CN109613519B - Involution attitude adjusting method based on multi-laser tracker measuring field - Google Patents
Involution attitude adjusting method based on multi-laser tracker measuring field Download PDFInfo
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Abstract
The invention provides a involution attitude adjusting method based on a measuring field of a multi-laser tracker, which comprises the following steps: s1, establishing an ideal assembling body model; s2, constructing a multi-laser tracker measuring field; s3, iterative computation is carried out by adopting a beam adjustment method, and a homogeneous conversion matrix between any two laser trackers is solved; s4, calculating the coordinates of each measurement auxiliary point in the global coordinate system; and S5, assembling the target workpiece tool on the reference workpiece tool. The position selection of the measurement auxiliary points is less in restriction and more flexible, so that the relative position between the measurement auxiliary points is prevented from drifting, and the measurement precision is improved. The station transfer calculation adopts a beam adjustment method based on the global optimization idea, can complete the station transfer calculation among a plurality of laser trackers at one time, and improves the station transfer precision. Meanwhile, the attitude adjustment is guided by adopting the measured data of the laser tracker, the influence of the placement error of the target measuring point on the estimation result of the position of the target measuring point is reduced, and the measuring precision is improved.
Description
Technical Field
The invention relates to the technical field of digital measurement, in particular to a multi-laser-tracker-measurement-field-based involution attitude adjusting method.
Background
Because the parts of the wings, the fuselage and the like of the large-scale airplane often have the characteristics of large area, small rigidity, easy deformation and the like and the particularity of the working environment of the large-scale airplane, in the assembly process of the parts of the large-scale airplane, the auxiliary assembly needs to be carried out by means of a plurality of digital devices (such as various positioners, industrial robots and the like).
In order to ensure accurate relative position relationship among the digital devices, tools and components during the assembly process, a uniform measurement field needs to be established, and a uniform assembly coordinate system (i.e., a global coordinate system) needs to be established.
Establishing a uniform measurement field mainly relies on a wide range of high precision measurement equipment (such as laser trackers, iGPS, industrial cameras, etc.). The laser tracker has the characteristics of high precision, mobility, wide working range and the like, and is a commonly-used measuring instrument in aviation assembly tasks.
At present, the way of establishing a unified measurement field is: in the working space, a plurality of measurement auxiliary points (Enhanced Reference systems, ERS for short, also called Enhanced Reference systems) and a plurality of laser trackers are installed at stable positions (such as the ground or fixed tools, etc.), each laser tracker measuring a plurality of measurement auxiliary point positions, and the assembly coordinate System of the component to be assembled is determined by these measurement auxiliary points whose spatial positions are known. At this time, the coordinate values of the measurement auxiliary points in the assembly coordinate system may be considered as fixed, but the actual positions of the measurement auxiliary points may change due to factors such as temperature and gravity, so that the coordinate axis direction and unit length in the assembly coordinate system may change with time, and a large measurement error may exist in the constructed measurement field, thereby affecting the assembly quality of the large component.
After the assembly coordinate system is determined, in the process of transferring stations, an SVD algorithm or a Best-fit algorithm is generally adopted, the relative position and posture relationship between the measurement coordinate systems of two laser trackers can be determined each time, the relative relationship between the instruments with far distances can be determined after transferring stations for multiple times, and then data is unified under the assembly coordinate system, so that a large station transferring accumulated error is easily caused.
In the process of involution assembly of a target workpiece tool (provided with a target measuring point) and a reference workpiece tool (provided with a reference measuring point), the actual measurement positions of the target measuring point and the reference measuring point are measured firstly, then the measured data are weighted and averaged with the theoretical positions in an ideal model, then the poses of the target workpiece tool and the reference workpiece tool are fitted respectively, and the pose data are used for driving pose adjustment. However, the fitting measurement data has a large uncertainty due to installation errors and measurement errors, so that the fitted target workpiece tool and the fitted reference workpiece tool are prone to being inaccurate in pose, and therefore assembly quality is affected.
Disclosure of Invention
In view of the problems in the background art, an object of the present invention is to provide a method for adjusting the attitude of a multi-laser tracker measurement field, which has less restriction on the position selection of auxiliary measurement points, is more flexible, avoids the problem of drift of the relative positions of the auxiliary measurement points due to temperature, gravity, etc., and improves the measurement accuracy of the multi-laser tracker measurement field.
The invention also aims to provide a multi-laser-tracker-measurement-field-based involution attitude adjusting method, wherein the substation calculation adopts a beam adjustment method based on a global optimization idea, and can complete the substation calculation among a plurality of laser trackers at one time, so that the problem of error accumulation caused by only determining the poses between two laser trackers each time is solved, and the measurement precision of the multi-laser-tracker-measurement-field-based measurement field is improved.
