JP2024511690A - Active detection method and system for sealing of doors and leakage point location - Google Patents

Abstract

The present invention discloses a method and system for active detection of leak point locations. The active detection method includes step S1 of acquiring a set threshold value of the reference sound pressure, and transmitting a pulsed ultrasonic signal by a pulsed ultrasonic generator placed on one side of the protective door, and transmitting a pulsed ultrasonic signal by an array detector at various detection distances. step S2 of collecting raw signals of four channels, processing them to extract sound pressure feature values of the four channels, and collecting images and test distance; and the extracted sound pressure feature values of the four channels and the reference. Step S3 of setting the threshold for each leakage class based on the set threshold of sound pressure, and detecting the sound pressure value by the array detector on the other side of the protective door, and when the sound pressure value to be tested exceeds the first class leakage threshold. , perform envelope cross-correlation operation based on adaptive filtering on the raw signals of the four channels to obtain the three delay differences between the three channels and the remaining one channel, and calculate the ratio of the test distance to the sound pressure amplitude. and a step S4 of calculating the three-dimensional spatial coordinates of the leak point by combining and fusing these with the sound pressure values to be tested of the four channels.

Description

(Cross reference to related applications)
This application claims the benefit of Chinese Patent Application No. 202210181445.9 filed on February 25, 2022, the contents of which are incorporated herein by reference.

The present invention relates to the technical field of leak detection, and specifically to a method and system for active detection of leak point locations.

Civil defense construction is a special underground building with strict protection requirements, which must not only meet the demands of normal economic construction, urban construction and people's life, but also play an important role in wartime air defense and disaster prevention. It necessarily has a dual function for peacetime and wartime, and if protection and sealing work is not done adequately, it will cause huge losses to the national economy and even threaten the safety of people's lives. Detection of hermeticity in civil defense construction facilities is very important as it poses a threat to civil defense construction facilities.

Currently, concrete defect detection using ultrasound mainly determines the defect status of concrete by measuring relative changes in acoustic parameters such as velocity, amplitude, and main frequency of ultrasonic pulse waves propagating in concrete. do. However, in order to detect the tightness of a concrete protective door, it is necessary to pay attention to the gap in the door and the tightness of the bonded area of the rubber strip, which is different from the principle of defect detection using traditional ultrasonic methods. different. In addition, the structure of the civil defense basement is sealed, the structure of the concrete protective door is enormous, the amount of construction work is enormous, and ultrasonic detection technology is required to quickly and accurately detect the location of the leak point. It is being

It is acknowledged that the information disclosed in the background section is solely for the purpose of enhancing the understanding of the general background of the invention and that the information constitutes prior art already known to those skilled in the art. shall not be considered or in any way implied.

The present invention provides a method and system for active detection of leak point locations in order to solve the problems pointed out in the above-mentioned background art.

In order to achieve the above object, the present invention
A step S1 in which a background sound pressure value of the current environment is detected by sound pressure receivers placed at four corners of the protective door, and the average value of the four background sound pressure values is set as a reference sound pressure threshold;
A pulsed ultrasonic generator disposed on one side of the protective door transmits a pulsed ultrasonic signal at predetermined time intervals, and raw signals of four channels are collected by an array detector at various detection distances, respectively. step S2 of converting raw signals of one channel into four channel voltage signals, extracting sound pressure feature values of four channels based on the four channel voltage signals, and collecting an image and a test distance regarding the protective door; ,
Step S3 of setting a threshold value for each leakage class based on the extracted sound pressure characteristic values of the four channels and the set threshold value of the reference sound pressure;
On the other side of the protective door, an array detector is used to detect the sound pressure value by moving it along the guideline of the image, to obtain the sound pressure values of the four channels, and to detect the sound pressure values of the four channels. The average value of the pressure values is compared with the threshold value of each leakage class, and if the average value of the sound pressure values to be tested exceeds the first class leakage threshold, it indicates that a leak exists in the current environment, and the four An envelope cross-correlation operation based on adaptive filtering is performed on the raw signals of the channels to obtain three delay differences between three of the four channels and the remaining one channel, and the test distance and the An active detection method for a leak point position is provided, which includes a step S4 of calculating three-dimensional spatial coordinates of a leak point by combining and fusing sound pressure values of four channels.

In one preferred embodiment,
If the sound pressure value to be tested is below the first class leakage threshold and the amount of leakage in the current environment is small, the analog microphone linear array is moved in space so that the sound pressure value to be tested is equal to or less than the first class leakage threshold. Step S5 of repeating step S4 when the threshold value is exceeded;
The method further includes a step S6 of mapping the three-dimensional space coordinates and the image coordinates to visibly superimpose the points indicated by the colored contour lines on the video to visualize the leakage points.

In one preferred embodiment, in step S2, extracting the sound pressure feature values of the four channels includes:
The signal-conditioned four channel voltage signals are extracted step by step, and for each channel voltage signal, they are sorted according to the magnitude of the amplitude in the time domain, and the data segments whose amplitude is 80-90% of the maximum value are extracted. a waveform selection and smoothing filtering step S2.1 of selecting and forming valid data segments corresponding to each of said channel voltage signals (i.e. excluding other data points);
step S2.2 of increasing the data sampling points by performing three spline interpolation operations for each selected valid data segment;
The frequency distribution of the data is statisticized, each peak value of the valid data segment is taken as the voltage characteristic value U of the corresponding channel, and the conversion formula from voltage to sound pressure is calculated.
step S2.3 of obtaining the sound pressure feature value SPL of the corresponding channel using the method.

In one preferred embodiment, in step S3, setting a threshold value for each leakage class based on the extracted sound pressure feature values of the four channels and the set threshold value of the reference sound pressure includes:
Step S3.1 of calculating the average value of the sound pressure feature values of the four channels obtained in step S2 and obtaining an attenuation curve with the detection distance of the sound pressure feature value;
At each test distance, the difference between the sound pressure feature value and the reference sound pressure setting threshold obtained in step S1 was calculated, and 10%, 30%, and 50% of the difference were added to the reference sound pressure setting threshold. a first-class leakage threshold, a second-class leakage threshold, and a third-class leakage threshold, respectively, wherein the first-class leakage threshold indicates that leakage can be ignored, and the second-class leakage threshold indicates that leakage cannot be ignored, but immediately Step S3.2 represents that there is no need to repair the leak, and the third grade leakage threshold represents that the leakage cannot be ignored and must be repaired immediately.

