High-precision bridge deflection measurement radar system and method
By adding a transmitting final-stage coupler, a receiving-end switch, and a delay circuit to the bridge deflection radar system, and by adopting a multi-link dynamic drift correction method, the problems of insufficient measurement accuracy and data discontinuity in the existing technology have been solved, realizing high-precision and low-cost real-time monitoring of bridge deflection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-10
- Publication Date
- 2026-04-17
AI Technical Summary
Existing bridge deflection radar measurement systems suffer from problems such as insufficient dynamic drift tracking, easy loss of correction signals, discontinuous measurement data, and high hardware costs, making it impossible to achieve high-precision, long-term real-time monitoring.
The radar system is equipped with a transmitter-end coupler, a receiver-end switch, and a delay circuit. Multi-link dynamic drift correction is performed through the data processing subsystem. Combined with the periodic working mode, the correction signal can be effectively extracted and continuously monitored.
It achieves sub-millimeter level accuracy in bridge deflection measurement, ensures continuous 24-hour monitoring data, reduces hardware costs and integration difficulty, and is adaptable to different radar carrier frequencies and displacement measurement scenarios.
Smart Images
Figure CN121878682A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of bridge health monitoring and high-frequency radar measurement technology, specifically relating to a high-precision bridge deflection measurement radar system and method with phase dynamic correction function, which is applicable to real-time high-frequency monitoring of static and dynamic deflection of various types of bridges such as long-span highway bridges, railway bridges, and pedestrian overpasses. Background Technology
[0002] In radar phase-based measurement fields (such as bridge deflection and structural vibration displacement measurement), phase is the core basis for realizing the conversion of physical quantities, and "multi-link phase drift" is the primary factor causing measurement errors.
[0003] A typical architecture of an existing radar measurement system consists of a local oscillator, a transmit link (filter, power amplifier PA), a transmit antenna, a target, a receive antenna, a receive link (low-noise amplifier LNA, mixer), and a data processing unit. Its phase measurement logic is as follows: the transmit link generates a linear frequency modulated (CFM) signal (Chirp signal), which is amplified by the power amplifier and radiated to the target. The signal phase includes the inherent phase of the local oscillator, the fixed phase of the transmit link, and the drift phase due to time variations. The receive link receives the target echo, mixes it with the local oscillator signal via the mixer, and outputs the intermediate frequency (IF) phase. The data processing unit directly calculates physical quantities based on the IF signal, without considering the ΔF phase of the transmit link. f TX ( t ), receive link ∆ f RX ( t Correction is performed on drift components such as )
[0004] Current radar technology lacks a dedicated correction mechanism for phase drift, relying primarily on low-temperature drift device selection (e.g., using OCXO temperature-controlled crystal oscillators) and single-cycle power-on calibration. This approach has several drawbacks: First, drift components are not separated, conflating fixed phase delay (e.g., transmission line length) with dynamic drift (e.g., power amplifier heating). Single-cycle calibration cannot cover time-varying errors; phase drift can accumulate to approximately 30° within 10 minutes of power-on, corresponding to deflection errors of several millimeters. Second, correction signals are lost out of band. Some solutions attempt to extract correction signals by adding a coupling port at the transmitter, but because the path delay of the coupling signal is much shorter than the echo signal delay, the intermediate frequency after mixing exceeds the receiver's filter bandwidth, resulting in the correction signal being filtered out and unusable for drift extraction. Third, coordination with the measurement process is poor. The correction process is separated from the signal transmission, echo reception, and phase calculation processes, requiring a pause in normal monitoring for correction, leading to discontinuous measurement data and failing to meet the requirements for long-term real-time monitoring of bridges.
