Scanning microwave vibration and deformation measurement method and system

Abstract

The application provides a scanning microwave vibration and deformation measurement method and system, comprising simultaneously emitting a linear frequency modulation continuous wave through a plurality of transmitting antennas, the main lobe of a synthesized beam is directed to a certain angle direction to be measured, and a vibration and deformation displacement value of a single target or multiple targets in the periodic angle direction one is obtained through a plurality of receiving antennas receiving a return wave; the vibration and deformation displacement value of a single target or multiple targets in the periodic angle direction two is obtained through phase shift control of the plurality of transmitting antennas based on the above method; and the vibration and deformation displacement value of a single target or multiple targets in other angle directions of the period is measured and extracted according to measurement requirements. According to the above scanning method, vibration and deformation displacement time sequence values of all scanning measurement points or targets are obtained. The application can solve the limitations of existing microwave vibration measurement technology, such as the need to paste a target and poor angle resolution, and solve the problems existing in the prior art in the aspects of coupling clutter interference suppression between measurement points and high signal-to-noise ratio measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vibration and deformation measurement, and in particular to a scanning microwave vibration and deformation measurement method and system. BACKGROUND

[0002] Vibration phenomena are ubiquitous in nature and engineering, and the measurement of vibration and deformation provides key sensing data for the mechanical testing, dynamic behavior observation, deformation evolution identification, etc. of engineering equipment, structures, etc., and has very important engineering application needs and value. According to the different measurement methods, it is mainly divided into contact measurement and non-contact measurement, wherein the non-contact method has obvious advantages in engineering practice because it does not need to install sensors on the measured object. At present, the measurement is mainly performed by vision and laser, but there are great limitations in measurement performance and environmental adaptability. Microwave perception-based vibration and deformation measurement is a new type of vibration and deformation measurement technology, which can realize micro and large amplitude vibration and deformation measurement. However, since the implementation premise of microwave vibration measurement technology is the reflection or strong scattering of electromagnetic waves by the measured target, in order to obtain better signal strength and multi-point identification capability, it is often necessary to arrange targets such as corner reflectors, especially when multi-point and full-field measurement of surface targets is performed. On the other hand, in actual engineering measurement, the measured object cannot be installed or pasted with targets such as corner reflectors, resulting in low signal-to-noise ratio and poor multi-point resolution capability of the measurement, and even the measurement cannot be performed. Therefore, how to realize non-target microwave vibration and deformation multi-point and full-field measurement with high signal-to-noise ratio has an urgent need, and is also the goal pursued by people in this technical field.

[0003] The existing microwave vibration and deformation measurement technology needs to paste or install targets such as corner reflectors, in order to realize effective identification, resolution and displacement measurement of multi-point or full-field measurement points, which will bring additional mass in the measurement process, affect the dynamic characteristics of itself, and since the fixed targets need to be installed, it brings inconvenience to the installation test. In addition, the existing technology needs to rely on a large number of transceiver channel numbers to achieve high angle resolution, and there are also great difficulties in coupling and clutter interference suppression between measurement points and high signal-to-noise ratio measurement.

[0004] Therefore, it is necessary to propose a new technical solution to solve the above technical problems. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a scanning microwave vibration and deformation measurement method and system.

[0006] According to the scanning microwave vibration and deformation measurement method provided by the present application, the method comprises the following steps:

[0007] Step S1: by simultaneously transmitting linear frequency continuous wave through multiple transmitting antennas, phase shift control is performed on the transmitting signals of the multiple transmitting antennas, and the main lobe of the synthesized beam is directed to a certain angle direction to be measured;

[0008] Step S2: by receiving echoes through multiple receiving antennas, multi-channel baseband signals are obtained, nonlinear demodulation processing is performed on the collected multi-channel baseband signals, and vibration and deformation displacement values of a single target or measuring point in the periodic angle direction one are obtained, or vibration and deformation displacement values of multiple targets or measuring points in the periodic angle direction one are obtained;

[0009] Step S3: by phase shift control of the multiple transmitting antennas, angle deviation of the main lobe of the synthesized beam is completed, and vibration and deformation displacement values of a single target or measuring point in the periodic angle direction two are extracted based on the above method, or vibration and deformation displacement values of multiple targets or measuring points in the periodic angle direction two are extracted; according to measurement requirements, vibration and deformation displacement values of a single target or measuring point in other periodic angle directions are measured and extracted, or vibration and deformation displacement values of multiple targets or measuring points in other periodic angle directions are measured and extracted.

[0010] Step S4: according to the above scanning method, cyclic angle direction scanning vibration and deformation measurement is carried out at a certain periodic time interval, and vibration and deformation displacement time sequence values of all scanning measuring points or targets are obtained.

[0011] Preferably, the phase shift control method of the transmitting signals of the multiple transmitting antennas in step S1 is as follows:

[0012] Suppose the angle of the target or measuring point to be measured in the microwave front-end radiation wave is θ0, then the phase shift of each antenna of the transmitting antenna array is controlled as follows: taking the first antenna as a reference point, the phase shifts are 0, 2πd2sinθ0 / λ c , …, 2πd K sinθ0 / λ c , respectively, where d k (k=2,…N) is the distance between the kth transmitting antenna and the first transmitting antenna, and λ c is the wavelength corresponding to the center frequency of the linear frequency continuous wave;

[0013] The arrangement mode of the transmitting antenna array is equidistant arrangement or non-equidistant sparse arrangement, and the arrangement mode of the transmitting antenna array needs to be arranged horizontally for horizontal angle scanning, needs to be arranged vertically for pitch angle scanning, and needs to be arranged in both horizontal and vertical directions for space angle scanning.

