Signal processing method and device of air tightness detection device and computer readable storage medium

Abstract

The invention discloses a signal processing method and device for an air tightness detection device and a computer readable storage medium, and the method comprises the steps: extracting a current pressure value after zero point tracking verification at a current moment, and calculating a pressure change rate according to a preorder pressure value; calculating a dynamic threshold value at the current moment according to the pressure change rate, the gain coefficient and the basic threshold value; judging whether the absolute value of the pressure difference between the current pressure value and the final pressure output value at the previous moment is greater than the current dynamic threshold value or not; if yes, the final pressure output value at the previous moment is used as the first-stage filtering output at the current moment, and if not, the current pressure value is used as the first-stage filtering output at the current moment; performing median filtering on the first-stage filtering output to obtain second-stage filtering output; and performing first-order lagging filtering on the second-stage filtering output to obtain third-stage filtering output, and taking the third-stage filtering output as a final pressure output value at the current moment. According to the invention, pulse interference can be effectively filtered.

Description

Technical Field

[0001] This invention relates to the field of airtightness testing, and more particularly to a signal processing method and system for an airtightness testing device. Background Technology

[0002] Air tightness testers, also known as air leak testers, are widely used in automotive parts, medical devices, consumer electronics and other fields. The pressure sensor is the data acquisition device and the electro-proportional valve is the pressure regulating actuator. These two parts are the core components of the instrument, and their accuracy, zero drift and stability have an important impact on the test.

[0003] As precision instruments, airtightness testing instruments have their sensors calibrated at the factory. However, when installed on the production line, random noise and pulse interference in the sampling signal cause pressure readings to fluctuate, affecting the threshold setting for judging the test results and reducing the resolution and reliability of the instrument. Existing filtering methods use a single threshold, which cannot adapt to the dynamic pressure changes in airtightness testing. This can lead to the contradiction of either filtering out valid signals or missing interference signals, and it cannot effectively filter out pulse interference. Summary of the Invention

[0004] This invention provides a signal processing method and system for an airtightness detection device, which can solve the problem that existing airtightness detection devices cannot effectively filter pulse interference.

[0005] An embodiment of the present invention provides a signal processing method for an airtightness detection device, comprising: During the airtightness test, the current pressure value after zero-point tracking verification is extracted, and the pressure change rate at the current moment is calculated based on the current pressure value and the previous pressure value. The dynamic threshold at the current moment is calculated based on the pressure change rate, the preset gain coefficient, and the preset base threshold. Determine whether the absolute value of the pressure difference between the current pressure value and the final pressure output value at the previous moment is greater than the dynamic threshold. If yes, then the final pressure output value of the previous moment is used as the first-level filter output of the current moment; otherwise, the current pressure value is used as the first-level filter output of the current moment. The first-stage filter output is subjected to median filtering to obtain the second-stage filter output; The second-stage filter output is subjected to a first-order lag filter to obtain the third-stage filter output, which is then used as the final pressure output value at the current moment.

[0006] Furthermore, the zero-point tracking verification includes: Each time the power is turned on or the current test circuit is in a pressure-free state for a preset period of time, the atmospheric pressure value of the current environment is collected and the absolute value of the pressure difference between the current atmospheric pressure value and the zero point of the area is calculated; the zero point of the area is determined by manually zeroing the airtightness detection device and then collecting the atmospheric pressure value of the area. If the pressure difference is less than a preset threshold, record the zero-point offset value, and calculate the current pressure value after zero-point tracking and verification based on the original pressure sampling value at the current moment, the zero point, and the zero-point offset value at the previous moment. If the pressure difference is greater than or equal to a preset threshold, the current pressure value after zero-point tracking and verification is calculated based on the original pressure sampling value at the current moment and the zero point.

[0007] Furthermore, the step of calculating the pressure change rate at the current moment based on the current pressure value and the previous pressure sampling value includes: The rate of change of pressure at the current moment can be calculated using the following formula: ; in, The rate of change of pressure at the current moment; This is the current pressure value after zero-point tracking and verification at the current moment; This is the pressure value after zero-point tracking verification at the previous moment; This is the pressure value after zero-point tracking and verification at the previous time.

[0008] Furthermore, the dynamic threshold is calculated using the following formula: ; in, This represents the dynamic threshold at the current moment. The preset base threshold; This is the preset gain coefficient.

[0009] Furthermore, the filter coefficient of the first-order hysteresis filter corresponding to the pressure holding stage in the airtightness testing process is smaller than the filter coefficient of the first-order hysteresis filter corresponding to the inflation and deflation stages.