[0005] In addition, existing technologies have drawbacks such as lack of dynamic drift tracking capability, increased hardware costs, and interruption of measurement continuity. They cannot track dynamic phase drift of multiple links in real time, the long-term monitoring accuracy decreases, and calibration requires dedicated external equipment, which is prone to errors. At the same time, the calibration process leads to the loss of dynamic data. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of existing bridge deflection measurement radar systems, such as insufficient dynamic drift tracking, easy loss of correction signals, discontinuous measurement data, and high hardware costs. This invention provides a high-precision bridge deflection measurement radar system and method that, by reusing the original core modules, achieves effective extraction of correction signals and integrated correction of multi-link dynamic drift, ensuring sub-millimeter-level measurement accuracy, while guaranteeing the continuity of monitoring data, meeting the needs of long-term real-time bridge monitoring, and significantly reducing hardware costs and integration difficulty.
[0007] To achieve the above objectives, the present invention adopts the following technical solution: A high-precision bridge deflection measurement radar system includes a radar transmitting subsystem, a radar receiving subsystem, and a data processing subsystem. The radar transmitting subsystem includes a local oscillator, a chirp signal generator, a power amplifier, a transmitting antenna, and a transmitting final-stage coupler. The radar receiving subsystem includes a delay circuit, a receiving antenna, a receiving switch, a low-noise amplifier, a mixer, an intermediate frequency filter, and an analog-to-digital converter. The data processing subsystem includes an FFT unit, a phase drift correction unit, a phase unwinding unit, and a deflection calculation unit. The radar transmitting subsystem outputs a delayed coupled signal to the radar receiving subsystem, and... The transmitting antenna transmits signals. The radar receiving subsystem switches the receiver switch according to the switching command and outputs intermediate frequency raw data and correction data to the data processing subsystem. The data processing subsystem receives the raw data and correction data output by the radar receiving subsystem, and extracts the total drift of the transmission, reception and local oscillator links based on these data. It uses the correction data to dynamically correct the raw data to obtain the true phase of the target. Combined with the radar wavelength and the geometric relationship of the application scenario (such as the distance and angle between the radar and the measurement point), the true phase is converted into a deflection value or displacement value. At the same time, it generates a "transmission synchronization command" and a "switch switching command".
[0008] The local oscillator, chirp signal generator, and power amplifier are connected in sequence. One output of the power amplifier is connected to the input of the transmitting antenna, and the other output is connected to the input of the transmitting final stage coupler. The output of the transmitting final stage coupler is connected to the input of the delay circuit. The chirp signal generator generates a linear frequency modulated signal based on the local oscillator signal. After frequency multiplication, filtering, and amplification, it is output in two paths: one path is radiated to the target detection area via the transmitting antenna, and the other path is transmitted to the delay circuit via the transmitting final stage coupler. The output of the delay circuit is connected to the first input of the receiver switch to compensate for the path delay difference between the coupled signal and the echo signal. The second input of the receiver switch is connected to the receiving antenna, and the output of the receiver switch is connected to the input of the low-noise amplifier. The output of the low-noise amplifier is connected to the first input of the mixer. The output of the local oscillator is also connected to the second input of the mixer. The output of the mixer is connected to the input of the intermediate frequency filter, and the output of the intermediate frequency filter is connected to... The analog-to-digital converter (ADC) input is connected to the input of the FFT unit and the phase drift correction unit, respectively. The FFT unit output is connected to the input of the phase unwinding unit, the phase unwinding unit output is connected to the input of the phase drift correction unit, and the phase drift correction unit output is connected to the input of the deflection calculation unit. The phase drift correction unit extracts the total multi-link drift based on the original data and the corrected data, and dynamically corrects the original data to obtain the true phase of the target. The deflection calculation unit converts the true phase of the target into a deflection value by combining the radar wavelength and geometric relationship. The control signal output of the deflection calculation unit is connected to the control signal input of the receiver switch, which is used to output a switching command to the receiver switch. After receiving the switching command, the receiver switch selectively conducts the receiving antenna or the delay circuit to realize the target echo reception and the coupled signal reception, respectively. After signal processing, the original data or the corrected data is output to the data processing subsystem.
[0009] As a further description of the above technical solution: the transmitting final stage coupler is a directional coupler, preferably a directional coupler with a coupling degree of 20 dB and an isolation degree of ≥30 dB.
[0010] As a further description of the above technical solution: the receiving end switch is a 1-to-2 SPDT switch with a switching time in the nanosecond range.
