Active sound wave-based non-metal pipeline depth detection equipment

Abstract

The application discloses active sound wave-based non-metal pipeline buried depth detection equipment and relates to the technical field of pipeline buried depth detection.The application comprises a host computer, a first communication module, a loudspeaker, a piezoelectric integrated circuit sensor, a transmitting end and a receiving end, the transmitting end comprises an acquisition unit, a first single-chip microcomputer and an audio amplifier, the receiving end comprises a second communication module, a second single-chip microcomputer and a digital-to-analog converter, the port of the host computer is connected with the port of the first communication module to establish bidirectional communication, and the output end of the acquisition unit is connected with the input end of the first communication module.The application predicts the interference law by executing an interference analysis process, transmits a detection sound wave in the interval when the interference signal is weak, reduces the influence of the interference signal on the detection result, analyzes the waveform characteristics by executing an interference resistance process, transmits a resistance sound wave to offset the influence of the interference signal, and improves the accuracy of the detection data and the success rate of the detection task execution.

Description

Technical Field

[0001] This invention relates to the field of pipeline burial depth detection technology, specifically to non-metallic pipeline burial depth detection equipment based on active acoustic waves. Background Technology

[0002] The acoustic positioning and detection technology for gas PE pipelines is based on the active sound source detection method, using sound wave propagation as its core technology. It determines the precise location of the target pipeline by analyzing the strength of sound wave attenuation or the time difference of the sensor array. Specifically, the acoustic method involves first using an active sound source transmitter to send detection sound waves into the gas PE pipeline at a specific frequency. The signal propagates directionally along the pipeline through the gas medium. Simultaneously, the sound wave propagates through the pipe wall, vibrating the soil, and reaches the ground. Simultaneously, an active sound source receiver picks up the detection sound waves and captures the signal on the ground. By analyzing the received vibration signals of the same frequency but different intensities, the receiver's built-in chip performs calculations and displays the received signals as sound and a histogram. By continuously receiving sound and the attenuation amplitude of the histogram near the signal point, the vertical disturbance range of the target pipeline is determined, achieving precise horizontal positioning of the pipeline. After locating the pipeline, four IEPE sensors are placed on one side perpendicular to the pipeline to collect acoustic wave data. The sensors are arranged in a four-element array. The host computer calculates the acoustic time difference of the sensors at different locations and then calculates the burial depth value based on the positional relationship of the sensors and the acoustic time difference.

[0003] Non-metallic pipeline burial depth detection equipment is mainly used in various engineering construction sites. However, the construction area is often subject to ground vibration noise generated by the operation of other engineering machinery. When noise and detection sound waves appear simultaneously, they will interfere with the detection results of the detection waves, which can easily lead to deviations in the detection data or failure of the detection mission. Therefore, designing and developing non-metallic pipeline burial depth detection equipment with active sound waves to reduce the influence of noise interference signals is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a non-metallic pipeline burial depth detection equipment based on active acoustic waves, which solves the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a non-metallic pipe burial depth detection equipment based on active acoustic waves, comprising a host computer, a first communication module, a speaker, a piezoelectric integrated circuit sensor, a transmitter, and a receiver. The transmitter includes a data acquisition unit, a first microcontroller, and an audio amplifier. The receiver includes a second communication module, a second microcontroller, and a digital-to-analog converter. The port of the host computer establishes bidirectional communication with the port of the first communication module. The output of the data acquisition unit is connected to the input of the first communication module. The outputs of both the first communication module and the data acquisition unit are connected to the input of the first microcontroller. The output of the first microcontroller is connected to the input of the audio amplifier. The output of the audio amplifier is connected to the input of the speaker. The output of the piezoelectric integrated circuit sensor is connected to the input of the digital-to-analog converter. The output of the digital-to-analog converter is connected to the input of the second microcontroller. The output of the second microcontroller is connected to the input of the second communication module. The output of the second communication module establishes communication with the input of the first communication module via wireless communication.

[0006] The acquisition unit obtains vibration information of the ground where the transmitter is located, marks it as an interference signal, and transmits it to the first microcontroller and the first communication module respectively. The first communication module sends the interference signal back to the host computer. The host computer sends a detection command to the first microcontroller through the first communication module. The first microcontroller sends a first digital signal to the audio amplifier. The audio amplifier amplifies the first digital signal to obtain a first analog signal. The audio amplifier sends the first analog signal to the speaker.

[0007] The loudspeaker converts the first analog signal into a detection sound wave and emits the detection sound wave into the non-metallic pipe. The detection sound wave propagates along the inner axis of the non-metallic pipe through the gas medium inside the non-metallic pipe. The detection sound wave passes through the soil medium and propagates three-dimensionally to the ground through the vibration of the pipe wall of the non-metallic pipe. The piezoelectric integrated circuit sensor acquires the detection sound wave propagating to the ground.

[0008] The piezoelectric integrated circuit sensor converts the acquired sound wave into a second analog signal and transmits it to a digital-to-analog converter. The digital-to-analog converter converts the second analog signal into a second digital signal and transmits it to a second microcontroller. The second microcontroller transmits the second digital signal to a first communication module through a second communication module. The first communication module forwards the second digital signal to a host computer. The host computer executes a signal calculation program based on the first and second digital signals to obtain the positioning depth of the plane where the non-metallic pipe is located.

[0009] Furthermore, before the loudspeaker sends the detection sound wave into the non-metallic pipe, the host computer adjusts the detection command of the first microcontroller according to the interference signal obtained by the acquisition unit.

[0010] The host computer sets a first interference threshold and a second interference threshold. When the interference signal is lower than the first interference threshold, it indicates that there are few interference factors in the detection environment. The host computer executes a normal detection process. The second microcontroller uses a traversal algorithm to solve and filter valid data. When the interference signal is greater than the first interference threshold and less than the second interference threshold, it indicates that there are generally few interference factors in the detection environment. The host computer executes an interference analysis process to obtain the interference pattern of the interference signal and predicts the gaps where the interference signal is weak. The loudspeaker intermittently emits detection sound waves to avoid the influence of the interference signal on the detection sound waves. When the interference signal is greater than the second interference threshold, it indicates that there are many interference factors in the detection environment. At this time, it is necessary to execute an interference resistance process to obtain the waveform characteristics of the interference signal. Based on the waveform characteristics of the interference signal, a resistance sound wave is generated. The resistance sound wave and the normal detection sound wave are frequency-divided and transmitted. Frequency-divided transmission means that different frequencies are used for alternating transmission. The resistance sound wave uses phase cancellation to reduce the influence of the interference signal on the detection sound wave, thereby improving the reliability of the detection data.

