A vehicle-mounted mobile multifunctional bridge vibration signal acquisition method

Abstract

The invention relates to a vehicle-mounted mobile multifunctional bridge vibration signal acquisition method, comprising a vehicle-mounted accelerometer, a laser displacement meter, a Doppler laser vibrator, an encoder and a vehicle; the laser displacement meter and the Doppler laser vibrator are arranged at intervals on the center line of the vehicle; the vehicle-mounted accelerometer is used to measure the vertical acceleration of the vehicle itself and calculate the vertical movement speed and vertical movement reference displacement of the vehicle, and the laser displacement meter is used to obtain the distance between the vehicle and the bridge deck; the Doppler laser vibrator measures the relative speed of bridge vibration, and then calculates the relative acceleration and relative displacement of bridge vibration, and finally calculates the international flatness index of the bridge deck according to the longitudinal section elevation of the bridge deck, which can not only measure the vibration signal and bridge deck elevation of the bridge in real time, but also can be extended to the acquisition of highway pavement vibration and elevation data, and the acquisition of railway or subway track vibration and elevation data, all of which are within the protection scope of the invention.

Description

Technical Field

[0001] The invention relates to the technical field of bridge information collection, and in particular to a vehicle-mounted mobile and multifunctional bridge vibration signal collection method. Background Art

[0002] As a key node of road and rail transportation, the performance and operation safety of bridges have long been widely concerned, so the rapid detection of bridge bearing capacity and online real-time damage identification have always been a research hotspot in the industry. In particular, large bridges often need to establish a safety monitoring system to ensure the safe operation of the bridge.

[0003] In order to achieve rapid evaluation of bridge load and damage identification, it is necessary to apply dynamic and static loads to the bridge, collect its deflection and dynamic displacement, velocity and acceleration information, and use relevant algorithms to evaluate and identify bridge damage. However, most of the traditional bridge vibration signal acquisition methods are to place relevant sensors on the bridge deck and use vehicle excitation to collect vibration signals. This classic method often requires a long preparation time and interrupts traffic for a long time.

[0004] In recent years, bridge evaluation technology based on vehicle-bridge resonance has been very popular. However, many bridge evaluation methods based on vehicle-bridge resonance often use methods such as Hilbert transform to extract the vibration signal of the bridge from the vibration signal of the vehicle body. This separation technology is difficult to ensure the objectivity of the bridge vibration signal to a certain extent. In addition, when calculating the vehicle-bridge resonance model, some resonance technologies simulate the bridge deck elevation change between the vehicle and the bridge through a combination of power density spectral or simple harmonic functions of flatness. This simulation is also a large number of statistical results, which is difficult to reflect the changes in the elevation of a certain actual bridge deck. Based on this, it is necessary to study a vehicle-mounted mobile and multifunctional bridge vibration signal acquisition method. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a vehicle-mounted mobile multifunctional bridge vibration signal collection method, which effectively solves the problem that the existing bridge evaluation method of vehicle-bridge resonance is difficult to reflect the real condition of the beam bridge. Based on the above shortcomings, the present invention proposes a vehicle-mounted mobile multifunctional bridge vibration displacement, velocity, acceleration signal and bridge deck longitudinal section elevation collection method, which can realize real-time and rapid bridge structure vibration signal and bridge deck elevation testing, and is suitable for rapid detection and damage analysis of small and medium span bridges based on vehicle-bridge resonance.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a vehicle-mounted mobile multifunctional bridge vibration signal acquisition method, comprising a vehicle-mounted accelerometer, a laser displacement meter, a Doppler laser vibrator, an encoder and a vehicle; the laser displacement meter and the Doppler laser vibrator are arranged on the center line of the vehicle at intervals, and the vehicle-mounted accelerometer is located above the Doppler laser vibrator; the encoder can provide distance measurement after calibration to realize the pile number positioning of the test results of each detection equipment;

[0007] The vehicle-mounted accelerometer is used to measure the vertical acceleration a0 of the vehicle itself and calculate the vertical motion speed v of the vehicle. v And the vertical motion reference displacement dv, the formula is as follows:

[0008] v v =∫a0dt;d v =∫∫a0dt;

[0009] The laser displacement meter is used to obtain the distance d between the vehicle and the bridge deck;

[0010] The Doppler laser vibrometer measures the relative speed v of the bridge vibration br , and then calculate the relative acceleration a of the bridge vibration br and relative displacement d br , the formula is as follows;

[0011] d br =∫v br dt;

[0012] Calculate the bridge deck longitudinal section elevation H, the formula is as follows:

[0013] H=d v -dd br ;

[0014] Finally, the international roughness index of the bridge deck is calculated based on the longitudinal section elevation H of the bridge deck (the specific calculation method is supplemented).

