Aircraft load bridge monitoring method and monitoring system based on microwave radar

Abstract

The invention provides an aircraft load bridge monitoring method and monitoring system based on a microwave radar, and the method employs the microwave radar to monitor the dynamic displacement of an aircraft load bridge in real time, employs a video recognition technology to recognize an aircraft passing through the bridge, and carries out the comparison with flight information in an airport data system. The model, the quality and the speed of the airplane passing through the bridge are automatically confirmed; then, endowing an airplane model with the obtained airplane mass and speed, establishing an airplane-bridge coupling vibration model considering the bridge deck irregularity, and obtaining the dynamic displacement of the bridge midspan when the airplane passes through the airplane load bridge through nonlinear numerical calculation; and comparing the actually measured dynamic displacement with the theoretically calculated dynamic displacement, and judging whether the aircraft load bridge has a safety problem or not. According to the invention, automation and intellectualization of aircraft load bridge health monitoring can be realized, the efficiency of aircraft load bridge monitoring and evaluation is greatly improved, the cost is saved, and the accuracy of monitoring and evaluation is improved.

Description

Technical Field

[0001] The invention relates to the field of measurement and testing technology, and in particular to an aircraft load bridge monitoring method and a monitoring system based on microwave radar. Background Art

[0002] Aircraft load bridges can be divided into taxiway bridges and runway bridges. In airports, there may be cross-problems between aircraft operations and airport internal and external traffic, rivers, etc. Aircraft load bridges have become a commonly used structural form, mainly bearing aircraft loads to ensure the normal operation of aircraft during takeoff, landing and parking.

[0003] Aircraft load bridges are an important part of airport infrastructure. Their structural status needs to be monitored and evaluated. When their structural status is seriously degraded, early warning signals should be issued to ensure their safety and performance in real time and effectively.

[0004] The basic connotation of bridge health monitoring is to monitor and evaluate the condition of bridge structures, send out early warning signals when the bridge is under special climate and traffic conditions or when the bridge operation condition is abnormally serious, and provide a basis and guidance for bridge maintenance and management decisions.

[0005] Traditional bridge inspection relies heavily on the experience of managers and technicians, lacks scientific and systematic methods, often lacks a comprehensive grasp and understanding of the condition of the bridge, and information cannot be fed back in time. If the bridge's disease is underestimated, it is likely to miss the best time for maintenance, accelerate the process of bridge damage, and shorten the service life of the bridge. If the bridge's disease is overestimated, it will cause unnecessary waste of funds and the bridge's bearing capacity cannot be fully utilized. In addition, manual inspection is time-consuming and labor-intensive, and will become increasingly uneconomical as labor costs rise.

[0006] Since the 1960s, due to the serious degradation of bridges in developed countries, the continuous occurrence of safety accidents and the severity of the consequences of accidents, engineering and technical personnel have actively explored bridge structure monitoring. In recent years, some large bridges in my country have also been designed and installed with structural health monitoring systems, such as the Humen Bridge in Guangdong, the Dafosi Bridge in Chongqing, the Century Bridge in Haikou, the Third Nanjing Bridge, the Jiangyin Bridge and the Runyang Yangtze River Bridge, as well as the Sutong Yangtze River Bridge structural health monitoring system.

[0007] However, the existing bridge health monitoring systems at home and abroad still have shortcomings such as being unable to effectively identify traffic loads and difficult to conveniently measure bridge dynamic deflections. In addition, the existing bridge health monitoring systems are all for highway bridges, railway bridges or pedestrian bridges, and there is no health monitoring system specifically for aircraft load bridges. Aircraft load bridges still use manual regular inspection and special inspection methods, which have a low degree of automation and intelligence, are time-consuming and labor-intensive, and the inspection results are greatly affected by subjectivity. Summary of the invention

[0008] The present invention is to solve the problem of aircraft load bridge monitoring, and provides an aircraft load bridge monitoring method and monitoring system based on microwave radar. The microwave radar is used to monitor the dynamic displacement of the aircraft load bridge in real time, and the video recognition technology is used to identify the aircraft passing through the bridge, and the aircraft passing through the bridge is compared with the flight information in the airport data system to automatically confirm the model, mass and speed of the aircraft passing through the bridge; then the obtained aircraft mass and speed are assigned to the aircraft model, and an aircraft-bridge coupling vibration model considering the unevenness of the bridge deck is established, and the dynamic displacement of the bridge span when the aircraft passes through the aircraft load bridge is obtained by nonlinear numerical calculation; then the actual measured dynamic displacement is compared with the dynamic displacement obtained by theoretical calculation to determine whether there is a safety problem with the aircraft load bridge. The present invention can realize the automation and intelligence of aircraft load bridge health monitoring, greatly improve the efficiency of aircraft load bridge monitoring and evaluation, save costs, and improve the accuracy of monitoring and evaluation.

[0009] The present invention provides an aircraft load bridge monitoring method based on microwave radar, comprising the following steps:

[0010] S1. Obtain monitoring data: The microwave radar emits microwaves to the target and obtains the actual dynamic displacement of the mid-span of the aircraft-loaded bridge in real time based on the echo signal, which is output to the nonlinear numerical calculation module, and then the actual dynamic displacement curve of the mid-span is obtained; the visual recognition module obtains the aircraft model, aircraft speed and aircraft mass m based on the video of the aircraft passing over the aircraft-loaded bridge taken by the camera. 1 And output to the nonlinear numerical calculation module;

[0011] Enter steps S2, S3, and S4 respectively;

[0012] S2. Obtain aircraft load components; establish an aircraft load model by analyzing the aircraft stress conditions and obtain aircraft load components F V , proceed to step S5;

[0013] S3. Obtain bridge load vector: By discretizing the aircraft load bridge structure, the bridge load vector F is obtained. B , proceed to step S5;

[0014] S4, obtaining a bridge deck unevenness sample: simulating a road surface unevenness power spectrum S(ω) of the aircraft load bridge to obtain a road surface unevenness sample r(x), and proceeding to step S5;

[0015] S5. Bridge-machine coupling vibration analysis: According to the aircraft load component F V , bridge load vector F BThe coordination conditions of the same displacement and equal interaction force at the contact point between the aircraft wheel and the bridge deck are coupled with the road surface irregularity sample r(x), and the aircraft-bridge coupled vibration model is established to obtain the mid-span coupled dynamic displacement and mid-span coupled dynamic displacement curve of the aircraft-loaded bridge.

