Bridge frequency indirect measurement method and system based on mobile measurement device

Abstract

The present application relates to a kind of bridge frequency indirect measurement method and system based on mobile measuring device, belong to bridge engineering measurement field, first estimate the theoretical frequency of bridge to be measured, according to theoretical frequency and preset vehicle frequency ratio back calculation device frequency and calculate air spring total stiffness, adjust air spring total stiffness to the calculated value after device is placed on the bridge to be measured and travels, wireless dynamic acceleration test analysis subsystem is respectively carried out variation modal decomposition to acceleration signal collected by each magneto-vibration sensor, then the multiple components obtained are respectively subjected to fast fourier transform to obtain frequency spectrum, determine bridge vibration component frequency spectrum after extracting bridge frequency, the average value of bridge frequency extracted from the bridge vibration component frequency spectrum of each sensor signal is obtained Bridge frequency indirect measurement result.The present application does not need to close traffic and lay out complex sensor, detection precision and efficiency are higher, and can be targeted to bridge detection by changing device itself parameter.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering measurement technology, specifically relating to a method and system for indirect measurement of bridge frequency based on a mobile measuring device. Background Technology

[0002] Bridges are critical nodes in transportation infrastructure, and their performance inevitably deteriorates with age. Accurately assessing the service status of bridge structures is a key challenge and a major technical hurdle for bridge maintenance departments, ensuring their safe operation. Bridge inspection is an effective technique for evaluating bridge service status, and frequency, a key dynamic performance indicator of bridge structures, is widely used for early warning, damage identification, and condition assessment. Given the large number and wide distribution of bridge structures, quickly detecting their frequency is a pressing technical problem that needs to be solved.

[0003] Traditional detection methods require traffic flow closure and the deployment of numerous sensors on the bridge. This method is time-consuming and costly to measure bridge frequencies, making it unsuitable for rapid testing. In summary, traditional frequency calculation methods suffer from slow detection speed and low accuracy.

[0004] Currently, my country has over one million highway bridges and tens of thousands of urban bridges. Faced with the demand for large-scale bridge safety inspections, the shortcomings of traditional bridge frequency measurement methods are becoming increasingly apparent, and they can no longer adequately meet the needs of ensuring bridge structural safety. Therefore, there is an urgent need to provide a bridge frequency measurement method that is fast and accurate.

[0005] The invention patent with publication number CN112362272A provides a measuring vehicle system for enhanced identification of bridge frequency signals. This system indirectly obtains bridge frequency signals through its design. However, this measuring vehicle system uses a combination of a tractor and a measuring vehicle; the measuring vehicle cannot move independently, and its parameters are fixed and cannot be adjusted, making it impossible to perform targeted measurements on bridges under different working conditions.

[0006] Patent CN116842775A discloses a method for identifying bridge modal vibration modes by vehicle drive, which eliminates the influence of road surface roughness. Patent CN116481747A discloses a method for identifying bridge modal vibration modes by vehicle drive, which considers the influence of bridge damping. Both methods establish two measuring vehicle-bridge models and construct bridge modal vibration modes using the vertical contact response of the measuring vehicle-bridge. However, these methods employ a system of two measuring vehicles, one moving and one stationary, with each vehicle positioned on the bridge for measurement. This system cannot perform measurements while the vehicle is in motion and still suffers from fixed and unadjustable parameters, making it unsuitable for effective measurements on different types of bridges. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method and system for indirect bridge frequency measurement based on a mobile measuring device, enabling rapid and accurate detection of bridge frequencies.

[0008] The technical solution adopted in this invention is as follows:

[0009] A method for indirect measurement of bridge frequency based on a mobile measuring device, the mobile measuring device comprising:

[0010] One wirelessly controlled mobile inspection vehicle;

[0011] Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to pick up acceleration time history response signals during the measurement process;

[0012] Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle.

[0013] One wireless dynamic acceleration test and analysis subsystem is used to receive acceleration signals collected by various magnetoelectric vibration sensors and to process and analyze the acceleration signals.

