CN118190339B - Method for measuring full-surface modal frequency vibration displacement of typical control surface model of aircraft - Google Patents
Method for measuring full-surface modal frequency vibration displacement of typical control surface model of aircraft Download PDFInfo
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Abstract
The invention provides a method for measuring the vibration displacement of a typical control surface model full-surface modal frequency of an aircraft, and belongs to the technical field of wind tunnel frequency vibration displacement measurement. S1, arranging speckle patterns and x-shaped mark points on the surface of a model, and uniformly arranging the mark points on the wall of a hole; s2, obtaining a shafting transformation matrix; s3, acquiring a reference image and a test image; s4, matching different camera visual angles and x-shaped mark points and mark point positions at different moments in the test process; s5, registering the X-shaped mark points of the base image and the test image to a common reference plane; s6, generating a triangle mesh; s7, quantifying displacement and deformation of the object under anisotropic stress; s8, calculating the offset of each speckle region grid; s9, analyzing the vibration characteristics of the specific speckle region. The invention solves the problem that the vibration displacement measurement of the modal frequency in a large range is difficult to realize, and the modal frequency of each position on the surface of the model can be obtained.
Description
Technical Field
The invention relates to a method for measuring the vibration displacement of a typical control surface model full-surface modal frequency of an aircraft, and belongs to the technical field of wind tunnel frequency vibration displacement measurement.
Background
The research on the modal frequency, the relative displacement of vibration and the appearance of the control surface of the aircraft under the high-speed condition is very important to ensure the flight safety and improve the flight performance. The modal characteristic analysis of the aircraft control surface can more accurately predict the dynamic response of the control surface under different flight speeds and environmental conditions. The method is beneficial to identifying possible resonance frequencies, avoiding structural fatigue and damage and ensuring the structural integrity and operation safety of the aircraft. In addition, the method for measuring and analyzing the modal characteristics in the wind tunnel test can provide direct information of the dynamic response of the structure under the actual flight condition. The method is helpful for verifying the results of ground test and theoretical calculation, ensuring the accuracy and reliability of the ground test and theoretical calculation, and disclosing the unique vibration problems such as flutter and the like which can occur under the action of high-speed air flow.
At present, structural modal frequency measurement is mainly carried out through knocking test. Vibration characteristics of an object are analyzed by tapping it and capturing the response using an accelerometer or sensor. The limitation of this method is that data can be acquired only at a limited number of points and is greatly affected by operator skill and test environment, and therefore, the method cannot be directly applied to wind tunnel tests, and the inconsistency and poor repeatability of results can be caused.
In addition, the laser Doppler vibration meter provides a non-contact and high-precision measurement mode, can cover a wider test area and provides more continuous and comprehensive data. However, it is susceptible to factors such as surface reflectance changes and light interference, which results in a decrease in measurement accuracy. Furthermore, the laser is focused at one or several points, so that it is difficult to achieve a large-scale or full-field measurement, limiting its application in the comprehensive analysis of complex vibration patterns.
In conclusion, the method for measuring the vibration displacement of the full-surface modal frequency of the typical control surface model of the aircraft, which is suitable for the high-speed wind tunnel, is developed, so that more comprehensive and accurate data can be provided, the requirements of aircraft design and performance verification are supported, and the data acquisition capacity and analysis precision of the high-speed wind tunnel test are improved.
Disclosure of Invention
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
In view of the above, the invention provides a method for measuring the modal frequency vibration displacement of a typical control surface model of an aircraft, which aims to solve the technical problem that the measurement of the modal frequency vibration displacement in a large range or in a whole field is difficult to realize in the prior art. The method is suitable for aircraft control surfaces of various materials and various shapes in a high-speed wind tunnel test, and can obtain the deformation of any position of the surface at any moment and the modal frequency of each position of the model surface in an actual test.