[0016] S6. Judgment and output of monitoring results: The nonlinear numerical calculation module compares the actual dynamic displacement in the mid-span with the coupled dynamic displacement in the mid-span and determines whether the aircraft load bridge needs to be repaired and then outputs the monitoring results;

[0017] Return to step S1 and continue monitoring.

[0018] The present invention discloses a method for monitoring bridge loads by microwave radar. As a preferred method, in step S1, the nonlinear numerical calculation module obtains the aircraft model and aircraft speed according to the aircraft video, and then obtains the aircraft flight number and aircraft mass m by comparing them with the flight information in the airport data system. 1 ;

[0019] In step S2,

[0020] Among them, M V is the mass matrix of the aircraft, Y V is the displacement vector of the aircraft, is the velocity vector of the aircraft, is the acceleration vector of the aircraft, C V is the damping matrix of the aircraft, K V is the stiffness matrix of the aircraft;

[0021] In step S3,

[0022] Among them, M B is the mass matrix of the aircraft load bridge, Y B is the displacement vector of the bridge due to aircraft load, is the velocity vector of the aircraft loading the bridge, is the acceleration vector of the aircraft load bridge, C B is the damping matrix of the aircraft load bridge, K B is the stiffness matrix of the bridge subjected to aircraft loads.

[0023] The aircraft load bridge monitoring method based on microwave radar described in the present invention is, as a preferred embodiment, in step S2,

[0024]

[0025] Y V =[y 1 y 2 y 3y 4 ] T ;

[0026] Among them, m 2 is the mass of the rear wheel, m 3 is the mass of the front wheel, J is the moment of inertia, l 1 is the horizontal distance from the rear wheel to the center of mass of the aircraft, l 2 is the horizontal distance from the front wheel to the center of mass of the aircraft, l is the wheelbase of the rear wheel, k 1 is the stiffness coefficient of the interaction between the rear wheel and the bridge deck, k 2 is the stiffness coefficient of the connection between the aircraft body and the rear wheel, k 3 is the stiffness coefficient of the connection between the aircraft body and the front wheel, k 4 is the stiffness coefficient of the interaction between the front wheel and the bridge deck, c 1 is the damping coefficient of the interaction between the rear wheel and the bridge deck, c 2 is the damping coefficient of the connection between the aircraft body and the rear wheel, c 3 is the damping coefficient of the connection between the aircraft body and the front wheel, c 4 is the damping coefficient of the interaction between the front wheel and the bridge deck, y 1 is the vertical displacement of the rear wheel, y 2 is the vertical displacement at the rear end of the fuselage and above the rear wheel, y 3 is the vertical displacement of the front end of the fuselage and above the front wheel, y 4 is the vertical displacement of the front wheel.

[0027] The aircraft load bridge monitoring method based on microwave radar described in the present invention is preferably configured such that in step S3, the damping matrix C of the aircraft load bridge is B Rayleigh damping is used and external load damping is zero;

[0028] C B =α 0 M+β 0 K;

[0029] Among them, α 0 =2ε 1 ω 01 -β 0 ω 01 ω 01 ;

[0030] ω 01 ,ω 02 are the first order natural frequency and the second order natural frequency of the structure, ∈ 1 ,∈ 2 are the first and second modal damping of the structure respectively, M is the mass matrix, and K is the stiffness matrix.

[0031] The aircraft load bridge monitoring method based on microwave radar described in the present invention is, as a preferred embodiment, in step S4,

[0032] Among them, ω 0 is the reference spatial frequency, ω 0 0.1m- 1 , ω is the spatial frequency, S is the power spectrum density value at the reference spatial frequency, and β is a coefficient proportional to the stiffness;

[0033] The road surface roughness sample r(x) is obtained by using triangular series superposition method, quadratic filtering method, AR model method and ARMA model method;

[0034] In step S5, the coupled vibration equation of the aircraft-bridge coupled vibration model is:

[0035]

[0036] Among them, f i (t) is the interaction force between the i-th wheel and the aircraft load bridge deck, k i is the stiffness corresponding to the i-th row of the bridge deck stiffness matrix K, c i is the bridge deck irregularity damping coefficient corresponding to the i-th wheel, is the vertical acceleration of the i-th wheel relative to the bridge deck at time t, Δ i (t) is the vertical displacement of the i-th wheel relative to the bridge deck at time t, y i is the vertical displacement of the i-th wheel at time t, z i is the vertical displacement of the bridge deck at the contact point between the i-th wheel and the bridge deck at time t, r i The sample value of the bridge deck irregularity at the i-th wheel-bridge contact point.

[0037] The aircraft load bridge monitoring method based on microwave radar described in the present invention is, as a preferred embodiment, in step S4, a road surface unevenness sample r(x) is simulated by a trigonometric series superposition method;

[0038]

[0039] Among them, α k is the amplitude of the cosine function, ω k For the power spectrum density defined interval [ω l ,ω u ], θ k is a random phase angle uniformly distributed between 0 and 2π, x is the local coordinate, x is the distance from a point on the bridge to the left end of the bridge, and N is the number of points simulating random irregularities. S is the power spectral density function in the interval [ω l ,ω u] is defined as a function of the spatial frequency of road surface irregularity;

[0040]

[0041] Among them, α is the roughness coefficient and β is the exponent.

