CN-121977690-A - Frequency domain compensation method, system and equipment for vibration signals

CN121977690ACN 121977690 ACN121977690 ACN 121977690ACN-121977690-A

Abstract

The invention relates to the technical field of signal processing, in particular to a frequency domain compensation method, a frequency domain compensation system and frequency domain compensation equipment for vibration signals, which comprise the following steps of S1, acquiring a frequency response function of a complete measurement system from a sensor to a data acquisition end, S2, acquiring a time domain vibration signal to be analyzed through the measurement system, performing fast Fourier transform on the time domain vibration signal to obtain a frequency domain representation, S3, performing compensation operation on the frequency domain representation in the frequency domain based on the frequency response function to obtain a compensated compensation frequency spectrum, wherein the compensation operation expression is Y (f) =X (f)/H (f), and S4, performing inverse fast Fourier transform on the compensation frequency spectrum to obtain the compensated high-fidelity time domain vibration signal. The invention can compensate amplitude attenuation and phase distortion of the vibration signal caused by measuring the frequency response of the system in the frequency domain at the same time and with high precision, obviously improves the signal fidelity, and has the advantages of high calculation efficiency and easy realization.

Inventors

YUAN YANBO
WANG YUHAN
SHI WEI
WU YUEHONG
WU SHA
Tao Xinjuan
LIU PENG

Assignees

浙江至控科技有限公司
浙江中控研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20260127

Claims (10)

1. A frequency domain compensation method for a vibration signal, comprising the steps of: s1, acquiring a frequency response function of a complete measurement system from a sensor to a data acquisition end; S2, acquiring a time domain vibration signal to be analyzed through a measurement system, and performing fast Fourier transform on the time domain vibration signal to obtain a frequency domain representation; S3, in a frequency domain, performing compensation operation on the frequency domain representation based on the frequency response function to obtain a compensated compensation spectrum, wherein the compensation operation expression is Y (f) =X (f)/H (f); and S4, performing inverse fast Fourier transform on the compensation frequency spectrum to obtain a compensated high-fidelity time domain vibration signal.
2. The method according to claim 1, wherein in step S1, a frequency response function of a complete measurement system from the sensor to the data acquisition end is obtained, further comprising: s11, generating a sine sweep frequency signal with constant amplitude by using a standard vibration table as known input excitation for a complete measurement system; S12, synchronously acquiring output response signals of the measurement system at each frequency point, and recording response signal amplitude A_out (f_i) and response signal phase phi_out (f_i) corresponding to the response signals; S13, calculating complex frequency response values of the measuring system at each discrete frequency point according to the standard amplitude A_in (f_i) and the standard phase phi_in (f_i) of the known input excitation at each discrete frequency point by combining the response signal amplitude and the response signal phase, wherein: Amplitude-frequency response value is |H (f_i) |=A_out (f_i)/A_in (f_i), and phase-frequency response value is +_H (f_i) =phi_out (f_i) -phi_in (f_i); and S14, performing function fitting or interpolation on the complex frequency response values on all the discrete frequency points to generate and store a continuous frequency response function covering the whole calibration frequency band.
3. The method according to claim 1, wherein in step S2, performing a fast fourier transform on the time domain vibration signal to obtain a frequency domain representation, comprises: Preprocessing the time domain vibration signal including trending processing to obtain a preprocessed signal; Windowing is carried out on the preprocessing signal to obtain a windowed signal; and performing fast Fourier transform on the windowed signal to obtain the frequency domain representation.
4. The method of frequency domain compensation of a vibration signal according to claim 1, wherein in step S3, the compensation operation includes: the compensation operation comprises amplitude compensation calculation and phase compensation calculation; The amplitude compensation calculation is to obtain a compensation spectrum amplitude |Y (f) | according to a frequency domain representation amplitude |X (f) | and a frequency response function amplitude |H (f) | according to the following formula of |Y (f) |= |X (f) |/|H (f) |; The phase compensation calculation is to obtain a compensation spectrum phase angle Y (f) according to a frequency domain representation phase angle X (f) and a frequency response function phase angle H (f), wherein the formula is as follows.
5. The method of frequency domain compensation of a vibration signal according to claim 1 or 4, further comprising suppressing noise in step S3: Introducing a preset frequency domain filter G (f) into the compensation operation, and optimizing the expression of the compensation operation to be: and Y (f) = [ X (f) = G (f) ]/H (f), wherein the gain of the frequency domain filter G (f) in the effective frequency band of the signal is 1, and the gain of the frequency domain filter G (f) is smoothly attenuated to 0 outside the effective frequency band.
6. The method of claim 5, wherein the frequency domain filter is a low pass filter or a band pass filter having a transition band: Wherein the lower limit frequency of the effective frequency band of the signal is f_low, the upper limit frequency is f_high, and the width delta f of the transition frequency band is 0.05× (f_high-f_low) < delta f <0.2× (f_high-f_low).
7. The method according to claim 6, wherein in step S4, the performing inverse fast fourier transform on the compensated spectrum to obtain a compensated high-fidelity time-domain vibration signal, further comprises: S41, taking the compensation frequency spectrum as input, executing inverse fast Fourier transform core calculation, and outputting a discrete time domain sequence; S42, carrying out windowing inverse transformation processing or directly taking a real part on the discrete time domain sequence to obtain the final compensated high-fidelity time domain vibration signal.
8. The method of frequency domain compensation of a vibration signal according to claim 1, wherein when processing a long time domain vibration signal, an overlapped segment processing framework is employed, further comprising: dividing the time domain vibration signal into a plurality of mutually overlapped frames, wherein each frame has a length L, and the overlapping length between adjacent frames is R, wherein 0< R < N; Steps S2 to S4 are sequentially executed on each frame of signal to obtain a compensated time domain signal segment corresponding to each frame; and synthesizing the compensated time domain signal segments by an overlap-add method to obtain the complete high-fidelity time domain vibration signal.
9. A frequency domain compensation system for a vibration signal, comprising: the frequency response function acquisition module acquires a frequency response function of the complete measurement system from the sensor to the data acquisition end; The vibration signal frequency domain conversion module is used for acquiring a time domain vibration signal to be analyzed through the measurement system and performing fast Fourier transform on the time domain vibration signal to obtain a frequency domain representation; The frequency domain inverse filtering compensation module is used for executing compensation operation on the frequency domain representation based on the frequency response function in a frequency domain to obtain a compensated compensation spectrum, wherein the compensation operation expression is Y (f) =X (f)/H (f); and the compensation time domain signal synthesis module is used for performing inverse fast Fourier transform on the compensation frequency spectrum to obtain a compensated high-fidelity time domain vibration signal.
10. A computer device comprising a memory and a processor, the memory having stored therein computer readable instructions which, when executed by the processor, cause the processor to perform the steps of a method of frequency domain compensation of a vibration signal according to any one of claims 1 to 8.

