CN107167235B - Device and method for vibration detection of hinged honeycomb panel based on digital image correlation algorithm - Google Patents

Abstract

The invention discloses a vibration detection device and method for a hinged honeycomb panel based on a digital image correlation algorithm. The device includes a hinged honeycomb panel body, a spotter, an industrial camera, a vibrator and a computer. Composed of two honeycomb sandwich panels, every two honeycomb sandwich panels are connected by a hinge between the panels. One end of the hinged honeycomb panel body is mechanically connected to the metal support by a splint and a steel frame, and the other end is a free end; The light source provides a feature area that can be tracked and monitored for the binocular vision system, and the industrial camera extracts and collects the three-dimensional coordinate information of the honeycomb panel body. The method of digital image correlation is used to detect the vibration of the honeycomb panel body, so that the measurement system has high precision, little interference to the measured object, and can realize full-field measurement. In addition, the device can also be used to simulate and study the vibration characteristics of solar panels.

Description

Device and method for vibration detection of hinged honeycomb panel based on digital image correlation algorithm

technical field

The invention relates to the field of positioning and vibration detection of flexible structures, in particular to a vibration detection device and method for a hinged honeycomb panel based on a digital image correlation algorithm.

Background technique

After the spacecraft enters the target orbit, the solar panels are unfolded, and the hinges between the panels are in a locked state. At this time, the positional relationship between the two panels is fixed, and the solar panels can be approximately regarded as thin rectangular panels. Large in size, low in stiffness, and high in flexibility, it will produce strong and continuous vibrations when subjected to external disturbances, which may lead to instability of the spacecraft or satellite body. Therefore, the research on the vibration characteristics of solar panels is of great significance.

Carbon fiber and aluminum honeycomb composite materials are widely used in spacecraft cabin structure, equipment support, solar wing substrate, etc. due to their excellent properties such as high specific strength, high specific stiffness, light weight, heat insulation and vibration resistance, and designable thermal expansion coefficient. . The composite honeycomb sandwich structure is composed of three basic materials, including the upper and lower panels, the core layer and the adhesive between the core layer and the panel. The upper and lower surfaces are composed of thin panels to provide bending stiffness, plane tension and compression, and shear. Stiffness; the middle honeycomb core is thicker and has a low density, which separates the upper and lower panels and provides a transmission path for the transverse shear stress flow; the adhesive layer connects the honeycomb core and the panel to facilitate load transfer.

In the research of vibration measurement and active control of large flexible structures, using binocular vision system to measure the vibration of structures has its unique advantages. Binocular vision measurement is a non-contact measurement, which does not change the vibration characteristics of the structure, so the measurement results obtained are more accurate. The digital image correlation method is to determine the vibration information of the object according to the statistical correlation of the light spot field randomly distributed on the surface of the object before and after vibration. This method has the advantages of real-time, non-contact, high precision, panoramic measurement, and little interference to the measured object. . The traditional two-dimensional digital image correlation method can only measure two-dimensional displacement and strain, but the three-dimensional displacement measurement of objects can be realized based on the principle of binocular stereo vision and digital image correlation method.

Contents of the invention

The object of the present invention is to provide a vibration detection device for hinged honeycomb panels based on digital image correlation algorithm to realize the non-contact, real-time and accurate measurement of the vibration of the hinged honeycomb panel body in view of the shortcomings and deficiencies of the prior art.

Another object of the present invention is to provide a vibration detection method for hinged honeycomb panels based on a digital image correlation algorithm.