In one preferred embodiment, in step S4, fusing these to calculate the three-dimensional spatial coordinates of the leak point includes:
Similar to forming valid data segments in step S2.1, extract valid data segments from the raw signals of the four channels obtained in step S2 and average the amplitude of two data segments for every 100 data points. step S4.1 of comparing the difference in values to find a data segment in which a pulse signal appears and taking 100 data points before and after the data segment;
A step of extracting an envelope for the selected data segment and performing a cross-correlation calculation on two channel envelopes, the cross-correlation calculation formula for the two channels being as follows:
and
Step S4.2, where x ₁ (n) and x ₂ (n) are the signal arrays of channel 1 and channel 2, respectively, and τ is the number of delay points,
Input the two channel envelopes into the adaptive filter, assign a weight vector to one of the channels, calculate the iteration error based on the adaptive filtering algorithm, and constantly update the weight coefficient until the iteration error is minimized. , at this time, the correlation between the two channels is maximum, and the number of delay points for the two channels is calculated using the formula in step S4.2, and three delay points for the three channels and the remaining one channel are obtained. step S4.3, performing feature transformation on the three delay points to obtain three arrival time differences, and then multiplying each of the three arrival time differences by the speed of sound to obtain three arrival distance differences; ,
step S4.4 of performing feature transformation on the test sound pressure values of the four channels to obtain three arrival distance ratios;
With the test distance as one component of the three-dimensional spatial coordinates of the leak point, a first simultaneous spherical coordinate equation is created for the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance differences. Then, based on the three arrival distance ratios, a second simultaneous spherical coordinate equation is created for the three-dimensional spatial coordinates with the center of the linear array as the origin, and the first simultaneous spherical coordinate equation and the second spherical coordinate are Step S4.5 of solving the three-dimensional spatial coordinates from the results of the simultaneous equations using a fusion algorithm.

In one preferred embodiment, in step S4.4.4, performing a feature transformation on the tested sound pressure values of the four channels to obtain three arrival distance ratios corresponding to the four channels comprises:
Using the attenuation curve obtained in step S3.1, first convert the test sound pressure values of the four channels into four corresponding distances, and then convert the three of the four distances. calculating a ratio between each of the three distances corresponding to a channel and another distance corresponding to the remaining one channel;

In one preferred embodiment, the mapping process in step S6 includes:
step S6.1 of dividing the video screen into 320*180 grids and making each pixel point correspond to each three-dimensional space coordinate;
With the center of the video screen as the origin, the origin is mapped to the center of the linear array, a reference target is moved, and an interval point number is the number of pixels corresponding to a unit distance in the abscissa axis direction or the ordinate axis direction in the video screen. step S6.2 of establishing a mapping relationship between and a test distance;
and step S6.3 of converting the three-dimensional space coordinates calculated in step S4.5 into pixel coordinate points according to the established mapping relationship, and superimposing and displaying the pixel coordinate points on the screen.

In one preferred embodiment, if it is detected that a leakage point exists in the space but is outside the display range of the video screen, moving to the left or right until the positioning point appears on the screen and performing step S4. further including.

In one preferred embodiment, the sampling frequency of the four analog microphone linear arrays is 100kHz, and the sound pressure receiver includes a power supply module and a wireless transmission module, and is attracted to the protective door by a magnet, and the current level collected by the wireless transmission module is The background sound pressure value of the environment is transmitted to the computer.

In one preferred embodiment, the step of setting the average value of the four background sound pressure values as the reference sound pressure setting threshold is performed when the waves of the four background sound pressure values are within a preset range. Ru.

The present invention further includes:
four sound pressure receivers arranged at four corners of the protective door to detect a background sound pressure value of the current environment and set an average value of the four background sound pressure values as a reference sound pressure setting threshold;
a pulsed ultrasonic generator that is placed on one side of the protective door and transmits a pulsed ultrasonic signal at predetermined time intervals;
Collect raw signals of four channels at various detection distances, convert the raw signals of the four channels into four channel voltage signals, and calculate the sound pressure feature values of the four channels based on the four channel voltage signals. an array detector that extracts and collects images and test distances regarding the guard door;
a setting device that sets a threshold value for each leakage class based on the extracted sound pressure characteristic values of the four channels and the set threshold value of the reference sound pressure,
The array detector further detects sound pressure values along the guidelines of the image on the other side of the protective door, obtains the sound pressure values of the four channels, and detects the sound pressure values of the four channels. If the average value of the tested sound pressure values exceeds the first class leakage threshold, it indicates that a leak exists in the current environment, and An envelope cross-correlation operation based on adaptive filtering is performed on the raw signal to obtain three delay differences between three of the four channels and the remaining one channel, and the test distance and the four An active detection system for a leak point position is provided, which is used to calculate three-dimensional spatial coordinates of a leak point in combination with a sound pressure value to be measured of a channel and by fusing these values.

In one preferred embodiment, the array detector includes a linear array of four analog microphones, a computer processing unit, a signal conditioning circuit board, a camera module, and a ranging module.

In one preferred embodiment, the sampling frequency of the four analog microphone linear arrays is 100kHz, the sound pressure receiver includes a power supply module and a wireless transmission module, and is attracted to the protective door by a magnet.

Compared with the prior art, the beneficial effects of the present invention are as follows.
1. The present invention utilizes active emission pulsed ultrasound signals, collects four channels of raw signals by four analog microphone linear arrays, and generates stable sound through waveform selection, smoothing filtering, and interpolation calculation optimization algorithms. extract the pressure feature values, calculate the delay difference of each channel through signal envelope cross-correlation, and calculate the three-dimensional spatial coordinates of the leak point position through data fusion iterations, thereby improving the accuracy and stability of positioning.
2. In the present invention, the occurrence of multiple leak points can be detected by visualizing the leak point position through mapping processing between three-dimensional spatial coordinates and pixel coordinates, and positioning by moving the linear array. Significantly improve detection efficiency.
3. In the present invention, the threshold value for each leakage grade is set based on the sound pressure feature values of the extracted four channels, so that the current detection environment can be adjusted to correspond to test scenarios with various environmental noises. You can set the threshold value for determining the leakage grade accordingly.
Other features and advantages of the invention are described in detail in the detailed description section below.

