Four-degree-of-freedom automated acoustic holography scanning test analysis system

Abstract

A kind of four degrees of freedom automation acoustic holography scanning test analysis system, comprising: acoustic holography test platform, microphone circumferential array, PLC control device, data acquisition device and analysis module, wherein: acoustic holography test platform is connected with PLC control device and the sound source to be measured is placed in acoustic holography test platform, microphone circumferential array is set on acoustic holography test platform and is connected with data acquisition device, analysis module determines measurement position according to the position of the sound source to be measured and the size of microphone circumferential array and exports to PLC control device, after microphone circumferential array is moved to measurement position by PLC control device, using microphone circumferential array, the measuring point is scanned and measured on the holographic surface of the object to be measured, and the sound pressure signal of the measuring point is collected by data acquisition device and the sound source distribution of the object to be measured is obtained according to acoustic holography scanning algorithm by analysis module.The present application realizes that microphone circumferential array is automatically moved to specified measurement position using motor and linear guide, the position error of measuring point is smaller when testing, improves test precision and simplifies operation, and can realize the automatic acquisition of sound pressure signal when near-field acoustic holography test.

Description

Technical Field

[0001] This invention relates to a technology in the field of acoustic testing, specifically a four-degree-of-freedom automated acoustic holographic scanning test and analysis system. Background Technology

[0002] The near-field acoustic holography method based on the fundamental solution of spherical functions establishes a mapping relationship between the characteristic decomposition mode of vibration velocity on the structural surface and the distribution mode of the radiated sound field. By identifying the participation coefficient of the radiated sound pressure distribution mode on the measurement surface, the required acoustic physical quantities are directly reconstructed on the structural surface according to the mapping transfer relationship. When reconstructing the sound source using this method, sound pressure data needs to be collected at multiple measurement points on the holographic surface. Existing techniques generally use a microphone array to scan the holographic surface to obtain sound pressure data, but moving the microphone array is often cumbersome, which limits the application of this method. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies that rely on manual calibration before testing, leading to significant detection errors and unsuitability for situations with a large number of measurement points. It proposes a four-degree-of-freedom automated acoustic holographic scanning test and analysis system. This system utilizes a motor and linear guide rails to automatically move a microphone array to a designated measurement position. During testing, the positional error of the measurement points is minimized, improving testing accuracy and simplifying operation. It also enables automated acquisition of sound pressure signals during near-field acoustic holographic testing.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a four-degree-of-freedom automated acoustic holographic scanning test and analysis system, comprising: an acoustic holographic testing platform, a microphone array, a PLC control device, a data acquisition device, and an analysis module. The acoustic holographic testing platform is connected to the PLC control device, and the sound source to be tested is placed on the acoustic holographic testing platform. The microphone array is set on the acoustic holographic testing platform and connected to the data acquisition device. The analysis module determines the measurement position based on the position of the sound source to be tested and the size of the microphone array and outputs the result to the PLC control device. After the PLC control device drives the microphone array to move to the measurement position, the microphone array scans the measurement points on the holographic surface of the object under test. The data acquisition device collects the sound pressure signals of the measurement points, and the analysis module obtains the sound source distribution of the object under test according to the acoustic holographic scanning algorithm.

[0006] The measurement position refers to the position of the microphone circular array in three-dimensional space, where the data acquisition device collects sound pressure data. This position is determined by the location of the sound source under test, the installation position of the microphone circular array in the acoustic holographic test platform, and the order of the fundamental solution of the spherical function.

[0007] The analysis module includes a communication unit, a data acquisition and control unit, and a scanning and measurement unit, wherein: the communication unit outputs measurement position commands and receives sound pressure signals; the data acquisition and control unit controls the data acquisition device; and the scanning and measurement unit calculates the sound source distribution of the object under test according to the acoustic holographic scanning algorithm.

[0008] This invention relates to a four-degree-of-freedom automated acoustic holographic scanning test and analysis method based on the above-mentioned system. First, microphones are set on a microphone circumferential array. Then, the measurement position is written into a PLC control device through an analysis module. The PLC control device then drives the microphone circumferential array to move to the designated measurement position to collect sound pressure data. Specifically, the analysis module automatically calculates the measurement position based on the location of the sound source to be tested, the installation position of the microphone circumferential array in the acoustic holographic test platform, and the order of the fundamental solution of the spherical function. Based on the collected sound pressure data on the holographic surface, the sound source distribution of the object under test is obtained using a near-field acoustic holography method based on the fundamental solution of the spherical function.

