A non-intrusive calibration system for shipboard piping pressure instrumentation based on ultrasonic measurement
By using a non-invasive calibration system based on ultrasonic measurement, the shortcomings of conventional pressure measurement technology in ship pipeline pressure measurement have been solved, achieving high-precision and safe pressure measurement while avoiding damage to the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NAVAL UNIV OF ENG PLA
- Filing Date
- 2026-04-24
- Publication Date
- 2026-06-05
AI Technical Summary
Conventional pressure measurement techniques suffer from insufficient measurement performance and adaptability in ship pipeline pressure measurement, especially in corrosive, toxic, and high-pressure environments where they are difficult to use for detection and maintenance. Furthermore, invasive measurement may damage precision hydraulic systems.
A non-invasive calibration system based on ultrasonic measurement is adopted, including a control module, a transmission drive module, an ultrasonic transmission module, an ultrasonic timing module, and an ultrasonic receiving module. Through synchronous triggering, signal conditioning, and temperature compensation, non-contact pressure measurement is achieved.
It achieves high-precision pressure measurement in complex environments, avoids damage to the system, and improves the accuracy and safety of the measurement.
Smart Images
Figure CN122149736A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ship management and monitoring technology, and particularly relates to a non-invasive calibration system for ship pipeline pressure gauges based on ultrasonic measurement. Background Technology
[0002] In the reliability and safety monitoring of marine equipment (such as oil and water pipelines and various liquid pressure vessels), pressure instruments of various types are widely used and play a crucial role. Currently, the main pressure measurement method involves directly contacting the pressure sensor with the liquid to measure the pressure within the pipeline. Commonly used pressure instrument types include Bourdon tube, strain gauge, piezoresistive, and vibrating wire types. These conventional pressure measurement technologies are accurate, stable, and suitable for many applications. However, they also have certain limitations: because they are interventional pressure measurements, they require reserved installation interfaces, which makes instrument testing and diagnosis difficult, especially when the measured liquid is corrosive, toxic, or under high pressure, posing a significant risk to instrument testing and maintenance personnel. In some special applications, conventional interventional measurements are not suitable, such as certain marine systems with complex and highly precise hydraulic systems. Frequent disassembly of the interventional pipeline pressure measurement device during maintenance may damage the performance of the original system. Summary of the Invention
[0003] The purpose of this invention is to address the shortcomings of conventional pressure measurement technology in terms of measurement performance and adaptability during ship pipeline pressure measurement, and to provide a non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement.
[0004] To achieve the above objectives, the present invention adopts the following technical solution.
[0005] A non-invasive calibration system for ship pipeline pressure gauges based on ultrasonic measurement includes a control module, a transmission drive module, an ultrasonic transmission module, an ultrasonic timing module, and an ultrasonic receiving module.
[0006] The control module includes an STM32 main control chip;
[0007] The transmitting drive module consists of an NPN transistor, a current-limiting resistor, and a coupling capacitor. It is used to amplify the trigger signal output by the control module to provide driving current for the transmitting transducer, ensuring ultrasonic transmission power and detection distance, while preventing the transducer from being damaged due to excessive current.
[0008] The ultrasonic transmitting module includes a timer chip for generating square wave pulses and a timer power supply circuit for powering the timer chip;
[0009] The ultrasonic timing module includes a TDC time-to-digital converter, a high-precision digital timing chip, and peripheral circuitry.
[0010] The ultrasonic receiving module includes an ultrasonic transducer, impedance matching and signal coupling circuit, multi-stage amplification circuit, bandpass filter circuit, and peak detection and comparison circuit.
[0011] The resonant frequency of the transducer receiver is matched with that of the transducer transmitter, and the output is an electrical signal with the same frequency as the ultrasonic wave. The electrical signal enters the impedance matching and signal coupling circuit for preprocessing, and then passes through a multi-stage amplifier circuit to amplify the signal.
[0012] The bandpass filter circuit adjusts the RC resonant circuit to make the center frequency of the bandpass filter exactly match the resonant frequency of the transducer. The passband width is adjusted according to the bandwidth of the echo signal. Through the RC resonance principle, only the target signal frequency is allowed to pass through, and all irrelevant noise is filtered out.
[0013] Finally, peak detection and comparison circuits are used to convert the filtered AC signal into a digital signal.
