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

Abstract

The invention relates to a bridge frequency indirect measurement method and system based on a mobile measurement device, and belongs to the field of bridge engineering measurement. Firstly, the theoretical frequency of a to-be-measured bridge is estimated, the device frequency is inversely calculated according to the theoretical frequency and the preset axle frequency ratio, and the total rigidity of an air spring is calculated; after the total rigidity of the air spring is adjusted to a calculated value, the device is placed on a bridge to be tested to run, the wireless dynamic acceleration test analysis subsystem carries out variational mode decomposition on acceleration signals collected by all the magnetoelectric vibration sensors, fast Fourier transform is carried out on the obtained multiple components, and a spectrogram is obtained; determining a bridge vibration component spectrogram, extracting bridge frequency, and averaging the bridge frequency extracted from the bridge vibration component spectrogram of each sensor signal to obtain a bridge frequency indirect measurement result. According to the invention, traffic closing and complicated arrangement of sensors are not needed, the detection precision and efficiency are high, and the bridge can be detected in a targeted manner by changing the parameters of the device.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge engineering measurement, and in particular relates to a bridge frequency indirect measurement method and system based on a mobile measurement device. Background Art

[0002] Bridges are key nodes in transportation infrastructure. As their service life increases, bridge structures will inevitably experience performance degradation. In order to ensure the safe operation of bridge structures, how to accurately grasp the use status of bridge structures is a pain point for bridge maintenance departments and a technical difficulty. Bridge inspection is an effective technical means to assess the use status of bridges. Frequency is one of the key dynamic performance indicators of bridge structures and is widely used in early warning, damage identification and status assessment of bridge structures. Faced with a large number of wide-ranging bridge structures, how to quickly detect the frequency of bridges is a technical problem that needs to be solved urgently.

[0003] Traditional detection methods require closing off traffic flow and deploying numerous sensors on bridges. This method takes a long time to measure bridge frequency, is costly, and is not suitable for rapid testing. In summary, the traditional frequency calculation method has the problems of slow detection speed and low accuracy.

[0004] At present, the number of highway bridges in my country has exceeded 1 million, and there are tens of thousands of urban bridges. Facing the needs of large-scale bridge safety inspection, the disadvantages of traditional bridge frequency measurement methods are becoming increasingly prominent and can no longer meet the needs of bridge structure safety assurance. Therefore, it is urgent to provide a bridge frequency measurement method with fast inspection speed and high inspection accuracy.

[0005] The invention patent with publication number CN112362272A provides a measuring vehicle system for bridge frequency signal enhancement identification, which indirectly obtains bridge frequency signals through the design of the measuring vehicle system. However, the measuring vehicle system adopts a tractor plus measuring vehicle mode, the measuring vehicle cannot travel independently, and the measuring vehicle parameters are fixed and cannot be adjusted, so it is impossible to carry out targeted measurements on bridges under different working conditions.

[0006] The invention patent with the publication number CN116842775A discloses a bridge modal vibration driving identification method that eliminates the influence of road surface roughness, and the invention patent with the publication number CN116481747A discloses a bridge modal vibration driving identification method that considers the influence of bridge damping. Both methods are to establish two measuring vehicle-bridge models and use the measuring vehicle-bridge vertical contact response to construct the bridge modal vibration. However, this method uses a moving and stationary measuring vehicle-bridge system, and the two vehicles are arranged on the bridge for measurement. The system cannot measure completely in motion, and there is still a problem of fixed parameters and non-adjustable parameters, and it is impossible to effectively measure different bridges. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a method and system for indirect measurement of bridge frequency based on a mobile measuring device, so as to realize fast and accurate detection of bridge frequency.

[0008] The technical solution adopted by the present invention is as follows:

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

[0010] 1 wireless remote control mobile inspection vehicle;

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

[0012] Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle;

[0013] 1 wireless dynamic acceleration test and analysis subsystem, used to receive the acceleration signals collected by each magnetoelectric vibration sensor, and process and analyze the acceleration signals;

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

[0015] Step 1: Simulate the bridge to be tested based on the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge to be tested;

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

[0017]

[0018] in, ω is the angular frequency of the mobile measuring device, m v is the mass of the suspension of the wireless remote control mobile inspection vehicle, m w is the tire mass, k w is the 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 above the bridge to be measured, start measuring from one end of the bridge deck, and use a remote control to control the mobile measuring device to keep moving evenly along the center line of the bridge deck road. Each magnetoelectric vibration sensor collects acceleration signals during the entire process until it reaches the other end of the bridge deck and ends the measurement.