[0015] Furthermore, a detection hole is opened on the center line, and the detection heads of the laser displacement meter and the Doppler laser vibrator are directly opposite to the detection hole; a bracket is provided on the vehicle, and the vehicle-mounted accelerometer is installed on the bracket and is directly above the Doppler laser vibrator.

[0016] Furthermore, the distance between the detection hole of the laser displacement meter and the detection hole of the Doppler laser vibrometer is D, and the vehicle is also provided with an on-board speedometer for real-time detection of the vehicle speed V. The delay time T is calculated by the real-time vehicle speed V and the distance D, and the detection points of the laser displacement meter and the Doppler laser vibrometer are matched by the delay time T.

[0017] Furthermore, the absolute velocity a and acceleration v of the bridge vibration are calculated using the following formula:

[0018] v=v br -v v , a=a br -a0.

[0019] Furthermore, the encoder adopts a photoelectric relative encoder with a pulse number of ≥1048 per circle. After calibration, it can provide distance measurement with a minimum resolution of 1mm, thereby realizing the pile number positioning of the test results of other equipment.

[0020] Furthermore, the vehicle-mounted accelerometer adopts a capacitive sensor, whose range is not less than ±2g, sensitivity is not less than 5μg, and sampling frequency is not less than 200Hz.

[0021] Furthermore, the laser displacement sensor adopts laser triangulation method, the reference distance is not less than 30cm, the measurement range is not less than ±20cm, the sampling frequency is not less than 16kHz, and the laser level is ≥2.

[0022] Furthermore, the Doppler laser vibrometer adopts the laser Doppler velocity measurement principle, with a measuring distance of not less than 40 cm, a sampling frequency of not less than 60 kHz, a velocity peak of not less than 200 mm / s, an acceleration peak of not less than 100 m2 / s, and a displacement peak of not less than 10 mm.

[0023] The beneficial effects of the above technical solution are:

[0024] The present invention proposes a vehicle-mounted mobile multifunctional bridge vibration signal acquisition method, which can realize the test of vehicle-mounted real-time bridge vibration signals. The method installs vehicle-mounted accelerometers, laser displacement meters, Doppler laser vibrometers, encoders and other equipment on operating vehicles. Among them, the accelerometer collects the vibration of the vehicle itself, and a reference speed of the vehicle can be obtained by integrating it once, and a reference displacement of the vehicle can be obtained by integrating it twice. The laser sensor measures the distance from the vehicle to the bridge deck. The Doppler laser vibrometer measures the instantaneous vibration relative velocity signal of the bridge, and the absolute speed of the bridge vibration can be obtained by removing the reference speed of the vehicle; the first-order time derivative can obtain the relative acceleration of the bridge, and the absolute acceleration of the bridge vibration can be obtained by removing the acceleration of the vehicle; the relative displacement of the bridge vibration can be obtained by integrating it once. The longitudinal elevation of the bridge deck can be obtained by subtracting the distance from the vehicle to the bridge deck from the reference displacement of the vehicle and then subtracting the relative displacement of the bridge vibration. The international roughness index (IRI) of the bridge deck can then be calculated. This method can measure the longitudinal elevation of the bridge deck (or the international roughness index IRI) and the bridge vibration displacement, velocity and acceleration signals in real time, providing basic data for vehicle-bridge resonance and bridge vibration damage analysis.

[0025] Therefore, the present invention is based on the vehicle-mounted accelerometer, laser displacement meter and Doppler laser vibrometer, and can intuitively measure the vertical acceleration, the distance between the vehicle and the bridge deck and the relative speed of the bridge vibration; then the bridge deck longitudinal section elevation is calculated by the formula, and the bridge deck longitudinal section elevation is used to calculate the international roughness index of the bridge deck; thus, from a theoretical perspective, the relationship between the vertical acceleration, the distance between the vehicle and the bridge deck, the relative speed of the bridge vibration and the international roughness index IRI is studied and determined, breaking away from the limitations of the existing research methods, with good versatility and broad application and promotion prospects. At the same time, the present invention can realize real-time and rapid bridge vibration signal and bridge deck longitudinal section elevation data acquisition, providing technical guarantee for the rapid realization of bridge rapid detection and damage identification technology based on vehicle-bridge resonance. Not only can the vibration signal and bridge deck elevation of the bridge be measured in real time, but it can also be extended to the vibration and elevation data acquisition of highway pavement, and the vibration and elevation data acquisition of railway or subway tracks, all of which are within the protection scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the present invention;

[0027] Figure 2 This is the calculation model for IRI's 1 / 4 car.

