CN108709626A - A kind of vibration detection device and method of truss support circular membrane structure - Google Patents

Abstract

The invention discloses a vibration detection device and method for a truss-supported circular film structure, which includes a film body and an excitation detection part; the film body includes a disc type film, a support plate and a telescopic truss, and the excitation detection part High-speed cameras, lasers, exciters, computers, signal generators and power amplifiers. The vibration detection device of the present invention is composed of a binocular vision system, which can perform non-contact measurement on the measurement body without bringing additional load effect to the system, making the system robust and obtaining more accurate vibration of the disc-type film structure information.

Description

A vibration detection device and method for a truss-supported circular membrane structure

technical field

The invention relates to the field of vibration measurement of flexible structures, in particular to a vibration detection device and method for a truss-supported circular membrane structure.

Background technique

Since the 21st century, the complexity of the tasks undertaken by spacecraft has been increasing, and people have higher and higher requirements for its structure. On the one hand, it is required to increase the carrying capacity, and on the other hand, it is required to reduce the total mass of the structure. With the trend of low stiffness, flexibility, and large-scale development, great flexibility has become a major feature of modern spacecraft. Flexible structures widely exist in spacecraft, such as solar panel structures of satellites or space workstations, spaceflight wings, flexible robotic arms of space stations, large parabolic antennas, etc. From their structural characteristics, spacecraft with flexible structures can be divided into three categories : Central rigid body with various large-scale flexible attachment spacecraft, central rigid body with large composite flexible structural attachment spacecraft, fully flexible structural spacecraft. The spatial scale of these flexible structures is relatively large, up to tens of meters or even hundreds of meters. They are made of materials with low density and low stiffness, and have physical characteristics such as large deflection, nonlinearity, small damping, low and dense modal frequencies.

Non-contact measurement has many advantages over traditional sensor contact measurement. Non-contact measurement will not affect the dynamic performance of the measured object, and will not affect its normal work due to the additional mass of the measured object. It is non-destructive to the measured object and has strong anti-interference ability. However, non-contact measurements are generally less accurate than contact measurements. Non-contact measurement is a simple and effective vibration measurement method. Common methods include laser vibrometers, laser sensors, and binocular vision systems. Among them, the vibration measurement method of the binocular vision system composed of two high-speed cameras is With the development and maturity of image processing and analysis technology, it has become a simple and convenient vibration measurement method with high use value.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a vibration detection device and method for a truss-supported circular membrane structure.

The binocular vision system composed of high-speed cameras in the present invention takes high-frequency photographs of marking points in the measured area on the surface of the film, acquires image sequences, cooperates with corresponding image processing and analysis, and obtains vibration information of the unfolded structure of the film.

The present invention adopts following technical scheme:

A vibration detection device for a circular membrane structure supported by a truss, comprising a membrane body and an excitation detection part;

The film body includes a disc film, a support plate and a telescopic truss, the disc film is fixed on the support plate, and the telescopic truss is used to support the support plate, the disc film includes an unfolded state and a tightened state, and the drive The support plate realizes the disc film from the tightened state to the unfolded state;

The excitation detection part includes two high-speed cameras, a laser, an exciter, a computer, a signal generator and a power amplifier;

Described two high-speed cameras are installed on the camera support, make the disc-type film of unfolded state be positioned at the field of view range of two high-speed cameras, and the optical axis of high-speed camera is perpendicular to the face of disc-type film;

The laser is positioned directly above the center of the unrolled disc-shaped membrane, projecting a laser spot;

The signal generator sends a vibration signal, which is amplified by a power amplifier to drive the vibrator to further excite the vibration of the disc-shaped membrane in the unfolded state;

Two high-speed cameras capture images containing the laser dots and feed them into a computer.

The laser spots are specifically a symmetrical "starry sky" circular array of laser spots.

It also includes a guide rail backing plate, a guide rail, a cloud platform and a sliding seat, the high-speed camera is fixed on the sliding seat through the cloud platform, the sliding seat is fixed on the guide rail through the guide rail backing plate, and the guide rail is fixed on the camera bracket.

Specifically, there are four vibrators, which are respectively fixed on the diagonal lines of the test bench, and the ejector rods of the vibrator are connected with the support plate.