[0042] The aircraft load bridge monitoring method based on microwave radar described in the present invention is preferably implemented in step S5.

[0043] The coupled vibration equations can be solved by the linear acceleration method, New-mark-β method or Wilson-0 method.

[0044] The aircraft-loaded bridge monitoring method based on microwave radar described in the present invention is, as a preferred embodiment, in step S6, the standard for judging whether the aircraft-loaded bridge needs to be repaired is: when the peak value of the actual dynamic displacement curve at the mid-span is 10% higher than the peak value of the mid-span coupled dynamic displacement curve, or the time integral of the actual dynamic displacement curve at the mid-span is 20% higher than the time integral of the mid-span coupled dynamic displacement curve, the aircraft-loaded bridge has a safety problem and needs to be repaired.

[0045] The present invention provides an aircraft load bridge monitoring system based on microwave radar, comprising a microwave radar arranged on a pier or abutment of the aircraft load bridge, a target arranged on the bottom surface of the mid-span of the aircraft load bridge, a camera arranged on one side of the aircraft load bridge, and a control processing system electrically connected to the microwave radar and the camera;

[0046] The microwave radar is used to emit microwaves to the target and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the control processing system to form an actual mid-span dynamic displacement curve. The camera is used to observe the aircraft passing over the aircraft-loaded bridge and output the video to the control processing system. The control processing system is used to analyze the video and identify the aircraft model and aircraft speed. The control processing system is used to compare the identified aircraft model and aircraft speed with the flight information in the airport data system to obtain the aircraft flight number and aircraft mass. The control processing system is used to obtain the mid-span coupled dynamic displacement and the mid-span coupled dynamic displacement curve of the aircraft-loaded bridge according to the aircraft speed and aircraft mass. The control processing system is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs maintenance.

[0047] The aircraft load bridge monitoring system based on microwave radar described in the present invention, as a preferred embodiment, the control processing system includes an electrically connected visual recognition module and a nonlinear numerical calculation module, the visual recognition module is electrically connected to the camera and the airport data system, and the nonlinear numerical calculation module is electrically connected to the microwave radar and the target;

[0048] The microwave radar is used to emit microwaves to the target and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the nonlinear numerical calculation module to form an actual mid-span dynamic displacement curve. The camera is used to observe the aircraft passing over the aircraft-loaded bridge and output the video to the visual recognition module. The visual recognition module is used to analyze the video and identify the aircraft model and aircraft speed and obtain the aircraft flight number and aircraft mass according to the flight information in the airport data system and output them to the nonlinear numerical calculation module. The nonlinear numerical calculation module is used to obtain the mid-span coupled dynamic displacement and the mid-span coupled dynamic displacement curve of the aircraft-loaded bridge according to the aircraft speed and aircraft mass. The nonlinear numerical calculation module is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs maintenance.

[0049] The present invention has the following advantages:

[0050] The present invention provides a health monitoring system that can be used for aircraft-loaded bridges. The microwave radar technology and video recognition technology are applied to the health monitoring system of aircraft-loaded bridges. The dynamic displacement of aircraft-loaded bridges is monitored in real time by microwave radar, and the aircraft passing through the bridge is identified by video recognition technology, and the aircraft passing through the bridge is compared with the flight information in the airport data system to automatically confirm the model, mass and speed of the aircraft passing through the bridge; then the obtained aircraft mass and speed are assigned to the aircraft model, and an aircraft-bridge coupling vibration model considering the unevenness of the bridge deck is established. The dynamic displacement of the bridge span when the aircraft passes through the aircraft-loaded bridge is obtained by nonlinear numerical calculation; then the actual measured dynamic displacement is compared with the dynamic displacement obtained by theoretical calculation to determine whether the aircraft-loaded bridge has safety problems. The present invention can realize the automation and intelligence of aircraft-loaded bridge health monitoring, greatly improve the efficiency of aircraft-loaded bridge monitoring and evaluation, save costs, and improve the accuracy of monitoring and evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a flow chart of a method for monitoring bridges under aircraft loads based on microwave radar;

[0052] Figure 2 An aircraft model diagram of an aircraft load bridge monitoring method based on microwave radar;

[0053] Figure 3 A schematic diagram of a simulated sample of road surface irregularity in a microwave radar-based aircraft load bridge monitoring method;

[0054] Figure 4 The present invention is a schematic diagram of a monitoring method for aircraft load bridges based on microwave radar and a monitoring system structure;

[0055] Figure 5 A bridge monitoring method for aircraft loads based on microwave radar. Dynamic displacement diagram of the bridge mid-span.