[0014] A further improvement or preferred embodiment of the aforementioned non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement is based on the following process for calibration:
[0015] a. Synchronous triggering of launch and timing start
[0016] The main control chip performs two core synchronous operations: First, it outputs a trigger signal to the drive circuit of the ultrasonic transmitting circuit. After the drive circuit receives the trigger signal, it amplifies the signal to provide drive current for the transmitting transducer. Second, while outputting the transmitting trigger signal, it simultaneously sends a high-level start signal to the ultrasonic timing module. The ultrasonic timing module starts its internal high-precision timing module to start precise timing and accumulate time intervals until a stop signal is received.
[0017] b. Ultrasonic wave propagation and echo reception
[0018] The ultrasonic waves emitted by the transmitting transducer propagate at a constant speed in the pipeline until they reach the ultrasonic transducer. The round-trip flight time of the ultrasonic waves (i.e., the time duration of the TDC) is proportional to the propagation distance.
[0019] c. Signal conditioning and timing stop
[0020] The echo signal from the received transducer triggers the TDC to stop timing;
[0021] d. Data Reading and Processing
[0022] The control module reads the digital flight time stored in the timer chip register through the communication protocol, and at the same time reads the ambient temperature data collected by the temperature sensor, and performs temperature compensation processing to ensure the accuracy and stability of the measurement results.
[0023] Temperature compensation processing refers to calculating the actual propagation speed of ultrasound at the current temperature based on the ambient temperature T, replacing the speed of sound under standard conditions, and offsetting the impact of temperature changes on flight time conversion; the control module calculates the ultrasonic ship time based on correlation method time measurement;
[0024] The control module converts the measured time value into the liquid pressure value in the measured pipeline based on the time-pressure conversion program;
[0025] f. Based on the parameters set by the user,
[0026] Read the corresponding calibration data, use the TDC time measurement method to measure the ultrasonic propagation time multiple times, perform median filtering on the measured time values, and also use median filtering on the RTD temperature values measured by the TDC chip to remove abnormal data. Read the pressure value data corresponding to the propagation time and temperature stored in the system calibration database, and use bilinear interpolation to convert the measured temperature and time values into the final pipeline liquid pressure value.
[0027] g. Under different pipeline pressure and parameter conditions, perform ultrasonic pressure testing on the pipeline and calibrate and adjust the pipeline liquid pressure gauges.
[0028] In a further improved or preferred embodiment of the aforementioned non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement, the timer power supply circuit is powered by an external +5V power supply. A first resistor R1 and a second resistor R2, connected to the timer's high-level trigger terminal and timer discharge terminal, charge the first capacitor C1, which is connected to the timer's GND ground terminal. A comparator built into the timer chip triggers a transition by comparing the charging state of the first capacitor C1, controlling the trigger's set signal to conduct, and the timer output terminal begins to discharge. The first capacitor C1 discharges through the second resistor R2 connected to the timer discharge terminal. The comparator triggers a transition by comparing the discharge state of the first capacitor C1, controlling the trigger's set signal to cut off, and the timer output terminal stops discharging. This process continuously generates a rectangular pulse signal. The timer chip also has a timer voltage control terminal to change the reference voltage. The voltage control terminal is grounded through a second capacitor C1 with smaller parameters to eliminate interference.
[0029] In a further improved or preferred embodiment of the aforementioned non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement, the ultrasonic receiving module includes an ultrasonic transducer, an impedance matching and signal coupling circuit, a multi-stage amplification circuit, a bandpass filter circuit, and a peak detection and comparison circuit.
[0030] An ultrasonic transducer outputs an electrical signal with the same frequency as the ultrasonic wave by using a transducer whose resonant frequency is matched to that of the ultrasonic wave generator.
[0031] At this point, the output electrical signal amplitude is weak (μV~mV level) and contains static capacitance interference from the transducer itself and a small amount of environmental noise. It cannot be processed directly and needs to be preprocessed by impedance matching and signal coupling circuits, and then amplified by multi-stage amplifier circuits.
[0032] A further improvement or preferred embodiment of the aforementioned non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement includes an impedance matching and signal coupling circuit comprising: an LC matching network resonating with the static capacitor of the transducer and a coupling capacitor; the LC matching network is used to eliminate the attenuation of the electrical signal caused by the capacitor and to match the output impedance of the transducer with the input impedance of the preamplifier circuit; the coupling capacitor is used to isolate the DC component in the output signal of the transducer, allowing only the AC signal (the electrical signal corresponding to the ultrasonic wave) to pass through, while filtering out some low-frequency noise; the current-limiting resistor limits the input current, protects the input terminal of the amplifier circuit, and prevents instantaneous signal damage to the device.
