Time synchronization method and system for detector in pipeline

Abstract

The invention discloses a time synchronization method and system for a detector in a pipeline, and mainly relates to the technical field of application of the detector in the pipeline. Comprising the following steps: setting the transmitting frequency of a transmitter in a MARK box; detecting a second pulse synchronization signal sent by a satellite through the MARK box; resetting a timer in the MARK box by a rising edge of a pulse per second signal sent by the satellite, and pulling up a PWM pulse level; the timer turns over the PWM level, and PWM wave output is closed after the PWM level is turned over five times; the steps are repeated once every five seconds. The method has the beneficial effects that the time of the inner detector can be periodically synchronized, the time error accumulated due to the jitter of the crystal oscillator of the inner detector is reduced, and the accuracy of subsequent defect positioning is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of application of in-pipeline detectors, and in particular to a time synchronization method and system for in-pipeline detectors. Background Art

[0002] When the detector in the pipeline is working inside the pipe, the mileage collected by the detector may deviate greatly from the actual operating mileage due to factors such as slipping of the mileage wheel or clogging by foreign objects. The gyroscope and acceleration sensor equipment inside the detector may have accumulated errors due to sensor accuracy problems or long-term operation, and the detector operation path obtained by integration may deviate greatly from the actual operation status. When the detector detects a defect in the pipe wall, the actual defect cannot be accurately located based on the above parameters. In addition, the amount and risk of excavating and cutting pipes are large. When the defect positioning error leads to the excavation position error, the consequences are serious.

[0003] In the prior art, the method of correcting the defect position is to use a MARK box for auxiliary positioning. The MARK box has a sensor for detecting the magnetic field. A MARK box is placed every 1 kilometer on the pipeline laying path. When the detector with a magnetic yoke passes through the Mark box device below, the magnetic field signal received by the MARK box will increase significantly. The MARK box is used to find the point with the largest peak-to-peak value of the magnetic field to determine the time when the internal detector passes. The MARK will record the time when the detector passes, and the physical coordinates of the MARK are known. The detector will also record the defect data and the current equipment time at all times during operation. The data of the two are fused through the time parameter to correct the defect position.

[0004] The above correction method is the situation under ideal conditions. However, when the in-pipe detector is detecting in the pipeline, due to the electromagnetic shielding of the pipeline itself, it cannot communicate with GPS or other external devices to calibrate its own system time. It can only use a computer or GPS module for timing before the equipment enters the pipeline. However, since the crystal oscillator parameters used by each detector are different and the crystal oscillator itself has deviations, the detector will cause the time cumulative error to become larger and larger when it runs in the pipeline for a long time.

[0005] Therefore, it is necessary to propose a time synchronization method and system for in-pipeline detectors to solve the above problems. Summary of the invention

[0006] The object of the present invention is to provide a time synchronization method and system for a pipeline internal detector, which can periodically synchronize the internal detector time, reduce the time error accumulated due to the crystal oscillator jitter of the internal detector itself, and improve the accuracy of subsequent defect positioning.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In one aspect, a time synchronization method for a detector in a pipeline is provided, comprising the following steps:

[0009] S1: Set the transmitter transmission frequency in the MARK box;

[0010] S2: Detect the second pulse synchronization signal sent by the satellite through the MARK box;

[0011] S3: The rising edge of the second pulse signal sent by the satellite resets the timer in the MARK box and pulls the PWM pulse level high;

[0012] S4: The timer flips the PWM level and turns off the PWM wave output after flipping 5 times;

[0013] S5: Steps S1-S5 are repeated every 5 seconds.

[0014] Preferably, the step S1 specifically includes: a transmitter is integrated in the MARK box, and the transmission frequency of the transmitter is set to 10 Hz.

[0015] Preferably, steps S2-S3 are specifically as follows: a GPS module and a main control chip are integrated in the MARK, a timer is arranged on the main control chip, the GPS module is used to detect the second pulse synchronization signal sent by the satellite, and synchronize and correct its own system time through the second pulse synchronization signal sent by the satellite, and correct and reset the timer at the same time, the technical cycle of the timer is set to 0.05 seconds, after the rising edge of the second pulse synchronization signal sent by the satellite enters the main control chip, the interrupt function in the main control chip program resets the timer and pulls up the PWM pulse level.

[0016] Preferably, the step S4 is specifically as follows: when the timer technology is 0.05 seconds, the PWM level is flipped, and the PWM wave output is turned off after flipping 5 times. The PWM wave is transmitted by the transmitting coil after passing through the power amplifier circuit set in the main control chip.