The purpose of the present invention can be achieved through the following technical solutions:

A vibration detection device for a hinged honeycomb panel based on a digital image correlation algorithm, including a hinged honeycomb panel body part, a projection measurement part, a vibration excitation part and a computer, the hinged honeycomb panel body part includes three pieces of honeycomb core with the same size The panels are respectively the first honeycomb sandwich panel, the second honeycomb sandwich panel and the third honeycomb sandwich panel, and every two honeycomb sandwich panels are connected together by two inter-panel hinges at symmetrical positions up and down to form a The end of the first honeycomb sandwich panel of the hinged honeycomb panel body is mechanically connected to the metal support through the splint and the steel frame, and the metal support is vertically fixed on the horizontal experimental platform, and the other end of the hinged honeycomb panel body is a free end, and The hinged honeycomb panel body is perpendicular to the horizontal plane of the experimental pedestal; the projection measurement part includes a point thrower and two industrial cameras, both of which are fixed on the tripod, and the mirror surface of the point thrower is facing the hinged honeycomb On the surface of the board body, two industrial cameras are respectively installed on both sides of the dot shooter to ensure that its field of view fully covers the second honeycomb sandwich panel and the third honeycomb sandwich panel; the vibration excitation part includes three of the same type The exciter and the supporting high-voltage amplifier, the three exciters are evenly distributed in the width direction of the first honeycomb sandwich panel close to the metal support, the positions of the upper and lower two exciters are symmetrical about the midline of the width direction, and the position of the middle position The vibrator is located on the centerline in the width direction.

Further, the honeycomb sandwich panel is composed of a honeycomb core, an adhesive layer and a panel, and the adhesive layer bonds the upper and lower panels and the honeycomb core into an integral rigid structure.

Further, the inter-panel hinge is composed of a male hinge, a female hinge, a coil spring, a pin shaft, a locking swing lever and an eccentric screw. The pin shafts rotate relative to each other. During the rotation process, the pin on the locking swing bar first slides along the unfolding slideway on the male hinge, and at the end of the unfolding process, slides in along the left side of the locking groove on the male hinge and finally gets stuck on it. Lock the bottom of the groove; in the locked state, the positional relationship between the honeycomb sandwich panels is fixed, and the hinged honeycomb panel body is fully unfolded. In this state, the hinged honeycomb panel body can be regarded as a whole rectangular panel.

Further, the vibration detection device of the hinged honeycomb panel based on the digital image correlation algorithm can be used to simulate and study the vibration characteristics of the main body of the solar sail panel after it is deployed.

Another object of the present invention can be achieved through the following technical solutions:

A method for detecting the vibration of a hinged honeycomb panel based on a digital image correlation algorithm, said method comprising the following steps:

Step 1. The vibration excitation signal sent by the computer is transferred to the high-voltage amplifier after A/D conversion. The signal is amplified by the high-voltage amplifier and then transmitted to the three exciters. The exciters excite the hinged honeycomb panel body to bend or bend according to different combinations of signals. torsional vibration;

Step 2. Turn on the dot projector and evenly project the light spot onto the surface of the second honeycomb sandwich panel and the third honeycomb sandwich panel to form a spot field with continuous characteristic areas. Use the binocular vision measurement system composed of two industrial cameras to measure the The vibration body of the hinged honeycomb panel collects continuous images, divides and selects the characteristic sub-regions of interest on the image, runs the corresponding digital image correlation algorithm, obtains the three-dimensional coordinate information of the region of interest, and indirectly obtains the vibration information of the hinged honeycomb panel body ;

Step 3. By changing the form, frequency, and amplitude parameters of the excitation signal, repeated experiments, and obtaining multiple experimental results, the vibration characteristics of the hinged honeycomb panel body are obtained.

Further, in step 1, by transmitting excitation signals of the same frequency and phase to the three exciters, the bending vibration of the hinged honeycomb panel body can be excited; The signal can excite the torsional vibration of the hinged honeycomb panel body.

Further, in step 2, divide and select the characteristic sub-region of interest on the collected continuous images as the reference position for vibration detection, and analyze the statistics of the position before and after the vibration by matching the images containing the sub-region before and after the vibration. Correlation is used to determine and extract the vibration displacement information of the hinged honeycomb panel vibration body. By changing the number of regions of interest and their positions on the hinged honeycomb panel vibration body, the detection process can simultaneously collect the different parts of the hinged honeycomb panel body. The vibration information can be used to measure the multi-mode coupling vibration of the hinged honeycomb panel to realize the decoupling of vibration.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The present invention utilizes the method of projecting marker points combined with camera detection. On the one hand, it can realize the complete non-contact measurement of the vibration of the hinged honeycomb panel, and the measurement results have higher accuracy; on the other hand, compared with the vibration The surface of the main body is coated with spots, and the method of projecting light spots is efficient and easy, and the projected light spots have regular shapes and good suppression, which can fully simplify the subsequent image analysis and processing operations, and provide a good solution for digital image-related vibration detection methods. Foundation.