[0033] A further improvement or preferred embodiment of the aforementioned non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement includes an ultrasonic timing module comprising a TDC time-to-digital converter, a high-precision digital timing chip, and peripheral circuitry. The peripheral circuitry includes a high-speed clock crystal oscillator for providing a reference, and a power supply circuit that is connected to the analog power supply interface and the digital power supply interface respectively via two large capacitors and isolated by an isolation resistor. Attached Figure Description
[0034] Figure 1 This is a schematic diagram of the ultrasonic measurement principle for non-invasive calibration of ship pipeline pressure instruments based on ultrasonic measurement.
[0035] Figure 2 This is a flowchart of the ultrasonic receiving circuit.
[0036] Figure 3 This shows the relationship between pressure and ultrasonic wave transmission time at different temperatures. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0038] Based on the fundamental principle of non-invasive pipeline liquid pressure measurement, this application provides a non-invasive calibration method that is more suitable for pressure instruments in marine pipelines. It is mainly used to complete the on-site calibration of non-invasive pipeline liquid pressure instruments, avoiding the application limitations of traditional pressure instrument calibration and testing schemes in corresponding scenarios.
[0039] The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement in this application achieves calibration by using the pulse-echo method to accurately analyze ship pipeline pressure. The pulse-echo method, based on the direct-time method, transforms a single measurement into multiple measurements. Figure 1 As shown, the transmitting circuit emits ultrasonic waves, and the receiving circuit receives the ultrasonic waves and feeds the information back to the transmitting circuit. The transmitting circuit then emits ultrasonic waves again, and this process is repeated N times. After that, the timer stops. The total time is divided by the number of cycles to obtain the time required for a single transmission of the ultrasonic wave. This method can measure the transmission time of ultrasonic waves more accurately than the direct time method. Therefore, the basic components of the system in this application include a control module, a transmission drive module, an ultrasonic wave transmitting module, an ultrasonic wave timing module, and an ultrasonic wave receiving module.
[0040] The control module is mainly used to complete the overall control and management of the system. The main control chip is the brain of the control module and the bridge connecting the various modules of the system. It is responsible for the overall operation of the measurement system. The selection of the main control chip is particularly important for ultrasonic non-invasive pressure measuring instruments. Not only the chip's processing speed must be considered, but also the realization of the system functions.
[0041] In this embodiment, the STM32H750 is selected as the main control chip of the measurement system. The STM32H7 series has a powerful M7 core, a double-precision floating-point unit, and an operating frequency of up to 480MHz. It can run complex algorithms and is suitable as the main controller for non-intrusive pressure measurement. It can operate in a temperature range of -40℃ to +85℃ and a working voltage range of 1.6V to 3.6V.
[0042] The ultrasonic transmitting module includes a timer chip for generating square wave pulses, a timer power supply circuit for powering the timer chip, a transmitting drive circuit, and a transducer transmitter;
[0043] The power supply circuit is powered by an external +5V power supply, which charges the first capacitor C1 connected to the timer's GND ground terminal via a first resistor R1 and a second resistor R2 connected to the timer's high-level trigger terminal and timer's discharge terminal. The timer chip has a built-in comparator that triggers a transition by comparing the charging state of the first capacitor C1 to control the trigger's set signal to conduct, thus initiating the timer output's discharge. The first capacitor C1 then discharges through the second resistor R2 connected to the timer's discharge terminal. The comparator triggers a transition by comparing the discharge state of the first capacitor C1 to control the trigger's set signal to cut off, thus stopping the timer output's discharge. This process continuously generates a rectangular pulse signal. The timer chip also has a timer voltage control terminal to change the reference voltage. The voltage control terminal is grounded through a second capacitor C1 with smaller parameters to eliminate interference.
[0044] The transmitting drive circuit amplifies the ultrasonic trigger signal output from the ultrasonic transmitting module, enabling it to power the transducer transmitter and provide drive current. This ensures ultrasonic transmission power and detection range, while preventing damage to the transducer transmitter due to excessive current. It consists of an NPN transistor, a current-limiting resistor, and a coupling capacitor.
