Method for measuring three-dimensional vibration parameters of rigid long pipe fitting

Abstract

The invention relates to a method for measuring three-dimensional vibration parameters of a rigid long pipe fitting. The method comprises the following steps: arranging a three-line array camera intersection measurement system; the expansion amount proportion measuring pattern is pasted on the long pipe fitting, the pattern is rectangular, the length is L, the width is L, a black equilateral triangle with the side length being L is made with the length L as the bottom and the midpoint of the opposite sides as the vertex, the other parts are white, and a linear array camera is aligned to the center of the pattern; the three linear array cameras continuously shoot images of the long pipe fitting in the whole vibration process; the image acquisition platform measures the length value of the middle black stripe image of the pattern shot by the line-scan digital camera; and the vibration parameters of the long pipe fitting are calculated by combining the obtained position coordinates of the long pipe fitting. According to the invention, the abscissa, the ordinate and the expansion amount of the long pipe fitting in the space can be measured at the same time; the measurement process is simplified; real-time measurement of vibration parameters of the long pipe fitting is achieved, and a reliable method is provided for efficient acquisition of high-speed vibration parameters of the long pipe fitting.

Description

Technical Field

[0001] This invention belongs to the field of motion parameter testing technology, specifically relating to a method for measuring the three-dimensional vibration parameters of a rigid long pipe. Background Technology

[0002] With the rapid development of modern weaponry, higher demands are placed on range testing technology, including diversified test parameters, high precision, and multi-parameter collaborative testing. The vibration parameters of the artillery barrel during firing directly affect the projectile's exit trajectory, thus determining the accuracy and destructive force of the artillery strike the target. These vibration parameters include the two-dimensional position coordinates of the long barrel, the amount of expansion and contraction of the barrel, and the vibration tilt angle, all of which need to be accurately measured during testing. Measuring barrel vibration during firing presents challenges such as harsh environments, numerous interference factors, small vibration amplitude, and difficulty in capturing and identifying vibrations, making it one of the difficulties in range testing.

[0003] Methods for measuring gun barrel vibration both domestically and internationally are mainly divided into contact and non-contact measurements, with non-contact methods becoming increasingly widely used. Non-contact measurements mostly employ photoelectric displacement sensors and high-speed cameras. Photoelectric displacement sensors are primarily suitable for one-dimensional motion, and cannot meet the measurement requirements for two-dimensional and three-dimensional gun barrel vibrations. High-speed camera measurement methods, primarily using area array cameras, are widely used for measuring gun barrel vibrations in various types of artillery. However, high-speed area array cameras are expensive, require pre-calibration, and have large data storage requirements, which complicates subsequent image processing.

[0004] Line array cameras employ the principle of line scanning imaging and are often used to measure the characteristic parameters of moving objects. They have significant research value and wide application value in areas such as vibration research of long tubes, performance evaluation of artillery, and health monitoring of barrel structures.

[0005] The "Non-Contact Measuring Device" disclosed in application number "202310611263.5" utilizes two sets of measuring optical path systems and a dual-line array camera signal acquisition and processing device for measurement. The two measuring optical path systems generate line laser surfaces using lasers and cylindrical lenses, respectively, which illuminate the muzzle to form a projection. The image is then transmitted to the line array camera via reflectors and filters. By establishing coordinate systems on the muzzle and the two line array cameras, the coordinates of the projected image are obtained. Then, using a coordinate transformation matrix, the plane coordinates of the line array camera image are converted into three-dimensional coordinates of the muzzle vibration. However, the core design objective of this system is to measure the vertical and horizontal displacement of the gun barrel caused by vibration; it cannot measure the expansion and contraction displacement of the gun barrel during vibration. Summary of the Invention

[0006] This invention provides a method for measuring the three-dimensional vibration of rigid long pipes, in order to solve the problem that existing testing methods cannot accurately measure the expansion and contraction displacement of long pipes during vibration.

[0007] To achieve the above objectives, the technical solution of the present invention is: a method for measuring the three-dimensional vibration parameters of a rigid long pipe, the specific steps of which are as follows:

[0008] Step 1: Arrangement of the three-line array camera intersection measurement system; Line array camera A is arranged on the outside of the long tube, and line array cameras B and C are symmetrically arranged on both sides of line array camera A. The optical imaging parameters of line array cameras A, B and C are the same, linearly arranged and the line connecting them is perpendicular to the length direction of the long tube. The principal optical axes of the three line array cameras intersect at a point in the object space. The virtual photoelectric intersection imaging light curtain formed by their intersection field of view passes through the radial surface of the long tube.