[0011] When the piezoelectric integrated circuit sensor collects the sound wave and the second microcontroller transmits the converted second digital signal back to the host computer through the second communication module, the host computer then executes the signal calculation program to obtain the positioning depth of the plane where the non-metallic pipe is located. At this time, the general detection process, interference analysis process, or interference resistance process stops. Regardless of whether it is the general detection process, interference analysis process, or interference resistance process, the signal calculation program needs to be executed to analyze the feedback sound wave after the sound wave is detected.

[0012] Furthermore, the first interference threshold and the second interference threshold are set as follows:

[0013] The host computer continuously acquires and normalizes interference signals from the acquisition unit, marks the maximum value in the interference signal as 1, and converts the remaining interference signals proportionally according to the maximum value. The host computer calculates the average value of all interference signals and extracts the value of the interference signal that appears most frequently as a constant value. The average value and the constant value are used to represent the feature value of the interference signal. Based on the feature value, it is convenient to set the first interference threshold and the second interference threshold.

[0014] The absolute value of the difference between the average value and the constant value of the interference signal calculated by the host computer is marked as the adjustment threshold Ytz. The adjustment threshold is calculated from the average value and the constant value of the interference signal, reflecting the fluctuation degree of the interference signal. It can intuitively reflect the signal interference situation of the current detection environment. The adjustment threshold is used as the smallest adjustment unit for easy reference, and it is also easy to adjust the first interference threshold yz1 and the second interference threshold yz2. One-third of the maximum power of the detection sound wave emitted by the loudspeaker is marked as the initial noise floor Dcs. The initial noise floor Dcs is set to avoid the initial value of the interference signal obtained by the acquisition unit being too small, which would affect the reasonable range of the first interference threshold and the second interference threshold. The power range of the detection sound wave emitted by the loudspeaker is determined by the host computer.

[0015] The host computer follows the formula group The first interference threshold yz1 and the second interference threshold yz2 are calculated, where tj1 is the first adjustment coefficient and tj2 is the second adjustment coefficient.

[0016] Furthermore, during the execution of the general detection process, the host computer sends a detection command to the first microcontroller through the first communication module. The first microcontroller controls the speaker to emit detection sound waves. After receiving the second digital signal, the host computer executes the signal calculation program to perform a traversal algorithm for calculation. The calculation process is as follows:

[0017] The piezoelectric integrated circuit sensor includes a first piezoelectric sensor, a second piezoelectric sensor, a third piezoelectric sensor, and a fourth piezoelectric sensor. These four piezoelectric sensors form a quaternary sensor array. The host computer constructs spatial constraints using the quaternary sensor array, establishes a spherical intersection model for detecting sound waves inside the non-metallic pipe, and preliminarily calculates the positioning depth of the plane containing the non-metallic pipe. The formula set is as follows:

[0018]

[0019] Where x, y, and z are the spatial coordinates of the target point, specifically the spatial coordinates of the sound wave detected by the piezoelectric integrated circuit sensor. x and y form a Cartesian coordinate system, z is the burial depth of the non-metallic pipe, r is the distance from the piezoelectric integrated circuit sensor to the target point, M is the spacing between the first, second, third, and fourth piezoelectric sensors, d12 is the distance difference between the target point and the first and second piezoelectric sensors, d13 is the distance difference between the target point and the first and third piezoelectric sensors, d14 is the distance difference between the target point and the first and fourth piezoelectric sensors, and r1 is the distance from the first piezoelectric sensor to the target point.

[0020] The host computer uses the elimination method to solve the spherical equations simultaneously, corrects the spatial coordinates of the target point, establishes a motion model and predicts the state of the motion model, and combines the second digital signal of the second microcontroller to correct the predicted value and output the positioning depth of the plane where the non-metallic pipe is located.

[0021] Furthermore, during the execution of the interference analysis process, the time window with the weakest interference is predicted, and the loudspeaker is controlled to intermittently emit detection sound waves to avoid interference covering the signal. The unprocessed interference signal is a continuous signal. The host computer splits the interference signal into short frames and the continuous signal into short segments to facilitate the analysis of the time-varying characteristics of the interference. The host computer establishes a signal strength curve, with time on the horizontal axis and the strength value of the interference signal on the vertical axis. The host computer extracts the strength value of the interference signal in each short frame and inputs it into the strength curve to obtain the strength point corresponding to each short frame. The coordinates of the strength point are represented as (Xqd, Yqd), which means that the strength value of the interference signal at time point Xqd is Yqd.

[0022] The host computer uses a fitted curve to connect the intensity points of each short frame. The host computer uses a horizontal line segment to be tangent to each peak and trough of the fitted curve. The intersection of the tangent peaks is marked as the interference point, and the intersection of the tangent troughs is marked as the transmission point.

[0023] The host computer packages all marked interference points and transmission points into a training set. The host computer establishes an ARIMA time series model, inputs the training set into the time series model for training to obtain interference patterns, and determines the time point of sound wave transmission based on the interference patterns.

[0024] The subsequent execution of the signal calculation program by the host computer is consistent with the general detection program, and will not be repeated here. This process yields the positioning depth of the plane where the non-metallic pipe is located during the interference analysis process.