[0028] Reference numerals: 1 is a vehicle, 2 is a laser displacement meter, 3 is a Doppler laser vibrometer, 4 is a vehicle-mounted accelerometer, and 5 is an encoder. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0030] Embodiment 1, this embodiment aims to provide a method for collecting vibration displacement, velocity, acceleration signal and bridge deck longitudinal section elevation of a vehicle-mounted mobile multifunctional bridge, which can realize real-time and rapid testing of bridge structure vibration signal and bridge deck elevation, and is suitable for rapid detection and damage analysis of small and medium span bridges based on vehicle-bridge resonance.

[0031] like Figure 1 In the figure, a vehicle-mounted mobile multifunctional bridge vibration signal acquisition method includes a vehicle-mounted accelerometer 4, a laser displacement meter 2, a Doppler laser vibrator 3, an encoder 5 and a vehicle 1; the vehicle-mounted accelerometer 4, the laser displacement meter 2, the Doppler laser vibrator 3, the encoder 5 and other devices are installed on the operating vehicle 1, and these devices are integrated through a circuit system to form a data acquisition system.

[0032] In terms of specific structure, the laser displacement meter 2 and the Doppler laser vibrator 3 are arranged at intervals on the center line of the vehicle 1, the direction of the center line is the same as the shape direction of the vehicle, and a detection hole is opened on the center line, and the detection heads of the laser displacement meter and the Doppler laser vibrator are opposite to the detection hole; during implementation, a bracket can be provided on the vehicle 1, and the vehicle-mounted accelerometer 4 is installed on the bracket and is directly above the Doppler laser vibrator 3.

[0033] The distance between the detection hole of the laser displacement meter 2 and the detection hole of the Doppler laser vibrator 3 is D. The vehicle 1 is also provided with an on-board speedometer for real-time detection of the vehicle speed V. The delay time T is calculated by the real-time vehicle speed V and the distance D. The detection points of the laser displacement meter 2 and the Doppler laser vibrator 3 are matched one by one by the delay time T. For example, when the vehicle is traveling at a uniform speed, due to the existence of the distance between the detection holes, the bridge surface points measured by the laser displacement meter have hysteresis, specifically T=D / V.

[0034] During implementation, the vehicle starts and accelerates to 80km / h, then stabilizes between 70km / h and 90km / h. When the vehicle reaches the test starting point, the vehicle's acceleration information and speed information are collected through the on-board accelerometer and on-board speedometer respectively until the vehicle reaches the test end point.

[0035] Specifically, the spacing of D can be set to 10-50cm. For example, if D is 20cm and V is 80km / h, it can be calculated that the delay time T is about 0.009s. The data measured by the laser displacement meter and the data measured by the Doppler laser vibrometer are delayed by the delay time to make the distance between the vehicle and the bridge deck correspond to the relative speed of the bridge vibration, thereby ensuring the uniformity of the data at the measured points.

[0036] In this embodiment, the encoder 5 can provide distance measurement after calibration, so as to realize the pile number positioning of the test results of each detection equipment; during implementation, the encoder adopts a photoelectric relative encoder, and the number of pulses per circle is ≥1048. After calibration, it can provide distance measurement with a minimum resolution of 1mm, so as to realize the pile number positioning of the test results of other equipment.

[0037] The vehicle-mounted accelerometer uses a capacitive sensor with a range of no less than ±2g, a sensitivity of no less than 5μg, and a sampling frequency of no less than 200Hz. The vehicle-mounted accelerometer is used to measure the vertical acceleration a0 of the vehicle itself and calculate the vertical motion speed v of the vehicle. v And the vertical motion reference displacement dv, the formula is as follows:

[0038] v v =∫a0dt;d v =∫∫a0dt.

[0039] The laser displacement sensor adopts laser triangulation method, with a reference distance of not less than 30 cm, a measurement range of not less than ±20 cm, a sampling frequency of not less than 16 kHz, and a laser level ≥ 2. The laser displacement meter is used to obtain the distance d between the vehicle and the bridge deck.