The method for measuring the full-surface modal frequency vibration displacement of the typical control surface model of the aircraft comprises the following steps:
S1, arranging speckle patterns and x-shaped mark points on the surface of a model, and uniformly arranging the mark points on the wall of a hole;
s2, solving internal and external parameters of the camera, and converting three-dimensional coordinates in a camera coordinate system into a wind tunnel coordinate system to obtain a shafting transformation matrix;
S3, collecting model images of different working conditions at the windless normal temperature, and taking the model images as reference images; in the process of acquisition test, a flow field steady state image is obtained and is used as a test image;
s4, matching different camera visual angles and x-shaped mark points and mark point positions at different moments in the test process;
s5, registering the X-shaped mark points of the base image and the test image to a common reference plane;
S6, dividing an external rectangle of the model speckle region into grids with equal intervals, drawing a mask to distinguish the model region from a non-model region in the external rectangle, and generating triangular grids;
s7, tracking speckle grids in a reference image and a test image which are shot from different view angles, and quantifying displacement and deformation of an object under anisotropic stress;
S8, carrying out inverse transformation and three-dimensional reconstruction on the speckle regions, recovering the matched speckle grids from the standard plane to the original curved surface by applying inverse polynomial transformation, and calculating the offset of each speckle region grid;
s9, analyzing the vibration characteristics of the specific speckle region.
Preferably, the method further includes performing optical noise suppression processing on the reference image after S3 is performed.
Preferably, the method further comprises repairing the vibration interference of the wall after the step S8 is executed, and the method comprises the following steps: and calculating the offset of the mark points on the wall of the hole, averaging, and differencing with the offset of each speckle region grid.
Preferably, the method for solving the internal and external parameters of the camera is as follows: obtaining camera internal and external parameter calibration, namely placing checkerboard calibration plates at different positions in a space where a model is positioned, shooting images of the checkerboard calibration plates, and solving the camera internal and external parameters based on a Zhang's calibration method; the size of the checkerboard calibration plate is determined according to the visual field range, and preferably, the checkerboard calibration plate occupies 1/5-1/3 of the visual field range; the internal parameters are; The external parameters are; Wherein the method comprises the steps ofThe focal length in the u, v direction,As a parameter of the radial distortion,Is the coordinates of the principal points;
Preferably, the method for converting the three-dimensional coordinates in the camera coordinate system into the wind tunnel coordinate system to obtain the shafting transformation matrix comprises the following steps: the attitude of the checkerboard calibration plate is adjusted to be 0 pitch, 0 yaw and 0 roll in the wind tunnel by a horizontal laser instrument and a high-precision inclinometer, at the moment, the x direction of the checkerboard calibration plate is parallel to the airflow direction, and the y direction is parallel to the vertical upward direction of the ground; calculating the difference of the three-dimensional coordinates of the angular points of the x direction of the checkerboard calibration plate, and normalizing to obtain a rolling axis vector Calculating the difference of three-dimensional coordinates of angular points in the y direction of the checkerboard calibration plate and carrying out normalization processing to obtain the yaw axial quantity; Based on rolling axis vectorsAxial amount of yaw axisAnd pitch axial amountRespectively vertical axes, and forms a coordinate system, defines the basic movement direction of the model in the wind tunnel space relative to the camera coordinate system, so that the three axial quantities are mutually orthogonal, and therefore, the pitching axial quantity is obtainedFinally, obtaining a shafting transformation matrix from the camera coordinate system to the wind tunnel coordinate system。
Preferably, the method for matching x-shaped mark points at different camera angles and different moments in the test process is as follows: selecting an image, manually determining x-shaped mark points, wherein the positions of the x-shaped mark points in the image areWherein m is the number of x-shaped mark points,The image coordinates of the 1 st x-shaped marker point,For the image coordinates of the ith x-shaped marker point,Image coordinates for the mth x-shaped marker point; for each x-shaped mark point and template radius r, a template region image is generated, i.e. toThe length of r is extended from the upper, lower, left and right as the center point to obtain a square template area I in the original image, and the template area I is used in other imagesFor the initial point, expanding the size of 3r up, down, left and right to obtain a square search area F, wherein each pixel point in the search area expands the square to-be-matched area with the size of r up, down, left and right，For the number of regions to be matched,For the k-th region to be matched,And calculating a normalized cross correlation value of each region and the template region I for the 1 st region to be matched, wherein the region to be matched with the template region I with the maximum normalized cross correlation value is considered to be the most matched region with the template region I, and the central point of the region is the matched x-shaped mark point position.
