Pipeline wall thickness monitoring system and method based on arrayed flexible ultrasonic sensor

Abstract

The application belongs to the technical field of sensors, and proposes a pipeline wall thickness monitoring system and method based on an array type flexible ultrasonic sensor, and the technical solution points are as follows: the excitation unit generates two continuous excitation signals in interval time, and the generated two continuous excitation signals are sent to the corresponding sensor when the channel switching unit controls the on-off connection of the sensor; the sensor receives the excitation signal sent by the excitation unit and generates an ultrasonic wave signal; the monitored pipeline reflects the ultrasonic wave signal, and the sensor converts the reflected ultrasonic wave signal into an electric signal; the communication control unit determines the communication mode according to the first position information of the flexible array type sensor unit arranged on the outer wall of the monitored pipeline and the reference table, and transmits the electric signal after amplification and filtering processing to the upper computer under the determined communication mode; the upper computer calculates the wall thickness information of the monitored pipeline according to the pre-stored material sound velocity information of the monitored pipeline after receiving the electric signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a pipeline wall thickness monitoring system and method based on array flexible ultrasonic sensing. BACKGROUND

[0002] Pipeline is one of the main modes of oil and gas transportation, and corrosion is an important cause of pipeline failure. In order to prevent safety accidents caused by corrosion, it is necessary to monitor the wall thickness of the pipeline to understand the corrosion condition of the pipeline, and then take appropriate protective measures in time.

[0003] The ultrasonic sensor has great advantages in pipeline wall thickness measurement due to its characteristics of not damaging the pipeline structure, easy installation, etc. However, the currently used ultrasonic sensors are rigid structures, and are in point contact or line contact with the pipeline wall, resulting in serious loss of ultrasonic energy, and even in some complex curved containers, it is difficult to arrange and measure. At the same time, the commonly used ultrasonic sensor has a low resonant frequency, which cannot measure the thin wall thickness. The pulse width and cycle of the echo signal of the ultrasonic sensor are long, which easily causes multiple echo aliasing phenomenon, limiting the lower limit of the sensor measurement range. At the same time, due to the large volume and weight of the existing ultrasonic sensor, it will cause serious burden to the pipeline, reduce the mechanical properties and safety and reliability of service, and it is difficult to realize array to form a sensor network.

[0004] In the existing research, most of them only achieve the goal of semi-flexibility, and still have the problem of low measurement accuracy. SUMMARY

[0005] The purpose of the present application is to provide a pipeline wall thickness monitoring system and method based on array flexible ultrasonic sensing, which can realize the full flexible array arrangement of ultrasonic sensors, and has higher measurement accuracy of pipeline wall thickness.

[0006] The technical scheme adopted by the present application to solve its technical problems is:

[0007] On the one hand, the present application provides a pipeline wall thickness monitoring system based on array flexible ultrasonic sensing, comprising: a flexible array sensor unit, an excitation unit, a channel switching unit, a main control unit, a signal acquisition and processing unit, a communication control unit and an upper computer.

[0008] The flexible array sensor unit is used to attach each sensor in the flexible array sensor unit to the outer wall of the pipeline to be monitored, and is used to receive the excitation signal sent by the excitation unit and generate an ultrasonic signal when the channel switching unit controls the switch-on of the sensor, and is used to receive the reflected ultrasonic signal of the pipeline to be monitored, and transmit the reflected ultrasonic signal to the signal acquisition and processing unit after converting the reflected ultrasonic signal into an electric signal.

[0009] The main control unit is configured to set the timing of the switch-on and switch-off of the sensor controlled by the channel switching unit, and to set the number of times of generating the excitation signal by the excitation unit and the interval time between two adjacent excitation signals;

[0010] The channel switching unit is configured to control the switch-on or switch-off of the sensor according to the timing of the switch-on and switch-off of the sensor.

[0011] The excitation unit is configured to generate two continuous excitation signals within the interval time, and to send the generated two continuous excitation signals to the corresponding sensor when the switch-on of the sensor.