[0040] The Doppler laser vibrometer adopts the laser Doppler velocity measurement principle, with a measurement distance of not less than 40 cm, a sampling frequency of not less than 60 kHz, a velocity peak of not less than 200 mm / s, an acceleration peak of not less than 100 m2 / s, and a displacement peak of not less than 10 mm; the Doppler laser vibrometer measures the relative velocity v of the bridge vibration. br , and then calculate the relative acceleration a of the bridge vibration br and relative displacement d br , the formula is as follows;

[0041] d br =∫v br dt;

[0042] Calculate the absolute velocity a and acceleration v of the bridge vibration using the following formula:

[0043] v=v br -v v , a=a br -a0.

[0044] Calculate the bridge deck longitudinal section elevation H, the formula is as follows:

[0045] H=d v -dd br .

[0046] Finally, the international smoothness index of the bridge deck is calculated based on the longitudinal section elevation H of the bridge deck.

[0047] When calculating the international roughness index of the bridge deck from the elevation of the longitudinal section of the bridge deck, first, the IRI is calculated from the longitudinal section of the road, and the sampling interval should be less than 300mm. The resolution of the elevation is determined by the flatness of the road surface. The flatter the road surface, the higher the resolution required. Generally, a resolution of 0.5mm is adopted. Secondly, it is assumed that the slope of the section between the sampling elevation points is constant. The section is smoothed by the moving average method, and the moving average length is 250mm. The section is filtered by using 1 / 4 wheel, and the 1 / 4 wheel is set according to the parameters of the golden car model, and the speed is controlled to 80km / h. Finally, the cumulative displacement value of the body suspension system is divided by the length of the longitudinal section of the road to obtain the IRI.

[0048] The IRI definition reflects the characteristics of only a single wheel track section. For systems that test multiple sections simultaneously, the IRI should be calculated separately. When testing two sections simultaneously, the sections should be averaged first, and then the data should be processed using the IRI algorithm. This analysis method is called 1 / 2 wheel simulation (HRI), and the analysis and processing of IRI is completely different from HRI.

[0049] The section elevation is obtained from a series of sampling points. Each elevation corresponds to a different position of the section. The longitudinal spacing of the sampling points is a constant Δ, which can be considered as a setting. The 1 / 4 wheel flatness index IRI is suitable for continuous sections. In this way, interpolation can be performed between the section sampling points. Commonly used sampling point interpolation methods are: A. A slope of zero represents discontinuous elevation of the section position sampling point; B. A constant slope represents linear interpolation between points; C. The continuity of the elevation and slope at the sampling point represents quadratic interpolation between points.

[0050] In order to determine the impact of the three interpolation methods on the calculation accuracy, the IRRE organization conducted an analysis. The results showed that when Δ is very small, about 50mm or less, the three interpolation methods all give the same IRI value. However, when the Δ value is increased, it is found that the calculation result of A. is too high, the result of C. is too low, and the result of B. is very correct. When the sampling interval is increased, the result of B. is also too low. Based on these conclusions, it is usually assumed that the connecting line of the cross-section sampling points is a straight line, and the sampling interval must be limited. 300mm is the most accurate, and 600mm has some deviations.

[0051] IRI includes two different filters: moving average and quarter wheel model; the moving average is set for two reasons: A. to simulate the bumpiness of high-speed vehicles; B. to reduce the sensitivity of the IRI algorithm to the sampling interval Δ. When Δ is given, the moving average smoothing filter can be defined by the sum:

[0052]

[0053] Where: h p is the section height, h ps is the smooth section height,

[0054] k=max[1,nint(L B / Δ)] (2)

[0055] Among them: the function max is the maximum value of two variables, the function nint refers to the nearest integer, L B is the moving average length, which is 250mm. For example, when the spacing Δ=150mm(6in), (L B / Δ) is 1.67, which is rounded to 2. 2 is greater than 1, so the k value is 2.

[0056] Figure 2 This is the calculation model of IRI's 1 / 4 car. The model mainly involves the dynamic response of flatness to vehicle vibration. Through analysis, the motion equation of the above model can be obtained:

[0057]

[0058]

[0059] Where mass, elastic modulus, and damping are defined as follows:

[0060] Cs is the damping of the suspension system, ks is the elastic coefficient of the suspension system, kt is the tire elastic coefficient, ms is the body mass (the body mass supported by a single wheel), and mu is the wheel mass (including the mass of the wheel, tire and half of the axle / suspension mass)

[0061] In order to simplify the equation, all parameters are based on the body mass ms. The following are the parameters of the car model:

[0062] c=c s / m s =6.0; k1 = k t / m s =653;

[0063] k2=k s / m s =63.3; μ = m u / m s =0.15

[0064] Equations (3) and (4) can be simplified to:

[0065]

[0066]

[0067] The above equation can be written as four first-order ordinary differential equations in matrix form:

[0068]

[0069] Where: x, A, and B matrices are defined as follows:

[0070]

[0071]

[0072] B=[0,0,0,k1 / μ] T (8)

[0073] x is an array of state variables.