Preferably, the method of registering the fiducial image and trial image x-shaped marker points to a common reference plane is: constructing a point on each reference image and test imageCoordinates onto a standard planeIs a transformation matrix relation of (a):
；
wherein, Is the image coordinates of any point p on the reference image or test image,The coordinates of the p point on a standard plane; a-f are transformation coefficients to be solved, each x-shaped mark point constructs a transformation matrix relation, all matrixes are arranged into an equation set, and the transformation coefficients are obtained based on the least square method.
Preferably, the method of analyzing the vibration characteristics of a specific speckle region is: the method comprises the steps of subtracting the mean value of deformation in a time domain from the deformation of a speckle region in the time domain, removing direct current components of signals, normalizing the signals, converting deformation data into frequency domain information by adopting fast Fourier transform, drawing an amplitude chart by taking the actual frequency of each frequency point as an x-axis and the amplitude information of each frequency point as a y-axis, and observing the frequency information of vibration of a control surface.
The second scheme is an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor realizes the step of the full surface modal frequency vibration displacement measurement method of the typical control surface model of the aircraft when executing the computer program.
A third aspect is a computer readable storage medium, on which a computer program is stored, where the computer program when executed by a processor implements the method for measuring a full-surface mode frequency vibration displacement of a typical rudder surface model of an aircraft according to the first aspect.
The beneficial effects of the invention are as follows: the invention effectively extracts the frequency domain information from the time domain signal and reveals the vibration mode characteristics of the model. The method is favorable for completing verification and analysis of the model characteristics of the control surface of the aircraft, is suitable for measuring the full-surface model characteristics of various control surfaces of the aircraft in a high-speed wind tunnel, is not influenced by a model and environment, and has universal applicability. The invention solves the technical problem that the large-range or full-field modal frequency vibration displacement measurement is difficult to realize in the prior art, and can obtain the deformation of any position of the surface at any moment and the modal frequency of each position of the model surface in the actual test.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
FIG. 1 is a flow chart of a method for measuring the vibration displacement of a typical control surface model full-surface modal frequency of an aircraft;
FIG. 2 is a schematic view of an circumscribed rectangle;
FIG. 3 is a block diagram of a typical control surface model full surface modal frequency vibration displacement measurement device for an aircraft;
Fig. 4 is a diagram of a wind tunnel coordinate system calibration device.
Detailed Description
In order to make the technical solutions and advantages of the embodiments of the present invention more apparent, the following detailed description of exemplary embodiments of the present invention is provided in conjunction with the accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention and not exhaustive of all embodiments. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
Example 1: 1-2, the method for measuring the full-surface modal frequency vibration displacement of the typical control surface model of the aircraft comprises the following steps:
S1, arranging speckle patterns and x-shaped mark points on the surface of a model, uniformly arranging the mark points on the wall of a hole, and mounting cameras on the side wall of a wind tunnel;
The speckle pattern is arranged: wiping floating ash on the surface of the model by using dust-free paper, spraying white paint on the surface of the model uniformly by using a matte white hand, pasting the sticker printed with the speckle pattern on the white primer after the white paint is air-dried, flattening the sticker by using soft matters such as adhesive tape, reducing bubbles and wrinkles, and ensuring the flatness and stability of the sticker;
Arranging x-shaped mark points: uniformly arranging x-shaped marks outside each strip of the model by using a black marker, wherein 3-4 marks are arranged on each strip of the edge; uniformly arranging 3-6 marks in the shape of x on the surface of the model;
Arranging marking points: and uniformly arranging 10 mark points which are not blocked by the model on the wall of the hole.
The method for installing the camera on the side wall of the wind tunnel comprises the following steps: a permanent magnet jack 5, a guide rail 6 and a spanner sliding block 4 are used for constructing a stable bracket on the side wall of a wind tunnel, two high-speed cameras 1 are installed on the bracket, and the high-speed cameras 1 are symmetrically installed on the same horizontal plane to keep a fixed included angle. The two high-speed cameras 1 keep synchronism through the synchronous signal generator 2, the aperture of the high-speed cameras 1 is adjusted, enough depth of field is ensured, and the focal lengths of the high-speed cameras 1 are respectively adjusted so that the high-speed cameras 1 can clearly shoot the measuring area and the marked points on the wall of the hole.