The disc-shaped film is a planar figure without curved surface.

Specifically, there are twelve support plates.

The disc film is a plastic film.

A method for a vibration detection device of a truss supporting a circular film structure, comprising the steps of:

In the first step, the laser is powered on, emits laser light, and adjusts the focal length of the laser light emitted by the laser to meet the shooting requirements;

In the second step, the signal generator sends out a vibration signal, which is amplified by the power amplifier and sent to the vibrator, and the vibrator excites the disc-type film expansion structure through the ejector pin of the vibrator to generate vibrations of different frequencies;

In the third step, during the vibration process of the film unfolding structure, the binocular vision system composed of two high-speed cameras performs synchronous high-frequency shooting on the vibration detection mark area on the film, collects image sequences, and sends them to the computer;

In the fourth step, the computer reads the image captured by the high-speed camera, calibrates the two industrial cameras through the Zhang Zhengyou calibration method, extracts the image spot features to calculate the coordinates of the laser point, and further processes to obtain the vibration information of the film unfolding mechanism, which is then visualized.

The vibrator excites the flexural mode vibration and torsional mode vibration of the film unfolded structure through the vibrator ejector rod respectively; when the vibrator receives a sinusoidal signal with the same frequency as the bending mode excitation, the vibrator will press the same signal and phase If the excitation is the same, the bending vibration of the unfolded structure of the membrane is excited; when the two exciters are excited by a sinusoidal signal with the same frequency as the torsional mode, the two exciters are excited by the same signal and the phase is opposite, and the excitation produces a thin film Torsional vibrations of an unfolded structure.

Beneficial effects of the present invention:

(1) The vibration measuring device of a kind of disc type film unfolding structure of the present invention is formed binocular vision system by two high-speed cameras, can carry out non-contact type measurement to vibrating body under the premise of not bringing additional effect to the system, The system robustness is improved, so the measurement accuracy is relatively high.

(2) Because of the large volume of the disc-type film expansion structure, the vibration detection device of the present invention adopts the multi-point measurement mode of the binocular vision system to detect the film expansion structure body, and can perform multi-order mode coupling vibration of the film Decoupling, more accurately restore the vibration of the vibration body.

(3) The present invention adopts the bracket structure capable of horizontal displacement formed by guide rails, sliders, and pan-tilts, and cooperates with the truss structure adjustable in height to form a binocular vision system capable of horizontal and vertical displacement, which is beneficial to camera calibration and Vibration measurement of membranes of different shapes and sizes to obtain more accurate vibration characteristics of membrane unfolded structures.

Description of drawings

Fig. 1 is the overall structural representation of the present invention;

Fig. 2 is the front view of the present invention;

Fig. 3 is the top view of the present invention;

Fig. 4 is a right side view of the present invention.

Detailed ways

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

Example

As shown in Figures 1-4, a vibration detection device for a circular film structure supported by a truss, including a film body and an excitation detection part;

The film body includes a disc film 9, a support plate 10 and a telescopic truss 11, the disc film is fixed on the support plate, and the telescopic truss is used to support the support plate. The disc-shaped film includes an unfolded state and a tightened state. The disc-shaped film in the unfolded state is fully unfolded, and the telescopic truss is in a locked state after unfolding; The tight and locked states do not consider the vibration effect caused by the unfolding process. All the following are fully unfolded films.

The support plate is connected with the drive expansion mechanism through a cylindrical support and fixed on the test bench. The film is a flat circle without a curved surface, so that the disc-type film under tension remains parallel to the test bench. There are twelve support plates. , evenly arranged under the disc film according to the circumference, and connected with the film, the driving expansion mechanism drives the support plate to make the disc film open sequentially like a fan, and gradually expand into a whole circle. The film body is in the center of the test bench, which is convenient for image acquisition of vibration detection and symmetrical installation of excitation. The test bench 1 is made of aluminum profiles, fixed by corner fittings, and finally the panel and the connecting feet in contact with the ground are installed by screws at the four corners.