[0074] The variables in formulas (7) and (8) are defined as follows:

[0075] h ps —Elevation of the smoothed section;

[0076] z s —The height of the vehicle body mass in the vertical direction;

[0077] z u —The vertical height of the gear train mass.

[0078] is the partial derivative with respect to time t, that is:

[0079] t=x / V (9)

[0080] Where: x is the longitudinal distance, V is the simulated vehicle forward speed. The IRI speed V is set to 80km / h (49.7mi / h). The unit of V is length / second, and the length unit is the same as the x unit.

[0081] IRI is equal to the cumulative displacement of 1 / 4 of the wheel model body mass and wheel train mass divided by the section length L:

[0082]

[0083] Before solving differential equation (7), the state parameters at the initial time should be determined or estimated. Section testing is a transition process. When the vehicle enters the test section, the impact of the initial value on it will gradually decrease. When calculating IRI, the vehicle speed is controlled at 80km / h, and the initial value affects the distance of 1 / 4 wheel about 20m. The most effective way to process the initial value is to measure 20m before the test section, and then start simulating the calculation of IRI there. It is usually recommended that the elevation data within 11m before the longitudinal section be used as the initial value.

[0084] Formulas (1) to (10) define IRI. This type of initial value problem or ordinary differential equation can be solved by the 1 / 4 car model dynamics principle and the initial value method. There are many ways to solve this type of problem, and therefore there are many ways to calculate IRI.

[0085] This embodiment uses the recommended algorithm for calculation;

[0086] When solving the linear equation (7), the total response at point i is equal to the free response at the previous point i-1 plus the forced response between point i-1 and point i. At this time, a constant is input and the result can be expressed as:

[0087] x i =e A·Δ / V x i-1 +A -1 (e A·Δ / V-I)·B·u (11)

[0088] Where: e is the base of the natural logarithm, I is a 4×4 identity matrix, and u is a constant between point i-1 and point i. A·Δ / V is a position transformation matrix, defined as the free response value of point i-1. (A -1 (e A·Δ / V -I)·B) is a four-element partial response matrix, defined as the strong approximate response value of the linear function u. The matrix exponential can be expanded through the Tailer series:

[0089]

[0090] Where N is a fairly large number so that the position transformation matrix unit is sufficiently accurate.

[0091] The accuracy of formula (12) depends on the value of u. The different interpolation methods mentioned above show that the approximation is best when the slope of the sampled section is a constant. In other words, the accuracy is highest when the constant u in formula (11) is the slope of the section. So equation (11) is the solution of differential equation (10):

[0092]

[0093] Where: s ps is the slope of the smooth section, the A matrix and the B matrix have been defined above. ps Replace h ps When , the corresponding matrix x needs to be redefined:

[0094]

[0095] Where: s s and u is the slope corresponding to the vehicle body mass and the wheel train mass.

[0096] Although the state parameters in formula (14) are different from those in formula (7), they are also applicable to the definition of IRI. In this case, slightly transform formula (10):

[0097]

[0098] Where n is the number of acquisition points in the selected segment, s s and u is the slope corresponding to the vehicle body and the wheel train;

[0099] When the spacing is 250 mm, the slope of the smooth section can be calculated by a simple difference equation:

[0100]

[0101] where k is defined in formula (2).

[0102] Therefore, this embodiment subtracts the distance from the vehicle to the bridge deck from the reference displacement of the vehicle, and then subtracts the relative displacement of the bridge vibration to obtain the longitudinal section elevation of the bridge deck, and then calculates the international roughness index (IRI) of the bridge deck; this method can measure the longitudinal section elevation of the bridge deck (or the international roughness index IRI) and the bridge vibration displacement, velocity and acceleration signals in real time on a moving vehicle, providing basic data for vehicle-bridge resonance and bridge vibration damage analysis.