A light source may be installed near the high-speed camera 1 in order to improve photographing accuracy of the high-speed camera 1;
s2, solving internal and external parameters of the camera, and converting three-dimensional coordinates in a camera coordinate system into a wind tunnel coordinate system to obtain a shafting transformation matrix;
the method for solving the internal and external parameters of the camera is as follows: obtaining camera internal and external parameter calibration, namely placing checkerboard calibration plates at different positions in a space where a model is located, shooting images of the checkerboard calibration plates, and solving the camera internal and external parameters based on a Zhang's calibration method; the size of the checkerboard calibration plate is determined according to the visual field range, and preferably, the checkerboard calibration plate occupies 1/5-1/3 of the visual field; the internal parameters are ; The external parameters are; Wherein the method comprises the steps ofThe focal length in the u, v direction,As a parameter of the radial distortion,Is the coordinates of the principal points;
The method for converting the three-dimensional coordinates in the camera coordinate system into the wind tunnel coordinate system to obtain the shafting transformation matrix comprises the following steps: the posture of the checkerboard calibration plate 9 is adjusted to be 0 pitch, 0 yaw and 0 roll in the wind tunnel by the horizontal laser instrument 8 and the high-precision inclinometer 11, at the moment, the x direction of the checkerboard calibration plate 9 is parallel to the airflow direction, and the y direction is parallel to the vertical upward direction of the ground; the rolling axis vector is obtained by calculating the difference of the three-dimensional coordinates of the angular points of the 9x direction of the checkerboard calibration plate and normalizing Calculating the difference of three-dimensional coordinates of angular points in the y direction of the checkerboard calibration plate 9y, and normalizing to obtain the yaw axial quantity; Based on rolling axis vectorsAxial amount of yaw axisAnd pitch axial amountRespectively vertical axes and forms a coordinate system, and defines the basic movement direction of the model in the wind tunnel space relative to the camera coordinate system, so that these three axial quantities must be mutually orthogonal, and based on this theory, the pitch axis vector can be obtained，（Representing cross multiplication) and finally obtaining an shafting transformation matrix from the camera coordinate system to the wind tunnel coordinate system。
S3, collecting model images of different working conditions at the windless normal temperature, and taking the model images as reference images; in the process of acquisition test, a flow field steady state image is obtained and is used as a test image; in the test process, the test angle state is reached first, and then the flow field stable state is reached; the number of images acquired under each working condition is at least 10;
s4, matching different camera visual angles and x-shaped mark points and mark point positions at different moments in the test process;
The method for matching the X-shaped mark points at different camera visual angles and different moments in the test process is as follows: selecting an image, manually determining x-shaped mark points, wherein the positions of the x-shaped mark points in the image are Wherein m is the number of x-shaped mark points,The image coordinates of the 1 st x-shaped marker point,For the image coordinates of the ith x-shaped marker point,Image coordinates for the mth x-shaped marker point; for each x-shaped mark point and template radius r, a template region image is generated, i.e. toThe length of r is extended from the upper, lower, left and right as the center point to obtain a square template area I in the original image, and the template area I is used in other imagesFor the initial point, expanding the size of 3r up, down, left and right to obtain a square search area F, wherein each pixel point in the search area expands the square to-be-matched area with the size of r up, down, left and right，For the number of regions to be matched,For the k-th region to be matched,And calculating normalized cross correlation values of each region to be matched and the template region I for the 1 st region to be matched, wherein the region to be matched with the largest normalized cross correlation value is considered to be the region which is most matched with the square template region I, and the central point of the region is the position of the matched x-shaped mark point.