[0014] Preferably, the scanning angle and its distribution are determined according to measurement requirements or the spatial arrangement of the measuring points or targets.

[0015] Preferably, the scanning angle direction required for steps S1-S3 is obtained based on prior knowledge, the requirements of the test, or the preliminary positioning information of the full-field measurement points.

[0016] Preferably, the nonlinear demodulation method for extracting the vibration and deformation displacement values ​​of a single target or measuring point, or multiple targets or measuring points, in a certain scanning cycle angular direction in steps S2-S4 is as follows:

[0017] The element values ​​x(p, θ) of the vibration and deformation displacement sequence of the target or measuring point in the current scanning cycle are extracted using a nonlinear demodulation method. s R) is calculated as follows:

[0018]

[0019] In the formula, x(p, θ) s R, iT sweep ) represents the p-th cyclic scan, with the beam scanning angle being θ. s The displacement sequence element value of the target or measuring point under test, with a transmission sweep period of i and a current scanning angle distance of R, is T. sweep The frequency sweep period for transmitting a linear frequency modulated continuous wave via the transmitting antenna is defined as follows: arg[·] represents the operation of taking complex phase values, N is the number of single-channel baseband signal elements in each frequency sweep period, n is the index of the single-channel baseband signal element in each frequency sweep period, and T is the number of elements in the frequency sweep period. s The sampling frequency and time of the baseband signal; s B (p, θ) s iT, nT s ) represents the p-th cyclic scan, with a beam scanning angle of θ. s The matrix consists of M baseband signals from the i-th transmit frequency sweep cycle. The column vectors of the matrix represent the baseband signals of the m-th channels (m = 1, 2, ..., M), where j is the imaginary unit. d is the estimated beat frequency corresponding to the distance between the measured target or measuring point. rxm (m=1,…,M) represent the distances from the m-th receiving antenna to the first receiving antenna, where d rx1 =0,λ c The wavelength corresponding to the center frequency of a linear frequency modulated continuous wave;

[0020] The number of frequency sweep cycles i for each scanning angle transmission is a positive integer equal to or greater than 1. When it is greater than 1, x(p, θ) is required as needed. s R) takes x(p, θ) within multiple transmit frequency sweep cycles during the current scan period. s R, iT sweep The average or optimal value of the sequence, or other selected values.

[0021] Preferably, the cyclic scanning method in step S4 is as follows:

[0022] According to the measurement requirement, the scanning angle θ is sequentially transformed by phase shift control s Wherein s = 0, 2, …, S-1, and the vibration and deformation displacement element values of all targets or measuring points in the scanning range are extracted according to the above method.

[0023] The present application also provides a scanning microwave vibration and deformation measurement system, which applies the scanning microwave vibration and deformation measurement method described above, and comprises the following modules:

[0024] A microwave transceiver is used to simultaneously emit multi-channel linear frequency continuous wave microwave signals through the array of transmitting antennas, receive echo signals, output multi-channel baseband signals, and realize cyclic scanning of the synthesized beam by phase shift control of the transmitting antennas.

[0025] A control and processor is used to control the beam scanning of the microwave transceiver, the acquisition of baseband signals, and the extraction of vibration and deformation displacement of the measured targets or measuring points.

[0026] A display and storage module is used to display or save the vibration and deformation displacement sequence values or waveforms of the system scanning angle distribution and all measured targets or measuring points, and other intermediate processing information.

[0027] Preferably, the microwave transceiver comprises a linear frequency continuous wave microwave signal source, a power divider, a mixer, a phase shifter, an amplifier, an array of transmitting antennas, and an array of receiving antennas. The signal source is connected to the power divider, one part of which is connected to the phase shifter and used to radiate signals through the transmitting antennas, and the other part is used as a local oscillator signal for mixing. The phase shifter is connected to the transmitting antennas and used to control the main lobe of the synthesized beam emitted by the array of transmitting antennas to point to a certain set scanning angle by phase shift control. The array of receiving antennas is connected to the amplifier, and the output amplified signal is connected to the mixer, which is mixed with the local oscillator signal at the end of the mixer to output multi-channel baseband signals.

[0028] Preferably, the array of transmitting antennas can be arranged horizontally, vertically, or in a combination of both according to the scanning requirements of the spatial azimuth angle and the elevation angle. The number of transmitting antennas in the array of transmitting antennas is greater than or equal to 2, and the spacing between the transmitting antennas is arranged in equal or unequal intervals. The number of receiving antennas in the array of receiving antennas is greater than or equal to 1, and the distance between the receiving antennas is arranged in equal or unequal intervals.

[0029] The number of phase shifters is equal to the number of transmitting antennas, and the phase shifters can also use time delay lines or other devices with phase shift control function.

[0030] Preferably, the control and processor comprises a scanning control unit and a signal acquisition and processing unit.

[0031] The scanning control unit is used for phase shift control of the transmitting antenna channel, control of the cyclic scanning period and control of other conventional parameters of the microwave transceiver; the phase shift control is realized by configuration of the phase shifter connected to each transmitting antenna.

[0032] The signal acquisition and processing unit is used for synchronous acquisition of the multi-channel baseband signal and extraction of the vibration and deformation displacement values of the measured target or measuring point through processing of the acquired baseband signal.