The drawings are provided to provide a further understanding of the embodiments of the invention, constitute a part of the specification, and together with the following detailed description, illustrate the embodiments of the invention. It is not intended to limit.

1 is a block diagram of a system of a preferred embodiment of the invention; FIG. 2 is a flowchart of a data fusion algorithm among positioning algorithms according to a preferred embodiment of the present invention. FIG. 3 is a diagram showing visualization of positioning results in the interface of the system of the present invention.

Hereinafter, the technical solution of the embodiments of the present invention will be clearly and completely described. All other embodiments that a person skilled in the art can obtain without any creative effort based on the embodiments of the present invention fall within the patentable scope of the present invention.
Example 1

As shown in FIGS. 1 and 2, the method for actively detecting the airtightness of doors and the location of leakage points according to a preferred embodiment of the present invention includes the following steps S1 to S6.

Step S1: The background sound pressure value of the current environment is detected by the sound pressure receivers placed at the four corners of the protective door, and the average value of the four background sound pressure values is set as the reference sound pressure setting threshold.
In step S1, the step of setting the average value of the four background sound pressure values as a reference sound pressure setting threshold is executed when the waves of the four background sound pressure values are within a preset range. For example, if the waves of the four background sound pressure values are ±5% or less, the average value of the four background sound pressure values is set as the reference sound pressure setting threshold.

Step S2: A pulsed ultrasound generator placed on one side of the protective door transmits a pulsed ultrasound signal at predetermined time intervals, and four channels of raw signals are transmitted by four analog microphone linear arrays at various detection distances. are respectively collected and converted into four-channel voltage signals on one side of the protective door, and the signal-conditioned four-channel voltage signals are transmitted to a computer processing unit, and the sound pressure characteristics of the four channels are transmitted by the computer processing unit. Extract the value and collect the video and test distance by camera module and ranging module.
Specifically, extracting the sound pressure feature values of the four channels includes the following steps S2.1 to S2.3.
Step S2.1: Waveform selection: Extract the four signal-conditioned channel voltage signals in stages, and sort them according to the amplitude size in the time domain for each channel voltage signal. Select a data segment that is ˜90% to form a valid data segment corresponding to each of the channel voltage signals (ie, exclude other data points).
Step S2.2: Balance filtering: perform three spline interpolation operations for each selected valid data segment to increase the data sampling points.
Step S2.3: Statistically calculate the frequency distribution of the data, set each peak value of the valid data segment as the voltage characteristic value U of the corresponding channel, and convert the voltage to sound pressure conversion formula.
is used to obtain the sound pressure feature value SPL of the corresponding channel.

Step S3: Set a threshold value for each leakage grade based on the extracted sound pressure feature values of the four channels and the set threshold value of the reference sound pressure.
Specifically, setting the threshold value for each leakage grade based on the extracted sound pressure feature values of the four channels and the set threshold value of the reference sound pressure involves the following steps S3.1 and S3.2. include.
Step S3.1: Calculate the average value of the sound pressure feature values of the four channels obtained in step S2, and obtain an attenuation curve with the detection distance of the sound pressure feature value.
Step S3.2: At each test distance, calculate the difference between the sound pressure feature value and the reference sound pressure setting threshold obtained in step S1, and set the reference sound pressure setting threshold to 10%, 30%, The sum of 50% is defined as the first-class leak threshold, second-class leak threshold, and third-class leak threshold, respectively, where the first-class leak threshold indicates that the leak can be ignored, and the second-class leak threshold indicates that the leak cannot be ignored, but it must be repaired immediately. The third grade leakage threshold indicates that the leakage cannot be ignored and must be repaired immediately.

Step S4: Use an array detector on the other side of the protective door to detect sound pressure values by moving it along the guidelines of the image, obtain test sound pressure values of the four channels, and obtain the sound pressure values of the four channels. Comparing the average value of the sound pressure values to be tested with the threshold value of each leakage class, if the average value of the sound pressure values to be tested exceeds the first class leakage threshold, indicating that a leak exists in the current environment, Performing an envelope cross-correlation operation based on adaptive filtering on the raw signals of the four channels to obtain three delay differences between three channels of the four channels and the remaining one channel, and performing the test. In combination with the distance and the tested sound pressure values of the four channels, these are fused to calculate the three-dimensional spatial coordinates of the leak point.
Specifically, calculating the three-dimensional spatial coordinates of the leak point by fusing these includes the following steps S4.1 to S4.5.
Step S4.1: Extract valid data segments from the raw signals of the four channels obtained in step S2, compare the difference in amplitude average values of the two data segments for every 100 data points, and determine the pulse signal. Find the data segment that appears and take the 100 data points before and after the data segment.
Step S4.2: Extract the envelope for the selected data segment, perform cross-correlation calculation on the two channel envelopes, and the cross-correlation calculation formula for the two channels is
and
Here, x _i (n) and x _j (n) are the signal arrays of channel i and channel j, respectively, i, j = 1, 2, 3, 4, and i and j are not equal, and τ is the delay It is a score.
In each embodiment, channel 1 is a reference channel (i.e., another of said four channels), and any channel of three of said four channels (e.g., channel 2) and said reference channel. The cross-correlation calculation formula between channels is
and
Here, x1(n) and x2(n) are the signal arrays of channel 1 and channel 2, respectively, and τ is the number of delay points.
Step S4.3: Input the two channel envelopes into the adaptive filter, assign a weight vector to one of the channels, calculate the iterative error until the iterative error is minimized based on the adaptive filtering algorithm, and calculate the weighting coefficient. is constantly updated, and at this time, the correlation between the two channels is maximized.
At this time, the delay points of the two channels are calculated using the formula in step S4.2, and when the three delay points of the three channels and the remaining one channel are obtained, the characteristics for the three delay points are determined. A transformation is performed to obtain three arrival time differences, and each of the three arrival time differences is then multiplied by the speed of sound to obtain three arrival distance differences.
Step S4.4: Perform feature transformation on the test sound pressure values of the four channels to obtain three arrival distance ratios.
Step S4.5: A first spherical surface about the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance differences, with the test distance as one component of the three-dimensional spatial coordinates of the leak point. Create simultaneous coordinate equations, create a second simultaneous spherical coordinate equation for the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance ratios, and create a second simultaneous equation for the spherical coordinates with the first simultaneous equation From the results of the second simultaneous spherical coordinate equations, three-dimensional spatial coordinates are solved using a fusion algorithm.
Furthermore, in step S4.4.4, feature transformation is performed on the tested sound pressure values of the channels to obtain three arrival distance ratios corresponding to the four channels. Using the attenuation curve, first convert the sound pressure values of the four channels into corresponding four distances, and then convert the three distances corresponding to the three channels among the four distances. calculating a ratio between each distance and another distance corresponding to the remaining one channel.