[0021] Step 5: For each acceleration signal collected by the magnetoelectric vibration sensor, the wireless dynamic acceleration test analysis subsystem performs variational modal decomposition on the acceleration signal to obtain multiple components, and performs fast Fourier transform on each component to obtain the frequency spectrum of each component during the driving process of the corresponding mobile measuring device. The spectrum of the bridge vibration component is then determined according to the amplitude of the spectrum, and the corresponding bridge frequency is extracted according to the spectrum of the bridge vibration component. The average of the three bridge frequencies extracted from the acceleration signals collected 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 measurement device, comprising a mobile measurement device, a theoretical frequency determination module and an air spring stiffness calculation module;

[0023] The mobile measuring device comprises:

[0024] 1 wireless remote control mobile inspection vehicle;

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

[0026] Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle;

[0027] 1 wireless dynamic acceleration test and analysis subsystem, used to receive the acceleration signals collected by each magnetoelectric vibration sensor, and process and analyze the acceleration signals;

[0028] The theoretical frequency determination module is used to simulate the bridge to be tested based on the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge to be tested;

[0029] The air spring stiffness calculation module is used to calculate the frequency of the mobile measuring device according to the theoretical frequency of the bridge to be measured and the preset bridge frequency ratio, convert the frequency of the mobile measuring device into an angular frequency and calculate the corresponding total stiffness k of the air spring. v , the calculation formula is as follows:

[0030]

[0031] in, ω is the frequency of the mobile measuring device, m v is the mass of the suspension of the wireless remote control mobile inspection vehicle, m w is the tire mass, k w is the 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. When 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 Afterwards, 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 road until it reaches the other end of the bridge deck and ends the measurement. The bridge vibration component extraction module receives the acceleration signals collected by each magnetoelectric vibration sensor during the driving process. For each acceleration signal collected by the magnetoelectric vibration sensor, the bridge vibration component performs variational modal 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 frequency spectrum of each component during the driving process of the corresponding mobile measuring device, and then determines the bridge vibration component spectrum according to the amplitude of the spectrum, and then extracts the corresponding bridge frequency according to the bridge vibration component spectrum. The frequency extraction and calculation module also takes the average of the three bridge frequencies extracted from the acceleration signals collected by the three magnetoelectric vibration sensors to obtain an indirect measurement result of the bridge frequency.

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

[0034] (1) The present invention not only avoids the closed traffic and complicated deployment of sensors required in the traditional bridge indirect detection process, but also improves the detection accuracy and efficiency, and can perform targeted detection on different bridges to be tested by changing the parameters of the device itself;

[0035] (2) In view of the problem that most of the current mobile indirect measurement devices for bridge dynamic characteristics need to be towed by other vehicles, resulting in complex coupling effects between the collection device and the towing vehicle, the present invention designs a new type of mobile measurement device that can be remotely controlled and autonomously driven. Compared with other conventional devices, it has outstanding advantages such as strong portability, high intelligence, and controllable driving state;

[0036] (3) To address the problem that the vibration response signals of multiple excitation sources are superimposed and mixed in the mobile measurement data, resulting in the bridge vibration being masked by other signal components, the present invention uses the variational mode decomposition method 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 order to address the problem that the accuracy of bridge frequency recognition is affected by the combined influence of various parameters of the bridge and the device, resulting in different measurement effects of a single device on different bridges, the present invention proposes to optimize the recognition effect based on the device-bridge coupling principle by changing the stiffness of the air spring, thereby meeting the needs of various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a bridge frequency indirect measurement method based on a mobile measurement device disclosed in one embodiment of the present invention;

[0039] Figure 2 This is a simplified force analysis diagram of the mobile measuring device traveling on the bridge deck;

[0040] Figure 3 This is the overall schematic diagram of the bridge;

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

[0042] Figure 5 is the acceleration time history diagram of the mobile measurement device;

[0043] Figure 6 The acceleration component diagram of the bridge is obtained after variational mode decomposition;

[0044] Figure 7 is the spectrum obtained after fast Fourier transform;

[0045] Figure 8 A schematic structural diagram of a bridge frequency indirect measurement system based on a mobile measurement device disclosed in another embodiment of the present invention. DETAILED DESCRIPTION

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

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

[0048] Step 1 (S1): The bridge to be tested is simulated based on the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge to be tested.