[0011] This invention also provides a high-precision bridge deflection measurement method, which utilizes the aforementioned radar system and employs a periodic working mode of "multiple normal monitoring + one calibration," specifically including the following steps: (1) Power-on initialization: Start the local oscillator and Chirp signal generator, turn on the receiver by default to turn on the delay circuit, collect the initial correction phase and store the fixed phase of the transmit and receive link; (2) Normal monitoring cycle: The receiving end switches on the receiving antenna and transmits multiple linear frequency modulation signals at a fixed period, continuously collecting and temporarily storing multiple sets of intermediate frequency echo phases of the target; (3) Correction mode: Switch the receiver switch to turn on the delay circuit, transmit a linear frequency modulation signal, collect the intermediate frequency correction phase, and calculate the total dynamic drift of the multi-link; (4) Phase correction and result output: The intermediate frequency correction phase is used to dynamically correct the temporarily stored intermediate frequency echo phase and extract the true phase of the target; the true phase of the target is converted into deflection value and output by combining the geometric relationship between the radar and the measuring point; (5) Repeat steps (2) to (4) to achieve periodic continuous monitoring.
[0012] As a further description of the above technical solution: the target true phase mentioned in step (4) is obtained by subtracting the correction phase of the correction mode from the echo phase of the normal monitoring mode. i One correction mode is triggered after each normal monitoring cycle to compensate for all link drift and fixed phase, expressed as:
[0013] in, This refers to the intermediate frequency echo phase from multiple monitoring sessions under normal monitoring mode, including the target's true phase. Transmit link fixed phase Launch dynamic drift Receive dynamic drift and local oscillator phase fluctuation The expression is: ; The intermediate frequency (IF) correction phase in the correction mode does not include the target's true phase, but only the fixed phase of the transmit link, transmit dynamic drift, receive dynamic drift, and local oscillator phase fluctuation. The expression is: .
[0014] As a further description of the above technical solution: the deflection value in step (4) is calculated based on the principle of radar interferometry, which is satisfied by the change in the true phase of the target and the deflection, combined with geometric relationships. The calculation formula is as follows: , Sorted as: , in The actual phase change of the target. l For radar wavelength, i The angle between the radar line of sight and the vertical direction. , hThe vertical height between the radar and the measuring point. R This represents the radial distance between the radar and the measuring point.
[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention adds a final-stage coupler to the radar transmitting subsystem, a receiver switch and delay circuit to the receiving subsystem, and a phase drift correction unit to the data processing subsystem. It also clarifies the precise connection relationships and collaborative working logic of each component. By using delay circuits to compensate for the path delay difference between the coupled signal and the echo signal, and combining direct calculation of the echo phase and the corrected phase, it achieves integrated cancellation of the transmitted fixed phase, multi-link dynamic drift, and local oscillator phase fluctuations. This not only ensures that the corrected phase accuracy meets the requirements for sub-millimeter-level bridge deflection measurement and effectively solves the problems of insufficient dynamic drift tracking and error accumulation in existing technologies, but also significantly reduces hardware costs and integration difficulty by adding only three types of low-cost components and reusing existing core modules, thus significantly shortening the adaptation cycle. Furthermore, by adopting a periodic working mode of "multiple normal monitoring + one correction," the correction process only occupies a single frequency tuning time, ensuring continuous and uninterrupted 24-hour measurement data. Moreover, the correction method is not bound to specific frequency bands or geometric parameters, making it adaptable to different radar carrier frequencies and various displacement measurement scenarios, demonstrating strong versatility and practicality. Attached Figure Description
[0016] Figure 1 This is a diagram of the system architecture of the present invention.