[0025] Furthermore, during the execution of the interference mitigation process, the host computer uses a Fast Fourier Transform to convert the time domain of the interference signal into the frequency domain, as shown in the following formula:

[0026]

[0027] Where q(n) is the time-domain interference signal, i.e., discrete sampling points; Q(m) is the frequency-domain amplitude spectrum, m is the frequency; N is the number of sampling points of the interference signal; e is the natural constant, which facilitates frequency domain analysis of the interference signal; j is the imaginary unit, which is generally used in signal processing in engineering fields to convert the discrete time-domain signal to the frequency domain for analysis and processing through this complex exponential operation, helping to extract features such as frequency, phase, and amplitude of the signal; and j satisfies the condition j 2 =-1;

[0028] The host computer performs phase analysis on the interference signal converted to the frequency domain, and takes the complex argument of the result of the fast Fourier transform to obtain the phase spectrum:

[0029]

[0030] in, Let Re be the phase angle corresponding to frequency m, Re|Q(m)| be the real part in the frequency domain, and Im|Q(m)| be the imaginary part in the frequency domain. By calculating the phase spectrum above, the phase relationship between each frequency of the interference signal can be determined, providing a reference for generating anti-phase waves.

[0031] The host computer performs amplitude estimation on the phase spectrum calculation results. It also calculates the absolute value of the frequency domain amplitude spectrum to obtain the amplitude at each frequency, using the following formula:

[0032] A(m)=|Q(m)|

[0033] Where A(m) is the amplitude corresponding to frequency m. By calculating the amplitude A, the interference intensity of the interference signal can be quantified, thereby determining the amplitude of the resisting sound wave.

[0034] The host computer establishes a feature model and the phase spectrum In the input feature model with amplitude A(m), the waveform characteristics of the interference signal are obtained. The host computer generates an inverted wave based on the waveform characteristics. The host computer sends the inverted wave to the first microcontroller along with the detection command. The first microcontroller sends the resisting sound wave according to the inverted wave. The resisting sound wave and the detection sound wave are sent alternately at different frequencies.

[0035] The subsequent execution of the signal calculation program by the host computer is consistent with the general detection program, and will not be repeated here. This process yields the positioning depth of the plane containing the non-metallic pipe under the interference resistance process.

[0036] Furthermore, the host computer uses the elimination method to solve the spherical equations simultaneously, deriving the spatial coordinates (x, y, z) of the target point and the intermediate variable r1, as shown in the following formula set:

[0037]

[0038] The first formula from top to bottom in the formula group is to solve the equation of the first piezoelectric sensor in the x-axis direction. After eliminating the quadratic term, the distance r1 is derived algebraically. The second formula from top to bottom is used to solve the x-axis coordinate of the target point. The third formula from top to bottom is used to solve the y-axis coordinate of the target point. The fourth formula from top to bottom is used to solve the burial depth z of the target point.

[0039] The host computer converts the time difference into a distance difference based on the sound wave propagation time difference, further optimizing and correcting the positioning of the target point's spatial coordinates, thus improving the calculation accuracy. The formula is as follows:

[0040]

[0041] Where (x1, y1, z1) and (x2, y2, z2) are the coordinates of any two piezoelectric sensors in the piezoelectric integrated circuit sensor, v is the propagation speed of the sound wave in the soil medium, and Δt12 is the time difference between the sound waves received by any two piezoelectric sensors. Here, any two piezoelectric sensors refer to any two piezoelectric sensors selected from the first, second, third, and fourth piezoelectric sensors.

[0042] Furthermore, the host computer establishes a motion model and predicts the state of the motion model. The prediction error is updated according to the motion model and noise, as shown in the following formula:

[0043]

[0044] The x k|k-1 Let Fk be the predicted state value at time k, Fk be the state transition matrix describing how the state changes from k-1 to k, Bk be the control input matrix, and if there is external control, uk be the control input at time k. k|k-1 Let be the prediction error covariance matrix at time k, used to describe the uncertainty of state prediction; and let Qk be the process noise covariance matrix, used to describe the disturbances in state transition.

[0045] The host computer combines the second digital signal from the second microcontroller to correct the predicted value and optimize the prediction accuracy, as shown in the following formula:

[0046]

[0047] Where Kk is the Kalman gain, which weighs the predicted and observed values; the lower the noise, the higher the weight. Hk is the observation matrix, which maps the state to the observation space. Rk is the observation noise covariance matrix, used to describe the uncertainty of sensor measurements. zk is the observation value at time k. The state estimate at time k is the optimal solution corrected by the host computer. The corrected prediction can be used to calculate the gain, balance the prediction with the actual observation, use the observation residual to correct the state, update the error covariance, recursively filter multiple sets of positioning data to suppress noise, and output the optimal solution, which is the positioning depth of the plane where the non-metallic pipe is located.

[0048] Furthermore, the host computer packages all marked interference points and transmission points into a training set. The host computer establishes an ARIMA time series model, and the parameters of the time series model are optimized using the AIC criterion. The packaged training set is input into the time series model for training. After training, the intensity value of the interference signal within the future window is predicted. The time series model uses the training set to predict the trend and regularity of the interference signal, such as the interference signal gradually increasing, decreasing, or intermittently increasing or decreasing. By predicting the changing trend of the interference signal within the future window, the system can select the time when the interference signal is weakest to send the detection sound wave, reducing the interference of external environmental noise on the detection sound wave. The intensity value of the interference signal within the future window is the interference pattern.

[0049] The host computer takes the point with the lowest intensity value within the interference pattern as the propagation point, and the time axis of the propagation point forward Dis / 2v as the transmission point, where Dis is the distance between the transmitting end and the receiving end, and v is the propagation speed of the sound wave in the soil medium. The host computer sends a detection command to the first microcontroller according to the transmission point, and the first microcontroller sends the sound wave according to the time point of the transmission point.

[0050] Furthermore, the host computer continuously records the magnitude of the change in the adjustment threshold Ytz within each fixed period. If the magnitude of the change in the adjustment threshold Ytz increases by more than 10% month-on-month, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are reduced by 0.1. If the magnitude of the change in the adjustment threshold Ytz decreases by 10% month-on-month, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are increased by 0.05. If the magnitude of the increase or decrease in the adjustment threshold is within 10% month-on-month, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 remain unchanged. By dynamically changing the values ​​of the first adjustment coefficient tj1 and the second adjustment coefficient tj2, the sensitivity of the first interference threshold yz1 and the second interference threshold yz2 can be automatically optimized to adapt to different detection environments.

