CN111137468B - Multi-constraint-condition aircraft skin attitude adjusting method and system - Google Patents

Multi-constraint-condition aircraft skin attitude adjusting method and system Download PDF

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CN111137468B
CN111137468B CN201911327859.2A CN201911327859A CN111137468B CN 111137468 B CN111137468 B CN 111137468B CN 201911327859 A CN201911327859 A CN 201911327859A CN 111137468 B CN111137468 B CN 111137468B
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skin
assembled
pose
skeleton
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CN111137468A (en
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张继文
盖宇航
吴丹
陈恳
王国磊
徐静
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Tsinghua University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
    • B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
    • B64F5/10—Manufacturing or assembling aircraft, e.g. jigs therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64F—GROUND OR AIRCRAFT-CARRIER-DECK INSTALLATIONS SPECIALLY ADAPTED FOR USE IN CONNECTION WITH AIRCRAFT; DESIGNING, MANUFACTURING, ASSEMBLING, CLEANING, MAINTAINING OR REPAIRING AIRCRAFT, NOT OTHERWISE PROVIDED FOR; HANDLING, TRANSPORTING, TESTING OR INSPECTING AIRCRAFT COMPONENTS, NOT OTHERWISE PROVIDED FOR
    • B64F5/00—Designing, manufacturing, assembling, cleaning, maintaining or repairing aircraft, not otherwise provided for; Handling, transporting, testing or inspecting aircraft components, not otherwise provided for
    • B64F5/50—Handling or transporting aircraft components

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Abstract

The invention discloses a multi-constraint-condition aircraft skin attitude adjusting method and system, wherein the method comprises the following steps: acquiring relevant position data of the inner side and the outer side of the skeleton and the skin to be/assembled; processing the data to obtain the positions of characteristic holes on the skin to be assembled and the skeleton, point clouds of the outside surface type of the skeleton and the inside surface type of the skin to be assembled, an outside contour point set of the skin to be assembled/assembled and a pose solution set of the skin to be assembled under the condition of meeting a tolerance threshold by utilizing the point clouds; enabling the point sets to be in-place attitude solution sets, and calculating a sub-solution set of the skin to be assembled, wherein the sub-solution set meets the requirement below a tolerance threshold; calculating an optimal pose solution with an infinitely small assembly gap in a sub-solution set by using the characteristic hole position, the point cloud of the inner side of the skin to be assembled and the point set of the outer side outline; and judging whether the optimal pose solution exists, if so, carrying out a pose adjustment process according to the solution, otherwise, expanding a tolerance threshold, and iterating the process until a solution exists. The method can meet the requirement of the docking task on the premise of multi-tolerance constraint.

Description

Multi-constraint-condition aircraft skin attitude adjusting method and system
Technical Field
The invention relates to the technical field of large-scale airplane digital assembly, in particular to a digital posture adjusting method for a skin to be assembled when a plurality of tolerance constraints are generated in the assembly butt joint work of the skin and a framework in airplane assembly.
Background
In the process of airplane assembly, a large number of assembly problems between skins and skeletons are involved. With the increasing quality of airplanes, the requirements of ultra-maneuverability and stealth performance of military warplanes are increased continuously, and the requirements of the appearance precision of the airplanes are more strict. The assembly process, which is related to the accuracy of the profile of the aircraft, therefore needs to be strictly controlled. Tolerance requirements associated therewith include: the appearance precision of the airplane, the skin butt joint gap and the skin butt joint step difference.
Because the aircraft is in a high-speed motion state in the navigation process, each part of the aircraft body bears extremely large fatigue load, particularly the fatigue load of the skin to be assembled is the most serious. If the airplane is assembled with large assembling internal stress, the skin to be assembled is damaged during the process of bearing fatigue load, and the irreparable loss is caused. Therefore, the assembly process related to the internal assembly stress of the aircraft needs to be strictly controlled. Tolerance requirements associated therewith include: and assembling gaps between the skin and the framework.
The tolerance requirements for the skin to carcass butt-joint assembly process are multifaceted. In a skin-skeleton butt joint operation, typical constraint conditions include the shape precision of an aircraft, skin butt joint gaps, skin butt joint step differences, skin-skeleton assembly gaps and the like. For the skin at a special position, the assembling constraint conditions are more, and the constraint degree is stricter.
The traditional digital posture adjusting scheme only depends on positioning holes on skins and frameworks for posture adjustment. Before the posture is adjusted, the positions of the positioning holes of the skin and the framework in the butt joint area are measured, and the skin and the framework are butt jointed by matching the positioning holes of the skin and the framework. The design of the positioning holes only depends on an ideal digital model of the airplane, and due to the existence of manufacturing errors and assembly errors, the accurate alignment of the positioning holes does not mean that the butt joint quality of the skin and the skeleton is good, and related tolerance constraints cannot be guaranteed.
Based on the analysis, a more feasible optimal scheme is urgently needed, and a digital posture adjusting scheme is carried out by combining the surface type data of the skin and the skeleton.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
Therefore, the invention aims to provide a multi-constraint aircraft skin attitude adjusting method which can meet the requirement of a docking task under the premise of multi-tolerance constraint.
The invention also aims to provide a multi-constraint aircraft skin attitude adjusting system.
In order to achieve the above purpose, an embodiment of the invention provides an aircraft skin attitude adjusting method under multiple constraint conditions, which comprises the following steps: step S1, scanning to obtain first original data of the outer side surface type of the framework and the inner side surface type of the skin to be assembled and second original data of the outer side contour of the skin to be assembled and the outer side contour of the skin to be assembled, and measuring to obtain position data of characteristic holes in the skin to be assembled and the framework; step S2, processing the feature hole position data, the first original data and the second original data respectively to obtain a feature hole position on the skin to be assembled, a feature hole position on the skeleton, skeleton outer side surface type point clouds, an assembled skin outer side contour point set, a skin inner side surface type point cloud to be assembled and a skin outer side contour point set to be assembled; step S3, combining an airplane digital model, utilizing the point cloud of the inner side surface of the skin to be assembled and the point cloud of the outer side surface of the skeleton to calculate a pose solution set of the skin to be assembled under the condition that the pose solution set meets the appearance accuracy in a preset tolerance threshold; step S4, calculating a sub-solution set of the skin to be assembled meeting the skin butt seam clearance and the step tolerance in the preset wide tolerance threshold in the pose solution set by using the skin to be assembled outside contour point set and the assembled skin outside contour point set; step S5, calculating an optimal pose solution with characteristic holes being aligned and assembly gaps being infinitely close under the condition that the skin and the skeleton have no interference in the sub-solution set by using the characteristic hole positions on the skin to be assembled and the characteristic hole positions on the skeleton and the point cloud data of the inner side surface type of the skin to be assembled and the point cloud data of the outer side surface type of the skeleton; and S6, judging whether the optimal pose solution exists, if so, determining the optimal pose solution as an actual pose adjusting amount, outputting the optimal pose solution to a skin pose adjusting positioner for a pose adjusting process, if not, expanding the preset tolerance threshold to expand a solution set range, and iteratively executing the steps S3-S6 until a solution exists.