2. The hinged honeycomb plate vibration detection device based on the digital image correlation algorithm of the present invention can be used to study the influence of the nonlinear characteristics of the hinge joint on the vibration system. Due to the existence of friction and other nonlinear factors in the joints of the hinge parts between the plates, It will affect the vibration of the hinged honeycomb panel. In this device, the vibration of the second hinged honeycomb panel and the third hinged honeycomb panel are detected at the same time. The collected data can be used to study the dynamic characteristics of the hinge itself. This device simulates the vibration of the solar panel under the influence of the nonlinear characteristics of the hinge, which provides a good foundation for in-depth study of its vibration characteristics.

3. The vibration detection device of the present invention adopts a hinged honeycomb panel and a pivot-pin hinge structure to simulate the solar sail panel structure, which can more truly restore its vibration in space, and the vibration characteristics obtained through measurement and analysis are also useful for spacecraft. The design and manufacture of the solar panel structure are instructive.

4. The present invention uses a digital image correlation method to carry out vibration detection on the experimental object. During image processing and analysis, the vibration information is extracted according to the statistical characteristics of the region of interest. Compared with the traditional information extraction of a single marker point, the method utilizes More image information is obtained, which makes the vibration signal obtained by measurement more accurate.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a vibration detection device for hinged honeycomb panels based on a digital image correlation algorithm according to Embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of the inter-panel hinge in Embodiment 1 of the present invention.

Fig. 3 is a schematic structural diagram of a honeycomb sandwich panel in Example 1 of the present invention.

FIG. 4 is a schematic diagram of a spot field formed by projection points in Embodiment 2 of the present invention.

Fig. 5 is a schematic diagram of the principles of sub-region images before and after vibration matching by the digital image correlation algorithm according to Embodiment 2 of the present invention.

Among them, 1-tripod, 2-industrial camera, 3-pointer, 4-third honeycomb sandwich panel (4-1-honeycomb core, 4-2-adhesive layer, 4-3-panel), 5 -Hinge between plates (5-1-male hinge, 5-2-coil spring, 5-3-slide, 5-4-female hinge, 5-5-eccentric screw, 5-6-pin, 5-7 -Lock swing bar, 5-8-column pin), 6-second honeycomb sandwich panel, 7-first honeycomb sandwich panel, 8-vibrator, 9-steel frame, 10-metal support, 11- Experimental pedestal, 12-high voltage amplifier, 13-computer.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1:

As shown in Fig. 1, the present embodiment provides a kind of hinged honeycomb panel vibration detection device based on digital image correlation algorithm, comprising hinged honeycomb panel body part, projection measurement part, vibration excitation part and computer (13), described hinged honeycomb panel The panel body part includes three honeycomb sandwich panels of the same material and size, which are respectively the first honeycomb sandwich panel (7), the second honeycomb sandwich panel (6) and the third honeycomb sandwich panel (4). The two honeycomb sandwich panels are connected together by two inter-panel hinges (5) at the upper and lower symmetrical positions, and the first honeycomb sandwich panel end of the hinged honeycomb panel body is mechanically connected to the metal via the splint and the steel frame (9). On the support (10), the metal support (10) is vertically fixed on the horizontal experimental platform (11), the other end of the hinged honeycomb panel body is a free end, and the horizontal plane of the hinged honeycomb panel body and the experimental platform (11) Vertical; the projection measurement part includes a point thrower (3) and two industrial cameras (2), and the point thrower (3) and two industrial cameras (2) are all fixed on the tripod (1), and the point thrower The mirror surface of (3) is facing the surface of the hinged honeycomb panel body, and two industrial cameras (2) are respectively installed on both sides of the point shooter (3) to ensure that its field of view fully includes the second honeycomb sandwich panel (6) and The third honeycomb sandwich panel (4); the vibration excitation part includes three exciters (8) of the same type and a supporting high-voltage amplifier (12), and the three exciters (8) are evenly distributed on the first In the width direction of the honeycomb sandwich panel (7) close to the metal support (10), the positions of the upper and lower two exciters (8) are symmetrical about the center line in the width direction, and the exciter (8) in the middle position is located on the center line in the width direction .