[0014] The indirect bridge frequency measurement method includes the following steps:

[0015] Step 1: Simulate the bridge under test using the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge under test.

[0016] Step 2: Calculate the frequency of the moving measuring device based on the ratio of the theoretical frequency of the bridge to be tested to the preset vehicle-bridge frequency. Convert the frequency of the moving measuring device into angular frequency and calculate the corresponding total stiffness k of the air spring suspension of the moving measuring device. v The calculation formula is as follows:

[0017]

[0018] in, ω is the angular frequency of the moving measuring device, m v For the suspension quality of the wirelessly remote-controlled mobile inspection vehicle, m w For tire mass, k w For tire stiffness;

[0019] Step 3: Adjust the air pressure in each air spring cylinder to adjust the total stiffness of all air springs to the stiffness value k calculated in Step 2. v ;

[0020] Step 4: Place the adjusted mobile measuring device on top of the bridge to be measured, start the measurement from one end of the bridge deck, and use the remote control to control the mobile measuring device to keep it moving evenly along the center line of the bridge deck. Each magnetoelectric vibration sensor collects the acceleration signal during the entire process until the device reaches the other end of the bridge deck to end the measurement.

[0021] Step 5: For each acceleration signal acquired by the magnetoelectric vibration sensor, the wireless dynamic acceleration test and analysis subsystem performs variational mode decomposition on the acceleration signal to obtain multiple components. A fast Fourier transform is then performed on each component to obtain the spectrum of each component during the movement of the mobile measuring device. The amplitude of the spectrum is then used to determine the bridge vibration component spectrum. The corresponding bridge frequency is then extracted from the bridge vibration component spectrum. The average value of the three bridge frequencies extracted from the acceleration signals acquired by the three magnetoelectric vibration sensors is taken to obtain the indirect measurement result of the bridge frequency.

[0022] Accordingly, the present invention also proposes a bridge frequency indirect measurement system based on a mobile measuring device, including a mobile measuring device, a theoretical frequency determination module, and an air spring stiffness calculation module;

[0023] The mobile measuring device includes:

[0024] One wirelessly controlled mobile inspection vehicle;

[0025] Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to pick up acceleration time history response signals during the measurement process;

[0026] Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle.

[0027] One wireless dynamic acceleration test and analysis subsystem is used to receive acceleration signals collected by various magnetoelectric vibration sensors and to process and analyze the acceleration signals.

[0028] The theoretical frequency determination module is used to simulate the bridge under test based on the finite element modeling software ANSYS, and to estimate the theoretical frequency of the bridge under test.

[0029] The air spring stiffness calculation module is used to back-calculate the frequency of the moving measuring device based on the theoretical frequency of the bridge under test and the preset ratio of the vehicle-bridge frequency, convert the frequency of the moving measuring device into angular frequency, and calculate the corresponding total air spring stiffness k. v The calculation formula is as follows:

[0030]

[0031] in, ω is the frequency of the moving measuring device, m v For the suspension quality of the wirelessly remote-controlled mobile inspection vehicle, m w For tire mass, k w For tire stiffness;

[0032] The wireless dynamic acceleration test and analysis subsystem includes a bridge vibration component extraction module and a frequency extraction and calculation module. By adjusting the air pressure in each air spring cylinder, the total stiffness of all air springs is adjusted to the stiffness value k calculated by the air spring stiffness calculation module. v Next, the adjusted mobile measuring device is placed above the bridge to be measured, and the measurement is started from one end of the bridge deck. The mobile measuring device is controlled by a remote control to keep moving evenly along the center line of the bridge deck until it reaches the other end of the bridge deck to end the measurement. The bridge vibration component extraction module receives the acceleration signals collected by each magnetoelectric vibration sensor during the movement. For each acceleration signal collected by the magnetoelectric vibration sensor, the bridge vibration component performs variational mode decomposition on the acceleration signal to obtain multiple components. The frequency extraction and calculation module performs fast Fourier transform on each component to obtain the spectrum diagram of each component during the movement of the mobile measuring device. Then, the bridge vibration component spectrum diagram is determined according to the amplitude of the spectrum diagram. The corresponding bridge frequency is then extracted from the bridge vibration component spectrum diagram. The frequency extraction and calculation module also takes the average value of the three bridge frequencies extracted from the acceleration signals collected by the three magnetoelectric vibration sensors to obtain the indirect measurement result of the bridge frequency.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) This invention not only avoids the closed traffic and complicated sensor deployment required by the traditional indirect bridge detection process, but also improves the detection accuracy and efficiency. It can perform targeted detection on different bridges by changing the parameters of the device itself.