[0051] The present invention has the following beneficial effects:

[0052] 1. By setting dynamic first and second interference thresholds, different detection methods can be automatically selected according to the on-site detection environment, enhancing the versatility of the detection equipment. By executing the interference analysis process, the interference pattern of the interference signal is predicted, and detection sound waves are emitted during the gaps where the interference signal is weak, thereby reducing the impact of the interference signal on the detection results.

[0053] 2. By performing an interference resistance process, the waveform characteristics of the interference signal are analyzed. Based on the waveform characteristics of the interference signal, an anti-phase wave is generated, and then a resistance wave is emitted to cancel the influence of the interference signal. This enhances the stability of the detection wave, improves the accuracy of the detection data, and increases the success rate of the detection mission. The resistance wave and the detection wave are transmitted in a frequency division manner, which can reduce the secondary interference of the resistance wave on the detection wave.

[0054] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a system block diagram of the non-metallic pipe burial depth detection equipment based on active acoustic waves according to the present invention;

[0057] Figure 2 This is a schematic diagram of a quaternary sensor array arranged in the piezoelectric integrated circuit sensor of the present invention;

[0058] The attached diagram lists the components represented by each number as follows:

[0059] In the diagram: 1-First piezoelectric sensor, 2-Second piezoelectric sensor, 3-Third piezoelectric sensor, 4-Fourth piezoelectric sensor, 5-Receiver, 6-Transmitter, 7-Speaker. Detailed Implementation

[0060] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Please see Figure 1-2 This invention provides a technical solution: a non-metallic pipeline burial depth detection equipment based on active acoustic waves, such as... Figure 1As shown, the system includes a host computer, a first communication module (ESP8266), a speaker 7, a piezoelectric integrated circuit sensor, a transmitter 6, and a receiver 5. The transmitter 6 includes a data acquisition unit, a first microcontroller (STM32F103ZET6), and an audio amplifier (TPA3116D2). The receiver 5 includes a second communication module (ESP8266), a second microcontroller (STM32F103ZEGT6), and a digital-to-analog converter (ADS127L01). The host computer's port establishes bidirectional communication with the port of the first communication module. The output of the acquisition unit is connected to the input of the first communication module. The outputs of both the first communication module and the acquisition unit are connected to the input of the first microcontroller. The output of the first microcontroller is connected to the input of the audio amplifier. The output of the audio amplifier is connected to the input of the speaker 7. The output of the piezoelectric integrated circuit sensor is connected to the input of the digital-to-analog converter. The output of the digital-to-analog converter is connected to the input of the second microcontroller. The output of the second microcontroller is connected to the input of the second communication module. The output of the second communication module establishes communication with the input of the first communication module via wireless communication.

[0062] The acquisition unit obtains the vibration information of the ground where the transmitter 6 is located, marks it as an interference signal, and transmits it to the first microcontroller and the first communication module respectively. The first communication module sends the interference signal back to the host computer. The host computer sends a detection command to the first microcontroller through the first communication module. The first microcontroller sends a first digital signal to the audio amplifier. The audio amplifier amplifies the first digital signal to obtain a first analog signal. The audio amplifier sends the first analog signal to the speaker 7.

[0063] The loudspeaker 7 converts the first analog signal into a sound wave and emits the sound wave into the non-metallic pipe. The sound wave propagates along the inner axis of the non-metallic pipe through the gas medium inside the pipe. The sound wave passes through the soil medium and propagates three-dimensionally to the ground through the vibration of the pipe wall. The piezoelectric integrated circuit sensor acquires the sound wave that has propagated to the ground.

[0064] The piezoelectric integrated circuit sensor converts the acquired sound wave into a second analog signal and transmits it to a digital-to-analog converter. The digital-to-analog converter converts the second analog signal into a second digital signal and transmits it to a second microcontroller. The second microcontroller transmits the second digital signal to a first communication module through a second communication module. The first communication module forwards the second digital signal to a host computer. The host computer executes a signal calculation program based on the first and second digital signals to obtain the positioning depth of the plane where the non-metallic pipe is located.

[0065] Before the speaker 7 sends a detection sound wave into the non-metallic pipe, the host computer adjusts the detection command of the first microcontroller according to the interference signal obtained by the acquisition unit.

[0066] The host computer sets a first interference threshold and a second interference threshold. When the interference signal is lower than the first interference threshold, it means that there are few interference factors in the detection environment. The host computer executes the normal detection process. The second microcontroller uses a traversal algorithm to solve and filter valid data. When the interference signal is greater than the first interference threshold and less than the second interference threshold, it means that there are generally few interference factors in the detection environment. The host computer executes the interference analysis process to obtain the interference pattern of the interference signal. It predicts that the gap loudspeaker 7 with weaker interference signal will intermittently emit detection sound waves to avoid the influence of interference signal on detection sound waves. When the interference signal is greater than the second interference threshold, it means that there are many interference factors in the detection environment. At this time, it is necessary to execute the interference resistance process to obtain the waveform characteristics of the interference signal. Based on the waveform characteristics of the interference signal, a resistance sound wave is generated. The resistance sound wave and the normal detection sound wave are frequency-divided and transmitted. Frequency-divided transmission means that different frequencies are used for alternating transmission. The resistance sound wave uses phase cancellation to reduce the influence of interference signal on detection sound waves, thereby improving the reliability of detection data.

[0067] When the piezoelectric integrated circuit sensor collects and detects the sound wave, and the second microcontroller transmits the converted second digital signal back to the host computer through the second communication module, the host computer then executes the signal calculation program to obtain the positioning depth of the plane where the non-metallic pipe is located. At this point, the detection process, interference analysis process, or interference resistance process generally stops.

[0068] The first interference threshold and the second interference threshold are set as follows:

[0069] The host computer continuously acquires and normalizes interference signals from the acquisition unit. The host computer continuously acquires interference signals at a frequency of 50Hz. The maximum value in the interference signal is marked as 1. The remaining interference signals are converted proportionally according to the maximum value. The host computer calculates the average value of all interference signals and extracts the value of the interference signal that appears most frequently and marks it as a constant value. The average value and the constant value are used to represent the feature value of the interference signal. Based on the feature value, it is convenient to set the first interference threshold and the second interference threshold.