The structural diagram of the honeycomb sandwich panel is as shown in Figure 3, and is made up of honeycomb core (4-1), adhesive layer (4-2) and panel (4-3), and adhesive layer (4-2) will The upper and lower panels (4-3) are cemented with the honeycomb core (4-1) to form an integral rigid structure. The structural diagram of the inter-plate hinge (5) is shown in Figure 2, consisting of a male hinge (5-1), a female hinge (5-4), a coil spring (5-2), pin shafts (5-6), The lock pendulum (5-7) and the eccentric screw (5-5) are composed, and when the inter-plate hinge (5) is unfolded, the male hinge (5-1) and the female hinge (5-4) are in the drive element coil spring (5 -2) under the action of relative rotation around the pin shaft (5-6), in the process of rotation, the pin (5-8) on the lock pendulum (5-7) is first along the pin on the male hinge (5-1). The unfolding slideway (5-3) slides, slides in along the left side of the locking groove on the male hinge (5-1) at the end of the unfolding process and finally gets stuck at the bottom of the locking groove; in the locked state, the honeycomb sandwich core The positional relationship between the panels is fixed, and the hinged honeycomb panel body is fully unfolded. In this state, the hinged honeycomb panel body can be regarded as a whole rectangular panel.

The hinged honeycomb panel vibration detection device based on the digital image correlation algorithm can be used to simulate and study the vibration characteristics of the solar panel body after it is deployed.

The dimensions of the three honeycomb sandwich panels used in this example are all 500mm×500mm×16.3mm, and the shape of each cell of the honeycomb core is a regular regular hexagon with a side length of 6mm and a wall thickness of 0.07mm , 15mm high, the material grade is A3003-H19, the panel thickness is 0.5mm, and the epoxy resin material is used. The modulus of elasticity of the epoxy resin is E _p =34.64Gpa, and the density is ρ=1840kg/m ³ . The industrial camera (1) selects the GIGE camera model acA1600-60gc produced by Basler, Germany, adopts CMOS photosensitive chip, the highest frame rate is 60fps, and the resolution is 1600×1200; the lens of Ricoh Company is selected, and its model is FL-HC0614- 2M, the focal length is 6mm, and the size is Φ32mm×35.7mm. The point shooter (3) selects the model of PRO-SPOT/A produced by GeodeticSystem Company, which can project 600-2300 points at a time, and the accuracy can reach 10 μm. The exciter (8) selects the APA1000XL exciter produced by Cedrat Technologies, which can produce a maximum displacement of 1297um under no-load conditions, a maximum excitation force of 471.21N, and an accuracy of 10.99nm; the high-voltage amplifier (12 ) Select the model 2350 dual-channel amplifier produced by Tegam Company, with a maximum peak value of 400Vp-p.

Example 2:

This embodiment provides a method for detecting vibration of a hinged honeycomb panel based on a digital image correlation algorithm, the method comprising the following steps:

Step 1, the vibration excitation signal that computer (13) sends is transmitted to high-voltage amplifier (12) after A/D conversion, and signal is transmitted to three exciters (8) after high-voltage amplifier (12) amplifies, and vibrator ( 8) According to different combinations of signals, the body of the hinged honeycomb panel is excited to bend or torsionally vibrate;

In this step, by transmitting excitation signals of the same frequency and phase to the three exciters (8), the bending vibration of the hinged honeycomb panel body can be excited; by transmitting the same frequency, The anti-phase signal can excite the torsional vibration of the hinged honeycomb panel body.