The invention also aims to provide a involution attitude adjusting method based on a multi-laser tracker measuring field, which adopts the measured data of the laser tracker to guide attitude adjustment, avoids the process of fusing the measured data of a target measuring point on a target workpiece tool and the position of the target measuring point in an ideal digital model respectively and estimating the position of the target measuring point, reduces the influence of the placement error of the target measuring point on the estimation result of the position of the target measuring point and improves the measuring precision.
In order to achieve the above object, the present invention provides a method for adjusting the attitude based on the measurement fields of multiple laser trackers, which includes steps S1-S5.
And S1, respectively establishing three-dimensional models of the reference workpiece tool and the target workpiece tool in three-dimensional software and completing assembly to obtain an ideal assembly body model.
And S2, setting a plurality of laser trackers and a plurality of measurement auxiliary points in the actual working space to construct a multi-laser-tracker measurement field, wherein each laser tracker has a measurement coordinate system and at least measures the spatial positions of three measurement auxiliary points, each measurement auxiliary point is measured by at least two laser trackers, and the measurement coordinate system of one laser tracker is defined as a global coordinate system.
And S3, performing iterative calculation by adopting a beam adjustment method based on the measurement results of different laser trackers on the same measurement auxiliary point, and solving a homogeneous conversion matrix between any two laser trackers and the coordinates of each measurement auxiliary point in the global coordinate system.
And S4, calculating the coordinates of each measurement auxiliary point in the global coordinate system based on the measurement result of each measurement auxiliary point under the laser tracker participating in the measurement and the homogeneous conversion matrix between the laser tracker participating in the measurement and the corresponding laser tracker.
S5, in the multi-laser tracker measurement field, assembling a target workpiece fixture to a reference workpiece fixture, the reference workpiece fixture having a plurality of reference measurement points arranged thereon, the target workpiece fixture having a plurality of target measurement points arranged thereon, and S5 comprising the steps of:
s51, fixing a reference workpiece tool, and arranging a target workpiece tool and the reference workpiece tool oppositely, wherein the target workpiece tool is connected with automatic butt joint equipment;
s52, obtaining theoretical positions of the plurality of reference measuring points on the reference workpiece tool from an ideal assembly body model in three-dimensional software, wherein the number of the reference measuring points is g, and the number of the target measuring points is h
And theoretical positions of the target measurement points on the target workpiece tool
Wherein i represents the numbers of the plurality of reference measurement points, and j represents the numbers of the plurality of target measurement points;
s53, through the multiple laser trackers and the homogeneous conversion matrix among the multiple laser trackers
Obtaining the actual measurement positions of the plurality of reference measurement points on the reference workpiece tool under the global coordinate system
Actual measurement positions of the target measurement points on the target workpiece tool in the global coordinate system
S54, according to the actual measurement positions of the plurality of reference measurement points on the reference workpiece tool in the global coordinate system
Establishing a reference tool coordinate system of a reference workpiece tool and according to the actual measurement positions of the target measurement points on the target workpiece tool in the global coordinate system
Establishing a target tool coordinate system of a target workpiece tool;
s55, passing the measured positions of the plurality of reference measuring points
And theoretical position
Solving a homogeneous transformation matrix T between an actual reference workpiece tool and an ideal assembling body model in three-dimensional software1And is
S56, calculating a homogeneous transformation matrix T from an ideal assembling body model in three-dimensional software to an actual reference workpiece tool0And T0＝(T1)-1；
S57, passing the measured positions of the target measuring points
And theoretical position
Solving a homogeneous transformation matrix T between an actual target workpiece tool and an ideal assembling body model in three-dimensional software2And is
S58, calculating a homogeneous transformation matrix T of the target workpiece tool from the current actual measurement position to the ideal position3And T3＝T0·T2＝(T1)-1·T2And calculating the ideal positions of the target measuring points of the target workpiece tool in the ideal assembly state
S59, in the actual working space, the automatic butt joint equipment drives the target workpiece tool to complete homogeneous transformation of the matrix T3And the defined space rigid body moves so as to assemble the target workpiece tool to the reference workpiece tool.
The invention has the following beneficial effects:
the measurement auxiliary points have the functions of helping a plurality of laser trackers to determine the pose relationship among the measurement auxiliary points instead of forming the reference of a global coordinate system, so that the position selection of the measurement auxiliary points is less in restriction and more flexible, the problem that the relative positions among the measurement auxiliary points drift due to temperature, gravity and the like is solved, the measurement precision of a measurement field based on the multiple laser trackers is improved, and a complex compensation algorithm is avoided. Moreover, the substation calculation adopts a beam adjustment method based on the global optimization idea, and the substation calculation among a plurality of laser trackers can be completed at one time, so that the problem of error accumulation caused by only determining the pose between two laser trackers at each time is solved, and the substation precision in a measuring field of the plurality of laser trackers is improved. Meanwhile, the invention guides the posture adjustment by adopting the measured data of the laser tracker, avoids the process of respectively fusing the measured data of the target measuring point on the target workpiece tool and the position of the target measuring point in an ideal digital analog and estimating the position of the target measuring point, reduces the influence of the placement error of the target measuring point on the estimation result of the position of the target measuring point, and improves the measuring precision.