[0010] Furthermore, it also includes: obtaining the current target pressure value during the inflation phase of the airtightness testing process; Based on the target pressure value, match the corresponding target DA value in the pre-stored DA-pressure relationship table; drive the electric proportional valve according to the target DA value.

[0011] Furthermore, the DA-pressure relationship table is constructed in the following way: different DAs are set, and the electric proportional valves are driven one by one to output several different pressures; the pressure values ​​of the pressure sensors are read, and the pressure values ​​of the pressure sensors are associated with the corresponding DAs to form the DA-pressure relationship table, and the DA-pressure relationship table is stored.

[0012] Furthermore, it also includes: during the pressure holding phase of the airtightness testing process, if the final pressure output value at any moment during the pressure holding phase is inconsistent with the target pressure value, an early warning will be issued.

[0013] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments; An embodiment of the present invention provides an airtightness detection device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the signal processing method of the airtightness detection device according to any embodiment of the present invention.

[0014] Based on the above method embodiments, the present invention provides corresponding computer-readable storage medium embodiments; One embodiment of the present invention provides a computer-readable storage medium, the computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the signal processing method of the airtightness detection device according to any embodiment of the present invention.

[0015] The following beneficial effects can be achieved by implementing the embodiments of the present invention: This invention provides a signal processing method, apparatus, and computer-readable storage medium for an airtightness detection device. During airtightness detection, the method extracts the current pressure value after zero-point tracking verification at the current moment. Based on the current pressure value and the preceding pressure value, it calculates the pressure change rate at the current moment. A dynamic threshold is determined based on the pressure change rate. A first-level filter is performed based on the dynamic threshold, followed by a second-level median filter and a third-level first-order hysteresis filter. Compared with existing technologies, this invention adopts an innovative architecture of dynamic threshold adaptive adjustment and three-level cascaded filtering. Through dynamic threshold calculation, real-time matching between the threshold and the pressure change state is achieved. The second-level median filter eliminates random noise and isolated pulse residues. The third-level first-order hysteresis filter smooths signal fluctuations and improves reading stability. This effectively solves the core contradiction of traditional single-threshold filtering—namely, the misfiltering of effective signals and the leakage of pulse interference—and improves filtering efficiency.

[0016] Furthermore, the difference in altitude and atmospheric pressure between the instrument's manufacturing location and its final usage location can cause zero drift in the sensor, resulting in pressure deviation. Secondly, variations in climate and temperature in the usage area, particularly large diurnal temperature differences, can cause temperature drift in the pressure sensor and electronic pressure regulation device, leading to pressure fluctuations and even exceeding the preset pressure range, triggering alarms. To address this issue, this application incorporates a zero-point tracking and verification mechanism. Each time the instrument is powered on or when the current test circuit is in a pressure-free state for a preset period, the atmospheric pressure of the current environment is collected, and the absolute value of the pressure difference between the current atmospheric pressure and the zero point of the area is calculated. If the pressure difference is less than a preset threshold, the zero-point offset is recorded. The zero point of the area is determined by manually zeroing the airtightness detection device and then collecting the atmospheric pressure value of the area. This effectively combats slow zero-point drift caused by atmospheric pressure changes, temperature fluctuations, and component aging, ensuring the accuracy of electronic pressure control and measurement throughout the instrument's entire lifespan. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a signal processing method for an airtightness detection device according to an embodiment of the present invention. Detailed Implementation

[0018] 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.

[0019] To resolve the above issues, please refer to [link / reference]. Figure 1 An embodiment of the present invention provides a signal processing method for an airtightness detection device, comprising: S1. During the airtightness test, extract the current pressure value after zero-point tracking verification at the current moment, and calculate the pressure change rate at the current moment based on the current pressure value and the previous pressure value.

[0020] In a preferred embodiment, the zero-point tracking verification includes: each time the power is turned on or the current test circuit is in a pressure-free state for a preset period of time, collecting the atmospheric pressure value of the current environment and calculating the absolute value of the pressure difference between the current atmospheric pressure value and the zero point of the area; wherein, the zero point of the area is determined by manually zeroing the airtightness detection device and collecting the atmospheric pressure value of the area; if the pressure difference is less than a preset threshold, recording the zero-point offset value, and calculating the current pressure value after zero-point tracking verification at the previous moment based on the original pressure sampling value at the current moment, the zero point, and the zero-point offset value; If the pressure difference is greater than or equal to a preset threshold, the current pressure value after zero-point tracking and verification is calculated based on the original pressure sampling value at the current moment and the zero point.