[0035] (2) In view of the fact that most of the current bridge dynamic characteristic mobile indirect measurement devices require other vehicles to tow them, resulting in a complex coupling effect between the data acquisition device and the towing vehicle, this invention designs a new type of remote-controlled autonomous mobile measurement device, which has outstanding advantages such as strong portability, high intelligence and controllable driving status compared with other conventional devices.

[0036] (3) In view of the problem that the bridge vibration is masked by other signal components due to the superposition and mixing of vibration response signals from multiple excitation sources in the mobile measurement data, this invention uses variational mode decomposition to separate the bridge vibration component from the mixed signal, and performs time-frequency domain conversion analysis through fast Fourier transform to identify the bridge dynamic characteristics from the signal.

[0037] (4) In view of the problem that the accuracy of bridge frequency recognition is affected by the combined parameters of the bridge and the device, resulting in different measurement effects of a single device for different bridges, this invention proposes to optimize the recognition effect by changing the stiffness of the air spring based on the device-bridge coupling principle, so as to meet the needs of various application scenarios. Attached Figure Description

[0038] Figure 1 This is a flowchart of a bridge frequency indirect measurement method based on a mobile measuring device, disclosed in one embodiment of the present invention;

[0039] Figure 2 A simplified force analysis diagram of a mobile measuring device traveling on a bridge surface;

[0040] Figure 3 This is a schematic diagram of the entire bridge.

[0041] Figure 4 This is a schematic diagram of the bridge's cross-sectional dimensions;

[0042] Figure 5 The acceleration time history diagram of the moving measuring device;

[0043] Figure 6 The diagram shows the acceleration components of the bridge obtained after variational mode decomposition.

[0044] Figure 7 The spectrum obtained after Fast Fourier Transform;

[0045] Figure 8 This is a schematic diagram of a bridge frequency indirect measurement system based on a mobile measuring device, disclosed in another embodiment of the present invention. Detailed Implementation

[0046] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings and preferred embodiments.

[0047] like Figure 1 As shown, this embodiment of the invention provides a method for indirect measurement of bridge frequency based on a mobile measuring device, which specifically includes the following steps 1 to 5.

[0048] Step 1 (S1): Simulate the bridge under test using the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge under test.

[0049] Step 2 (S2): Based on the theoretical frequency of the bridge under test obtained in Step 1 and the preset vehicle-bridge frequency ratio, calculate the frequency of the moving measuring device, convert the frequency of the moving measuring device into angular frequency, and calculate the corresponding total stiffness k of the air spring suspension of the moving measuring device. v .

[0050] The motion measuring device used in this embodiment may include:

[0051] One wirelessly controlled mobile inspection vehicle, which can be a remotely controlled autonomous driving intelligent vehicle, has a sprung suspension mass of m. v =255kg, tire mass is m w =105kg, tire stiffness is k w =392kN / m;

[0052] Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to reduce single measurement errors and to pick up acceleration time history response signals during the measurement process.

[0053] Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle. The stiffness is changed by adjusting the air pressure in the cylinders, that is, the suspension stiffness of the mobile measuring device is adjusted, which in turn changes the frequency of the mobile measuring device. The ratio of the frequency of the mobile measuring device to that of the bridge is between 0.8 and 0.95 or 1.05 and 1.2, so as to achieve targeted measurement of different bridges.

[0054] A wireless dynamic acceleration test and analysis subsystem, used in conjunction with a magnetoelectric vibration sensor, is used to receive acceleration signals collected by each magnetoelectric vibration sensor and to process and analyze the acceleration signals.