[0009] Technical effect

[0010] Compared with existing technologies, this invention avoids the problems of cumbersome operation and low positioning accuracy caused by manually adjusting the microphone array, thus improving testing efficiency and accuracy. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the present invention;

[0012] Figure 2 Axonometric drawing of the acoustic holographic testing platform;

[0013] Figure 3 Axonometric drawing of a circular array of microphones;

[0014] Figure 4 A schematic diagram for calculating the horizontal and vertical positions of the microphone;

[0015] Figure 5 A schematic diagram for calculating the measurement position of a microphone circular array;

[0016] Figure 6 The reconstruction result is shown in the example.

[0017] In the diagram: 1. Sound holographic testing platform; 2. Microphone circumferential array; 3. PLC control device; 4. Data acquisition device; 5. Analysis module; 6. Pulley; 7. Support frame; 8. X-axis sliding guide rail; 9. Slider; 10. Guide rail fixing component; 11. Y-axis transmission device; 12. Belt transmission component; 13. Motor; 14. X-axis transmission device; 15. Y-axis sliding guide rail; 16. Bearing platform; 17. Z-axis transmission device; 18. Z-axis sliding guide rail; 19. Rotating component; 20. Horizontal connecting component; 21. Vertical connecting component; 22. Angle code; 23. Support component; 24. Bracket fixing device; 25. Bracket; 26. Microphone fixing device; 27. Microphone. Detailed Implementation

[0018] like Figure 1 As shown, this embodiment relates to a four-degree-of-freedom automated acoustic holographic scanning test and analysis system, comprising: an acoustic holographic testing platform 1, a microphone array 2, a PLC control device 3, a data acquisition device 4, and an analysis module 5. The acoustic holographic testing platform is connected to the PLC control device, and the sound source to be tested is placed on the acoustic holographic testing platform. The microphone array is set on the acoustic holographic testing platform and connected to the data acquisition device. The analysis module determines the measurement position based on the position of the sound source to be tested and the size of the microphone array and outputs the result to the PLC control device. After the PLC control device drives the microphone array to move to the measurement position, the microphone array scans the measurement points on the holographic surface of the object to be tested. The data acquisition device collects the sound pressure signals of the measurement points, and the analysis module obtains the sound source distribution of the object to be tested according to the acoustic holographic scanning algorithm.

[0019] like Figure 2 As shown, the acoustic holographic testing platform 1 includes: a rectangular support frame 7 and a three-axis transmission mechanism and a carrier platform 16 disposed therein, wherein: the microphone circumferential array 2 is fixedly disposed on the three-axis transmission mechanism to realize three-dimensional movement within the support frame 7, and the carrier platform 16 is fixed to the lower side inside the support frame 7.

[0020] The support frame 7 is equipped with four pulleys 6 at its bottom.

[0021] The three-axis transmission mechanism includes: an X-axis sliding guide rail 8, a slider 9, a guide rail fixing component 10, a Y-axis transmission device 11, a belt transmission component 12, four motors 13, an X-axis transmission device 14, a Y-axis sliding guide rail 15, a support platform 16, a Z-axis transmission device 17, a Z-axis sliding guide rail 18, and a rotating component 19. The X-axis sliding guide rail 8 is fixed to the left and right sides of the top of the support frame 7. The Y-axis sliding guide rail 15 is fixed to the slider on the X-axis sliding guide rail 8 via the guide rail fixing component 10. The belt transmission component 12... The slider of the Z-axis sliding guide 18 is connected and fixed to the slider of the Y-axis sliding guide 15 through the Z-axis transmission device 17. The rotating component 19 is fixed to the bottom of the Z-axis sliding guide 18 and connected to the microphone circumferential array 2. Several motors are fixed on the support frame 7 to drive each slider to translate on the corresponding guide rail and to rotate the rotating component 19. The X-axis transmission device 14 and the Y-axis transmission device 11 are respectively connected to the corresponding motors to transmit motion.

[0022] The four motors 13 are respectively connected to the PLC control device 3 and receive control commands to drive the microphone array to move to the measurement position.

[0023] like Figure 3 As shown, the microphone circumferential array 2 includes: a bracket fixing device 24 and a connecting mechanism disposed thereon, and several sets of microphones 27 with microphone fixing devices 26 and brackets 25, wherein: the brackets 25 are arranged perpendicularly to the bracket fixing device 24, and the connecting mechanism is fixedly connected to the three-axis transmission mechanism.

[0024] Each bracket 25 has a microphone mounting device 26 attached to its end by screws for holding a microphone 27.

[0025] The bracket 25 is movably mounted on the bracket fixing device 24, thereby adjusting the vertical position of the microphone 27. Several evenly distributed circular holes on the bracket 25 can adjust its horizontal position on the bracket fixing device 24, thereby adjusting the horizontal position of the microphone 27. The horizontal position of the microphone 27 can be finely adjusted by adjusting the position of the microphone 27 in the microphone fixing device 26.