[0021] Specifically, because the atmospheric pressure varies with altitude in different regions, the sensor may drift to zero and the pressure may deviate. Therefore, when the airtightness detection device is used in a new region, it needs to be manually zeroed once to collect the atmospheric pressure value of the area to zero.

[0022] Next, the airtightness testing device automatically performs a zero-point calibration each time it is powered on or when the current test circuit is in a pressure-free state for a preset period (e.g., 10 minutes, 20 minutes, or 30 minutes, the specific time is set according to the actual situation). It reads the pressure value through the atmosphere to obtain the current atmospheric pressure value and calculates the absolute value of the difference between the current atmospheric pressure value and the aforementioned zero point. If this absolute value of the pressure difference is less than a preset threshold (e.g., 5 kPa), the difference between the current atmospheric pressure value and the aforementioned zero point is used as the zero-point offset value, and this zero-point offset value is recorded. Then, during airtightness testing, the pressure signal from the sensor at the current moment is converted into an AD raw value (i.e., the aforementioned raw pressure sampling value). The difference between this value and the zero point and the zero-point offset value is calculated to obtain the current pressure value after zero-point tracking and verification. If this absolute value of the pressure difference is not less than the preset threshold, it indicates that the pressure is abnormal. In this case, the zero-point offset value is not introduced to avoid abnormal reference data contamination; the difference between the raw pressure sampling value and the zero point is directly calculated to obtain the current pressure value. This effectively combats slow zero-point drift caused by atmospheric pressure changes, temperature fluctuations, and component aging, ensuring the accuracy of electronic pressure control and measurement throughout the instrument's entire lifespan.

[0023] In a preferred embodiment, calculating the pressure change rate at the current moment based on the current pressure value and the previous pressure sample value includes: The rate of change of pressure at the current moment can be calculated using the following formula: ; in, The rate of change of pressure at the current moment; This is the current pressure value after zero-point tracking and verification at the current moment; This is the pressure value after zero-point tracking verification at the previous moment; This is the pressure value after zero-point tracking and verification at the previous time.

[0024] S2. Calculate the dynamic threshold at the current moment based on the pressure change rate, the preset gain coefficient, and the preset base threshold.

[0025] In a preferred embodiment, the dynamic threshold is calculated using the following formula: ; in, This represents the dynamic threshold at the current moment. The preset base threshold; This is the preset gain coefficient.

[0026] As an illustration, the above k value can be adjusted according to the system's sensitivity to rapid changes. The larger the k value, the more sensitive the threshold is to changes, allowing larger changes to pass through. The typical range is 1.0~3.0, with a reference value of 1.8. It can be determined based on the sensor noise level and the allowable fluctuation range of the system, and is usually the maximum fluctuation range of the static sampling value, with a reference value of 0.3; As can be seen from the above formula, the faster the pressure changes (e.g., during the inflation or deflation phase), the larger the dynamic threshold, thus allowing normal pressure changes to pass through and avoiding misinterpreting valid signals as pulse interference; the slower the pressure changes (e.g., during the pressure holding phase), the smaller the dynamic threshold, thus accurately filtering out minute electromagnetic interference and sensor noise, and preventing interference signals from affecting leak detection.

[0027] S3. Determine whether the absolute value of the pressure difference between the current pressure value and the final pressure output value at the previous moment is greater than the dynamic threshold; if so, use the final pressure output value at the previous moment as the first-level filter output at the current moment; otherwise, use the current pressure value as the first-level filter output at the current moment.

[0028] Specifically, through the first-stage dynamic amplitude limiting filter mentioned above, pulse interference in the pressure signal can be accurately identified and filtered out, while the normal pressure change trend is fully preserved, providing clean input data for subsequent median filtering and first-order hysteresis filtering, ultimately ensuring the accuracy and response speed of airtightness detection.

[0029] Pulse interference in industrial settings (such as electromagnetic interference, solenoid valve start-stop impact, and pipeline vibration) is characterized by large instantaneous jump amplitude and extremely short duration, which can cause irregular sudden changes in the current pressure sampling value.

[0030] By comparing the absolute value of the difference between the current pressure value and the final output value at the previous moment with a dynamic threshold, if the difference exceeds the dynamic threshold, it is determined to be pulse interference. In this case, the final pressure output value at the previous moment is used to replace the current abnormal sampled value, directly truncating the interference spike and preventing the interference from being transmitted to subsequent filtering stages. Otherwise, it is determined to be a valid pressure change, and the current sampled value is directly retained to ensure that the normal pressure trend is not disrupted. This achieves the separation of interference and valid signals.

