CN108534679B - A kind of cylindrical member axis pose without target self-operated measuring unit and method - Google Patents

A kind of cylindrical member axis pose without target self-operated measuring unit and method Download PDF

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CN108534679B
CN108534679B CN201810456088.6A CN201810456088A CN108534679B CN 108534679 B CN108534679 B CN 108534679B CN 201810456088 A CN201810456088 A CN 201810456088A CN 108534679 B CN108534679 B CN 108534679B
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cylindrical
axis
coordinate
profile
point
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CN108534679A (en
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仇原鹰
张解语
芦顺利
段学超
盛英
赵泽
宁博
程培涛
米建伟
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Xidian Univ
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Xidian Univ
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical means
    • G01B11/002Measuring arrangements characterised by the use of optical means for measuring two or more coordinates

Abstract

The invention proposes a kind of cylindrical member axis poses without target self-operated measuring unit and method, it is intended to meet automation, it is non-contact and without target under the premise of, improve cylindrical member pose measurement precision.Realize step are as follows: establish measurement coordinate system around measuring device;Control computer obtained by laser profile sensor be located at it is several it is parallel it is unilateral on cylindrical member cross section profile;Control computer calculates separately the match point of cylindrical member axis and the match point of bus on each section;Control pitch angle and deflection angle that computer calculates cylindrical member axis;The synthesis match point that computer calculates cylindrical member axis is controlled, these synthesis match points carry out space line fitting, obtain the pose parameter of cylindrical member axis.The present invention can be used for the accurate measurement of cylindrical member axis pose during cylindrical member Automated assembly, so that pose adjustment mechanism is adjusted.

Description

A kind of cylindrical member axis pose without target self-operated measuring unit and method
Technical field
The invention belongs to Technology of Precision Measurement fields, are related to a kind of device for cylindrical member axis pose automatic measurement And method, it can be used in production process carrying out automatic measurement to cylindrical member pose.
Background technique
Cylindrical member is one of part most basic in industrial production, and to spacecraft, the processes such as pipeline welding are carried out When automatic updating, the pose for accurately, automatically measuring cylindrical member axis is generally required, and be adjusted to it.Due to the survey Accuracy of measurement will directly affect the precision of following process, therefore have higher requirement to the measure of precision of measurement process.Meanwhile being The demand of the following unmanned factory is coped with, new measuring technique should get rid of the dependence to a line operator, and complete independently is to quilt The measurement of object is surveyed, the efficiency of production assembly is improved.
To meet the needs of industrial automation, assembly efficiency is improved, needs control system before not needing human assistance Put pose that is automatic, critically measuring cylindrical member.Therefore, measuring device should be met the following requirements: one, being measured to meet The basic demand of automation, measurement process should be automatically performed, and the use of measurement target drone should be avoided, with anti-fouling measured object table Face and increase human cost;It two, is to ensure that assembling quality, measurement method should precision with higher;Three, in view of industrial ring Various interference present in border, measurement method should have strong anti-interference ability.