[0045] The core requirement of ultrasonic timing circuits is to accurately capture the round-trip time of flight (ToF) of ultrasonic waves from transmission to reception. Traditional designs based on microcontroller timers are limited by the counting frequency and can only achieve microsecond-level timing, which cannot meet the high-precision requirements of industrial precision measurement, high-end testing and other scenarios.
[0046] To address the aforementioned issues, this application designs an ultrasonic timing circuit based on a dedicated TDC (Time-to-Digital Converter) to construct a high-precision, high-stability ultrasonic timing function, achieving timing accuracy from picoseconds to nanoseconds, perfectly meeting the needs of pressure instrument measurement and calibration in precision pipelines within ships.
[0047] It includes a TDC time-to-digital converter, a high-precision digital timing chip, and peripheral circuitry; the peripheral circuitry includes: a high-speed clock crystal oscillator for providing a reference; and a power supply circuit that is connected to the analog power supply interface and the digital power supply interface respectively through two large capacitors and isolated by an isolation resistor.
[0048] The TDC time-to-digital converter can directly convert "time interval to digital value", eliminating the intermediate steps of microcontroller capture, counting, and calculation, fundamentally eliminating timing errors caused by intermediate steps, and greatly improving timing accuracy.
[0049] The ultrasonic waves emitted by the transducer transmitter in the ultrasonic transmitting module propagate at a uniform speed in the medium. The propagation speed of the ultrasonic waves varies due to changes in the pressure within the pipeline. When the ultrasonic waves encounter an obstacle during propagation, they are reflected, forming an echo signal. The echo signal returns along the original propagation path and can be captured by the receiving transducer. The receiving transducer converts the mechanical vibration of the echo into a weak alternating electrical signal through the piezoelectric positive effect. However, this signal contains static capacitance interference from the transducer itself and environmental noise (such as power frequency interference and wind noise), which cannot directly trigger the TDC chip to stop timing. Therefore, this application establishes an ultrasonic receiving module.
[0050] The ultrasonic receiving circuit includes a transducer receiver, impedance matching and signal coupling circuit, multi-stage amplification circuit, bandpass filter circuit, peak detection and comparison circuit, and its processing flow is as follows: Figure 2 As shown.
[0051] The transducer receiver outputs an electrical signal with the same frequency as the ultrasonic wave through a transducer structure whose resonant frequency matches that of the ultrasonic wave generator.
[0052] At this time, the amplitude of the output electrical signal is weak (μV~mV level) and contains static capacitance interference from the transducer itself and a small amount of environmental noise. It cannot be processed directly and needs to be preprocessed by impedance matching and signal coupling circuit, and then amplified by multi-stage amplifier circuit.
[0053] Impedance matching and signal coupling circuit includes: an LC matching network resonating with the transducer's static capacitor and a coupling capacitor; the LC matching network is used to eliminate the attenuation of the electrical signal caused by the capacitor and to match the output impedance of the transducer with the input impedance of the preamplifier circuit; the coupling capacitor is used to isolate the DC component in the transducer's output signal, allowing only the AC signal (the electrical signal corresponding to ultrasound) to pass through, while filtering out some low-frequency noise; the current-limiting resistor limits the input current, protects the input terminal of the amplifier circuit, and prevents transient signals from damaging the device;
[0054] The multi-stage amplifier circuit includes: a first-stage preamplifier circuit consisting of a low-noise operational amplifier and peripheral circuits, and a second-stage main amplifier consisting of a high-gain operational amplifier and adjustment circuits.
[0055] The first-stage preamplifier circuit and the second-stage main amplifier stabilize the amplification factor through a negative feedback circuit, reduce signal distortion, and improve the circuit's load-carrying capacity, thus avoiding output signal fluctuations caused by load changes.
[0056] In addition to the target AC signal, the amplified signal contains a large amount of irrelevant noise, including power frequency interference (50Hz), high-frequency noise (greater than 100kHz) and the noise of the circuit itself. The bandpass filter circuit adjusts the RC resonant circuit to make the center frequency of the bandpass filter completely consistent with the resonant frequency of the transducer. The passband width is adjusted according to the bandwidth of the echo signal. Through the RC resonance principle, only the signal of the target signal frequency is allowed to pass through, and all irrelevant noise is filtered out.