[0031] S4. Perform median filtering on the first-stage filter output to obtain the second-stage filter output.

[0032] Specifically, the output of the first-stage filter is used as the input of the second-stage filter. A sampling window is set up to sample N times consecutively. The N values ​​are sorted by size, and the median value is taken as the output of the second-stage filter. This step can effectively remove residual spikes. For illustration, N can be 5 or 7. It should be noted that the filter has a buffer or sampling window; when the number of samples is insufficient, the current value or average value can be used directly to fill the gap, avoiding output interruption.

[0033] S5. Perform a first-order lag filter on the second-stage filter output to obtain the third-stage filter output, and use the third-stage filter output as the final pressure output value at the current moment.

[0034] In a preferred embodiment, the filter coefficient of the first-order hysteresis filter corresponding to the pressure holding stage in the airtightness testing process is smaller than the filter coefficient of the first-order hysteresis filter corresponding to the inflation and deflation stages.

[0035] Indicatively, during the pressure stabilization phase (such as the pressure holding phase), the test circuit has closed the inflation / deflation channels. Ideally, the pressure should remain stable, with only sensor inherent noise and minor temperature drift as interference. At this point, a small filter coefficient (generally 0.2-0.4, with a reference value of 0.3) is used for deep smoothing, which greatly suppresses random waves, stabilizes the pressure curve, and prevents minor interference from being misjudged as pressure decay (leakage), thus significantly improving the accuracy of leak detection.

[0036] During periods of rapid pressure change (such as inflation and deflation), the pressure undergoes continuous and significant dynamic changes. Using a larger filter coefficient (typically 0.5-0.7, with a reference value of 0.6) or temporarily disabling the filter can reduce filter lag, prevent the system from continuing to inflate or deflate even when the pressure has reached the target due to smoothing, shorten inflation / deflation time, and improve overall detection efficiency.

[0037] The above three-stage filtering chain combines the advantages of multiple algorithms and can adaptively adjust parameters according to the system's operating state, taking into account both dynamic response speed and static stability, and solving the inherent defects of a single filtering algorithm.

[0038] In a preferred embodiment, the signal processing method of the airtightness detection device further includes: During the inflation phase of the airtightness test, the current target pressure value is obtained; the target DA value is matched with the corresponding target DA value in the pre-stored DA-pressure relationship table according to the target pressure value; and the electric proportional valve is driven according to the target DA value.

[0039] Preferably, the DA-pressure relationship table is constructed in the following way: different DAs are set, and the electric proportional valves are driven one by one to output several different pressures; the pressure values ​​of the pressure sensors are read, and the pressure values ​​of the pressure sensors are associated with the corresponding DAs to form the DA-pressure relationship table, and the DA-pressure relationship table is stored.

[0040] Specifically, the DA-driven electro-proportional valve is configured to output different pressures, with five pressure points set at 10%, 30%, 50%, 70%, and 90% of full scale. After 3-5 seconds for the pressure to stabilize, the pressure sensor value is read, and the corresponding voltage output DA_n (n=1…5) and pressure value P_n (n=1…5) for each group are recorded, forming a correspondence table stored in internal memory such as EPROM or Flash. During normal airtightness testing, the stored DA-pressure relationship table is read, and the current target pressure value P is compared with the table to calculate the appropriate DA value to drive the electro-proportional valve, thus obtaining high-precision pressure.

[0041] In a preferred embodiment, the method further includes: during the pressure holding phase of the airtightness testing process, if the final pressure output value at any point during the pressure holding phase is found to be inconsistent with the target pressure value, an early warning is issued. This embodiment allows for timely detection of leakage risks and provides early warning.

[0042] By implementing the embodiments of the present invention described above, the automatic zero-point tracking mechanism overcomes the long-term drift problem, reduces the inconvenience of frequent manual calibration by users, and lowers maintenance costs. Secondly, by treating the DA output, electro-proportional valve, pressure sensor, and AD acquisition as a whole for zeroing and correction, the instrument's pressure control accuracy and measurement accuracy over a wide temperature range are improved. Furthermore, the three-stage adaptive filter chain can employ optimal filtering strategies under different operating conditions, automatically adjusting filter parameters to effectively suppress various types of noise, outputting a smooth and stable signal, and significantly improving the detection capability of minute leaks.

[0043] Based on the above-described method embodiments, the present invention provides an airtightness detection device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the signal processing method of the airtightness detection device described above.

[0044] One embodiment of this application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the signal processing method of an airtightness detection device as described above.