Step S5: If the sound pressure value to be tested is below the first class leakage threshold and the amount of leakage in the current environment is a small amount, move the analog microphone linear array in space so that the sound pressure value to be tested is When the first class leakage threshold is exceeded, step S4 is repeated.

Step S6: Mapping the three-dimensional space coordinates and the image coordinates to visually superimpose the points indicated by the colored contour lines on the video image, thereby visualizing the leakage points.
Specifically, the mapping process in step S6 includes the following steps S6.1 to S6.3.
Step S6.1: Divide the video screen into 320*180 grids, and make each pixel point correspond to each three-dimensional space coordinate.
Step S6.2: Taking the center of the video screen as the origin, map the origin to the center of the corresponding linear array, and move the reference target to correspond to a unit distance in the abscissa direction or the ordinate direction in the video screen. Establish a mapping relationship between the interval point number, which is the number of pixels to be measured, and the test distance.
Step S6.3: Convert the three-dimensional spatial coordinates calculated in step S4.5 into pixel coordinate points according to the established mapping relationship, and display the pixel coordinate points in a superimposed manner on the screen.
The method further includes the step of performing step S4 by moving to the left or right until the positioning point appears on the screen when it is detected that the leakage point exists in the space but is outside the display range of the video screen. Including further.
In addition, the sampling frequency of the four analog microphone linear arrays is 100kHz, and the sound pressure receiver includes a power supply module and a wireless transmission module, which is attracted to the protective door by a magnet, and the background sound of the current environment collected by the wireless transmission module. Transmit the pressure value to the computer.
Example 2

As shown in FIG. 1, the present invention further includes a linear array 301 (detection frequency is from audible to 80 kHz) consisting of four analog microphones, a pulse ultrasonic generator 302 whose frequency and amplitude can be adjusted, and a sound pressure An active detection system for detecting the sealing property of doors and the location of leakage points is provided, including a receiver 303, an array detector 304, a computer 305, a signal conditioning circuit board, a camera module, and a ranging module.

The sound pressure receivers 303 are placed at the four corners of the protective door 300 to detect the background sound pressure values of the current environment, and when the waves of the four background sound pressure values are ±5% or less, the average value is calculated. This is the set threshold for the reference sound pressure. The sampling frequency of the four analog microphone linear arrays 301 is 100kHz, and the sound pressure receiver 303 includes a power supply module and a wireless transmission module, and is attracted to the protective door 300 by a magnet, and the background sound pressure of the environment collected by the wireless transmission module. The value is transmitted to computer 305. A pulsed ultrasound generator 302 is placed on one side of the guard door to transmit pulsed ultrasound signals at predetermined time intervals, and on the other side of the guard door, four analog microphone linear arrays 301 are used to transmit pulsed ultrasound signals at various detection distances. Collecting the raw signals of the channels respectively, converting the raw signals of the four channels into four channel voltage signals, transmitting the signal conditioned four channel voltage signals to the computer processing unit 305, and converting the four channel raw signals into four channel voltage signals, Extract feature values and collect images and test distances by camera module and ranging module.

Furthermore, on the other side of the protective door 300, an array detector 304 (including a linear array 301 consisting of four analog microphones, a computer processing unit, a signal conditioning circuit board, a camera module, and a ranging module) is used. Detect the sound pressure value by moving it along the guideline of the video, and measure the sound pressure value to each set leakage grade threshold (add 10%, 30%, 50% of the difference to the set threshold of the reference sound pressure) If the tested sound pressure value exceeds the first class leak threshold, it indicates that there is a leak in the current environment. , perform envelope cross-correlation calculation based on adaptive filtering on the raw signals of the four channels to obtain the delay difference of each channel, and combine these with the test distance and the sound pressure values of the four channels to fuse them. to calculate the three-dimensional spatial coordinates of the leak point. Next, the three-dimensional space coordinates and the image coordinates are mapped to visually superimpose the points indicated by the colored contour lines on the image, and the leakage points are visualized. Visualize positioning results on the human-machine interface.
Example 3

Hereinafter, specific embodiments of the method for actively detecting the airtightness of doors and the position of leakage points according to the present invention will be described in detail.

Step S1: Attach the sound pressure receiver to the four corners of the protective door using magnets, detect the background sound pressure value of the current environment, and transmit it to the computer using wireless communication technology, 29.2 dB, 29 dB, 28.8 dB, respectively. , 29 dB and an average value of 29 dB of four sound pressure values with a wave motion of ±5% or less is set as the reference sound pressure setting threshold.

Step S2: Place a pulsed ultrasonic generator, set its frequency to 40kHz and amplitude to 5V, and transmit a pulsed ultrasonic signal every 1s. Each acoustic signal is collected by the array and converted into a voltage signal, the sampling frequency is set to 100kHz, the signal is conditioned and transmitted to the computer, the sound pressure characteristic values of the four channels are extracted, and the sound pressure characteristic values of the four channels are extracted and processed by the camera module and ranging module. Collect footage and test distance.
Furthermore, extraction of the sound pressure value in step S2 is realized by the following steps.
Step S2.1: Waveform selection and smoothing filtering: The obtained four channel voltage signals are extracted step by step, and for each channel voltage signal, they are sorted according to the amplitude size in the time domain, and the amplitude is the largest. Select a data segment that is 80-90% of the value to form a valid data segment corresponding to each of said channel voltage signals (i.e., exclude other data points), 100 data points per channel data. will be put on hold.
Step S2.2: Perform three spline interpolation operations for each selected valid data segment to increase data sampling points.
Step S2.3: Statistically calculate the frequency distribution of the data, set each peak value of the valid data segment as the voltage characteristic value U of the corresponding channel, and calculate the sound pressure characteristic value SPL of the corresponding channel using the following conversion formula. obtain.