[0056] Reference numerals:

[0057] 1. Microwave radar; 2. Target; 3. Camera; 4. Control and processing system; 41. Visual recognition module; 42. Nonlinear numerical calculation module. DETAILED DESCRIPTION

[0058] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0059] Example 1

[0060] like Figure 1 As shown, a method for monitoring bridges under aircraft load based on microwave radar comprises the following steps:

[0061] S1. Obtain monitoring data: The microwave radar 1 transmits microwaves to the target 2 and obtains the actual dynamic displacement of the mid-span of the aircraft-loaded bridge in real time according to the echo signal, which is output to the nonlinear numerical calculation module 42, and then the actual dynamic displacement curve of the mid-span is obtained; the visual recognition module 41 obtains the aircraft model, aircraft speed and aircraft mass m according to the aircraft video taken by the camera 3 passing through the aircraft-loaded bridge 1 And output to the nonlinear numerical calculation module 42;

[0062] The nonlinear numerical calculation module 42 obtains the aircraft model and aircraft speed according to the aircraft video, and then obtains the aircraft flight number and aircraft mass m by comparing with the flight information in the airport data system. 1 ;

[0063] Enter steps S2, S3, and S4 respectively;

[0064] S2. Obtain aircraft load components; establish an aircraft load model by analyzing the aircraft stress conditions and obtain aircraft load components F V ;

[0065]

[0066] Among them, M V is the mass matrix of the aircraft, Y V is the displacement vector of the aircraft, is the velocity vector of the aircraft, is the acceleration vector of the aircraft, C V is the damping matrix of the aircraft, K V is the stiffness matrix of the aircraft;

[0067]

[0068] YV =[y 1 y 2 y 3 y 4 ] T .

[0069] Among them, m 2 is the mass of the rear wheel, m 3 is the mass of the front wheel, J is the moment of inertia, l 1 is the horizontal distance from the rear wheel to the center of mass of the aircraft, l 2 is the horizontal distance from the front wheel to the center of mass of the aircraft, l is the wheelbase of the rear wheel, k 1 is the stiffness coefficient of the interaction between the rear wheel and the bridge deck, k 2 is the stiffness coefficient of the connection between the aircraft body and the rear wheel, k 3 is the stiffness coefficient of the connection between the aircraft body and the front wheel, k 4 is the stiffness coefficient of the interaction between the front wheel and the bridge deck, c 1 is the damping coefficient of the interaction between the rear wheel and the bridge deck, c 2 is the damping coefficient of the connection between the aircraft body and the rear wheel, c 3 is the damping coefficient of the connection between the aircraft body and the front wheel, c 4 is the damping coefficient of the interaction between the front wheel and the bridge deck, y 1 is the vertical displacement of the rear wheel, y 2 is the vertical displacement at the rear end of the fuselage and above the rear wheel, y 3 is the vertical displacement of the front end of the fuselage and above the front wheel, y 4 is the vertical displacement of the front wheel;

[0070] Go to step S5;

[0071] S3. Obtain bridge load vector: By discretizing the aircraft load bridge structure, the bridge load vector F is obtained. B ,

[0072]

[0073] Among them, M B is the mass matrix of the aircraft load bridge, Y B is the displacement vector of the bridge due to aircraft load, is the velocity vector of the aircraft loading the bridge, is the acceleration vector of the aircraft load bridge, C B is the damping matrix of the aircraft load bridge, K B is the stiffness matrix of the bridge under aircraft load;

[0074] Damping matrix C of aircraft loaded bridge B Rayleigh damping is used and external load damping is zero;

[0075] C B =α 0 M+β 0 K;

[0076] Among them, α 0 =2ε 1 ω 01 -β 0 ω 01 ω 01 ;

[0077] ω 01 ,ω 02 are the first order natural frequency and the second order natural frequency of the structure, ∈ 1 ,∈ 2 are the first-order modal damping and the second-order modal damping of the structure respectively, M is the mass matrix, and K is the stiffness matrix;

[0078] Go to step S5;

[0079] S4. Obtaining bridge deck unevenness samples: According to the power spectrum S(ω) of the bridge under aircraft load, the road surface unevenness samples r(x) are simulated.

[0080]

[0081] Among them, ω 0 is the reference spatial frequency, ω 0 0.1m -1 , ω is the spatial frequency, Sω 0 is the power spectral density value at the reference spatial frequency, β is a coefficient proportional to the stiffness;

[0082] The road surface roughness sample r(x) is obtained by using triangular series superposition method, quadratic filtering method, AR model method and ARMA model method;

[0083] The road surface roughness sample r(x) is simulated by the trigonometric series superposition method;

[0084]

[0085] Among them, α k is the amplitude of the cosine function, ω k For the power spectrum density defined interval [ω l ,ω u ], θ k is a random phase angle uniformly distributed between 0 and 2π, x is the local coordinate, x is the distance from a point on the bridge to the left end of the bridge, and N is the number of points simulating random irregularities. k The power spectral density function is in the interval [ωl ,ω u ] is defined as a function of the spatial frequency of road surface irregularity;

[0086]

[0087] Among them, α is the roughness coefficient, β is the exponent;

[0088] Go to step S5;

[0089] S5. Bridge-machine coupling vibration analysis: According to the aircraft load component F V , bridge load vector F B The coordination conditions of the same displacement and equal interaction force at the contact point between the aircraft wheel and the bridge deck are coupled with the road surface irregularity sample r(x), and the aircraft-bridge coupled vibration model is established to obtain the mid-span coupled dynamic displacement and mid-span coupled dynamic displacement curve of the aircraft-loaded bridge.

[0090] The coupled vibration equation of the aircraft-bridge coupled vibration model is:

[0091]

[0092] Among them, f i (t) is the interaction force between the i-th wheel and the aircraft load bridge deck, k i is the stiffness corresponding to the i-th row of the bridge deck stiffness matrix K, c i is the bridge deck irregularity damping coefficient corresponding to the i-th wheel, is the vertical acceleration of the i-th wheel relative to the bridge deck at time t, Δ i (t) is the vertical displacement of the i-th wheel relative to the bridge deck at time t, y i t is the vertical displacement of the i-th wheel at time t, z i t is the vertical displacement of the bridge deck at the contact point between the i-th wheel and the bridge deck at time t, r i The sample value of bridge deck irregularity at the contact point between the i-th wheel and the bridge deck;

[0093] The coupled vibration equations are solved by the linear acceleration method, New-mark-β method, and Wilson-0 method;

[0094] S6. Determination and output of monitoring results: the nonlinear numerical calculation module 42 compares the actual dynamic displacement in the mid-span with the coupled dynamic displacement in the mid-span and determines whether the aircraft load bridge needs to be repaired and then outputs the monitoring results;

[0095] The criteria for judging whether an aircraft-loaded bridge needs maintenance are as follows: when the peak value of the actual dynamic displacement curve at the mid-span is 10% higher than the peak value of the mid-span coupled dynamic displacement curve, or the time integral of the actual dynamic displacement curve at the mid-span is 20% higher than the time integral of the mid-span coupled dynamic displacement curve, the aircraft-loaded bridge has safety problems and needs maintenance.

