; calibrating the large-view-field camera again, and then acquiring the pictures of the second sub-target and the third sub-target in the same view field; solving the rotation matrix R of the first sub-target and the second sub-target by utilizing the external parameters of each sub-target and the large-view-field camera12Rotation matrix R of the second sub-target and the third sub-target23A third sub-target and a fourth sub-targetRotation matrix R of quadruplicate targets34Translation matrix T of first sub-target and second sub-target12Translation matrix T of second sub-target and third sub-target23Translation matrix T of third sub-target and fourth sub-target34(ii) a And then solving a rotation matrix R of the first sub-target and the fourth sub-target14And a translation matrix T of the first sub-target and the fourth sub-target14(ii) a S202, acquiring a first sub-target picture by using a first vision measuring unit, and acquiring a fourth sub-target picture by using a second vision measuring unit; solving a rotation matrix R of the first sub-target and the first vision measurement unit by utilizing a PnP principleb1s1A rotation matrix R of the fourth sub-target and the second vision measuring unitb4s2Translation matrix T of first sub-target and first vision measurement unitb1s1Translation matrix T of fourth sub-target and second vision measurement unitb4s2(ii) a S203, rotation matrix R solved by S20114And translation matrix T14And the rotation matrix R solved in S202b1s1Translation matrix Tb1s1A rotation matrix Rb4s2And translation matrix Tb4s2Solving the rotation matrix R of the first vision measuring unit and the second vision measuring units1s2Translation matrix T with first and second vision measuring unitss1s2。
Further preferably, parameters of the large-field-of-view camera and the PnP principle are utilized to respectively solve the parameters of each sub-target and the external parameters of the large-field-of-view camera.
Preferably, for the deep bearing hole, the axis equation of the bearing hole is calculated by adopting a least square fitting method through collecting point cloud data of the cylindrical surface in the bearing hole.
Preferably, the double-bearing-hole coaxiality error visual measurement method is suitable for a Visio Studio or Matlab platform.
Preferably, the obtained coaxiality error evaluation parameters of the double bearing holes comprise the spatial distance and the included angle of the two axes.
The invention discloses a double-bearing-hole coaxiality error visual measurement device which comprises a first visual measurement unit, a second visual measurement unit, a calibration unit and a data processing unit, wherein the first visual measurement unit is used for measuring the coaxiality error of a bearing hole; the first vision measuring unit is used for acquiring end surface point cloud data of the first bearing hole; the second vision measuring unit is used for acquiring end surface point cloud data of the second bearing hole; the calibration unit is used for calibrating the relative position relationship between the first vision measurement unit and the second vision measurement unit; the data processing unit is used for processing the obtained relative position relation and the end face point cloud data to obtain the coaxiality error evaluation parameters of the double-bearing hole.
Preferably, the first vision measuring unit and the second vision measuring unit employ a structured light vision measuring unit.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a visual measurement method for coaxiality errors of double bearing holes. Therefore, the double-bearing-hole coaxiality error visual measurement method has the advantages of simplicity and high efficiency in operation, high measurement speed and high precision. Meanwhile, the method is suitable for various industrial operation environments, can realize online measurement on an industrial site, and effectively solves the technical problem of coaxiality measurement of the large-span bearing hole.
Furthermore, the target formed by fixedly connecting the four sub-targets serves as a multi-calibration-plate fixedly-connected target, the position relations between the vision measuring units and the corresponding sub-targets and between every two sub-targets are sequentially calibrated, the position relation between the two vision measuring units can be obtained, the measuring precision is improved, and the problem that two sub-targets back to each other cannot appear in the same view field is solved.
The invention discloses a double-bearing-hole coaxiality error visual measurement device which is suitable for measuring coaxiality errors of all double-bearing-hole parts, particularly suitable for measuring coaxiality of a large-span bearing hole and has universality; the vision measurement unit can complete data acquisition within 1 second, is simple and efficient to operate and has good environmental adaptability; by adopting the structured light vision measuring unit, more point cloud data can be collected, and the axis fitting precision is good; after the system calibration is completed once, the parts with the same specification can be measured on line in batches.