[0070] The absolute value of the difference between the average value and the constant value of the interference signal calculated by the host computer is marked as the adjustment threshold Ytz. The adjustment threshold is calculated from the average value and the constant value of the interference signal, reflecting the fluctuation degree of the interference signal. It can intuitively reflect the signal interference situation of the current detection environment. The adjustment threshold is used as the smallest adjustment unit for easy reference. It is also easy to adjust the first interference threshold yz1 and the second interference threshold yz2. One-third of the maximum power of the detection sound wave emitted by the speaker 7 is marked as the initial noise floor Dcs. The initial noise floor Dcs is set to avoid the initial value of the interference signal obtained by the acquisition unit being too small, which would affect the reasonable range of the first interference threshold and the second interference threshold. The power range of the detection sound wave emitted by the speaker 7 is determined by the host computer.

[0071] The host computer uses the formula group The first interference threshold yz1 and the second interference threshold yz2 are calculated, where tj1 is the first adjustment coefficient and tj2 is the second adjustment coefficient.

[0072] In general, during the detection process, the host computer sends a detection command to the first microcontroller through the first communication module. The first microcontroller controls the speaker 7 to emit detection sound waves. After receiving the second digital signal, the host computer executes the signal calculation program to perform a traversal algorithm for calculation. The calculation process is as follows:

[0073] like Figure 2 As shown, the piezoelectric integrated circuit sensor includes a first piezoelectric sensor 1, a second piezoelectric sensor 2, a third piezoelectric sensor 3, and a fourth piezoelectric sensor 4. The first piezoelectric sensor 1, the second piezoelectric sensor 2, the third piezoelectric sensor 3, and the fourth piezoelectric sensor 4 constitute... Figure 2 The host computer uses a four-element sensor array to construct spatial constraints and establish a spherical intersection model for detecting sound waves inside a non-metallic pipe. It then performs a preliminary calculation of the positioning depth in the plane containing the non-metallic pipe, using the following formulas:

[0074]

[0075] Where x, y, and z are the spatial coordinates of the target point, specifically the spatial coordinates of the sound wave detected by the piezoelectric integrated circuit sensor. Figure 2 The location of point L is defined by the Cartesian coordinate system formed by x and y, z is the burial depth of the non-metallic pipe, r is the distance from the piezoelectric integrated circuit sensor to the target point, M is the spacing between the first piezoelectric sensor 1, the second piezoelectric sensor 2, the third piezoelectric sensor 3, and the fourth piezoelectric sensor 4, d12 is the distance difference from the target point to the first piezoelectric sensor 1 and the second piezoelectric sensor 2, d13 is the distance difference from the target point to the first piezoelectric sensor 1 and the third piezoelectric sensor 3, d14 is the distance difference from the target point to the first piezoelectric sensor 1 and the fourth piezoelectric sensor 4, and r1 is the distance from the first piezoelectric sensor 2 to the target point.

[0076] The host computer uses the elimination method to solve the spherical equations simultaneously, corrects the spatial coordinates of the target point, establishes a motion model and predicts the state of the motion model, and combines the second digital signal of the second microcontroller to correct the predicted value and output the positioning depth of the plane where the non-metallic pipe is located.

[0077] During the interference analysis process, the system predicts the weakest time window of the interference and controls the speaker 7 to intermittently emit detection sound waves to avoid interference covering the signal. The unprocessed interference signal is a continuous signal. The host computer splits the interference signal into short time frames, for example, each short time frame has 1024 sampling points, and adjacent short time frames overlap by 512 sampling points to achieve cross-overlap. This splits the continuous signal into short time segments, which facilitates the analysis of the time-varying characteristics of the interference. The host computer establishes a signal strength curve, with the horizontal axis representing time and the vertical axis representing the strength value of the interference signal. The host computer extracts the strength value of the interference signal in each short time frame and inputs it into the strength curve to obtain the strength point corresponding to each short time frame. The coordinates of the strength point are represented as (Xqd, Yqd), which means that the strength value of the interference signal at time point Xqd is Yqd.

[0078] The host computer uses a fitted curve to connect the intensity points of each short frame. The host computer uses a horizontal line segment to be tangent to each peak and trough of the fitted curve. The intersection of the tangent peaks is marked as the interference point, and the intersection of the tangent troughs is marked as the transmission point.

[0079] The host computer packages all marked interference points and transmission points into a training set. The host computer establishes an ARIMA time series model, inputs the training set into the time series model for training to obtain interference patterns, and determines the time point of sound wave transmission based on the interference patterns.

[0080] The subsequent execution of the signal calculation program by the host computer is the same as the general detection program, and will not be described in detail here, to obtain the positioning depth of the plane where the non-metallic pipe is located under the interference analysis process.

[0081] During the interference mitigation process, the host computer uses a Fast Fourier Transform to convert the time domain of the interference signal into the frequency domain, as shown in the following formula:

[0082]

[0083] Where q(n) is the time-domain interference signal, i.e., discrete sampling points; Q(m) is the frequency-domain amplitude spectrum, m is the frequency; N is the number of sampling points of the interference signal; e is the natural constant, which facilitates frequency domain analysis of the interference signal; j is the imaginary unit, which is generally used in signal processing in engineering fields to convert the discrete time-domain signal to the frequency domain for analysis and processing through this complex exponential operation, helping to extract features such as frequency, phase, and amplitude of the signal; and j satisfies the condition j 2 =-1;

[0084] The host computer performs phase analysis on the interference signal converted to the frequency domain, and takes the complex argument of the result of the fast Fourier transform to obtain the phase spectrum:

[0085]

[0086] in, Let Re be the phase angle corresponding to frequency m, Re|Q(m)| be the real part in the frequency domain, and Im|Q(m)| be the imaginary part in the frequency domain. By calculating the phase spectrum above, the phase relationship between each frequency of the interference signal can be determined, providing a reference for generating anti-phase waves.