The country has some mechanisms to be related to the measurement problem of cylindrical member axis pose at present, meets to a certain extent State three point requirements.Such as BJ University of Aeronautics & Astronautics's literal arts was published in " CIM Technology " the 22nd in 2016 at it It rolls up and refers to one kind in the 3rd 686-694 pages of the phase of paper " large scale Products Digital intelligently docking key technology research " and be based on The large scale product docking system of laser tracker.Within the system, tested part table is attached to by laser tracker measurement The target ball position in face, to solve the spatial pose of tested part.It does not need manually to participate in this method measurement process, from certain The demand of automation pose measurement is met in degree, but needs corresponding measurement target ball manually installed to each tested part, The demand of automatic measurement cannot be fully met.And such method is practical that obtain is position of the target ball relative to measuring instrument, If there are errors for the installation of target ball position, measurement error not can avoid still.Jin Herong etc. was published in " China's machinery in 2017 at it Engineering " in 88-92 pages of the phase of volume 28 the 1st of paper " bay section automatic assembling pose Research of Solving Method ", using binocular vision pair The tested several index point positions in bay section surface measure, to solve the spatial pose of measured object.This method is to a certain degree On solve the problems, such as installation target ball, but still need to spray corresponding index point on tested part surface.In order to avoid measurement The introducing of target or target ball, it is entitled " for measuring the column with round cambered surface such as Publication No. CN 106197266A The Chinese patent application of the method for the pose of body " discloses a kind of method for measuring the pose of columnar object.This method In, real-time measurement is carried out by outline data of the linear laser two-dimensional measurement sensor to measured object section, and to the number of acquisition Strong point is screened, and is excluded the measurement data for being not belonging to elliptic arc, is then fitted to elliptic arc, and elliptical feature ginseng is obtained Number, then space calculation processing is carried out to parameter, obtain the posture information of cylindrical body.But this method is laid particular emphasis on is to acquisition data point The no screening for belonging to elliptic contour is fitted to obtain the elliptical geometric parameter in section by part elliptical, and according to axis pose and Mapping relations between the ellipse of section solve the pose of measured object axis.In this method, it cannot exclude due to sensor accuracy, vibration The problems such as dynamic, is interfered caused by measurement result, herein under the premise of, for imperfect elliptic arc of the central angle less than 180 °, Lesser measurement noise can cause fitting result wider margin of variation, therefore estimate quilt by the geometric parameter in a section The method precision for surveying cylindrical profile axis is lower, and there may be more Xie Wenti since projection relation is uncertain.
Summary of the invention
It is an object of the invention to overcome above-mentioned the shortcomings of the prior art, a kind of nothing of cylindrical member axis pose is proposed Target self-operated measuring unit and method, for improving measurement accuracy while guaranteeing the degree of automation.
A kind of cylindrical member axis pose without target self-operated measuring unit, including pedestal 1, support unit 2, measuring unit 3 With control computer 4;
The support unit 2, the support pallet 22 including supporting guide 21 and erection on it, the supporting guide 21 Including two closed slides, pedestal 1 is fixed on by mounting base, described mounting base one end is located at the position between two closed slides It sets and is fixed with transfer motor 24, the transfer motor 24 is by transfer lead screw 23 connected to it, and driving support pallet 22 is along support The length direction of guide rail 21 is mobile;
The measuring unit 3, including straight line mould group 32, driving motor 33, encoder 34, support slipper 35 and cable support 36;The straight line mould group 32 is fixed on pedestal 1, and the length direction of its guide rail is parallel with the guide rail on supporting guide 21;Institute State the tail portion that encoder 34 is connected to driving motor 33;The driving motor 33 passes through the input shaft of shaft coupling and straight line mould group 32 Connection;Laser profile sensor 31 is fixed on the support slipper 35, lower end and straight line mould group 32 connect;The cable support 36 are fixed on pedestal 1 by two support rods 37, are used to support the drag chain connecting with laser profile sensor 31;The driving Motor 33 is translated by support slipper 35, driving laser profile sensor 31 along the guide rail of straight line mould group 32;
The control computer 4, is handled, together for the measurement data to laser profile sensor 31, encoder 34 When transfer motor 24 and driving motor 33 are controlled.
Preferably, the straight line mould group 32, running part is using lead screw or synchronous band structure.
Preferably, the support slipper 35, including mould group sliding block 351 and the biography being vertically fixed on mould group sliding block 351 Sensor support plate 352;352 one side of the board of sensor support plate is fixed, and there are two limit 31 height of laser profile sensor Limited block 354, the other side are fixed with counterweight 353;352 lower surface of sensor support plate is connected with mould group sliding block 351.