[0012] The signal acquisition and processing unit is configured to receive the electrical signal converted from the reflected ultrasonic wave signal, and to transmit the amplified and filtered electrical signal to the communication control unit.

[0013] The communication control unit stores a contrast table of different pipe materials and theoretical wall thickness information under different outer pipe diameters, and is configured to determine the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the to-be-monitored pipeline and the contrast table, and to transmit the amplified and filtered electrical signal to the upper computer under the determined communication mode.

[0014] The upper computer pre-stores the material sound velocity information of the to-be-monitored pipeline, and is configured to calculate the wall thickness information of the to-be-monitored pipeline according to the pre-stored material sound velocity information of the to-be-monitored pipeline after receiving the electrical signal sent by the communication control unit.

[0015] As a further optimization, the flexible array sensor unit includes a piezoelectric film, a flexible integrated circuit board, a backing and a matching inductance.

[0016] The piezoelectric film is a piezoelectric film made of PVDF, and the sensor uses a crimped terminal to lead out the electrode.

[0017] The matching inductance is used to adjust the input impedance of the piezoelectric film to be in a resonant state, and is connected in parallel with the piezoelectric film through the flexible printed circuit line on the flexible integrated circuit board.

[0018] The backing is a flexible backing, and the acoustic impedance of the flexible backing and the piezoelectric film is within a specified range, which is used to absorb ultrasonic back radiation and to make the piezoelectric film stop vibrating within a specified time.

[0019] As a further optimization, the PVDF piezoelectric sensor has a structure in which, from bottom to top, a silver ink electrode, a PVDF film silver ink electrode, a polyester substrate and a crimped terminal are arranged in sequence, and the crimped terminal is provided with a backing above.

[0020] As a further optimization, the excitation unit is a sharp pulse excitation circuit, which generates an excitation signal when exciting the sensors in the flexible array sensor unit, and the generated ultrasonic signal retains the broadband characteristics of the sensors.

[0021] As a further optimization, the interval time is the length of a half period of the ultrasonic signal reflected by the pipeline to be monitored, at which time the positive and negative echoes of the ultrasonic signal reflected by the pipeline to be monitored are offset.

[0022] As a further optimization, the communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the pipeline to be monitored and the reference table, specifically including the following steps:

[0023] Obtain the center of mass position information of the flexible array sensor unit as the first position information, and obtain the communication transmission distance information in the communication transmission direction between the communication control unit and the upper computer;

[0024] Obtain the theoretical wall thickness information of the current pipeline material under the current outer pipe diameter;

[0025] Obtain the first network state within a first specified distance information range from the first position information in the communication transmission direction between the communication control unit and the upper computer, and the second network state within a first specified distance information range from the upper computer, the first specified distance information being less than the communication transmission distance information;

[0026] Obtain the shortest straight line distance from the first position information to the outer pipe diameter surface of the pipeline to be monitored;

[0027] If the straight line distance is less than the specified distance and less than the theoretical wall thickness information, and the first network state and the second network state both meet the requirements, the determined communication mode is wireless communication mode, otherwise it is wired communication mode.

[0028] As a further optimization, the first network state meets the requirements, which means:

[0029] A first analog communication control unit is arranged at a first specified distance information from the first position information in the communication transmission direction between the communication control unit and the upper computer, and a broadcast signal is sent from the communication control unit to the first analog communication control unit, if the packet loss rate is less than 5%, the first network state meets the requirements;

[0030] The second network state meets the requirements, which means:

[0031] In the communication transmission direction between the communication control unit and the host computer, a second analog communication control unit is arranged at a first specified distance from the host computer, and a broadcast signal is sent to the host computer through the second analog communication control unit, and if the packet loss rate is lower than 3%, the second network state meets the requirement.

