Micro-vibration real-time measurement method based on mobile phone sound signals

Abstract

The invention discloses a micro-vibration real-time measurement method based on mobile phone sound signals. According to the method, a customized linear frequency modulation signal is emitted by using a mobile phone loudspeaker, and a top microphone and a bottom microphone respectively receive a return signal; selecting a frame signal from each of the two return signals, extracting a plurality of sub-frame signals, and sequentially performing frequency mixing and orthogonal decomposition on the sub-frame signals to obtain an initial phase and a selected phase; and then a part of subframes are filtered out through dual-channel noise signal elimination and a circle fitting algorithm, phase points after correction of the remaining subframes are obtained through least square fitting correction, and vibration displacement of a vibration object is obtained through processing. The micro-vibration real-time measurement method based on the mobile phone sound signals has the advantages of being simple in deployment, low in cost and portable, is particularly suitable for light blocking conditions or complex industrial scenes with smoke shielding, and therefore has wide application prospects in the fields of security inspection, industrial detection and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of distance measurement, and in particular relates to a real-time micro-vibration measurement method based on mobile phone acoustic signals. Background Art

[0002] With the development of economy and technology, the country's demand for detecting the status of industrial equipment is becoming more and more urgent. Vibration measurement is an important indicator of the status of industrial equipment. How to accurately obtain the vibration information of industrial equipment has become an urgent problem to be solved. The existing vibration measurement methods have their own advantages and disadvantages:

[0003] Piezoelectric accelerometer solution: It is the most common and mature contact vibration measurement solution, which uses small acceleration changes to calculate the amplitude of vibration. However, this solution is complex to deploy and obtain data. It requires placing sensors at multiple locations on industrial equipment and obtaining vibration information through a host computer. ;

[0004] LiDAR solution: High-precision LiDAR is the mainstream non-contact vibration measurement method. However, due to its high cost, common transparent obstacles or reflective objects in industrial scenes will seriously affect the measurement accuracy of LiDAR, resulting in significantly increased errors;

[0005] Visual solution: Visual sensors have become a popular vibration measurement method due to their moderate cost and convenient data acquisition. However, environmental factors such as light and occlusion can greatly interfere with the accuracy of visual measurement methods. At the same time, due to the complexity of industrial scenarios, higher requirements are placed on the deployment of visual cameras.

[0006] Radio frequency identification (RFID) solution: The vibration detection method based on radio frequency signals is a moderately cost-effective solution. However, this solution requires vibration measurement through two devices, tags and readers. The deployment is more complicated than other solutions and has greater restrictions on industrial scenarios.

[0007] Millimeter-wave radar: Millimeter-wave radar is a popular vibration measurement method, which can achieve micron-level vibration measurement accuracy under ideal conditions. However, the cost of millimeter-wave radar base stations is high, and the accuracy will drop significantly when the signal is blocked. Summary of the invention

[0008] In view of the above problems existing in the prior art, the present invention provides a real-time micro-vibration measurement method based on mobile phone acoustic signals, which can realize a high-precision vibration measurement method in industrial scenarios without the need to deploy equipment in advance.

[0009] The present invention adopts the following technical solutions:

[0010] The real-time micro-vibration measurement method based on mobile phone acoustic signals of the present invention comprises:

[0011] Step (1): The speaker of the mobile phone transmits a linear frequency modulation signal to the vibrating object as a transmission signal, and the bottom microphone and the top microphone of the mobile phone respectively receive the transmission signal as a return signal;

[0012] Step (2): performing separation processing on the return signal to obtain a subframe signal and a subframe pair signal;

[0013] Step (3): for the subframe signal and the subframe pair signal combined with the transmission signal, the signal analysis and calculation processing are sequentially performed including mixing, orthogonal decomposition, phase extraction, filtering, screening, fitting and correction to obtain the real-time vibration displacement of the vibrating object.