According to the aircraft skin posture adjusting method under the multiple constraint conditions, on the basis of traditional positioning based on the positioning holes, posture adjustment is carried out by combining surface type actual measurement data of the skin and the framework, and by adjusting posture adjusting parameters, on the basis of guaranteeing the tolerance requirements of the appearance precision, the skin butt joint gap and the skin butt joint step difference of the aircraft, the positioning holes are guaranteed to be involuted within a certain range, and the assembling gap between the skin and the framework is reduced as much as possible; in the data processing process, the influence of skin deformation on point cloud data obtained by scanning in the measurement process is eliminated, so that the subsequent skin sampling and feature extraction are more accurate, and meanwhile, the subsequent syndrome optimization solving process is greatly simplified by adopting a sampling method capable of determining the corresponding relation between the skin and the skeleton surface type point cloud.
In addition, the aircraft skin pose adjusting method with multiple constraint conditions according to the above embodiment of the present invention may further have the following additional technical features:
further, in one embodiment of the invention, the preset tolerance threshold comprises tolerance of aircraft profile precision, skin-to-seam clearance, skin-to-seam step difference and assembly clearance of skin and skeleton.
Further, in an embodiment of the present invention, the step S3 includes: registering the skeleton outer side profile of the airplane digital model to the skeleton outer side profile point cloud; calculating the pose of the inner side of the skin to be assembled of the airplane digifax under an assembly coordinate system; enabling the surface shape precision of the inner side of the skin to be assembled to approximately represent the appearance precision of the airplane, and expanding the inner side of the skin to be assembled of the airplane digifax to a feasible space according to the preset tolerance threshold; and searching the practical skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in the feasible space to obtain the pose solution set.
Further, in one embodiment of the invention, the inside pose of the skin to be assembled in the feasible space meets the shape precision of the airplane.
Further, in an embodiment of the present invention, the step S4 includes: registering the skin outer contour point set to be assembled to the assembled skin outer contour point set in the pose solution set range; and in the pose solution set range, on the premise of meeting the requirements of gap and step, searching the pose closest to the assembled skin outer contour point set in the skin outer contour point set to be assembled to obtain the sub solution set.
Further, in an embodiment of the present invention, the step S5 includes: in the sub-solution set, using the positions of the feature holes on the skin to be assembled and the positions of the skeleton feature holes, and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the skeleton to perform data registration; and solving the optimal pose solution which is in the sub-solution set range and ensures that the characteristic holes are as close as possible and the gaps are as small as possible on the premise that the skin to be assembled does not interfere with the framework.
In order to achieve the above object, an embodiment of the present invention provides an aircraft skin pose adjusting system with multiple constraint conditions, including: the acquisition module is used for scanning and acquiring first original data of the outer side surface type of the framework and the inner side surface type of the skin to be assembled and second original data of the outer side contour of the assembled skin and the outer side contour of the skin to be assembled, and measuring and acquiring position data of characteristic holes on the skin to be assembled and the framework; the data processing module is used for respectively processing the characteristic hole position data, the first original data and the second original data to obtain a characteristic hole position on the skin to be assembled, a characteristic hole position on the skeleton, skeleton outer side surface type point clouds, an assembled skin outer side contour point set, a skin inner side surface type point cloud to be assembled and a skin outer side contour point set to be assembled; the first hierarchical calculation module is used for calculating a pose solution set of the skin to be assembled under the condition that the pose solution set meets the external form precision in a preset tolerance threshold by combining an airplane digital model and utilizing the point cloud of the internal side surface of the skin to be assembled and the point cloud data of the external side surface of the skeleton; the second-level calculation module is used for calculating a sub-solution set of the skin to be assembled meeting the skin butt joint clearance and the step tolerance in the preset tolerance threshold in the pose solution set by using the skin to be assembled outside contour point set data and the assembled skin outside contour point set data; the third-level calculation module is used for calculating an optimal pose solution with characteristic holes being aligned and assembly gaps being infinitely close under the condition that the skins and the framework have no interference in the sub-solution set by utilizing the characteristic hole position data on the skins to be assembled and the characteristic hole position data on the framework, the point cloud data of the inner side surface of the skins to be assembled and the point set data of the outer side outline of the skins to be assembled; and the iteration expansion module is used for judging whether the optimal pose solution exists or not, if so, determining that the optimal pose solution is the actual pose adjustment amount, outputting the optimal pose solution to the skin pose adjustment positioner to perform a pose adjustment process, if not, expanding the preset tolerance threshold to expand the solution set range, and iteratively executing the first level calculation module, the second level calculation module and the third level calculation module.
According to the aircraft skin posture adjusting system with multiple constraint conditions, on the basis of traditional positioning based on positioning holes, posture adjustment is carried out by combining surface type measured data of skins and frameworks, and by adjusting posture adjusting parameters, on the basis of guaranteeing the tolerance requirements of the appearance precision, skin butt joint gap and skin butt joint step difference of an aircraft, the positioning holes are guaranteed to be involuted within a certain range, and the assembling gap between the skins and the frameworks is reduced as much as possible; in the data processing process, the influence of skin deformation on point cloud data obtained by scanning in the measurement process is eliminated, so that the subsequent skin sampling and feature extraction are more accurate, and meanwhile, the subsequent syndrome optimization solving process is greatly simplified by adopting a sampling method capable of determining the corresponding relation between the skin and the skeleton surface type point cloud.
In addition, the multi-constraint aircraft skin pose adjusting system according to the above embodiment of the present invention may further have the following additional technical features:
further, in one embodiment of the present invention, the first hierarchical computation module includes: the first matching unit is used for registering the skeleton outer side profile of the airplane digital model to the skeleton outer side profile point cloud; the computing unit is used for computing the pose of the inner side of the skin to be assembled of the airplane digifax under an assembly coordinate system; the expansion unit is used for enabling the surface shape precision of the inner side of the skin to be assembled to approximately represent the appearance precision of the airplane, and expanding the inner side of the skin to be assembled of the airplane digifax to a feasible space according to the preset tolerance threshold; and the first searching unit is used for searching the actual skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in the feasible space to obtain the pose solution set.
Further, in one embodiment of the present invention, the second hierarchy calculation module includes: the second matching unit is used for registering the skin outer contour point set to be assembled to the skin outer contour point set to be assembled in the pose solution set range; and the second searching unit is used for searching the pose closest to the assembled skin outer contour point set in the to-be-assembled skin outer contour point set to obtain the sub-solution set on the premise that the pose solution set range meets the requirements on gap and step difference.