[0055] To address the problem that most current mobile indirect measurement devices for bridge dynamic characteristics require towing by other vehicles, resulting in complex coupling effects between the data acquisition device and the towing vehicle, this invention designs a novel remotely controlled autonomous mobile measurement device. Compared with other conventional devices, it has outstanding advantages such as high portability, high intelligence, and controllable driving status.

[0056] Numerical simulation studies have found that during vehicle movement on the bridge surface, when the vehicle-to-bridge frequency ratio is within the range of 0.8–0.95 or 1.05–1.2, the bridge frequency peak is more pronounced in the frequency spectrum and easier to identify. Therefore, after obtaining the theoretical frequency of the bridge under test using the finite element software ANSYS, the frequency of the moving measuring device can be calculated according to the vehicle-to-bridge frequency ratio of 0.8–0.95 or 1.05–1.2, and then converted into angular frequency ω. (The last sentence appears to be incomplete and possibly refers to a different topic.) v Tire mass m w Tire stiffness k w Given all factors, the total stiffness k of the suspension air spring at the corresponding frequency can be calculated using vehicle dynamics principles. v .

[0057] The suspension mass m of the wirelessly controlled mobile inspection vehiclev Tire mass m w Tire stiffness k w Given all conditions, based on the principles of vehicle dynamics, a simplified force analysis is performed on the moving measuring device as it travels on the bridge surface. The analysis results are as follows: Figure 2 As shown in the figure, y v For the vertical displacement of the vehicle suspension, y w v is the vertical displacement of the wheel section, v is the vehicle speed, and u is the vertical displacement of the bridge. c Let be the vertical displacement at the contact point between the bridge and the wheel, x be the distance the wheel travels, m be the mass per meter, L be the bridge span, and EI be the measured stiffness of the main bridge beam. Based on the force analysis results and the corresponding dynamic equations, the total stiffness k of the air spring at the corresponding frequency can be calculated. v The specific calculation formula is as follows:

[0058]

[0059] in, ω is the angular frequency of the moving measuring device, m v For suspension mass, m w For tire mass, k w This refers to tire stiffness.

[0060] Step 3 (S3): Calculate the required total stiffness k of the air spring. v Then, using an electric air pump and other equipment, the air pressure in the air spring cylinders at the suspension is adjusted (the pressure value is checked by the pressure gauges connected at both ends) so that the total stiffness of all air springs, i.e. the suspension stiffness of the device, reaches the stiffness value k calculated in step 2. v .

[0061] To address the issue that the accuracy of bridge frequency recognition is affected by the combined parameters of the bridge and the device, resulting in different measurement effects of a single device for different bridges, this invention proposes to optimize the recognition effect by changing the stiffness of the air spring based on the device-bridge coupling principle, thereby meeting the needs of various application scenarios.

[0062] Step 4 (S4): Place the adjusted mobile measuring device above the bridge to be tested, start the measurement from one end of the bridge deck, and use a remote control to control the mobile measuring device to keep it moving at a uniform or approximately uniform speed along the center line of the bridge deck. Each magnetoelectric vibration sensor collects the acceleration signal during the entire process and sends the acceleration signal to the wireless dynamic acceleration test and analysis subsystem until the mobile measuring device moves to the other end of the bridge deck and ends the measurement.

[0063] Step 5 (S5): For each acceleration signal acquired by the magnetoelectric vibration sensor, the wireless dynamic acceleration test and analysis subsystem performs variational mode decomposition on the acceleration signal to obtain multiple components. These components include the bridge vibration component sensed by the tire contact with the bridge surface during the movement of the mobile measuring device, as well as vehicle vibration components, unevenness excitation components, etc. Then, a fast Fourier transform is performed on each component to obtain the spectrum diagram corresponding to each component during the movement of the mobile measuring device. The bridge vibration component spectrum diagram is determined based on the amplitude of the spectrum diagram, generally using the spectrum diagram with the largest amplitude. After determining the bridge vibration component spectrum diagram, frequency extraction can be performed based on it to extract a corresponding bridge frequency. After performing the above processing on the acceleration signals acquired by the three magnetoelectric vibration sensors, the wireless dynamic acceleration test and analysis subsystem can extract three bridge frequencies from the three different bridge vibration component spectrum diagrams. The average of the three bridge frequencies is then taken to reduce errors, ultimately obtaining the indirect measurement result of the bridge frequency, completing the indirect measurement of the bridge frequency through the mobile measuring device.