In this embodiment, the experimental bench 1 is assembled from three kinds of aluminum profiles with lengths of 4500mm and 500mm respectively. Angle iron fixed. The maximum size of the disc-type film unfolding mechanism is Φ1700mm×400mm, the telescopic truss and the support plate are made of aluminum, and the film is plastic film.

Excitation detection part: including two high-speed cameras 5, a laser 7, an exciter 2, a computer 12, a signal generator 14 and a power amplifier 13;

Two high-speed cameras form a double-sided visual inspection system, which are installed on two sliding seats 8 through two pan-tilts 6 respectively. The two sliding seats 8 can move on the guide rail 4, and the guide rail 4 is fixed on the camera support. It can slide on the guide rail 4 fixed on the camera bracket by the guide rail backing plate 3 to change the positional relationship between the two high-speed cameras 5. For the vibration detection of membrane structures of various shapes and sizes, the position of the camera should be such that the detection end surface of the disc-type membrane structure is roughly in the middle of the camera field of view when the structure is stationary, so as to ensure that when the membrane vibrates, the disc-type membrane structure is always in the field of view of the camera. Within the scope of the field, the continuity of the measurement is guaranteed. The optical axis of the camera is perpendicular to the surface of the film, so that the camera can shoot the surface of the film from the front.

The camera bracket is composed of three pillars, two of which are arranged parallel to each other, and the third is vertically arranged on the upper end of the two pillars, and the high-speed camera and laser are installed on the pillars arranged horizontally.

The laser is located directly above the center of the entire disk-shaped film, thereby projecting a symmetrical "starry sky"-style circular array of laser points as mark points, which is convenient for the binocular vision system to identify and capture images; the size of the point of the mark dot matrix , spacing, color and focal length are all adjustable, which can meet the vibration detection requirements of different sizes of detection bodies and different installation heights, and the laser can work continuously for a long time without light attenuation, and has a strong line forming effect. It has anti-seismic performance and can reduce the impact of body vibration.

In this embodiment, the high-speed camera selected from Wuhan Zhongchuang Lianda Technology Co., Ltd. is a high-speed camera model of Memrecam HX-3E, which has 5 million pixels and a frame rate of 2000 frames per second at the full resolution, and full HD pixels. The speed is up to 4670 frames per second, 1 million pixels is up to 9220 frames per second, the memory is 64GB, the working temperature range is 0-40 degrees Celsius, the weight is about 5.9 kg, and the required power supply is 100-240V AC-1.5A, 50-60Hz. The laser is ZLM100MTX650-16GD laser from Shenzhen Zhonglai Technology Co., Ltd., the laser wavelength is 650nm, the output power is 100mW, the working current is ≤180mA, the power supply voltage is DC2.8-5.2V, spot mode, dot matrix, optical lens: grating (Imported from Germany).

Specifically, there are four exciters, and the four corners are respectively fixed on the diagonal line of the experimental table by screws, and the ejector rod of the exciter is connected with the cushion block installed on the support plate; the vibration excitation part receives the signal and generates The vibration signal generated by the device 14 is amplified by the power amplifier 13, and the disc-type film unfolded structure is excited by the ejector pin of the vibrator to generate bending mode vibration and torsional mode vibration.

The vibrator respectively excites the flexural mode vibration and the torsional mode vibration of the film unfolded structure through the vibrator push rod; when the vibrator receives the excitation of the sinusoidal signal with the same frequency as the When the two exciters are excited by the sinusoidal signal with the same frequency as the torsional mode, the two exciters are excited by the same signal and the phase is opposite, then The excitation produces torsional vibrations of the membrane unfolded structure.

The binocular vision measurement model is to use two high-speed cameras to collect images of the same target at the same time to obtain the images of the target on the left and right cameras, and then use the binocular vision parallax principle to remove Compute the spatial coordinates of this object. The binocular vision measurement system is divided into two types according to the placement form: one is the ideal measurement model where the two cameras are placed absolutely parallel; the other is the measurement model where the optical axes of the two cameras are not parallel. In fact, absolutely parallel placement is impossible, so in the application of binocular vision measurement, non-parallel placement models are used. At present, the calibration method of industrial-level computer vision measurement is Zhang Zhengyou's plane calibration method. Only a simple and accurate calibration template is needed for calibration, and the calibration accuracy is high.