[0014] The step (2) specifically comprises: selecting a segment of the return signal received from the microphones at the bottom and top of the mobile phone as a frame signal in real time, extracting a plurality of subframe signals with different initial frequencies and start times from each frame signal, and forming a group of subframe pair signals from a subframe signal extracted from each of the two frame signals and having the same initial frequency;

[0015] The step (3) is specifically:

[0016] Step (3.1): Mix each subframe signal with the transmission signal to obtain a mixed signal of each subframe signal;

[0017] Step (3.2): orthogonally decompose the mixing signal of each subframe and filter the high-frequency band to obtain the initial phase of each mixing signal, and then extract M-1 phases from each mixing signal in sequence at a certain time interval starting from the initial phase, and mark all phases in the form of phase points on the phase diagram as phase points of the subframe signal, where M represents the number of phases extracted from the mixing signal of each subframe signal;

[0018] Step (3.3): All phase points of each subframe signal on the phase diagram are connected in sequence according to the order extracted in step (3.2), and the connecting lines between all phase points in a subframe signal form a broken line trajectory that is approximately a circular arc on the phase diagram;

[0019] Step (3.4): Based on the difference L between the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the top microphone and the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the bottom microphone k Processing to obtain a fixed phase difference Δθ k , using a fixed phase difference Δθ k Filter all subframe signals to filter out the subframe signals whose phase difference between the two subframe signals is not equal to the fixed phase difference Δθ k A set of subframe pair signals;

[0020] Step (3.5): Generate a fitting circle using a circle fitting algorithm based on the broken line trajectory of the remaining subframes filtered in step (3.4) in the phase diagram, and then filter out abnormal subframe signals based on the distance relationship between the broken line trajectory and the center of the fitting circle and the radius of the fitting circle to obtain a filtered subframe signal;

[0021] Step (3.6): Use the least square method to perform fitting correction on the broken line trajectory of the screened subframe signal to obtain the corrected phase point;

[0022] Step (3.7): Obtain the phase difference between two adjacent subframe signals according to the corrected phase point, and then determine the vibration direction of the vibrating object according to the positive or negative sign of the phase difference;

[0023] Step (3.8): Based on the corrected phase point and the initial frequency of the screened subframe signal, the vibration displacement distance of the vibrating object is processed, and then combined with the vibration direction, the real-time vibration displacement of the vibrating object within the starting time difference of two adjacent subframe signals is obtained.

[0024] The vibrating object described in the present invention may generally be an industrial equipment or instrument, but is not limited thereto.

[0025] Furthermore, the solution of the present invention requires that the mobile phone be provided with microphones at both the bottom and the top.

[0026] The transmission signal in step (1) is set according to the following formula:

[0027]

[0028] Among them, f min Represents the minimum frequency of the transmitted signal, t represents the time, T represents the period of the transmitted signal, t∈[0,T], B represents the bandwidth of the transmitted signal, and s(t) represents the transmitted signal at time t.

[0029] In the step (2), several signals are extracted from two frame signals at fixed time intervals, and the initial frequency of each extracted signal is adjusted according to a fixed frequency interval to obtain several subframe signals with different initial frequencies, and the time interval and frequency interval of the two frame signals are the same.

[0030] The two adjacent subframe signals in the step (3.7) and the step (3.8) refer to the subframe signal and the subframe signal extracted next in the extraction order.

[0031] The fixed phase difference Δθ in step (3.4) k It is obtained according to the following formula:

[0032]

[0033] Among them, fmin Indicates the minimum frequency of the transmitted signal, L k It indicates the difference between the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the top microphone and the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the bottom microphone.

[0034] In the step (3.5), the abnormal subframe signal is specifically filtered out by the following formula:

[0035]

[0036] Where K is the subframe signal abnormality parameter, which is used to determine whether the subframe signal is an abnormal subframe signal, and R C Indicates the radius of the fitting circle, Z C represents the coordinates of the center of the fitting circle on the phase diagram, Indicates subframe signal s x,y The coordinates of the mth phase point on the phase diagram.

[0037] In the step (3.7), the phase difference between two adjacent subframe signals is specifically obtained by the following formula:

[0038]

[0039] In the formula, Δθ x,y Indicates the phase difference, I x,y and Q x,y Represents subframe signal s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram, where Δθ x,y The x in the figure represents the order of the subframe signals between the subframe signals separated by the same frame signal, Δθ x,y The values ​​of y in can be 1 and 2, which correspond to the subframe signals in the frame signals selected from the return signals received by the microphones at the bottom and top of the mobile phone respectively;

[0040] In the step (3.8), the vibration displacement distance Δd of the vibrating object is specifically obtained by the following formula:

[0041]

[0042] In the formula, f x,y Indicates subframe signal s x,y The initial frequency, c represents the speed of sound in air, I x,y and Q x,y Represents subframe signal s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram.