[0017] Preferably, the operation mode of the transmitting coil includes the following steps:

[0018] S41: configure the GPS module so that the module periodically generates second synchronization pulses;

[0019] S42: Detect the rising edge of the second synchronization pulse sent by the satellite and enter the main control chip program interrupt processing function;

[0020] S43: reset and start the timer, the timer period is 0.05 seconds, and control the transmitting coil drive pin to output a high level, and exit the interrupt processing function;

[0021] S44: After the timer is full, it enters the interrupt processing function to flip the exciting coil drive area dynamic level to accumulate and generate 5 square wave signals with a cycle of 0.1 seconds, and stop the pulse output;

[0022] S45: Waiting for the arrival of the next GPS synchronization second pulse;

[0023] S46: Return to step S42 and continue to execute steps S42-S45.

[0024] Preferably, the electrical signal emitted by the transmitting coil is received by the receiving coil, and the voltage generated on both sides of the receiving coil is:

[0025]

[0026] Where I is the excitation current generated on the receiving coil, N is the number of turns of the receiving coil, n is the density of the receiving coil, μ r is the relative magnetic permeability of the receiving coil core, and μ0 is the magnetic permeability in vacuum.

[0027] In another aspect, a time synchronization system for a detector in a pipeline is provided, comprising:

[0028] The signal setting module is used to: set the transmitting frequency of the transmitter in the MARK box;

[0029] The signal detection module is used to detect the pulse-per-second synchronization signal sent by the satellite;

[0030] The signal processing module is used to reset the timer in the MARK box at the rising edge of the second pulse signal sent by the satellite, and pull up the PWM pulse level. At the same time, the timer flips the PWM level, and turns off the PWM wave output after flipping 5 times;

[0031] The signal output module is used to: output electrical signals;

[0032] The signal receiving module is used to receive electrical signals.

[0033] Compared with the prior art, the beneficial effects of the present invention are:

[0034] It can periodically synchronize the internal detector time to ensure that the system time error of the detector is within 100ms, reduce the time error accumulated by the crystal oscillator jitter of the internal detector itself, and improve the accuracy of subsequent defect positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of the method of the present invention.

[0036] Figure 2It is a flow chart of the working mode of the transmitting coil of the present invention.

[0037] Figure 3 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0039] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0040] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meanings of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0041] Example:

[0042] Extremely low frequency electromagnetic wave signals specifically refer to radio electromagnetic wave signals in the frequency range of 3Hz-30Hz. They have the characteristics of long propagation distance, stable propagation signal, and strong ability to penetrate attenuation media. They meet the requirements of marine and pipeline communications. Magnetic spiral tube coils are usually used in pipeline inspection to transmit and receive extremely low frequency electromagnetic waves through magnetic coupling.

[0043] Alternating Electromagnetic Field Theory

[0044]

[0045] According to Maxwell's equations, the electric field and the magnetic field are an inseparable whole. They stimulate each other and serve as sources for each other, forming a unified electromagnetic field. The changing electric field can stimulate the changing magnetic field with the same phase and perpendicular direction, and the changing magnetic field also produces a changing electric field. The basic principle of electromagnetic wave transmission is that energy and momentum are transmitted in the form of waves through the alternating electromagnetic field.

[0046] In the ELF communication system, the solenoid-type transmitting coil is responsible for generating ELF electromagnetic signals. This process is based on the principle of Maxwell's electromagnetic equations: when an AC power source is connected to the transmitting coil, an alternating magnetic field is generated around the coil, thereby radiating an ELF electromagnetic wave signal with the same frequency as the power source. On the other hand, the receiving coil captures these signals by electromagnetic induction. Specifically, the alternating magnetic field generates an induced electromotive force on the receiving coil. By performing algorithmic analysis on this received voltage signal, the corresponding data information can be extracted and interpreted.

[0047] According to the extremely low frequency communication principle, this embodiment provides a time synchronization method for a detector in a pipeline, such as Figure 1 As shown, the specific steps include:

[0048] S1: Set the transmitter transmission frequency in the MARK box;

[0049] S2: Detect the second pulse synchronization signal sent by the satellite through the MARK box;

[0050] S3: The rising edge of the second pulse signal sent by the satellite resets the timer in the MARK box and pulls the PWM pulse level high;

[0051] S4: The timer flips the PWM level and turns off the PWM wave output after flipping 5 times;

[0052] S5: Steps S1-S5 are repeated every 5 seconds.