S5, registering the X-shaped mark points of the base image and the test image to a common reference plane;
Registering the images of different view angles and the images of different moments to a common reference plane in an affine transformation mode based on the positions of the x-shaped mark points so as to eliminate distortion caused by the inclination of the angles of the camera;
constructing a transformation matrix relation of coordinates from points on each reference image and each test image to points on a standard plane:
；
wherein, Is the image coordinates of any point p on the reference image or test image,The coordinates of the p point on a standard plane; a-f are transformation coefficients to be solved, each x-shaped mark point constructs a transformation matrix relation, all matrixes are arranged into an equation set, and the transformation coefficients are obtained based on the least square method.
S6, dividing an external rectangle of the model speckle region into equidistant grids, drawing a mask to distinguish a model region from a non-model region in the external rectangle, and generating triangular grids, wherein the method comprises the following steps of: manually selecting boundary points of the model, and obtaining an external rectangle according to coordinate information of the selected boundary points, wherein the external rectangle is defined as (xmin: xmax, ymin: ymax) by referring to a minimum value xmin of x-direction coordinates, a maximum value xmax of y-direction coordinates, a minimum value ymin of y-direction coordinates and a maximum value ymax of y-direction coordinates in the boundary points shown in FIG. 2;
The method for generating the triangular mesh comprises the steps of generating the triangular mesh by using a mesh center point and adopting a Delaunay triangulation algorithm;
Optimizing a triangle mesh: removing incorrect grids, optimizing grid layout, and specifically adding logic judgment: setting an unreliable angle and an unreliable longest side, and deleting the grid when one side length of the constructed grid is greater than or equal to the unreliable longest side or any included angle is greater than or equal to the unreliable angle.
S7, tracking speckle grids in a reference image and a test image which are shot from different view angles, and quantifying displacement and deformation of an object under anisotropic stress;
The speckle region is matched, and the speckle grids are tracked from a reference image and a test image which are shot from different view angles by utilizing an ADIC2D algorithm so as to quantify the displacement and deformation of an object under anisotropic stress, specifically comprising the following steps: setting a circular subset shape in an ADIC2D algorithm, wherein radial symmetric distribution is more beneficial to accurate matching of a speckle region, and describing the displacement of pixel points in the speckle region through a shape function; the shape function parameters are iteratively optimized to minimize the difference between the reference image and the target image to accomplish a more accurate match to the speckle region.
S8, carrying out inverse transformation and three-dimensional reconstruction on the speckle regions, recovering the matched speckle grids from the standard plane to the original curved surface by applying inverse polynomial transformation, and calculating the offset of each speckle region grid;
the specific method comprises the following steps: after S7, matching speckle grids of the reference image under two view angles, and according to the coordinates of the center point of the matched speckle grids in the image Combining the internal and external parameters of the camera to obtain the three-dimensional coordinates of all speckle regions in the reference state (without wind) under the central camera coordinate systemFormula (VI)In the process of transforming matrix through shaftingAccording to the formulaObtaining the three-dimensional coordinates of the central point of the speckle region in the reference state under the wind tunnel coordinate systemThe three-dimensional coordinates of the central point of the speckle region matched with the speckle region under the test state (in the presence of wind) are obtained by the same methodWindoff denotes a reference state (windless), wind denotes a test state (windy), and the shift amount of each speckle region grid is。
S9, analyzing vibration characteristics of a specific speckle region, subtracting the mean value of deformation of the speckle region in a time domain from the deformation of the speckle region in the time domain, removing direct current components of signals, carrying out normalization processing on the signals, and converting deformation data into frequency domain information by adopting Fast Fourier Transform (FFT);
；
wherein, In order to deform the data,Is frequency domain information, N is the number of data points, and k is the frequency domain index (whose value is 0 to N-1).
The modal spectrum information can be observed from the amplitude spectrum, in particular the amplitude of each frequency component k is calculated=WhereinIs a complex numberIs used for the real part of (c),Is a complex numberIs provided with the imaginary part ofFor the sampling frequency, according to the sum of the sampling frequenciesCalculating the actual frequency of each frequency point k as。
Then according to the abscissaAnd the ordinateThe amplitude diagram can be drawn, and the main frequency component of the control surface vibration, namely the modal frequency information, is observed.