[0049] Step 2 (S2): According to the theoretical frequency of the bridge to be measured obtained in step 1 and the preset bridge frequency ratio, the frequency of the mobile measuring device is calculated, the frequency of the mobile measuring device is converted into an angular frequency, and the corresponding total stiffness k of the suspension air spring of the mobile measuring device is calculated. v .

[0050] The mobile measurement device used in this embodiment may include:

[0051] 1 wireless remote control mobile inspection vehicle, which can be a remote control autonomous intelligent vehicle with a spring 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 arranged at the center of the wireless remote control mobile inspection vehicle and on the top plate just above the front and rear axles to reduce the single measurement error and to pick up the acceleration time history response signal during the measurement process;

[0053] Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle. The stiffness is changed by adjusting the air pressure in the cylinder, that is, the suspension stiffness of the mobile measuring device is adjusted, and then the frequency of the mobile measuring device is changed, so that the ratio of the frequency of the mobile measuring device to 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] 1 wireless dynamic acceleration test and analysis subsystem, used in conjunction with the magnetoelectric vibration sensor, for receiving the acceleration signals collected by each magnetoelectric vibration sensor, and processing and analyzing the acceleration signals.

[0055] In view of the problem that most of the current mobile indirect measurement devices for bridge dynamic characteristics need to be towed by other vehicles, which leads to complex coupling effects between the collection device and the towing vehicle, the present invention designs a new type of mobile measurement device that can be remotely controlled and driven autonomously. Compared with other conventional devices, it has outstanding advantages such as strong portability, high intelligence, and controllable driving status.

[0056] Numerical simulation studies have found that when the vehicle moves on the bridge deck, when the vehicle-bridge frequency ratio is in the range of 0.8-0.95 or 1.05-1.2, the bridge frequency peak is more obvious in the spectrum diagram and is easier to identify. Therefore, after obtaining the theoretical frequency of the bridge to be tested through the finite element software ANSYS, the frequency of the mobile measurement device can be calculated according to the vehicle-bridge frequency ratio of 0.8-0.95 or 1.05-1.2, and converted into angular frequency ω. v , tire mass m w , tire stiffness k w When all are determined, the total stiffness k of the suspension air spring at the corresponding frequency can be obtained through the principle of vehicle dynamics: v .

[0057] The mass of the suspension m in the wireless remote control mobile inspection vehiclev , tire mass m w , tire stiffness k w When all are determined, a simplified force analysis is performed on the mobile measuring device on the bridge deck according to the principle of vehicle dynamics. The analysis results are as follows: Figure 2 As shown in the figure, y v is the vertical displacement of the vehicle suspension, y w is the vertical displacement of the wheel, v is the vehicle speed, u is the vertical displacement of the bridge, u c is the vertical displacement at the contact point between the bridge and the wheel, x is the wheel travel distance, m is the mass per linear meter, L is the bridge span, and EI is the measured bridge girder stiffness. Based on the force analysis results and the corresponding dynamic equation, 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 mobile measuring device, m v is the mass of the suspension, m w is the tire mass, k w is the tire stiffness.

[0060] Step 3 (S3): Calculate the required total stiffness k of the air spring v Finally, use an electric air pump or other equipment to adjust the air pressure in the air spring cylinder at the suspension (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 stiffness of the device suspension, reaches the stiffness value k calculated in step 2. v .

[0061] In order to solve the problem that the accuracy of bridge frequency recognition is affected by the comprehensive influence of various parameters of the bridge and the device, resulting in different measurement effects of a single device on different bridges, the present invention proposes to optimize the recognition effect based on the device-bridge coupling principle by changing the stiffness of the air spring, so as to meet the needs of various application scenarios.

[0062] Step 4 (S4): Place the adjusted mobile measuring device above the bridge to be tested, start measuring from one end of the bridge deck, use a remote control to control the mobile measuring device to maintain a uniform or approximately uniform speed along the center line of the bridge deck road, and each magnetoelectric vibration sensor collects acceleration signals during the driving process, and sends the acceleration signals to the wireless dynamic acceleration test and analysis subsystem until the mobile measuring device drives to the other end of the bridge deck to end the measurement.

