Multifunctional portable capacitive imaging glass steel storage tank detection system

Abstract

The application provides a multifunctional portable capacitive imaging glass steel storage tank detection system, and belongs to the technical field of nondestructive testing.The technical scheme is as follows: a multifunctional portable capacitive imaging glass steel storage tank detection system, comprising a detection device and a capacitive probe;the detection device comprises a signal generation module, a signal acquisition module, an impedance conversion and preprocessing module and an upper computer;the capacitive probe comprises an excitation plate and a detection plate;the signal generation module generates excitation signals and reference signals;the original detection signals of the detection plate are processed by the impedance conversion and preprocessing module, collected by the signal acquisition module, converted into digital signals and input into the upper computer, and the upper computer calls a double-layer filtering algorithm module to process the input signals to obtain imaging detection signals.The application has the beneficial effects that: the double-layer filtering algorithm is more sensitive and accurate;the capacitive probe and the detection device are separately designed, and are convenient to use.

Description

Technical Field

[0001] This invention relates to the field of nondestructive testing technology, and in particular to a multifunctional portable capacitive imaging fiberglass storage tank inspection system. Background Technology

[0002] Currently, fiberglass reinforced plastic (FRP), as an emerging industrial material, boasts advantages such as high strength, light weight, ease of molding, and low cost, leading to its increasingly widespread applications. For example, FRP is a crucial raw material in industries such as construction, shipbuilding, and oil storage and transportation, particularly in oil fields and oil production plants, where it is used for products like FRP oil pipes, FRP sewage tanks, and FRP water injection pipes. To ensure the quality of FRP components, non-destructive testing is necessary. In the case of severe water leakage in FRP storage tanks at some joint stations in the Shengli Oilfield, effective detection methods for identifying the leak locations are lacking. However, due to the significant differences in properties between glass and metal, conventional methods such as ultrasonic testing, X-rays, and eddy current testing are difficult to apply to FRP products. Therefore, an effective testing system is needed to detect surface and internal defects in non-metallic materials (such as FRP). Summary of the Invention

[0003] To address the problems in the prior art, the present invention aims to provide a multifunctional portable capacitive imaging fiberglass storage tank inspection system. This system incorporates a circuit module and a dual-mode filtering algorithm module specifically designed for the characteristics of the detection signal, enabling the detection of surface and internal defects in non-metallic materials (such as fiberglass).

[0004] This invention is achieved through the following technical solution: a multifunctional portable capacitive imaging fiberglass storage tank inspection system, comprising an inspection device and a capacitance probe; the inspection device includes a signal generation module, a signal acquisition module, an impedance transformation and preprocessing module, and a host computer; the capacitance probe includes an excitation plate and a detection plate arranged on the same plane with a spacing.

[0005] The signal generation module simultaneously generates an excitation signal and a reference signal. The excitation signal is transmitted to the excitation electrode plate via an electrical connection. The original detection signal generated by the detection electrode plate is amplified and filtered by the impedance transformation and preprocessing module to generate an analog detection signal. The analog detection signal and the reference signal are acquired in real time by the signal acquisition module and converted into a digital detection signal DS and a digital reference signal RS by an A / D converter. The digital detection signal DS and the digital reference signal RS are input to the host computer. The host computer calls the dual-layer filtering algorithm module to process the digital detection signal DS and the digital reference signal RS, and finally obtains the imaging detection signal VS.

[0006] This system adopts a modular design concept. The capacitance probe, signal generation module, impedance transformation and preprocessing module, and signal acquisition module are all independent and replaceable modules. When a new replacement is available or a certain part malfunctions, it will not affect the use of other parts. Only the corresponding module needs to be replaced.