Step 2: Turn on the dot projector (3), and evenly project the light spot onto the surface of the second honeycomb sandwich panel (6) and the third honeycomb sandwich panel (4). The schematic diagram of the light spot field formed by the projection point is shown in Figure 4. Form a spot field with continuous characteristic areas, use a binocular vision measurement system composed of two industrial cameras (2) to collect continuous images of the hinged honeycomb panel vibration body, divide and select interesting characteristic sub-areas on the image, and run the corresponding The digital image correlation algorithm is used to obtain the three-dimensional coordinate information of the region of interest, so as to indirectly obtain the vibration information of the hinged honeycomb panel body;

In this step, the characteristic sub-region of interest is divided and selected on the collected continuous images as the reference position for vibration detection, and the statistical correlation before and after the vibration of the position is analyzed by matching the images containing the sub-region before and after the vibration. Determine and extract the vibration displacement information of the hinged honeycomb panel vibration body. By changing the number of regions of interest and their positions on the hinged honeycomb panel vibration body, the vibration information of different parts of the hinged honeycomb panel body can be collected simultaneously during the detection process. In this way, it can be used to measure the multi-order mode coupling vibration of the hinged honeycomb panel to realize the decoupling of vibration.

Among them, the schematic diagram of the digital image correlation algorithm including sub-region images before and after vibration matching is shown in Figure 5. One of the images is used as a reference image, denoted as f(x, y), and the other is used as an image to be matched, denoted as g (x, y), the two-dimensional digital correlation method matches two images through correlation operations to obtain the displacement field. Select a (2n+1)×(2n+1) sub-area centered on M(x ₀ , y ₀ ) in the reference image f(x, y), use the gray information in the sub-area, and pass a certain Correlation matching algorithm, perform progressive scanning operation on the area to be matched in the image to be matched g(x, y), find the target image sub-area centered on M′(x ₀ ′, y ₀ ′), the image sub-area can be Divide and select by yourself according to the vibration information to be extracted.

The three-dimensional digital correlation method combines the two-dimensional digital correlation method with the binocular stereo vision measurement, and the matching includes two links in the measurement process of the three-dimensional digital correlation method: two-dimensional matching and stereo matching. Two-dimensional matching refers to the matching of images before and after vibration of an object collected by the same camera, and stereo matching refers to the matching of left and right images at the same time. The stereo matching process can also use the matching method shown in Figure 5.

The similarity criterion adopted in the present embodiment is normalized cross-correlation (NCC), and the calculation formula is:

The range of NCC(x, y) of the correlation coefficient matrix calculated by this algorithm is [-1, 1]. The position with a coefficient of 1 indicates a perfect match, -1 indicates a bad match, and 0 indicates no correlation. Considering the influence of interference noise and other factors, the correlation coefficient of the best matching position is usually taken as 0.8.

Step 3. By changing the form, frequency, and amplitude parameters of the excitation signal, repeated experiments, and obtaining multiple experimental results, the vibration characteristics of the hinged honeycomb panel body are obtained.

The above is only a preferred embodiment of the patent of the present invention, but the scope of protection of the patent of the present invention is not limited thereto. The equivalent replacement or change of the technical solution and its invention patent concept all belong to the protection scope of the invention patent.

Claims (5)