[0032] On the other hand, the application also provides a pipeline wall thickness monitoring method based on array flexible ultrasonic sensing, applied to the pipeline wall thickness monitoring system based on array flexible ultrasonic sensing, comprising the following steps:

[0033] Each sensor in the flexible array sensor unit is attached to the outer wall of the pipeline to be monitored;

[0034] The main control unit sets the time sequence of the switch-on and switch-off of the sensor through the channel switching unit, and sets the number of times of generating the excitation signal by the excitation unit and the interval time between the adjacent two excitation signals;

[0035] The excitation unit generates two continuous excitation signals in the interval time, and the generated two continuous excitation signals are sent to the corresponding sensor when the channel switching unit controls the switch-on of the sensor;

[0036] The flexible array sensor unit receives the excitation signal sent by the excitation unit and generates an ultrasonic signal;

[0037] The pipeline to be monitored reflects the ultrasonic signal, and the reflected ultrasonic signal is converted into an electric signal by the flexible array sensor and transmitted to the signal acquisition and processing unit, and the electric signal is amplified and filtered by the signal acquisition and processing unit and then transmitted to the communication control unit;

[0038] The communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the pipeline to be monitored and the reference table, and transmits the electric signal after amplification and filtering to the host computer in the determined communication mode;

[0039] The host computer calculates the wall thickness information of the pipeline to be monitored according to the pre-stored material sound velocity information of the pipeline to be monitored after receiving the electric signal.

[0040] The application has the following beneficial effects: through the above-mentioned pipeline wall thickness monitoring system and method based on array flexible ultrasonic sensing, each sensor in the flexible array sensor unit is completely attached to the outer wall of the pipeline to be monitored, so that the flexible integration of the sensor array is realized, and in addition, due to the selection of the channel switching, excitation mode, communication mode by the main control unit and the wall thickness calculation process of the host computer, the measurement accuracy of the pipeline wall thickness can be greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A sensor structure diagram in the embodiment 1 of the present application;

[0042] Figure 2 A continuous excitation echo signal diagram in the embodiment 1 of the present application;

[0043] Figure 3 A continuous excitation echo signal amplification diagram in the embodiment 1 of the present application;

[0044] Figure 4 A continuous excitation echo signal superposition diagram in the embodiment 1 of the present application;

[0045] Figure 5 A flow chart of a pipeline wall thickness monitoring method based on array flexible ultrasonic sensing in the embodiment 2 of the present application.

[0046] Wherein, 1 represents a piezoelectric film, 2 represents a flexible integrated circuit board, 3 represents a backing, and 4 represents a matching inductor. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in connection with the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0048] Embodiment 1

[0049] The embodiment provides a pipeline wall thickness monitoring system based on array flexible ultrasonic sensing, which comprises a flexible array sensor unit, an excitation unit, a channel switching unit, a master control unit, a signal acquisition and processing unit, a communication control unit and an upper computer.

[0050] The flexible array sensor unit is used for attaching each sensor in the flexible array sensor unit to the outer wall of a pipeline to be monitored, and is used for receiving an excitation signal sent by the excitation unit and generating an ultrasonic signal when the channel switching unit controls the switch of the sensor to be turned on, and is used for receiving a reflected ultrasonic signal of the pipeline to be monitored, and transmitting the reflected ultrasonic signal to the signal acquisition and processing unit after the reflected ultrasonic signal is converted into an electric signal.

[0051] The master control unit is used for setting the time sequence of the switch of the sensor controlled by the channel switching unit to be turned on and turned off, and is used for setting the number of times of generating the excitation signal by the excitation unit and the interval time of adjacent two excitation signals.

[0052] The channel switching unit is used for controlling the switch of the sensor to be turned on or turned off according to the time sequence of the switch of the sensor to be turned on and turned off.

[0053] The excitation unit is configured to generate two continuous excitation signals within the interval time, and send the generated two continuous excitation signals to the corresponding sensor when the switch of the sensor is turned on.

[0054] The signal acquisition and processing unit is configured to receive the electrical signal converted from the reflected ultrasonic wave signal, and transmit the electrical signal after amplification and filtering processing to the communication control unit.

[0055] The communication control unit stores a contrast table of different pipe materials and theoretical wall thickness information under different outer diameters, and is configured to determine a communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the to-be-monitored pipeline and the contrast table, and transmit the electrical signal after amplification and filtering processing to the upper computer under the determined communication mode.