[0053] The above steps are specifically as follows: a transmitter module is integrated into the MARK box, and the transmitting frequency of the transmitter is set to 10Hz, which is staggered from the frequency band of 22Hz of the conventional transmitter frequency to prevent mutual interference between signals. The MARK box system is equipped with a GPS module. During operation, it can always detect the second pulse synchronization signal sent by the satellite to synchronize and correct its own system time. At the same time, the timer of the main control chip is corrected and reset. The timer counting period is set to 0.05S. After the rising edge of the satellite second pulse arrives, the chip program interrupt function is entered to reset the timer and pull up the PWM pulse level. When the timer count reaches 0.05S, the PWM level is flipped. After flipping 5 times, the PWM wave output is turned off. The above process is repeated every 5s.

[0054] This PWM wave is precisely controlled by the internal timer and GPIO pin of the main control chip, and after the current and voltage of the signal are amplified by the power amplifier circuit, it is transmitted by the transmitting coil.

[0055] The transmitting coil works like this Figure 2 As shown, specifically including:

[0056] S41: configure the GPS module so that the module periodically generates second synchronization pulses;

[0057] S42: Detect the rising edge of the second synchronization pulse sent by the satellite and enter the main control chip program interrupt processing function;

[0058] S43: reset and start the timer, the timer period is 0.05 seconds, and control the transmitting coil drive pin to output a high level, and exit the interrupt processing function;

[0059] S44: After the timer is full, it enters the interrupt processing function to flip the exciting coil drive area dynamic level to accumulate and generate 5 square wave signals with a cycle of 0.1 seconds, and stop the pulse output;

[0060] S45: Waiting for the arrival of the next GPS synchronization second pulse;

[0061] S46: Return to step S42 and continue to execute steps S42-S45.

[0062] The receiver is integrated into the pipeline detector, and its main components include receiving coil, bandpass analog filter, operational amplifier module, voltage comparator, and FPGA chip. The receiving coil is used to receive the extremely low frequency electromagnetic signal emitted by the MARK box transmitter located on the ground. After the extremely low frequency electromagnetic signal penetrates the metal pipe wall of the oil and gas pipeline, the signal strength will be greatly attenuated, and the detection sensitivity of the extremely low frequency receiving coil is required to be high. According to the law of electromagnetic induction, the voltage generated by the two sides of the receiving coil is:

[0063]

[0064] Where I is the excitation current generated on the receiving coil, N is the number of turns of the receiving coil, n is the density of the receiving coil, μ ris the relative magnetic permeability of the receiving coil core, μ0 is the magnetic permeability in vacuum, when other conditions remain unchanged, the more turns of the receiving coil, the greater the coil inductance, the greater the induced voltage generated on both sides of the receiving coil, and the higher the overall sensitivity of the coil. A thinner wire can be selected for winding, and the number of winding turns can be increased to improve the coil detection sensitivity. The core material can be silicon steel sheet to increase the induced electromotive force. When the extremely low frequency electromagnetic signal penetrates the metal oil and gas pipe wall, it will be severely attenuated, making the voltage signal reaching the detector receiving coil very weak and mixed with a lot of external noise, affecting the time synchronization of the detector. The solution is to use an instrument amplifier to amplify the weak signal to improve the signal quality, and then filter out other signal components of 5 to 20Hz through a high-order bandpass filter, retaining only the signal related to the excitation frequency near 10Hz, and then convert the input analog signal into a digital level signal that the FPGA chip can recognize through a voltage comparator. The working logic of the FPGA chip is to use its own clock to count the interval between the rising edges of two adjacent PWM waves. When the count value meets the interval of 100ms and three consecutive groups of PWM waves When the period meets the 100ms requirement, it is considered that the clock synchronization signal from the MARK box is received, and then the system time inside the detector is corrected when the next rising edge comes. The correction method is to detect the local system time when the rising edge signal is received. If the tens digit of the ms count is less than 5, the tens digit and the ones digit of the millisecond are cleared; if the tens digit of the ms count is greater than 50, the hundreds digit count is increased by 1, and then the tens digit and the ones digit of the millisecond are cleared. For example, when the detector system time is 5:30:210 milliseconds on December 19, 2023, the MARK box synchronization signal is received. Because the tens digit count value of the millisecond is 1, which is less than 5, the tens digit count is cleared, and the corrected time is 5:30:200 milliseconds on December 19, 2023. The following explains the rationality of using 100ms as the benchmark for time synchronization. Because there is basically one MARK box per kilometer when the pipeline is laid, and calculated based on the detector speed of 3m / s, the time it takes to pass through a MARK box is about 300 to 400s. The jitter of the clock chip used in the equipment is generally around ±10PPM, and the cumulative error after running for 400s is about 1ms, which will not exceed 100ms. Therefore, it is completely reasonable to perform 100ms time synchronization every kilometer.