Step S3: Using a detection distance of 100 mm as an example, set a threshold value for each leakage grade.
Further, the setting of the leakage grade threshold in step S3 is realized by the following steps.
Step S3.1: Calculate the average value of the sound pressure feature values of the four channels obtained in step S2.3, obtain the attenuation curve of the sound pressure feature value with the detection distance, and when the detection distance is 100 mm. , the sound pressure feature average value is 55.6 dB.
Step S3.2: At a detection distance of 100 mm, subtract the sound pressure characteristic value from the reference value obtained in step S1 to obtain 26.6 dB, and add 10%, 30%, and 50% of the difference to the reference value, respectively. The summed values are the first class leakage threshold, the second class leakage threshold, and the third class leakage threshold, that is, the three class leakage thresholds are 31.66 dB, 36.98 dB, and 42.3 dB, respectively, and the three classes are the leakage thresholds. Represents ignorable, leakage not ignorable (immediate repair not required), and leakage not ignorable (immediate repair required).

Step S4: Place a pulsed ultrasonic generator on one side of the protective door, set the frequency to 40kHz and the amplitude to 5V, and transmit a pulsed ultrasonic signal every 1 s, and transmit the pulsed ultrasonic signal by an array detector on the other side of the protective door. When the test distance is 100mm, the sound pressure value to be tested is 34.7dB, which exceeds the first class leakage threshold, indicating that there is leakage in the current environment, and the test distance is 100mm. Then, an envelope cross-correlation calculation based on adaptive filtering is performed on the raw signals of the four channels obtained in step S2 to obtain the delay difference of each channel, and the result is calculated based on the test distance and the sound pressure values of the four channels. These are combined and fused to calculate the three-dimensional spatial coordinates of the leak point.
Furthermore, in step S4, calculating the three-dimensional spatial coordinates of the leak point by fusing these is realized by the following steps.
Step S4.1: Extract valid data segments from the raw signals of the four channels obtained in step S2, and compare the difference in the average amplitude values of the two data segments (from the same channel) for every 100 data points. Then, find the data segment where the pulse signal appeared, and take 100 data points before and after the data segment, making a total of 300 data points.
Step S4.2: Extract the envelope for the selected data segment, perform the cross-correlation calculation on the two channel envelopes, take channel 1 and channel 2 as an example, and perform the cross-correlation calculation on the two channels. ceremony,
and
Here, x ₁ (n) and x ₂ (n) are the signal arrays of channel 1 and channel 2, respectively, and τ is the number of delay points,
The calculated number of delay points between channel 2 and channel 1 is τ ₁₂ =12, and similarly, the number of delay points between channel 3 and channel 1 and the number of delay points between channel 4 and channel 1 are calculated. be able to.
Step S4.3: Input the two channel signal envelopes into the adaptive filter, assign a weight vector to one of the channels, calculate the iteration error until the iteration error is minimized, and constantly update the weighting coefficient. When the correlation between the two channels is maximum, the formula based on the adaptive filtering algorithm is
and
Here, w(n) represents the weighting coefficient, e(n) represents the repetition error each time, and y ₁ (n) is the array obtained by multiplying the array of channel 1 by the weighting coefficient.
At this time, the number of two channel delay points τ ₁₂ =6 is calculated again using the formula in step S4.2, and the number of delay points obtained in step S4.2 is calculated before passing through the adaptive filter, and the number of delay points obtained in step S4.2 is calculated before passing through the adaptive filter. After 3, the iteration error is minimum due to continuous updating, so the number of delay points also changes when the error is minimum, and the number of delay points τ ₁₂ =6 is obtained through the filtering algorithm. After the feature transformation is performed, the arrival time difference Δt ₁₂ = 60 μs between channel 2 and channel 1 is obtained, which, when multiplied by the sound speed of 343 m/s, becomes the arrival distance difference between channel 2 and channel 1 Δd ₁₂ = 20 .58 mm, which gives, by analogy, a difference in arrival distance between channel 3 and channel 1 Δd ₁₃ =24.35 mm, and a difference in arrival distance between channel 4 and channel 1 Δd ₁₄ =13.67 mm It is.
Step S4.4: Perform feature transformation on the test sound pressure values obtained for the four channels to obtain three arrival distance ratios corresponding to the four channels, that is, the attenuation curves of step S3.1. First, the test sound pressure values of the four channels are converted into four corresponding distances, and then, among the four distances, each of the three distances corresponding to the three channels and the remaining Calculate the ratio of one channel to another corresponding distance, for example, the arrival distance ratio k ₁₂ =1.18 between channel 2 and channel 1, and the arrival distance ratio k between channel 3 and channel 1. ₁₃ = 1.23, and the arrival distance ratio k ₁₄ = 1.07 between channel 4 and channel 1.
Step S4.5: A first spherical surface about the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance differences, with the test distance as one component of the three-dimensional spatial coordinates of the leak point. Create simultaneous coordinate equations, create a second simultaneous spherical coordinate equation for the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance ratios, and create a second simultaneous equation for the spherical coordinates with the first simultaneous equation From the results of the second simultaneous spherical coordinate equations, positioning coordinates (11.3 mm, 9.78 mm, 102.05 mm) are determined using a fusion algorithm.
In other words, with the coordinates of the leak point as an unknown, create simultaneous equations based on the arrival distance difference and arrival distance ratio, obtain two sets of three-dimensional space coordinate data, and then calculate the average value of the two data. , calculate the final three-dimensional spatial position of the leak point.