[0057] The peak detection circuit captures the peak value of the AC signal and outputs a smooth DC signal proportional to the peak value of the AC signal. The amplitude of this DC signal reflects the strength of the echo signal—the stronger the echo, the better. The comparator circuit compares the peak-detected DC signal with a preset reference voltage. When the DC signal amplitude is higher than the reference voltage, it indicates that a valid echo signal has been detected. When the DC signal amplitude is lower than the reference voltage, it indicates that there is no valid echo or the signal is noise. Finally, the peak detection and comparator circuits convert the filtered AC signal into a digital signal.
[0058] The calibration system performs calibration operations based on the following process:
[0059] a. Synchronous triggering of launch and timing start
[0060] The main control chip performs two core synchronization operations to ensure consistency between timing and transmission: First, it outputs a trigger signal to the drive circuit of the ultrasonic transmitting circuit. After the drive circuit receives the trigger signal, it amplifies the signal to provide drive current for the transmitting transducer. Second, while outputting the transmission trigger signal, it simultaneously sends a high-level start signal to the ultrasonic timing module. The ultrasonic timing module starts its internal high-precision timing module to start precise timing and accumulate time intervals until a stop signal is received.
[0061] b. Ultrasonic wave propagation and echo reception
[0062] The ultrasonic waves emitted by the transmitting transducer propagate at a constant speed in the pipeline until they reach the ultrasonic transducer. The round-trip flight time of the ultrasonic waves (i.e., the time duration of the TDC) is proportional to the propagation distance.
[0063] c. Signal conditioning and timing stop
[0064] The echo signal from the received transducer triggers the TDC to stop timing;
[0065] d. Data Reading and Processing
[0066] The control module reads the digital flight time stored in the timer chip register through the communication protocol, and at the same time reads the ambient temperature data collected by the temperature sensor, and performs temperature compensation processing to ensure the accuracy and stability of the measurement results.
[0067] Temperature compensation processing refers to calculating the actual propagation speed of ultrasound at the current temperature based on the ambient temperature T, replacing the speed of sound under standard conditions, and offsetting the impact of temperature changes on flight time conversion; the control module calculates the ultrasonic ship time based on correlation method time measurement;
[0068] The control module converts the measured time value into the liquid pressure value in the measured pipeline based on the time-pressure conversion program;
[0069] f. Based on the parameters set by the user,
[0070] Read the corresponding calibration data, use the TDC time measurement method to measure the ultrasonic propagation time multiple times, perform median filtering on the measured time values, and also use median filtering on the RTD temperature values measured by the TDC chip to remove abnormal data. Read the pressure value data corresponding to the propagation time and temperature stored in the system calibration database, and use bilinear interpolation to convert the measured temperature and time values into the final pipeline liquid pressure value.
[0071] g. Under different pipeline pressure and parameter conditions, perform ultrasonic pressure testing on the pipeline and calibrate and adjust the pipeline liquid pressure gauges on the pipeline.
[0072] In actual pressure measurement of a pipeline, the pressure is only related to the receiving time and temperature, that is... , , , , Given the pressure values corresponding to the propagation time and temperature stored in the system calibration data table, calculate the temperature. Reception time is The pressure value at that time can be obtained by interpolating twice in the temperature direction. and ;
[0073] ;
[0074] ;
[0075] Seeking and Then, by interpolating in the time direction, the result can be obtained. for
[0076] ;
[0077] The following experimental tests are used to analyze the error of the non-invasive calibration system for ship pipeline pressure gauges based on ultrasonic measurement in this application.
[0078] The experimental steps are as follows:
[0079] (1) The probe frequency is 1MHz. The pipe material is stainless steel and the medium inside the pipe is water. The temperature interval is 1℃ and the temperature range is 20℃~50℃. At the same temperature, a test point is taken every 0.5MPa to measure the relationship between pressure and ultrasonic transmission time in the pipe. The pressure test range is 0~5MPa.
[0080] (2) Select a temperature interval of 5℃, a temperature range of 20℃~50℃, take a test point every 0.5MPa at the same temperature, and a pressure test range of 0~5MPa. Test the relationship between pressure and ultrasonic transmission time in the pipeline when the pipeline material is aluminum and copper and the medium in the pipeline is water.
[0081] (3) Replace the medium in the pipeline with lubricating oil and hydraulic oil, and conduct experiments on the pipelines of the three materials respectively. The temperature interval during the experiment is 5℃, the temperature range is 20℃~50℃, and a test point is taken every 0.5MPa at the same temperature. The pressure test range is 0~5MPa.