[0056] The upper computer pre-stores the material sound velocity information of the to-be-monitored pipeline, and is configured to calculate the wall thickness information of the to-be-monitored pipeline according to the pre-stored material sound velocity information of the to-be-monitored pipeline after receiving the electrical signal sent by the communication control unit.

[0057] In the above system, referring to Figure 1 , the flexible array sensor unit can include a piezoelectric film 1, a flexible integrated circuit board 2, a backing 3, a matching inductance 4, and a sensor arranged on the piezoelectric film 1. The piezoelectric film 1 is a piezoelectric film made of PVDF, and the sensor uses a crimped terminal lead electrode. The matching inductance 4 is used to adjust the input impedance of the piezoelectric film 1 to make it in a resonant state, and is connected in parallel with the piezoelectric film 1 through a flexible printed circuit line on the flexible integrated circuit board 2. The backing 3 is a flexible backing, and the acoustic impedance of the flexible backing and the piezoelectric film 1 is within a specified range, which is used to absorb ultrasonic back radiation and to make the piezoelectric film 1 stop vibrating within a specified time.

[0058] In application, the piezoelectric film can be LDT0-028K, which is composed of a PVDF polymer film and a screen-printed silver ink electrode, and is laminated on a polyester substrate protective layer to avoid damage and pollution of the film. The resonant frequency of the piezoelectric film can reach 15M. Since the PVDF piezoelectric film is a high polymer material and cannot be welded with an electrode, the sensor uses a crimped terminal lead electrode. The matching inductance adjusts the input impedance of the piezoelectric film to make it in a resonant state, and is connected in parallel with the piezoelectric film through a flexible printed circuit line. The flexible backing has a similar acoustic impedance to the piezoelectric film, absorbs ultrasonic back radiation, and makes the piezoelectric film stop vibrating quickly to reduce signal tailing. In addition, the flexible backing maintains the flexibility of the sensor while playing an insulating role and can absorb back clutter to optimize the performance of the sensor.

[0059] Therefore, the PVDF piezoelectric sensor, the structure of which is arranged from bottom to top as a silver ink electrode, a PVDF film silver ink electrode, a polyester substrate and a crimping terminal, the upper side of the crimping terminal is a backing, the silver ink electrode needs to be filled with a coupling agent, and the coupling agent is a medium for enhancing the acoustic transmittance between the sensor and the pipeline.

[0060] According to the frequency spectrum characteristics of the piezoelectric film, it is difficult for square wave pulses and bipolar tuning pulses to reach a high frequency requirement of more than 10M, so a sharp pulse excitation circuit is designed in the embodiment to excite the flexible ultrasonic sensor to generate ultrasonic waves to retain the wide frequency characteristics of the sensor, that is, the excitation unit is a sharp pulse excitation circuit, when the excitation signal generated by the excitation unit excites the sensor in the flexible array sensor unit, the generated ultrasonic signal retains the wide frequency characteristics of the sensor.

[0061] In the above system, each flexible piezoelectric sensor is continuously excited twice in a short time, and the reflected ultrasonic signal is the echo signal diagram, wherein the echo signal diagram of continuous excitation is shown in Figure 2 , and the enlarged view is shown in Figure 3 , and it can be seen from one of the echo signals that when the excitation interval time is exactly half the period of the echo signal, the tail of the pulse echo is exactly positive and negative, effectively shortening the period of the pulse echo, and the effect after superposition is shown in Figure 4 Therefore, the pulse width and period can be effectively reduced.

[0062] It should be noted that in the embodiment, the communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the pipeline to be monitored and the reference table, and specifically includes the following steps:

[0063] The centroid position information of the flexible array sensor unit is obtained and used as the first position information, and the communication transmission distance information in the communication transmission direction between the communication control unit and the upper computer is obtained;

[0064] The theoretical wall thickness information of the current pipeline material under the current outer pipe diameter is obtained;

[0065] The first network state in the first position information within a first specified distance information range from the communication transmission direction between the communication control unit and the host computer, and the second network state within a first specified distance information range from the host computer, the first specified distance information is less than the communication transmission distance information, here, the setting of the first specified distance information less than the communication transmission distance information is due to the fact that the communication transmission distance is generally several kilometers, at this time, if the current pipe diameter under the current pipe material, the theoretical wall thickness is relatively thick, the calculation accuracy requirement of the actual wall thickness will be relatively low, therefore, in order to improve the data transmission efficiency, at this time, wireless communication mode is generally selected, but if accurate data transmission is required, the communication mode needs to be determined finally after subsequent judgment.