Drawings
FIG. 1 is a schematic diagram of a double-bearing-hole coaxiality error visual measurement device and a measurement method thereof according to the present invention;
FIG. 2 is a schematic diagram of a system calibration method according to the present invention;
FIG. 3 is an end face image of a bearing hole of a road roller vibrating wheel acquired by a line laser scanning binocular vision measuring unit according to an embodiment of the present invention;
FIG. 4 shows the measurement result of the coaxiality error of the road roller vibrating wheel in the embodiment of the invention.
Wherein: 1-a first bearing bore; 2-second bearing hole; 3-a first vision measurement unit; 4-a second vision measurement unit; 5-a first lifting frame; 6-a second lifting frame; 7-a first sub-target; 8-a second sub-target; 9-a third sub-target; 10-a fourth sub-target; 11-large field of view camera.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. 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.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention discloses a double-bearing-hole coaxiality error visual measurement device which comprises a first visual measurement unit 3 and a second visual measurement unit 4 which are oppositely arranged on two sides of a first bearing hole 1 and a second bearing hole 2 to be measured, wherein the first visual measurement unit 3 and the second visual measurement unit 4 are respectively arranged on a first lifting frame 5 and a second lifting frame 6 which can be pushed forwards and backwards and can move left and right through a tripod head. The first vision measuring unit 3 is used for acquiring end surface point cloud data of the first bearing hole 1; the second vision measuring unit 4 is used for acquiring end surface point cloud data of the second bearing hole 2. The double-bearing-hole coaxiality error vision measuring device further comprises a calibration unit and a data processing unit. The calibration unit is used for calibrating the relative position relationship between the first vision measurement unit 3 and the second vision measurement unit 4; the data processing unit is used for processing the obtained relative position relation, unifying the obtained end face point cloud data to a coordinate system, and further calculating to obtain coaxiality error evaluation parameters of the double bearing holes.
Specifically, in a specific embodiment of the present invention, the calibration unit comprises a target and a large field of view camera 11. Wherein, the target is formed by four sub-targets which are mechanically connected and connected: the first sub-target 7 is located within the field of view of the first vision measuring unit 3; the fourth sub-target 10 is located within the field of view of the second vision measuring unit 4; the first sub-target 7 is fixedly connected with the second sub-target 8, and the third sub-target 9 is fixedly connected with the fourth sub-target 10. The fixed connection included angle between the first sub-target 7 and the second sub-target 8 is within the range that the first sub-target can be clearly imaged in the large-field camera and the first sub-target can be clearly imaged in the first vision measuring unit; the fixed connection included angle between the third sub-target 9 and the fourth sub-target 10 is within the range that the third sub-target can be clearly imaged in the large-field-of-view camera and the fourth sub-target can be clearly imaged in the second vision measuring unit at the same time.
Preferably, the fixed connection included angle between the first sub-target 7 and the second sub-target 8 is 90 °; the fixed connection included angle between the third sub-target 9 and the fourth sub-target 10 is 90 °.
Specifically, in one embodiment of the present invention, the data processing unit may use a Visio Studio or Matlab platform.
Specifically, in a specific embodiment of the present invention, the lens of the vision measuring unit may be replaced, the measuring distance may be adjusted, and the like for bearing holes of different specifications.
Wherein, the vision measuring units (including the first vision measuring unit 3 and the second vision measuring unit 4) adopt structured light vision measuring units.
Specifically, for a surface of higher reflectivity (smooth metal surface), a line laser scanning vision measuring unit may be used, and for a general diffuse reflection surface (rough metal surface), a grating stripe projection vision measuring unit may be used.