[0096] Return to step S1 and continue monitoring.

[0097] Example 2

[0098] like Figure 1 As shown, a method for monitoring bridges with aircraft loads based on microwave radar;

[0099] Simplify the aircraft as Figure 2 The aircraft model is shown. The fuselage is simplified as a 1 , a rigid body with a moment of inertia J about its center of mass, the distance between the two axes is l, and the masses of the wheels are m 2 and m 3 The interaction between the wheel and the ground and the connection between the body and the wheel are simulated by a spring damping system. The stiffness coefficient and damping coefficient of the interaction between the wheel and the bridge deck are k 1 、c 1 and k 4 、c 4 The stiffness and damping coefficient of the connection between the fuselage and the wheel are k 2 、c 2 and k 3 、c 3 The model has 8 degrees of freedom, namely the vertical displacement y of the wheel 1 ,y 4 , displacement z at the contact point between the wheel and the bridge deck 1 、z 2 , the vertical displacement y at both ends of the body 2 ,y 3 , displacement and rotation angle y at the center of mass of the body c ,θ. Among them z 1 、z 2 Coupled with the bridge deck displacement, y c ,θ As in formula (2-1), y 3 ,y 4 express:

[0100]

[0101] Therefore, the model has four independent degrees of freedom, and its displacement vector can be written as:

[0102] Y V =[y 1 y 2 y 3 y4 ] Y (2-2) The force analysis of each rigid body in the aircraft model is carried out, and the vibration equation of the aircraft can be listed according to the D'Alembert principle:

[0103]

[0104]

[0105] The above formula is the equilibrium formula of four degrees of freedom, f 1 ,f 2 ,f 3 ,f 4 are the magnitudes of the forces on the four degrees of freedom respectively.

[0106] To facilitate programming, the equation is organized into a matrix form:

[0107] in,

[0108]

[0109] It can be seen from the load vector on the right side of equation (2-4) that the load on the aircraft includes the elastic force and damping force caused by the deformation of the bridge. This load component couples the aircraft vibration equation with the bridge structure vibration equation to form a coupled vibration system.

[0110] (2) Bridge model

[0111] The bridge structure is discretized. After discretization, the bridge dynamic equation can be written as:

[0112]

[0113] in, are the acceleration, velocity and displacement vector of the bridge structure respectively. B is the mass matrix of the bridge structure, C B is the damping matrix of the bridge structure, K B is the stiffness matrix of the bridge structure. B It is the load vector of the bridge structure, which includes two parts: one is the force on the structure from the external environment (such as wind load, rain load, etc.), and the other is the node force on the bridge deck node from the aircraft. In this project, the external load is 0.

[0114] c=α 0 M+β 0 K (2-6)

[0115] The bridge structure adopts Rayleigh damping. As shown in formula (2-6), the damping matrix of the structure is composed of α 0 , β 0The two parameters and the stiffness matrix K and mass matrix M of the structure are defined. 0 , β 0 It can be obtained from formula (2-7) and (2-8):

[0116]

[0117] α 0 =2ε 1 ω 01 -β 0 ω 01 ω 01 (2-8)

[0118] Among them, ω 01 ,ω 02 are the first and second order natural frequencies of the structure respectively. 1 ,∈ 2 are the first and second order modal damping of the structure, respectively.

[0119] (3) Bridge deck roughness model

[0120] The unevenness of the road surface on the bridge will excite the aircraft in motion, thereby changing the vibration state of the aircraft and causing random changes in the wheel pressure load. This effect cannot be ignored in the coupled vibration of the machine bridge. Therefore, the effect of road surface unevenness should be considered in the coupled vibration analysis of the machine bridge. According to the research results of relevant literature, the unevenness of the road surface on the bridge can be described as a random process with a zero mean and a steady-state Gauss distribution. The statistical characteristics of this random process can be described by the power spectrum:

[0121]

[0122] In the formula, ω 0 is the reference spatial frequency, take 0.1m -1 , ω is the spatial frequency, S(ω 0 ) is the power spectral density value at the reference spatial frequency.

[0123] After the power spectrum of road surface roughness is given, the road surface roughness samples can generally be simulated by using a variety of methods such as triangular series superposition method, quadratic filtering method, AR model method or ARMA model method. The triangular series superposition method is used to simulate road surface roughness as follows:

[0124]

[0125] Δω=(ω u -ω l ) / N (2-13)

[0126] Among them, r(x) is the sample function of road surface roughness, α k is the amplitude of the cosine function, ωk is located in the power spectrum density definition interval [ω l ,ω u ] within the frequency range. k is a random phase angle uniformly distributed between 0 and 2π, x is a local coordinate, indicating the distance from a point on the bridge to the left end of the bridge, and N is the number of points simulating random irregularities. k )The power spectral density function is in the interval [ω l ,ω u ] is defined as a function of the spatial frequency of road surface irregularity:

[0127]

[0128] Among them, α is the roughness coefficient and the exponent β is 1.94.