[0066] The first position information is the shortest straight line distance from the outer pipe diameter surface of the pipe to be monitored.

[0067] Here, generally speaking, for the same pipe material, the theoretical wall thickness of different outer pipe diameters should meet the industry size requirement to meet the pressure requirement during transportation, therefore, for a pipe material,

[0068] The size of the straight line distance reflects the bending degree of the pipe to be monitored, the greater the bending degree, the greater the deformation amplitude of the flexible array sensor unit, at this time, a specified distance should be limited, if the straight line distance is less than the specified distance, and the straight line distance is less than the theoretical wall thickness, at this time, it indicates that the outer pipe diameter of the pipe to be monitored is large, and the theoretical wall thickness is relatively thick, at this time, even if wireless communication mode is used for data transmission, the calculation accuracy of the wall thickness can be guaranteed, if the straight line distance is too large, at this time, the bending degree of the pipe to be monitored is small, for the same pipe material, the corresponding pipe wall thickness will be relatively thin, therefore, using wired communication mode for transmission can better guarantee the calculation accuracy of the wall thickness.

[0069] Therefore, if the straight line distance is less than the specified distance and less than the theoretical wall thickness information, and the first network state and the second network state meet the requirements at the same time, the determined communication mode is wireless communication mode, otherwise it is wired communication mode.

[0070] The selection of communication mode will be comprehensively selected in combination with the positions of the flexible array sensor unit and the host computer, in many cases, even if wireless communication mode is more convenient, but in the embodiment, in order to ensure the communication transmission efficiency and avoid data delay and data loss, wireless mode is selected and determined in combination with the first position information and the theoretical pipe wall thickness information, otherwise, only wired communication mode is used for data transmission.

[0071] Since the network state near the general host computer is better than that near the pipeline to be monitored in most cases, the threshold of the packet loss rate is set to different thresholds to meet the network state requirements in the wireless communication mode after the setting of the analog communication control unit. Therefore, in the embodiment, the first network state meeting the requirements means that:

[0072] In the communication transmission direction between the communication control unit and the host computer, a first analog communication control unit is arranged at a first specified distance from the first position information, and a broadcast signal is sent to the first analog communication control unit through the communication control unit. If the packet loss rate is lower than 5%, the first network state meets the requirements.

[0073] The second network state meeting the requirements means that:

[0074] In the communication transmission direction between the communication control unit and the host computer, a second analog communication control unit is arranged at a first specified distance from the host computer, and a broadcast signal is sent to the host computer through the second analog communication control unit. If the packet loss rate is lower than 3%, the second network state meets the requirements.

[0075] Both 5% and 3% can be flexibly adjusted according to the actual working conditions around the pipeline to be monitored and the working conditions around the host computer.

[0076] Embodiment 2

[0077] Based on embodiment 1, the embodiment provides a pipeline wall thickness monitoring method based on an array type flexible ultrasonic sensor. The flowchart is shown in Figure 5 The method comprises the following steps:

[0078] S1, each sensor in the flexible array type sensor unit is attached to the outer wall of the pipeline to be monitored;

[0079] S2, the main control unit sets the channel switching unit to control the on-off timing of the sensor, and sets the number of excitation signals generated by the excitation unit and the interval time between adjacent two excitation signals;

[0080] S3, the excitation unit generates two continuous excitation signals in the interval time, and sends the generated two continuous excitation signals to the corresponding sensor when the channel switching unit controls the on-off of the sensor;

[0081] S4, the flexible array type sensor unit receives the excitation signal sent by the excitation unit and generates an ultrasonic signal;

[0082] S5, the pipeline to be monitored reflects the ultrasonic wave signal, and transmits the reflected ultrasonic wave signal converted into an electric signal by the flexible array sensor to the signal acquisition and processing unit; the electric signal is amplified and filtered by the signal acquisition and processing unit, and then transmitted to the communication control unit;

[0083] S6, the communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the pipeline to be monitored and the reference table, and transmits the electric signal after amplification and filtering to the upper computer under the determined communication mode;

[0084] S7, the upper computer calculates the wall thickness information of the pipeline to be monitored according to the pre-stored material sound velocity information of the pipeline to be monitored after receiving the electric signal.