Step S6: Map the positioning coordinates (that is, three-dimensional space coordinates) calculated in step S4 and the image coordinates, and visually superimpose the points indicated by the colored contour lines on the image to visualize the leakage points.
Furthermore, the mapping process in step S6 is realized by the following steps.
Step S6.1: Divide the video screen into 320*180 grids, and make each pixel point correspond to each spatial coordinate.
Step S6.2: With the center of the video screen as the origin, move the reference target corresponding to the center of the linear array, and establish a mapping relationship between the number of interval points and the distance.
Here, the interval point number is the number of pixels corresponding to a unit distance in the abscissa axis direction or the ordinate axis direction on the video screen. For example, if the test distance is 100 mm (102.05 mm corresponding to the three-dimensional spatial coordinates (11.3 mm, 9.78 mm, 102.05 mm) calculated in step S4.5 is approximately 100 mm), the interval points The mapping relationship between and distance is N=2*d.
Step S6.3: According to the distance mapping relationship, the three-dimensional spatial coordinates calculated in step S4.5 are converted into pixel coordinate points (23, 20) and superimposed on the screen.
If the test distance is determined to be 100 mm in step S6.2, the mapping relationship between the number of interval points and the distance is N=2*d, and the three-dimensional spatial coordinates (11.3 mm, By substituting the distance 11.3 mm on the abscissa axis (9.78 mm, 102.05 mm) and the distance 9.78 mm on the ordinate axis into the above mapping relationship, the coordinate point (22.6, 20) is determined and the pixel point Since there are only integers, the pixel coordinate point (23, 20) can be obtained by rounding.

The present invention further provides an active detection system for leak point location, the active detection system being arranged at four corners of the protective door to detect background sound pressure values of the current environment, and detecting the background sound pressure values of the current environment. four sound pressure receivers whose average value is a set threshold value of the reference sound pressure; and a pulsed ultrasonic generator that is placed on one side of the protective door and transmits a pulsed ultrasonic signal at predetermined time intervals; Collect raw signals of four channels at various detection distances, convert the raw signals of the four channels into four channel voltage signals, and calculate the sound pressure feature values of the four channels based on the four channel voltage signals. an array detector that extracts and collects images and test distances related to the protective door; and a setting device that sets a threshold for each leakage class based on the sound pressure feature values of the extracted four channels and the set threshold of the reference sound pressure. and, the array detector further detects a sound pressure value on the other side of the protective door along the guideline of the image, obtains sound pressure values of four channels, and detects sound pressure values of the four channels. Comparing the average value of the sound pressure values to be tested with the threshold value of each leakage class, if the average value of the sound pressure values to be tested exceeds the first class leakage threshold, indicating that a leak exists in the current environment, Performing an envelope cross-correlation operation based on adaptive filtering on the raw signals of the four channels to obtain three delay differences between three channels of the four channels and the remaining one channel, and performing the test. In combination with the distance and the tested sound pressure values of the four channels, these are fused and used to calculate the three-dimensional spatial coordinates of the leak point.

The steps performed by the configuration device may be performed by a computer.

A method for actively detecting the airtightness of doors and the location of leakage points according to an embodiment of the present invention includes the following steps S1 to S4.

Step S1: Place sound pressure receivers at the four corners of the protective door to detect the background sound pressure value of the current environment, and if the wave of the four background sound pressure values is less than ±5%, calculate the average of these The value is set as the reference sound pressure threshold.

Step S2: Place a pulsed ultrasonic generator on one side of the protective door to transmit pulsed ultrasonic signals at predetermined time intervals, and collect raw signals of four channels by four analog microphone linear arrays at various detection distances. respectively collected, converted into voltage signals, signal conditioned and transmitted to the computer processing unit, extracting sound pressure feature values of four channels, and collecting images and current test distance by camera module and ranging module. .

Step S3: Set a threshold value for each leakage grade based on the extracted sound pressure feature values of the four channels.

Step S4: Use the array detector on the other side of the protective door to detect the sound pressure value by moving it along the guideline of the image, compare the test sound pressure value with each leakage class threshold, and If the value exceeds the first-class leakage threshold, it indicates that there is leakage in the current environment, and the raw signals of the four channels are subjected to envelope cross-correlation calculation based on adaptive filtering to obtain the delay difference of each channel. In combination with the ratio of test distance and sound pressure amplitude, these are fused to calculate the three-dimensional spatial coordinates of the leak point.

Preferably, the following steps S5 and S6 are further included.

Step S5: If the sound pressure value to be tested is below the first class leakage threshold and the current amount of environmental leakage is small, move the array detector in the space so that the sound pressure value to be tested exceeds the first class leakage threshold. If so, step S4 is repeated.

Step S6: The three-dimensional space coordinates and the image coordinates are mapped to visually superimpose the points indicated by the colored contour lines on the image, thereby visualizing the leakage points.

Preferably, in step S2, extracting the sound pressure feature values of the four channels includes the following steps S2.1 to S2.3.
Step S2.1: Extract the obtained four channel voltage signals step by step, sort them according to the amplitude size in the time domain, and select the data segment whose amplitude is 80-90% of the maximum value. , eliminate other data points.
Step S2.2: Perform three spline interpolation operations on the selected data segment to increase data sampling points.
Step S2.3: Statistically calculate the frequency distribution of the data, take the peak value as the voltage characteristic value U of this channel, and use the conversion formula from voltage to sound pressure.
is used to obtain the sound pressure feature value SPL of this channel.

Preferably, in step S3, setting a threshold value for each leakage grade based on the extracted sound pressure feature values of the four channels includes step S3.1 and step S3.2 as described below.
Step S3.1: Calculate the average value of the sound pressure feature values of the four channels obtained in step S2, and obtain an attenuation curve according to the detection distance of the sound pressure feature value.
Step S3.2: At each test distance, calculate the difference between the sound pressure feature value and the reference sound pressure setting threshold obtained in step S1, and set the reference sound pressure setting threshold to 10%, 30%, 50% of the difference. The sum of the percentages is the first-class leak threshold, second-class leak threshold, and third-class leak threshold, respectively.The first-class leak threshold indicates that the leak can be ignored, and the second-class leak threshold indicates that the leak cannot be ignored, but there is no need to repair it immediately. The third-class leak threshold indicates that the leak cannot be ignored and must be repaired immediately.