[0043] The beneficial effects of the present invention are:

[0044] 1. The invention adopts a customized signal in the range of 17kHz-22kHz as an excitation signal, which can reduce interference to humans on the one hand, and reduce the influence of low-frequency noise of industrial equipment on vibration detection on the other hand.

[0045] 2. The present invention utilizes the dual microphone characteristics of the mobile phone to filter and process noise signals and multipath signals, and can achieve high-precision vibration detection in complex industrial scenarios. Combined with the least squares method, the influence of factors such as slight shaking of the human hand on micro-vibration measurement can be further reduced.

[0046] 3. The real-time micro-vibration measurement method based on mobile phone acoustic signals proposed in the present invention has the advantages of simple deployment, low cost and portability. It is particularly suitable for complex industrial scenes with light blocking conditions or smoke obstruction. Therefore, the present invention has broad application prospects in security inspection, industrial inspection and other fields.

[0047] 4. The present invention integrates a portable mobile phone with a vibration measurement solution based on acoustic signals, thereby avoiding the complexity of equipment deployment and the influence of environmental factors such as occlusion caused by early equipment deployment, and provides a low-cost and portable mobile vibration measurement solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a flow chart of the real-time micro-vibration measurement method based on mobile phone acoustic signals of the present invention;

[0050] Figure 2 It is a schematic diagram of the vibration measurement principle;

[0051] Figure 3 is the actual noise spectrum;

[0052] Figure 4 It is a schematic diagram of the fixed distance difference of the dual channels of a mobile phone;

[0053] Figure 5 It is a schematic diagram of circle fitting to remove noise;

[0054] Figure 6 It is a schematic diagram of the relationship between vibration direction and phase change.

[0055] Figure 7 This is a graph of real-time measurement results of micro-vibration in actual industrial scenarios.

[0056] Figure 8 This is the micro-vibration error result diagram in the actual scene. DETAILED DESCRIPTION

[0057] The following describes the embodiments of the present invention through specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0058] like Figure 1 As shown, the specific embodiment of the micro-vibration real-time measurement method of the present invention includes the following steps:

[0059] Step (1): The speaker of the smartphone transmits a linear frequency modulation signal as a transmission signal to the vibrating object, and the transmission signal is received by the bottom microphone and the top microphone of the smartphone as a return signal, respectively. The return signal includes a direct signal, an echo signal and a noise signal. The echo signal is a signal received by the smartphone microphone after the transmitted linear frequency modulation signal returns from the vibrating object;

[0060] The transmit signal is set according to the following formula:

[0061]

[0062] Among them, f min represents the minimum frequency of the transmitted signal, t represents the time, T represents the period of the transmitted signal, t∈[0,T], B represents the bandwidth of the transmitted signal, and s(t) represents the transmitted signal at time t. In this embodiment, the bandwidth B of the signal is 5kHz, the period T is 50ms, and the minimum frequency f min The acoustic signal selects a linear sweep signal with an inaudible frequency band and good correlation, whose frequency changes linearly with time. This signal not only has good correlation, but also is the signal frequency band least affected by low-frequency noise in industrial scenarios among the frequency bands that can be selected by mobile phones.

[0063] Step (2): performing separation processing on the return signal to obtain a subframe signal and a subframe pair signal;

[0064] Step (2): Specifically, a segment of the signal is selected from the return signals received from the microphones at the bottom and top of the smartphone in real time as a frame signal, and a filter is used to extract a number of subframe signals with different initial frequencies and start times from each frame signal. A subframe pair signal is formed by extracting a subframe signal from each of the two frame signals and having the same initial frequency; the duration of the frame signal is the period of a linear frequency modulation signal, and the start time of the two frame signals is the same.

[0065] Among them, several signals are extracted from two frame signals at a fixed time interval, and the initial frequency of each extracted signal is adjusted according to a fixed frequency interval to obtain several subframe signals s with different initial frequencies. x,y , and the time interval and frequency interval of the two frame signals are the same.