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

[0034] 1. The present application can realize vibration and deformation measurement of the specified beam angle direction measuring point or target by establishing the beam synthesis scanning and the microwave vibration and deformation measurement method and system under the mechanism, solves the limitation of needing to paste or install corner reflector target for microwave multi-measuring point and full-field measuring point vibration and deformation measurement of the object including but not limited to the surface structure object, reduces the influence on the dynamic performance of the measured structure, improves the convenience and operation simplicity of the test, and can be applied to occasions where the target cannot be pasted;

[0035] 2. The present application can conveniently greatly improve the resolution in the angle dimension through the beam synthesis scanning type microwave vibration and deformation measurement of the phase shift control, solves the limitation of needing to rely on a large number of transceiving channel numbers to realize higher angle resolution through virtual array reconstruction for the existing microwave full-field vibration measurement technology, and realizes high spatial resolution vibration and deformation measurement of the multi-measuring point or full-field measuring point;

[0036] 3. The present application can effectively solve the problem of clutter interference caused by other targets or measuring points through the beam synthesis focusing based vibration and deformation measurement of a certain specific angle direction measuring point or target each time, effectively solves the problem of coupling clutter interference of the adjacent angle image target or measuring point, greatly improves the measurement precision and reliability. At the same time, due to the vibration and deformation measurement mechanism and method of the beam synthesis focusing, the signal-to-noise ratio of the measured target or measuring point vibration and deformation measurement is greatly improved, the noise interference is effectively reduced, and the vibration and deformation measurement difficulty of the prior art in the aspects of ultra-high precision, ultra-micro amplitude and long distance is solved. BRIEF DESCRIPTION OF DRAWINGS

[0037] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings:

[0038] Figure 1 The flow chart of the scanning type microwave vibration and deformation measurement method of the present application;

[0039] Figure 2The schematic diagram of the horizontal arrangement of the transmitting antenna array and the phase shift control relationship thereof in the embodiment of the present application;

[0040] Figure 3 The schematic diagram of the horizontal orientation angle, the pitch angle and the spatial angle of the scanning angle in the embodiment of the present application;

[0041] Figure 4 The structural block diagram of the scanning microwave vibration and deformation measurement system of the present application;

[0042] Figure 5 The overall structural block diagram of the microwave transceiver in the embodiment of the present application. DETAILED DESCRIPTION

[0043] The present application will be described in detail below with specific embodiments. The following embodiments will help the person skilled in the art to further understand the present application, but do not limit the present application in any form. It should be pointed out that, for those skilled in the art, without departing from the concept of the present application, a number of changes and improvements can be made. These all belong to the protection scope of the present application.

[0044] Example 1:

[0045] The present application provides a scanning microwave vibration and deformation measurement method, which comprises the following steps:

[0046] Step S1: simultaneously emitting linear frequency continuous waves through a plurality of transmitting antennas, performing phase shift control on the transmitting signals of the plurality of transmitting antennas, and making the main lobe of the synthesized beam face a certain angle direction to be measured.

[0047] The method for performing phase shift control on the transmitting signals of the plurality of transmitting antennas is as follows:

[0048] Supposing that the target or the measuring point to be measured is at the angle θ0 of the microwave front-end radiation wave, the phase shifts of the transmitting antennas of the transmitting antenna array are controlled as follows: taking the first antenna as the reference point, the phase shifts are 0, 2πd2sinθ0 / λ c , …, 2πd K sinθ0 / λ c , respectively, wherein d k (k = 2, …N) is the distance between the kth transmitting antenna and the first transmitting antenna, and λ c is the wavelength corresponding to the center frequency of the linear frequency continuous wave;

[0049] The arrangement mode of the transmitting antenna array is equidistant arrangement or unequal interval sparse arrangement, the arrangement mode of the transmitting antenna array needs to arrange the transmitting antenna array horizontally for horizontal angle scanning, needs to arrange the transmitting antenna array vertically for pitch angle scanning, and needs to arrange the transmitting antenna array in both horizontal and vertical directions for spatial angle scanning.

[0050] Step S2: receiving the echo through multiple receiving antennas to obtain a multi-channel baseband signal, and performing nonlinear demodulation processing on the collected multi-channel baseband signal to obtain the vibration and deformation displacement value of a single target or measuring point in the periodic angle direction one, or to obtain the vibration and deformation displacement value of multiple targets or measuring points in the periodic angle direction one.

[0051] Step S3: completing the angle shift of the main lobe of the synthesized beam through the phase shift control of the multiple transmitting antennas, extracting the vibration and deformation displacement value of a single target or measuring point in the periodic angle direction two based on the above method, or extracting the vibration and deformation displacement value of multiple targets or measuring points in the periodic angle direction two; according to the measurement requirement, measuring and extracting the vibration and deformation displacement value of a single target or measuring point in other periodic angle directions, or measuring and extracting the vibration and deformation displacement value of multiple targets or measuring points in other periodic angle directions.

[0052] Step S4: according to the above scanning method, carrying out the scanning vibration and deformation measurement in the cycle angle direction at a certain periodic time interval to obtain the vibration and deformation displacement time sequence value of all scanning measuring points or targets.

[0053] The scanning angle and its distribution are determined according to the measurement requirement or the spatial arrangement of the measuring points or targets.

[0054] The scanning angle direction required in steps S1-S3 is obtained according to the prior knowledge or the measured requirement or the preliminary positioning information of the field measuring points.