Preferably, in step S4, calculating the three-dimensional spatial coordinates of the leakage point includes the following steps S4.1 to S4.5.
Step S4.1: Extract valid data segments from the raw signals of the four channels obtained in step S2, compare the difference in amplitude average values of the two data segments for every 100 data points, and determine whether a pulse signal appears. Find the data segment and take the 100 data points before and after the data segment.
Step S4.2: Extract the envelope for the selected data segment, perform cross-correlation calculation on the two channel envelopes, and the two channel cross-correlation calculation formula is
and
Here, x ₁ (n) and x ₂ (n) are the signal arrays of channel 1 and channel 2, respectively, and τ is the number of delay points.
Step S4.3: Input the two channel envelopes into the adaptive filter, assign a weight vector to one of the channels, and calculate the iterative error until the iterative error is minimized to determine the weighting coefficient based on the adaptive filtering algorithm. At this time, the correlation between the two channels is the maximum, and at this time, the number of delay points of the two channels is calculated using the formula in step S4.2, the characteristic conversion is performed to obtain the arrival time difference, and the sound speed is added to it. Multiply to get the arrival distance difference.
Step S4.4: Perform feature transformation on the sound pressure feature values of the four channels to obtain the arrival distance ratio.
Step S4.5: Taking the test distance as one component of the three-dimensional spatial coordinates of the leakage point, create a simultaneous equation of multidimensional scale spherical coordinates with the center of the linear array as the origin, and use the fusion algorithm to Solve the coordinates.

Preferably, in step S4.4, the sound pressure feature values of the four channels are subjected to feature transformation to obtain the arrival distance ratio. The method includes associating a feature value with one distance and then calculating a ratio.

Preferably, the mapping process in step S6 includes the following steps S6.1 to S6.3.
Step S6.1: Divide the video screen into 320*180 grids, and make each pixel point correspond to each three-dimensional space coordinate.
Step S6.2: With the center of the video screen as the origin and corresponding to the center of the linear array, move the reference target and establish a mapping relationship between the interval points and the test distance.
Step S6.3: Convert the three-dimensional spatial coordinates calculated in step S4.5 into pixel coordinate points according to the mapping relationship of the test distance, and display them in a superimposed manner on the screen.

The method preferably includes the step of performing step S4 by moving to the left or right until the positioning point appears on the screen if it is detected that the leak point exists in the space but is outside the display range of the video screen. further including.

Preferably, the sampling frequency of the four analog microphone linear arrays is 100 kHz, and the sound pressure receiver includes a power supply module and a wireless transmission module, and is attracted to the protective door by a magnet, and the sound pressure receiver is attracted to the protective door by a magnet, and the sound pressure receiver is attached to the protective door by a magnet, and the sound pressure receiver is attached to the protective door by a magnet, and the sound pressure receiver includes a power supply module and a wireless transmission module. The background sound pressure value of is transmitted to the computer.

In the above, the preferred embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the details of the embodiments described above, and the present invention is not limited to the details of the embodiments described above. Various simple modifications can be made to the technical solution of the invention, and all these simple modifications fall within the patent scope of the invention.

Note that the individual specific technical features described in the above-mentioned detailed description may be combined in any appropriate form as long as they do not contradict each other, and in order to avoid unnecessary duplication, in the present invention, The various possible combinations will not be further described.

Further, although the embodiments of the present invention have been shown by way of example, those skilled in the art will be able to make various changes, modifications, substitutions, and variations in these embodiments without departing from the principles and spirit of the present invention. It is understood that the scope of the invention is defined by the appended claims and their equivalents.

Claims (14)