[0007] Furthermore, the impedance transformation and preprocessing module consists of a high-gain multi-channel amplification stage, an anti-power frequency filter stage, and a noise removal stage. It can amplify the target frequency components in the signal a second time and effectively attenuate the 50Hz power frequency signal and non-target frequency components. The original detection signal is a charge signal, which is transformed into a voltage signal proportional to its charge amount by the impedance transformation and preprocessing module and output with low output impedance. Since the original detection signal is relatively weak and conventional operational amplifiers cannot process it, the front-end uses an LPC662 chip, utilizing its extremely low bias current characteristics to achieve a million-fold signal gain. The anti-power frequency filter removes the strong 50Hz power frequency signal from the amplified signal, and together with the noise removal stage, achieves secondary amplification of the desired frequency components and effective attenuation of non-target frequency components.

[0008] Furthermore, the dual-layer filtering algorithm module includes a phase-sensitive detection algorithm module and a cross-correlation algorithm module. The digital detection signal DS and the digital reference signal RS are respectively subjected to phase-sensitive detection operation by the phase-sensitive detection algorithm module and cross-correlation operation by the cross-correlation algorithm module. Then, the output results of the two algorithm modules are processed by the root mean square algorithm to obtain the imaging detection signal VS.

[0009] Furthermore, the specific process of the phase-sensitive detection algorithm module includes the following steps:

[0010] S1, the phase-sensitive detection algorithm module discretizes the digital reference signal RS to generate a discrete reference signal and stores it in the array [rs]; at the same time, the cross-correlation algorithm module discretizes the digital detection signal DS to generate a discrete reference signal and stores it in the array [ds].

[0011] S2, the phase-sensitive detection algorithm module generates a square wave signal SQ with a 90° phase shift based on the discrete reference signal and stores it in the input array [sq].

[0012] S3, using the square wave signal SQ as a reference, perform phase-sensitive detection processing on the discrete detection signal, then perform integral filtering to obtain the first detection signal R1, and store it in the array [r1];

[0013] S4, the cross-correlation algorithm performs cross-correlation operation on the discrete reference signal and the discrete detection signal, and after integral filtering, obtains the second detection signal R2 and stores it in the array [r2].

[0014] S5, perform root mean square algorithm processing on the first detection signal R1 and the second detection signal R2 to generate the imaging detection signal VS, and store it in the array [vs].

[0015] The array operations involved are all performed on the elements in the array according to the sequence. For example, "if [rs]>0, then [sq]=1, if [rs]<=0, then [sq]=-1" is equivalent to "assuming [rs]=[a1, a2, ..., an], [sq]=[b1, b2, ..., bn], if a1>0, then b1=1, if a1<0, then b1=-1";

[0016] Furthermore, S3 specifically involves: processing the detection signal DS in real time based on the square wave signal corresponding array [sq], and storing the result in the array [ps]. That is, if [sq] > 0, then [ps] = [ds], and if [sq] <= 0, then [ps] = - [ds]. Then, the array [ps] is subjected to integral filtering processing, and the results are stored in the array [r1] in sequence, thereby obtaining the array [r1] corresponding to the first detection signal R1.

[0017] Furthermore, the cross-correlation operation in S4 specifically involves multiplying the corresponding data in array [rs] and array [ds] and storing the result in array [cc]. The array [cc] is also subjected to integral filtering, and the result is stored in array [r2], thereby obtaining the detection signal array [r2] after cross-correlation algorithm processing.

[0018] Furthermore, the capacitive probe also includes a protective shell with a scanning port at the bottom. A printed circuit board is embedded in the scanning port. The excitation electrode and the detection electrode are symmetrically arranged on the printed circuit board. An insulating protective layer is provided on the protective shell and below the printed circuit board. The insulating protective layer can cover the scanning port.

[0019] Furthermore, the excitation electrode and the detection electrode are configured as interdigitated electrode plates or back-to-back isosceles triangular electrode plates; the back-to-back arrangement of triangular electrode plates enables defect detection; the interdigitated electrode plates enable aging detection.

[0020] Furthermore, four rollers are symmetrically arranged at the bottom of the protective shell and around the periphery of the scanning port.