A kind of cylindrical member axis pose without target method for automatic measurement, comprising the following steps:
(1) measurement coordinate system is established:
It is measurement origin O with one end of straight line mould group, using the direction of travel of support slipper as X-axis, laser profile sensor Depth of field direction be Y-axis, visual field width direction be Z axis, establish measurement coordinate system O-XYZ;
(2) control computer obtains the cross section profile L of cylindrical memberi:
(2a) laser profile sensor is scanned the side of cylindrical member along the X-direction of measurement coordinate system O-XYZ, and Obtained scanning element cloud is uploaded to control computer, while the X axis coordinate of each scanning element of record is uploaded to control by encoder Computer processed;
(2b) controls computer by the N number of point chosen between the maxima and minima of scanning element cloud X axis coordinate, builds The vertical N number of section parallel with plane YOZ, and using the intersection of each section and scanning element cloud as cross section profile, obtain cylindrical member N number of cross section profile Li, wherein i is the serial number of cross section profile, and i=1,2 ..., N, N is the sum of cross section profile;
(3) control computer calculates the match point C of cylindrical member axisiWith the match point P of busi:
(3a) controls computer to each cross section profile LiOval least square fitting is carried out in its affiliated plane, is obtained N number of ellipse;
(3b) is to each elliptical center of circle (yCi,zCi) X-coordinate of adding section where it, obtaining N number of coordinate is (xi, yCi,zCi) spatial point, and as the match point C of cylindrical member axisi;Wherein xiIt is sat for the X in section where the oval center of circle Mark, yCi, zCiThe Y-coordinate and Z coordinate in the respectively oval center of circle;
(3c) controls computer in N number of cross section profile LiIt is upper to extract maximum Y-coordinate y respectivelyPi, and find out each maximum Y and sit Mark yPiN number of X-coordinate x of corresponding pointsiAnd Z coordinate zPi, obtaining N number of coordinate is (xi,yPi,zPi) spatial point, as bus Match point Pi;Wherein, xiFor PiThe X-coordinate in place section, yPi、zPiRespectively PiY-coordinate and Z coordinate;
(4) control computer calculates the pitch angle and deflection angle of cylindrical member axis:
(4a) controls computer to the match point C of N number of cylindrical member axisiIt is straight that subpoint on plane XOZ carries out plane Line fitting, and using the angle of obtained fitting a straight line and X-axis forward direction as the pitch angle γ of cylindrical member axis;
(4b) controls computer to the match point P of N number of cylindrical member busiIt is straight that subpoint on plane XOY carries out plane Line fitting, and using the angle of obtained fitting a straight line and X-axis forward direction as the deflection angle β of cylindrical member axis;
(5) control computer obtains the synthesis match point of cylindrical member axis:
(5a) controls computer according to pitch angle γ, deflection angle β and cylindrical member radius R, calculates cylindrical member cross section profile Li Correspond to the long a of elliptical theoretical major semiaxis and rotation angle θ;
(5b) controls computer and calculates Y-axis theory offset Δ y of the cylindrical member bus relative to axis:
Wherein, t is coefficient,
(5c) controls computer for N number of cylindrical member bus match point PiAlong Y-axis translation-Δ y, the Y after obtaining N number of translation is sat Mark yCAi, and will be with xiFor X-coordinate, yCAiFor Y-coordinate, zCiFor Z coordinate creation N number of three-dimensional space point, as cylindrical member axis N number of comprehensive match point Si
(6) pose parameter of cylindrical member axis is calculated:
Computer is controlled to N number of comprehensive match point SiSpace line fitting is carried out, cylindrical member axis and plane YOZ's are obtained Point of intersection S0(0,y0,z0) and indicate the direction vector T of cylindrical member axis direction, and by S0(0,y0,z0) and T as cylindrical member axis The pose parameter of line.
Compared with the prior art, the invention has the following advantages:
1. the present invention is scanned tested cylindrical member side along track by laser profile sensor, cylindrical member side is obtained The point cloud data in face obtains several elliptic contours, and pass through in such a way that several parallel cuts and the point cloud data seek common ground It is fitted and asks the mode of extreme value to acquire centerline fit point and bus match point on each section, and then synthesized comprehensive Match point is closed, by obtaining cylindrical member pose to these synthesis match point application space straight line fittings.Pass through laser with existing Profile sensor obtains a profile and fitted ellipse on cylindrical member section, and estimates axis pose by elliptical geometric parameter Method compare, data redundancy is big, during avoiding imperfect ellipse fitting, due to factors such as sensor accuracy, structures Imperfect ellipse fitting error caused by measurement noise is introduced, measurement accuracy is effectively increased.
2. the present invention drives laser profile sensor to be scanned tested cylindrical member by driving motor, and passes through control The point cloud data that computer disposal scanning obtains.Compared with the existing measurement method for needing installation or spraying target, measurement process In do not need manually to participate in, therefore avoid damage of the target to tested part surface, while for the biggish product of batch, Due to eliminating the process of target installation or spraying, production process is simplified, production efficiency is improved.