Drawings
FIG. 1 is a schematic diagram of a multi-laser-tracker measurement field established in the multi-laser-tracker-measurement-field-based involution pose alignment method of the present invention.
Fig. 2 is an ideal assembly model diagram after assembling the reference workpiece fixture 1 and the target workpiece fixture 2 built in the three-dimensional software.
Fig. 3 is a front view of fig. 2.
Fig. 4 is a schematic distribution diagram of the reference measurement points and the target measurement points before the reference workpiece fixture 1 and the target workpiece fixture 2 are assembled.
Wherein the reference numerals are as follows:
1 reference workpiece tool 21 target measuring point
11 reference measuring point M laser tracker
2 auxiliary point is measured to target work piece frock P
Detailed Description
The method for adjusting the attitude based on the multi-laser tracker measurement field according to the present invention will be described in detail with reference to the accompanying drawings.
Referring to fig. 1 to 4, the multi-laser tracker measurement field-based involution attitude adjustment method of the present invention includes steps S1, S2, S3, S4, and S5.
And S1, respectively establishing three-dimensional models of the reference workpiece tool 1 and the target workpiece tool 2 in three-dimensional software and completing assembly, thereby obtaining an ideal assembly body model (shown in figure 2).
S2, in the actual working space of the assembly site, a plurality of laser trackers M and a plurality of measurement auxiliary points P are set to construct a multi-laser-tracker measurement field (as shown in fig. 1). Each laser tracker M has its own measurement coordinate system (i.e., local coordinate system) and measures the spatial positions of at least three measurement auxiliary points P, and each measurement auxiliary point P is measured by at least two laser trackers M, so that a mesh-shaped graph connection relationship is formed between the plurality of laser trackers M and the plurality of measurement auxiliary points P. Also, the measurement coordinate system of one of the laser trackers M may be defined as a global coordinate system and denoted by O-XYZ, while the measurement coordinate system of the other laser tracker M may be denoted by O '-X' Y 'Z'.
And S3, performing iterative computation by adopting a beam adjustment method based on the measurement results of different laser trackers M on the same measurement auxiliary point P, and solving a homogeneous conversion matrix between any two laser trackers M (namely, the solving process of the homogeneous conversion matrix between any two laser trackers M is a transfer station computing process).
Here, based on steps S2 and S3, the measurement auxiliary point P no longer serves as a reference constituting the global coordinate system (i.e., the global coordinate system is not bound to the measurement auxiliary point P), but assists the plurality of laser trackers M in determining the pose relationship therebetween, so that the arrangement position of the measurement auxiliary point P does not need to be guaranteed not to change for a long time (i.e., does not need to be fixed to a specific position on the ground or a working platform), and only needs to be guaranteed to be visible by as many laser trackers M as possible at the same time and to be kept still during the stage of establishing the multi-laser-tracker measurement field. Therefore, the position selection of the measurement auxiliary points P is less restricted and more flexible, the problem that the relative position between the measurement auxiliary points P drifts due to the temperature, the gravity and the like is avoided, the measurement precision of the measurement field based on the multi-laser tracker is improved, and the complex compensation algorithm is avoided.
In addition, in step S3, since the substation calculation adopts the beam adjustment method based on the global optimization concept, it can complete the substation calculation between multiple laser trackers M at one time, thereby avoiding the error accumulation problem caused by determining the pose between two laser trackers M at each time, and improving the substation accuracy in the multi-laser-tracker measurement field.
In addition, compared with the traditional construction mode of the measuring field, the multi-laser tracker measuring field constructed by the invention expands the working range, improves the precision and the working flexibility, and can provide a set of systematic construction and working method for the measuring task under the relevant application scene.
The measurement auxiliary points P are a in number and the laser trackers M are b in number, and in step S3, steps S31, S32, S33, S34, S35, S36, and S37 may be included.
S31, the b-th laser tracker M and the a-th measurement auxiliary points P are respectively numbered, and the f-th (f is 1,2 … a) measurement auxiliary point P is measured by at least the M-th (M is 1,2 … b) laser tracker M and the n-th (n is 1,2 … b, n is not equal to M) laser tracker M.