[0129] The road surface roughness sample generation program RP (Roadway Profile) is compiled using the triangular series superposition method. Figure 3 The program is used to simulate and generate the sample curves of grade 1, grade 3 and grade 5 bridge road surface roughness, which correspond to the three levels of very good, average and very poor bridge road surface roughness conditions respectively.

[0130] (4) Numerical analysis of machine-bridge coupled vibration considering bridge deck irregularities

[0131] Assume that the aircraft is in constant contact with the bridge deck during its travel. The interaction force between the aircraft wheel and the bridge deck can be expressed as:

[0132]

[0133] In the formula, f i (t) is the interaction force between the i-th wheel and the bridge deck, k i is the stiffness corresponding to the i-th row of the bridge deck stiffness matrix K, c i is the bridge deck irregularity damping coefficient corresponding to the i-th wheel, and the subscript i represents the contact point between the i-th wheel and the bridge deck. is the vertical acceleration of the i-th wheel relative to the bridge deck at time t, Δ i (t) is the vertical displacement of the i-th wheel relative to the bridge deck at time t, and its expression is:

[0134] Δ i (t) = y i (t)-z i (t)-r i

[0135] In the formula, y i (t) is the vertical displacement of the i-th wheel at time t, z i (t) is the vertical displacement of the bridge deck at the contact point between the i-th wheel and the bridge deck at time t, r iThe sample value of the bridge deck irregularity at the i-th wheel-bridge contact point.

[0136] The aircraft vibration equation and the taxiway bridge equation are combined through the displacement of the contact point to establish the aircraft-taxiway bridge coupled vibration equation considering the road surface roughness.

[0137]

[0138] As two subsystems, the dynamic equations of the aircraft and the bridge are coupled through the coordination conditions of the same displacement and equal magnitude of the interaction force at the contact point between the wheel and the bridge deck. Since the interaction force between the aircraft and the bridge is related to the motion state of the aircraft and the deformation of the bridge, it is necessary to iteratively solve these two sets of coupled time-varying second-order differential equations.

[0139] Obviously, the matrix equation is a time-varying equation. As the position of the rounds changes, the external load will also change. Therefore, it needs to be solved by the step-by-step integration method.

[0140] There are three main methods of step-by-step integration: linear acceleration method, New-mark-β method and Wilson-0 method. In the whole process, the imbalance of internal forces in each time period is ignored, the initial time-varying characteristics are described at each time node, and the velocity and displacement of the seven points are used as the initial state of the next time period. Finally, the time history curve of the entire system is gradually obtained.

[0141] Example 3

[0142] like Figure 4 As shown, a microwave radar-based aircraft load bridge monitoring system includes a microwave radar 1 arranged on a pier or abutment of the aircraft load bridge, a target 2 arranged on the bottom surface of the mid-span of the aircraft load bridge, a camera 3 arranged on one side of the aircraft load bridge, and a control processing system 4 electrically connected to the microwave radar 1 and the camera 3;

[0143] The microwave radar 1 is used to emit microwaves to the target 2 and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the control processing system 4 to form an actual mid-span dynamic displacement curve. The camera 3 is used to observe the aircraft passing through the aircraft-loaded bridge and output the video to the control processing system 4. The control processing system 4 is used to analyze the video and identify the aircraft model and aircraft speed. The control processing system 4 is used to compare the identified aircraft model and aircraft speed with the flight information in the airport data system to obtain the aircraft flight number and aircraft mass. The control processing system 4 is used to obtain the mid-span coupled dynamic displacement and the mid-span coupled dynamic displacement curve of the aircraft-loaded bridge according to the aircraft speed and aircraft mass. The control processing system 4 is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs to be repaired;

[0144] The control processing system 4 includes a visual recognition module 41 and a nonlinear numerical calculation module 42 which are electrically connected. The visual recognition module 41 is electrically connected to the camera 3 and the airport data system, and the nonlinear numerical calculation module 42 is electrically connected to the microwave radar 1 and the target 2.

[0145] The microwave radar 1 is used to emit microwaves to the target 2 and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the nonlinear numerical calculation module 42 to form an actual mid-span dynamic displacement curve. The camera 3 is used to observe the aircraft passing through the aircraft-loaded bridge and output the video to the visual recognition module 41. The visual recognition module 41 is used to analyze the video and identify the aircraft model and aircraft speed and obtain the aircraft flight number and aircraft mass according to the flight information in the airport data system and output them to the nonlinear numerical calculation module 42. The nonlinear numerical calculation module 42 is used to obtain the mid-span coupled dynamic displacement and the mid-span coupled dynamic displacement curve of the aircraft-loaded bridge according to the aircraft speed and aircraft mass. The nonlinear numerical calculation module 42 is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs maintenance.

[0146] Example 4

[0147] like Figures 4-5 As shown, an aircraft load bridge monitoring system based on microwave radar is composed of a microwave radar 1, a target 2, a camera 3, and a control processing system 4. The control processing system 4 includes a data line, a computer and a software system. The software system includes an electrically connected visual recognition module 41 and a nonlinear numerical calculation module 42;

[0148] The microwave radar 1 is installed on the pier or abutment of the aircraft-loaded bridge; the target 2 is hung on the bottom surface of the bridge in the middle of the span; the camera 3 is installed near the bridge and can observe the aircraft passing over the bridge in real time; the data cable connects the microwave radar 1 and the camera 3 to the computer; the software system is installed in the computer and is responsible for processing the radar and video data and performing structural calculations.

[0149] Aircraft load bridges, aircraft operating on them and radar, targets, camera structures such as Figure 4 As shown;

[0150] The microwave radar 1 emits microwaves to the target 2 in real time, and the dynamic displacement of the bridge mid-span under the aircraft load can be obtained in real time through the echo signal, and the dynamic displacement data of the bridge mid-span can be transmitted to the control processing system 4 through the data line. Figure 5 shown.