3. laser profile sensor is selected to be scanned tested part, measured object is clapped compared to using industrial camera According to measurement method, the anti-interference ability of laser is stronger, and stabilization of equipment performance is more preferable.
Detailed description of the invention
Fig. 1 is the overall structure diagram of measuring device of the present invention;
Fig. 2 is the structural schematic diagram of support slipper of the present invention;
Fig. 3 is the schematic illustration of measurement method of the present invention;
Fig. 4 is the implementation process block diagram of measurement method of the present invention;
Fig. 5 is the deflection angle of ellipse and cylindrical member axis that section of the present invention and cylindrical member external cylindrical surface are crossed to form, bows The schematic diagram of relationship between the elevation angle.
Specific embodiment
In the following with reference to the drawings and specific embodiments, present invention is further described in detail:
Referring to Fig.1, a kind of cylindrical member axis pose without target self-operated measuring unit, including pedestal 1, support unit 2 is surveyed Measure unit 3 and control computer 4.
Wherein, support unit 2 includes supporting guide 21, supports pallet 22, transfer lead screw 23, transfer motor 24.Support is led 21 upper surface two sides of rail are equipped with two closed slides, and lower part is fixed on pedestal 1 by mounting base.Support 22 lower surface of pallet logical It crosses guide rail slide block to be erected on supporting guide 21, upper surface is placed with tested cylindrical member, allows cylindrical member along support Guide rail 21 slides.A transfer lead screw 23, the axis of the lead screw and the central axes side of supporting guide 21 are equipped with inside supporting guide To parallel, support pallet is connect by the nut of its bottom with transfer lead screw 23.Transfer lead screw 23 and it is fixed on supporting guide 21 On transfer motor 24 connect, by the rotation of transfer motor 24, support pallet 22 to be driven and moved along supporting guide 21, will Its cylindrical member lifted moves in measurement position.
Measuring unit 3 includes straight line mould group 32, support slipper 35 and cable support 36.Wherein, straight line mould group 32 is one Kind linear transmission, is mainly made of drive mechanism and mould group sliding rail two parts, sliding for converting mould group for rotary motion The linear motion of block, according to the difference of its drive mechanism, straight line mould group can be divided into two class of screw type or synchronous belt type.The straight line mould The mould group sliding rail of group 32 is parallel to supporting guide 21, and underrun bolt is connect with pedestal 1.32 one end of straight line mould group is equipped with drive Dynamic motor 33, the driving motor tail end are connected with encoder 34.
Referring to Fig. 2, the support slipper 35 includes mould group sliding block 351, sensor support plate 352, counterweight 353 and limited block 354, wherein mould group sliding block 351 is mounted on 352 lower surface of sensor support plate.Meanwhile mould group sliding block 351 is mounted on straight line mould On the mould group sliding rail of group 32, and it is connect with the drive mechanism of straight line mould group 32.With this configuration, driving motor 33 can drive biography Sensor support plate 352 is moved along the mould group sliding rail of straight line mould group 32, while being controlled computer and can be remembered in real time by encoder 34 Record the position of mould group sliding block 352.Two limited blocks 354 are mounted on plane of the sensor support plate 352 towards 2 side of support unit Different height on, limited for the installation site to laser profile sensor 31.Laser profile sensor 31 again can quilt Referred to as laser two-dimensional sensor, two-dimensional laser distance measuring sensor can project beam of laser band to measured object surface, and measure The spatial position of each point on the laser rays, in the present embodiment, laser profile sensor levels be installed on two limited blocks 354 it Between, and guarantee plane and 1 upper surface of pedestal determined by the laser emitter of laser rays and laser profile sensor that it is projected Vertically.Installation site for the measurement demand for adapting to different-diameter cylindrical member, laser profile sensor 31 can be limited at two It is vertically adjusted between block 34.
The cable support 36 is fixed on pedestal 1 by two support rods 37, is located at 31 lower section of laser profile sensor, Its inner containment has drag chain, and one end and cable support 36 connect, and the other end and laser profile sensor 31 connect, to this The cable of laser profile sensor is protected.And the cable support 36 can be moved up and down along two support rods 37, to adapt to The different height of laser profile sensor 31.