[0055] The nonlinear demodulation method for extracting the vibration and deformation displacement value of a single target or measuring point, multiple targets or measuring points in a scanning periodic angle direction in steps S2-S4 is as follows:

[0056] The element value x(p, θ s , R) of the vibration and deformation displacement sequence of the measured target or measuring point in the current scanning periodic is calculated as:

[0057]

[0058] In the formula, x(p, θ s , R, iT sweep ) represents the displacement sequence element value of the measured target or measuring point in the pth cycle scanning, the angle of the beam scanning is θ s , the transmitting frequency sweeping periodic is i, and the current scanning angle distance is R, T sweep is the frequency sweeping periodic of the transmitting antenna transmitting the linear frequency modulation continuous wave, arg[·] is the operation of taking the complex phase value, N is the number of single-channel baseband signal elements in each frequency sweeping periodic, n is the sequence number of single-channel baseband signal elements in each frequency sweeping periodic, and T sis the baseband signal sampling frequency time; s B (p, θ s , iT, nT s ) is the pth cycle scanning, the beam scanning angle is θ s , the ith transmitting frequency scanning period is composed of a matrix of M channel baseband signals, the column vector of the matrix is the baseband signal of the mth channel (m = 1, 2, …, M), j is the imaginary unit, is the beat frequency estimation value corresponding to the distance of the measured target or measuring point, d rxm (m = 1, …, M) is the distance from the mth receiving antenna to the first receiving antenna, where d rx1 = 0, λ c is the wavelength corresponding to the center frequency of the linear frequency modulation continuous wave.

[0059] The above nonlinear demodulation calculation method can also be transformed into other demodulation calculation formulas without changing the essence.

[0060] The number of scanning angle transmitting frequency scanning periods i is equal to 1 or a positive integer greater than 1. When it is greater than 1, x(p, θ s , R) takes the average value or the optimal value or other selected value of the x(p, θ s , R, iT sweep ) sequence in the time of multiple transmitting frequency scanning periods of the scanning period.

[0061] The cyclic scanning method in step S4 is:

[0062] According to the measurement requirements, the scanning angle θ s is sequentially transformed by phase shift control, where s = 0, 2, …, S-1 is a positive integer, and the vibration and deformation displacement element values of all targets or measuring points in the scanning range are extracted according to the above method.

[0063] For a certain target or measuring point, it is assumed that it is located at a scanning angle θ s , and the distance from the antenna is R. The final vibration and deformation displacement time sequence is [x(1, θ s , R), …, x(p, θ s , R), …], p = 1, 2, …, P is the cycle scanning period number, and the time interval is the time used for one cycle scanning or the cycle scanning period.

[0064] The vibration and deformation displacement time sequence [x(1, θ s , R), …, x(p, θ s , R), …] of the above certain target or measuring point is processed according to the overall constant phase as needed. The processing method is to subtract the average value of the sequence or subtract the initial value of the sequence or other similar methods.

[0065] Example 2:

[0066] The application also provides a scanning microwave vibration and deformation measurement system, characterized in that the system applies the scanning microwave vibration and deformation measurement method described above, and the system comprises the following modules:

[0067] The microwave transceiver is used for simultaneously transmitting multi-channel linear frequency continuous wave microwave signals through the array of transmitting antennas, receiving echo signals, outputting multi-channel baseband signals, and realizing cyclic scanning of the synthesized beam through phase shift control of the transmitting antennas.

[0068] The microwave transceiver comprises a linear frequency continuous wave microwave signal source, a power divider, a mixer, a phase shifter, an amplifier, an array of transmitting antennas, and an array of receiving antennas; the signal source is connected with the power divider, a part of which is connected with the phase shifter, and the other part is used as a local oscillator signal for mixing; the phase shifter is connected with the transmitting antennas, and is used for adjusting the main lobe of the synthesized beam emitted by the array of transmitting antennas to a certain set scanning angle through phase shift control; the array of receiving antennas is connected with the amplifier, and the output amplified signal is connected with the mixer, and the multi-channel baseband signals are outputted after mixing with the local oscillator signal at the end of the mixer.

[0069] The array of transmitting antennas can be arranged horizontally, vertically or in a combination of the two according to the scanning requirements of the spatial azimuth angle and the elevation angle; the number of the transmitting antennas of the array of transmitting antennas is greater than or equal to 2, and the intervals between the transmitting antennas are arranged in equal or unequal intervals; the number of the receiving antennas of the array of receiving antennas is greater than or equal to 1, and the intervals between the receiving antennas are arranged in equal or unequal intervals; the number of the phase shifters is equal to the number of the transmitting antennas, and the phase shifters can also use time delay lines or other devices with phase shift control function.

[0070] The control and processor is used for controlling the beam scanning of the microwave transceiver, the baseband signal acquisition, and the vibration and deformation displacement extraction of the measured target or measuring point.

[0071] The control and processor comprises a scanning control unit and a signal acquisition and processing unit; the scanning control unit is used for controlling the phase shift of the transmitting antenna channel, the control of the cyclic scanning period, and the control of other conventional parameters of the microwave transceiver; the phase shift control is realized through the configuration of the phase shifter connected with each transmitting antenna. The signal acquisition and processing unit is used for synchronously acquiring the multi-channel baseband signals, and extracting the vibration and deformation displacement values of the measured target or measuring point through processing of the acquired baseband signals.

[0072] The display and storage module is used for displaying or storing the scanning angle distribution of the system, the vibration and deformation displacement sequence values or waveforms of all the measured targets or measuring points, and other intermediate processing information.

[0073] Example 3:

[0074] Example 3 is a preferred embodiment of Examples 1 and 2, and is used to illustrate the present invention in more detail.

[0075] This invention provides a scanning microwave vibration and deformation measurement method, such as... Figure 1 As shown, multiple transmitting antennas simultaneously transmit linear frequency modulated continuous waves. Phase shift control is applied to the transmitted signals from these antennas to align the main lobe of the synthesized beam towards a specific angular direction being measured. Simultaneously, multiple receiving antennas receive the echoes, obtaining multi-channel baseband signals. Nonlinear demodulation processing is then performed on the acquired multi-channel baseband signals to obtain the vibration and deformation displacement values ​​of a single target (or measurement point) or multiple targets (or measurement points) within that angular direction.