[0063] Step 5 (S5): For each acceleration signal collected by the magnetoelectric vibration sensor, the wireless dynamic acceleration test and analysis subsystem performs variational modal decomposition on the acceleration signal to obtain multiple components, including the bridge vibration component sensed by the tire and bridge deck contact during the driving process of the mobile measuring device, as well as the vehicle vibration component, the unevenness excitation component, etc. Then, each component is subjected to fast Fourier transform to obtain the spectrum corresponding to each component during the driving process of the mobile measuring device, and the spectrum of the bridge vibration component is determined according to the amplitude of the spectrum. Generally, the spectrum with the largest spectrum amplitude is used as the spectrum of the bridge vibration component. After determining the spectrum of the bridge vibration component, frequency extraction can be performed according to the spectrum of the bridge vibration component to extract a corresponding bridge frequency. After the wireless dynamic acceleration test and analysis subsystem performs 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, and then the three bridge frequencies are averaged to reduce the error, and finally the indirect measurement result of the bridge frequency is obtained, completing the indirect measurement of the bridge frequency by the mobile measuring device.

[0064] In order to solve the problem that the vibration response signals of multiple excitation sources are superimposed and mixed in the mobile measurement data, resulting in the bridge vibration being masked by other signal components, the present invention uses the variational mode decomposition method to separate the bridge vibration component from the mixed signal, and performs time-frequency domain conversion analysis through fast Fourier transform to identify the dynamic characteristics of the bridge from the signal.

[0065] Taking a simply supported beam bridge with a span of L = 30m as an example, the stiffness of the bridge main beam is EI = 2.75×10 10 N·m 2 , the mass per linear meter is The overall schematic diagram of the bridge is as follows Figure 3 The cross-sectional dimensions of the bridge are shown in Figure 4 As shown. After calculation, the theoretical solution of the bridge frequency is 2.667Hz. The suspension mass of the mobile measuring device is m v =255kg, tire mass is m w =105kg, tire stiffness is k w =392 kN / m, according to the theoretical optimal range of the ratio of the frequency of the mobile measuring device to the bridge, that is, 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 78.7 kN / m or 101.5 to 146.7 kN / m. v =60kN / m, the frequency of the mobile measuring device is 2.265Hz, and the ratio of the mobile measuring device to the bridge frequency is 0.85. The random traffic flow parameter settings are shown in Table 1.

[0066] Table 1 Random traffic flow parameter data

[0067]

[0068] Under the above parameter settings, the moving speed of the device is taken as v = 8m / s, and the acceleration response of the mobile measuring device during the moving process is obtained through numerical simulation calculation, such as Figure 5 After performing variational mode decomposition, the components obtained are as follows Figure 6 As shown in IMF1 to IMF7. Each component is subjected to fast Fourier transform, and the spectrum of IMF1 component is as follows Figure 7 As shown, it can be seen that there is an obvious peak in the figure, and the corresponding frequency is 2.66667Hz, which is the same as the theoretical value of the bridge frequency. The results show that the method and system of the present invention can quickly and accurately measure the bridge frequency indirectly during the movement on the bridge deck. The mobile measurement device can control its own independent driving and can change the frequency of the device itself by changing the suspension stiffness, so as to achieve the purpose of targeted measurement of bridges under different working conditions.

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

[0070] The mobile measurement device used in this embodiment may include:

[0071] 1 wireless remote control mobile inspection vehicle, which can be a remote control autonomous intelligent vehicle with a spring 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 arranged at the center of the wireless remote control mobile inspection vehicle and on the top plate just above the front and rear axles to reduce the single measurement error and to pick up the acceleration time history response signal during the measurement process;

[0073] Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle. The stiffness is changed by adjusting the air pressure in the cylinder, that is, the suspension stiffness of the mobile measuring device is adjusted, and then the frequency of the mobile measuring device is changed, so that the ratio of the frequency of the mobile measuring device to 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] 1 wireless dynamic acceleration test and analysis subsystem, used in conjunction with the magnetoelectric vibration sensor, is used to receive the acceleration signals collected by each magnetoelectric vibration sensor and process and analyze the acceleration signals. The wireless dynamic acceleration test and analysis subsystem includes a bridge vibration component extraction module and a frequency extraction and calculation module.

[0075] In view of the problem that most of the current mobile indirect measurement devices for bridge dynamic characteristics need to be towed by other vehicles, which leads to complex coupling effects between the collection device and the towing vehicle, the present invention designs a new type of mobile measurement device that can be remotely controlled and driven autonomously. Compared with other conventional devices, it has outstanding advantages such as strong portability, high intelligence, and controllable driving status.

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

[0077] The air spring stiffness calculation module is used to calculate the frequency of the mobile measuring device according to the theoretical frequency of the bridge to be measured and the preset bridge frequency ratio, convert the frequency of the mobile measuring device into angular frequency and calculate the total stiffness k of the suspension air spring of the corresponding mobile measuring device. v .