[0151] Example 5

[0152] like Figure 4 As shown, an aircraft load bridge monitoring system based on microwave radar includes the following components:

[0153] 1. Microwave radar: installed on the piers or abutments of aircraft-loaded bridges, it is used to transmit microwaves to the bottom surface of the bridge in the middle of the span and receive the reflected microwave signals. By analyzing these echo signals, it can monitor the dynamic displacement of the bridge in the middle of the span in real time.

[0154] 2. Target: Fixed on the bottom surface of the aircraft load bridge span, it serves as a reflection target for microwave radar to transmit microwaves to ensure accurate reception of signals.

[0155] 3. Camera: Installed at a suitable location near the bridge, it can clearly observe and record aircraft passing over the bridge and capture the image information of the aircraft.

[0156] 4. Control and processing system: It consists of the following two main modules: Visual recognition module: It is electrically connected to the camera and the airport data system, responsible for receiving the video data transmitted by the camera, analyzing the video content to identify the model and speed of the aircraft, and comparing this information with the flight information in the airport data system to determine the flight number and quality of the aircraft.

[0157] Nonlinear numerical calculation module: It is electrically connected to the microwave radar and the target, receives the mid-span dynamic displacement data from the microwave radar, combines it with the aircraft information provided by the visual recognition module, and uses the nonlinear numerical calculation method to calculate the mid-span coupled dynamic displacement of the bridge under the aircraft load and the corresponding displacement curve.

[0158] The control and processing system integrates the actual dynamic displacement data and the coupled dynamic displacement data to evaluate the health of the bridge and determine whether maintenance is needed. In addition, the control and processing system also includes computer hardware and corresponding software systems for data storage and processing to ensure the accuracy of the data and the efficient operation of the system.

[0159] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for monitoring aircraft-loaded bridges based on microwave radar, characterized in that: The following steps are involved: S1, obtaining monitoring data: the microwave radar (1) emits microwaves to the target (2) and obtains the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time according to the echo signal, outputs it to the nonlinear numerical calculation module (42), and then obtains the actual mid-span dynamic displacement curve; The visual recognition module (41) obtains the aircraft model, aircraft speed and aircraft mass m1 based on the video of the aircraft passing over the aircraft load bridge shot by the camera (3) and outputs the obtained information to the nonlinear numerical calculation module (42); Enter steps S2, S3, and S4 respectively; S2. Obtain aircraft load components; establish an aircraft load model by analyzing the aircraft stress conditions and obtain aircraft load components F V , proceed to step S5; S3. Obtain bridge load vector: By discretizing the aircraft load bridge structure, the bridge load vector F is obtained. B , proceed to step S5; S4, obtaining a bridge deck unevenness sample: simulating a road surface unevenness power spectrum S(ω) of the aircraft load bridge to obtain a road surface unevenness sample r(x), and proceeding to step S5; S5. Bridge-machine coupling vibration analysis: According to the aircraft load component F V , the bridge load vector F B The uneven road surface sample r(x) is coupled with the coordination conditions of the same displacement and equal magnitude of interaction force at the contact point between the aircraft wheel and the bridge deck, an aircraft-bridge coupled vibration model is established, and the mid-span coupled dynamic displacement and mid-span coupled dynamic displacement curve of the aircraft-loaded bridge are obtained; S6, judging and outputting the monitoring results: the nonlinear numerical calculation module (42) compares the actual dynamic displacement in the mid-span with the coupled dynamic displacement in the mid-span and judges whether the aircraft load bridge needs to be repaired and then outputs the monitoring results; Return to step S1 and continue monitoring.

2. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 1, characterized in that: In step S1, the nonlinear numerical calculation module (42) obtains the aircraft model and the aircraft speed according to the aircraft video, and then obtains the aircraft flight number and the aircraft mass m1 by comparing with the flight information in the airport data system; In step S2, Among them, M V is the mass matrix of the aircraft, Y V is the displacement vector of the aircraft, is the velocity vector of the aircraft, is the acceleration vector of the aircraft, C V is the damping matrix of the aircraft, K V is the stiffness matrix of the aircraft; In step S3, Among them, M B is the mass matrix of the aircraft load bridge, Y B is the displacement vector of the bridge due to aircraft load, is the velocity vector of the aircraft loading the bridge, is the acceleration vector of the aircraft load bridge, C B is the damping matrix of the aircraft load bridge, K B is the stiffness matrix of the bridge subjected to aircraft loads.

3. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 2 is characterized in that: In step S2, <h2 style=";text-align:left;direction:ltr">Y<h2 style=";text-align:left;direction:ltr"> V <h2 style=";text-align:left;direction:ltr"> (y1 y2 y3 y4)<h2 style=";text-align:left;direction:ltr"> T <h2 style=";text-align:left;direction:ltr"> ; Wherein, m2 is the mass of the rear wheel, m3 is the mass of the front wheel, J is the moment of inertia, l1 is the horizontal distance from the rear wheel to the center of mass of the aircraft, l2 is the horizontal distance from the front wheel to the center of mass of the aircraft, l is the wheelbase of the rear wheel, k1 is the stiffness coefficient of the interaction between the rear wheel and the bridge deck, k2 is the stiffness coefficient of the connection between the aircraft body and the rear wheel, k3 is the stiffness coefficient of the connection between the aircraft body and the front wheel, k4 is the stiffness coefficient of the interaction between the front wheel and the bridge deck, c1 is the damping coefficient of the interaction between the rear wheel and the bridge deck, c2 is the damping coefficient of the connection between the aircraft body and the rear wheel, c3 is the damping coefficient of the connection between the aircraft body and the front wheel, c4 is the damping coefficient of the interaction between the front wheel and the bridge deck, y1 is the vertical displacement of the rear wheel, y2 is the vertical displacement at the rear end of the body and above the rear wheel, y3 is the vertical displacement at the front end of the body and above the front wheel, and y4 is the vertical displacement of the front wheel.

4. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 2 is characterized in that: In step S3, the damping matrix C of the aircraft load bridge B Rayleigh damping is used and external load damping is zero; C B =α0M+β0K; Among them, α0=2ε1ω 01 -b0ω 01 oh 01 ; ω 01 ,ω 02 are the first-order natural frequency and the second-order natural frequency of the structure, ∈1 and ∈2 are the first-order modal damping and the second-order modal damping of the structure, M is the mass matrix, and K is the stiffness matrix.

5. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 1, characterized in that: In step S4, Among them, ω0 is the reference spatial frequency, ω0 is 0.1m -1 , ω is the spatial frequency, S(ω0) is the power spectrum density value at the reference spatial frequency, and β is a coefficient proportional to the stiffness; The road surface irregularity sample r(x) is obtained by using the triangular series superposition method, the secondary filtering method, the AR model method and the ARMA model method; In step S5, the coupled vibration equation of the aircraft-bridge coupled vibration model is: Among them, f i (t) is the interaction force between the i-th wheel and the bridge deck of the aircraft load bridge, k i is the stiffness corresponding to the i-th row of the bridge deck stiffness matrix K, c i is the bridge deck irregularity damping coefficient corresponding to the i-th wheel, is the vertical acceleration of the i-th wheel relative to the bridge deck at time t, Δ i (t) is the vertical displacement of the i-th wheel relative to the bridge deck at time t, y i (t) is the vertical displacement of the i-th wheel at time t, z i (t) is the vertical displacement of the bridge deck at the contact point between the i-th wheel and the bridge deck at time t, r i The sample value of the bridge deck irregularity at the i-th wheel-bridge contact point.

6. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 5 is characterized by: In step S4, the road surface irregularity sample r(x) is simulated by a trigonometric series superposition method; Among them, α k is the amplitude of the cosine function, ω k For the power spectrum density defined interval [ω l ,ω u ], θ k is a random phase angle uniformly distributed between 0 and 2π, x is the local coordinate, x is the distance from a point on the bridge to the left end of the bridge, and N is the number of points simulating random irregularities. k )The power spectral density function is in the interval [ω l ,ω u ] is defined as a function of the spatial frequency of road surface irregularity; Among them, α is the roughness coefficient and β is the exponent.

7. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 5 is characterized by: In step S5, The coupled vibration equations are solved by the linear acceleration method, the New-mark-β method and the Wilson-0 method.

8. The method for monitoring bridges loaded by aircraft based on microwave radar according to claim 1, characterized in that: In step S6, the standard for judging whether the aircraft-loaded bridge needs maintenance is: when the peak value of the actual dynamic displacement curve at the mid-span is 10% higher than the peak value of the mid-span coupled dynamic displacement curve, or the time integral of the actual dynamic displacement curve at the mid-span is 20% higher than the time integral of the mid-span coupled dynamic displacement curve, the aircraft-loaded bridge has a safety problem and needs maintenance.

9. The aircraft load bridge monitoring system based on microwave radar according to any one of claims 1 to 8, characterized in that: It comprises a microwave radar (1) arranged on a pier or abutment of an aircraft-loaded bridge, a target (2) arranged on the bottom surface of the mid-span of the aircraft-loaded bridge, a camera (3) arranged on one side of the aircraft-loaded bridge, and a control processing system (4) electrically connected to the microwave radar (1) and the camera (3); The microwave radar (1) is used to emit microwaves to the target (2) and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the control processing system (4) to form an actual mid-span dynamic displacement curve. The camera (3) is used to observe the aircraft passing through the aircraft-loaded bridge and output the video to the control processing system (4). The control processing system (4) is used to analyze the video and identify the aircraft model and aircraft speed. The control processing system (4) is used to compare the identified aircraft model and aircraft speed with the flight information in the airport data system to obtain the aircraft flight number and aircraft mass. The control processing system (4) is used to obtain the mid-span coupled dynamic displacement and the mid-span coupled dynamic displacement curve of the aircraft-loaded bridge according to the aircraft speed and the aircraft mass. The control processing system (4) is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs to be repaired.

10. The aircraft load bridge monitoring system based on microwave radar according to claim 9 is characterized in that: The control processing system (4) comprises an electrically connected visual recognition module (41) and a nonlinear numerical calculation module (42), wherein the visual recognition module (41) is electrically connected to the camera (3) and the airport data system, and the nonlinear numerical calculation module (42) is electrically connected to the microwave radar (1) and the target (2); The microwave radar (1) is used to emit microwaves to the target (2) and obtain the actual mid-span dynamic displacement of the aircraft-loaded bridge in real time through the echo signal, and then output it to the nonlinear numerical calculation module (42) to form the actual mid-span dynamic displacement curve. The camera (3) is used to observe the aircraft passing through the aircraft-loaded bridge and output the video to the visual recognition module (41). The visual recognition module (41) is used to analyze the video and identify the aircraft model and aircraft speed, and obtain the aircraft flight number and aircraft mass according to the flight information in the airport data system, and output them to the nonlinear numerical calculation module (42). The nonlinear numerical calculation module (42) is used to obtain the mid-span coupled dynamic displacement of the aircraft-loaded bridge and the mid-span coupled dynamic displacement curve according to the aircraft speed and the aircraft mass. The nonlinear numerical calculation module (42) is used to compare the actual mid-span dynamic displacement with the mid-span coupled dynamic displacement and determine whether the aircraft-loaded bridge needs to be repaired.

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