[0017] Figure 2 This is a flowchart of the method of the present invention. Detailed Implementation
[0018] The claims of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of protection of the claims of the present invention shall still be within the scope of protection of the claims of the present invention. Example
[0019] This embodiment provides a high-precision bridge deflection measurement radar system. Based on the existing radar architecture, three types of devices are added: a transmitting final-stage directional coupler (coupling degree of 20 dB, isolation degree ≥30 dB), a 1-to-2 SPDT switch (switching time in the nanosecond range), and a delay circuit. The transmitting final-stage directional coupler is connected to the output of the power amplifier (PA). The two inputs of the SPDT switch are connected to the receiving antenna and the output of the delay circuit, respectively. The output of the SPDT switch is connected to the input of the low-noise amplifier (LNA). The delay circuit is connected between the transmitting final-stage directional coupler and the SPDT switch to compensate for the path delay difference between the coupled signal and the echo signal, ensuring that the intermediate frequency after mixing falls within the existing intermediate frequency filter band.
[0020] The specific structural components are as follows: Figure 1 As shown, the system includes a radar transmitting subsystem, a radar receiving subsystem, and a data processing subsystem. The radar transmitting subsystem outputs a delayed coupled signal and a transmitted signal to the transmitting antenna to the radar receiving subsystem. The radar receiving subsystem switches the receiver switch according to the switching command and outputs intermediate frequency raw data and correction data to the data processing subsystem. The data processing subsystem receives the raw data and correction data output by the radar receiving subsystem, and extracts the total drift of the transmitting, receiving, and local oscillator links based on these data. It uses the correction data to dynamically correct the raw data to obtain the true phase of the target. Combining the radar wavelength and the geometric relationship of the application scenario (such as the distance and angle between the radar and the measurement point), it converts the true phase into a deflection value or displacement value, and generates a "transmission synchronization command" and a "switch switching command".
[0021] The radar transmitting subsystem includes a local oscillator (LO), a chirp signal generator, a power amplifier (PA), a transmitting antenna (Tx Ant), and a transmitting final-stage directional coupler. The local oscillator, chirp signal generator, and power amplifier are connected in sequence. One output terminal of the power amplifier is connected to the input terminal of the transmitting antenna, and the other output terminal is connected to the input terminal of the transmitting final-stage directional coupler. The output terminal of the transmitting final-stage directional coupler is connected to the input terminal of the delay circuit. The local oscillator is used to output a reference signal with a stable frequency. The Chirp signal generator generates a low-frequency linear frequency modulated signal (bandwidth 600 MHz, period 1 ms) based on the local oscillator signal. The frequency is boosted to the target high-frequency band through the built-in frequency multiplier unit. The frequency-multiplied signal enters the filter of the transmission link to filter out noise and harmonics. The filtered clean signal is input to the power amplifier (PA) for power amplification. The amplified signal is output in two paths: one path is radiated to the target detection area through the transmitting antenna, and the other path is transmitted to the delay circuit through the final stage coupler of the transmission.
[0022] The radar receiving subsystem includes a delay circuit, a receiving antenna, an SPDT switch, a low-noise amplifier, a mixer, an intermediate frequency filter, and an analog-to-digital converter (ADC). The delay circuit is used to compensate for the path delay difference between the coupled signal and the echo signal. The output of the delay circuit is connected to the first input of the SPDT switch, the second input of the SPDT switch is connected to the receiving antenna, the output of the SPDT switch is connected to the input of the low-noise amplifier, the output of the low-noise amplifier is connected to the first input of the mixer, the output of the mixer is connected to the input of the intermediate frequency filter, and the output of the intermediate frequency filter is connected to the input of the ADC. The local oscillator is also directly connected to the mixer to provide a reference signal for mixing. The SPDT switch receives a switching command from the data processing subsystem and selectively turns on the receiving antenna or the delay circuit to receive the target echo signal and the coupled signal, respectively. The received signal is amplified by the low-noise amplifier and then input to the mixer. After mixing with the local oscillator reference signal, it is filtered by the intermediate frequency filter and sampled by the ADC, and the original data or corrected data is output to the data processing subsystem.