[0078] Numerical simulation studies have found that when the vehicle moves on the bridge deck, when the vehicle-bridge frequency ratio is in the range of 0.8-0.95 or 1.05-1.2, the bridge frequency peak is more obvious in the spectrum diagram and is easier to identify. Therefore, after the theoretical frequency determination module obtains the theoretical frequency of the bridge to be tested through the finite element software ANSYS, the air spring stiffness calculation module can calculate the frequency of the mobile measurement device according to the vehicle-bridge frequency ratio of 0.8-0.95 or 1.05-1.2, and convert it into an angular frequency ω. v , tire mass m w , tire stiffness k w When all are determined, the total stiffness k of the suspension air spring at the corresponding frequency can be obtained through the principle of vehicle dynamics: v .

[0079] The mass of the suspension m in the wireless remote control mobile inspection vehicle v , tire mass m w , tire stiffness k w When all are determined, a simplified force analysis is performed on the mobile measuring device on the bridge deck according to the principle of vehicle dynamics. The analysis results are as follows: Figure 2 As shown in the figure, y v is the vertical displacement of the vehicle suspension, y w is the vertical displacement of the wheel, v is the vehicle speed, u is the vertical displacement of the bridge, u cis the vertical displacement at the contact point between the bridge and the wheel, x is the wheel travel distance, m is the mass per linear meter, L is the bridge span, and EI is the measured bridge girder stiffness. 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 mobile measuring device, m v is the mass of the suspension, m w is the tire mass, k w is the tire stiffness.

[0082] The required total air spring stiffness k is calculated in the air spring stiffness calculation module. v Finally, use an electric air pump or other equipment to adjust the air pressure in the air spring cylinder at the suspension (the pressure value is checked by the pressure gauge connected at both ends) so that the total stiffness of the air spring, i.e. the stiffness of the device suspension, reaches the calculated stiffness value k. v .

[0083] In order to solve the problem that the accuracy of bridge frequency recognition is affected by the comprehensive influence of various parameters of the bridge and the device, resulting in different measurement effects of a single device on different bridges, the present invention proposes to optimize the recognition effect based on the device-bridge coupling principle by changing the stiffness of the air spring, so as to meet 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. vAfter that, the adjusted mobile measuring device is placed above the bridge to be tested, and the measurement is started from one end of the bridge deck. The mobile measuring device is controlled by a remote controller to maintain a uniform or approximately uniform speed along the center line of the bridge deck road until the mobile measuring device reaches the other end of the bridge deck and ends the measurement. The bridge vibration component extraction module in the wireless dynamic acceleration test and analysis subsystem receives the acceleration signals collected by each magnetoelectric vibration sensor during the driving process. For each acceleration signal collected by the magnetoelectric vibration sensor, the bridge vibration component extraction module performs variational modal decomposition on the acceleration signal to obtain multiple components, including the bridge vibration component sensed by the mobile measuring device during the driving process when the tire contacts the bridge deck, as well as the vehicle vibration component, the unevenness excitation component, and the like. The bridge vibration component extraction module then performs fast Fourier transform on each component to obtain the spectrum corresponding to each component during the driving process of the mobile measuring device, and determines the bridge vibration component spectrum according to the amplitude of the spectrum. Generally, the spectrum with the largest spectrum amplitude is used as the bridge vibration component spectrum. The frequency extraction and calculation module in the wireless dynamic acceleration test and analysis subsystem performs frequency extraction based on the bridge vibration component spectrum obtained by the bridge vibration component extraction module, and extracts 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 three different bridge vibration component spectrums. The frequency extraction and calculation module then takes the average of the three bridge frequencies to reduce the error, and finally obtains the indirect measurement result of the bridge frequency, completing the indirect measurement of the bridge frequency through the mobile measurement device.

[0085] In order to solve the problem that the vibration response signals of multiple excitation sources are superimposed and mixed in the mobile measurement data, resulting in the bridge vibration being masked by other signal components, the present invention uses the variational mode decomposition method to separate the bridge vibration component from the mixed signal, and performs time-frequency domain conversion analysis through fast Fourier transform to identify the dynamic characteristics of the bridge from the signal.

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

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The various technical features of the embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of the various technical features in the above embodiments are not described. For those skilled in the art, the present invention can have various changes and variations. However, within the spirit and principles of the present invention, as long as there is no contradiction in the combination of these technical features, any modifications, equivalent substitutions, improvements, etc. made should be included in the protection scope of the present invention.