Further, in one embodiment of the present invention, the third hierarchical computing module includes: and the third matching unit is used for performing data registration by using the positions of the feature holes on the skin to be assembled and the positions of the skeleton feature holes in the sub-solution set and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the skeleton, and solving the optimal pose solution which is as close as possible and has as small as possible gaps in the sub-solution set range on the premise that the skin to be assembled and the skeleton do not interfere with each other.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a flow chart of a multi-constraint aircraft skin pose adjustment method according to an embodiment of the invention;
FIG. 2 is a schematic diagram of an aircraft skin to frame docking assembly station in accordance with an embodiment of the present invention;
FIG. 3 is a schematic illustration of a gravitational deformation field of an aircraft skin in a state in accordance with an embodiment of the present invention;
FIG. 4 is a flow diagram of a method for multi-objective optimization based on a hierarchical sequence of bandwidth tolerances in accordance with an embodiment of the present invention;
FIG. 5 is a structural diagram of a multi-constraint aircraft skin pose adjustment system according to an embodiment of the invention.
Description of reference numerals:
the method comprises the following steps of 1-an aircraft skeleton, 2-a skin to be assembled, 3-an aircraft skeleton tool, 4-an aircraft skin tool, 5-a skin pose adjusting positioner, 6-an automatic scanning system, 7-a laser tracker, 8-an integrated control system, 9-an assembled skin, 10-an aircraft skin pose adjusting system with multiple constraint conditions, 100-an acquisition module, 200-a data processing module, 300-a first-level calculation module, 400-a second-level calculation module, 500-a third-level calculation module and 600-an iterative expansion module.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The method and the system for adjusting the attitude of the aircraft skin under multiple constraints according to the embodiment of the invention are described below with reference to the accompanying drawings, and firstly, the method for adjusting the attitude of the aircraft skin under multiple constraints according to the embodiment of the invention is described with reference to the accompanying drawings.
FIG. 1 is a flow chart of a multi-constraint aircraft skin pose adjustment method according to an embodiment of the invention.
As shown in fig. 1, the multi-constraint aircraft skin pose adjusting method includes the following steps:
in step S1, first raw data of the skeleton outer side profile and the skin inner side profile to be assembled and second raw data of the assembled skin outer side profile and the skin outer side profile to be assembled are obtained by scanning, and feature hole position data on the skin to be assembled and the skeleton are obtained by measurement.
Specifically, all required original data are obtained through measurement during assembly, all the original data are positioned in an assembly coordinate system to be in an assembly state before posture adjustment is carried out, the outer side face of the framework and the inner side face of the skin to be assembled are obtained through scanning, the original data of the outer side outline of the skin to be assembled and the outer side outline of the skin to be assembled are obtained through scanning, and the position data of characteristic holes in the skin and the framework are obtained through measurement.
In step S2, the feature hole position data, the first original data, and the second original data are processed respectively to obtain a feature hole position on the skin to be assembled, a feature hole position on the skeleton, a skeleton outer side surface point cloud, an assembled skin outer side contour point set, an assembled skin inner side surface point cloud, and an assembled skin outer side contour point set.
That is, after the data acquisition is completed, the data processing process is performed. The processed data includes:
the feature hole position data M1 on the skin to be assembled contains position data of a feature holes, and the form of the feature hole position data is marked as M1 ═ { MP ═ MPi|MPi＝(xmpi,ympi,zmpi) 1, 2.., a }; the point cloud number M2 of the skin inner side surface type to be assembled contains the position data of b sampling points, and the form is recorded as M2 ═ MSi|MSi＝(xmsi,ymsi,zmsi) 1, 2.., b }; the skin outside contour point set data M3 to be assembled contains position data of c contour points, which is in the form of M3 { ML ═ MLi|MLi＝(xmli,ymli,zmli),i＝1,2,...,c}；
The skeleton feature hole position data G1 similarly includes position data of a feature holes, and is expressed in the form of G1 ═ GPi|GPi＝(xgpi,ygpi,zgpi) 1, 2.., a }; the skeleton-outside-surface-type point cloud data G2 similarly includes position data of b sample points, and its form is denoted by G2 ═ GSi|GSi＝(xgsi,ygsi,zgsi) 1, 2.., b }; the set of skin-fitted outside contour points G3, likewise contains the position data for c contour points, which is denoted G3 ═ GLi|GLi＝(xgli,ygli,zgli),i＝1,2,...,c}。
And carrying out an optimal pose resolving process according to the processed data. The solving process needs to meet the tolerance of the appearance precision, the skin butt joint gap, the skin butt joint step difference and the assembly gap of the skin and the framework of the airplane in a preset tolerance threshold, and meanwhile, the characteristic hole positions are ensured to be as involutive as possible, and the gap between the skin and the framework is ensured to be as small as possible. The importance degrees of the tolerance constraints are different, so that a multi-objective optimization method of a bandwidth-tolerant hierarchical sequence is used for solving the optimal pose of skin assembly to be assembled, wherein the optimal pose needs to meet the following requirements: the aircraft contour precision meets the tolerance requirement, the skin butt joint gap and the step difference meet the tolerance requirement, the skin and the skeleton feature holes are aligned as much as possible, the butt joint of the skin and the skeleton has no interference, and the assembly gap is as small as possible. As shown in fig. 2, an implementation process of solving the optimal pose by the multi-objective optimization method based on the bandwidth tolerant hierarchical sequence is as follows, in steps S3 to S5:
in step S3, the pose solution set of the skin to be assembled under the skin contour accuracy meeting the preset tolerance threshold is calculated by using the skin inside contour point cloud and the skeleton outside contour point cloud in combination with the airplane digifax.
In other words, the solution set of the pose of the skin to be assembled on the premise of meeting the appearance accuracy is calculated by combining the airplane digital model and using the point cloud of the inner side surface of the skin to be assembled and the point cloud of the outer side surface of the skeleton.
Further, in an embodiment of the present invention, the step S3 includes:
registering the skeleton outer side profile of the airplane digital model to skeleton outer side profile point cloud;
calculating the pose of the inner side of the skin to be assembled of the airplane digifax under an assembly coordinate system;
the surface shape precision of the inner side of the skin to be assembled is enabled to approximate the appearance precision of the airplane, and the inner side of the skin to be assembled of the airplane digifax is enlarged to a feasible space according to a preset tolerance threshold;
and searching the actual skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in a feasible space to obtain a pose solution set.
And the inner side pose of the skin to be assembled in the feasible space meets the appearance precision of the airplane.
The specific implementation process is as follows:
firstly, registering the skeleton outer side profile of the airplane digital model to the skeleton outer side profile point cloud. And calculating the pose of the inner side of the skin to be assembled of the airplane digifax under the assembly coordinate system.
And the shape accuracy of the inner side of the skin to be assembled is used for approximately representing the shape accuracy of the airplane.
And expanding the inner side of the skin to be assembled of the airplane digifax into a feasible space according to the shape tolerance. All skin poses in the feasible space meet the requirement of appearance precision.