The double-bearing-hole coaxiality error visual measurement device can realize online measurement on an industrial site, and is particularly suitable for measuring the coaxiality of a large-span bearing hole, and the measurement method of the double-bearing-hole coaxiality error visual measurement device comprises the following steps:
s1, building the double-bearing-hole coaxiality error vision measuring device of claim 1, and adjusting the first vision measuring unit 3 and the second vision measuring unit 4 to enable the first bearing hole 1 and the second bearing hole 2 to be measured to be clearly imaged in the visual field range of the vision measuring units corresponding to the first bearing hole 1 and the second bearing hole 2 respectively;
s2, calibrating a multi-vision system without a common visual field, which is composed of two sets of vision measuring units (a first vision measuring unit 3 and a second vision measuring unit 4) which are oppositely arranged, by using a target to obtain a relative position relationship between the first vision measuring unit 3 and the second vision measuring unit 4;
s3, the first vision measuring unit 3 obtains point cloud data of the end face of the first bearing hole 1, and the circle center of the first bearing hole 1 on the end face and the normal line of the end face are fitted; the second vision measuring unit 4 acquires point cloud data of the end face of the second bearing hole 2, and fits the circle center of the second bearing hole 2 on the end face and the normal line of the end face; therefore, bearing hole axis equations (respectively recorded as a first axis equation and a second axis equation) of two different coordinate systems are respectively calculated;
and S4, converting the axis equations of the bearing holes of two different coordinate systems respectively measured by the two sets of vision measuring units into a unified coordinate system according to the calibration result of S2 (namely, the calibration result is the relative position relationship between the first vision measuring unit 3 and the second vision measuring unit 4), and giving out coaxiality error evaluation parameters which comprise the spatial distance and the included angle of the two axes.
Specifically, the target for calibration in step S2 is formed by mechanically and fixedly connecting four sub-targets (a first sub-target 7, a second sub-target 8, a third sub-target 9, and a fourth sub-target 10), the first sub-target 7 is located in the field of view of the first vision measuring unit 3, the fourth sub-target 10 is located in the field of view of the second vision measuring unit 4, the first sub-target 7 and the second sub-target 8, and the third sub-target 9 and the fourth sub-target 10 are respectively fixed at a certain angle (the fixed connection angle between the first sub-target 7 and the second sub-target 8 is within a range in which the large-field camera can clearly image and the first sub-target is clearly imaged in the first vision measuring unit at the same time; the fixed connection angle between the third sub-target 9 and the fourth sub-target 10 is within a range in which the large-field camera can clearly image and the fourth sub-target is clearly imaged in the second vision measuring unit at the same time), in step S2, calibrating the first vision measuring unit 3 and the second vision measuring unit 4 by using the target to obtain the relative position relationship between the first vision measuring unit 3 and the second vision measuring unit 4, which includes the following specific steps:
s201, calibrating a large-view-field camera 11, and respectively moving the large-view-field camera 11 to acquire pictures of the first sub-target 7 and the second sub-target 8 in the same view field and pictures of the third sub-target 9 and the fourth sub-target 10 in the same view field; calibrating the large-view-field camera 11 again, and acquiring the pictures of the second sub-target 8 and the third sub-target 9 in the same view field; the parameters of the large-view-field camera 11 and the PnP principle can be used for respectively solving the external parameters of each sub-target and the large-view-field camera 11, and then the first sub-target 7, the second sub-target 8 and the second sub-target are solvedRotation matrices between 8 and the third sub-target 9, the third sub-target 9 and the fourth sub-target 10 (rotation matrices R of the first sub-target 7 and the second sub-target 8)12Rotation matrix R of the second sub-target 8 and the third sub-target 923A rotation matrix R of the third sub-target 9 and the fourth sub-target 1034) And a translation matrix (translation matrix T of the first sub-target 7 and the second sub-target 8)12Translation matrix T of second sub-target 8 and third sub-target 923Translation matrix T of the third sub-target 9 and the fourth sub-target 1034) And then solving the rotation matrix R of the first sub-target 7 and the fourth sub-target 1014And a translation matrix T of the first sub-target 7 and the fourth sub-target 1014(ii) a (as a relative positional relationship between the first vision measuring unit 3 and the second vision measuring unit 4)
S202, the first vision measuring unit 3 acquires a first sub-target 7 picture, the second vision measuring unit 4 acquires a fourth sub-target 10 picture, and a rotation matrix (a rotation matrix R of the first sub-target 7 and the first vision measuring unit 3) between the first sub-target 7 and the first vision measuring unit 3 and between the fourth sub-target 10 and the second vision measuring unit 4 is solved by utilizing a PnP principleb1s1A fourth sub-target 10 and a rotation matrix R of the second vision measuring unit 4b4s2) And the translation matrix (the translation matrix T of the first sub-target 7 and the first vision measuring unit 3)b1s1A fourth sub-target 10 and a translation matrix T of the second vision measuring unit 4b4s2)；
S203, utilizing the rotation matrix R between the first sub-target 7 and the fourth sub-target 10 solved in the step S20114And translation matrix T14The rotation matrix R between the first vision measuring unit 3 and the first sub-target 7 solved in step S202b1s1And translation matrix Tb1s1And a rotation matrix R between the second vision measuring unit 4 and the fourth sub-target 10b4s2And translation matrix Tb4s2Finally, the rotation matrix between the first vision measuring unit 3 and the second vision measuring unit 4 (the rotation matrix R of the first vision measuring unit 3 and the second vision measuring unit 4) is solveds1s2) And a translation matrix (translation matrix T of the first vision measuring unit 3 and the second vision measuring unit 4)s1s2)，Rs1s2And Ts1s2The derivation process is as follows:
wherein (x)wi，ywi，zwi) To correspond to the world coordinate system coordinates of calibration plate i, (x)si，ysi，zsi) Is the coordinate under the camera coordinate system of the corresponding vision measurement unit i.