[0066] The time interval controls the start time of the subframe signal, and the frequency interval controls the initial frequency of the subframe signal. The separation operation distributes the signal to a time-frequency grid according to these two conditions. The frequency and time range of adjacent subframe signals overlap partially. The fixed time interval is the start time difference between two adjacent subframe signals, and the frequency span of each subframe signal is the same, that is, the frequency span from the initial frequency to the end frequency of the subframe signal is a fixed value.

[0067] like Figure 2 As shown, in this embodiment, a filter is used to decompose a 50ms frame signal with a frequency band of 17kHz-22kHz into four 20ms, 2kHz bandwidth subframe signals.

[0068] Step (3): for the subframe signal and the subframe pair signal combined with the transmission signal, the signal analysis and calculation processing are sequentially performed including mixing, orthogonal decomposition, phase extraction, filtering, screening, fitting and correction to obtain the real-time vibration displacement of the vibrating object.

[0069] Step (3) is specifically as follows:

[0070] Step (3.1): Use the frequency modulated continuous wave method for each subframe signal, mix each subframe signal with the transmission signal to obtain the mixed signal of each subframe signal; specifically, extract the linear frequency modulation signal of the same time period and frequency band as each subframe signal from the transmission signal, and then mix it with the subframe signal to obtain the mixed signal. The direct signal frequency and the echo signal frequency are processed, and then the reference distance between the corresponding smartphone and the vibrating object is obtained through conversion processing, and it is determined whether the reference distances obtained by all subframe signals are equal. If they are equal, the following operations are performed.

[0071] The reference distance is obtained according to the following formula:

[0072]

[0073] Where f1 is the frequency component of the first peak, f t is the frequency component of the highest peak after the first peak, f s is the sampling rate of the signal, FFT Len is the length of the fast Fourier transform, T is the periodic signal of the customized signal, B is the bandwidth of the customized signal, c is the speed of sound, and R is the reference distance.

[0074] Step (3.2): the mixing signal of each subframe is subjected to orthogonal decomposition processing and the high-frequency band is filtered through a filter to obtain the initial phase of each mixing signal, and then M-1 phases are extracted from each mixing signal in sequence at a certain time interval starting from the initial phase, and all phases are marked in the form of phase points on a previously blank phase diagram as phase points of the subframe signal, where M represents the number of phases extracted from the mixing signal of each subframe signal;

[0075] The orthogonal decomposition is as follows: on the basis of mixing, the beat frequency of the mixing signal is estimated, and the mixing signal can be expressed as:

[0076]

[0077] In the formula, α i , f i ,θ i They represent the signal attenuation coefficient, beat frequency and initial phase of the i-th path respectively, and N represents the number of paths. In the frequency modulated continuous wave scheme, the beat frequency of the corresponding vibration object reflected signal path can be calculated by the difference frequency: The beat frequency is used to perform orthogonal decomposition on the mixed signal, and then the high-frequency band is filtered through a filter to obtain the initial phase data of the reflected signal of the vibrating object, that is, and Where I is the horizontal coordinate and Q is the vertical coordinate. In the phase diagram, a circular arc information representing the initial phase can be shown.

[0078] Step (3.3): All phase points of each subframe signal on the phase diagram are connected in sequence according to the order extracted in step (3.2), and the connecting lines between all phase points in a subframe signal form a broken line trajectory that is approximately an arc on the phase diagram, and a broken line trajectory consists of M phase points;

[0079] Step (3.4): Based on the difference L between the distance the transmitted signal passes through the smartphone speaker and is reflected by the vibrating object to the top microphone and the distance the transmitted signal passes through the smartphone speaker and is reflected by the vibrating object to the bottom microphone k Get a fixed phase difference Δθ k , using a fixed phase difference Δθ k The filtering operation is performed on all subframe signals.

[0080] like Figure 4 As shown, the distance difference L k The specific information is obtained according to the following announcement:

[0081]

[0082] Among them, L1 represents the distance from the smartphone speaker to the bottom microphone, L2 represents the distance from the smartphone speaker to the top microphone, and L3 represents the distance between the bottom microphone and the top microphone of the smartphone.

[0083] Fixed phase difference Δθ k It is obtained according to the following formula:

[0084]

[0085] Among them, unwrap is the unwrap function, f min Indicates the minimum frequency of the transmitted signal, L k It represents the difference between the distance of the transmitted signal reflected from the smartphone speaker to the top microphone and the distance of the transmitted signal reflected from the smartphone speaker to the bottom microphone. The unwrap function solves the phase singularity problem. The known phase difference is used to process the broken line trajectory of the same subframe signal in the phase diagram under dual channels, and the broken line trajectory corresponding to the subframe signal that cannot achieve micro-vibration measurement due to low signal-to-noise ratio is filtered out.