[0023] The data processing subsystem includes an FFT unit, a phase drift correction unit, a phase unwinding unit, and a deflection calculation unit. The phase drift correction unit extracts the total drift of multiple links based on the original data and correction data, and dynamically corrects the original data to obtain the true target phase. The deflection calculation unit converts the true target phase into a deflection value based on the radar wavelength and geometric relationships. The analog-to-digital converter (ADC) output is connected to the inputs of the FFT unit and the phase drift correction unit, respectively. The FFT unit output is connected to the input of the phase unwinding unit, the phase unwinding unit output is connected to the input of the phase drift correction unit, and the phase drift correction unit output is connected to the input of the deflection calculation unit. The data processing subsystem receives the original data and correction data output from the ADC. The phase drift correction unit extracts the total drift of the transmit, receive, and local oscillator links based on this data, and dynamically corrects the original data using the correction data to obtain the true target phase. The physical quantity conversion module of the deflection calculation unit combines the radar wavelength and the geometric relationships of the application scenario (including the vertical height between the radar and the measurement point). h Radial distance between radar and measuring point R ,satisfy , i (The angle between the radar line of sight and the vertical direction) converts the true phase into deflection or displacement values.
[0024] The control signal output terminal of the deflection calculation unit is connected to the control signal input terminal of the SPDT switch, and is used to output a "transmission synchronization command" (controlling 10 frequency modulation cycles) or a "switch switching command" (controlling the triggering of the 11th correction mode) to the SPDT switch. After receiving the switching command, the switch operates in two modes: Normal monitoring mode (frequency modulation 1-10): The SPDT switch turns on the receiving antenna to receive the target echo. After amplification by LNA, mixing by mixer, filtering by intermediate frequency filter, and sampling by ADC, the raw radar data is output to the data processing subsystem to obtain the raw phase. Correction mode (11th frequency modulation): The SPDT switch conduction delay circuit receives the coupled signal, which is amplified by LNA, mixed by mixer, filtered by intermediate frequency filter, and sampled by ADC. The correction data is then output to the data processing subsystem to obtain the correction phase. Example
[0025] This embodiment provides a high-precision bridge deflection measurement method. Utilizing the radar system from Embodiment 1, it employs a periodic working mode of "multiple normal monitoring + one calibration," and the process is as follows: Figure 2 As shown, the specific steps include: (1) Power-on initialization: After power-on, the local oscillator and chirp signal generator start up, the SPDT switch turns on the delay circuit by default, the system enters the calibration mode, and the initial calibration phase is acquired. And store the fixed phase of the transmit and receive links. ; (2) Normal monitoring cycle: After initialization, the data processing subsystem sends a "switch switching command", the SPDT switch turns on the receiving antenna, and the system enters the normal monitoring mode, transmitting a Chirp signal (linear frequency modulation signal) every 1 ms, for a total of 10 consecutive transmissions (i.e., i =10), simultaneously acquiring 10 sets of target intermediate frequency echo data, which are then sampled by the ADC and transmitted to the data processing subsystem to calculate 10 sets of intermediate frequency echo phases. ~ ; (3) Correction mode: After 10 normal monitoring cycles are completed, the data processing subsystem sends a "switch switching command" again, the SPDT switch turns on the delay circuit, the system enters the correction mode, transmits a Chirp signal, collects intermediate frequency correction data, and calculates the intermediate frequency correction phase. And based on this phase, calculate the current total dynamic drift of the multi-link; (4) Phase correction and result output: The phase drift correction unit of the data processing subsystem uses the target true phase formula ( i =1~10) Dynamically correct 10 sets of echo phases to obtain 10 sets of true target phases. ~ Using the true phase of the first group of targets as a baseline, calculate the change in the true phase of the targets in subsequent groups (groups 2 to 10): ( i =2~10); combined with radar wavelength l(Calculated based on radar carrier frequency) Vertical height between radar and measurement point h Radial distance between radar and measuring point R (Acquired via radar ranging function), utilizing and the formula for calculating deflection value The target's true phase change is converted into the corresponding deflection value (10 sets in total, with the first set having a deflection value of 0), and then output to the display terminal. (5) After completing one cycle of “10 normal monitoring + 1 correction”, repeat steps (2) to (4) to achieve 24-hour real-time high-frequency monitoring of bridge deflection.