[0082] To obtain the relationship between pressure and sound wave transmission time, stainless steel pipes filled with water were tested under different pressure conditions. The experimental equipment was placed in a constant temperature chamber for testing, and the temperature of the experimental equipment was kept constant during the test to eliminate the influence of temperature on the test. Therefore, the transmission time of ultrasound in the pipe is only related to pressure. Figure 3 The relationship between pressure and sound wave propagation time is given at temperatures of 20℃, 30℃, 40℃, and 50℃. At 20℃, the corresponding relationship is as follows: At 30℃, the corresponding relationship is as follows: At 40℃, the corresponding relationship is as follows: At 50℃, the corresponding relationship is as follows: ;
[0083] Depend on Figure 3 It can be seen that at 0 MPa, the receiving times at 20℃, 30℃, 40℃, and 50℃ are 66187 ns, 64949 ns, 64464 ns, and 63974 ns, respectively, with corresponding curve slopes of -64.41, -57.72, -72.57, and -69.13. Based on the above analysis and... Figure 3 We can conclude that: (1) When the temperature is constant, the pressure and the sound wave transmission time are linearly related. At different temperatures, the initial (0 MPa) ultrasonic wave transmission time corresponding to zero pressure is different. The higher the temperature, the shorter the initial transmission time. This is consistent with the result obtained in the previous simulation analysis that the higher the temperature, the faster the sound wave travels in water; (2) The linear relationship between ultrasonic wave transmission time and pressure is different at different temperatures. Therefore, the relationship between ultrasonic wave transmission speed and pressure can be expressed by the following formula: In the formula, Let P be the transmission time of the ultrasonic wave in the pipe. This is the proportionality coefficient between pressure and sound wave propagation time at temperature T. The propagation time of sound waves in the pipe at a pressure of 0 MPa and a temperature of T.
[0084] That is, temperature changes will cause and Changes in pipeline type will cause and Changes in the type of medium will affect and The change yields the ultrasonic pressure measurement model as follows: ;
[0085] Pressure measurements were performed based on the above formula, and the results are shown in Table 1 below. Table 1 shows that the maximum relative error of the pressure measurement is 4%, and the minimum is 1.7918%. The overall relative error is within 4%, which meets the requirements for non-contact calibration applications of ship pipeline pressure testing and pressure instruments.
[0086] Table 1 Measurement Error Analysis
[0087]
[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement, characterized in that, It includes a control module, a transmission drive module, an ultrasonic transmission module, an ultrasonic timing module, and an ultrasonic receiving module; The control module includes an STM32 main control chip; The transmitting drive module consists of an NPN transistor, a current-limiting resistor, and a coupling capacitor. It is used to amplify the trigger signal output by the control module to provide driving current for the transmitting transducer, ensuring ultrasonic transmission power and detection distance, while preventing the transducer from being damaged due to excessive current. The ultrasonic transmitting module includes a timer chip for generating square wave pulses, a timer power supply circuit for powering the timer chip, a transmitting drive circuit, and a transducer transmitter; The ultrasonic timing module includes a TDC time-to-digital converter, a high-precision digital timing chip, and peripheral circuitry. The ultrasonic receiving module includes a transducer receiver, impedance matching and signal coupling circuit, multi-stage amplification circuit, bandpass filter circuit, peak detection and comparison circuit; The resonant frequency of the transducer receiver is matched with that of the transducer transmitter, and the output is an electrical signal with the same frequency as the ultrasonic wave. The electrical signal enters the impedance matching and signal coupling circuit for preprocessing, and then passes through a multi-stage amplifier circuit to amplify the signal. The bandpass filter circuit adjusts the RC resonant circuit to make the center frequency of the bandpass filter exactly match the resonant frequency of the transducer. The passband width is adjusted according to the bandwidth of the echo signal. Through the RC resonance principle, only the target signal frequency is allowed to pass through, and all irrelevant noise is filtered out. Finally, peak detection and comparison circuits are used to convert the filtered AC signal into a digital signal.