[0087] The host computer performs amplitude estimation on the phase spectrum calculation results. It also calculates the absolute value of the frequency domain amplitude spectrum to obtain the amplitude at each frequency, using the following formula:

[0088] A(m)=|Q(m)|

[0089] Where A(m) is the amplitude corresponding to frequency m. By calculating the amplitude A, the interference intensity of the interference signal can be quantified, thereby determining the amplitude of the resisting sound wave.

[0090] The host computer establishes a feature model and converts the phase spectrum. In the input feature model with amplitude A(m), the waveform characteristics of the interference signal are obtained. The host computer generates an inverted wave based on the waveform characteristics. The host computer sends the inverted wave along with the detection command to the first microcontroller. The first microcontroller sends the resisting sound wave according to the inverted wave. The resisting sound wave and the detection sound wave are sent alternately at different frequencies.

[0091] The subsequent execution of the signal calculation program by the host computer is the same as the general detection program, and will not be described in detail here, to obtain the positioning depth of the plane where the non-metallic pipe is located under the interference resistance process.

[0092] The host computer uses the elimination method to solve the simultaneous equations of the sphere, deriving the spatial coordinates (x, y, z) of the target point and the intermediate variable r1. The formula set is as follows:

[0093]

[0094] The first formula from top to bottom in the formula group is to solve the equation of the first piezoelectric sensor 1 in the x-axis direction. After eliminating the quadratic term, the distance r1 is derived algebraically. The second formula from top to bottom is used to solve the x-axis coordinate of the target point. The third formula from top to bottom is used to solve the y-axis coordinate of the target point. The fourth formula from top to bottom is used to solve the burial depth z of the target point, where z is a real number and takes a positive value.

[0095] The host computer converts the time difference into a distance difference based on the sound wave propagation time difference, further optimizing and correcting the positioning of the target point's spatial coordinates, thus improving the solution accuracy. The formula is as follows:

[0096]

[0097] Where (x1, y1, z1) and (x2, y2, z2) are the coordinates of any two piezoelectric sensors in the piezoelectric integrated circuit sensor, v is the propagation speed of the sound wave in the soil medium, and Δt12 is the time difference between the sound waves received by any two piezoelectric sensors. Here, any two piezoelectric sensors refer to any two piezoelectric sensors selected from the first piezoelectric sensor 1, the second piezoelectric sensor 2, the third piezoelectric sensor 3, and the fourth piezoelectric sensor 4.

[0098] The host computer establishes a motion model and predicts the state of the motion model. The prediction error is updated according to the motion model and noise, as shown in the following formula:

[0099]

[0100] x k|k-1 Fk represents the predicted state value at time k, such as position, velocity, and vector form. Fk is the state transition matrix, which describes how the state changes from time k-1 to time k, for example, in a uniform velocity model. Bk is the control input matrix. If there is external control, such as acceleration, uk is the control input at time k, such as the acceleration vector. P k|k-1 Let Qk be the prediction error covariance matrix at time k, used to describe the uncertainty of state prediction, and let Qk be the process noise covariance matrix, used to describe the disturbances in state transition, such as environmental noise.

[0101] The host computer, in conjunction with the second digital signal from the second microcontroller, corrects the predicted value and optimizes the prediction accuracy. The formula is as follows:

[0102]

[0103] Where Kk is the Kalman gain, which weighs the predicted and observed values, with lower noise levels resulting in higher weights; Hk is the observation matrix, mapping the state to the observation space, such as in the measurement model of a piezoelectric integrated circuit sensor; Rk is the observation noise covariance matrix, used to describe the uncertainty of sensor measurements, such as noise variance; and zk is the observed value at time k, such as the second analog signal converted by the piezoelectric integrated circuit sensor. The state estimate at time k is the optimal solution corrected by the host computer. The corrected prediction can be used to calculate the gain, balance the prediction with the actual observation, use the observation residual to correct the state, and update the error covariance. Multiple sets of positioning data are recursively filtered to suppress noise, such as the convergence value after 10 sets of data iterations. The optimal solution is output, which is the positioning depth of the plane where the non-metallic pipe is located.

[0104] The host computer packages all marked interference points and transmission points into a training set. The host computer establishes an ARIMA time series model, and the parameters of the time series model are optimized using the AIC criterion. The packaged training set is input into the time series model for training. After training, the strength of the interference signal within a future window of 10 seconds is predicted. The time series model uses the training set to predict the trend and regularity of the interference signal, such as the interference signal gradually increasing, decreasing, or intermittently increasing or decreasing. By predicting the changing trend of the interference signal within the future window, the system can select the time when the interference signal is weakest to send the detection sound wave, reducing the interference of external environmental noise on the detection sound wave. The predetermined future window is 10 seconds, which is enough time for the detection equipment to complete a complete detection task. The strength of the interference signal within the future window is the interference pattern.

[0105] The host computer takes the point with the lowest intensity value within the interference pattern as the propagation point, and the time axis of the propagation point forward Dis / 2v as the transmission point, where Dis is the distance between the transmitting end 6 and the receiving end 5, and v is the propagation speed of the sound wave in the soil medium. The host computer sends a detection command to the first microcontroller according to the transmission point. The first microcontroller sends the detection sound wave according to the time point of the transmission point. After the loudspeaker emits the detection sound wave at the transmission point, the detection sound wave propagates inside the non-metallic pipe for a certain period of time before being acquired by the piezoelectric circuit integrated sensor. There is a certain time difference between the transmission, propagation and acquisition of the detection sound wave. Therefore, when the loudspeaker emits the detection sound wave, it needs to be based on the propagation point when the interference is at its lowest in the non-metallic pipe. Based on this, the detection sound wave needs to be sent a certain amount of time in advance, which is Dis / 2v, so that the detection sound wave is exactly at the propagation point when the interference is at its lowest when it propagates in the non-metallic pipe.

[0106] The host computer continuously records the change in the value of the adjustment threshold Ytz within each fixed 10-minute period. If the change in the value of the adjustment threshold Ytz increases by more than 10% compared to the previous period, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are reduced by 0.1. If the change in the value of the adjustment threshold Ytz decreases by 10% compared to the previous period, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are increased by 0.05. If the change in the adjustment threshold is within 10% (inclusive), the first adjustment coefficient tj1 and the second adjustment coefficient tj2 remain unchanged. By dynamically changing the values ​​of the first adjustment coefficient tj1 and the second adjustment coefficient tj2, the sensitivity of the first interference threshold yz1 and the second interference threshold yz2 can be automatically optimized to adapt to different detection environments.