[0026] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the present invention.
Claims
1. A high-precision bridge deflection measurement radar system, comprising a radar transmitting subsystem, a radar receiving subsystem, and a data processing subsystem; Its features are: The radar transmitting subsystem includes a local oscillator, a Chirp signal generator, a power amplifier, a transmitting antenna, and a transmitting final stage coupler; the radar receiving subsystem includes a delay circuit, a receiving antenna, a receiving end switch, a low-noise amplifier, a mixer, an intermediate frequency filter, and an analog-to-digital converter; the data processing subsystem includes an FFT unit, a phase drift correction unit, a phase unwinding unit, and a deflection calculation unit. The local oscillator, chirp signal generator, and power amplifier are connected in sequence. One output terminal of the power amplifier is connected to the input terminal of the transmitting antenna, and the other output terminal is connected to the input terminal of the transmitting final stage coupler. The output terminal of the transmitting final stage coupler is connected to the input terminal of the delay circuit. The output terminal of the delay circuit is connected to the first input terminal of the receiver switch. The second input terminal of the receiver switch is connected to the receiving antenna. The output terminal of the receiver switch is connected to the input terminal of the low-noise amplifier. The output terminal of the low-noise amplifier is connected to the first input terminal of the mixer. The output terminal of the local oscillator is also connected to the second input terminal of the mixer. The output terminal of the mixer is connected to the input terminal of the intermediate frequency filter. The output terminal of the intermediate frequency filter is connected to the input terminal of the analog-to-digital converter. The output of the analog-to-digital converter is connected to the input of the FFT unit and the input of the phase drift correction unit, respectively. The output of the FFT unit is connected to the input of the phase unwinding unit, the output of the phase unwinding unit is connected to the input of the phase drift correction unit, and the output of the phase drift correction unit is connected to the input of the deflection calculation unit. The control signal output of the deflection calculation unit is connected to the control signal input of the receiver switch, and is used to output switching commands to the receiver switch.
2. The high-precision bridge deflection measurement radar system according to claim 1, characterized in that: The final stage coupler for transmission is a directional coupler.
3. The high-precision bridge deflection measurement radar system according to claim 2, characterized in that: The directional coupler has a coupling degree of 20 dB and an isolation degree of ≥30 dB.
4. The high-precision bridge deflection measurement radar system according to claim 1, characterized in that: The receiver switch is a 1-to-2 SPDT switch with a switching time in the nanosecond range.
5. A high-precision method for measuring bridge deflection, characterized in that, The radar system according to claim 1 includes the following steps: (1) Power-on initialization: Start the local oscillator and Chirp signal generator, turn on the receiver by default to turn on the delay circuit, collect the initial correction phase and store the fixed phase of the transmit and receive link; (2) Normal monitoring cycle: The receiving antenna is turned on by the receiver switch, the linear frequency modulation signal is used, and multiple sets of intermediate frequency echo phases of the target are continuously collected and temporarily stored; (3) Correction mode: Switch the receiver switch to turn on the delay circuit, transmit a linear frequency modulation signal, collect the intermediate frequency correction phase, and calculate the total dynamic drift of the multi-link; (4) Phase correction and result output: The intermediate frequency correction phase is used to dynamically correct the temporarily stored intermediate frequency echo phase and extract the true phase of the target; the true phase of the target is converted into deflection value and output by combining the geometric relationship between the radar and the measuring point; (5) Repeat steps (2) to (4) to achieve periodic continuous monitoring.
6. The high-precision bridge deflection measurement method according to claim 5, characterized in that: The expression for the true phase of the target mentioned in step (4) is: ； in, This refers to the phase of the intermediate frequency echo; This is for intermediate frequency phase correction.
7. The high-precision bridge deflection measurement method according to claim 6, characterized in that: The formula for calculating the deflection value in step (4) is: ； in The actual phase change of the target. λ For radar wavelength, θ The angle between the radar line of sight and the vertical direction. , h The vertical height between the radar and the measuring point. R This represents the radial distance between the radar and the measuring point.