[0021] Furthermore, the detection device includes an expansion dock, which is integrated with the host computer. All other modules are located within the expansion dock, which is equipped with a connector capable of connecting the capacitance probe.

[0022] Furthermore, the connector uses a BNC interface. The excitation plate and detection plate of the capacitor probe are connected to the BNC interface via signal lines, thereby connecting the excitation plate and detection plate to the corresponding modules of the detection device;

[0023] To facilitate portability and on-site operation, the host computer is a portable computer, and the imaging detection signal can be displayed on the portable computer's screen in real time.

[0024] The beneficial effects of this invention are as follows: This invention has designed a circuit module and a dual-mode filtering algorithm module specifically for the characteristics of the detection signal, which can detect surface and internal defects of non-metallic materials such as fiberglass and present the detection signal in a visual manner; the capacitance probe uses different forms of excitation plates and detection plates to detect defects and aging respectively; the detection device and the capacitance probe are set separately, and all modules of the detection system are packaged in an integrated portable computer with an expansion dock, which is convenient for carrying and on-site operation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram and wiring diagram of the overall structure of the present invention;

[0026] Figure 2 This is a flowchart of the two-layer filtering algorithm module of the present invention;

[0027] Figure 3 This is a capacitance imaging detection amplitude diagram of the present invention;

[0028] Figure 4 This is an amplitude diagram of capacitive imaging for water seepage detection according to the present invention;

[0029] Figure 5 The capacitance value is detected by the aging sensor of this invention.

[0030] The attached diagram is labeled as follows: 1. Capacitance probe; 2. Test object; 3. Signal generation module; 4. Signal acquisition module; 5. Impedance transformation and preprocessing module; 6. Host computer. Detailed Implementation

[0031] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0032] Example 1, as Figure 1-2 As shown, the present invention is achieved through the following technical solution: a multifunctional portable capacitive imaging fiberglass storage tank inspection system, including a detection device and a capacitance probe 1; the detection device includes a signal generation module 3, a signal acquisition module 4, an impedance transformation and preprocessing module 5, and a host computer 6; the capacitance probe 1 includes an excitation plate and a detection plate arranged on the same plane with a spacing.

[0033] The signal generation module 3 simultaneously generates an excitation signal and a reference signal. The excitation signal is transmitted to the excitation electrode plate via an electrical connection. The original detection signal generated by the detection electrode plate is amplified and filtered by the preprocessing module 5 after impedance transformation to generate an analog detection signal. The analog detection signal and the reference signal are acquired in real time by the signal acquisition module 4 and converted into a digital detection signal DS and a digital reference signal RS by an A / D converter. The digital detection signal DS and the digital reference signal RS are input to the host computer 6. The host computer 6 calls the dual-layer filtering algorithm module to process the digital detection signal DS and the digital reference signal RS, and finally obtains the imaging detection signal VS.

[0034] Based on practical engineering applications, this system measures the impedance value of a flat plate resistor to detect surface and internal defects in metallic / non-metallic materials (such as fiberglass). The impedance value is proportional to the distance between the capacitance probe 1 and the tested object 2. In addition to the frictionless and non-destructive characteristics common to general non-contact instruments, it also boasts advantages such as a high signal-to-noise ratio, high sensitivity, low zero drift, wide frequency response, low nonlinearity, good accuracy and stability, strong anti-electromagnetic interference capability, and ease of use. The measurement system is highly sensitive to changes in the dielectric within the measurement range. When detecting leaks in fiberglass storage tanks, the high distortion rate of the water medium by the capacitance probe 1 enables precise and rapid measurement of minute capacitance, quickly and accurately detecting leaks.

[0035] This system adopts a modular design concept. The capacitance probe 1, signal generation module 3, impedance transformation and preprocessing module 5, and signal acquisition module 4 are all independent and replaceable modules. When a new replacement is available or a certain part has a problem, it will not affect the use of other parts. Only the corresponding module needs to be replaced.