S32, the actual measurement result P of the f-th auxiliary measurement point P under the measurement of the M-th laser tracker M and the n-th laser tracker Mfm＝(xfm,yfm,zfm)、Pfn＝(xfn,yfn,zfn) Are respectively converted into ball coordinate P'fm＝(rfm,αfm,βfm)、P'fn＝(rfn,αfn,βfn)。
S33, ranging error parameter u from laser tracker MrPitch angle error parameter uαAnd an azimuth error parameter uβConstructing a weight matrix
Wherein u isr、uαAnd uβCan be directly obtained through a product manual.
S34, setting the homogeneous conversion matrix between the mth laser tracker M and the nth laser tracker M as Tm nAnd said homogeneous transition matrix Tm nIncluding a transfer parameter RmnAnd tmnWherein R ismnIs a 3X 3 matrix and represents the amount of rotation t between the measurement coordinate system of the mth laser tracker M and the measurement coordinate system of the nth laser tracker MmnIs a 3 x 1 matrix and represents the translation amount between the measurement coordinate system of the mth laser tracker M and the measurement coordinate system of the nth laser tracker M, the homogeneous conversion matrix of all the laser trackers M is { T }m n}＝{T1 2,T1 3…T2 3,T2 4…T3 4… }, and { T }m nCorresponding transfer station parameter { R }mn}＝{R12,R13…R23,R24…R34…}、{tmn}＝{t12,t13…t23,t24…t34…}。
S35, estimating the estimation result of the f-th measurement auxiliary point P under the M-th laser tracker M according to the actual measurement result of the f-th measurement auxiliary point P under the n-th laser tracker M
S36, based on the Mahalanobis distance, constructing the reprojection error vector E (namely the target to be optimized) of all the measurement auxiliary points P, wherein the expression of E is as follows:
s37, using beam adjustment method to give RmnAnd tmnInitial value, continuously adjusting RmnAnd tmnUntil E obtains the minimum value, stopping iteration, wherein the station transfer parameter corresponding to the minimum value of E is the solved { R }mnAnd tmn}。
And S4, calculating the coordinates of each measurement auxiliary point P in the global coordinate system based on the measurement result of each measurement auxiliary point P under the laser tracker M participating in the measurement and the homogeneous conversion matrix between the laser tracker M participating in the measurement and the corresponding laser tracker M. Specifically, for each measurement assistance point P:
when the global coordinate system is the measurement coordinate system of the laser tracker M participating in measuring the measurement auxiliary point P, the coordinates of the measurement auxiliary point P in the global coordinate system are: measurement of the laser tracker M defined as a global coordinate system;
when the global coordinate system is the measurement coordinate system of the laser tracker M not participating in measuring the measurement auxiliary point P, the coordinates of the measurement auxiliary point P in the global coordinate system are: the measurement result of the laser tracker M involved in the measurement is directly multiplied by a homogeneous conversion matrix between the laser tracker M involved in the measurement and the laser tracker M defined as the global coordinate system (i.e. one-time transfer is performed to the global coordinate system); or, the measurement result of the laser tracker M involved in the measurement is multiplied by a homogeneous conversion matrix between the laser tracker M involved in the measurement and another laser tracker M, and then multiplied by a homogeneous conversion matrix between the another laser tracker M and the laser tracker M defined as a global coordinate system (i.e., twice rotating to be under the global coordinate system).
Of course, in some cases, the measurement result of the laser tracker M involved in the measurement may also be transferred to the global coordinate system by two or more times of transfer.
S5, in the multi-laser tracker measurement field, assembling the target workpiece 2 to the reference workpiece 1, the reference workpiece 1 having a plurality of reference measurement points 11 arranged thereon, the target workpiece 2 having a plurality of target measurement points 21 arranged thereon (as shown in fig. 4), and S5 including steps S51-S59.
And S51, fixing the reference workpiece tool 1, arranging the target workpiece tool 2 opposite to the reference workpiece tool 1, and connecting the target workpiece tool 2 with automatic butt joint equipment (not shown).
S52, obtaining theoretical positions of the plurality of reference measuring points 11 on the reference workpiece tool 1 from an ideal assembling body model in three-dimensional software, wherein the number of the reference measuring points 11 is g, and the number of the target measuring points 21 is h
And the theoretical positions of the target measurement points 21 on the target workpiece fixture 2
Where i denotes the number of the plurality of reference measurement points 11 and j denotes the number of the plurality of target measurement points 21.
S53, through the multiple laser trackers M and the homogeneous conversion matrix { T between the multiple laser trackers Mm nObtaining the actual measurement positions of the plurality of reference measurement points 11 on the reference workpiece fixture 1 under the global coordinate system
Actual measurement positions of the target measurement points 21 on the target workpiece fixture 2 in the global coordinate system
S54, according to the actual measurement positions of the plurality of reference measurement points 11 on the reference workpiece tool 1 in the global coordinate system
Establishing a reference tool coordinate system of the reference workpiece tool 1 and according to the actual measurement positions of the target measurement points 21 on the target workpiece tool 2 in the global coordinate system
And establishing a target tool coordinate system of the target workpiece tool 2.