Firstly, searching the actual skin pose of the inner side of the skin to be assembled closest to the airplane digifax in a feasible space:
Figure GDA0003114939640000071
Figure GDA0003114939640000072
in the formula, dis is a distance function from b sampling points in the to-be-assembled skin inner side type point cloud data M2 to the to-be-assembled skin inner side of the airplane digifax; when the actual skin is positioned above the digital analogy in the Z direction, the distance is positive, otherwise, the distance is negative;
Figure GDA0003114939640000073
is the appearance tolerance range corresponding to the ith sampling point;
Figure GDA0003114939640000074
the pose of the skin to be assembled on the inner side of the skin to be assembled, which is closest to the airplane digital model, meets the requirement of the appearance precision.
The solution set of step S3 is obtained after adding a tolerance threshold to the optimal solution of this step. The preset tolerance threshold is set as:
Figure GDA0003114939640000075
the solution set of step S3 is expressed as:
Figure GDA0003114939640000076
in step S4, using the skin outside contour point set to be assembled and the skin outside contour point set already assembled, and in the pose solution set, calculating a sub-solution set of the skin to be assembled that meets the skin butt-joint gap and the step tolerance in the preset tolerance threshold.
That is, using the skin outside contour point set to be assembled and the skin outside contour point set already assembled, in the solution set of step S3, a sub-solution set is calculated in which the skin to be assembled satisfies the skin butt seam clearance and the step tolerance.
Further, in an embodiment of the present invention, the step S4 includes:
in the range of the pose solution set, registering the outer contour point set of the skin to be assembled to the outer contour point set of the assembled skin;
and in the pose solution set range, on the premise of meeting the requirements of gap and step, searching the pose closest to the assembled skin outer contour point set in the skin outer contour point set to be assembled to obtain a sub solution set.
The specific implementation process is as follows:
in solution set X1In the range, data registration is carried out by using a skin outer contour point set M3 to be assembled and an assembled skin outer contour point set G3. Find in solution set X1In the range, on the premise of meeting the requirements of the butt seam clearance and the step difference, the position and posture of the skin outer contour point set to be assembled are closest to the position and posture of the assembled skin outer contour point set.
Figure GDA0003114939640000077
Figure GDA0003114939640000078
Figure GDA0003114939640000079
In the formula (di)lxy,dislzCalculating a butt seam gap function and a butt seam step difference function between sampling points corresponding to the skin outer contour point set M3 to be assembled and the skin outer contour point set G3. When the outer profile of the skin to be assembled is atDis when located over the outer profile of the assembled skin in the Z-directionlzThe distance is positive, otherwise negative. Dis when there is a gap between the outer contour of the skin to be assembled and the outer contour of the assembled skinlxyThe distance is positive and the interference is negative.
Figure GDA0003114939640000081
Is the gap tolerance range corresponding to the ith contour point.
Figure GDA0003114939640000082
Is the tolerance range of the gap difference corresponding to the ith contour point.
Figure GDA0003114939640000083
Is solution set X1And the pose of the skin to be assembled, which is closest to the outer profile of the assembled skin, meets the requirements of the skin butt-joint gap and the step difference.
The solution set of step S4 is obtained after adding a tolerance threshold to the optimal solution of this step. Tolerance threshold set to
Figure GDA0003114939640000084
The solution set of step S4 is expressed as:
Figure GDA0003114939640000085
it will be appreciated that the latter sub-solution set of the above process is dependent on the previous solution set. The solution set of each step is obtained by solving the optimal solution in the step and adding a tolerance threshold to the optimal solution in the step.
In step S5, using the feature hole positions on the skin to be assembled and the feature hole positions on the skeleton, and the point cloud of the skin inner side surface and the point cloud of the skeleton outer side surface, in the case of a sub-solution set, under the condition that there is no interference between the skin and the skeleton, an optimal pose solution in which the feature holes tend to align and the assembly gap approaches infinitely is calculated.
That is, using the positions of the feature holes on the skin and the skeleton, the point cloud of the inner side of the skin to be assembled and the point cloud of the outer side of the skeleton, in the sub-solution set of step S4, a pose solution is calculated in which the feature holes are aligned as much as possible, the butt joint of the skin and the skeleton is not interfered, and the assembly gap is as small as possible. And taking the pose solution at the moment as the optimal pose of the practical application in the whole assembly.
Further, in an embodiment of the present invention, the step S5 includes:
in the sub-solution set, using the positions of the characteristic holes on the skin to be assembled and the positions of the characteristic holes of the framework, and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the framework to carry out data registration;
and in the range of the sub-solution set, on the premise that the skin to be assembled does not interfere with the framework, the optimal pose solution which is as close as possible to the characteristic holes and as small as possible in gaps is obtained.
The specific implementation process is as follows:
in solution set X2In the range, the skin characteristic hole position data M1 and the skeleton characteristic hole position data G1 are used, and the skin inner side point cloud data M2 and the skeleton outer side point cloud data G2 to be assembled are combined for data registration. Find in solution set X2In the range, under the premise that the skin does not interfere with the framework, the poses that the characteristic holes are as close as possible and the gaps are as small as possible are ensured.
Figure GDA0003114939640000091
Figure GDA0003114939640000092
Figure GDA0003114939640000093
In the formula (di)s,dispThe method is used for calculating a skin-skeleton clearance function and a skin-skeleton characteristic hole circle center distance function. When the inner side of the skin to be assembled is in the Z directionAt the outer upper side of the skeleton, diss,dispThe distance is positive, otherwise, negative;
Figure GDA0003114939640000094
the range of the gap between the skin and the framework corresponding to the ith sampling point is shown;
Figure GDA0003114939640000095
the tolerance range of the distance between the skin corresponding to the ith characteristic hole and the circle center of the skeleton characteristic hole is obtained;
Figure GDA0003114939640000096
is solution set X2In the process, on the premise of ensuring that the skin does not interfere with the framework, the optimal pose with the characteristic holes as close as possible and the gaps as small as possible is also the final solution for resolving the whole optimal pose.
In step S6, it is determined whether the optimal pose solution exists, if so, the optimal pose solution is determined to be the actual pose adjustment amount, and the optimal pose solution is output to the skin pose adjustment positioner for the pose adjustment process, if not, the preset tolerance threshold is expanded to expand the solution set range, and steps S3-S6 are iteratively executed until a solution exists.
The method can meet the requirement of skin optimal pose calculation in most of the docking tasks of skins and skeletons. If the solution set has a solution, outputting the optimal pose of the skin to a skin pose adjusting positioner according to the solution, and finishing a corresponding pose adjusting process by the skin pose adjusting positioner when the pose adjusting positioning is required; when the solution set is empty, the tolerance threshold can be properly expanded on the premise of ensuring tolerance constraint to expand the solution set range, and if the solution set is still empty, the tolerance threshold can be continuously expanded, so that the method becomes a space search method and searches whether pose solutions meeting all constraints exist. If so, judging whether the current pose solution can be the most practical pose adjustment amount by people; if not, the manufacturing tolerance of the skin is too large, and the out-of-tolerance position needs to be repaired.