Description

Frequency domain compensation method, system and equipment for vibration signals Technical Field The present invention relates to the field of signal processing technologies, and in particular, to a method, a system, and an apparatus for frequency domain compensation of a vibration signal. Background In the industrial fields of rotary machinery, aerospace, vehicle engineering and the like, the state monitoring and fault diagnosis of equipment are key to guaranteeing safety, preventing accidents and realizing predictive maintenance. Vibration signal analysis is one of the most core technical means, and dynamic response signals are acquired through an acceleration sensor arranged on equipment, so that characteristic information such as frequency, amplitude, phase and the like which reflect the health state of the equipment is extracted. However, in practical engineering applications, there is a complete measurement chain between the physical vibration source and the digital signal available for analysis, including sensors, transmission cables, signal conditioners, data acquisition cards, and the like. The measuring chain itself acts as a physical system with non-ideal frequency-dependent dynamics, i.e. its frequency response function is not a flat straight line. The method mainly comprises 1) amplitude distortion, namely inconsistent sensitivity of a system to signals with different frequencies, distortion of amplitude proportion relation of frequency components in the signals, abnormal amplification or excessive attenuation of the signals in certain frequency bands (especially near the natural frequency and cut-off frequency of a sensor), and 2) phase distortion, namely nonlinear and inconsistent phase delay introduced by the system to the different frequency components, so that original phase relation among the different frequency components in the signals is destroyed, and waveform distortion is caused. These distortions make the signal observed by the analyst already not the real vibration state of the device, seriously affecting the accuracy of the subsequent processing of spectrum analysis, envelope demodulation, order analysis, etc., possibly leading to masking of early failure features or generation of false frequency components, thus causing erroneous or missed judgment. In order to overcome the above-mentioned distortion problem, various compensation methods have been proposed in the prior art. One common approach is to compensate in the time domain, for example by designing an inverse filter to convolutionally filter the acquired signal. The method is visual, but has the obvious defects that firstly, the time domain convolution operation amount is huge, especially for long sequence data, the real-time requirement of on-line monitoring is difficult to meet, secondly, the effect of the method is highly dependent on an accurate time domain impact response model of a measuring system, the acquisition and implementation difficulty of the model are high, and finally, a plurality of time domain methods are more focused on amplitude recovery, the compensation capacity for nonlinear phase distortion is limited, and phase information is vital for precise diagnosis such as transmission path analysis and acoustic imaging. Another type of scheme is based on analog hardware, and adopts a compensation network to integrate with the sensor, so as to synthesize more ideal system response. The method has poor flexibility, is difficult to adapt to different measurement chain configurations, has limited compensation precision, and is often designed to solve specific problems such as direct current bias, and the like, but does not carry out global high-precision compensation on amplitude and phase. Therefore, a signal processing method capable of compensating amplitude and phase distortion of a vibration signal simultaneously, accurately and efficiently, and having easy implementation and strong adaptability is highly demanded in the art, so as to improve reliability and accuracy of vibration analysis in state monitoring and fault diagnosis. Disclosure of Invention The invention aims to solve the defects in the prior art, and provides a frequency domain compensation method of a vibration signal, which comprises the following steps: s1, acquiring a frequency response function of a complete measurement system from a sensor to a data acquisition end; S2, acquiring a time domain vibration signal to be analyzed through a measurement system, and performing fast Fourier transform on the time domain vibration signal to obtain a frequency domain representation; S3, in a frequency domain, performing compensation operation on the frequency domain representation based on the frequency response function to obtain a compensated compensation spectrum, wherein the compensation operation expression is Y (f) =X (f)/H (f); and S4, performing inverse fast Fourier transform on the compensation frequency spectrum to obtain a compensated high