In the assembling process, the relative pose between the reference tool coordinate system and the target tool coordinate system is used for representing the relative position between the reference workpiece tool 1 and the target workpiece tool 2. Here, since the reference tool coordinate system is established by the actual measurement data of the target measurement point 21, not only by the target measurement point 21 itself (the establishment of the target tool coordinate system is also similar), the coordinate system offset error caused by the deformation of the reference workpiece tool 1 and the target workpiece tool 2 due to the gravity is avoided, and the accuracy of the relative position between the reference workpiece tool 1 and the target workpiece tool 2 is ensured.
S55, passing through the measured positions of the plurality of reference measuring points 11
And theoretical position
Determining what is actualHomogeneous transformation matrix T between reference workpiece tool 1 and ideal assembling body model in three-dimensional software1And is
S56, calculating a homogeneous transformation matrix T from an ideal assembling body model in three-dimensional software to an actual reference workpiece tool 10And T0＝(T1)-1。
S57, passing through the measured positions of the target measuring points 21
And theoretical position
Solving a homogeneous transformation matrix T between an actual target workpiece tool 2 and an ideal assembling body model in three-dimensional software2And is
S58, calculating a homogeneous transformation matrix T between the current actual measurement position and the ideal position of the target workpiece tool 23And T3＝T0·T2＝(T1)-1·T2And calculating the ideal positions of the target measuring points 21 of the target workpiece tool 2 in the ideal assembling state
S59, in the actual working space, the automatic butt joint equipment drives the target workpiece tool 2 to complete the homogeneous transformation matrix T3The defined spatial rigid body moves to assemble the target workpiece fixture 2 to the reference workpiece fixture 1. In other words, during assembly, the target tool coordinate system of the target workpiece tool 2 is according to T3The defined spatial rigid body motion moves.
Based on the step S5, it can be seen that the method for adjusting the pose based on the multi-laser-tracker measuring field of the present invention adopts the measured data of the laser tracker M in the multi-laser-tracker measuring field to guide the pose adjustment, so as to avoid the processes of fusing the measured data of the target measuring point 21 on the target workpiece fixture 2 and the position thereof in the ideal digifax respectively and estimating the position of the target measuring point 21, reduce the influence of the placement error of the target measuring point 21 on the position estimation result of the target measuring point 21, and thereby improve the measurement accuracy.
Specifically, in step S59, the method may include the steps of: s591, in the three-dimensional software, determining the actual measurement positions of the plurality of reference measurement points 11 on the reference workpiece fixture 1 in the global coordinate system
Establishing a pre-assembly model of the reference workpiece tool 1, and passing the actual measurement positions of the target measurement points 21 on the target workpiece tool 2 under the global coordinate system
Establishing a preassembly model of the target workpiece tool 2, and transforming a matrix T by homogeneous times3Completing virtual preassembly by the defined space rigid body motion to obtain a virtual preassembly model; s592, finding out an interference region point { D ] on the pre-assembly model of the target workpiece tool 2 by comparing the virtual pre-assembly model with the ideal assembly model established in the step S1j}; s593, solving a homogeneous transformation matrix T from the ideal assembling body model to the actual target workpiece tool 24And T4＝(T2)-1Then interference region point { DjThe position of the interference area on the actual target workpiece tool 2 is
S594, processing an interference region on the actual target workpiece fixture 2 to prevent collision or clearance during actual assembly; s595, driving the target workpiece tool 2 to complete homogeneous transformation matrix T by the automatic docking equipment3The defined spatial rigid body moves to assemble the target workpiece fixture 2 to the reference workpiece fixture 1.
It should be noted that, if the processing precision of the target workpiece fixture 2 meets the assembly requirement, steps S591-S594 may be omitted, and step S595 may be directly executed.
The precision between the actual measurement position and the ideal actual measurement position of the target workpiece tool 2 is that, in order to improve the assembly precision between the target workpiece tool 2 and the reference workpiece tool 1, the multi-laser tracker M measurement field-based involution attitude adjusting method may further include the steps of:
s6, after the target workpiece fixture 2 is assembled to the reference workpiece fixture 1, obtaining the current actual measurement positions of the target measurement points 21 on the target workpiece fixture 2 in the global coordinate system by the plurality of laser trackers M
And calculating the current measured position
And the ideal position
Difference between them
S7，ERIf > S5-S6 are repeated until ERCompleting the assembly (namely, the target workpiece tool 2 is assembled to an ideal position);
S8，ERif so, the assembly is completed (i.e., the target workpiece fixture 2 is assembled to the desired position).