[0065] In addition, if Figure 3 As shown, this embodiment also provides a time synchronization system for a detector in a pipeline, comprising:

[0066] The signal setting module is used to: set the transmitting frequency of the transmitter in the MARK box;

[0067] The signal detection module is used to detect the pulse-per-second synchronization signal sent by the satellite;

[0068] The signal processing module is used to reset the timer in the MARK box at the rising edge of the second pulse signal sent by the satellite, and pull up the PWM pulse level. At the same time, the timer flips the PWM level, and turns off the PWM wave output after flipping 5 times;

[0069] The signal output module is used to: output electrical signals;

[0070] The signal receiving module is used to receive electrical signals.

Claims

1. A time synchronization method for a detector in a pipeline, characterized in that: The following steps are involved: S1: Set the transmitter transmission frequency in the MARK box; S2: Detect the second pulse synchronization signal sent by the satellite through the MARK box; S3: The rising edge of the second pulse signal sent by the satellite resets the timer in the MARK box and pulls the PWM pulse level high; S4: The timer flips the PWM level and turns off the PWM wave output after flipping 5 times; S5: Steps S1-S5 are repeated every 5 seconds.

2. A time synchronization method for a detector in a pipeline according to claim 1, characterized in that: The step S1 specifically includes: a transmitter is integrated in the MARK box, and the transmission frequency of the transmitter is set to 10 Hz.

3. A time synchronization method for a detector in a pipeline according to claim 1, characterized in that: The steps S2-S3 are specifically as follows: the MARK is integrated with a GPS module and a main control chip, and a timer is arranged on the main control chip. The GPS module is used to detect the pulse-per-second synchronization signal sent by the satellite, and synchronize and correct its own system time through the pulse-per-second synchronization signal sent by the satellite, and correct and reset the timer at the same time. The technical cycle of the timer is set to 0.05 seconds. After the rising edge of the pulse-per-second synchronization signal sent by the satellite enters the main control chip, the interrupt function in the main control chip program resets the timer and pulls up the PWM pulse level.

4. A time synchronization method for a detector in a pipeline according to claim 3, characterized in that: The step S4 is specifically as follows: when the timer technology is 0.05 seconds, the PWM level is flipped, and after flipping 5 times, the PWM wave output is turned off. The PWM wave passes through the power amplifier circuit set in the main control chip and is then transmitted by the transmitting coil.

5. A time synchronization method for a detector in a pipeline according to claim 4, characterized in that: The working method of the transmitting coil includes the following steps: S41: configure the GPS module so that the module periodically generates second synchronization pulses; S42: Detect the rising edge of the second synchronization pulse sent by the satellite and enter the main control chip program interrupt processing function; S43: reset and start the timer, the timer period is 0.05 seconds, and control the transmitting coil drive pin to output a high level, and exit the interrupt processing function; S44: After the timer is full, it enters the interrupt processing function to flip the exciting coil drive area dynamic level to accumulate and generate 5 square wave signals with a cycle of 0.1 seconds, and stop the pulse output; S45: Waiting for the arrival of the next GPS synchronization second pulse; S46: Return to step S42 and continue to execute steps S42-S45.

6. A time synchronization method for a detector in a pipeline according to claim 5, characterized in that: The electrical signal transmitted by the transmitting coil is received by the receiving coil, and the voltage generated on both sides of the receiving coil is: Where I is the excitation current generated on the receiving coil, N is the number of turns of the receiving coil, n is the density of the receiving coil, μ r is the relative magnetic permeability of the receiving coil core, and μ0 is the magnetic permeability in vacuum.

7. A time synchronization system for a detector in a pipeline, characterized in that: include: The signal setting module is used to: set the transmitting frequency of the transmitter in the MARK box; The signal detection module is used to detect the pulse-per-second synchronization signal sent by the satellite; The signal processing module is used to reset the timer in the MARK box at the rising edge of the second pulse signal sent by the satellite, and pull up the PWM pulse level. At the same time, the timer flips the PWM level, and turns off the PWM wave output after flipping 5 times; The signal output module is used to: output electrical signals; The signal receiving module is used to receive electrical signals.

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