[0076] Then, by controlling the phase shift of multiple transmitting antennas, the angle shift of the main lobe of the synthetic beam is achieved. Based on the above method, the vibration and deformation displacement values ​​of a single target (or measuring point) or multiple targets (or measuring points) in the second angle direction of the period are extracted.

[0077] According to the measurement requirements, measure and extract the vibration and deformation displacement values ​​of a single target (or measuring point) or multiple targets (or measuring points) in other angular directions during the cycle.

[0078] Based on the above scanning method, cyclic scanning vibration and deformation measurements are carried out at certain intervals to obtain the vibration and deformation displacement time series values ​​of all scanning measurement points or targets.

[0079] Beamforming and main lobe orientation angle control method for simultaneous transmission of linear frequency modulated continuous waves by multiple transmitting antennas: Assume that the angle of the target or measuring point to be measured at the microwave front end is θ0, based on prior knowledge, the requirements of the test, or the preliminary positioning information of the microwave full-field measuring point.

[0080] like Figure 2 As shown, with the first antenna as the reference point, the phase shifts are 0 and 2πd² sinθ₀ / λ. c , …, 2πd K sinθ0 / λ c In the formula, d k (k = 2, ..., N) represents the distance between the k-th transmitting antenna and the first transmitting antenna, λ cThis refers to the wavelength corresponding to the center frequency of the linear frequency modulated continuous wave. Phase shift control includes, but is not limited to, the use of phase shifters, time delay lines, or other phase shift control techniques. The transmitting antenna array can be arranged with equal spacing or with unequal spacing and sparse arrangement. The scanning angle and its distribution are determined according to measurement needs, or the spatial arrangement of the measurement points or targets. To achieve control of transmitted beamforming and focusing, for horizontal angle scanning, the transmitting antenna array needs to be arranged horizontally; for elevation angle scanning, the transmitting antenna array needs to be arranged vertically; and for spatial angle scanning, the transmitting antenna array needs to be arranged both horizontally and vertically. Figure 3 As shown, for example, to measure the vibration and deformation of two targets or measuring points with spatial distances R1 and R2, the beamforming angle of the horizontally arranged transmitting antenna needs to be θ. h The beamformation of the vertically arranged transmitting antennas is combined to form an elevation angle of θ. v To achieve the aforementioned beamforming control, the specific arrangement of the transmitting antenna array can be linear, planar, circular, or other regular or irregular arrangements as needed.

[0081] Method for extracting vibration and deformation displacement values ​​of a single target (measuring point) or multiple targets (measuring points) at a certain angle during a certain scanning cycle: Let the transmitted signal of the first transmitting antenna be s1(t). According to the phase shift control method of the transmitting antenna array, the synthesized transmitted signal is:

[0082] s T (t, θ) = a(θ) H s1(t)a(θ0),

[0083] In the formula, (·) H For the conjugate transpose of a matrix, (·) T This is the transpose operation of a matrix, where j is the imaginary unit, and 2πd k sinθ0 / λ c Let d be the phase shift value of the k-th transmitting antenna relative to the first transmitting antenna (reference point). k Let λ be the distance between the k-th transmitting antenna and the first transmitting antenna. c θ0 is the wavelength corresponding to the center frequency of the linear frequency modulated continuous wave (LFM), and θ0 is the beam scanning angle with the central axis as the reference. The signals transmitted by each transmitting antenna are LFM continuous wave signals or other signals equivalent to LFM continuous waves.

[0084] The transmitted signal s1(t) from the first transmitting antenna is represented as:

[0085]

[0086] In the formula A TLet f0 be the amplitude of the transmitted signal, f0 be the carrier start frequency, B be the transmission bandwidth, and T be the transmission bandwidth. sweep φ0 is the sweep frequency period, t is the time variable within the sweep frequency period, and φ0 is the initial phase.

[0087] To facilitate the explanation of the test principle, it is assumed that the transmitting antennas are arranged at equal intervals, with an interval of d (i.e., d k = (k-1)d), then the transmitted signal for each sweep cycle synthesized in the direction of angle θ is:

[0088]

[0089] After mixing with the local oscillator signal and low-pass filtering, the baseband signal of the i-th sweep cycle of the channel corresponding to the first receiving antenna is obtained as follows:

[0090]

[0091] In the formula, ψ=πd(sinθ0-sinθ) / λ c A B T represents the amplitude of the baseband signal. sweep The sweep period is R, the distance between the target or measurement point and the microwave transceiver is R, λ0 is the wavelength corresponding to the starting frequency of the linear frequency modulated continuous wave, and x(iT) is the wavelength of the target or measurement point and the microwave transceiver. sweep ) represents the element value of the vibration and deformation displacement value sequence of the target or measuring point in the current scanning cycle corresponding to the i-th frequency sweep cycle, and K is the number of transmitting antennas transmitting signals simultaneously. The number of transmission cycles i for each scanning angle is a positive integer equal to or greater than 1. When it is greater than 1, the average value, optimal value, or other selected value within multiple transmission cycles is taken as needed.

