Instantaneous frequency estimation method based on log operator and t test

Abstract

The invention discloses an instantaneous frequency estimation method based on a LoG operator and a t test. The method includes: converting original signals to a time-frequency spectrum by employing short-time Fourier transform, obtaining a plurality of ridge belts by employing a LoG detection algorithm, eliminating an abnormal value of each ridge belt by employing the t test, constructing a synthetic ridge belt with complete and clear edges through superposition, eliminating an abnormal value of the synthetic ridge belt by employing the t test, calculating a mean value curve of the synthetic ridge belt, performing smooth processing on the mean value curve, calculating a confidence interval of the smooth mean value curve at the 95% confidence level, mapping the smooth mean value curve and the confidence interval thereof to a target ridge line, obtaining a reference line and a local search interval of the target ridge line, and extracting the target ridge line by employing a non-delayed cost function. The method is applicable to estimation of the instantaneous frequency of complex multi-component variable-frequency signals, the defect of estimation of the instantaneous frequency of mechanical vibration signals of the conventional method is overcome, the accuracy of estimation results is high, and engineering application is facilitated.

Description

technical field [0001] The invention relates to the field of state monitoring and fault diagnosis of rotating machinery, in particular to an instantaneous frequency estimation method based on a LoG operator and a t test. Background technique [0002] Due to the complexity of the working environment, rotating machinery often works under variable speed conditions. Instantaneous frequency estimation is an important prerequisite for evaluating the operating state and fault diagnosis of rotating machinery. The most commonly used instantaneous frequency estimation method is the one-step cost function method. The one-step cost function method can search for ridge points in the local frequency range, but the center point of the local frequency range depends on the position of the previous ridge point, which leads to a delay in the one-step cost function. In addition, the width of the local frequency range is set arbitrarily according to experience, and the width at any moment is f...

AI Technical Summary

Problems solved by technology

The one-step cost function method can search for ridge points in the local frequency range, but the center point of the local frequency range depends on the position of the previous ridge point, which leads to a delay in the one-step cost function

In addition, the width of the local frequency range is set arbitrarily based on experience, and the width at any moment is fixed and cannot change with time, which leads to a lack of sufficient adaptability of the one-step cost function

The above defects lead to the low accuracy and precision of the one-step cost function method in estimating the instantaneous frequency

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