[0086] In step (3.4), a fixed phase difference Δθ is used k Filter all subframe signals to filter out the subframe signals whose phase difference between the two subframe signals is not equal to the fixed phase difference Δθ k A set of subframe pairs of signals, through a fixed phase difference Δθ k Filter out interference signals;

[0087] Step (3.5): Generate a fitting circle using a circle fitting algorithm based on the broken line trajectory of the remaining subframes filtered in step (3.4) in the phase diagram, and then filter out abnormal subframe signals based on the distance relationship between the broken line trajectory and the center of the fitting circle and the radius of the fitting circle to obtain a filtered subframe signal;

[0088] like Figure 5 As shown, a circle fitting is performed on the arcs of all sub-frame signals in the same frame signal under dual channels on the phase diagram.

[0089] In step (3.5), the abnormal subframe signal is filtered out by the following formula:

[0090]

[0091] Where K is the subframe signal abnormality parameter, which is used to determine whether the subframe signal is an abnormal subframe signal, and R C Indicates the radius of the fitting circle, Z C represents the coordinates of the center of the fitting circle on the phase diagram, P xm,y Indicates subframe signal s x,y The coordinates of the mth phase point on the phase diagram.

[0092] The distance relationship between the arc trajectory and the center of the fitting circle is the distance relationship between all phase points in the broken line trajectory and the center of the fitting circle. 0.5 is the threshold. When K>0.5, the corresponding subframe signal is filtered out, that is, the arc with a maximum or minimum distance to the center of the fitting circle, that is, the vibration signal received from other reflecting objects in the industrial scene, and the arc corresponding to the subframe signal that cannot achieve micro-vibration measurement due to the influence of multipath signals is eliminated.

[0093] Step (3.6): Use the least square method to perform fitting correction on the broken line trajectory of the screened subframe signal to obtain the corrected phase point;

[0094] like Figure 3 As shown in the figure, there are strong noise and serious multipath signals in industrial scenes, and incorrect identification signals can easily affect the measurement results of micro-vibration. By obtaining the broken line trajectory of each subframe signal on the phase diagram under the dual-channel of the mobile phone, combined with the fixed phase difference between the two channels, the noise signal that actually affects the micro-vibration measurement is eliminated, and the arcs of multiple subframe signals in the same frame signal on the phase diagram are fitted with circles to eliminate the multipath signals that affect the micro-vibration measurement, and the arcs of all subframe signals on the phase diagram are optimized by the least squares method to correct the influence of slight shaking of the human hand on the micro-vibration measurement.

[0095] The least squares correction is as follows: the phase deviation caused by the change in arc radius caused by unrelated motion is weaker than vibration. The arcs on the phase diagram in each subframe are corrected so that they fall on arcs with the same radius. This correction is a linear transformation process. The reference formula is as follows:

[0096]

[0097] In the formula, and Represents the horizontal and vertical coordinates of the corrected center of the circle on the phase diagram, Indicates the radius after correction. A is an M×3 matrix, B is an M×1 matrix, and C is an M×M matrix, where M is the number of sample points in the arc on the phase map. Specifically, it can be expressed as:

[0098]

[0099] In the formula, |s x,y,m | represents the mth sample point of the yth channel signal in the xth subframe signal within the arc on the phase diagram, |s x,y,m | X and |s x,y,m | Y Respectively represent the horizontal and vertical coordinates of the sample point on the phase diagram, and I represents the unit matrix. Each sample is individually mapped to the project arc through the result of least squares estimation to reduce the influence of irrelevant motion on micro-vibration measurement.

[0100] Step (3.7): Set the direction away from the smartphone as the positive direction, obtain the phase difference between two adjacent subframe signals according to the corrected phase point, and then determine the vibration direction of the vibrating object according to the positive or negative phase difference;

[0101] The phase difference between two adjacent subframe signals is specifically obtained by the following formula:

[0102]

[0103] In the formula, Δθ x,y Indicates the phase difference, I x,y and Q x,y Represents subframe signal s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram are generally and The mean of the coordinates of the phase points or Phase point coordinates, where Δθ x,y The x in the figure represents the order of the subframe signals between the subframe signals separated by the same frame signal, Δθ x,y The values ​​of y in the figure can be 1 and 2, which correspond to the subframe signals in the frame signals selected from the return signals received by the microphones at the bottom and top of the smartphone, respectively; the x and y at other positions in the present invention are explained in the same way.