[0092] set up Through beat frequency f b After demodulation, the phase complex vector is expressed as follows: It can be seen that through spatial synthesis of the transmitted beam, taking an equally spaced transmission array as an example, the mathematical model derivation and demodulation analysis of the baseband signal show that the vibration / deformation displacement of the measured target or measuring point is related to... They form a certain linear relationship, and the constant phase of the linear relationship is... At the same time, the magnitude of the phase complex vector increased. The signal-to-noise ratio is significantly improved by a factor of 1.5. When θ = θ0, the amplitude is 1 / 3 that of a single transmitting antenna. The power of the single transmitting antenna is K. 2 The signal intensity radiated to the target or measuring point is significantly increased due to the beamforming and focusing vibration and deformation measurement mechanism and method. This significantly improves the signal-to-noise ratio of vibration and deformation measurement of the target or measuring point, effectively reducing noise interference. This provides an effective method for solving the challenges of ultra-high precision, ultra-low amplitude, and long-distance vibration and deformation measurement in microwave applications.

[0093] When the spacing of the transmitting array antennas is inconsistent, according to the principle of beam spatial superposition and synthesis, it is equivalent to non-uniform beam superposition and synthesis, which only affects the ratio of the main and side lobes of the synthesized beam. The same applies to the mechanism and method of scanning beam vibration and deformation measurement derived and established above.

[0094] Furthermore, the complex vector of the baseband signal phase for the antenna channel scanning angle θ0 of the receiving array can be expressed as:

[0095]

[0096] In the formula, λ c Let θ0 be the wavelength corresponding to the center frequency of the linear frequency modulated continuous wave, and θ0 be the beam scanning angle with the central axis as the reference. rxm (m=1,…,M) represent the distances from the m-th receiving antenna to the first receiving antenna, where d rx1 =0, where M is the number of receiving antennas, greater than or equal to 1. The distance between the receiving antennas can be an equal or unequal sparse array.

[0097] Therefore, the element values ​​x(p, θ) of the vibration and deformation displacement sequence of the target or measuring point in the current scanning cycle are extracted by nonlinear demodulation method. s R) is calculated as follows:

[0098]

[0099] In the formula, x(p, θ) s R, iT sweep ) represents the p-th cyclic scan, with the beam scanning angle being θ. s The displacement sequence element value of the target or measuring point under test, with a transmission sweep period of i and a current scanning angle distance of R, is T. sweep The frequency sweep period for transmitting a linear frequency modulated continuous wave via the transmitting antenna is defined as follows: arg[·] represents the operation of taking complex phase values, N is the number of single-channel baseband signal elements in each frequency sweep period, n is the index of the single-channel baseband signal element in each frequency sweep period, and T is the number of elements in the frequency sweep period. s The sampling frequency and time (s) for the baseband signal. B (p, θ) s iT, nT s ) represents the p-th cyclic scan, with a beam scanning angle of θ. s The matrix consists of M baseband signals from the i-th transmit frequency sweep cycle. The column vectors of the matrix represent the baseband signals of the m-th channels (m = 1, 2, ..., M), where j is the imaginary unit. d is the estimated beat frequency corresponding to the distance between the measured target or measuring point. rxm(m=1,…,M) represent the distances from the m-th receiving antenna to the first receiving antenna, where d rx1 =0,λ c This represents the wavelength corresponding to the center frequency of a linearly frequency-modulated continuous wave. The aforementioned nonlinear demodulation calculation method can also be transformed into other demodulation calculation formulas without changing its fundamental nature.

[0100] The number of frequency sweep cycles i for each scan angle transmission is a positive integer equal to or greater than 1. When it is greater than 1, x(p, θ) is used as needed. s R) takes x(p, θ) within multiple transmit frequency sweep cycles during the current scan period. s R, iT sweep The average or optimal value of the sequence, or other selected values.

[0101] As can be seen from the above analysis and derivation, this invention, by establishing a beamforming scanning method and system for measuring microwave vibration and deformation under this mechanism, performs vibration and deformation measurements on a specific measurement point or target at a certain angle direction each time based on beamforming focusing. This significantly suppresses clutter interference from other targets or measurement points outside that angle direction (see the signal intensity amplitude scaling factor based on different angle directions after beamforming focusing). It can be seen that the scanning angle direction is significantly higher than that of the nearby direction, which effectively solves the problem of clutter interference caused by other targets or measurement points. In particular, it effectively solves the problem of coupling clutter interference from nearby angle targets or measurement points, thereby greatly improving the accuracy and reliability of the measurement.

[0102] Cyclic scanning method: Based on the measurement requirements, the scanning angle θ is changed sequentially through phase shift control. s Where s = 0, 2, ..., S-1, are positive integers, and the vibration and deformation displacement element values ​​of all targets or measuring points within the scanning range are extracted according to the method described above. For a certain target or measuring point, let its scanning angle be θ. s The distance from the antenna is R, and the final vibration and deformation displacement time series is [x(1, θ s ,R),…,x(p,θ) s ,R),…],p=1,2,…,P is the cyclic scan cycle number, and the time interval is the time taken for one cyclic scan or the cyclic scan cycle.

[0103] The vibration and deformation displacement time series of a certain target or measuring point [x(1, θ] s ,R),…,x(p,θ) s ,R),…|,The constant phase of the whole can be processed as needed, by subtracting the average value of the sequence or the initial value of the sequence or other similar methods.

[0104] Therefore, by establishing a beamforming scanning method and system for measuring microwave vibration and deformation under this mechanism, this invention can realize the vibration and deformation measurement of a specified beam angle direction or target. It solves the limitation that microwave multi-point and full-field measurement of vibration and deformation of objects including but not limited to surface structures requires the pasting or installation of targets such as corner reflectors, reduces the impact on the dynamic performance of the tested structure, improves the convenience and ease of operation of testing, and is applicable to occasions where it is not possible to paste targets.