[0045] The computer device may be a smartphone, tablet, desktop computer, or cloud server, among other computing devices. This computer device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that the figures are merely examples of computer devices and do not constitute a limitation on the computer device. It may include more or fewer components than illustrated, or a combination of certain components, or different components, such as input / output devices, network access devices, etc.

[0046] The processor referred to can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0047] In some embodiments, the memory may be an internal storage unit of the computer device, such as a hard drive or RAM. In other embodiments, the memory may be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory may include both internal and external storage units of the computer device. The memory is used to store the operating system, applications, bootloader, data, and other programs, such as the program code of the computer program. The memory can also be used to temporarily store data that has been output or will be output.

[0048] This application provides a computer program product that, when run on a computer device, enables the computer device to execute the steps described in the various method embodiments above.

[0049] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0050] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A signal processing method for an airtightness detection device, applicable to airtightness detection devices, characterized in that, include: During the airtightness test, the current pressure value after zero-point tracking verification is extracted, and the pressure change rate at the current moment is calculated based on the current pressure value and the previous pressure value. The dynamic threshold at the current moment is calculated based on the pressure change rate, the preset gain coefficient, and the preset base threshold. Determine whether the absolute value of the pressure difference between the current pressure value and the final pressure output value at the previous moment is greater than the dynamic threshold. If yes, then the final pressure output value of the previous moment is used as the first-level filter output of the current moment; otherwise, the current pressure value is used as the first-level filter output of the current moment. The first-stage filter output is subjected to median filtering to obtain the second-stage filter output; The second-stage filter output is subjected to a first-order lag filter to obtain the third-stage filter output, which is then used as the final pressure output value at the current moment.

2. The signal processing method of the airtightness detection device as described in claim 1, characterized in that, The zero-point tracking verification includes: Each time the power is turned on or the current test circuit is in a pressure-free state for a preset period of time, the atmospheric pressure value of the current environment is collected and the absolute value of the pressure difference between the current atmospheric pressure value and the zero point of the area is calculated; the zero point of the area is determined by manually zeroing the airtightness detection device and then collecting the atmospheric pressure value of the area. If the pressure difference is less than a preset threshold, record the zero-point offset value, and calculate the current pressure value after zero-point tracking and verification based on the original pressure sampling value at the current moment, the zero point, and the zero-point offset value. If the pressure difference is greater than or equal to a preset threshold, the current pressure value after zero-point tracking and verification is calculated based on the original pressure sampling value at the current moment and the zero point.

3. The signal processing method of the airtightness detection device as described in claim 2, characterized in that, The step of calculating the pressure change rate at the current moment based on the current pressure value and the previous pressure sample value includes: The rate of change of pressure at the current moment can be calculated using the following formula: ； in, The rate of change of pressure at the current moment; This is the current pressure value after zero-point tracking and verification at the current moment; This is the pressure value after zero-point tracking verification at the previous moment; This is the pressure value after zero-point tracking and verification at the previous time.

4. The signal processing method of the airtightness detection device as described in claim 3, characterized in that, The dynamic threshold is calculated using the following formula: ； in, This represents the dynamic threshold at the current moment. The preset base threshold; This is the preset gain coefficient.

5. The signal processing method of the airtightness detection device as described in claim 4, characterized in that, The filter coefficient of the first-order hysteresis filter corresponding to the pressure holding stage in the airtightness test process is smaller than the filter coefficient of the first-order hysteresis filter corresponding to the inflation and deflation stages.

6. The signal processing method of the airtightness detection device as described in claim 5, characterized in that, Also includes: During the inflation phase of the airtightness test, the current target pressure value is obtained; Match the target DA value to the pre-stored DA-pressure relationship table based on the target pressure value; Drive the electric proportional valve according to the target DA value.

7. The signal processing method of the airtightness detection device as described in claim 6, characterized in that, The DA-pressure relationship table is constructed in the following way: By setting different DAs, the electric proportional valves are driven one by one to output several different pressures; The pressure value of the pressure sensor is read, and the pressure value of the pressure sensor is associated with the corresponding DA to form the DA-pressure relationship table, which is then stored.

8. The signal processing method of the airtightness detection device as described in claim 7, characterized in that, Also includes: During the pressure holding phase of the airtightness test, if the final pressure output value at any point during the pressure holding phase is inconsistent with the target pressure value, an early warning will be issued.

9. An airtightness testing device, characterized in that, The device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the signal processing method of the airtightness detection device as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein when the computer program is executed, it controls the device containing the computer-readable storage medium to perform a signal processing method of the airtightness detection device as described in any one of claims 1 to 8.

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