Further, in step S3, when the bearing hole is deep, the axis equation of the bearing hole may be calculated by collecting point cloud data of the cylindrical surface inside the bearing hole and using a least squares fit method.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Examples
The invention provides a double-bearing-hole coaxiality error visual measurement device and a measurement method thereof, and the specific implementation mode is as follows:
firstly, as shown in fig. 1, a first vision measuring unit 3 and a second vision measuring unit 4 are oppositely arranged on two sides of a first bearing hole 1 and a second bearing hole 2 of a workpiece, and are respectively arranged on a first lifting frame 5 and a second lifting frame 6 which can be pushed forwards and backwards and can translate left and right through a pan-tilt, according to the positions and the sizes of the two bearing holes, a proper lens is selected, and the pose of the vision measuring unit is adjusted, so that the vision measuring unit can completely collect an end face image containing the bearing holes; in the embodiment, the image obtained by scanning the binocular vision measuring unit by using the line laser is as shown in fig. 3;
secondly, calibrating a multiple vision system without a public view field, which is composed of two sets of vision measuring units arranged oppositely, to obtain a relative position relationship between the two vision measuring units, as shown in fig. 2, wherein a target for calibration is formed by mechanically and fixedly connecting four targets (a first sub-target 7, a second sub-target 8, a third sub-target 9 and a fourth sub-target 10), the first sub-target 7 is located in the view field range of the vision measuring unit 1, the second sub-target 8 is located in the view field range of the vision measuring unit 2, and the first sub-target 7 and the second sub-target 8, and the third sub-target 9 and the fourth sub-target 10 are fixedly connected with each other at an included angle of 90 degrees; the distance between the first sub-target 7 and the fourth sub-target 10 is adjustable and is equivalent to the distance between the bearing holes to be measured; as shown in fig. 2, the specific calibration steps are as follows:
1) calibrating a large-view-field camera 11, and respectively moving the large-view-field camera 11 to acquire pictures of the first sub-target 7 and the second sub-target 8 in the same view field and pictures of the third sub-target 9 and the fourth sub-target 10 in the same view field; calibrating the large-view-field camera 11 again, and acquiring the pictures of the second sub-target 8 and the third sub-target 9 in the same view field; the parameters of the large-field-of-view camera 11 and the PnP can be used to respectively solve the external parameters of each sub-target and the large-field-of-view camera 11, and further to solve the rotation matrix (R) between the first sub-target 7 and the second sub-target 8, between the second sub-target 8 and the third sub-target 9, and between the third sub-target 9 and the fourth sub-target 1012、R23、R34) And a translation matrix (T)12、T23、T34) And then solving a rotation matrix (R) between the first sub-target 7 and the fourth sub-target 1014) And a translation matrix (T)14)；
2) In the embodiment, line laser scanning is adopted for binocular vision measurement units, and the inside and outside parameters of the first vision measurement unit 3 and the second vision measurement unit 4 are calibrated by using a binocular calibration method;
3) fixing the pose relationship between the first vision measuring unit 3 and the second vision measuring unit 4, simultaneously acquiring a first sub-target 7 picture by the first vision measuring unit 3 and a fourth sub-target 10 picture by the second vision measuring unit 4 respectively, and solving the rotation (R) between the first sub-target 7 and the first vision measuring unit 3 and between the fourth sub-target 10 and the second vision measuring unit 4 by utilizing the PnP principleb1s1、Rb4s2) And translation matrix (T)b1s1、Tb4s2)；
4) Finally, the rotation (R) between the first vision measuring unit 3 and the second vision measuring unit 4 is solved by using the rotation matrix and the translation matrix between the first sub-target 7 and the fourth sub-target 10 solved in the step 1), the rotation matrix and the translation matrix between the first vision measuring unit 3 and the first sub-target 7 solved in the step 3), and the rotation matrix and the translation matrix between the second vision measuring unit 4 and the fourth sub-target 10s1s2) And translation matrix (T)s1s2)，Rs1s2And Ts1s2The derivation process is as follows:
then, calculating by adopting a three-dimensional reconstruction algorithm commonly used in the technical field to obtain end surface three-dimensional point cloud data, fitting the circle center coordinates of the bearing holes on the end surface and the end surface normal, and respectively calculating to obtain an axis equation of the two bearing holes; when the bearing hole is deep, point cloud data of the cylindrical surface in the bearing hole can be collected, and then the axis can be directly fitted.
And finally, according to the coordinate system rotation and translation matrix between the two vision measurement units obtained by calibration, converting axis equations of two different coordinate systems respectively measured by the two vision measurement units into a unified coordinate system, and giving the space distance and the included angle of the two axes as shown in FIG. 4.
In conclusion, the invention discloses a double-bearing-hole coaxiality error visual measurement device and a measurement method thereof, belongs to the field of machine visual measurement, and aims to solve the problem of coaxiality error measurement of shaft hole parts in actual production and manufacturing. The visual measurement device for the coaxiality error of the double bearing holes is characterized in that the visual measurement device for the coaxiality error of the double bearing holes provided by the invention is built: firstly, adjusting a measuring device at a proper position according to the size and the pitch of a measured bearing hole, then calibrating internal and external parameters of a vision measuring unit by using the calibration method provided by the invention, respectively collecting point cloud data of end faces of two bearing holes by the vision measuring unit, calculating the circle center coordinate and the end face normal of the bearing hole at the end face, further fitting the axes of the two bearing holes, and finally unifying the two fitted axes to a coordinate system according to the external parameters of the two vision measuring units calibrated by the system to give out coaxiality error evaluation parameters. The method has the advantages of simple and efficient operation, high measurement speed, high precision and strong environmental adaptability, can realize online measurement in an industrial field, and is particularly suitable for measuring the coaxiality of the large-span bearing hole.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (9)
1. A visual measurement method for coaxiality error of a double-bearing hole is characterized by comprising the following steps:
s1, adjusting the first vision measuring unit (3) to enable the first bearing hole (1) to be imaged clearly, and adjusting the second vision measuring unit (4) to enable the second bearing hole (2) to be imaged clearly;
s2, calibrating the first vision measuring unit (3) and the second vision measuring unit (4) by using the target to obtain the relative position relation between the first vision measuring unit (3) and the second vision measuring unit (4);
s3, acquiring end surface point cloud data of the first bearing hole (1) by using the first vision measuring unit (3), calculating the circle center coordinate and the end surface normal of the first bearing hole (1) on the end surface, and further fitting a first axis equation; acquiring end surface point cloud data of the second bearing hole (2) by using a second vision measuring unit (4), calculating the circle center coordinate and the end surface normal of the second bearing hole (2) on the end surface, and further fitting a second axis equation;
and S4, combining the relative position relation between the first vision measuring unit (3) and the second vision measuring unit (4) obtained in S2, and converting the first axis equation and the second axis equation obtained in S3 into a unified coordinate system to obtain the coaxiality error evaluation parameters of the double bearing holes.
2. The visual measurement method for the coaxiality error of the double bearing holes as claimed in claim 1, wherein in S2, the target is formed by fixedly connecting four sub-targets;
wherein the first sub-target (7) is located within the field of view of the first vision measuring unit (3); the fourth sub-target (10) is positioned in the field of view of the second vision measuring unit (4);
the first sub-target (7) is fixedly connected with the second sub-target (8), and the third sub-target (9) is fixedly connected with the fourth sub-target (10).