The invention also comprises the steps of processing the reference image and the test image after executing S3, and performing optical noise suppression processing on the reference image, wherein the method comprises the following steps: and (3) carrying out stack average operation on the multiple reference images under each working condition, namely reducing the influence of random noise by averaging the multiple samples and inhibiting optical noise.
The invention also comprises the following steps of: calculating the offset of the marked points on the wall of the tunnel, particularly collecting a group of images in the absence of wind, and calculating the three-dimensional coordinate set of the marked points in the imagesWindoff shows no wind condition, t is the number of marked points, and three-dimensional coordinate sets are calculated for the marked points of each frame of image during testWhen wind represents wind, the difference value of all mark points is calculated and averaged to obtain the interference quantity of the tunnel wall; The calculated offset of each speckle region grid is then subtractedAnd the interference repair of the vibration of the tunnel wall is realized.
Example 2: referring to fig. 3, the embodiment is described, and an aircraft typical control surface model full-surface modal frequency vibration displacement measuring device comprises a high-speed camera 1, a synchronous signal generator 2, a light source 3, a wrench sliding block 4, a permanent magnet jack 5, a guide rail 6 and a computer device 7;
the permanent magnet jack 5 and the guide rail 6 are connected to form a fixed bracket;
The high-speed camera 1 is fixed on a fixed bracket formed by the permanent magnet jack 5 and the guide rail 6 through the wrench sliding block 4, and the high-speed camera 1 is symmetrically arranged on the same horizontal plane and keeps a fixed included angle;
The light source 3 is fixed on a fixed bracket formed by the permanent magnet jack 5 and the guide rail 6 through the wrench sliding block 4, so as to illuminate a test area;
The permanent magnet jack 5 is adsorbed on the wind tunnel side wall plate;
The synchronous signal generator 2 is connected with the high-speed camera 1, and sends a trigger signal through the computer device 7 so as to trigger the high-speed camera 1 to collect test images;
Computer means 7 connected to the high-speed camera 1 and the synchronization signal generator 2 for generating trigger signals, storing images, and data processing;
example 3: referring to fig. 4, the embodiment is described, and a wind tunnel coordinate system calibration device comprises a horizontal laser 8, a checkerboard calibration plate 9, a pitching and rolling adjustment bracket 10 and a high-precision inclinometer 11;
The horizontal laser instrument 8 is arranged in the wind tunnel, and the position of the horizontal laser instrument 8 is adjusted so that a laser signal emitted by the horizontal laser instrument 8 is radiated on the horizontal plane of the wind tunnel strut, and the plane of the laser signal is parallel to a plane formed by the wind speed flow direction and the lateral direction; the checkerboard calibration plate 9 is arranged on the pitching and rolling adjustment bracket 10, and a horizontal table is arranged at the top of the checkerboard calibration plate 9 and is used for placing the high-precision inclinometer 11;
Adjusting the positions of the checkerboard calibration plates 9 until the planes of the checkerboard calibration plates 9 are parallel to the plane of the horizontal laser instrument 8;
the pitching and rolling adjusting bracket 10 is used for adjusting the pitch angle and the rolling angle of the checkerboard calibration plate 9 under the wind tunnel coordinate system, and judging whether the current angle is 0 or not through the high-precision inclinometer 11;
the high-precision inclinometer 11 checks whether the rolling angle and the pitch angle of the checkerboard calibration plate 9 in the wind tunnel coordinate system are 0.
Example 4: the electronic device of the present invention may be a device including a processor and a memory, such as a single chip microcomputer including a central processing unit. And the processor is used for realizing the steps of the method for measuring the full-surface modal frequency vibration displacement of the typical control surface model of the aircraft when executing the computer program stored in the memory.
The Processor may be a central processing unit (Central Processing Unit, CPU), other general purpose Processor, digital signal Processor (DIGITAL SIGNAL Processor, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), off-the-shelf Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data (such as audio data, phonebook, etc.) created according to the use of the handset, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, memory, plug-in hard disk, smart memory card (SMART MEDIA CARD, SMC), secure Digital (SD) card, flash memory card (FLASH CARD), at least one disk storage device, flash memory device, or other volatile solid-state storage device.