[0064] To address the problem that bridge vibration is masked by other signal components due to the superposition and mixing of vibration response signals from multiple excitation sources in mobile measurement data, this invention uses variational mode decomposition to separate the bridge vibration components from the mixed signal, and performs time-frequency domain conversion analysis through fast Fourier transform to identify the bridge dynamic characteristics from the signal.

[0065] Taking a simply supported beam bridge with a span of L = 30m as an example, the stiffness of the main beam is EI = 2.75 × 10⁻⁶. 10 N·m 2 The mass per linear meter is A schematic diagram of the bridge is shown below. Figure 3 As shown, the bridge cross-sectional dimensions are as follows: Figure 4 As shown. Calculations yield a theoretical bridge frequency of 2.667 Hz. The suspension mass of the moving measuring device is m. v =255kg, tire mass is m w =105kg, tire stiffness is k w =392kN / m. Based on the theoretical optimal range of the ratio of the frequency of the moving measuring device to that of the bridge, i.e., the preset vehicle-bridge frequency ratio of 0.8 to 0.95 or 1.05 to 1.2, the optimal range of the total stiffness of the air spring at the suspension is calculated to be 52.5 to 78.7kN / m or 101.5 to 146.7kN / m. In this embodiment, the total stiffness k of the air spring is selected. v =60kN / m, at which point the frequency of the moving measuring device is 2.265Hz, and the ratio of the moving measuring device frequency to the bridge frequency is 0.85. The random traffic flow parameters are set as shown in Table 1.

[0066] Table 1 Random Traffic Flow Parameter Data

[0067]

[0068] Under the above parameter settings, the device's moving speed is taken as v = 8 m / s. The acceleration response of the moving measuring device during the movement is obtained through numerical simulation calculation, such as... Figure 5 As shown. After performing variational mode decomposition, the obtained components are as follows: Figure 6 The IMF1 to IMF7 components are shown in the diagram. Each component is then subjected to a Fast Fourier Transform (FFT), and the spectrum of the IMF1 component is shown below. Figure 7 As shown in the figure, a distinct peak is observed, corresponding to a frequency of 2.66667 Hz, which is the same as the theoretical value for bridge frequency. The results indicate that the method and system of this invention can quickly and accurately measure bridge frequency indirectly while the device is moving on the bridge deck. The mobile measuring device can autonomously control its independent movement and can change its own frequency by altering the suspension stiffness, thus achieving the purpose of targeted measurement of bridges under different working conditions.

[0069] In another embodiment, such as Figure 8 As shown, the present invention also provides a bridge frequency indirect measurement system based on a mobile measuring device, which specifically includes a mobile measuring device, a theoretical frequency determination module, and an air spring stiffness calculation module.

[0070] The motion measuring device used in this embodiment may include:

[0071] One wirelessly controlled mobile inspection vehicle, which can be a remotely controlled autonomous driving intelligent vehicle, has a sprung suspension mass of m. v =255kg, tire mass is m w =105kg, tire stiffness is k w =392kN / m;

[0072] Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to reduce single measurement errors and to pick up acceleration time history response signals during the measurement process.

[0073] Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle. The stiffness is changed by adjusting the air pressure in the cylinders, that is, the suspension stiffness of the mobile measuring device is adjusted, which in turn changes the frequency of the mobile measuring device. The ratio of the frequency of the mobile measuring device to that of the bridge is between 0.8 and 0.95 or 1.05 and 1.2, so as to achieve targeted measurement of different bridges.

[0074] A wireless dynamic acceleration testing and analysis subsystem, used in conjunction with magnetoelectric vibration sensors, is employed to receive acceleration signals collected by the various magnetoelectric vibration sensors and to process and analyze these signals. The wireless dynamic acceleration testing and analysis subsystem includes a bridge vibration component extraction module and a frequency extraction and calculation module.