The method for adjusting the attitude of the aircraft skin under multiple constraint conditions of the invention is described in detail below with reference to specific embodiments.
As shown in fig. 2, the method of the present invention is implemented on an aircraft component, with the following specific steps:
the aircraft component assembling station comprises an aircraft framework 1, a skin 2 to be assembled, an aircraft framework tool 3, an aircraft skin tool 4, a skin posture adjusting positioner 5, an automatic scanning system 6, a laser tracker 7, an integrated control system 8 and an assembled skin 9. The skin and the framework are assembled in a butt joint mode in an assembling station.
The aircraft framework tool 3 is fixed on the ground, the aircraft framework 1 is fixed with the aircraft framework tool 3, the aircraft framework 1 is assembled in the assembly station, and the assembled skin 9 is assembled on the aircraft framework 1. A series of characteristic holes are designed and prefabricated on the airplane framework 1 according to a theoretical digital model and are used for assisting butt joint assembly work.
The skin 2 to be assembled is fixed on the aircraft skin tool 4 through two forms of a sucking disc and a mechanical clamping jaw. The aircraft skin tool 4 is connected to the skin pose adjusting positioner 5 through a spherical hinge type joint. The skin posture-adjusting positioner 5 is fixed on the ground of the standing position. A series of characteristic holes are designed and prefabricated according to a theoretical digital model correspondingly to the skin 2 to be assembled and are used for assisting butt joint assembly work.
The automatic scanning system 6 is matched with the laser tracker 7 for use, and scans to obtain the data of the outer side of the framework and the inner side of the skin to be assembled. The automatic scanning system 6 includes an industrial robot having a moving function, a line laser scanning head, and a controller. Industrial robots provide for the movement of a line laser scanning head. The laser tracker 7 measures the pose of the line laser scanning head and integrates the pose into a surface point cloud by combining the data obtained by scanning. The controller realizes the data synchronization of the line laser scanning head and the laser tracker. The laser tracker 7 can also perform characteristic hole position measurements of the airframe 1 and of the skin 2 to be assembled.
The skin pose adjusting positioner 5 comprises a series of numerical control positioners and can adjust a workpiece assembled on the system to any pose within a certain range.
The integrated control system 8 performs the following functions: controlling the scanning path of the automatic scanning system 6; receiving the measurement data of the automatic scanning system 6 and the laser tracker 7; data processing and optimal pose resolving; and controlling the skin posture-adjusting positioner 5 to complete the butt joint assembly of the skin and the framework.
The direction of the assembly coordinate system is established according to the direction of the butt joint surface of the airplane framework 1 and the skin 2 to be assembled. And taking the fitting plane of the butt joint surface as an X-Y plane and the fitting method direction of the butt joint surface as a Z direction.
In the initial state, the airplane framework 1 and the skin 2 to be assembled are not butted, and a certain space is reserved. Within the reserved space, the automatic scanning system 6 performs a surface type scanning operation. All measurements in the assembly station have been converted to the assembly coordinate system.
The specific process of executing the data acquisition process, i.e., step S1, is as follows:
s101, importing a skin digital-analog, a skeleton digital-analog and a station structure form to be assembled into the integrated control system 8, and making an automatic scanning track by the integrated control system 8 according to the input information of the step S101;
s102, the scanning trajectory is output to the automatic scanning system 6, and the automatic scanning system 6 starts to perform data acquisition. The collected data content is as follows: the outer side profile of the framework and the inner side profile of the skin to be assembled, and the outer side profile of the assembled skin and the outer side profile of the skin to be assembled;
s103, measuring the positions of the characteristic holes on the skin and the skeleton by using a laser tracker 7;
and S104, transmitting the surface type data, the contour data and the characteristic hole position data to the integrated control system 8 to finish data acquisition.
And after the data acquisition is finished, executing a data processing process. The raw data collected has a lot of noise and redundant information, and the data is coupled with the deformation state of the skin, so the raw data needs to be processed. That is, the data processing procedure of step S2 is as follows:
step S201, in the integrated control system 8, according to the theoretical models of the skin 2 to be assembled and the aircraft skin tool 4, calculating the gravity deformation distribution of the skin in a scanning state by using a finite element method. Loading the obtained in step S104And matching the inner side surface of the skin, matching the outer side profile of the skin to be assembled, and performing gravity deformation compensation on the position of the characteristic hole on the skin to be assembled so as to restore the skin to a state without gravity deformation, and finally obtaining measurement data decoupled from gravity deformation. The feature hole position data M1 on the skin to be fitted contains position data of a feature holes, which is in the form of M1 ═ MPi|MPi＝(xmpi,ympi,zmpi),i＝1,2,...,a}；
Step S202, in the integrated control system 8, filtering the inner side profile of the skin to be assembled and the outer side profile of the skin to be assembled, which are decoupled through gravity deformation, by using a filtering program to remove noise points;
step S203, in the integrated control system 8, the filtered skin inside profile to be assembled obtained in step S202 is sampled by using a sampling program, so as to obtain an ordered skin inside profile point cloud to be assembled. The inner side type point cloud data M2 of the mask to be assembled contains the position data of b sampling points, and the form is recorded as M2 ═ MSi|MSi＝(xmsi,ymsi,zmsi),i＝1,2,…,b}；
Step S204, in the integrated control system 8, extracting the contour features of the filtered outer contour of the skin to be assembled obtained in the step S202 by using a feature extraction program, and intercepting a contour point set of a butt joint area of the skin to be assembled to obtain a contour point set of the outer contour of the skin to be assembled. The skin outside contour point set data M3 to be assembled contains position data of c contour points, which is in the form of M3 { ML ═ MLi|MLi＝(xmli,ymli,zmli),i＝1,2,…,c}；
And step S205, checking the influence of the gravity deformation on the framework. Generally, because the structural form of the framework determines that the framework is not easily influenced by gravity deformation, the gravity deformation compensation of the outer profile of the skin to be assembled and the position of the characteristic hole on the framework is not performed on the outer side profile of the framework obtained in the step S104. The skeleton feature hole position data G1 similarly includes position data of a feature holes, and is denoted by the format G1 ═ GPi|GPi＝(xgpi,ygpi,zgpi),i＝1,2,…,a}；
Step S206, in the integrated control system 8, filtering the outer side profile of the skeleton and the outer side profile of the assembled skin by using a filtering program to remove noise points;
step S207, in the integrated control system 8, the filtered skeleton outer side surface type obtained in step S206 is sampled by using a sampling program, so as to obtain an ordered skeleton outer side surface type point cloud. And combining a theoretical digital model and a specific sampling rule, wherein the sampled point clouds on the outer side surface of the skeleton correspond to the point clouds on the inner side surface of the skin to be assembled one by one. The skeleton outside surface point cloud data G2 similarly includes position data of b sample points, and its form is denoted by G2 ═ GSi|GSi＝(xgsi,ygsi,zgsi),i＝1,2,…,b}；
In step S208, in the integrated control system 8, a feature extraction program is used to extract contour features from the filtered assembled skin outer contour obtained in step S206, so as to obtain an assembled skin outer contour point set. And combining the theoretical digital model and the nearest point iterative registration, wherein the assembled skin outer contour point set corresponds to the skin outer contour point set to be assembled one by one. The set of skin-fitted outside contour points G3 likewise contains position data for c contour points, which is denoted G3 ═ GLi|GLi＝(xgli,ygli,zgli),i＝1,2,...,c}。
It can be understood that, in step S201, the gravity deformation compensation has the following benefits: the skin should be stress-free in the best condition after assembly is complete, otherwise fatigue damage and the like are prone to occur. I.e. the skin is in a non-deformed state after assembly is completed. However, in the case of a skin in the assembly station, which is a deformation, the surface shape data acquired by scanning using the automatic scanning system 6 is coupled to the deformation. This deformation occurs because the skin 2 to be assembled and the aircraft skin tooling 4 are positioned in the air in the form of multi-point support by the skin pose locator 5. The measured data are decoupled from the gravity deformation, and the final optimal pose resolving precision can be improved.
