Impact pulse capturing method based on air column resonance principle and acoustic perception technology

Abstract

A method for capturing impact pulses based on the principle of air column resonance and acoustic sensing technology is disclosed. First, a resonant chamber model is designed. Then, an acoustic sensor matching the structure and frequency response requirements of the resonant chamber is selected. Next, a sensor motherboard is designed and manufactured. The acoustic sensor is then integrated onto the motherboard, and the motherboard is connected in series with the resonant chamber structure along the air vent direction to form a gas-filled, airtight chamber. A sensor housing is then manufactured, combining it with the airtight chamber to form an air column resonant acoustic acquisition device. This device is then fixed to the surface of the object being tested to obtain a resonant signal. A filter is constructed using the resonant frequency present in the resonant chamber to enhance the resonant signal through resonant convolution, resulting in an enhanced resonant convolution signal. Envelope analysis is then performed to obtain the impact pulse envelope signal. This invention achieves impact pulse capture in environments with strong background noise by utilizing the principle of air column resonance and acoustic sensing technology, thereby reducing costs.

Description

Technical Field

[0001] This invention relates to the field of signal analysis and processing technology, and in particular to a method for capturing impact pulses based on the principle of air column resonance and acoustic sensing technology. Background Technology

[0002] Impact pulses are a typical signal widely used in acoustic detection, fault diagnosis, and pattern recognition. For rotating machinery, abnormal noises or localized component failures are often accompanied by impact pulse behavior. Accurate detection and identification of impact pulse signals are crucial steps in mechanical fault diagnosis. However, considering signal transmission paths and noise effects, the impact pulses contained in the signals measured by general sensors are often masked by other signals, resulting in extremely low signal-to-noise ratios. Therefore, enhancing and capturing impact pulse signals is essential for rotating machinery fault diagnosis. To improve the ability to capture impact pulse information under background noise in industrial equipment, resonant demodulation technology is mainly used for signal processing both domestically and internationally.

[0003] Traditional resonant demodulators utilize piezoelectric and strain sensors to detect impact information generated by collisions between components in rotating machinery. Their working principle involves amplifying weak impact signals using the resonant response of an electronic resonator to form a resonant waveform, which is then demodulated and its envelope spectrum processed to determine if a fault exists in the rotating machinery. While this technology is mature, it requires an active RC filter circuit, which is expensive, and the electronic components within it are susceptible to temperature and electromagnetic interference from the industrial environment. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide an impact pulse capture method based on the principle of air column resonance and acoustic sensing technology. By using the principle of air column resonance and acoustic sensing technology, impact pulse capture can be achieved in environments with strong background noise. The physical structure of air column resonance is used to replace the traditional electronic resonator, eliminating the electronic resonator components, eliminating the influence of temperature and industrial electromagnetic environment on the resonator, reducing cost, and can be widely used in the fields of acoustic detection, fault diagnosis and pattern recognition.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for capturing impact pulses based on the principle of air column resonance and acoustic sensing technology includes the following steps:

[0007] Step 1: Based on the pre-designed acoustic sensor, supporting data acquisition, communication circuit structure dimensions and impact pulse convolution inherent frequency requirements, analyze and calculate using 3D modeling software and finite element software to design a resonant chamber model.

[0008] Step 2: Based on the resonant chamber model and the inherent frequency requirement of the impact pulse convolution obtained in Step 1, select an acoustic sensor that matches the resonant chamber structure and frequency response requirements.

[0009] Step 3: Design and manufacture the sensor motherboard based on the resonant cavity structure and the dimensions of the electronic components;

[0010] Step 4: Integrate the acoustic sensor onto the sensor motherboard, open an air hole on the sensor motherboard facing the sound sensor signal receiving end, and connect the sensor motherboard in series with the resonant cavity structure along the direction of the air hole to form an airtight chamber filled with gas.

[0011] Step 5: Design and manufacture the sensor housing according to the circuit board assembly and sensor installation requirements, so that it can be combined with the airtight chamber to form a complete air column resonance acoustic acquisition device.

[0012] Step 6: Fix the air column resonance acoustic acquisition device to the surface of the object being tested, and use the air column resonance principle to realize the convolution of the impact pulse with the resonance frequency of the resonance chamber to obtain the resonance signal x;

[0013] Step 7: Construct a filter based on the resonant frequency present in the resonant cavity to perform resonant convolution feature enhancement on the resonant signal, obtaining the resonant convolution feature enhanced signal x. b ;

[0014] Step 8: Enhance the resonant convolution feature signal x b Envelope analysis was performed to obtain the impact pulse envelope signal x. h .

[0015] Step 1 specifically includes:

[0016] 1.1) Based on the inherent frequency requirement of the impact pulse convolution, the preset resonant frequency of the gas column in the resonant chamber is not lower than f. n ;

[0017] 1.2) Based on the pre-designed acoustic sensor, supporting data acquisition, and communication circuit structure dimensions, design a resonant chamber model using 3D drawing software;

[0018] 1.3) Import the resonant cavity model into the modal analysis module of the finite element analysis software, set the gas properties of the resonant cavity, mesh the resonant cavity, apply boundary conditions to the resonant cavity, and solve for the resonant frequency of the gas column in the resonant cavity.