[0088] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A bridge frequency indirect measurement method based on a mobile measurement device, characterized in that: The mobile measuring device comprises: 1 wireless remote control mobile inspection vehicle; Three magnetoelectric vibration sensors are respectively arranged at the center of the wireless remote control mobile inspection vehicle and on the top plate just above the front and rear axles to pick up the acceleration time-history response signals during the measurement process; Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle; 1 wireless dynamic acceleration test and analysis subsystem, used to receive the acceleration signals collected by each magnetoelectric vibration sensor, and process and analyze the acceleration signals; The bridge frequency indirect measurement method comprises the following steps: Step 1: Simulate the bridge to be tested based on the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge to be tested; Step 2: Calculate the frequency of the mobile measuring device based on the theoretical frequency of the bridge to be tested and the preset bridge frequency ratio, convert the frequency of the mobile 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 mobile measuring device, m v is the mass of the suspension of the wireless remote control mobile inspection vehicle, m w is the tire mass, k w is the 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 above the bridge to be measured, start measuring from one end of the bridge deck, and use a remote control to control the mobile measuring device to keep moving evenly along the center line of the bridge deck road. Each magnetoelectric vibration sensor collects acceleration signals during the entire process until it reaches the other end of the bridge deck and ends the measurement. Step 5: For each acceleration signal collected by the magnetoelectric vibration sensor, the wireless dynamic acceleration test analysis subsystem performs variational modal decomposition on the acceleration signal to obtain multiple components, and performs fast Fourier transform on each component to obtain the spectrum diagram corresponding to each component during the driving process of the mobile measuring device. The spectrum diagram of the bridge vibration component is then determined according to the amplitude of the spectrum diagram, and then the corresponding bridge frequency is extracted according to the spectrum diagram of the bridge vibration component. The three bridge frequencies extracted from the acceleration signals collected by the three magnetoelectric vibration sensors are averaged to obtain the indirect measurement result of the bridge frequency.

2. The indirect bridge frequency measurement method based on a mobile measurement device according to claim 1 is characterized in that: The preset range of the axle frequency ratio is 0.8 to 0.95 or 1.05 to 1.

2.

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

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

5. A bridge frequency indirect measurement system based on a mobile measurement device, characterized in that: It includes a mobile measuring device, a theoretical frequency determination module and an air spring stiffness calculation module; The mobile measuring device comprises: 1 wireless remote control mobile inspection vehicle; Three magnetoelectric vibration sensors are respectively arranged at the center of the wireless remote control mobile inspection vehicle and on the top plate just above the front and rear axles to pick up the acceleration time-history response signals during the measurement process; Four air springs with adjustable stiffness are installed on the suspension parts of the four wheels of the wireless remote control mobile inspection vehicle; 1 wireless dynamic acceleration test and analysis subsystem, used to receive the acceleration signals collected by each magnetoelectric vibration sensor, and process and analyze the acceleration signals; The theoretical frequency determination module is used to simulate the bridge to be tested based on the finite element modeling software ANSYS to estimate the theoretical frequency of the bridge to be tested; The air spring stiffness calculation module is used to calculate the frequency of the mobile measuring device according to the theoretical frequency of the bridge to be measured and the preset bridge frequency ratio, convert the frequency of the mobile measuring device into an 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 mobile measuring device, m v is the mass of the suspension of the wireless remote control mobile inspection vehicle, m w is the tire mass, k w is the tire stiffness; The wireless dynamic acceleration test and analysis subsystem includes a bridge vibration component extraction module and a frequency extraction and calculation module. When 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 Afterwards, 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 road until it reaches the other end of the bridge deck and ends the measurement. The bridge vibration component extraction module receives the acceleration signals collected by each magnetoelectric vibration sensor during the driving process. For each acceleration signal collected by the magnetoelectric vibration sensor, the bridge vibration component extraction module performs variational modal 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 frequency spectrum of each component during the driving process of the corresponding mobile measuring device, and then determines the bridge vibration component spectrum according to the amplitude of the spectrum, and then extracts the corresponding bridge frequency according to the bridge vibration component spectrum. The frequency extraction and calculation module also takes the average of the three bridge frequencies extracted from the acceleration signals collected by the three magnetoelectric vibration sensors to obtain an indirect measurement result of the bridge frequency.

6. The bridge frequency indirect measurement system based on a mobile measurement device according to claim 5 is characterized in that: The preset range of the axle frequency ratio is 0.8 to 0.95 or 1.05 to 1.

2.

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

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

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