It should be noted that, the specific implementation manner of gravity deformation compensation in the embodiment of the present invention is as follows:
the deformation compensation is performed using a finite element method. Recording all points p in the point cloud before compensationiIs expressed as pi|Pi＝(xi,yi,zi) I 1, 2. The method comprises the steps of constructing a finite element model according to product size information and weight information of a skin 2 to be assembled and an aircraft skin tool 4, defining constraint between the finite element model and an environment on the basis, and applying a gravity load to the finite element model in a simulation environment. Since the rigidity in the Z direction of the skin 2 to be assembled and the aircraft skin tool 4 is poor, the deformation in the Z direction is significant. As shown in fig. 3, the gravity deformation field δ z is f (x, y). According to the deformation field information, Z-direction deflection of each point can be calculated and solved, and then the corresponding deflection value is compensated for the Z-direction coordinate of each point in the point cloud. All points in the compensated point cloud
Figure GDA0003114939640000121
Is represented by
Figure GDA0003114939640000122
In other embodiments, the direction of gravity in the assembly coordinate system needs to be determined according to actual conditions, and may not be the same as the Z direction, which is not specifically limited herein.
In steps S203 and S207, a specific implementation of the sampling method capable of defining the correspondence between the inside of the skin to be assembled and the outside surface type point cloud data of the skeleton is as follows: since the correspondence of the skin 2 to be fitted to the characteristic holes of the aircraft skeleton 1 is known, and the positions of these characteristic holes have been measured by means of the laser tracker 7. In the point cloud data of the types of the inner side of the skin to be assembled and the outer side of the skeleton, the corresponding relation of the characteristic holes is unchanged. According to a group of characteristic holes with known corresponding relations between skins and frameworks, the surface types of the skins and the frameworks are divided into independent subintervals with a certain micro length as a step length along two orthogonal directions in an X-Y plane, and the corresponding relations between the subintervals are in one-to-one correspondence.
And positioning the filtered point cloud data of the inner side of the skin to be assembled and the outer side surface of the skeleton into each subinterval. And taking the center of the subinterval as a sampling point, and taking the coordinate mean value of all points in the sub-area in the Z direction as the coordinate value of the sampling point in the Z direction. And carrying out the same operation on each subinterval to finish the data sampling process.
In steps S204 and S208, a specific implementation manner capable of specifying the corresponding relationship between the skin to be assembled and the assembled skin outer contour point set is as follows: firstly, the outer side contour of the skin to be assembled and the outer side contour of the assembled skin are projected to an X-Y plane. And then extracting an outer contour point set of the skin to be assembled and an outer contour point set of the assembled skin from the projected plane point cloud file. And intercepting the point set data of the butt-joint areas of the two skins according to the digital model. And determining the corresponding relation of the point sequence by using an iteration closest point method.
The specific implementation scheme for extracting the contour point set from the projected plane point cloud file is as follows: the method comprises the steps of firstly centralizing plane point clouds, and then converting all the point clouds into a polar coordinate form from rectangular coordinates. And taking the point cloud center as a vertex, and equally dividing the plane into a plurality of angle ranges. In each angular range, the point with the largest radius is extracted. The extracted points are integrated over all angular ranges, and the points are again transformed to rectangular coordinates and de-centered. Finally, a set of contour points is obtained.
And carrying out an optimal pose resolving process according to the processed data. The solving process needs to meet tolerance constraints of the appearance precision, the skin butt joint gap, the skin butt joint step difference and the assembly gap of the skin and the framework of the airplane. The importance degrees of the tolerance constraints (preset tolerance thresholds) are different, so that the optimal pose for assembling the skin to be assembled is solved by using a multi-objective optimization method of a bandwidth-tolerant hierarchical sequence. This optimum pose satisfies:
(1) the shape precision of the airplane meets the tolerance requirement;
(2) the skin butt joint gap and the step difference meet the tolerance requirement;
(3) the characteristic holes of the skin and the skeleton are aligned as much as possible, the butt joint of the skin and the skeleton has no interference, and the assembly clearance is as small as possible.
As shown in fig. 4, the specific implementation of solving the optimal pose by the multi-objective optimization method based on the bandwidth tolerant hierarchical sequence is as follows:
step S3, combining with the airplane digital model, using the skin inner side point cloud and the skeleton outer side point cloud obtained in the steps S203 and S207 to calculate the pose solution set of the skin to be assembled on the premise of meeting the appearance accuracy;
step S4, calculating a sub-solution set of the skin to be assembled, which meets the skin butt seam clearance and the step tolerance, in the solution set of the step S3 by using the skin to be assembled outside contour point set and the skin assembled outside contour point set obtained in the steps S204 and S208;
step S5, using steps S201 and S205 to obtain the positions of the characteristic holes on the skin and the skeleton, steps S203 and S207 to obtain the point cloud of the inner side surface of the skin to be assembled and the point cloud of the outer side surface of the skeleton, and step S4, in the subset of steps, calculating the solution that the characteristic holes are aligned as much as possible, the butt joint of the skin and the skeleton has no interference, and the assembly gap is as small as possible. Taking the pose solution at the moment as the optimal pose of the actual application in the whole assembly;
and step S6, the multi-objective optimization method based on the bandwidth tolerant hierarchical sequence can meet the requirement of skin optimal pose resolving in most of the docking tasks of skins and skeletons. If the solution set has a solution, outputting the optimal pose of the skin to the skin pose adjusting positioner 5 according to the solution, and finishing the corresponding pose adjusting process by the skin pose adjusting positioner 5 when the pose adjusting positioning is required; when the solution set is empty, the tolerance threshold can be properly expanded on the premise of ensuring tolerance constraint to expand the solution set range, and if the solution set is still empty, the tolerance threshold can be continuously expanded, so that the method becomes a space search method and searches whether pose solutions meeting all constraints exist. If so, judging whether the current pose solution can be the most practical pose adjustment amount by people; if not, the manufacturing tolerance of the skin is too large, and the out-of-tolerance position needs to be repaired.