In step S55, the method specifically includes the following steps:
s551, providing
S552, the actual measurement position coordinate of any reference measurement point 11 is
And theoretical position coordinates of
Selecting at least four reference measuring points 11, and forming a plurality of groups of data by the actual measurement position coordinates and the theoretical position coordinates of the at least four reference measuring points 11, wherein any group of data satisfies the following equation set:
s553, all the equation sets formed by the multiple data sets are combined to calculate T1Of (2) is performed.
Similarly, in step S57, the following steps are included:
s571, setting
S572, the actual measurement position coordinates of the arbitrary target measurement point 21 are
And theoretical position coordinates of
Selecting at least four target measurement points 21, and forming a plurality of groups of data by the actual measurement position coordinates and the theoretical position coordinates of the at least four target measurement points 21, wherein any group of data satisfies the following equation set:
s573, simultaneously establishing all equation sets formed by the multiple groups of data to obtain T2Of (2) is performed.
In one embodiment, the involution attitude adjusting method based on the multi-laser tracker measuring field is applied to horizontal assembly of the wings of a large airplane, wherein a wing box framework of the wings is used as a reference workpiece tool 1, an upper skin and a shape-preserving tool thereof are used as a target workpiece tool 2, and automatic butt joint equipment connected with the target workpiece tool 2 is a parallel attitude adjusting mechanism consisting of 4 three-coordinate numerical control attitude adjusting positioning devices.
Before an upper skin and a conformal tool thereof are assembled on a wing box framework, firstly, arranging a reference measuring point (preferably, arranged at a pre-connecting hole on a wing rib and a wing spar) on the wing box framework, and installing a target measuring point (preferably, the target measuring point is arranged at a position on the upper skin and the conformal tool thereof, which has better rigidity, is close to the outer side and is easily measured by more laser trackers M); then, measuring the actual measurement positions of the M measurement reference measurement points and the target measurement points in the global coordinate system by adopting a plurality of laser trackers in a multi-laser-tracker measurement field; then, the homogeneous transformation matrix T between the current actual measurement position and the theoretical position of the target workpiece tool 2 is obtained through the method3。
In the specific assembling process, the wing box framework of the wing is kept fixed, and the upper skin and the shape-preserving tool thereof are driven by a parallel posture-adjusting mechanism consisting of 4 three-coordinate numerical control posture-adjusting positioning devices according to T3The defined space rigid body moves, so that the upper skin and the shape-preserving tool thereof can be accurately involuted to the wing box framework of the wing, and the upper skin and the shape-preserving tool thereof are aligned and jointed with the wing box framework of the wing.
Claims (8)
1. A involution attitude adjusting method based on a multi-laser tracker measuring field comprises the following steps:
s1, respectively establishing three-dimensional models of a reference workpiece tool (1) and a target workpiece tool (2) in three-dimensional software and completing assembly to obtain an ideal assembly body model;
s2, arranging a plurality of laser trackers (M) and a plurality of measurement auxiliary points (P) in an actual working space to construct a multi-laser-tracker measurement field, wherein each laser tracker (M) is provided with a measurement coordinate system and measures the spatial positions of at least three measurement auxiliary points (P), each measurement auxiliary point (P) is measured by at least two laser trackers (M), and the measurement coordinate system of one laser tracker (M) is defined as a global coordinate system;
s3, based on the measurement results of different laser trackers (M) to the same measurement auxiliary point (P), iterative computation is carried out by adopting a beam adjustment method, and a homogeneous conversion matrix between any two laser trackers (M) is solved;
s4, calculating the coordinates of each measurement auxiliary point (P) in the global coordinate system based on the measurement result of each measurement auxiliary point (P) in the laser tracker (M) participating in the measurement and the homogeneous conversion matrix between the laser tracker (M) participating in the measurement and the corresponding laser tracker (M);
s5, in the multi-laser tracker measurement field, assembling a target workpiece tool (2) on a reference workpiece tool (1), wherein a plurality of reference measurement points (11) are arranged on the reference workpiece tool (1), a plurality of target measurement points (21) are arranged on the target workpiece tool (2), and S5 comprises the following steps:
s51, fixing a reference workpiece tool (1), arranging a target workpiece tool (2) opposite to the reference workpiece tool (1), and connecting the target workpiece tool (2) with automatic butt joint equipment;