[0036] Furthermore, the impedance transformation and preprocessing module 5 consists of a high-gain multi-stage amplification stage, an anti-power frequency filter stage, and a noise removal stage. It can amplify the target frequency components in the signal a second time and effectively attenuate the 50Hz power frequency signal and non-target frequency components. The original detection signal is a charge signal, which is transformed into a voltage signal proportional to its charge amount by the impedance transformation and preprocessing module 5 and output with low output impedance. Since the original detection signal is relatively weak and conventional operational amplifiers cannot process it, the front-end uses an LPC662 chip, utilizing its extremely low bias current characteristics to achieve a million-fold signal gain. The anti-power frequency filter removes the strong 50Hz power frequency signal from the amplified signal, and together with the noise removal stage, achieves secondary amplification of the desired frequency components and effective attenuation of non-target frequency components.

[0037] Furthermore, the dual-layer filtering algorithm module includes a phase-sensitive detection algorithm module and a cross-correlation algorithm module. The digital detection signal DS and the digital reference signal RS are respectively subjected to phase-sensitive detection operation by the phase-sensitive detection algorithm module and cross-correlation operation by the cross-correlation algorithm module. Then, the output results of the two algorithm modules are processed by the root mean square algorithm to obtain the imaging detection signal VS.

[0038] Furthermore, the specific process of the phase-sensitive detection algorithm module includes the following steps:

[0039] S1, the phase-sensitive detection algorithm module discretizes the digital reference signal RS to generate a discrete reference signal and stores it in the array [rs]; simultaneously, the cross-correlation algorithm module discretizes the digital detection signal DS to generate a discrete reference signal and stores it in the array [ds]; wherein, the reference signal emitted by the signal generation module 3 is a sinusoidal reference voltage signal with a frequency of f0 Hz and a period of T0; the discretization sampling frequency is f Hz (100kHz). <f<1MHz,f> f0), the sampling period is T, the sampling time interval is t0, N is the number of real-time samples, and the discretized samples are stored in the array [rs];

[0040] Let the reference signal be: ;

[0041] After sampling and discretization, [rs] is:

[0042]

[0043] The detection signal is recorded as: ;

[0044] After sampling and discretization, [ds] is:

[0045] In the formula: —At any time when sampling begins —Sampling interval, ƒ—Sampling frequency;

[0046] S2, the phase-sensitive detection algorithm module generates a square wave signal SQ with a 90° phase shift based on the discrete reference signal and stores it in the input array [sq]. Specifically, it judges the array [rs] corresponding to the acquired real-time reference voltage signal. If [rs] > 0, then [sq] = 1; if [rs] <= 0, then [sq] = -1. When N > T0 / (4*t0) + 1, the obtained F1 square wave signal is stored in the array [sq], thereby advancing the phase of [sq] by 90° compared to [rs].

[0047] in

[0048] S3, using the square wave signal SQ as a reference, perform phase-sensitive detection processing on the discrete detection signal, then perform integral filtering to obtain the first detection signal R1, and store it in the array [r1];

[0049] S4, the cross-correlation algorithm performs cross-correlation operation on the discrete reference signal and the discrete detection signal, and after integral filtering, obtains the second detection signal R2 and stores it in the array [r2].

[0050] S5, perform root mean square algorithm processing on the first detection signal R1 and the second detection signal R2 to generate the imaging detection signal VS, and store it in the array [vs].

[0051] Furthermore, S3 specifically involves: using the square wave signal corresponding to the array [sq] as a reference to process the detection signal DS in real time, and storing the result in the array [ps]. That is, if [sq] > 0, then [ps] = [ds], and if [sq] <= 0, then [ps] = - [ds]. Then, the array [ps] is subjected to integral filtering processing.

[0052]

[0053] The integral filtering of array [ps] is performed as follows: Let the integration interval be [T0, T1], where T0 is a certain moment after the start of sampling, T1 - T0 = ΔT, and ΔT is selected as an integer multiple of the sampling signal period. Multiply each data point in array [ps] by the sampling time interval t0 and sum them, then divide by ΔT. Store the result in array [r1]. Integrate and divide by ΔT once for each new sampled data point, and store the result sequentially in [r1]. This yields array [r1] corresponding to the first detected signal R1.