[0107] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An active acoustic based non-metallic pipeline depth detection apparatus, characterized in that: The utility model relates to a kind of nonmetallic pipeline detection systems, including host computer, first communication module, loudspeaker (7), piezoelectric integrated circuit sensor, transmitting end (6) and receiving end (5), the transmitting end (6) includes acquisition unit, first single-chip microcontroller and audio amplifier, the receiving end (5) includes second communication module, second single-chip microcontroller and digital-analog converter, the port of host computer and the port of first communication module establish two-way communication, the output of acquisition unit is connected with the input of first communication module, the output of first communication module and acquisition unit is connected with the input of first single-chip microcontroller, the output of first single-chip microcontroller is connected with the input of audio amplifier, the output of audio amplifier is connected with the input of loudspeaker (7), the output of piezoelectric integrated circuit sensor is connected with the input of digital-analog converter, the output of digital-analog converter is connected with the input of second single-chip microcontroller, the output of second single-chip microcontroller is connected with the input of second communication module, the output of second communication module is communicated with the input of first communication module by wireless communication; The acquisition unit obtains the vibration information of the ground where transmitting end (6) is located, and the vibration information is marked as interference signal and transmitted to first single-chip microcontroller and first communication module respectively, the first communication module returns the interference signal to host computer, the host computer sends detection instruction to first single-chip microcontroller through first communication module, the first single-chip microcontroller sends first digital signal to audio amplifier, the audio amplifier amplifies the first digital signal to obtain first analog signal, and the audio amplifier sends the first analog signal to loudspeaker (7); The loudspeaker (7) emits detection sound wave in the nonmetallic pipeline, the detection sound wave propagates along the axial direction of the nonmetallic pipeline through the gas medium in the nonmetallic pipeline, and the detection sound wave propagates to the ground through the soil medium and the pipe wall vibration, and the piezoelectric integrated circuit sensor obtains the detection sound wave propagating to the ground; The piezoelectric integrated circuit sensor converts the obtained detection sound wave into second analog signal and transmits the second analog signal to digital-analog converter, the digital-analog converter converts the second analog signal into second digital signal and transmits the second digital signal to second single-chip microcontroller, the second single-chip microcontroller transmits the second digital signal to first communication module through second communication module, the first communication module forwards the second digital signal to host computer, and the positioning depth of the plane where the nonmetallic pipeline is located is obtained by executing signal solving program according to the first digital signal and the second digital signal; Before the loudspeaker (7) emits detection sound wave into the nonmetallic pipeline, the host computer adjusts the detection instruction of the first single-chip microcontroller according to the interference signal obtained by the acquisition unit. The first interference threshold and the second interference threshold are set, when the interference signal is lower than the first interference threshold, a general detection process is performed, the second single chip uses a traversal algorithm to solve and screen effective data, when the interference signal is greater than the first interference threshold and less than the second interference threshold, an interference analysis process is performed to obtain the interference law of the interference signal, the loudspeaker (7) intermittently emits a detection sound wave in a gap where the interference signal is weak, when the interference signal is greater than the second interference threshold, an interference resistance process needs to be performed to obtain the waveform characteristics of the interference signal, and a resistance sound wave is generated according to the waveform characteristics of the interference signal; the resistance sound wave and the detection sound wave are frequency-divided and emitted; When the piezoelectric integrated circuit sensor collects the detection sound wave and the second digital signal converted by the second single chip is transmitted back to the upper computer through the second communication module, a signal solving program is executed to obtain the positioning depth of the plane where the non-metal pipeline is located, and the general detection process, the interference analysis process or the interference resistance process stops.

2. The active sound wave based non-metallic pipeline depth detection apparatus according to claim 1, wherein, The first interference threshold and the second interference threshold are set as follows: The upper computer continuously obtains the interference signal from the acquisition unit and normalizes, calculates the average value of all interference signals, and extracts the most frequently occurring value of the interference signal as a constant value; The absolute value of the difference between the average value of the interference signal and the constant value is calculated and marked as an adjustment threshold Ytz, and 1 / 3 of the maximum power of the detection sound wave emitted by the loudspeaker (7) is marked as an initial bottom noise Dcs; According to the formula set The first interference threshold yz1 and the second interference threshold yz2 are calculated, where tj1 is a first adjustment coefficient and tj2 is a second adjustment coefficient.

3. The active acoustic based non-metallic pipeline depth probe of claim 1, wherein, When the general detection process is performed, the upper computer sends a detection instruction to the first single chip through the first communication module, the first single chip controls the loudspeaker (7) to emit a detection sound wave, and after the upper computer receives the second digital signal, a signal solving program is executed to perform a traversal algorithm for solving, and the solving process is as follows: The piezoelectric integrated circuit sensor includes a first piezoelectric sensor (1), a second piezoelectric sensor (2), a third piezoelectric sensor (3) and a fourth piezoelectric sensor (4), the first piezoelectric sensor (1), the second piezoelectric sensor (2), the third piezoelectric sensor (3) and the fourth piezoelectric sensor (4) form a four-element sensor array, a spatial constraint is constructed through the four-element sensor array, a spherical intersection model of the detection sound wave in the non-metal pipeline is established, and the formula group is as follows: ； Where x, y, and z are the spatial coordinates of the target point, the target point is the spatial coordinate of the sound wave detected by the piezoelectric integrated circuit sensor, r is the distance from the piezoelectric integrated circuit sensor to the target point, M is the spacing between the first piezoelectric sensor (1), the second piezoelectric sensor (2), the third piezoelectric sensor (3), and the fourth piezoelectric sensor (4), and d is the distance between the target point and the piezoelectric sensor (4). 12 Let d be the distance difference from the target point to the first piezoelectric sensor (1) and the second piezoelectric sensor (2). 13 d is the distance difference from the target point to the first piezoelectric sensor (1) and the third piezoelectric sensor (3). 14 r1 is the distance difference between the target point and the first piezoelectric sensor (1) and the fourth piezoelectric sensor (4), and r1 is the distance from the first piezoelectric sensor (1) to the target point. By using the elimination method to solve the spherical equation, the positioning of the spatial coordinates of the target point is corrected, a motion model is established and the state of the motion model is predicted, the predicted value is corrected in combination with the second digital signal of the second single chip, and the positioning depth of the plane where the non-metal pipeline is located is output.