[0075] To address the problem that most current mobile indirect measurement devices for bridge dynamic characteristics require towing by other vehicles, resulting in complex coupling effects between the data acquisition device and the towing vehicle, this invention designs a novel remotely controlled autonomous mobile measurement device. Compared with other conventional devices, it has outstanding advantages such as high portability, high intelligence, and controllable driving status.

[0076] The theoretical frequency determination module is used to simulate the bridge under test based on the finite element modeling software ANSYS and estimate the theoretical frequency of the bridge under test.

[0077] The air spring stiffness calculation module is used to inversely calculate the frequency of the moving measuring device based on the ratio of the theoretical frequency of the bridge under test and the preset vehicle-bridge frequency. It then converts the frequency of the moving measuring device into an angular frequency and calculates the corresponding total stiffness k of the air springs in the moving measuring device's suspension. v .

[0078] Numerical simulation studies have found that during vehicle movement on the bridge surface, when the vehicle-to-bridge frequency ratio is within the range of 0.8–0.95 or 1.05–1.2, the bridge frequency peak is more pronounced in the frequency spectrum and easier to identify. Therefore, after the theoretical frequency determination module obtains the theoretical frequency of the bridge under test using the finite element software ANSYS, the air spring stiffness calculation module can calculate the frequency of the moving measuring device according to the vehicle-to-bridge frequency ratio of 0.8–0.95 or 1.05–1.2, and convert it into angular frequency ω. (The last sentence appears to be incomplete and possibly refers to a different topic.) v Tire mass m w Tire stiffness k w Given all factors, the total stiffness k of the suspension air spring at the corresponding frequency can be calculated using vehicle dynamics principles. v .

[0079] The suspension mass m of the wirelessly controlled mobile inspection vehicle v Tire mass m w Tire stiffness k w Given all conditions, based on the principles of vehicle dynamics, a simplified force analysis is performed on the moving measuring device as it travels on the bridge surface. The analysis results are as follows: Figure 2 As shown in the figure, y v For the vertical displacement of the vehicle suspension, y w v is the vertical displacement of the wheel section, v is the vehicle speed, and u is the vertical displacement of the bridge. cLet x be the vertical displacement at the contact point between the bridge and the wheel, m be the mass per meter, L be the bridge span, and EI be the measured stiffness of the main bridge beam. Based on the force analysis results and the corresponding dynamic equations, the air spring stiffness calculation module can calculate the total stiffness k of the air spring at the corresponding frequency. v The specific calculation formula is as follows:

[0080]

[0081] in, ω is the angular frequency of the moving measuring device, m v For suspension mass, m w For tire mass, k w This refers to tire stiffness.

[0082] The required total air spring stiffness k is calculated using the air spring stiffness calculation module. v Then, using equipment such as an electric air pump, the air pressure inside the air spring cylinder at the suspension is adjusted (the pressure value is checked by pressure gauges connected at both ends) so that the total stiffness of the air spring, i.e. the suspension stiffness of the device, reaches the calculated stiffness value k. v .

[0083] To address the issue that the accuracy of bridge frequency recognition is affected by the combined parameters of the bridge and the device, resulting in different measurement effects of a single device for different bridges, this invention proposes to optimize the recognition effect by changing the stiffness of the air spring based on the device-bridge coupling principle, thereby meeting the needs of various application scenarios.