[0054]

[0055] In the formula:

[0056] — ,

[0057] n — satisfies ,

[0058] Furthermore, the cross-correlation operation in S4 specifically involves multiplying the corresponding data in array [rs] and array [ds], and storing the result in array [cc].

[0059]

[0060] The array [cc] is also subjected to integral filtering, and the results are stored sequentially in the array [r2], thus obtaining the detection signal array [r2] after cross-correlation algorithm processing:

[0061] Specifically, S5 involves squaring the elements corresponding to arrays [r1] and [r2], summing them, taking the square root of the sum, dividing by 2, and storing the results sequentially into array [vs].

[0062]

[0063] By drawing the elements in the array [vs] in real time, a waveform can be displayed on the display terminal.

[0064] In this array, the lengths of the arrays [rs], [sq], [ds], [ps], and [cc] are n, and the lengths of the arrays [r1] and [r2] are m and n, respectively, where m is an integer multiple of the sampling frequency f and m >> n. In the above arrays, each time a number is sampled, the newly sampled data occupies the first position in the array, and the old data is shifted one position to the right. When the number of samples exceeds the length of the array, the last data in the array is discarded.

[0065] In Embodiment 2, based on Embodiment 1, the capacitive probe 1 further includes a protective shell with a scanning port at the bottom. A printed circuit board is embedded in the scanning port. The excitation electrode and the detection electrode are symmetrically arranged on the printed circuit board. An insulating protective layer is provided on the protective shell and below the printed circuit board. The insulating protective layer can cover the scanning port.

[0066] Shielding electrodes are provided between the excitation electrode and the detection electrode, as well as along the edges of the protective shell and the printed circuit board. The protective shell is a metal shell, and the shielding electrodes are grounded through the protective shell.

[0067] Furthermore, the excitation electrode and the detection electrode are configured as interdigitated electrode plates or back-to-back isosceles triangular electrode plates; the back-to-back arrangement of triangular electrode plates enables defect detection; the interdigitated electrode plates enable aging detection.

[0068] Furthermore, four rollers are symmetrically arranged at the bottom of the protective shell and around the periphery of the scanning port.

[0069] In Example 3, based on Example 2, the detection device further includes an expansion dock, which is integrated with the host computer 6. All other modules are located within the expansion dock, which is equipped with a connector capable of connecting the capacitance probe 1.

[0070] Furthermore, the connector uses a BNC interface. The excitation plate and detection plate of the capacitor probe are connected to the BNC interface via signal lines, thereby connecting the excitation plate and detection plate to the corresponding modules of the detection device;

[0071] To make it more portable and easier to operate on-site, the host computer 6 is a portable computer, and the imaging detection signal can be displayed on the monitor of the portable computer in real time.

[0072] Specifically, the signal generation module 3 transmits the excitation signal to the excitation plate of the capacitor probe 1 through the external BNC interface line of the expansion dock, generating an electric field on the test object 2. At the same time, the signal generation module 3 transmits the reference signal to the signal acquisition module 4. After the detection plate detects the weak charge signal generated by the defect, it is connected to the impedance transformation and preprocessing module 5 through the BNC interface of the expansion dock. The weak charge signal is transformed into a voltage signal proportional to its charge amount, i.e., an analog detection signal, and output to the signal acquisition module 4 in the form of low output impedance. The signal acquisition module 45 acquires the reference signal and the detection signal and transmits them to the portable computer. The portable computer calls the dual-layer filtering algorithm module to discretize the acquired detection signal and the reference signal and store them in the corresponding array. The phase-sensitive detection algorithm and the cross-correlation algorithm are processed respectively. Then, the results of the two algorithms are processed by the root mean square algorithm to obtain the final imaging detection signal, achieving a better filtering effect. Finally, the portable computer displays the waveform in real time on the display end based on the data of the imaging detection signal.