3. The visual measurement method for coaxiality error of double bearing holes of claim 1, wherein in step S2, the first visual measurement unit (3) and the second visual measurement unit (4) are calibrated by using the target, so as to obtain the relative position relationship between the first visual measurement unit (3) and the second visual measurement unit (4), and the steps are as follows:
s201, calibrating a large-view-field camera (11), and then acquiring pictures of a first sub-target (7) and a second sub-target (8) in the same view field and pictures of a third sub-target (9) and a fourth sub-target (10) in the same view field by using the large-view-field camera (11); calibrating the large-view-field camera (11) again, and then acquiring pictures of the second sub-target (8) and the third sub-target (9) in the same view field;
solving a rotation matrix R of the first sub-target (7) and the second sub-target (8) by utilizing the external parameters of each sub-target and the large-field-of-view camera (11)12A rotation matrix R of the second sub-target (8) and the third sub-target (9)23A rotation matrix R of the third sub-target (9) and the fourth sub-target (10)34A translation matrix T of the first sub-target (7) and the second sub-target (8)12A translation matrix T of the second sub-target (8) and the third sub-target (9)23A translation matrix T of the third sub-target (9) and the fourth sub-target (10)34(ii) a Then, the rotation matrix R of the first sub-target (7) and the fourth sub-target (10) is solved14And a translation matrix T of the first sub-target (7) and the fourth sub-target (10)14；
S202, acquiring a first sub-target (7) picture by using a first vision measuring unit (3), and acquiring a fourth sub-target (10) picture by using a second vision measuring unit (4); solving a rotation matrix R of the first sub-target (7) and the first vision measurement unit (3) by utilizing the PnP principleb1s1A fourth sub-target (10) and a rotation matrix R of the second vision measuring unit (4)b4s2A translation matrix T of the first sub-target (7) and the first vision measuring unit (3)b1s1A translation matrix T of a fourth sub-target (10) and a second vision measuring unit (4)b4s2；
S203, rotation matrix R solved by S20114And translation matrix T14And the rotation matrix R solved in S202b1s1Translation matrix Tb1s1A rotation matrix Rb4s2And translation matrix Tb4s2Solving a rotation matrix R of the first vision measuring unit (3) and the second vision measuring unit (4)s1s2A translation matrix T with the first vision measuring unit (3) and the second vision measuring unit (4)s1s2。
4. The visual measurement method for the coaxiality error of the double bearing holes according to claim 3, wherein the parameters of the large-field-of-view camera (11) and the PnP principle are used for respectively solving the parameters of each sub-target and the external parameters of the large-field-of-view camera (11).
5. The visual measurement method for the coaxiality error of the double bearing holes as claimed in claim 1, wherein for the deep bearing hole, the axis equation of the bearing hole is calculated by adopting a least square fitting method through collecting point cloud data of the cylindrical surface in the bearing hole.
6. The visual measurement method for the coaxiality error of the double bearing holes as claimed in claim 1, wherein the visual measurement method for the coaxiality error of the double bearing holes is suitable for a Visio Studio or Matlab platform.
7. The visual measurement method for the coaxiality error of the double bearing holes as claimed in claim 1, wherein the obtained coaxiality error evaluation parameters of the double bearing holes comprise the spatial distance and the included angle of the two axes.
8. A double-bearing hole coaxiality error visual measurement device is characterized by comprising a first visual measurement unit (3), a second visual measurement unit (4), a calibration unit and a data processing unit;
the first vision measuring unit (3) is used for acquiring end surface point cloud data of the first bearing hole (1);
the second vision measuring unit (4) is used for acquiring end surface point cloud data of the second bearing hole (2);
the calibration unit is used for calibrating the relative position relation of the first vision measurement unit (3) and the second vision measurement unit (4);
the data processing unit is used for processing the obtained relative position relation and the end face point cloud data to obtain the coaxiality error evaluation parameters of the double-bearing hole.
9. A visual double-bearing-hole coaxiality error measuring device according to claim 8, wherein the first visual measuring unit (3) and the second visual measuring unit (4) employ structured light visual measuring units.
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