[0084] By adjusting the air pressure in each air spring cylinder, the total stiffness of all air springs is adjusted to the stiffness value k calculated by the air spring stiffness calculation module. vNext, the adjusted mobile measuring device is placed above the bridge under test. Measurement begins from one end of the bridge deck, and the device is controlled by a remote controller to maintain a uniform or approximately uniform speed along the centerline of the bridge deck until it reaches the other end. The bridge vibration component extraction module in the wireless dynamic acceleration test and analysis subsystem receives acceleration signals collected by various magnetoelectric vibration sensors during the travel process. For each acceleration signal collected by a magnetoelectric vibration sensor, the module performs variational mode decomposition to obtain multiple components. These components include the bridge vibration components sensed by the contact between the tires and the bridge deck during the travel of the mobile measuring device, as well as vehicle vibration components, unevenness excitation components, etc. The module then performs a fast Fourier transform on each component to obtain the corresponding spectrum of each component during the travel of the mobile measuring device. The bridge vibration component spectrum is determined based on the amplitude of the spectrum, generally using the spectrum with the largest amplitude as the bridge vibration component spectrum. The frequency extraction and calculation module in the wireless dynamic acceleration test and analysis subsystem extracts the frequency from the bridge vibration component spectrum obtained by the bridge vibration component extraction module, thus extracting a corresponding bridge frequency. After the bridge vibration component extraction module and the frequency extraction and calculation module perform the above processing on the acceleration signals collected by the three magnetoelectric vibration sensors, three bridge frequencies can be extracted from the three different bridge vibration component spectrums. The frequency extraction and calculation module then takes the average of the three bridge frequencies to reduce errors, and finally obtains the indirect measurement result of the bridge frequency, completing the indirect measurement of the bridge frequency through the moving measuring device.

[0085] To address the problem that bridge vibration is masked by other signal components due to the superposition and mixing of vibration response signals from multiple excitation sources in mobile measurement data, this invention uses variational mode decomposition to separate the bridge vibration components from the mixed signal, and performs time-frequency domain conversion analysis through fast Fourier transform to identify the bridge dynamic characteristics from the signal.

[0086] The method and system of this invention not only avoid the closed traffic and complex sensor deployment required by the traditional indirect bridge inspection process, but also improve the detection accuracy and efficiency, and can perform targeted inspections on different bridges by changing the parameters of the device itself.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The technical features of the embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been described. For those skilled in the art, the present invention can have various modifications and variations. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, as long as the combination of these technical features does not contradict each other, should be included within the protection scope of the present invention.

[0088] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for indirect measurement of bridge frequency based on a mobile measuring device, characterized in that, The mobile measuring device includes: One wirelessly controlled mobile inspection vehicle; Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to pick up acceleration time history response signals during the measurement process; Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle. One wireless dynamic acceleration test and analysis subsystem is used to receive acceleration signals collected by various magnetoelectric vibration sensors and to process and analyze the acceleration signals. The indirect bridge frequency measurement method includes the following steps: Step 1: Simulate the bridge under test using the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge under test. Step 2: Calculate the frequency of the moving measuring device based on the ratio of the theoretical frequency of the bridge to be measured to the preset vehicle-bridge frequency. Convert the frequency of the moving measuring device into angular frequency and calculate the corresponding total stiffness k of the air spring. v The calculation formula is as follows: in, ω is the angular frequency of the moving measuring device, m v For the suspension quality of the wirelessly remote-controlled mobile inspection vehicle, m w For tire mass, k w For tire stiffness; Step 3: Adjust the air pressure in each air spring cylinder to adjust the total stiffness of all air springs to the stiffness value k calculated in Step 2. v ; Step 4: Place the adjusted mobile measuring device on the bridge to be measured, start the measurement from one end of the bridge deck, use the remote control to control the mobile measuring device to keep moving evenly along the center line of the bridge deck, and collect the acceleration signal of each magnetoelectric vibration sensor throughout the process until the other end of the bridge deck is reached to end the measurement. Step 5: For each acceleration signal acquired by the magnetoelectric vibration sensor, the wireless dynamic acceleration test and analysis subsystem performs variational mode decomposition on the acceleration signal to obtain multiple components. A fast Fourier transform is then performed on each component to obtain the spectrum diagram corresponding to each component during the movement of the mobile measuring device. The amplitude of the spectrum diagram is then used to determine the bridge vibration component spectrum diagram. The corresponding bridge frequency is then extracted from the bridge vibration component spectrum diagram. The average value of the three bridge frequencies extracted from the acceleration signals acquired by the three magnetoelectric vibration sensors is taken to obtain the indirect measurement result of the bridge frequency.