The control computer 4 is used to realize measuring system and control, i.e., to laser profile sensor 31, encoder 34 Measurement data is handled, and control transfer motor 24, driving motor 33 are mobile.
With reference to Fig. 3, measuring principle of the present invention are as follows:
Laser profile sensor 31 is scanned tested cylindrical member side along X-axis, obtains and is located on several parallel planes Cross section profile Li, it is part elliptical arc according to the space geometry profile, therefore can into ellipse fitting to each contour line Obtain one group of ellipse fitting center of circle Ci, space line fitting is carried out to these centers of circle, the pose of cylindrical member axis can be obtained;Simultaneously every A contour line LiIt is upper to extract the point P with maximum Y-coordinatei, progress space line is put to these and is fitted to obtain the Yi Tiaote of cylindrical member Different bus, the special bus are parallel with cylindrical member axis.But in above-mentioned point, CiPoor, the P along Y-axis precisioniIt is poor along Z axis precision, Therefore to PiY-coordinate translated, enable its replace CiY-coordinate, obtain comprehensive match point.Space is carried out to comprehensive match point Straight line fitting can accurately measure the axis pose of cylindrical member.
Referring to Fig. 4, a kind of cylindrical member axis pose without target automated process, include the following steps:
Step 1) establishes three-dimensional measurement coordinate system: being measurement origin O with one end of straight line mould group 32, with support slipper 35 Direction of travel is X-axis, and the depth of field direction of laser profile sensor 31 is Y-axis, and visual field width direction is Z axis, establishes such as Fig. 4 Shown in measurement coordinate system O-XYZ.
When describing one with the pose of the plane YOZ space line intersected, can by pitch angle γ, deflection angle β and Its spatial pose is completely determined with the intersection point of plane YOZ.Wherein pitch angle γ be defined as projection of the straight line on plane XOZ and The angle of X-axis forward direction, deflection angle β are defined as the angle of projection and X-axis forward direction of the straight line on plane XOY.
Step 2) controls the cross section profile L that computer 4 obtains cylindrical memberi:
Step 2a) under the driving of control computer 4, X of the laser profile sensor 31 along above-mentioned measurement coordinate system O-XYZ Axis direction is scanned the side of cylindrical member, and obtained scanning element cloud is uploaded to control computer 4, while encoder 34 The X axis coordinate of each scanning element recorded in real time is uploaded to control computer.
Wherein, scanning element cloud refers in coordinate system O-XYZ, is measured by laser profile sensor, on cylindrical member side The Y-coordinate and Z coordinate of several discrete points of even distribution, and the X-coordinate of these points measured by encoder.
Step 2b) control computer 4 it is N number of by what is chosen between the maxima and minima of scanning element cloud X axis coordinate Point establishes the N number of section parallel with plane YOZ, and using the intersection of each section and scanning element cloud as cross section profile, obtains cylinder N number of cross section profile L of shape parti, wherein i is the serial number of cross section profile, and i=1,2 ..., N, N is cross section profile LiSum;
Step 3) controls the match point C that computer calculates cylindrical member axisiWith the match point P of busi:
Step 3a) according to space geometry it is found that the intersection of above-mentioned section and cylindrical member external cylindrical surface should be an ellipse, because This, each cross section profile LiIt should belong to the same ellipse.Computer is controlled to each cross section profile LiIt is carried out in its affiliated plane Oval least square fitting, available N number of ellipse, i.e. long and short half axial length of this N number of elliptical major semiaxis, the oval center of circle position Set (yCi,zCi) and elliptical rotation angle.
Step 3b) it is only capable of obtaining the Y-coordinate and Z coordinate in N number of oval center of circle by above step, therefore need to be to each ellipse The center of circle (yCi,zCi) X-coordinate of adding section where it, obtaining N number of coordinate is (xi,yCi,zCi) spatial point.Wherein xiFor The X-coordinate in section, y where the oval center of circleCi, zCiThe Y-coordinate and Z coordinate in the respectively oval center of circle.By space geometry it is found that this A little points should theoretically be located on the axis of cylindrical member, and space line fitting is carried out to it, can obtain the axis of cylindrical member, therefore claim These points are the match point C of cylindrical member axisi
Due to the factors such as the error of measuring instrument and environmental disturbances, measurement gained cross section profile LiUpper each point is by noise It influences, therefore be fitted the oval center of circle of gained to generate certain error.It can not in view of passing through separate unit laser profile sensor Tested cylindrical member, therefore cross section profile L is completely coverediFor incomplete oval data.Noise to may cause measure it is elliptical The center of circle is poor along sensor field of view depth direction precision.In coordinate system O-XYZ, which will lead to the deflection angle of fitting axis The Y-coordinate precision of β and axis and plane YOZ intersection point reduces.