[0073] like Figure 3 As shown, when the capacitance probe 1 is swept across the test object 2, there is a circular defect on the specimen, therefore the detection signal has a trough; as Figure 4 As shown, water seepage detection was simulated on specimens with defects of different sizes. Water was poured into the defects, and a capacitance probe 1 was used for scanning. The detection results show that as the size of the seepage defect increases, the amplitude of the detection signal decreases. Figure 5 The aging test involves using the capacitance probe 1 to test the test subject 2 at different aging times. The test results show that as the aging time increases, the capacitance value detected by the sensor decreases, indicating that the capacitance probe 1 has the ability to detect aging. The specific capacitance value corresponds to the aging time.

[0074] In the description of this invention, various embodiments of the apparatus and / or process have been illustrated using block diagrams, flowcharts, and / or examples. To the extent that such block diagrams, flowcharts, and / or examples contain one or more functions and / or operations, those skilled in the art will understand that each function and / or operation within such block diagrams, flowcharts, or examples can be implemented individually and / or collectively by a great many different hardware, software, firmware, or virtually any combination thereof.

[0075] There is little difference between the hardware and software implementations of various aspects of the system; the use of hardware or software is often (but not always, as the choice between hardware and software may become important in some situations) a design choice representing a trade-off between cost and efficiency. Various means (e.g., hardware, software, and / or firmware) by which the processes and / or systems and / or other technologies described herein can be implemented exist, and preferred means will vary depending on the context in which the processes and / or systems and / or other technologies are deployed. For example, if the implementer determines that speed and accuracy are extremely important, then the implementer may choose a primarily hardware and / or firmware approach; if flexibility is extremely important, then the implementer may choose a primarily software implementation; or, but equally alternatively, the implementer may choose a combination of hardware, software, and / or firmware.

[0076] The terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0077] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