Compared with the traditional docking scheme only depending on the positioning hole, the aircraft skin posture adjusting method under the multi-constraint condition comprehensively considers the influence of multiple tolerances in the docking process of the aircraft skin and the framework, and can meet the docking task requirement under the premise of multi-tolerance constraint; by a multi-objective optimization method of a bandwidth-tolerant hierarchical sequence, the pose resolution of the skin constrained by multiple tolerances is realized, the assembly tolerance is optimized in a hierarchical level according to the importance degree, the requirement of the front tolerance of the optimization hierarchy is strictly met, and the characteristic holes are ensured to be as close as possible and the gaps are ensured to be as small as possible on the premise that the skin does not interfere with the framework by the optimization solution of the last level; influence of skin deformation on point cloud data obtained by scanning in the measurement process is eliminated in the data processing process, so that subsequent skin sampling and feature extraction are more accurate; and a sampling method capable of determining the corresponding relation between the skin and the skeleton surface type point cloud is adopted, so that the subsequent bit optimization solving process is greatly simplified.
The airplane skin pose adjusting system with multiple constraint conditions proposed by the embodiment of the invention is described next with reference to the attached drawings.
FIG. 5 is a structural diagram of a multi-constraint aircraft skin pose adjustment system according to an embodiment of the present invention.
As shown in fig. 5, the system 10 includes: an acquisition module 100, a data processing module 200, a first hierarchy computation module 300, a second hierarchy computation module 400, a third hierarchy computation module 500, and an iterative expansion module 600.
The obtaining module 100 is configured to scan and obtain first original data of a skeleton outer side profile and a skin inner side profile to be assembled and second original data of an assembled skin outer side profile and a skin outer side profile to be assembled, and measure and obtain feature hole position data of the skin to be assembled and the skeleton.
The data processing module 200 is configured to process the feature hole position data, the first original data, and the second original data, respectively, to obtain a feature hole position on the skin to be assembled, a feature hole position on the skeleton, a skeleton outer side surface type point cloud, an assembled skin outer side contour point set, an assembled skin inner side surface type point cloud, and an assembled skin outer side contour point set.
The first hierarchical computing module 300 is configured to compute a pose solution set of the skin to be assembled in the form accuracy meeting a preset tolerance threshold by using the point cloud of the inner side of the skin to be assembled and the point cloud of the outer side of the skeleton in combination with the airplane digifax.
Further, in one embodiment of the present invention, the first hierarchical computation module 300 includes:
the first matching unit is used for registering the skeleton outer side surface type of the airplane digital model to the skeleton outer side surface type point cloud;
the computing unit is used for computing the pose of the inner side of the skin to be assembled of the airplane digifax under the assembly coordinate system;
the expansion unit is used for enabling the surface shape precision of the inner side of the skin to be assembled to approximately represent the appearance precision of the airplane, and expanding the inner side of the skin to be assembled of the airplane digifax to a feasible space according to a preset tolerance threshold;
and the first searching unit is used for searching the actual skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in a feasible space to obtain a pose solution set.
The second-level calculation module 400 is configured to calculate, in the pose solution set, a sub-solution set in which the skin to be assembled meets skin butt-joint gaps and step tolerance in a preset wide tolerance threshold, by using the data of the skin outside contour point set to be assembled and the data of the skin outside contour point set already assembled.
Further, in one embodiment of the present invention, the second hierarchy computing module 400 includes:
the second matching unit is used for registering the skin outer contour point set to be assembled to the skin outer contour point set already assembled in the range of the pose solution set;
and the second searching unit is used for searching the pose closest to the assembled skin outer contour point set in the skin outer contour point set to be assembled to obtain a sub-solution set on the premise of solving the pose solution set range and meeting the requirements on the gap and the step difference.
The third hierarchical computing module 500 is configured to compute an optimal pose solution in which feature holes tend to align and assembly gaps approach infinitely under the condition that the skin and the skeleton have no interference in the sub-solution set by using the feature hole position data on the skin to be assembled and the feature hole position data on the skeleton, and the inner side point cloud data of the skin to be assembled and the inner side point cloud data of the skeleton.
Further, in one embodiment of the present invention, the third hierarchical computation module 500 includes:
and the third matching unit is used for performing data registration by using the positions of the characteristic holes and the positions of the skeleton characteristic holes on the skin to be assembled and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the skeleton in the sub-solution set, and solving the optimal pose solution which ensures that the characteristic holes are as close as possible and the gap is as small as possible on the premise that the skin to be assembled and the skeleton do not interfere.
The iterative expansion module 600 is configured to determine whether an optimal pose solution exists, determine that the optimal pose solution is an actual pose adjustment amount if the optimal pose solution exists, output the optimal pose solution to the skin pose adjustment locator to perform a pose adjustment process, expand a preset tolerance threshold to expand a solution set range if the optimal pose solution does not exist, continue to execute the first-level calculation module, the second-level calculation module, and the third-level calculation module, and continuously perform the iterative expansion module, the first-level calculation module, the second-level calculation module, and the third-level calculation module in an iterative manner, so that an optimal pose solution can be obtained.
Compared with the traditional docking scheme only depending on the positioning hole, the aircraft skin posture adjusting system with multiple constraint conditions provided by the embodiment of the invention comprehensively considers the influence of multiple tolerances in the docking process of the aircraft skin and the framework, and can meet the docking task requirement on the premise of multiple tolerance constraints; by a multi-objective optimization method of a bandwidth-tolerant hierarchical sequence, the pose resolution of the skin constrained by multiple tolerances is realized, the assembly tolerance is optimized in a hierarchical level according to the importance degree, the requirement of the front tolerance of the optimization hierarchy is strictly met, and the characteristic holes are ensured to be as close as possible and the gaps are ensured to be as small as possible on the premise that the skin does not interfere with the framework by the optimization solution of the last level; influence of skin deformation on point cloud data obtained by scanning in the measurement process is eliminated in the data processing process, so that subsequent skin sampling and feature extraction are more accurate; and a sampling method capable of determining the corresponding relation between the skin and the skeleton surface type point cloud is adopted, so that the subsequent bit optimization solving process is greatly simplified.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A multi-constraint-condition aircraft skin attitude adjusting method is characterized by comprising the following steps:
step S1, scanning to obtain first original data of the outer side surface type of the framework and the inner side surface type of the skin to be assembled and second original data of the outer side contour of the skin to be assembled and the outer side contour of the skin to be assembled, and measuring to obtain position data of characteristic holes in the skin to be assembled and the framework;
step S2, processing the feature hole position data, the first original data and the second original data respectively to obtain a feature hole position on the skin to be assembled, a feature hole position on the skeleton, skeleton outer side surface type point clouds, an assembled skin outer side contour point set, a skin inner side surface type point cloud to be assembled and a skin outer side contour point set to be assembled;
step S3, combining an airplane digital model, utilizing the point cloud of the inner side surface of the skin to be assembled and the point cloud of the outer side surface of the skeleton to calculate a pose solution set of the skin to be assembled under the condition that the pose solution set meets the appearance accuracy in a preset tolerance threshold;
step S4, calculating a sub-solution set of the skin to be assembled meeting the skin butt seam clearance and the step tolerance in the preset wide tolerance threshold in the pose solution set by using the skin to be assembled outside contour point set and the assembled skin outside contour point set;
step S5, calculating an optimal pose solution with characteristic holes being aligned and assembly gaps being infinitely close under the condition that the skin and the skeleton have no interference in the sub-solution set by using the characteristic hole positions on the skin to be assembled and the characteristic hole positions on the skeleton and the point cloud data of the inner side surface type of the skin to be assembled and the point cloud data of the outer side surface type of the skeleton; and
and S6, judging whether the optimal pose solution exists, if so, determining the optimal pose solution as an actual pose adjusting amount, collecting the optimal pose solution to a skin pose adjusting positioner to carry out a pose adjusting process, if not, expanding the preset tolerance threshold to expand the solution collection range, and iteratively executing the steps S3-S6 until a solution exists.