Step 3c) to solve the above problems, control computer controls computer in N number of cross section profile LiIt is upper to extract respectively most Big Y-coordinate yPi, and find out N number of X-coordinate x of corresponding pointsiWith Z coordinate zPi, so that obtaining N number of coordinate is (xi,yPi,zPi) Spatial point.According to space geometry it is found that this N number of spatial point should be located on the same bus of cylindrical member, this N number of space is clicked through The fitting of row space line, can obtain a special bus of cylindrical member, therefore this N number of spatial point is referred to as the match point P of busi。 Wherein xiFor PiThe X-coordinate in place section, yPi、zPiRespectively PiY-coordinate and Z coordinate.
In the step, PiThe tangent line that point place belongs to elliptic contour is close vertical, therefore works as PiWhen affected by noise, along Z axis There to be biggish error, so as to cause the measurement error of fitting bus pitch angle.
In summary, in coordinate system O-XYZ, the match point C of axisiIt is higher along Z axis measurement accuracy, essence is measured along Y-axis It spends lower;The match point P of busiIt is higher along Y-axis measurement accuracy, along Z axis low measurement accuracy.
Step 4) controls the pitch angle and deflection angle that computer calculates cylindrical member axis:
If to the match point C of above-mentioned axisiWith the match point P of busiSpace line fitting, fitting gained axis are carried out respectively The pitch angle γ precision of line is preferably but deflection angle β precision is poor;Fitting gained bus deflection angle β precision is preferably but pitch angle γ is smart It spends poor.Therefore following steps are executed, with the higher attitude angle of extraction accuracy.
Step 4a) computer is controlled to the match point C of N number of cylindrical member axisiSubpoint on plane XOZ carries out plane Straight line fitting, and using the angle of obtained fitting a straight line and X-axis forward direction as the pitch angle γ of cylindrical member axis;
Step 4b) since cylindrical member bus is parallel to axis, computer is controlled to the match point P of N number of cylindrical member busi? Subpoint on plane XOY carries out plane and straight line fitting, and using the angle of obtained fitting a straight line and X-axis forward direction as cylindrical member The deflection angle β of axis;
Step 5) controls the synthesis match point that computer obtains cylindrical member axis:
According to space geometry it is found that in known cylindrical member deflection angle β, under the premise of the pitch angle γ of axis, bus fitting Point PiRelative to its corresponding centerline fit point CiPositional relationship be determining.Under the premise of not considering to measure noise, bus Match point PiWith centerline fit point CiPositional relationship can be found out by following process:
Step 5a) Fig. 5 is referred to, control computer calculates cylinder according to pitch angle elevation angle gamma, deflection angle β and cylindrical member radius R Shape part calculates cylindrical member cross section profile LiThe long a of corresponding elliptical theoretical major semiaxis:
Wherein, MN is one section of cylindrical member axis, and MA was the point M straight line parallel with X-axis, and NA is perpendicular to MA.Cross MA work Plane MAB is parallel with plane XOZ, and crossing MA, to make plane MAC parallel with plane XOY, and wherein NB is perpendicular to plane MAB, NC perpendicular to Plane MAC.The intersection of then ∠ BMA=γ, ∠ CMA=β, plane NAB and cylindrical member external cylindrical surface is cross section profile LiIt is corresponding Ellipse, the long radius for being equal to tested cylindrical member external cylindrical surface of the elliptical semi-minor axis.Enable MA=1, extend NA hand over external cylindrical surface in D' crosses D' as D'D and is parallel to MN, enables ND perpendicular to D'D, according to perspective relation, cross section profile LiCorresponding elliptical major semiaxis with ND' is overlapped.ND is cylindrical member radius, ND=R.Meanwhile MN is vertical with ND, then ∠ DND'=∠ NMA.Therefore, cross section profile Li The corresponding elliptical long a of major semiaxis are as follows:
A=ND'=ND/cos ∠ DND'=R/cos ∠ NMA (1)
Wherein,Then:
Due to NA and cross section profile LiCorresponding elliptical long overlapping of axles, the angle of Y-axis is corresponding elliptical rotation angle θ, To avoid ambiguity, defining ELLIPTIC REVOLUTION angle θ is that Y-axis forward direction edge rotates counterclockwise to the rotation angle parallel with oval major semiaxis, θ is the angle of directed line segment NA and Y-axis forward direction known to then, is had:
(5b) all cross section profile LiCorresponding elliptical shape can be indicated by following equation:
The ellipse center of circle is overlapped with coordinate origin.Due to bus match point PiSlope is infinite at theoretical present position Greatly, therefore to formula (4) are with respect to y derivation and to take denominator be zero, it is as follows to obtain equation:
Wherein, coefficient t is the ratio of y and z.