[0009] Step 2: Attach the expansion / contraction ratio measurement pattern to the belly of the long pipe fitting; the expansion / contraction ratio measurement pattern is rectangular, with a length of L and a width of [missing information]. With length L as the base and the midpoint of opposite sides as the vertex, construct a black equilateral triangle with side length L. The rest of the rectangle is white. Mark the center of the stretching ratio measurement pattern and align the center field of view of the line scan camera A with the center of the pattern.

[0010] Step 3: When the long pipe vibrates, three line scan cameras use synchronous triggering to continuously capture images of the long pipe throughout the entire vibration process.

[0011] Step 4: The image acquisition platform acquires images captured by three line scan cameras. The length of the central black stripe image of the scaling ratio pattern captured by line scan camera A is measured. The position coordinates of the long tube within the imaging screen are obtained through line scan cameras B and C. The vibration parameters of the long tube are calculated by combining the two, including the horizontal coordinate, the vertical coordinate, and the scaling.

[0012] Furthermore, in step four above, the formula for calculating the front-to-back expansion and contraction displacement of the long pipe fitting is:

[0013]

[0014] Wherein, ΔL(t) is the difference in length of the middle black stripe at different times; the value of L(t) is obtained by combining the ordinate of the long tube in the imaging screen measured by line scan camera B and line scan camera C with the optical vertical magnification calculation formula.

[0015] Furthermore, in step four above, the formula for calculating the length L(t) of the middle black stripe is:

[0016]

[0017] Where, L(t) ’ Let y(t) represent the length of the central black stripe, y(t) be the ordinate of the long pipe, and r be the radius of the long pipe. ’ The value is equal to the focal length of the optical system.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention employs a three-line array camera intersection testing system. By using the imaging screen formed by the intersection of the three line array cameras in the testing system, combined with the designed stretching ratio measurement pattern, the changing posture of the long pipe during vibration is obtained, and the parameters of the long pipe vibration are measured. The horizontal coordinate, vertical coordinate and stretching amount of the long pipe in space can be measured simultaneously.

[0020] 2. This invention simplifies the measurement process by using three line array cameras in a coordinated layout and synchronous acquisition. By adding a line array camera A and combining it with the telescopic measurement of special patterns, the invention enables real-time measurement of vibration parameters of long pipe components, providing a new method for the efficient acquisition of high-speed vibration parameters of long pipe components. Attached Figure Description

[0021] Figure 1 This is a layout diagram of the method according to an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram illustrating the measurement principle of an embodiment of the present invention;

[0023] Figure 3 This is the pattern style for measuring the stretching ratio in an embodiment of the present invention;

[0024] Figure 4 The image shows a sticker captured by a camera during the flight of a long tube, according to an embodiment of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0026] Example: This invention provides a method for measuring the three-dimensional vibration parameters of a rigid long pipe, comprising the following specific steps:

[0027] Step 1: Setup of the three-line array camera intersection measurement system:

[0028] Linear array camera A is arranged on the outside of the long tube. Linear array cameras B and C are symmetrically arranged on both sides of line array camera A. The optical imaging parameters of line array cameras A, B, and C are the same, they are linearly arranged, and the line connecting them is perpendicular to the length direction of the long tube. The principal optical axes of the three line array cameras intersect at a point in the object space. The virtual photoelectric intersection imaging light curtain formed by their intersection field of view passes through the radial surface of the long tube, thus forming a three-line array camera intersection measurement system.

[0029] This invention utilizes the principle of intersecting and measuring spatial coordinates using line array cameras. The key is that the imaging planes of the three cameras must remain aligned. After setting up the three-line array camera intersecting and measuring system, a linear laser is used to indicate the imaging planes of line array cameras A, B, and C, and the imaging planes of the three line array cameras are adjusted to ensure they are aligned.

[0030] Step 2: Attach the expansion / contraction ratio measurement pattern to the belly of the long pipe fitting.

[0031] The stretch / expansion ratio measurement pattern is rectangular, with a length of L and a width of [missing information]. With length L as the base and the midpoint of opposite sides as the vertex, construct a black equilateral triangle with side length L. The rest of the rectangle is white. Mark the center of the stretching ratio measurement pattern and align the center field of view of the line scan camera A with the center of the pattern.