Example 5: computer-readable storage medium embodiments.
The computer readable storage medium of the present invention may be any form of storage medium readable by a processor of a computer device, including but not limited to non-volatile memory, ferroelectric memory, etc., on which a computer program is stored, which when read and executed by the processor of the computer device, can implement the steps of the above-described method for measuring full surface mode frequency vibration displacement of an aircraft typical control surface model.
The computer program comprises computer program code which may be in source code form, object code form, executable file or in some intermediate form, etc. The computer readable storage medium may include: any entity or device capable of carrying the computer program code, a recording medium, a U disk, a removable hard disk, a magnetic disk, an optical disk, a computer Memory, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), an electrical carrier signal, a telecommunications signal, a software distribution medium, and so forth. It should be noted that the computer readable storage medium may include content that is subject to appropriate increases and decreases as required by jurisdictions and by jurisdictions in which such computer readable storage medium does not include electrical carrier signals and telecommunications signals.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of the above description, will appreciate that other embodiments are contemplated within the scope of the invention as described herein. Furthermore, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is defined by the appended claims.
Claims (10)
1. The method for measuring the vibration displacement of the full-surface modal frequency of the typical control surface model of the aircraft is characterized by comprising the following steps of:
S1, arranging speckle patterns and x-shaped mark points on the surface of a model, and uniformly arranging the mark points on the wall of a hole;
s2, solving internal and external parameters of the camera, and converting three-dimensional coordinates in a camera coordinate system into a wind tunnel coordinate system to obtain a shafting transformation matrix;
S3, collecting model images of different working conditions at the windless normal temperature, and taking the model images as reference images; in the process of acquisition test, a flow field steady state image is obtained and is used as a test image;
s4, matching different camera visual angles and x-shaped mark points and mark point positions at different moments in the test process;
s5, registering the X-shaped mark points of the base image and the test image to a common reference plane;
S6, dividing an external rectangle of the model speckle region into grids with equal intervals, drawing a mask to distinguish the model region from a non-model region in the external rectangle, and generating triangular grids;
s7, tracking speckle grids in a reference image and a test image which are shot from different view angles, and quantifying displacement and deformation of an object under anisotropic stress;
S8, carrying out inverse transformation and three-dimensional reconstruction on the speckle regions, recovering the matched speckle grids from the standard plane to the original curved surface by applying inverse polynomial transformation, and calculating the offset of each speckle region grid;
s9, analyzing the vibration characteristics of the specific speckle region.
2. The method for measuring the vibration displacement of the full surface mode frequency of the typical control surface model of the aircraft according to claim 1, further comprising the step of performing the optical noise suppression processing on the reference image after performing S3.
3. The method for measuring the vibration displacement of the full surface mode frequency of the typical control surface model of the aircraft according to claim 1, further comprising the following steps of: and calculating the offset of the mark points on the wall of the hole, averaging, and differencing with the offset of each speckle region grid.
4. The method for measuring the vibration displacement of the full surface modal frequency of the typical control surface model of the aircraft according to claim 1, wherein the method for solving the internal and external parameters of the camera is as follows: obtaining camera internal and external parameter calibration, namely placing checkerboard calibration plates at different positions in a space where a model is positioned, shooting images of the checkerboard calibration plates, and solving the camera internal and external parameters based on a Zhang's calibration method; the size of the checkerboard calibration plate is determined according to the visual field range, and the checkerboard calibration plate occupies 1/5-1/3 of the visual field range; the internal parameters are; The external parameters are; Wherein the method comprises the steps ofThe focal length in the u, v direction,As a parameter of the radial distortion,Is like principal point coordinates.