[0104] The phase points in step (3.7) and step (3.8) are all corrected phase points.

[0105] Step (3.8): Based on the corrected phase point and the initial frequency of the screened subframe signal, the vibration displacement distance of the vibrating object is processed, and then combined with the vibration direction, the real-time vibration displacement of the vibrating object within the starting time difference of two adjacent subframe signals is obtained, so as to realize real-time vibration tracking and perform real-time vibration measurement on vibrating objects in actual industrial scenarios.

[0106] The vibration displacement distance of the vibrating object is specifically obtained by the following formula:

[0107]

[0108] In the formula, f x,y Indicates subframe signal s x,y The initial frequency, c represents the speed of sound in air, I x,y and Q x,y Represents subframe signal s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram are generally and The mean of the coordinates of the phase points or The coordinate values ​​of each phase point and the distance of vibration displacement are all based on the vibration position obtained by calculation in the previous subframe as a reference.

[0109] In step (3.7) and step (3.8), the two adjacent subframe signals refer to the subframe signal and the next subframe signal extracted according to the extraction order. That is, the subframe signal and the next subframe signal with the smallest time interval are the two adjacent subframe signals.

[0110] refer to Figure 7 , which is a graph showing the real-time measurement results of micro-vibrations of normal and abnormal industrial equipment in actual industrial scenarios using the method in this example.

[0111] refer to Figure 8 As shown, this is a diagram of the vibration measurement error achieved by the method in this example on normal industrial equipment in an actual industrial scenario.

[0112] The error results of measuring vibration on normal industrial equipment in industrial scenarios are: 0.3872mm when compared to the vibrating object at 0.3m; 0.4889mm when compared to the vibrating object at 0.5m; 0.6289mm when compared to the vibrating object at 1m. It can be seen that the real-time micro-vibration measurement method based on smartphone acoustic signals has achieved sub-millimeter vibration measurement in industrial scenarios, which is no less than the solution that requires advance deployment and label information.

[0113] The vibrating object described in the present invention can generally be an industrial equipment instrument. In this embodiment, the engine of a small ship is tested, but it is not limited to this.

[0114] Furthermore, the solution of the present invention requires that the mobile phone be provided with microphones at both the bottom and the top.

[0115] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope of the present invention.

Claims

1. A real-time measurement method of micro-vibration based on mobile phone acoustic signals, characterized in that: Includes steps: Step (1): The speaker of the mobile phone transmits a linear frequency modulation signal to the vibrating object as a transmission signal, and the bottom microphone and the top microphone of the mobile phone respectively receive the transmission signal as a return signal; Step (2): performing separation processing on the return signal to obtain a subframe signal and a subframe pair signal; Step (3): for the subframe signal and the subframe pair signal combined with the transmission signal, the signal analysis and calculation processing are sequentially performed including mixing, orthogonal decomposition, phase extraction, filtering, screening, fitting and correction to obtain the real-time vibration displacement of the vibrating object.

2. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 1, characterized in that: The step (2) is specifically as follows: a segment of the signal is selected from the return signals received from the microphones at the bottom and top of the mobile phone in real time as a frame signal, and a plurality of subframe signals with different initial frequencies and start times are extracted from each frame signal. A subframe signal with the same initial frequency extracted from each of the two frame signals is used to form a group of subframe pair signals.