4. The active acoustic based non-metallic pipeline depth finder apparatus of claim 1, wherein, When the interference analysis process is performed, the unprocessed interference signal is a continuous signal, the upper computer splits the interference signal into short-time frames, establishes a signal intensity curve, the horizontal axis is time, the vertical axis is the intensity value of the interference signal, the intensity value of the interference signal of each short-time frame is extracted and input into the intensity curve to obtain the intensity point corresponding to each short-time frame; The intensity points of each short-time frame are connected using a fitting curve, a horizontal line segment is tangent to each peak and valley of the fitting curve, the intersection point of the tangent peaks is marked as an interference point, and the intersection point of the tangent valleys is marked as an emission point. All the marked interference points and emission points are packaged into a training set, a time series model is established, the training set is input into the time series model for training to obtain an interference law, and a time point of sending a detection sound wave is determined based on the interference law; The subsequent signal calculation program is executed in the same way as the general detection program, and the positioning depth of the non-metal pipeline in the plane is obtained.

5. The active acoustic based non-metallic pipeline depth probe of claim 1, wherein, When the interference resistance process is executed, the host computer converts the time domain of the interference signal into the frequency domain using fast Fourier transform, and the formula is as follows: ； Wherein, q(n) is a time domain interference signal, i.e. a discrete sampling point, Q(m) is a frequency domain amplitude spectrum, m is a frequency, N is a sampling point number of the interference signal, e is a natural constant, j is an imaginary unit, and j satisfies the condition ; The phase spectrum is calculated by performing phase analysis on the interference signal converted into the frequency domain, and the amplitude angle of the complex number is obtained. ； wherein, is the phase angle corresponding to the frequency m, is the real part of the frequency domain, is the imaginary part of the frequency domain; The amplitude of each frequency is obtained by calculating the absolute value of the frequency domain amplitude spectrum, and the formula is as follows: ； Where A(m) is the amplitude corresponding to the frequency m. A characteristic model is established, and a phase spectrum and an amplitude The waveform characteristics of the interference signal are obtained by inputting the characteristic model, and an inverse wave is generated based on the waveform characteristics. The inverse wave is sent to the first single-chip microcomputer together with the detection instruction. The first single-chip microcomputer sends a resistance sound wave according to the inverse wave. The resistance sound wave and the detection sound wave are sent alternately at different frequencies. The subsequent signal calculation program is executed in the same way as the general detection program, and the positioning depth of the non-metal pipeline in the plane is obtained.

6. The active acoustic based non-metallic pipeline depth probe of claim 3, wherein, The host computer solves the spherical equation by the elimination method, and derives the spatial coordinates (x, y, z) of the target point and the intermediate variable r1, and the formula group is as follows: ； The first formula from top to bottom in the formula group is the equation of the first piezoelectric sensor (1) in the x-axis direction, and the distance r1 is algebraically derived after eliminating the quadratic term, the second formula is used to solve the coordinates of the target point in the x-axis direction, the third formula is used to solve the coordinates of the target point in the y-axis direction, and the fourth formula is used to solve the burial depth z of the target point; The time difference is converted into a distance difference based on the sound wave propagation time difference, and the positioning of the spatial coordinates of the target point is corrected, and the formula is as follows: ； where (x1, y1, z1) and (x2, y2, z2) are the coordinates of any two piezoelectric sensors in the piezoelectric integrated circuit sensor, v is the propagation speed of the detection acoustic wave in the soil medium, and Δt 12 is the time difference between the detection acoustic wave received by any two piezoelectric sensors.

7. The active acoustic based non-metallic pipeline depth finder apparatus of claim 3, wherein, The host computer establishes a motion model and predicts the state of the motion model, and the prediction error is updated with the motion model and noise, and the formula is as follows: ； The is the state prediction value at time k, F k is the state transition matrix, u k is the control input at time k, is the prediction error covariance matrix at time k, Q k is the process noise covariance matrix; The second digital signal of the second single-chip microcomputer is combined to correct the predicted value, and the formula is as follows: ； where K k is the Kalman gain, H k is the observation matrix, R k is the observation noise covariance matrix, z k is the observation value at time k, is the state estimation value at time k, and the output optimal solution is the positioning depth of the non-metallic pipeline in the plane.

8. The active acoustic based non-metallic pipeline depth finder apparatus of claim 4, wherein, The host computer packages all the marked interference points and emission points into a training set, establishes a time series model, optimizes the parameters of the time series model by AIC criterion, inputs the packaged training set into the time series model for training, and predicts the intensity value of the interference signal in the future window after training, which is the interference law; The lowest intensity value in the interference law is taken as the propagation point, the emission point is Dis / 2v ahead of the time axis of the propagation point, Dis is the distance between the emission end (6) and the receiving end (5), v is the propagation speed of the detection sound wave in the soil medium, and the detection instruction is sent to the first single-chip microcomputer according to the time point of the emission point, and the first single-chip microcomputer sends the detection sound wave according to the time point of the emission point.

9. The active acoustic based non-metallic pipeline depth finder apparatus of claim 2, wherein, The host computer records the numerical change amplitude of the adjustment threshold Ytz in each fixed period, if the numerical change amplitude of the adjustment threshold Ytz increases by more than 10% compared with the previous period, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are reduced by 0.1, if the numerical change amplitude of the adjustment threshold Ytz decreases by 10% compared with the previous period, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are increased by 0.05, and if the numerical change amplitude of the adjustment threshold is less than 10% compared with the previous period, the first adjustment coefficient tj1 and the second adjustment coefficient tj2 are not changed.

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