[0019] 1.4) If the calculation result in step 1.3) is inconsistent with the requirement in step 1.1, optimize the resonant chamber model in step 1.2) and iterate steps 1.2) to 1.3) until the calculation result in step 1.3) is consistent with the requirement in step 1.1), then end the iteration and obtain the optimal resonant chamber model.

[0020] The resonant chamber structure is not limited to regular cavity structures such as cylindrical or conical shapes, or irregular cavity structures; in addition, the material used to manufacture the resonant chamber structure is not limited, and can be metal, plastic, composite material, or coating material.

[0021] The acoustic sensors mentioned are MEMS microphones, electret microphones, etc.

[0022] The gas in the airtight chamber is not limited to air, oxygen, etc.

[0023] The resonant cavity is manufactured by machining, additive manufacturing, or casting molds.

[0024] The resonant frequency of convolution with the impact pulse is not limited to the air column resonant frequency; the resonant frequency originates from the natural frequency of the acoustic sensor or the natural frequency of the sensor motherboard.

[0025] The constructed filter can be a digital filter, an analog filter, or a physical filter designed using mechanical structures.

[0026] The beneficial effects of this invention are as follows: This invention uses an air column resonant cavity to get rid of the dependence of the resonator on electronic components, and has the advantages of being less affected by temperature and electromagnetic environment in industrial sites and having low cost. It can be widely used in the fields of acoustic detection, fault diagnosis and pattern recognition. Attached Figure Description

[0027] Figure 1 The following is a three-view drawing of the irregular resonant chamber structure according to an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the air column resonance acoustic acquisition device according to an embodiment of the present invention.

[0029] Figure 3 The following is a time-domain waveform and spectrum of the impulse response according to an embodiment of the present invention.

[0030] Figure 4 This is the resonant convolution feature enhancement signal in an embodiment of the present invention.

[0031] Figure 5 This is the impact pulse envelope signal in an embodiment of the present invention. Detailed Implementation

[0032] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0033] A method for capturing impact pulses based on the principle of air column resonance and acoustic sensing technology includes the following steps:

[0034] Step 1: Based on the pre-designed acoustic sensor, supporting data acquisition and communication circuit structure dimensions, and the inherent frequency requirements of the impact pulse convolution, a resonant chamber model is designed through analysis and calculation using 3D modeling software and finite element software; specifically:

[0035] 1.1) Based on the inherent frequency requirement of the impact pulse convolution, the first-order resonant frequency of the air column in the resonant chamber is preset to be no less than 5000Hz;

[0036] 1.2) Based on the pre-designed acoustic sensor, supporting data acquisition, and communication circuit structure dimensions, design a resonant chamber model using 3D drawing software, referring to... Figure 1 , Figure 1 These are three views of the resonant chamber in this embodiment. Figure 1 A1 is the main view of the resonant chamber. The outer contour is symmetrical and consists of semicircles and straight lines. There is a through hole with a diameter of 8mm in the middle. Figure 1 B1 is the left view of the resonant chamber, which is obtained by sectional view of the center section AA of the main view; Figure 1 C1 is the top view of the resonant chamber, which is obtained by sectionalizing the main view BB.

[0037] 1.3) Import the resonant cavity model into the modal analysis module of the finite element analysis software, add air as the gas material in the resonant cavity, mesh the resonant cavity, set the inlet end face pressure to 0 MPa, select fully damped solver type, and solve the resonant frequency of the gas column in the resonant cavity, as shown in Table 1.

[0038] Table 1

[0039] order 1 2 3 4 5 6 7 8 9 10 Natural frequency / Hz 5264 5394 10029 15105 18599 21230 22586 24905 25837 27389

[0040] 1.4) The calculation results of the resonant frequency of the air column in the resonant chamber in step 1.3) are consistent with the requirements of step 1.1), thus obtaining the optimal resonant chamber model;

[0041] Step 2: Based on the resonant cavity model and the inherent frequency requirement of the shock pulse convolution obtained in Step 1, select a MEMS microphone that matches the resonant cavity structure and frequency response requirements;

[0042] Step 3: Design and manufacture the sensor motherboard based on the resonant cavity structure and the dimensions of the electronic components;

[0043] Step 4: Integrate the acoustic sensor onto the sensor motherboard, open an air hole on the sensor motherboard facing the sound sensor signal receiving end, and connect the sensor motherboard in series with the irregular resonant chamber structure along the direction of the air hole to form an airtight chamber filled with gas.

[0044] Step 5: Design and manufacture the sensor housing according to the requirements of circuit board assembly and sensor installation, so that it can be combined with the airtight chamber to form a complete air column resonance acoustic acquisition device. See the specific structure below. Figure 2 , Figure 2 The upper and lower housings 1 and 6 are connected by welding. The sensor motherboard 7 inside the housing has an air hole 5. A MEMS microphone 3 is installed above the air hole 5. The air hole 5 is directly connected to the resonant chamber 4 below. The sensor motherboard 7 and the data acquisition circuit board 8 are connected by wires to realize data acquisition. The data acquisition circuit board 8 and the connector 2 are connected by wires to establish a data transmission interface.