[0032] Step 3: When the long pipe vibrates, three line scan cameras use synchronous triggering to continuously capture images of the long pipe throughout the entire vibration process.

[0033] Step 4: The image acquisition platform acquires images captured by three line scan cameras. The length of the black stripe in the middle of the pattern is measured by the scaling ratio captured by line scan camera A. The position coordinates of the long tube within the imaging screen are obtained through line scan cameras B and C. The vibration parameters of the long tube are calculated by combining the two, including the horizontal coordinate, the vertical coordinate, and the scaling.

[0034] The abscissa and ordinate of the vibration parameters are calculated as follows:

[0035] Let the optical center of line scan camera B be the origin O, the line perpendicular to the horizontal plane passing through this origin O be the Y-axis, and the line connecting the optical centers of line scan cameras B and C be the X-axis. The two-dimensional position coordinates of any point S within the imaging screen area of ​​the overlapping three line scan cameras can be calculated using the following formula:

[0036]

[0037] x-axis:

[0038] Vertical axis:

[0039] The image heights h1(t) and h2(t) of the long tube in line array camera B and line array camera C, and the image height h3(t) of the long tube in line array camera A, are determined by the focal length f of the optical system, the baseline length d0, and the angles α0 and β0. Then the coordinates of any point within the imaging screen can be determined.

[0040] The formula for calculating the front-to-back expansion and contraction displacement of the long pipe is as follows:

[0041]

[0042] Where: ΔL(t) is the difference in the length of the middle black stripe in the image of the expansion and contraction ratio measured by line scan camera A at different times during the vibration of the long tube. The value of L(t) is obtained by combining the ordinate of the long tube in the imaging screen measured by line scan camera B and line scan camera C with the formula for calculating the optical vertical magnification.

[0043] Specifically, the formula for calculating the length L(t) of the middle black stripe of the stretch / scaling ratio measurement pattern is as follows:

[0044]

[0045] Where, L(t) ’ Let y(t) be the length of the black stripe in the center of the stretching ratio measurement pattern captured by line scan camera A, where y(t) is the ordinate of the long pipe and r is the radius of the long pipe. ’ The value is equal to the focal length of the optical system.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for measuring three-dimensional vibration parameters of a rigid long pipe, characterized in that: The specific steps are as follows: Step 1: Arrangement of the three-line array camera intersection measurement system; Line array camera A is arranged on the outside of the long tube, and line array cameras B and C are symmetrically arranged on both sides of line array camera A. The optical imaging parameters of line array cameras A, B and C are the same, linearly arranged and the line connecting them is perpendicular to the length direction of the long tube. The principal optical axes of the three line array cameras intersect at a point in the object space. The virtual photoelectric intersection imaging light curtain formed by their intersection field of view passes through the radial surface of the long tube. Step 2: Attach the expansion / contraction ratio measurement pattern to the belly of the long pipe fitting; the expansion / contraction ratio measurement pattern is rectangular, with a length of L and a width of [missing information]. L, with length L as the base and the midpoint of the opposite side as the vertex, construct a black equilateral triangle with side length L, and the rest of the rectangle is white; mark the center of the stretching ratio measurement pattern, and align the center field of view of the line scan camera A with the center of the pattern. Step 3: When the long pipe vibrates, three line scan cameras use synchronous triggering to continuously capture images of the long pipe throughout the entire vibration process. Step 4: The image acquisition platform acquires images captured by three line scan cameras. The length of the central black stripe image of the scaling ratio pattern captured by line scan camera A is measured. The position coordinates of the long tube within the imaging screen are obtained through line scan cameras B and C. The vibration parameters of the long tube are calculated by combining the two, including the horizontal coordinate, the vertical coordinate, and the scaling.

2. The method for measuring three-dimensional vibration parameters of a rigid long pipe according to claim 1, characterized in that: In step four, the formula for calculating the front-to-back expansion and contraction displacement of the long pipe is as follows: in, The difference in length of the middle black stripe at different times; The value is derived from the ordinate of the long tube within the imaging screen measured by line scan camera B and line scan camera C, combined with the formula for calculating the optical vertical magnification.

3. The method for measuring three-dimensional vibration parameters of a rigid long pipe according to claim 2, characterized in that: In step four, the length of the middle black stripe The calculation formula is: in, The length of the black stripe in the middle. Let be the ordinate of the long pipe fitting, and r be the radius of the long pipe fitting. The value is equal to the focal length of the optical system.

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