An active detection method for a leak point location, the method comprising:
A step S1 in which a background sound pressure value of the current environment is detected by sound pressure receivers placed at four corners of the protective door, and the average value of the four background sound pressure values is set as a reference sound pressure threshold;
A pulsed ultrasonic generator placed on one side of the protective door transmits a pulsed ultrasonic signal at predetermined time intervals, and raw signals of four channels are collected by an array detector at various detection distances. Step S2 of converting raw signals of channels into four channel voltage signals, extracting sound pressure feature values of four channels based on the four channel voltage signals, and collecting an image and a test distance regarding the protective door;
Step S3 of setting a threshold value for each leakage class based on the extracted sound pressure characteristic values of the four channels and the set threshold value of the reference sound pressure;
On the other side of the protective door, the array detector is moved along the video guideline to detect sound pressure values, and the sound pressure values of the four channels are obtained, and the sound pressure values of the four channels are detected. The average value of the sound pressure values is compared with the threshold value of each leakage class, and if the average value of the sound pressure values to be tested exceeds the first class leakage threshold, it indicates that a leak exists in the current environment, and An envelope cross-correlation operation based on adaptive filtering is performed on the raw signals of the two channels to obtain three delay differences between three of the four channels and the remaining one channel, and the test distance and A method for active detection of a leak point position, comprising: step S4 of calculating three-dimensional spatial coordinates of a leak point by combining and fusing these with the sound pressure values to be tested of the four channels. If the sound pressure value to be tested is below the first class leakage threshold and the amount of leakage in the current environment is small, the analog microphone linear array is moved in space so that the sound pressure value to be tested is equal to or less than the first class leakage threshold. Step S5 of repeating step S4 when the threshold value is exceeded;
The method further includes a step S6 of mapping the three-dimensional space coordinates and image coordinates to visibly superimpose points indicated by colored contour lines on the image to visualize leak points. The active detection method of a leak point position according to claim 1. In step S2, extracting the sound pressure feature values of the four channels is as follows:
The signal-conditioned four channel voltage signals are extracted step by step, and for each channel voltage signal, they are sorted according to the magnitude of the amplitude in the time domain, and the data segments whose amplitude is 80-90% of the maximum value are extracted. step S2.1 of selecting and forming valid data segments corresponding to each of said channel voltage signals;
step S2.2 of increasing the data sampling points by performing three spline interpolation operations for each selected valid data segment;
The frequency distribution of the data is statisticized, each peak value of the valid data segment is taken as the voltage characteristic value U of the corresponding channel, and the conversion formula from voltage to sound pressure is calculated.
3. The active detection method of a leak point position according to claim 2, further comprising step S2.3 of obtaining the sound pressure characteristic value SPL of the corresponding channel using . In step S3, setting a threshold value for each leakage grade based on the extracted sound pressure feature values of the four channels and the set threshold value of the reference sound pressure includes:
Step S3.1 of calculating the average value of the sound pressure feature values of the four channels obtained in step S2 and obtaining an attenuation curve of the sound pressure feature value with the test distance;
At each test distance, the difference between the sound pressure feature value and the reference sound pressure setting threshold obtained in step S1 was calculated, and 10%, 30%, and 50% of the difference were added to the reference sound pressure setting threshold. a first-class leakage threshold, a second-class leakage threshold, and a third-class leakage threshold, respectively, the first-class leakage threshold indicating that leakage can be ignored, and the second-class leakage threshold indicating that leakage cannot be ignored but must be repaired immediately. 4. The leak point location according to claim 3, characterized in that the step S3.2 represents that there is no need, and the third-class leakage threshold represents that the leakage cannot be ignored and needs to be repaired immediately. active detection method. In step S4, calculating the three-dimensional spatial coordinates of the leak point by merging these
Corresponding valid data segments are extracted from the raw signals of the four channels obtained in step S2, and the difference in amplitude average values of two data segments in the same valid data segment is compared for every 100 data points. , step S4.1 of finding a data segment in which a pulse signal appears and taking 100 data points before and after the data segment;
A step of extracting an envelope for each selected data segment and performing a cross-correlation calculation on the two channel envelopes, the cross-correlation calculation formula for the two channels being as follows:
and
Here, x _i (n) and x _j (n) are the signal arrays of channel i and channel j, respectively, i, j = 1, 2, 3, 4, and i and j are not equal, and τ is the delay Step S4.2, which is the score;
Input the two channel envelopes into the adaptive filter, assign a weight vector to one of the channels, calculate the iteration error based on the adaptive filtering algorithm, and constantly update the weight coefficient until the iteration error is minimized. , At this time, the correlation between the two channels is maximum, and the number of delay points of the two channels is calculated using the formula in step S4.2, and three delay points of the three channels and the remaining one channel are obtained. Step S4.3: perform feature transformation on the three delay points to obtain three arrival time differences, and then multiply each of the three arrival time differences by the speed of sound to obtain three arrival distance differences. and,
step S4.4 of performing feature transformation on the tested sound pressure values of the four channels to obtain three arrival distance ratios;
With the test distance as one component of the three-dimensional spatial coordinates of the leak point, a first simultaneous spherical coordinate equation is created for the three-dimensional spatial coordinates with the center of the linear array as the origin based on the three arrival distance differences. Then, based on the three arrival distance ratios, a second simultaneous spherical coordinate equation is created for the three-dimensional spatial coordinates with the center of the linear array as the origin, and the first simultaneous spherical coordinate equation and the second spherical coordinate are 5. The active detection method of a leak point position according to claim 4, further comprising the step of solving the three-dimensional spatial coordinates using a fusion algorithm from the results of the simultaneous equations. In step S4.4, performing feature transformation on the test sound pressure values of the four channels to obtain three arrival distance ratios is as follows:
Using the attenuation curve obtained in step S3.1, first convert the test sound pressure values of the four channels into four corresponding distances, and then convert the three of the four distances. 6. The active detection method of a leak point position according to claim 5, further comprising the step of calculating a ratio between each of the three distances corresponding to a channel and another distance corresponding to the remaining one channel. The mapping process in step S6 is
step S6.1 of dividing the video screen into 320*180 grids and making each pixel point correspond to each three-dimensional space coordinate;
With the center of the video screen as the origin, the origin is mapped to the center of the linear array, a reference target is moved, and an interval point number is the number of pixels corresponding to a unit distance in the abscissa axis direction or the ordinate axis direction in the video screen. step S6.2 of establishing a mapping relationship between and a test distance;
Converting the three-dimensional space coordinates calculated in step S4.5 into pixel coordinate points according to the established mapping relationship, and step S6.3 superimposing and displaying the pixel coordinate points on the screen. The active detection method of a leak point position according to claim 6. If it is detected that the leakage point exists in the space but is outside the display range of the video screen, the method further includes the step of moving left or right until the positioning point appears on the screen and performing step S4. The active detection method for a leak point position according to claim 7. The leak of claim 1, wherein the array detector includes a linear array of four analog microphones, a computer processing unit, a signal conditioning circuit board, a camera module, and a ranging module. Active detection method for point positions. Claim 9, wherein the sampling frequency of the linear array consisting of the four analog microphones is 100 kHz, and the sound pressure receiver includes a power supply module and a wireless transmission module, and is attracted to the protective door by a magnet. Active detection method for leak point location described in . The step of setting the average value of the four background sound pressure values as a reference sound pressure setting threshold is carried out when the waves of the four background sound pressure values are within a preset range. The active detection method of a leak point position according to claim 1. An active detection system for leak point location, the system comprising:
four sound pressure receivers arranged at four corners of the protective door to detect a background sound pressure value of the current environment and set an average value of the four background sound pressure values as a reference sound pressure setting threshold;
a pulsed ultrasonic generator that is placed on one side of the protective door and transmits a pulsed ultrasonic signal at predetermined time intervals;
Collect raw signals of four channels at various detection distances, convert the raw signals of the four channels into four channel voltage signals, and calculate the sound pressure feature values of the four channels based on the four channel voltage signals. an array detector that extracts and collects images and test distances regarding the protective door;
a setting device that sets a threshold value for each leakage class based on the extracted sound pressure characteristic values of the four channels and the set threshold value of the reference sound pressure,
The array detector further detects sound pressure values along the guidelines of the image on the other side of the protective door, obtains the sound pressure values of the four channels, and detects the sound pressure values of the four channels. If the average value of the tested sound pressure values exceeds the first class leakage threshold, it indicates that a leak exists in the current environment, and An envelope cross-correlation operation based on adaptive filtering is performed on the raw signal to obtain three delay differences between three of the four channels and the remaining one channel, and the test distance and the four What is claimed is: 1. An active detection system for a leak point position, characterized in that the active detection system is used to calculate three-dimensional spatial coordinates of a leak point by combining and fusing these with a sound pressure value to be tested of a channel. 12. The leak of claim 11, wherein the array detector includes a linear array of four analog microphones, a computer processing unit, a signal conditioning circuit board, a camera module, and a ranging module. Active detection system for point position. 14. The sampling frequency of the four analog microphone linear arrays is 100kHz, the sound pressure receiver includes a power supply module and a wireless transmission module, and is attracted to the protective door by a magnet. Active detection system for leak point location.