3. The real-time micro-vibration measurement method based on mobile phone acoustic signals according to claim 1 is characterized in that: The step (3) is specifically: Step (3.1): Mix each subframe signal with the transmission signal to obtain a mixed signal of each subframe signal; Step (3.2): orthogonally decompose the mixing signal of each subframe and filter the high-frequency band to obtain the initial phase of each mixing signal, and then extract M-1 phases from each mixing signal in sequence at a certain time interval starting from the initial phase, and mark all phases in the form of phase points on the phase diagram as phase points of the subframe signal, where M represents the number of phases extracted from the mixing signal of each subframe signal; Step (3.3): All phase points of each subframe signal on the phase diagram are connected in sequence according to the order extracted in step (3.2), and the connecting lines between all phase points in a subframe signal form a broken line trajectory that is approximately a circular arc on the phase diagram; Step (3.4): The fixed phase difference Δθ is obtained based on the difference L between the distance of the transmitted signal passing through the mobile phone speaker and reflected by the vibrating object to the top microphone and the distance of the transmitted signal passing through the mobile phone speaker and reflected by the vibrating object to the bottom microphone. k , using a fixed phase difference Δθ k Filter all subframe signals to filter out the subframe signals whose phase difference between the two subframe signals is not equal to the fixed phase difference Δθ k A set of subframe pair signals; Step (3.5): Generate a fitting circle using a circle fitting algorithm based on the broken line trajectory of the remaining subframes filtered in step (3.4) in the phase diagram, and then filter out abnormal subframe signals based on the distance relationship between the broken line trajectory and the center of the fitting circle and the radius of the fitting circle to obtain a filtered subframe signal; Step (3.6): Use the least square method to perform fitting correction on the broken line trajectory of the screened subframe signal to obtain the corrected phase point; Step (3.7): Obtain the phase difference between two adjacent subframe signals according to the corrected phase point, and then determine the vibration direction of the vibrating object according to the positive or negative sign of the phase difference; Step (3.8): Based on the corrected phase point and the initial frequency of the screened subframe signal, the vibration displacement distance of the vibrating object is processed, and then combined with the vibration direction, the real-time vibration displacement of the vibrating object within the starting time difference of two adjacent subframe signals is obtained.

4. The real-time micro-vibration measurement method based on mobile phone acoustic signals according to claim 1 is characterized in that: The transmission signal in step (1) is set according to the following formula: Among them, f min Represents the minimum frequency of the transmitted signal, t represents the time, T represents the period of the transmitted signal, t∈[0,T], B represents the bandwidth of the transmitted signal, and s(t) represents the transmitted signal at time t.

5. The real-time micro-vibration measurement method based on mobile phone acoustic signals according to claim 2 is characterized in that: In the step (2), several signals are extracted from two frame signals at fixed time intervals, and the initial frequency of each extracted signal is adjusted according to a fixed frequency interval to obtain several subframe signals with different initial frequencies, and the time interval and frequency interval of the two frame signals are the same.

6. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 4, characterized in that: The two adjacent subframe signals in the step (3.7) and the step (3.8) refer to the subframe signal and the subframe signal extracted next in the extraction order.

7. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 3, characterized in that: The fixed phase difference Δθ in step (3.4) k It is obtained according to the following formula: Among them, f min Indicates the minimum frequency of the transmitted signal, L k It indicates the difference between the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the top microphone and the distance that the transmitted signal passes through the mobile phone speaker and is reflected by the vibrating object to the bottom microphone.

8. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 1, characterized in that: In the step (3.5), the abnormal subframe signal is specifically filtered out by the following formula: Where K is the subframe signal abnormality parameter, which is used to determine whether the subframe signal is an abnormal subframe signal, and R C Indicates the radius of the fitting circle, Z C represents the coordinates of the center of the fitting circle on the phase diagram, P xm,y Indicates subframe signal s x,y The coordinates of the mth phase point on the phase diagram.

9. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 3, characterized in that: In the step (3.7), the phase difference between two adjacent subframe signals is specifically obtained by the following formula: In the formula, Δθ x,y Indicates the phase difference, I x,y and Q x,y Represent subframe signals s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram, where Δθ x,y The x in the figure represents the order of the subframe signals between the subframe signals separated by the same frame signal, Δθ x,y The values ​​of y in are 1 and 2, which correspond to the subframe signals in the frame signals selected from the return signals received by the microphones at the bottom and top of the mobile phone, respectively.

10. The method for real-time measurement of micro-vibration based on mobile phone acoustic signals according to claim 3, characterized in that: In the step (3.8), the vibration displacement distance Δd of the vibrating object is specifically obtained by the following formula: In the formula, f x,y Indicates subframe signal s x,y The initial frequency, c represents the speed of sound in air, I x,y and Q x,y Represents subframe signal s x,y The horizontal and vertical coordinate values ​​of the phase point selected in the phase diagram.

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