[0078] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

Claims

1. A multifunctional portable capacitive imaging fiberglass storage tank inspection system, characterized in that, It includes a detection device and a capacitance probe; the detection device includes a signal generation module, a signal acquisition module, an impedance transformation and preprocessing module, and a host computer; the capacitance probe includes an excitation plate and a detection plate arranged on the same plane with a spacing. The signal generation module simultaneously generates an excitation signal and a reference signal. The excitation signal is transmitted to the excitation electrode plate via an electrical connection. The original detection signal generated by the detection electrode plate is amplified and filtered by the impedance transformation and preprocessing module to generate an analog detection signal. The analog detection signal and the reference signal are acquired in real time by the signal acquisition module and converted into a digital detection signal DS and a digital reference signal RS by an A / D converter. The digital detection signal DS and the digital reference signal RS are input to the host computer. The host computer calls the dual-layer filtering algorithm module to process the digital detection signal DS and the digital reference signal RS, and finally obtains the imaging detection signal VS. The impedance transformation and preprocessing module consists of a high-gain multi-channel amplification stage, an anti-power frequency filtering stage, and a noise removal stage. It can amplify the target frequency component in the signal a second time and effectively attenuate the 50Hz power frequency signal and non-target frequency components. The original detection signal is a charge signal, which is transformed into a voltage signal proportional to its charge by the impedance transformation and preprocessing module and output in the form of low output impedance. The front stage uses an LPC662 chip, which utilizes its extremely low bias current characteristics to achieve signal gain. The anti-power frequency filtering stage is used to filter out the strong 50Hz power frequency signal in the amplified signal, and works with the noise removal stage to achieve secondary amplification of the desired frequency component and effective attenuation of non-target frequency components. The dual-layer filtering algorithm module includes a phase-sensitive detection algorithm module and a cross-correlation algorithm module. The digital detection signal DS and the digital reference signal RS are respectively subjected to phase-sensitive detection operation by the phase-sensitive detection algorithm module and cross-correlation operation by the cross-correlation algorithm module. Then, the output results of the two algorithm modules are processed by the root mean square algorithm to obtain the imaging detection signal VS. The specific process of the phase-sensitive detection algorithm module includes the following steps: S1, the phase-sensitive detection algorithm module discretizes the digital reference signal RS to generate a discrete reference signal and stores it in the array [rs]; at the same time, the cross-correlation algorithm module discretizes the digital detection signal DS to generate a discrete detection signal and stores it in the array [ds]. S2, the phase-sensitive detection algorithm module generates a square wave signal SQ with a 90° phase shift based on the discrete reference signal and stores it in the input array [sq]; specifically: The array [rs] corresponding to the acquired real-time reference voltage signal is judged. If [rs]>0, then [sq]=1; if [rs]<=0, then [sq]=-1. When N>T0 / (4*t0)+1, the obtained F1 square wave signal is stored in the array [sq], thereby making the phase of [sq] advance by 90° compared to [rs]. in, ; S3, using the square wave signal SQ as a reference, perform phase-sensitive detection processing on the discrete detection signal, then perform integral filtering to obtain the first detection signal R1, and store it in the array [r1]; S4, the cross-correlation algorithm performs cross-correlation operation on the discrete reference signal and the discrete detection signal, and after integral filtering, obtains the second detection signal R2 and stores it in the array [r2]. S5, perform root mean square algorithm processing on the first detection signal R1 and the second detection signal R2 to generate the imaging detection signal VS, and store it in the array [vs]; Specifically, S3 involves: processing the detected signal DS in real time using the square wave signal corresponding to the array [sq] as a reference, and storing the result in the array [ps]. That is, if [sq] > 0, then [ps] = [ds]; if [sq] <= 0, then [ps] = -[ds]. Then, the array [ps] is subjected to integral filtering processing. The integral filtering of array [ps] is performed as follows: Let the integration interval be [T0, T1], where T0 is a certain moment after the start of sampling, T1 - T0 = ΔT, and ΔT is selected as an integer multiple of the sampling signal period. Multiply each data point in array [ps] by the sampling time interval t0 and sum them, then divide by ΔT. Store the result in array [r1]. Integrate and divide by ΔT once for each new sampled data point, and store the result sequentially in [r1]. This yields array [r1] corresponding to the first detected signal R1. In the formula: ， n satisfies .

2. The multifunctional portable capacitive imaging fiberglass storage tank inspection system according to claim 1, characterized in that, The cross-correlation operation in S4 specifically involves multiplying the corresponding data in array [rs] and array [ds] and storing the result in array [cc]. The array [cc] is also subjected to integral filtering, and the result is stored in array [r2], thereby obtaining the detection signal array [r2] after cross-correlation algorithm processing.

3. The multifunctional portable capacitive imaging fiberglass storage tank inspection system according to claim 1, characterized in that, The capacitive probe also includes a protective shell with a scanning port at the bottom. A printed circuit board is embedded in the scanning port. The excitation plate and the detection plate are symmetrically arranged on the printed circuit board. An insulating protective layer is provided on the protective shell and below the printed circuit board. The insulating protective layer can cover the scanning port.

4. The multifunctional portable capacitive imaging fiberglass storage tank inspection system according to claim 1, characterized in that, The excitation electrode and the detection electrode are configured as interdigitated electrode plates or back-to-back isosceles triangular electrode plates; the back-to-back arrangement of triangular electrode plates enables defect detection; the interdigitated electrode plates enable aging detection.

5. The multifunctional portable capacitive imaging fiberglass storage tank inspection system according to claim 3, characterized in that, Four rollers are symmetrically arranged at the bottom of the protective shell and around the scanning port.

6. The multifunctional portable capacitive imaging fiberglass storage tank inspection system according to claim 1, characterized in that, The detection device includes an expansion dock, which is integrated with the host computer. All other modules are located within the expansion dock, which is equipped with a connector capable of connecting the capacitance probe.

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