(5) are substituted into (4), are solved:
Z=ty (7)
According to perspective relation it is found that the long satisfaction of above-mentioned elliptical semi-minor axis:
B=R (8)
The radius of cylindrical member generally can all be obtained ahead of time in batch assembly, can be to N number of elliptic contour L if can not obtaini It is fitted and takes the average value of its semi-minor axis length as cylindrical member radius R.
(8) are substituted into (6) and (7), it is known that bus match point PiRelative axis match point CiTranslational movement Δ y and Δ z meet Three formula below, it may be assumed that
Δ z=t Δ y (11)
(5c) is according to aforementioned it is found that the centerline fit point C obtained by measurementiY-coordinate precision it is poor, bus match point PiZ coordinate precision it is poor, therefore can be by N number of bus match point PiY-coordinate along Y-axis translation-Δ y, after obtaining N number of translation yCAi
In this way, taking N number of centerline fit point CiZ coordinate zCi, the Y-coordinate y that is put after N number of translationCAiAnd the X of corresponding flat Coordinate xi, establishing N number of coordinate is (xi,yCAi,zCi) three-dimensional space point, and be denoted as comprehensive match point Si
(6) pose parameter of cylindrical member axis is calculated:
Computer is controlled to N number of comprehensive match point SiSpace line fitting is carried out, cylindrical member axis and plane YOZ's are obtained Point of intersection S0(0,y0,z0) and indicate the direction vector T of cylindrical member axis direction, and by S0(0,y0,z0) and T as cylindrical member axis The pose parameter of line so far can accurately acquire the pose parameter of cylindrical member axis.
Above description and examples, preferred embodiment only of the invention, do not constitute any limitation of the invention, it is clear that right For one of skill in the art, after understanding the content of present invention and design principle, may all it be based on the principle of the present invention In the case where structure, carry out in form and the various modifications and variations in details, but these repairing based on inventive concept Just with change still within scope of protection of the claims of the invention.