2. The method for indirect bridge frequency measurement based on a mobile measuring device according to claim 1, characterized in that, The preset axle frequency ratio ranges from 0.8 to 0.95 or from 1.05 to 1.

2.

3. A method for indirect bridge frequency measurement based on a mobile measuring device according to claim 1 or 2, characterized in that, The suspension mass of the wireless remote-controlled mobile inspection vehicle is m. v =255kg, the tire mass is m w =105kg, tire stiffness is k w =392kN / m.

4. A method for indirect bridge frequency measurement based on a mobile measuring device according to claim 1 or 2, characterized in that, An electric air pump is used to adjust the air pressure inside the air spring cylinder.

5. A bridge frequency indirect measurement system based on a mobile measuring device, characterized in that, Includes a mobile measuring device, a theoretical frequency determination module, and an air spring stiffness calculation module; The mobile measuring device includes: One wirelessly controlled mobile inspection vehicle; Three magnetoelectric vibration sensors are respectively deployed at the center of the wireless remote-controlled mobile inspection vehicle and on the top plate directly above the front and rear axles to pick up acceleration time history response signals during the measurement process; Four air springs with adjustable stiffness are installed on the suspension of the four wheels of the wireless remote-controlled mobile inspection vehicle. One wireless dynamic acceleration test and analysis subsystem is used to receive acceleration signals collected by various magnetoelectric vibration sensors and to process and analyze the acceleration signals. The theoretical frequency determination module is used to simulate the bridge under test based on the finite element modeling software ANSYS, and to estimate the theoretical frequency of the bridge under test. The air spring stiffness calculation module is used to back-calculate the frequency of the moving measuring device based on the theoretical frequency of the bridge under test and the preset ratio of the vehicle-bridge frequency, convert the frequency of the moving measuring device into angular frequency, and calculate the corresponding total air spring stiffness k. v The calculation formula is as follows: in, ω is the angular frequency of the moving measuring device, m v For the suspension quality of the wirelessly remote-controlled mobile inspection vehicle, m w For tire mass, k w For tire stiffness; The wireless dynamic acceleration test and analysis subsystem includes a bridge vibration component extraction module and a frequency extraction and calculation module. By adjusting the air pressure in each air spring cylinder, the total stiffness of all air springs is adjusted to the stiffness value k calculated by the air spring stiffness calculation module. v Next, the adjusted mobile measuring device is placed above the bridge to be measured, and the measurement is started from one end of the bridge deck. The mobile measuring device is controlled by a remote control to keep moving evenly along the center line of the bridge deck until it reaches the other end of the bridge deck to end the measurement. The bridge vibration component extraction module receives the acceleration signals collected by each magnetoelectric vibration sensor during the movement. For each acceleration signal collected by the magnetoelectric vibration sensor, the bridge vibration component extraction module performs variational mode decomposition on the acceleration signal to obtain multiple components. The frequency extraction and calculation module performs fast Fourier transform on each component to obtain the spectrum diagram of each component during the movement of the mobile measuring device. Then, the bridge vibration component spectrum diagram is determined according to the amplitude of the spectrum diagram. The corresponding bridge frequency is then extracted from the bridge vibration component spectrum diagram. The frequency extraction and calculation module also takes the average value of the three bridge frequencies extracted from the acceleration signals collected by the three magnetoelectric vibration sensors to obtain the indirect measurement result of the bridge frequency.

6. The bridge frequency indirect measurement system based on a mobile measuring device according to claim 5, characterized in that, The preset axle frequency ratio ranges from 0.8 to 0.95 or from 1.05 to 1.

2.

7. A bridge frequency indirect measurement system based on a mobile measuring device according to claim 5 or 6, characterized in that, The suspension mass of the wireless remote-controlled mobile inspection vehicle is m. v =255kg, the tire mass is m w =105kg, tire stiffness is k w =392kN / m.

8. A bridge frequency indirect measurement system based on a mobile measuring device according to claim 5 or 6, characterized in that, The mobile measuring device also includes an electric air pump for adjusting the air pressure inside the air spring cylinder.

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