1. A hinged honeycomb panel vibration detection device based on a digital image correlation algorithm, characterized in that: comprise a hinged honeycomb panel body part, a projection measurement part, a vibration excitation part and a computer, and the hinged honeycomb panel body part comprises three pieces of material, The honeycomb sandwich panels with the same size are respectively the first honeycomb sandwich panel, the second honeycomb sandwich panel and the third honeycomb sandwich panel, and every two honeycomb sandwich panels pass through two inter-panel hinges at the upper and lower symmetrical positions Connected together, the first honeycomb sandwich panel end of the hinged honeycomb panel body is mechanically connected to the metal support through the splint and the steel frame, and the metal support is vertically fixed on the horizontal experimental platform. One end is a free end, and the hinged honeycomb panel body is perpendicular to the horizontal plane of the experimental pedestal; the projection measurement part includes a point thrower and two industrial cameras, and the point thrower and two industrial cameras are fixed on the tripod, and the point thrower The mirror surface of the hinged honeycomb panel is directly facing the surface of the hinged honeycomb panel body, and two industrial cameras are respectively installed on both sides of the point thrower to ensure that its field of view fully includes the second honeycomb sandwich panel and the third honeycomb sandwich panel; the vibration excitation part Including three exciters of the same type and supporting high-voltage amplifiers, the three exciters are evenly distributed in the width direction of the first honeycomb sandwich panel close to the metal support, and the positions of the upper and lower two exciters are relative to the width direction The center line is symmetrical, and the exciter in the middle position is located on the center line in the width direction; The honeycomb sandwich panel is composed of a honeycomb core, an adhesive layer and a panel, and the adhesive layer glues the upper and lower panels and the honeycomb core into an integral rigid structure; The inter-panel hinge is composed of a male hinge, a female hinge, a coil spring, a pin shaft, a locking swing lever and an eccentric screw. When the inter-panel hinge is unfolded, the male hinge and the female hinge are opposite to each other around the pin shaft under the action of the coil spring of the driving element. Rotate, during the rotation process, the pin on the locking swing rod first slides along the unfolding slideway on the male hinge, and at the end of the unfolding process, slides in along the left side of the locking groove on the male hinge and finally gets stuck in the locking groove Bottom: In the locked state, the positional relationship between the honeycomb sandwich panels is fixed, and the hinged honeycomb panel body is fully unfolded. In this state, the hinged honeycomb panel body can be regarded as a whole rectangular plate. 2. A vibration detection device for hinged honeycomb panels based on digital image correlation algorithm according to claim 1, characterized in that: said vibration detection device for hinged honeycomb panels based on digital image correlation algorithm can be used to simulate and study solar sails The vibration characteristics of the body of the plate after unfolding. 3. a method for the hinged honeycomb plate vibration detection device based on digital image correlation algorithm as claimed in claim 1, is characterized in that, described method comprises the following steps: Step 1. The vibration excitation signal sent by the computer is transferred to the high-voltage amplifier after A/D conversion. The signal is amplified by the high-voltage amplifier and then transmitted to the three exciters. The exciters excite the hinged honeycomb panel body to bend or bend according to different combinations of signals. torsional vibration; Step 2. Turn on the dot projector and evenly project the light spot onto the surface of the second honeycomb sandwich panel and the third honeycomb sandwich panel to form a spot field with continuous characteristic areas. Use the binocular vision measurement system composed of two industrial cameras to measure the The vibration body of the hinged honeycomb panel collects continuous images, divides and selects the characteristic sub-regions of interest on the image, runs the corresponding digital image correlation algorithm, obtains the three-dimensional coordinate information of the region of interest, and indirectly obtains the vibration information of the hinged honeycomb panel body ; Step 3. By changing the form, frequency, and amplitude parameters of the excitation signal, repeated experiments, and obtaining multiple experimental results, the vibration characteristics of the hinged honeycomb panel body are obtained. 4. a kind of hinged honeycomb panel vibration detection method based on digital image correlation algorithm according to claim 3, is characterized in that: in step 1, by giving three exciters the excitation signal of same frequency, same phase, can The bending vibration of the hinged honeycomb panel body is excited; the torsional vibration of the hinged honeycomb panel body can be excited by transmitting signals of the same frequency and opposite phase to the exciters at the upper and lower ends. 5. a kind of hinged honeycomb plate vibration detection method based on digital image correlation algorithm according to claim 3, is characterized in that: in step 2, on the continuous image of collecting, divide and select the characteristic subregion of interest, with this As a reference position for vibration detection, the vibration displacement information of the hinged honeycomb panel vibration body is determined and extracted by matching the images containing the sub-region before and after the vibration, and analyzing the statistical correlation before and after the vibration of the position. By changing the number of regions of interest and Its position on the vibration body of the hinged honeycomb panel can simultaneously collect the vibration information of different parts of the hinged honeycomb panel body during the detection process, so that it can be used to measure the multi-order modal coupling vibration of the hinged honeycomb panel to achieve vibration decoupling .

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