Adaptive instantaneous frequency estimation method based on iterative demodulation time-varying filtering

An instantaneous frequency, time-varying filtering technology, applied in the testing of mechanical components, the testing of machine/structural components, advanced technology, etc., can solve the problems of poor time-frequency concentration, cross-term interference, difficult to apply to complex vibration signal analysis, etc. Achieving the effect of strong anti-noise performance

Active Publication Date: 2022-08-09
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

Commonly used non-parametric time-frequency analysis techniques such as short-time Fourier transform, wavelet transform, and Wigner-Ville distribution have problems such as poor time-frequency concentration and cross-term interference
The parametric time-frequency analysis method has the characteristics of high time-frequency resolution and strong noise robustness, but it needs to determine the kernel function for signal model matching based on prior information, which is difficult to apply to the analysis of complex vibration signals. Disadvantages of the method of calculating the instantaneous frequency

Method used

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  • Adaptive instantaneous frequency estimation method based on iterative demodulation time-varying filtering
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  • Adaptive instantaneous frequency estimation method based on iterative demodulation time-varying filtering

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Embodiment

[0057] An adaptive instantaneous frequency estimation method based on iterative demodulation and time-varying filtering. Its steps include:

[0058] S1, use the instantaneous frequency calculation method based on signal derivative normalization to initially estimate the instantaneous frequency of the signal:

[0059] S1.1, input nonlinear FM signal , model it as an AM-FM signal, and initialize it, that is n =1, , is the initial value of the instantaneous frequency iteration;

[0060] S1.2, for nonlinear FM signals Derivation to enhance the high-frequency components of the signal, for the enhanced nonlinear FM signal Normalize to get pure FM signal ;

[0061] S1.3, for pure FM signal Perform arc cosine operation and derivation to obtain the first n Instantaneous frequency of the minor cycle ;

[0062] S2, judge the first n Instantaneous frequency of the minor cycle and n -1 loop to get the instantaneous frequency Is the relative error less than the thr...

Embodiment 2

[0096] like figure 1 shown, figure 1 It is the flow chart of the adaptive instantaneous speed estimation method of the present invention, such as figure 1 shown, is characterized in that, comprises the following steps:

[0097] Step S1, utilize a kind of instantaneous frequency calculation method based on signal derivative normalization to preliminarily estimate the instantaneous frequency of the signal;

[0098] In step S3, an iterative time-varying filtering method based on demodulation technology is used to reduce the influence of noise on the estimation of the instantaneous frequency, so as to realize the accurate estimation of the instantaneous frequency.

[0099] The instantaneous frequency calculation method of step S1 specifically includes:

[0100] Nonlinear FM signals are described by an AM-FM model:

[0101]

[0102] in, represents time, , and Represent the instantaneous amplitude, instantaneous frequency and initial phase of the signal, respectively, a...

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Abstract

The invention discloses a self-adaptive instantaneous frequency estimation method based on iterative demodulation time-varying filtering. The method comprises the following steps: S1, preliminarily estimating the instantaneous frequency of a signal by using an instantaneous frequency calculation method based on signal derivative normalization; s2, reducing the influence of noise on instantaneous frequency estimation by using an iterative time-varying filtering method based on a demodulation technology, and realizing accurate estimation of the instantaneous frequency; and S3, checking whether a result accords with a set threshold value or not, and if not, continuing to execute the step S1. According to the method, the instantaneous frequency is preliminarily calculated according to the time domain characteristics of the signal derivative, prior information is not needed, the method is completely data-driven, the influence of noise on instantaneous frequency estimation is reduced by adopting iterative time-varying filtering, and the method has relatively strong anti-noise performance.

Description

technical field [0001] The invention belongs to the technical field of vibration signal processing, and in particular relates to an adaptive instantaneous frequency estimation method based on iterative demodulation and time-varying filtering. Background technique [0002] Vibration signal analysis is an important part of condition monitoring and fault diagnosis of rotating machinery. Under transient conditions, especially in the acceleration and deceleration stage of rotating machinery, it is easier to find weak features of early faults from vibration signals. However, the vibration signals of rotating machinery under transient conditions show non-stationary characteristics related to the speed of the equipment, and are seriously polluted by environmental noise. Instantaneous frequency is often used to characterize the non-stationary characteristics of vibration signals. Therefore, accurate estimation of the instantaneous frequency of vibration signals is crucial for fault...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/18G01M13/045
CPCG06F17/18G01M13/045Y02D30/70
Inventor 陈是扦王开云王红兵翟婉明
Owner SOUTHWEST JIAOTONG UNIV
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