5. The method for measuring the vibration displacement of the full-surface modal frequency of the typical control surface model of the aircraft according to claim 1, wherein the method for converting the three-dimensional coordinates in the camera coordinate system into the wind tunnel coordinate system to obtain the transformation matrix is as follows: the posture of the checkerboard calibration plate (9) is adjusted to be 0 pitch, 0 yaw and 0 roll in the wind tunnel by the horizontal laser instrument (8) and the high-precision inclinometer (11), at the moment, the x direction of the checkerboard calibration plate (9) is parallel to the airflow direction, and the y direction is parallel to the vertical upward direction of the ground; the rolling axis vector is obtained by calculating the difference of the three-dimensional coordinates of the angular points of the x direction of the checkerboard calibration plate (9) and normalizingCalculating the difference of three-dimensional coordinates of angular points in the y direction of the checkerboard calibration plate (9) and carrying out normalization treatment to obtain the yaw axial quantity; Based on rolling axis vectorsAxial amount of yaw axisAnd pitch axial amountRespectively vertical axes, and forms a coordinate system, defines the basic movement direction of the model in the wind tunnel space relative to the camera coordinate system, so that the three axial quantities are mutually orthogonal, and therefore, the pitching axial quantity is obtainedFinally, obtaining a shafting transformation matrix from the camera coordinate system to the wind tunnel coordinate system。
6. The method for measuring the vibration displacement of the full-surface modal frequency of the typical control surface model of the aircraft according to claim 1, wherein the method for matching the different camera viewing angles and the x-shaped mark points at different moments in the test process is as follows: selecting an image, manually determining x-shaped mark points, wherein the positions of the x-shaped mark points in the image areWherein m is the number of x-shaped mark points,The image coordinates of the 1 st x-shaped marker point,For the image coordinates of the ith x-shaped marker point,Image coordinates for the mth x-shaped marker point; for each x-shaped mark point and template radius r, a template region image is generated, i.e. toThe length of r is extended from the upper, lower, left and right as the center point to obtain a square template area I in the original image, and the template area I is used in other imagesFor the initial point, expanding the size of 3r up, down, left and right to obtain a square search area F, wherein each pixel point in the search area expands the square to-be-matched area with the size of r up, down, left and right，For the number of regions to be matched,For the k-th region to be matched,And calculating normalized cross correlation values of each region to be matched and the template region I for the 1 st region to be matched, wherein the region to be matched with the template region I with the largest normalized cross correlation value is considered as the region which is matched with the template region I, and the central point of the region is the position of the matched x-shaped mark point.
7. The method for measuring the vibration displacement of the full surface mode frequency of the typical control surface model of the aircraft according to claim 1, wherein the method for registering the x-shaped mark points of the reference image and the test image to a common reference plane is as follows: constructing a point on each reference image and test imageCoordinates onto a standard planeIs a transformation matrix relation of (a):
；
wherein, Is the image coordinates of any point p on the reference image or test image,The coordinates of the p point on a standard plane; a-f are transformation coefficients to be solved, each x-shaped mark point constructs a transformation matrix relation, all matrixes are arranged into an equation set, and the transformation coefficients are obtained based on the least square method.
8. The method for measuring the vibration displacement of the full surface mode frequency of the typical control surface model of the aircraft according to claim 1, wherein the method for analyzing the vibration characteristics of the specific speckle region is as follows: the method comprises the steps of subtracting the mean value of deformation in a time domain from the deformation of a speckle region in the time domain, removing direct current components of signals, normalizing the signals, converting deformation data into frequency domain information by adopting fast Fourier transform, drawing an amplitude chart by taking the actual frequency of each frequency point as an x-axis and the amplitude information of each frequency point as a y-axis, and observing the frequency information of vibration of a control surface.
9. An electronic device comprising a memory and a processor, the memory storing a computer program, the processor implementing the steps of the method for measuring full surface mode frequency vibration displacement of a typical rudder surface model of an aircraft according to any one of claims 1 to 8 when the computer program is executed.
10. A computer-readable storage medium, characterized in that it has stored thereon a computer program which, when executed by a processor, implements a method for measuring the vibration displacement of a model full surface mode frequency of a typical control surface of an aircraft according to any one of claims 1 to 8.
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| CN115979567A (en) * | 2022-08-03 | 2023-04-18 | 中国航天空气动力技术研究院 | Real-time deformation measurement method for wind tunnel aeroelasticity test of elastic wing |
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| CN114413788A (en) * | 2022-01-21 | 2022-04-29 | 武汉惟景三维科技有限公司 | Part surface pattern detection method based on binocular vision and reverse model reconstruction |
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