[0026] The connecting mechanism includes: a transverse connector 20, a longitudinal connector 21, a corner bracket 22, and a support member 23, wherein: the transverse connector 20 and the longitudinal connector 21 are fixedly connected, the longitudinal connector 21 and the support member 23 are fixedly connected and fixed by the corner bracket 22 with screws and nuts, and the support member 23 and the bracket fixing device 24 are fixed by the corner bracket 22 with screws and nuts.

[0027] like Figure 4As shown, the horizontal and vertical positions of the microphone on the microphone array, i.e., the positions of the microphone on the microphone array, are determined in the following way: First, the angle of the microphone in the circumferential direction is determined according to the Gauss-Legendre quadrature formula. The order of the fundamental solution of the spherical function is taken as N, and the node of the Gauss-Legendre quadrature formula at N ≥ 1 is μ. i (i = 1, 2, ..., N+1, μ) i If ∈[-1, 1]), then the angle θ of the i-th microphone is... i =arccosμ i θ i ∈[0, π], based on the radius R of the holographic surface, the horizontal position u of the microphone in the microphone circular array is obtained. i =Rsinθ i and vertical position v i =R(1-|cosθ) i |).

[0028] The aforementioned acoustic holographic scanning algorithm specifically includes:

[0029] Step S1: As Figure 5 As shown, a coordinate system O-xyz is established with the end of the X-axis sliding guide as the origin. The sound source to be tested is placed on the support platform, and the coordinates of the center of the equivalent sphere source of the sound source to be tested (x, y, z) are calculated based on the position and geometry of the sound source. s y s , z s ).

[0030] Step S2: Determine the horizontal and vertical positions of the microphone on the microphone circular array based on the order of the fundamental solution of the spherical function and the radius of the holographic surface, and set up the microphone.

[0031] Step S3: Set the position of the sound source to be tested, the size of the microphone array, and the order of the fundamental solution of the spherical function. The analysis module calculates the coordinates of the scanning measurement position based on these parameters, and simultaneously sets the data acquisition waiting time for each measurement position, writing it into the PLC control device. Specifically: Figure 5 As shown, the coordinates of the center of the equivalent sphere source of the sound source under test are (x... s y s , z s The horizontal and vertical offsets of the microphone array relative to the rotating component are L1 and L2, respectively. A polar coordinate system is established with the center of the equivalent spherical source of the sound source under test as the origin. When the order of the fundamental solution of the spherical function is N, the coordinates of the i-th measurement position are: in:

[0032] Step S4: The PLC control device controls the microphone array to move sequentially to each measurement position, and the data acquisition device collects data at the measurement position.

[0033] Through specific measurements, the test was conducted in a semi-anechoic chamber, using a cube with a side length of 0.2m as the vibration sound source. Taking the order N = π / 2, the fundamental solution of the spherical function, seven microphones were arranged on a microphone circular array, resulting in 13 measurement positions and a total of 91 measurement points on the holographic surface. After setting the horizontal and vertical offsets of the microphone circular array relative to the rotating component, and the coordinates of the center of the equivalent spherical source, the test device was activated to collect the sound pressure at the measurement points. Using the collected sound pressure data, a reconstruction was performed at 314Hz using the near-field acoustic holography method based on the fundamental solution of the spherical function, yielding the surface normal vibration velocity distribution, as shown below. Figure 6 As shown.

[0034] Compared with existing technologies, when conducting acoustic holographic testing using this invention, the microphone circumferential array can automatically move to the measurement position to collect sound pressure data, which simplifies the operation of acoustic holographic testing to a certain extent. Compared with traditional testing methods, it simplifies the operation process and greatly improves the testing efficiency of acoustic holography.