2. The multi-constraint aircraft skin pose adjustment method according to claim 1, wherein the preset tolerance threshold comprises the tolerance of the aircraft appearance precision, the skin butt seam gap, the skin butt seam step difference and the assembly gap of the skin and the framework.
3. The multi-constraint aircraft skin pose adjusting method according to claim 1, wherein the step S3 comprises:
registering the skeleton outer side profile of the airplane digital model to the skeleton outer side profile point cloud;
calculating the pose of the inner side of the skin to be assembled of the airplane digifax under an assembly coordinate system;
enabling the surface shape precision of the inner side of the skin to be assembled to approximately represent the appearance precision of the airplane, and expanding the inner side of the skin to be assembled of the airplane digifax to a feasible space according to the preset tolerance threshold;
and searching the practical skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in the feasible space to obtain the pose solution set.
4. The multi-constraint-condition aircraft skin pose adjustment method according to claim 3, wherein the inner side poses of the skins to be assembled in the feasible space all meet the aircraft appearance precision.
5. The multi-constraint aircraft skin pose adjusting method according to claim 1, wherein the step S4 comprises:
registering the skin outer contour point set to be assembled to the assembled skin outer contour point set in the pose solution set range;
and in the pose solution set range, on the premise of meeting the requirements of gap and step, searching the pose closest to the assembled skin outer contour point set in the skin outer contour point set to be assembled to obtain the sub solution set.
6. The multi-constraint aircraft skin pose adjusting method according to claim 1, wherein the step S5 comprises:
in the sub-solution set, using the positions of the feature holes on the skin to be assembled and the positions of the skeleton feature holes, and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the skeleton to perform data registration;
and solving the optimal pose solution which is in the sub-solution set range and ensures that the characteristic holes are as close as possible and the gaps are as small as possible on the premise that the skin to be assembled does not interfere with the framework.
7. The utility model provides an aircraft skin accent appearance system of many constraints which characterized in that includes:
the acquisition module is used for scanning and acquiring first original data of the outer side surface type of the framework and the inner side surface type of the skin to be assembled and second original data of the outer side contour of the assembled skin and the outer side contour of the skin to be assembled, and measuring and acquiring position data of characteristic holes on the skin to be assembled and the framework;
the data processing module is used for respectively processing the characteristic hole position data, the first original data and the second original data to obtain a characteristic hole position on the skin to be assembled, a characteristic hole position on the skeleton, skeleton outer side surface type point clouds, an assembled skin outer side contour point set, a skin inner side surface type point cloud to be assembled and a skin outer side contour point set to be assembled;
the first hierarchical calculation module is used for calculating a pose solution set of the skin to be assembled under the condition that the pose solution set meets the external form precision in a preset tolerance threshold by combining an airplane digital model and utilizing the point cloud of the internal side surface of the skin to be assembled and the point cloud data of the external side surface of the skeleton;
the second-level calculation module is used for calculating a sub-solution set of the skin to be assembled meeting the skin butt joint clearance and the step tolerance in the preset tolerance threshold in the pose solution set by using the skin to be assembled outside contour point set data and the assembled skin outside contour point set data;
the third-level calculation module is used for calculating an optimal pose solution with characteristic holes which tend to align and assembly gaps which are infinitely close under the condition that the skin and the framework have no interference in the sub-solution set by utilizing the characteristic hole position data on the skin to be assembled and the characteristic hole position data on the framework and the inner side surface type point cloud and the outer side surface type point cloud data of the skin to be assembled; and
and the iteration expansion module is used for judging whether the optimal pose solution exists or not, if so, determining that the optimal pose solution is the actual pose adjustment amount, outputting the optimal pose solution to the skin pose adjustment positioner to perform a pose adjustment process, if not, expanding the preset tolerance threshold to expand the solution set range, continuously executing the first level calculation module, the second level calculation module and the third level calculation module, and continuously executing the iteration expansion module, the first level calculation module, the second level calculation module and the third level calculation module in an iteration mode to obtain an optimal pose solution.
8. The multi-constraint aircraft skin pose adjustment system according to claim 7, wherein the first hierarchy calculation module comprises:
the first matching unit is used for registering the skeleton outer side profile of the airplane digital model to the skeleton outer side profile point cloud;
the computing unit is used for computing the pose of the inner side of the skin to be assembled of the airplane digifax under an assembly coordinate system;
the expansion unit is used for enabling the surface shape precision of the inner side of the skin to be assembled to approximately represent the appearance precision of the airplane, and expanding the inner side of the skin to be assembled of the airplane digifax to a feasible space according to the preset tolerance threshold;
and the first searching unit is used for searching the actual skin pose of the inner side of the skin to be assembled, which is closest to the airplane digifax, in the feasible space to obtain the pose solution set.
9. The multi-constraint aircraft skin pose adjustment system according to claim 7, wherein the second-level calculation module comprises:
the second matching unit is used for registering the skin outer contour point set to be assembled to the skin outer contour point set to be assembled in the pose solution set range;
and the second searching unit is used for searching the pose closest to the assembled skin outer contour point set in the to-be-assembled skin outer contour point set to obtain the sub-solution set on the premise that the pose solution set range meets the requirements on gap and step difference.
10. The multi-constraint aircraft skin pose adjustment system according to claim 7, wherein the third level calculation module comprises:
and the third matching unit is used for performing data registration by using the positions of the feature holes on the skin to be assembled and the positions of the skeleton feature holes in the sub-solution set and combining the point cloud of the inner side surface of the skin to be assembled and the point cloud data of the outer side surface of the skeleton, and solving the optimal pose solution which is as close as possible and has as small as possible gaps in the sub-solution set range on the premise that the skin to be assembled and the skeleton do not interfere with each other.
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