[0085] Embodiment 3

[0086] On the basis of embodiment 1 and embodiment 2, the pipeline with a wall thickness of 7.6mm is tested in this embodiment, the flexible array sensor unit is a 2*8 array sensor, that is, 16 sensors, the longitudinal wave sound velocity of 45 steel at room temperature is known to be 5960m / s, and the calculation result of the pipeline wall thickness can be obtained according to the following formula.

[0087] d=1 / (2vt)

[0088] Wherein, d is the wall thickness, v is the material sound velocity, and t is the time interval of the echo signal.

[0089] Table 1 is the measurement result of the 16-channel sensor system on the pipeline wall thickness, and the experimental result shows that the accuracy of the system reaches 0.02mm.

[0090] Table 1

[0091]

[0092] The above is only the preferred embodiment of the present application, and is not used to limit the present application, for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A pipeline wall thickness monitoring system based on arrayed flexible ultrasonic sensing, characterized in that, The application relates to a flexible array sensor unit, an excitation unit, a channel switching unit, a master control unit, a signal acquisition and processing unit, a communication control unit and an upper computer. The flexible array sensor unit is used for adhering each sensor in the flexible array sensor unit to the outer wall of a to-be-monitored pipeline, receiving an excitation signal sent by the excitation unit and generating an ultrasonic signal when the channel switching unit controls the switch-on of the sensor, and receiving the ultrasonic signal reflected by the to-be-monitored pipeline and transmitting the electric signal converted from the reflected ultrasonic signal to the signal acquisition and processing unit. The master control unit is used for setting the time sequence of the switch-on and switch-off of the sensor controlled by the channel switching unit, and setting the number of times of generating the excitation signal by the excitation unit and the interval time of the adjacent two excitation signals. The channel switching unit is used for controlling the switch-on or switch-off of the sensor according to the time sequence of the switch-on and switch-off of the sensor. The excitation unit is used for generating the continuous two excitation signals in the interval time, and sending the generated continuous two excitation signals to the corresponding sensor when the switch-on of the sensor. The signal acquisition and processing unit is used for receiving the electric signal converted from the reflected ultrasonic signal, and transmitting the amplified and filtered electric signal to the communication control unit. The communication control unit stores a contrast table of different outer pipe diameters, different pipeline materials and theoretical wall thickness information, determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the to-be-monitored pipeline and the contrast table, and transmits the amplified and filtered electric signal to the upper computer in the determined communication mode. The upper computer prestores the material sound velocity information of the to-be-monitored pipeline, and calculates the wall thickness information of the to-be-monitored pipeline according to the prestored material sound velocity information of the to-be-monitored pipeline after receiving the electric signal sent by the communication control unit. The communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the to-be-monitored pipeline and the contrast table, and specifically comprises the following steps: The center position information of the flexible array sensor unit is obtained and taken as the first position information, and the communication transmission distance information in the communication transmission direction between the communication control unit and the upper computer is obtained. The theoretical wall thickness information of the current pipeline material under the current outer pipe diameter is obtained. The first network state in the first position information within a first specified distance information range from the outer pipe diameter surface of the to-be-monitored pipeline is obtained, and the second network state within a second specified distance information range from the upper computer is obtained, and the first specified distance information is smaller than the communication transmission distance information. The shortest straight line distance from the first position information to the outer pipe diameter surface of the to-be-monitored pipeline is obtained, and for one kind of pipeline material, the size of the straight line distance reflects the bending degree of the to-be-monitored pipeline, and the greater the bending degree is, the greater the deformation amplitude of the flexible array sensor unit is. ​ If the straight line distance is less than the specified distance and less than the theoretical wall thickness information, and the first network state and the second network state meet the requirements at the same time, the determined communication mode is a wireless communication mode, otherwise it is a wired communication mode.