[0045] Step 6: Secure the air column resonance acoustic acquisition device to the surface of the object being tested, and strike the sensor housing of the air column resonance acoustic acquisition device with a hammer to obtain the resonance signal, such as... Figure 3 As shown, Figure 3 The above figure shows the time-domain waveform. Figure 3 The following figure shows the frequency domain waveform. Figure 3 The sensor's resonant frequencies (around 5000Hz, 10000Hz, 15000Hz, 18000Hz, 21000Hz, and 26000Hz) can be identified in the spectrum waveform and are basically close to the resonant frequencies of the simulated air column (see Table 1).

[0046] Step 7: Perform bandpass filtering on the resonant signal measured in Step 6. The bandpass filtering frequency range is 24336~28336Hz to obtain the resonant convolution feature enhancement signal, such as... Figure 4 As shown, Figure 4 The display shows that the resonant band filter signal can characterize the impulse response signal with a high signal-to-noise ratio;

[0047] Step 8: Perform a Hilbert transform on the resonant convolution feature enhancement signal to obtain the impulse pulse envelope signal, such as... Figure 5 As shown, Figure 5 The impulse pulse envelope signal after Hilbert transform can be used to further characterize the impulse response signal.

[0048] The beneficial effects of this embodiment are as follows: This invention uses an air column resonant cavity, eliminating the resonator's dependence on electronic components and enabling resonant demodulation of pulse response signals. This method is less affected by temperature and the electromagnetic environment of industrial sites, and is inexpensive. It can be widely used in acoustic testing, fault diagnosis, and pattern recognition.

Claims

1. An impact pulse capturing method based on the principle of air column resonance and acoustic perception technology, characterized in that, Includes the following steps: Step 1: Based on the pre-designed acoustic sensor, supporting data acquisition, communication circuit structure dimensions and impact pulse convolution inherent frequency requirements, analyze and calculate using 3D modeling software and finite element software to design a resonant chamber model. Step 2: Based on the resonant chamber model and the inherent frequency requirement of the impact pulse convolution obtained in Step 1, select an acoustic sensor that matches the resonant chamber structure and frequency response requirements. Step 3: Design and manufacture the sensor motherboard based on the resonant cavity structure and the dimensions of the electronic components; Step 4: Integrate the acoustic sensor onto the sensor motherboard, open an air hole on the sensor motherboard facing the signal receiving end of the acoustic sensor, and connect the sensor motherboard in series with the resonant chamber structure along the direction of the air hole to form an airtight chamber filled with gas. Step 5: Design and manufacture the sensor housing according to the circuit board assembly and sensor installation requirements, so that it can be combined with the airtight chamber to form a complete air column resonance acoustic acquisition device. Step 6: Fix the air column resonance acoustic acquisition device to the surface of the object being tested. Utilize the air column resonance principle to convolve the impact pulse with the resonant frequency of the resonant chamber, thus obtaining the resonance signal. ; Step 7: Construct a filter based on the resonant frequency present in the resonant cavity to perform resonant convolution feature enhancement on the resonant signal, obtaining the resonant convolution feature enhanced signal. ; Step 8, Resonance Convolution Feature Enhancement Signal Performing envelope analysis to obtain an impact pulse envelope signal .

2. The method according to claim 1, characterized in that: Step 1 specifically includes: 1.1) According to the impact pulse convolution inherent frequency requirement, the preset resonance chamber air column resonance frequency is not less than , f n is the first order resonance frequency; 1.2) Based on the pre-designed acoustic sensor, supporting data acquisition, and communication circuit structure dimensions, design a resonant chamber model using 3D drawing software; 1.3) Import the resonant cavity model into the modal analysis module of the finite element analysis software, set the gas properties of the resonant cavity, mesh the resonant cavity, apply boundary conditions to the resonant cavity, and solve for the resonant frequency of the gas column in the resonant cavity. 1.4) If the calculation result in step 1.3) is inconsistent with the requirement in step 1.1, then optimize the resonant chamber model in step 1.2) and iterate from step 1.2) to step 1.3) until the calculation result in step 1.3) is consistent with the requirement in step 1.1), then end the iteration and obtain the optimal resonant chamber model.

3. The method of claim 1, wherein: The resonant chamber model is a regular cavity structure or an irregular cavity structure; the resonant chamber is made of metal, plastic or composite material.

4. The method of claim 1, wherein: The acoustic sensor is a MEMS microphone or an electret microphone.

5. The method of claim 1, wherein: The gas in the airtight chamber is air or oxygen.

6. The method of claim 1, wherein: The resonant cavity is manufactured by machining, additive manufacturing, or mold casting.

7. The method of claim 1, wherein: The resonant frequency of the convolution with the impact pulse is the air column resonant frequency, which originates from the natural frequency of the acoustic sensor or the natural frequency of the sensor motherboard.

8. The method of claim 1, wherein: The constructed filter can be a digital filter, an analog filter, or a physical filter designed using mechanical structures.

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