Claims (2)

1. a kind of cylindrical member axis pose without target method for automatic measurement, which is characterized in that by cylindrical member pose without target It marks self-operated measuring unit to realize, which includes pedestal (1), support unit (2), measuring unit (3) and control computer (4);
Support unit (2) is fixed on pedestal (1), is used to support tested cylindrical member, and measuring unit (3) is parallel to support unit (2) it is fixed on pedestal (1);
Wherein, the measuring unit (3), including straight line mould group (32), driving motor (33), encoder (34), support slipper (35) and cable support (36);The straight line mould group (32) is fixed on pedestal (1), and the length direction of its guide rail is led with support Guide rail on rail (21) is parallel;The encoder (34) is connected to the tail portion of driving motor (33);The driving motor (33) is logical Cross the input axis connection of shaft coupling Yu straight line mould group (32);Laser profile sensor is fixed on the support slipper (35) (31), lower end and straight line mould group (32) connection;The cable support (36) is fixed on pedestal (1) by two support rods (37) On, it is used to support the drag chain connecting with laser profile sensor (31);The driving motor (33) is driven by support slipper (35) Dynamic laser profile sensor (31) are translated along the guide rail of straight line mould group (32);
Measurement method the following steps are included:
(1) measurement coordinate system is established:
It is measurement origin O with one end of straight line mould group, using the direction of travel of support slipper as X-axis, the view of laser profile sensor Depth of field direction is Y-axis, and visual field width direction is Z axis, establishes measurement coordinate system O-XYZ;
(2) control computer obtains the cross section profile L of cylindrical memberi:
(2a) laser profile sensor is scanned the side of cylindrical member along the X-direction of measurement coordinate system O-XYZ, and will To scanning element cloud be uploaded to control computer, while the X axis coordinate of each scanning element of record is uploaded to control meter by encoder Calculation machine;
(2b) controls computer by N number of point for choosing between the maxima and minima of scanning element cloud X axis coordinate, establish with Plane YOZ parallel N number of section, and using the intersection of each section and scanning element cloud as cross section profile, obtain the N number of of cylindrical member Cross section profile Li, wherein i is the serial number of cross section profile, and i=1,2 ..., N, N is the sum of cross section profile;
(3) control computer calculates the match point C of cylindrical member axisiWith the match point P of busi:
(3a) controls computer to each cross section profile LiOval least square fitting is carried out in its affiliated plane, is obtained N number of ellipse Circle;
(3b) is to each elliptical center of circle (yCi,zCi) X-coordinate of adding section where it, obtaining N number of coordinate is (xi,yCi,zCi) Spatial point, and as the match point C of cylindrical member axisi;Wherein xiFor the X-coordinate in section where the oval center of circle, yCi, zCi The Y-coordinate and Z coordinate in the respectively oval center of circle;
(3c) controls computer in N number of cross section profile LiIt is upper to extract maximum Y-coordinate y respectivelyPi, and find out each maximum Y-coordinate yPi N number of X-coordinate x of corresponding pointsiAnd Z coordinate zPi, obtaining N number of coordinate is (xi,yPi,zPi) spatial point, the fitting as bus Point .Pi.;Wherein, xiFor PiThe X-coordinate in place section, yPi、zPiRespectively PiY-coordinate and Z coordinate;
(4) control computer calculates the pitch angle and deflection angle of cylindrical member axis:
(4a) controls computer to the match point C of N number of cylindrical member axisiIt is quasi- that subpoint on plane XOZ carries out plane and straight line It closes, and using the angle of obtained fitting a straight line and X-axis forward direction as the pitch angle γ of cylindrical member axis;
(4b) controls computer to the match point P of N number of cylindrical member busiIt is quasi- that subpoint on plane XOY carries out plane and straight line It closes, and using the angle of obtained fitting a straight line and X-axis forward direction as the deflection angle β of cylindrical member axis;
(5) control computer obtains the synthesis match point of cylindrical member axis:
(5a) controls computer according to pitch angle γ, deflection angle β and cylindrical member radius R, calculates cylindrical member cross section profile LiCorrespondence is ellipse The round long a of theoretical major semiaxis and rotation angle θ;
(5b) controls computer and calculates Y-axis theory offset Δ y of the cylindrical member bus relative to axis:
Wherein, t is coefficient,
(5c) controls computer for N number of cylindrical member bus match point PiY-coordinate along Y-axis translation-Δ y, after obtaining N number of translation yCAi, and will be with xiFor X-coordinate, yCAiFor Y-coordinate, zCiFor N number of three-dimensional space point of Z coordinate creation, N as cylindrical member axis A comprehensive match point Si
(6) pose parameter of cylindrical member axis is calculated:
Computer is controlled to N number of comprehensive match point SiSpace line fitting is carried out, the intersection point of cylindrical member axis Yu plane YOZ is obtained S0(0,y0,z0) and indicate the direction vector T of cylindrical member axis direction, and by S0(0,y0,z0) and T as cylindrical member axis Pose parameter.
2. a kind of cylindrical member axis pose according to claim 1 without target method for automatic measurement, which is characterized in that step Suddenly the L of calculating cylindrical member cross section profile described in (5a)iCorrespond to the long a of elliptical theoretical major semiaxis and rotation angle θ, calculation formula point Not are as follows:
Wherein, β is the deflection angle of cylindrical member, and γ is the pitch angle of cylindrical member, and R is the radius of cylindrical member.
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