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Diesel engine high-frequency pressure oscillation signal extraction method based on improved wavelet packet transformation

A technology of wavelet packet transformation and oscillating signals, applied in genetic models, genetic rules, computer components, etc., can solve problems such as frequency confusion and unsatisfactory frequency-domain cut-off characteristics of wavelet filter banks, and achieve frequency confusion and amplitude distortion Reduced phenomena, guaranteed convergence and accuracy, and reduced calculations

Active Publication Date: 2018-12-07
HARBIN ENG UNIV
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Problems solved by technology

However, the traditional intelligent algorithm will have the problem of local convergence, so that the frequency-domain cut-off characteristics of the constructed wavelet filter bank are still not ideal, and there are still serious frequency confusions in the wavelet transform.

Method used

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  • Diesel engine high-frequency pressure oscillation signal extraction method based on improved wavelet packet transformation
  • Diesel engine high-frequency pressure oscillation signal extraction method based on improved wavelet packet transformation
  • Diesel engine high-frequency pressure oscillation signal extraction method based on improved wavelet packet transformation

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Embodiment Construction

[0022] The following examples describe the present invention in more detail.

[0023] Overall block diagram of the present invention is as attached figure 1 shown, with figure 1 The specific steps are as follows:

[0024] Step 1: Normalize the wavelet filter coefficients. define h k is the coefficient of the wavelet low-pass filter, since the sequence {h k} needs to meet many constraints, and its construction must be very complicated. And a sequence of length N {h k} can use a sequence of length N / 2-1 {θ k} to express:

[0025]

[0026] In the formula

[0027] E(z)=V N′-1 (z)V N′-2 (z)···V 1 (z)V 0 (z) (2)

[0028]

[0029]

[0030]

[0031]

[0032] In the formula N'=N / 2, z means e jω , H(z), G(z) are the Fourier transform of low-pass and high-pass wavelet filter coefficients respectively. For the sequence {θ k} initialization, so that it can be used for optimization in the following steps.

[0033] Step 2: Optimizing the normalized wavelet f...

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Abstract

The invention provides a diesel engine high-frequency pressure oscillation signal extraction method based on improved wavelet packet transformation. The method comprises the following steps: 1, normalization is performed on wavelet filter coefficients; 2, after the normalization is performed on the wavelet filter coefficients, the normalized filter coefficients are taken as individuals in a chicken flock, initialization of the chicken flock algorithm is achieved, and, after a cost function is built, wavelet filters are optimized according to individual fitness by utilizing the flock algorithm;3, a filter group obtained in step 2 is used as an initial value of a sequence secondary planning method to perform secondary iteration optimization, and a cost function is consistent with the step 1; and 4, a diesel engine cylinder pressure signal is subjected to three-layer wavelet packet transformation by utilizing the wavelet filter group built in steps 2 and 3, and a high-frequency pressureoscillation signal is extracted. The calculation amount of the diesel engine high-frequency pressure oscillation signal extraction method is greatly reduced compared with the calculation amount of anexisting wavelet improvement method; the wavelet filter group with a frequency domain characteristic very close to ideal cutoff can be built, and frequency confusion and amplitude distortion phenomenain the wavelet packet transformation process are greatly reduced.

Description

technical field [0001] The invention relates to a method mainly used for extracting high-frequency pressure oscillation signals of diesel engines. Background technique [0002] By extracting and analyzing the high-frequency pressure oscillation signal of the diesel engine, the condition monitoring and combustion noise estimation of the diesel engine can be realized. The high-frequency pressure oscillation signal exists in the cylinder pressure signal, so in order to extract the characteristics of the high-frequency pressure oscillation signal, the cylinder pressure signal needs to be decomposed. Therefore, effective signal extraction techniques are crucial for the analysis of high-frequency pressure oscillation signals. Wavelet packet transform is the most widely used signal feature extraction method. However, there is serious frequency confusion in the traditional wavelet packet transform, so many improved wavelet packet transform methods have been proposed, among which "...

Claims

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Application Information

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IPC IPC(8): G06K9/00G06N3/00G06N3/12H03H17/02
CPCH03H17/0211G06N3/006G06N3/126G06F2218/06G06F2218/08G06F2218/12
Inventor 杜敬涛陈曦明刘龙
Owner HARBIN ENG UNIV
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