The laser is powered on and emits laser light. The signal generator 14 sends out a vibration signal, which is amplified by the power amplifier 13 and then sent to the exciter 2. The exciter 2 excites the disc-type thin film unfolded structure through the ejector pin of the exciter to generate vibrations of different frequencies. Vibration; two high-speed cameras perform synchronous high-frequency shooting on the vibration detection mark area on the film, and the image sequence is collected and sent to the computer. The computer 12 reads the images captured by the high-speed camera, and uses the Zhang Zhengyou calibration method to compare the two industrial cameras. Carry out calibration, extract the image spot features to calculate the coordinates of the laser point, and further process to obtain the vibration information of the film unfolding mechanism, and perform visualization processing.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (9)

1. a kind of vibration detection device of truss support circular membrane structure, which is characterized in that including film bulk and excitation detection Part；

The film bulk includes disc type film, support plate and flexible truss, and the disc type film is fixed on support plate, stretches Contracting truss is used to support support plate, and the disc type film includes unfolded state and tightening state, and driving support plate realizes disk Formula film is by tightening state to unfolded state；

The excitation detection part is put including two high speed cameras, laser, vibrator, computer, signal generator and power Big device；

Described two high speed cameras are mounted on camera support so that the disc type film of unfolded state is located at two high speed cameras Field range in, and the optical axis of high speed camera is vertical with the face of disc type film；

Laser is located at right over the center of the disc type film of unfolded state, projects laser point；

The signal generator sends out vibration signal, and vibrator is driven after power amplifier amplifies, further excitation expansion shape The thin vibration of membrane of disc type under state；

Two images of the high speed camera shooting comprising laser point input computer.

2. vibration detection device according to claim 1, which is characterized in that the laser point is specifically symmetrical " all over the sky The circumference array laser point of star " formula.

3. vibration detection device according to claim 1, which is characterized in that further include guide rail backing plate, guide rail, holder and cunning Seat, the high speed camera are fixed on by holder on slide, and slide is fixed on by guide rail backing plate on guide rail, and the guide rail is fixed On camera support.

4. vibration detection device according to claim 1, which is characterized in that there are four the exciting implement bodies, solid respectively It is scheduled on the diagonal line of experimental bench, the mandril of vibrator is connect with support plate.

5. vibration detection device according to claim 1, which is characterized in that the disc type film is the flat of not curved surface Face figure.

6. according to claim 1-5 any one of them vibration detection devices, which is characterized in that the support plate is specially 12 Block.

7. according to claim 1-5 any one of them vibration detection devices, which is characterized in that the disc type film is plastics Film.

8. a kind of method of the vibration detection device of truss support circular membrane structure of claim 1-7 any one of them is applied, It is characterised in that it includes following steps：

First step laser turn-on power supply emits laser, adjusts the focal length of the sent out laser of laser, reaches photographing request；

Second step signal generator sends out vibration signal, vibrator is sent to after power amplifier amplifies, vibrator is by swashing The device mandril that shakes encourages the vibration of disc type film deployed configuration generation different frequency；

Third walks during film deployed configuration vibrates, and the binocular vision system being made of two high speed cameras is on film Vibration detection index point region synchronize high frequency shooting, collect image sequence, be sent to computer；

Four-step calculation is machine-readable to take the image that high speed camera takes, by two industrial cameras of Zhang Zhengyou standardizations pair into rower It is fixed, the coordinate of image spot feature calculation laser point is extracted, is further processed to obtain the vibration information of film unfolding mechanism, go forward side by side Row visualization processing.

9. the method according to claim 8, which is characterized in that vibrator encourages film exhibition by vibrator mandril respectively Opening structure mode of flexural vibration vibrates and torsion mode vibration；Swash when vibrator receives sinusoidal signal identical with mode of flexural vibration frequency When encouraging, vibrator presses identical signal and the identical excitation of phase, then encourages the bending vibration of film deployed configuration；When two vibrators When receiving sinusoidal signal excitation identical with Torsion mode frequency, two vibrators are swashed by identical signal and opposite in phase It encourages, then encourages the twisting vibration for generating film deployed configuration.