[0105] In addition, this invention can conveniently and significantly improve the resolution of the angular dimension by using phase-shift controlled beamforming scanning microwave vibration and deformation measurement. The scanning angle resolution of 1° and below can be easily achieved by phase-shift control. However, if the existing multi-transmitter multi-receiver array antenna is used to achieve an angle resolution of 1°, more than 100 physical or virtual channels are required. This invention solves the limitation of existing microwave full-field vibration measurement technology, which requires a large number of transmit and receive channels for virtual array reconstruction to achieve high angle resolution. It enables vibration and deformation measurement with high spatial resolution at multiple measurement points or full-field measurement points.

[0106] The present invention also provides a scanning microwave vibration and deformation measurement system, such as Figure 4 As shown, it includes:

[0107] Microwave transceiver: Used to simultaneously transmit multiple channels of linear frequency modulated continuous wave microwave signals through a transmitting antenna array, receive echo signals, output multiple channels of baseband signals, and achieve cyclic scanning of the synthesized beam through phase shift control of the transmitting antenna.

[0108] like Figure 5 As shown, the microwave transceiver includes a linear frequency modulated continuous wave microwave signal source, a power divider, a mixer, a phase shifter, an amplifier, a transmitting antenna array, and a receiving antenna array. The signal source is connected to the power divider, with one part connected to the phase shifter, radiating the signal through the transmitting antenna, and the other part serving as the local oscillator signal for mixing. The phase shifter is connected to the transmitting antenna and is used to adjust the main lobe of the synthesized beam transmitted by the transmitting antenna array towards a set scanning angle. The receiving antenna array is connected to the amplifier, and the amplified output signal is connected to the mixer, where it is mixed with the local oscillator signal to output a multi-channel baseband signal. The transmitting antenna array can be arranged horizontally, vertically, or a combination of both, depending on the spatial azimuth and elevation scanning requirements. The transmitting antenna array must have at least two transmitting antennas, spaced evenly or unequally; the receiving antenna array must have at least one receiving antenna, spaced evenly or unequally. The number of phase shifters is equal to the number of transmitting antennas. The phase shifters can also be time delay lines or other devices with phase shift control functions.

[0109] Control and Processor: Used to control the beam scanning of the microwave transceiver, baseband signal acquisition, and vibration and deformation displacement extraction of the measured target or measurement point.

[0110] The control and processor includes a scanning control unit and a signal acquisition and processing unit. The scanning control unit is used for phase shift control of the transmitting antenna channels, control of the cyclic scanning period, and control of other conventional parameters of the microwave transceiver; the phase shift control is achieved through the configuration of phase shifters connected to each transmitting antenna. The signal acquisition and processing unit is used for synchronous acquisition of multi-channel baseband signals, and for processing the acquired baseband signals to extract vibration and deformation displacement values ​​of the target or measurement point.

[0111] Display and save module: used to display or save, but not limited to, the system scanning angle distribution and the vibration and deformation displacement sequence values ​​or waveforms of all measured targets or measurement points, as well as other intermediate processing information.

[0112] Those skilled in the art can understand this embodiment as a more specific description of Embodiment 1 and Embodiment 2.

[0113] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0114] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A scanning microwave vibration and deformation measurement method, characterized in that, The method includes the following steps: Step S1: Simultaneously transmit linear frequency modulated continuous waves through multiple transmitting antennas, perform phase shift control on the transmitted signals of multiple transmitting antennas, and direct the main lobe of the synthesized beam toward a certain angle direction to be measured; Step S2: Receive echoes through multiple receiving antennas to obtain multi-channel baseband signals. Perform nonlinear demodulation processing on the acquired multi-channel baseband signals to obtain the vibration and deformation displacement values ​​of a single target or measuring point in the first angular direction of the period, or obtain the vibration and deformation displacement values ​​of multiple targets or measuring points in the first angular direction of the period. Step S3: By controlling the phase shift of multiple transmitting antennas, the angle shift of the main lobe of the synthesized beam is completed. Based on the above method, the vibration and deformation displacement values ​​of a single target or measuring point in the second angle direction of the period are extracted, or the vibration and deformation displacement values ​​of multiple targets or measuring points in the second angle direction of the period are extracted. According to the measurement requirements, the vibration and deformation displacement values ​​of a single target or measuring point in other angle directions of the period are measured and extracted, or the vibration and deformation displacement values ​​of multiple targets or measuring points in other angle directions of the period are measured and extracted. Step S4: Based on the above scanning method, at certain periodic intervals, perform cyclic scanning vibration and deformation measurements in the angular direction to obtain the vibration and deformation displacement time series values ​​of all scanning measurement points or targets.

2. The scanning microwave vibration and deformation measurement method according to claim 1, characterized in that, The method for phase-shift control of the transmitted signals from multiple transmitting antennas in step S1 is as follows: Let θ0 be the angle of the radiated wave at the microwave front end of the target or measuring point to be measured. Then, the phase shifts of each antenna in the transmitting antenna array are: taking the first antenna as the reference point, the phase shifts are 0 and 2πd² sinθ0 / λ. c , …, 2πd K sinθ0 / λ c In the formula, d k ,k=2,...,N is the distance from the k-th transmitting antenna to the first transmitting antenna, λ c The wavelength corresponding to the center frequency of a linear frequency modulated continuous wave; The antenna array is arranged in a way that allows for equal spacing or sparse arrangement with unequal spacing. For horizontal angle scanning, the antenna array needs to be arranged horizontally; for pitch angle scanning, the antenna array needs to be arranged vertically; and for spatial angle scanning, the antenna array needs to be arranged both horizontally and vertically.