[0103] This embodiment proposes a vehicle-mounted mobile multifunctional bridge vibration signal acquisition method, which can realize the test of vehicle-mounted real-time bridge vibration signal. Specifically, the vehicle-mounted accelerometer 4, laser displacement meter 2, Doppler laser vibrometer 3, encoder 5 and other equipment are installed on the operating vehicle 1, wherein the accelerometer collects the vibration of the vehicle itself, and a reference speed of the vehicle can be obtained by integrating it once, and a reference displacement of the vehicle can be obtained by integrating it twice; the laser sensor measures the real-time distance from the vehicle detection point to the bridge deck during the movement of the vehicle; the Doppler laser vibrometer measures the instantaneous vibration relative velocity signal of the bridge, and the absolute speed of the bridge vibration can be obtained by removing the reference speed of the vehicle; the first-order time derivative can obtain the relative acceleration of the bridge, and the absolute acceleration of the bridge vibration can be obtained by removing the acceleration of the vehicle; and the relative displacement of the bridge vibration can be obtained by integrating it once.

Claims

1. A vehicle-mounted mobile multifunctional bridge vibration signal acquisition method, characterized in that: It includes a vehicle-mounted accelerometer, a laser displacement meter, a Doppler laser vibrator, an encoder and a vehicle; the laser displacement meter and the Doppler laser vibrator are arranged at intervals on the center line of the vehicle, and the vehicle-mounted accelerometer is located above the Doppler laser vibrator; the encoder can provide distance measurement after calibration to realize the pile number positioning of the test results of each detection equipment; The vehicle-mounted accelerometer is used to measure the vertical acceleration a0 of the vehicle itself and calculate the vertical motion speed v of the vehicle. v And the vertical motion reference displacement dv, the formula is as follows: ； The laser displacement meter is used to obtain the distance d between the vehicle and the bridge deck; The Doppler laser vibrometer measures the relative speed v of the bridge vibration br , and then calculate the relative acceleration a of the bridge vibration br and relative displacement d br , the formula is as follows; ； Calculate the bridge deck longitudinal section elevation H, the formula is as follows: ； Finally, the international roughness index IRI of the bridge deck is calculated based on the bridge deck longitudinal section elevation H; When calculating the international roughness index of the bridge deck from the elevation of the longitudinal section of the bridge deck, first, the IRI is calculated from the longitudinal section of the road, and the sampling interval should be less than 300mm; the resolution of the elevation is determined by the flatness of the road surface. The flatter the road surface, the higher the required resolution, and a resolution of 0.5mm is adopted; secondly, it is assumed that the slope of the section between the sampling elevation points is constant; the section is smoothed using the moving average method, and the moving average length is 250mm; the section is filtered using 1 / 4 wheels, and the 1 / 4 wheels refer to the parameters of the golden car model, and the vehicle speed is controlled at 80km / h; finally, the cumulative displacement value of the vehicle body suspension system is divided by the length of the longitudinal section of the road to obtain the IRI.

2. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: A detection hole is opened on the center line, and the detection heads of the laser displacement meter and the Doppler laser vibrator are directly opposite to the detection hole; a bracket is arranged on the vehicle, and the vehicle-mounted accelerometer is installed on the bracket and is directly above the Doppler laser vibrator.

3. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: The distance between the detection hole of the laser displacement meter and the detection hole of the Doppler laser vibrometer is D. The vehicle is also provided with an on-board speedometer for real-time detection of the vehicle speed V. The delay time T is calculated by the real-time vehicle speed V and the distance D. The detection points of the laser displacement meter and the Doppler laser vibrometer are matched by the delay time T.

4. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: Calculate the absolute velocity a and acceleration v of the bridge vibration using the following formula: .

5. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: The encoder adopts a photoelectric relative encoder with the number of pulses per circle ≥1048. After calibration, it can provide distance measurement with a minimum resolution of 1mm, and realize the pile number positioning of the test results of other equipment.

6. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: The vehicle-mounted accelerometer adopts a capacitive sensor, whose measuring range is not less than ±2g, sensitivity is not less than 5μg, and sampling frequency is not less than 200Hz.

7. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: The laser displacement sensor adopts laser triangulation method, with a reference distance of not less than 30cm, a measurement range of not less than ±20cm, a sampling frequency of not less than 16kHz, and a laser level ≥2.

8. The vehicle-mounted mobile multifunctional bridge vibration signal acquisition method according to claim 1 is characterized in that: The Doppler laser vibrometer adopts the laser Doppler velocity measurement principle, with a measurement distance of not less than 40 cm, a sampling frequency of not less than 60 kHz, a velocity peak of not less than 200 mm / s, an acceleration peak of not less than 100 m2 / s, and a displacement peak of not less than 10 mm.

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