[0035] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A four degree of freedom automated acoustic holography scanning test analysis system, characterized by, include: The system comprises a sound holographic testing platform, a microphone array, a PLC control device, a data acquisition device, and an analysis module. The sound holographic testing platform is connected to the PLC control device, and the sound source to be tested is placed within the platform. The microphone array is positioned on the platform and connected to the data acquisition device. The analysis module determines the measurement position based on the location of the sound source and the size of the microphone array and outputs this information to the PLC control device. After the PLC control device drives the microphone array to the measurement position, it scans the measurement points on the holographic surface of the object under test using the microphone array. The data acquisition device collects the sound pressure signals from the measurement points, and the analysis module uses a sound holographic scanning algorithm to obtain the sound source distribution of the object under test. The acoustic holographic testing platform includes: a rectangular support frame, a three-axis transmission mechanism and a carrier platform disposed therein, wherein: a microphone circumferential array is fixedly mounted on the three-axis transmission mechanism to realize three-dimensional movement within the support frame, and the carrier platform is fixed to the lower side inside the support frame; The microphone circumferential array includes: a bracket fixing device and a connecting mechanism disposed thereon, and several sets of microphones with microphone fixing devices and brackets, wherein: the brackets are arranged perpendicularly to the bracket fixing device, and the connecting mechanism is fixedly connected to the three-axis transmission mechanism. The three-axis transmission mechanism includes: an X-axis sliding guide rail, a slider, a guide rail fixing component, a Y-axis transmission device, a belt transmission component, four motors, an X-axis transmission device, a Y-axis sliding guide rail, a support platform, a Z-axis transmission device, a Z-axis sliding guide rail, and a rotating component. Specifically: the X-axis sliding guide rail is fixed to the left and right sides of the top of the support frame; the Y-axis sliding guide rail is fixed to the slider on the X-axis sliding guide rail via the guide rail fixing component; the belt transmission component is respectively located at both ends of the X-axis and Y-axis sliding guide rails; the slider of the Z-axis sliding guide rail is connected and fixed to the slider of the Y-axis sliding guide rail via the Z-axis transmission device; the rotating component is fixed to the bottom of the Z-axis sliding guide rail and connected to the microphone circumferential array; several motors are fixed on the support frame to drive the translation of each slider on the corresponding guide rail and the rotation of the rotating component; the X-axis and Y-axis transmission devices are respectively connected to the corresponding motors for transmitting motion. Each bracket has a microphone mounting device attached to its end by screws for holding the microphone. The bracket is movably mounted on the bracket fixing device to adjust the vertical position of the microphone. Several evenly distributed circular holes on the bracket can adjust its horizontal position on the bracket fixing device, thereby adjusting the horizontal position of the microphone. By adjusting the position of the microphone in the microphone fixing device, the horizontal position of the microphone can be finely adjusted. The connecting mechanism includes: a transverse connector, a longitudinal connector, a corner bracket, and a support member, wherein: the transverse connector and the longitudinal connector are fixedly connected, the longitudinal connector and the support member are fixedly connected and fixed by the corner bracket with screws and nuts, and the support member and the bracket fixing device are fixed by the corner bracket with screws and nuts; The horizontal position and vertical position of the microphone on the microphone circumferential array are as follows: first, the angle of the microphone in the circumferential direction is determined according to the Gauss-Legendre quadrature formula, the order of the basic solution of the spherical function is taken as , , the node of the Gauss-Legendre quadrature formula of the point is , the angle of the first microphone is , , , the radius of the holographic surface is , and the horizontal position and the vertical position of the microphone in the microphone circumferential array are obtained.

2. The four-degree-of-freedom automated acoustic holographic scanning test and analysis system according to claim 1, characterized in that, The aforementioned acoustic holographic scanning algorithm specifically includes: Step S1: Establish a coordinate system with the end of the X-axis sliding guide as the origin. The sound source to be tested is placed on the support platform, and the coordinates of the center of the equivalent spherical source of the sound source to be tested are calculated based on the position and geometry of the sound source. ; Step S2: Determine the horizontal and vertical positions of the microphone on the microphone circular array based on the order of the fundamental solution of the spherical function and the radius of the holographic surface, and set up the microphone. Step S3: Set the position of the sound source to be tested, the size of the microphone array, and the order of the fundamental solution of the spherical function. The analysis module calculates the coordinates of the scanning measurement position based on these parameters, and sets the data acquisition waiting time for each measurement position, which is then written into the PLC control device. Specifically, as shown in Figure 5, the coordinates of the center of the equivalent spherical source of the sound source to be tested are: The horizontal and vertical offsets of the microphone array relative to the rotating component are respectively , A polar coordinate system is established with the center of the equivalent spherical source of the sound source under test as the origin. When the order of the fundamental solution of the spherical function is... At that time, the first The coordinates of each measurement location are: ,in: , ; Step S4: The PLC control device controls the microphone array to move sequentially to each measurement position, and the data acquisition device collects data at the measurement position.

3. A four-degree-of-freedom automated acoustic holographic scanning test and analysis method based on the system described in claim 1 or 2, characterized in that, First, microphones are set up on a microphone array. Then, the measurement position is written into the PLC control device through the analysis module. The PLC control device then drives the microphone array to move to the designated measurement position to collect sound pressure data. Specifically: the analysis module ① automatically calculates the measurement position based on the position of the sound source to be tested, the installation position of the microphone array in the acoustic holographic test platform, and the order of the fundamental solution of the spherical function; ② based on the sound pressure data collected on the holographic surface, the sound source distribution of the object under test is obtained using the near-field acoustic holography method based on the fundamental solution of the spherical function.

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