2. The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement according to claim 1, characterized in that, The system performs calibration based on the following process: a. Synchronous triggering of launch and timing start The main control chip performs two core synchronous operations: First, it outputs a trigger signal to the drive circuit of the ultrasonic transmitting circuit. After the drive circuit receives the trigger signal, it amplifies the signal to provide drive current for the transmitting transducer. Second, while outputting the transmitting trigger signal, it simultaneously sends a high-level start signal to the ultrasonic timing module. The ultrasonic timing module starts its internal high-precision timing module to start precise timing and accumulate time intervals until a stop signal is received. b. Ultrasonic wave propagation and echo reception The ultrasonic waves emitted by the transmitting transducer propagate at a constant speed in the pipeline until they reach the ultrasonic transducer. The round-trip flight time of the ultrasonic waves (i.e., the time of the TDC) is proportional to the propagation distance. c. Signal conditioning and timing stop The echo signal from the received transducer triggers the TDC to stop timing; d. Data Reading and Processing The control module reads the digital flight time stored in the timer chip register through the communication protocol, and at the same time reads the ambient temperature data collected by the temperature sensor, and performs temperature compensation processing to ensure the accuracy and stability of the measurement results. Temperature compensation processing refers to calculating the actual propagation speed of ultrasound at the current temperature based on the ambient temperature T, replacing the speed of sound under standard conditions, and offsetting the impact of temperature changes on flight time conversion; the control module calculates the ultrasonic ship time based on correlation method time measurement; The control module converts the measured time value into the liquid pressure value in the measured pipeline based on the time-pressure conversion program; f. Based on the parameters set by the user, Read the corresponding calibration data, use the TDC time measurement method to measure the ultrasonic propagation time multiple times, perform median filtering on the measured time values, and also use median filtering on the RTD temperature values measured by the TDC chip to remove abnormal data. Read the pressure value data corresponding to the propagation time and temperature stored in the system calibration database, and use bilinear interpolation to convert the measured temperature and time values into the final pipeline liquid pressure value. g. Under different pipeline pressure and parameter conditions, perform ultrasonic pressure testing on the pipeline and calibrate and adjust the pipeline liquid pressure gauges.
3. The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement according to claim 1, characterized in that, The timer power supply circuit is powered by an external +5V power supply. A first resistor R1 and a second resistor R2, connected to the timer's high-level trigger and discharge terminals, charge the first capacitor C1, which is connected to the timer's GND ground terminal. The timer chip has a built-in comparator that compares the charging state of the first capacitor C1 to trigger a transition, controlling the trigger's set signal to conduct, and the timer output terminal begins to discharge. The first capacitor C1 discharges through the second resistor R2 connected to the timer discharge terminal. The comparator then compares the discharge state of the first capacitor C1 to trigger a transition, controlling the trigger's set signal to cut off, and the timer output terminal stops discharging. This process continuously generates a rectangular pulse signal. The timer chip also has a timer voltage control terminal to change the reference voltage. The voltage control terminal is grounded through a second capacitor C1 with smaller parameters to eliminate interference.
4. The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement according to claim 1, characterized in that, The ultrasonic receiving module includes an ultrasonic transducer, an impedance matching and signal coupling circuit, a multi-stage amplification circuit, a bandpass filter circuit, and a peak detection and comparison circuit. An ultrasonic transducer outputs an electrical signal with the same frequency as the ultrasonic wave by using a transducer whose resonant frequency is matched to that of the ultrasonic wave generator. At this point, the output electrical signal amplitude is weak (μV~mV level) and contains static capacitance interference from the transducer itself and a small amount of environmental noise. It cannot be processed directly and needs to be preprocessed by impedance matching and signal coupling circuits, and then amplified by multi-stage amplifier circuits.
5. The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement according to claim 4, characterized in that, The impedance matching and signal coupling circuit includes: an LC matching network that resonates with the static capacitor of the transducer and a coupling capacitor; the LC matching network is used to eliminate the attenuation of the electrical signal caused by the capacitor and to match the output impedance of the transducer with the input impedance of the preamplifier circuit; the coupling capacitor is used to isolate the DC component in the output signal of the transducer, allowing only the AC signal (the electrical signal corresponding to ultrasound) to pass through, while filtering out some low-frequency noise; the current-limiting resistor limits the input current, protects the input terminal of the amplifier circuit, and avoids damage to the device by transient signals.
6. The non-invasive calibration system for ship pipeline pressure instruments based on ultrasonic measurement according to claim 1, characterized in that, The ultrasonic timing module includes a TDC time-to-digital converter, a high-precision digital timing chip, and peripheral circuitry. The peripheral circuitry includes a high-speed clock crystal oscillator for providing a reference, and a power supply circuit that is connected to the analog power supply interface and the digital power supply interface respectively through two large capacitors and isolated by an isolation resistor.