2. The array-based flexible ultrasonic sensing based pipe wall thickness monitoring system as claimed in claim 1, wherein, The flexible array sensor unit includes a piezoelectric film, a flexible integrated circuit board, a backing and a matching inductor; The piezoelectric film is a piezoelectric film made of PVDF, and the sensor uses a crimped terminal lead electrode; The matching inductor is used to adjust the input impedance of the piezoelectric film to be in a resonant state, and is connected in parallel with the piezoelectric film through a flexible printed circuit on the flexible integrated circuit board; The backing is a flexible backing, and the acoustic impedance of the flexible backing and the piezoelectric film is within a specified range, which is used to absorb ultrasonic back radiation and to make the piezoelectric film stop vibrating within a specified time.

3. The array-based flexible ultrasonic sensing based pipe wall thickness monitoring system as claimed in claim 2, wherein, The piezoelectric film made of PVDF has a structure arranged from bottom to top as silver ink electrode, PVDF film silver ink electrode, polyester substrate and crimped terminal, and the crimped terminal is provided with a backing.

4. The array-based flexible ultrasonic sensing based pipe wall thickness monitoring system as claimed in claim 1, wherein, The excitation unit is a sharp pulse excitation circuit, and the excitation signal generated thereby retains the wideband characteristics of the sensor when exciting the sensor in the flexible array sensor unit.

5. The array-based flexible ultrasonic sensing based pipe wall thickness monitoring system as claimed in claim 1, wherein, The interval time is the half cycle length of the ultrasonic signal reflected by the pipeline to be monitored, at which time the pulse echo tail of the ultrasonic signal reflected by the pipeline to be monitored is positively and negatively canceled out.

6. The array-based flexible ultrasonic sensing based pipe wall thickness monitoring system as claimed in claim 1, wherein, The first network state meets the requirements, which means that: In the communication transmission direction between the communication control unit and the host computer, a first analog communication control unit is arranged at a first specified distance from the first position information, and a broadcast signal is sent to the first analog communication control unit through the communication control unit, and if the packet loss rate is less than 5%, the first network state meets the requirements; The second network state meets the requirements, which means that: In the communication transmission direction between the communication control unit and the host computer, a second analog communication control unit is arranged at a first specified distance from the host computer, and a broadcast signal is sent to the host computer through the second analog communication control unit, and if the packet loss rate is less than 3%, the second network state meets the requirements.

7. The method for pipeline wall thickness monitoring based on arrayed flexible ultrasonic sensing, applied to the pipeline wall thickness monitoring system based on arrayed flexible ultrasonic sensing according to any one of claims 1-6, characterized in that, The steps include: Each sensor in the flexible array sensor unit is attached to the outer wall of the pipeline to be monitored; The main control unit sets the channel switching unit to control the on-off timing of the sensor, and sets the number of excitation signals generated by the excitation unit and the interval time between adjacent two excitation signals; The excitation unit generates two continuous excitation signals within the interval time, and the generated two continuous excitation signals are sent to the corresponding sensor when the channel switching unit controls the on-off of the sensor; The flexible array sensor unit receives the excitation signal sent by the excitation unit and generates an ultrasonic signal; The pipeline to be monitored reflects the ultrasonic signal, and the reflected ultrasonic signal is converted into an electric signal by the flexible array sensor and transmitted to the signal acquisition and processing unit, which amplifies and filters the electric signal and then transmits it to the communication control unit; The communication control unit determines the communication mode according to the first position information of the flexible array sensor unit arranged on the outer wall of the to-be-monitored pipeline and the reference table, and transmits the electrical signal after amplification and filtering to the upper computer in the determined communication mode. The upper computer calculates the wall thickness information of the to-be-monitored pipeline according to the pre-stored material sound velocity information of the to-be-monitored pipeline after receiving the electrical signal.

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