s52, g reference measuring points (11) and h target measuring points (21) in number, and obtaining theoretical positions { P) of the reference measuring points (11) on the reference workpiece tool (1) from an ideal assembly body model in three-dimensional softwarei M}＝{P1 M,P2 M,P3 M... } (i ═ 1,2,3.. g), and theoretical positions of the plurality of target measurement points (21) on the target workpiece tool (2)
Wherein i denotes the number of the plurality of reference measurement points (11) and j denotes the number of the plurality of target measurement points (21);
s53, through the multiple laser trackers (M) and the homogeneous conversion matrix { T between the multiple laser trackers (M)m nObtaining the actual measurement positions of the plurality of reference measurement points (11) on the reference workpiece tool (1) under the global coordinate system
Actual measurement positions of the target measurement points (21) on the target workpiece tool (2) in the global coordinate system
S54, according to the actual measurement positions { P) of the plurality of reference measurement points (11) on the reference workpiece tool (1) in the global coordinate systemi I}＝{P1 I,P2 I,P3 I.., establishing a reference tool coordinate system of a reference workpiece tool (1) and according to the actual measurement positions of the target measurement points (21) on the target workpiece tool (2) in the global coordinate system
Establishing a target tool coordinate system of a target workpiece tool (2);
s55, passing through the measured position { P) of the plurality of reference measurement points (11)i I}＝{P1 I,P2 I,P3 I.., and theoretical position Pi M}＝{P1 M,P2 M,P3 M.., solving a homogeneous transformation matrix T between the actual reference workpiece tool (1) and an ideal assembling body model in three-dimensional software1And is
S56, calculating a homogeneous transformation matrix T from an ideal assembly body model in three-dimensional software to an actual reference workpiece tool (1)0And T0＝(T1)-1；
S57, passing the measured positions of the target measuring points (21)
And theoretical position
Solving a homogeneous transformation matrix T between an actual target workpiece tool (2) and an ideal assembling body model in three-dimensional software2And is
S58, calculating a homogeneous transformation matrix T between the current actual measurement position and the ideal position of the target workpiece tool (2)3And T3＝T0·T2＝(T1)-1·T2And calculating the ideal positions of the target measuring points (21) of the target workpiece tool (2) in the ideal assembly state
S59, in the actual working space, the automatic butt joint equipment drives the target workpiece tool (2) to complete homogeneous transformation matrix T3And the defined space rigid body moves so as to assemble the target workpiece tool (2) to the reference workpiece tool (1).
2. The multi-laser-tracker-field-based involution pose alignment method according to claim 1, wherein the measurement auxiliary points (P) are a in number and the laser trackers (M) are b in number, and in step S3, the method comprises the steps of:
s31, numbering the b-th laser tracker (M) and the a-th measurement auxiliary points (P), respectively, such that the f-th (f is 1,2 … a) measurement auxiliary point (P) is measured by at least the M-th (M is 1,2 … b) laser tracker (M) and the n-th (n is 1,2 … b, n is not equal to M) laser tracker (M);
s32, the actual measurement result P of the f-th measurement auxiliary point (P) under the measurement of the M-th laser tracker (M) and the n-th laser tracker (M)fm＝(xfm,yfm,zfm)、Pfn＝(xfn,yfn,zfn) Are respectively converted into ball coordinate P'fm＝(rfm,αfm,βfm)、P'fn＝(rfn,αfn,βfn)；
S33, measuring the distance error parameter u by the laser tracker (M)rPitch angle error parameter uαAnd an azimuth error parameter uβConstructing a weight matrix
S34, setting the homogeneous conversion matrix between the mth laser tracker (M) and the nth laser tracker (M) as Tm nAnd said homogeneous transition matrix Tm nIncluding a transfer parameter RmnAnd tmnWherein R ismnIs a 3 x 3 matrix and represents the amount of rotation, t, between the measurement coordinate system of the mth laser tracker (M) and the measurement coordinate system of the nth laser tracker (M)mnIs a 3 x 1 matrix and represents the translation amount between the measurement coordinate system of the mth laser tracker (M) and the measurement coordinate system of the nth laser tracker (M), the homogeneous conversion matrix of all the laser trackers (M) is { T }m n}＝{T1 2,T1 3…T2 3,T2 4…T3 4…, and all homogeneous transformation matrices Tm nCorresponding transfer station parameter { R }mn}＝{R12,R13…R23,R24…R34…}、{tmn}＝{t12,t13…t23,t24…t34…}；
S35, estimating the estimation result of the f-th auxiliary measuring point (P) under the M-th laser tracker (M) according to the actual measurement result of the f-th auxiliary measuring point (P) under the n-th laser tracker (M)
Wherein g is a functional relationship;
s36, based on the Mahalanobis distance, constructing a reprojection error vector E of all the measurement auxiliary points (P), namely:
wherein, W in the formula E is the weight matrix W;
s37, using light beam adjustment method to give RmnAnd tmnInitial value, continuously adjusting RmnAnd tmnUntil E obtains the minimum value, stopping iteration, wherein the station transfer parameter corresponding to the minimum value of E is the solved { R }mnAnd tmn}。
3. The method for adjusting the combined attitude based on the multiple laser tracker measurement fields according to claim 1, wherein in step S59, the method comprises the steps of:
591, in the three-dimensional software, according to the actual measurement positions { P) of the plurality of reference measurement points (11) on the reference workpiece tool (1) in the global coordinate systemi I}＝{P1 I,P2 I,P3 I.., (i 1,2,3.. g) establishing a pre-assembly model of the reference workpiece tool (1), and passing the actual measurement positions of the target measurement points (21) on the target workpiece tool (2) in the global coordinate system
Establishing a preassembly model of a target workpiece tool (2), and transforming a matrix T by homogeneous times3The defined space rigid body motion completes virtual preassembly to complete a virtual preassembly model;
s592, finding out an interference area point { D ] on the pre-assembly model of the target workpiece tool (2) by comparing the virtual pre-assembly model with the ideal assembly model established in the step S1j}；
S593, solving a homogeneous transformation matrix T from the ideal assembling body model to the actual reference workpiece tool (1)4And T4＝(T2)-1Then interference region point { DjThe position of an interference area on an actual target workpiece tool (2)
S594, processing an interference area on the actual target workpiece tool (2);
s595, driving the target workpiece fixture (2) to complete homogeneous transformation matrix T by the automatic docking equipment3And the defined space rigid body moves so as to assemble the target workpiece tool (2) to the reference workpiece tool (1).
4. The multi-laser-tracker-measurement-field-based involutory posture adjustment method according to claim 1, wherein the accuracy between the measured position and the ideal measured position of the target workpiece fixture (2) is as follows, and the multi-laser-tracker-measurement-field-based involutory posture adjustment method further comprises the steps of:
s6, after the target workpiece tool (2) is assembled on the reference workpiece tool (1), current actual measurement positions of the target measurement points (21) on the target workpiece tool (2) in the global coordinate system are obtained through a plurality of laser trackers (M)
And calculating the current measured position
And the ideal position
Difference between them
S7，ERIf > S5-S6 are repeated until ER<, completing the assembly;
S8，ERif yes, the assembly is completed.
5. The method for adjusting the combined attitude based on the multiple laser tracker measurement fields according to claim 1, wherein in step S55, the method comprises the steps of:
s551, providing
S552, the actual measurement position coordinate of any reference measurement point (11) is
And theoretical position coordinates of
Selecting at least four reference measuring points (11), wherein the measured position coordinates and the theoretical position coordinates of the at least four reference measuring points (11) form a plurality of groups of data, namely, any group of data meets the following equation set:
s553, all the equation sets formed by the multiple data sets are combined to calculate T1Of (2) is performed.
6. The method for adjusting the combined attitude based on the multiple laser tracker measurement fields according to claim 1, wherein in step S57, the method comprises the steps of:
s571, setting
S572, the coordinate of the actual measurement position of the arbitrary target measurement point 21 is
And theoretical position coordinates of
Selecting at least four target measuring points (21), wherein the actual measurement position coordinates and the theoretical position coordinates of the at least four target measuring points (21) form a plurality of groups of data, namely anyOne set of data satisfies the following system of equations:
s573, simultaneously establishing all equation sets formed by the multiple groups of data to obtain T2Of (2) is performed.
7. The method for adjusting the attitude of a pair based on multiple laser tracker measurement fields according to claim 1, wherein in step S4, for each measurement auxiliary point (P):
when the global coordinate system is the measurement coordinate system of the laser tracker (M) participating in measuring the measurement auxiliary point (P), the coordinates of the measurement auxiliary point (P) under the global coordinate system are: -measurement of a laser tracker (M) defined as a global coordinate system;
when the global coordinate system is the measurement coordinate system of the laser tracker (M) which does not participate in measuring the measurement auxiliary point (P), the coordinates of the measurement auxiliary point (P) under the global coordinate system are:
directly multiplying the measurement result of the laser tracker (M) participating in the measurement by a homogeneous conversion matrix between the laser tracker (M) participating in the measurement and the laser tracker (M) defined as a global coordinate system; or
The measurement result of the laser tracker (M) involved in the measurement is multiplied by a homogeneous conversion matrix between the laser tracker (M) involved in the measurement and another laser tracker (M), and then multiplied by a homogeneous conversion matrix between the another laser tracker (M) and the laser tracker (M) defined as a global coordinate system.
8. The multi-laser-tracker-measurement-field-based involution attitude adjusting method according to claim 1, wherein the reference workpiece fixture (1) is a wing box framework of a wing, and the target workpiece fixture (2) is an upper skin and a shape-preserving fixture thereof.
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