3. The scanning microwave vibration and deformation measurement method according to claim 1, characterized in that, The scanning angle and its distribution are determined according to the measurement needs, or the spatial arrangement of the measuring points or targets.

4. The scanning microwave vibration and deformation measurement method according to claim 1, characterized in that, The scanning angles and directions required for steps S1-S3 are obtained based on prior knowledge, the requirements of the test, or the preliminary positioning information of all measurement points.

5. The scanning microwave vibration and deformation measurement method according to claim 1, characterized in that, The nonlinear demodulation method for extracting the vibration and deformation displacement values ​​of a single target or measuring point, or multiple targets or measuring points, in a certain scanning cycle angle direction in steps S2-S4 is as follows: The element values ​​x(p,θ) of the vibration and deformation displacement sequence of the target or measuring point in the current scanning cycle are extracted using a nonlinear demodulation method. s R) is calculated as follows: In the formula, x(p,θ) s ,R,iT sweep ) represents the p-th cyclic scan, with the beam scanning angle being θ. s The displacement sequence element value of the target or measuring point under test, with a transmission sweep period of i and a current scanning angle distance of R, is T. sweep The frequency sweep period for transmitting a linear frequency modulated continuous wave via the transmitting antenna is defined as follows: arg[·] represents the operation of taking complex phase values, N is the number of single-channel baseband signal elements in each frequency sweep period, n is the index of the single-channel baseband signal element in each frequency sweep period, and T is the number of the signal elements. s The sampling frequency and time of the baseband signal; s B (p,θ s iT,nT s ) represents the p-th cyclic scan, with a beam scanning angle of θ. s The matrix consists of M baseband signals from the i-th transmit frequency sweep cycle. The column vectors of the matrix represent the baseband signals of the m-th (m=1,2,…,M) channels, where j is the imaginary unit. d is the estimated beat frequency corresponding to the distance between the measured target or measuring point. rxm ,m=1,...,M are the distances from the m-th receiving antenna to the first receiving antenna, where d rx1 =0,λ c The wavelength corresponding to the center frequency of a linear frequency modulated continuous wave; The number of frequency sweep cycles i for each scanning angle transmission is a positive integer equal to or greater than 1. When it is greater than 1, x(p,θ) is used as needed. s ,R) takes the x(p,θ) interval within multiple transmit frequency sweep cycles of the current scan period. s ,R,iT sweep The average or optimal value of the sequence, or other selected values.

6. The scanning microwave vibration and deformation measurement method according to claim 1, characterized in that, The cyclic scanning method in step S4 is as follows: Based on the measurement requirements, the scanning angle θ is changed sequentially through phase shift control. s , where s = 0, 2, ..., S-1 are positive integers, and the vibration and deformation displacement element values ​​of all targets or measuring points within the scanning range are extracted according to the above method.

7. A scanning microwave vibration and deformation measurement system, characterized in that, The system employs the scanning microwave vibration and deformation measurement method as described in any one of claims 1-6, and the system includes the following modules: Microwave transceiver: Used to simultaneously transmit multiple channels of linear frequency modulated continuous wave microwave signals through a transmitting antenna array, receive echo signals, output multi-channel baseband signals, and achieve cyclic scanning of the synthesized beam through phase shift control of the transmitting antenna; Control and Processor: Used to control the beam scanning of the microwave transceiver, baseband signal acquisition, and vibration and deformation displacement extraction of the measured target or measurement point; Display and save module: used to display or save, but not limited to, the system scanning angle distribution and the vibration and deformation displacement sequence values ​​or waveforms of all measured targets or measurement points, as well as other intermediate processing information.

8. The scanning microwave vibration and deformation measurement system according to claim 7, characterized in that, The microwave transceiver includes a linear frequency modulated continuous wave microwave signal source, a power divider, a mixer, a phase shifter, an amplifier, a transmitting antenna array, and a receiving antenna array. The signal source is connected to the power divider, part of which is connected to the phase shifter and radiates the signal through the transmitting antenna; the other part is used as the local oscillator signal for mixing. The phase shifter is connected to the transmitting antenna and is used to adjust the main lobe of the synthetic beam transmitted by the transmitting antenna array to a set scanning angle through phase shift control; the receiving antenna array is connected to the amplifier, and the output amplified signal is connected to the mixer, where it is mixed with the local oscillator signal to output a multi-channel baseband signal.

9. The scanning microwave vibration and deformation measurement system according to claim 8, characterized in that, The transmitting antenna array can be arranged horizontally, vertically, or a combination of both, depending on the spatial azimuth and elevation angle scanning requirements; the number of transmitting antennas in the transmitting antenna array must be greater than or equal to 2, and the spacing between the transmitting antennas can be equal or unequal. The number of receiving antennas in the receiving antenna array must be greater than or equal to 1, and the distance between the receiving antennas can be equal or unequal. The number of phase shifters is equal to the number of transmitting antennas, and the phase shifters can also use time delay lines or other devices with phase shift control functions.

10. The scanning microwave vibration and deformation measurement system according to claim 7, characterized in that, The control and processor includes a scanning control unit and a signal acquisition and processing unit; The scanning control unit is used for phase shift control of the transmitting antenna channel, control of the cyclic scanning period, and control of other conventional parameters of the microwave transceiver; the phase shift control is achieved through the configuration of the phase shifters connected to each transmitting antenna. The signal acquisition and processing unit is used to synchronously acquire multi-channel baseband signals and extract the vibration and deformation displacement values ​​of the target or measuring point through processing of the acquired baseband signals.

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